US20070189667A1 - Display element and display device using the same - Google Patents
Display element and display device using the same Download PDFInfo
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- US20070189667A1 US20070189667A1 US11/784,617 US78461707A US2007189667A1 US 20070189667 A1 US20070189667 A1 US 20070189667A1 US 78461707 A US78461707 A US 78461707A US 2007189667 A1 US2007189667 A1 US 2007189667A1
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- waveguide
- light
- lateral face
- electrode film
- actuators
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
- G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
- G02B6/0033—Means for improving the coupling-out of light from the light guide
- G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
- G02B6/0038—Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
- G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/3433—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices
- G09G3/3473—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices based on light coupled out of a light guide, e.g. due to scattering, by contracting the light guide with external means
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/3502—Optical coupling means having switching means involving direct waveguide displacement, e.g. cantilever type waveguide displacement involving waveguide bending, or displacing an interposed waveguide between stationary waveguides
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/35—Optical coupling means having switching means
- G02B6/3564—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details
- G02B6/3568—Mechanical details of the actuation mechanism associated with the moving element or mounting mechanism details characterised by the actuating force
- G02B6/357—Electrostatic force
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/3406—Control of illumination source
- G09G3/3413—Details of control of colour illumination sources
Definitions
- the present invention relates to display elements and display devices using these display elements in which display is carried out by extracting light propagated by a waveguide from a lateral face of the waveguide.
- Display devices in which light propagated by a waveguide is extracted from a lateral face of the waveguide are disclosed in JP H7-287176A (particularly pages 6-7 and FIGS. 1 to 20 ) and JP H11-202222A (particularly pages 3-4, paragraph (0010), and FIG. 2 ) for example.
- These display devices are provided with actuator portions that are connected to light extraction portions and made of a ceramic piezoelectric film. Rest and displacement of the actuator portion is carried out by applying a voltage to the actuator portion such that the light extraction portion comes in contact with or moves away from the light waveguide, thereby extracting leakage light in a controlled manner.
- FIG. 3 of JP H11-202222A shows the transmissivity of light when evanescent light of light that is totally reflected by a total reflection surface is extracted at an extraction surface that has been brought in to proximity with the total reflection surface. According to this, transmissivity of approximately 50% is shown for light that has an incident angle in the range of 50° to 80° to the total reflection surface when the distance between the total reflection surface and the extraction surface is in the range of 0.1 to 0.05 ⁇ m.
- a display device is disclosed in “Waveguide Panel Display Using Electromechanical Spatial Modulators,” X. Zhou, E. Gulari, SID98 Digest, 1998, pages 1,022 to 1,025, in which an electrostatic actuator, in which a metal electrode film is formed on a polyimide film, is used as the actuator portion and an LED is used as the light source.
- an electrostatic actuator in which a metal electrode film is formed on a polyimide film, is used as the actuator portion and an LED is used as the light source.
- the thickness of the waveguide is 0.5 mm.
- a surface of the waveguide is an ITO film
- the surface of the light extraction portion that comes into contact with the ITO film is made by forming a film doped with titanium dioxide particles, which affect the diffusion properties of the polyimide, on an electrode, such that this film becomes a composite material harder than polyimide.
- the above-described conventional display device has low efficiency in extracting from the waveguide the light that is propagated in the waveguide. Moreover, unless the light extraction portion exerts a large pressure on the waveguide, the extracted light has insufficient brightness and is uneven.
- the present invention has been devised to solve these issues, and it is an object thereof to provide a display element and a display device in which light propagated in a waveguide can be extracted with high efficiency from a lateral face of the waveguide.
- a display element is provided with a light source and a waveguide that propagates a light emitted from the light source, wherein the light propagated in the waveguide is extracted to the outside from a waveguide lateral face, and wherein the light is extracted out of the waveguide from the waveguide lateral face by changing a shape of the waveguide lateral face.
- FIG. 1 is a cross-sectional view showing a structure of a display element according to Embodiment 1 of the present invention.
- FIG. 2 is a perspective view showing a structure of a display device according to Embodiment 1 of the present invention.
- FIG. 3 is a block diagram showing a structure of a display device according to Embodiment 1 of the present invention.
- FIG. 4 is a cross-sectional view showing a structure of a display element according to Embodiment 2 of the present invention.
- FIG. 5 is a cross-sectional view showing a structure of a display element according to Embodiment 3 of the present invention.
- FIG. 6 is a perspective view showing a structure of a display device according to Embodiment 3 of the present invention.
- FIG. 7 is a block diagram showing a structure of a display device according to Embodiment 3 of the present invention.
- FIG. 8 is a cross-sectional view showing a structure of a display element according to Embodiment 4 of the present invention.
- a display device extracts, from a lateral face of a waveguide, light that is propagated in the waveguide by changing the shape of the waveguide lateral face, and therefore is capable of extracting propagated light with high efficiency. This makes possible a display that is bright and uniform.
- the display element is further provided with a plurality of actuators that change a shape of the waveguide, wherein the shape of the waveguide lateral face is changed by selectively operating the actuators to extract the light out of the waveguide from the waveguide lateral face. In this way, light propagated in the waveguide can be extracted with high efficiency.
- the waveguide is provided with a core and a cladding formed along one lateral face of the core, wherein the actuators are attached to the cladding and a shape of the waveguide lateral face is changed by deforming the actuators. In this way, light propagated in the waveguide can be extracted with high efficiency.
- the light is extracted out of the waveguide by deforming at least a portion of the core of the waveguide. In this way, light can be extracted precisely.
- the actuators are attached to the waveguide lateral face, and a shape of the waveguide lateral face is changed by deforming the actuators. In this way, light can be extracted easily.
- the actuators are provided with a piezoelectric element, and a shape of the waveguide lateral face is changed by deforming the piezoelectric element by applying a voltage to the piezoelectric element. In this way, actuators that operate at high speed can be formed and therefore high precision video display can be supported.
- the actuators are provided with a first electrode film arranged at the waveguide lateral face, a piezoelectric element layered on the electrode film, and a second electrode film layered on the piezoelectric element, wherein the shape of the waveguide lateral face is changed by deforming the piezoelectric element by applying a voltage between the first electrode film arranged at the waveguide lateral face and the second electrode film layered on the piezoelectric element. In this way, high efficiency light extraction can be achieved with small external pressure.
- the actuators are provided with a convex portion, and a shape of the waveguide lateral face is changed by applying pressure to the waveguide lateral face with the convex portion. In this way, high efficiency light extraction can be achieved easily.
- the actuators are provided with: an electrode film arranged at the waveguide lateral face, and an external electrode film that is in opposition to and adjacent to the waveguide, wherein the shape of the waveguide lateral face is changed by an electrostatic force produced by applying a voltage between the external electrode film and the electrode film. In this way, high efficiency light extraction can be achieved easily.
- the external electrode film is provided with a convex portion at the waveguide lateral face, and a shape of the waveguide lateral face is changed by the convex portion of the external electrode film applying pressure to the waveguide lateral face by using the electrostatic force. In this way, actuators that operate at high speed can be formed and therefore high precision video display can be supported.
- the light is extracted out of the waveguide by deforming at least a portion of the core of the waveguide. In this way, light can be extracted precisely.
- the waveguide is made of an elastic material. In this way, high efficiency light extraction is possible with small external pressure.
- the actuators are formed for each pixel. This makes possible a display using an active matrix.
- the waveguide is provided with a waveguide electrode film on the waveguide lateral face, an opposing electrode film that opposes the waveguide electrode film, and particles arranged between the waveguide electrode film and the opposing electrode film, wherein, by applying a voltage between the waveguide electrode film and the opposing electrode film, the particles and the waveguide electrode film are brought into contact such that the light is extracted out of the waveguide from the waveguide lateral face.
- the particles and the waveguide can be integrated by bringing the particle into contact with the waveguide electrode film, and the light can be extracted out of the waveguide from the waveguide lateral face by changing the shape of the waveguide lateral face. In this way, high efficiency light extraction is possible by applying only a very uniform and small pressure.
- the light is extracted out of the waveguide by deforming at least a portion of the core of the waveguide. In this way, light can be extracted precisely.
- the particle is electrically charged. In this way, it is possible to control the particle with an electrostatic force and therefore control can be achieved easily.
- the particle has a magnetic property. In this way, it is possible to control the particle with an electrostatic force and therefore control can be achieved easily.
- a surface tension of the waveguide electrode film and a surface tension of a surface of the particles are different from each other. In this way, it is easy to cause the particles to contact the waveguide electrode film. For this reason, contact and non-contact of the particles can be controlled with a low voltage.
- a coating material is applied to the waveguide electrode film. In this way, it is easy to cause the particles to contact the waveguide electrode film. For this reason, contact and non-contact of the particles can be controlled with a low voltage.
- the waveguide electrode film and the opposing electrode film are provided for each pixel. This makes possible display using an active matrix.
- the particle is fluorescent. In this way, it is possible to extract light of various wavelengths by varying the wavelength of the light from the light source.
- the light source emits ultraviolet light. In this way, it is possible to achieve RGB display even when the light source is one type of LED.
- the light source is a 3-color LED or a 3-color laser. In this way, the number of waveguides can be reduced.
- the display device is provided with: the above-described display element, the light source drive circuit for driving the light source, an actuator drive circuit for driving the actuator, and a control circuit that controls the light source drive circuit and the actuator drive circuit. In this way, it is possible to achieve a display device capable of higher luminance and uniform display with lower power consumption.
- the light source drive circuit for driving the light source
- a particle drive circuit for applying a voltage between the waveguide electrode film and the opposing electrode film
- a control circuit that controls the light source drive circuit and the particle drive circuit.
- the display element is preferably provided with the above-described display element and an active matrix element that controls respective voltages between the waveguide electrode films and the opposing electrode films. This achieves a display device using an active matrix.
- the active matrix elements may be a TFT or a TFD.
- FIG. 1 is a cross-sectional view showing a structure of a display element 1 according to Embodiment 1 of the present invention.
- the display element 1 is provided with a light source 2 , a waveguide 3 that propagates the light emitted from the light source 2 , and a plurality of actuators 4 that change the form of the waveguide 3 .
- the waveguide 3 is provided with a core 3 a, through which light propagates, and a cladding 3 b.
- the cladding 3 b is arranged along the surface on one side of the core 3 a. Cladding is not arranged on the surface on the opposite side from the cladding 3 b such that air acts as the cladding there.
- a sheet of silicone gel which is an extremely soft material, with a thickness of 100- ⁇ m for example may be used as the core 3 a, through which light propagates.
- a transparent fluoric polymer for example with a low refractive index may be used as the cladding 3 b.
- the core 3 a is coated with the cladding 3 b to a thickness of 10 ⁇ m.
- the light source 2 is arranged at an end portion of the waveguide 3 and the light source 2 is arranged with an orientation such that the light emitted from the light source 2 is coupled into the waveguide 3 .
- a 3-color LED for example is used as the light source 2 .
- the 3-color LED can have a structure in which RGB 3-color LED chips are accommodated in a single lamp, with each color independently controlled.. In conventional flat panel displays using LCD or PDP, the pixels of the three RGB colors are separated in a stripe form.
- Embodiment 1 by using a 3-color LED, the light of the three colors R, G, and B can be input to a single waveguide 3 , and therefore it is possible for a single waveguide 3 to emit any of the three colors R, G, and B. It should be noted that it is preferable for a prism 2 a to be placed and optically coupled at an incident location of the waveguide 3 to facilitate entrance of the light from the light source 2 even when the waveguide 3 is thin.
- the actuators 4 are provided with a piezoelectric element 4 a, and electrode films 4 b and 4 c that are arranged respectively on opposite sides of the piezoelectric element 4 a.
- the actuators 4 are attached at a lateral face on the cladding 3 b side of the waveguide 3 .
- the piezoelectric element 4 a may be polyvinylidene fluoride (PVDF) for example, on which a plurality of the electrode films 4 b and the electrode film 4 c are formed by applying on both sides thereof a silver paste for example.
- PVDF polyvinylidene fluoride
- the actuators 4 are attached with an adhesive at a lateral face, that is, the cladding 3 b, of the waveguide 3 .
- the electrode films 4 b have a width of 70 ⁇ m and are formed in a striped pattern with a pitch of 90 ⁇ m. It should be noted that these stripes are formed extending vertically with respect to the paper plane in FIG. 1 . Four of these stripes of electrode films 4 b constitute a single actuator 4 . Furthermore, the electrode film 4 c facing the electrode films 4 b is a continuous coating that spreads uniformly on the waveguide 3 and is shared by a plurality of actuators 4 .
- the lengths of the cladding 3 b and the piezoelectric film 4 a are the same when no voltage is applied, and therefore the actuators 4 assume a planar shape.
- Light of a desired color emitted from the light source 2 is propagated in the waveguide 3 .
- a portion of the light propagated in the waveguide 3 for example, a light 2 c shown as a dot-dash line, undergoes a change of angle with respect to the surface of the core 3 a, and therefore is emitted out of the waveguide 3 from a lateral face (the side on which actuators 4 of the waveguide 3 are not arranged) of the waveguide 3 after being totally reflected.
- a light 2 b which is shown by a broken line, is transmitted through the core 3 a and the cladding 3 b due to the changed form of the waveguide 3 and is then reflected by the silver electrode film 4 c such that it is scatter-reflected and emitted out of the waveguide 3 from a lateral face of the waveguide 3 .
- the greater the voltage applied to the actuators 4 the greater the change in form of the waveguide 3 .
- Increases in the luminance of the extracted light were observed according to measurements along with gradual increases in applied voltages starting from zero. Luminance was saturated when the voltage applied was ⁇ 30 volts and it was possible to extract 80% or more of the light from the light source 2 that was incident on the waveguide 3 .
- a light source 2 that provides high directivity for emitted light is preferable for extracting light efficiently.
- the total reflection angle at the interface between the core 3 a and the air is 60°. Accordingly, when the angle (incident angle) of the light propagated in the waveguide 3 with respect to the normal line of the display surface la is smaller than 41.8°, which is the critical angle, light leaks from the waveguide 3 . Conversely, when the incident angle is large and the travel direction of the light is close to parallel to the waveguide 3 , total reflection occurs repetitively in the core 3 a and the spacing between locations of such total reflection becomes extremely large such that locations in which light extraction is desired are passed over, thus tending to reduce efficiency and produce uneven luminance.
- the incident angle of light emitted from the light source 2 to the waveguide 3 is larger than the critical angle of 41.8° but close to the critical angle of 41.8° with a light of high directivity.
- the light source 2 is an LED
- the directivity can be varied according to the shape of the lens that is molded, and therefore the half-value width of the emitted light angle distribution of the 3-color LED serving as the light source 2 was set at approximately 10°.
- a light source 2 other than an LED.
- a light source 2 in which directivity has been improved by arranging a micro-lens array on an organic EL panel and it is also possible to use a semiconductor laser as the light source 2 .
- the waveguide 3 When the waveguide 3 is too thick, the light propagated inside the waveguide 3 undergoes repetitive total reflection at the display surface 1 a (the interface between the waveguide 3 and the air) and the spacing between locations of total reflection becomes extremely large. For this reason, the propagated light may pass over the arranged locations (pixels) of the actuators 4 , thus bringing about light beams that cannot be extracted. Therefore, it is preferable that the waveguide 3 is not too thick.
- the thickness D of the waveguide 3 in FIG. 1 is preferable in terms of efficient extraction.
- the thickness of the waveguide 3 is determined according to the number of pixels and the size of the display area.
- the length L of the portions of the waveguide 3 that are made to change form by the actuators 4 corresponds to the length of one pixel in the horizontal direction (propagation direction of light in the waveguide 3 ).
- the display size of a display device 100 using the display element 1 described below is that of a HDTV in the range of 60 to 100 inches.
- the size of a single pixel is approximately in the range of 230.6 ⁇ m (vertical) ⁇ 691.8 ⁇ m (horizontal) to 384.3 ⁇ m (vertical) ⁇ 1,153 ⁇ m (horizontal).
- the thickness D of the waveguide 3 here is preferably not greater than 345.9 ⁇ m and not greater than 576.5 ⁇ m.
- the thickness D of the waveguide 3 is preferably not greater than 1 ⁇ 2 of the length L (the length of the actuators 4 in the propagation direction of light in the waveguide 3 ) of the portions of the waveguide 3 that are made to change form by the actuators 4 .
- the thickness of the core 3 a is at least 30 ⁇ m or more.
- FIG. 2 is a perspective view showing a structure of the display device 100 according to Embodiment 1.
- the display device 100 can be configured by arranging in a row a plurality of the display elements 1 such that the display surfaces la are on the same side.
- the waveguides 3 of the display elements 1 are arranged in an array of n rows in the row direction (X direction) of the screen.
- n is a natural number.
- the respective light sources 2 are arranged at end portions of the waveguides 3 and actuators 4 for m lines are arranged in a line direction (Y direction), which is the direction in which waveguides 3 extend.
- the number of pixels of the display device 100 is n ⁇ m pixels.
- a display device 100 according to Embodiment 1 operates the actuators 4 in line sequence to change the form of the lateral face of the waveguide 3 and thereby change the direction in which light conveyed in the waveguide 3 by total reflection is reflected, thus extracting light from within the waveguide 3 and causing the light emission from the display surface 1 a.
- a display device 100 with this configuration is capable of displaying a given image by controlling the application of voltages to the various chips for the 3-color LEDs serving as the light sources 2 for the waveguides 3 that extend in the row direction of the display plane (XY plane), based on the color and luminance information of the pixels on the lines for which extraction is selected with the electrode films 4 b and the electrode film 4 c.
- FIG. 3 A block diagram showing a configuration of the display device 100 of Embodiment 1 is shown in FIG. 3 .
- FIG. 3 illustrates a specific configuration for actually operating the display device 100 .
- the display device 100 is provided with a light source drive circuit 50 for driving the light sources 2 , an actuator drive circuit 51 for driving the actuators 4 by applying voltages to the electrode film 4 b and 4 c, and a control circuit 52 that synchronizes these circuits, inputs signals, and displays images.
- the control circuit 52 inputs luminance information of the colors RGB of pixels in lines selected by the actuator drive circuit 51 to the driver LSI of the light source drive circuit 50 , and the light source drive circuit 50 inputs applied voltages corresponding to the luminance information to the light sources 2 to enable full color image display.
- 3-color LEDs are used as the light sources 2 , it is possible to make light of three colors incident on a single waveguide 3 . This makes it possible to display light of three colors with a single display element 1 , that is, with one line.
- a pixel is configured by three sub-pixels of the three primary colors R, G, and B.
- the display device using the waveguide 3 of Embodiment 1 it is not necessary to divide the waveguides 3 that extend in the row direction for each color and the three primary colors can be incident on a single waveguide 3 , and therefore it is possible to reduce the number of waveguides 3 (display elements 1 ), thus providing the effect of reduced costs.
- Uniformly bright planar display could be confirmed by sequentially applying voltages of ⁇ 30V to the actuators 4 in the display elements 1 of the display device 100 .
- voltages of ⁇ 30V With conventional structures in which light is extracted using evanescent waves, it has not been possible to reduce to zero the distance between the waveguide and the light extraction surface due to the influence of submicron size particulates that exist in multitude even in clean rooms. For this reason, it has not been easy to achieve high extraction efficiency even when pressing the light extraction surface against the waveguide with considerable force.
- the display element 11 of Embodiment 2 is provided with a light source 2 , a waveguide 3 that propagates the light emitted from the light source 2 , and actuators 14 that change the form of the waveguide 3 .
- the light source 2 and the waveguide 3 are the same as in the display element 1 of Embodiment 1.
- the light source 2 is a 3-color LED for example, and the light emitted by the light source 2 propagates in the waveguide 3 .
- the waveguide 3 is provided with a core 3 a and a cladding 3 b, and since the core 3 a is exposed on the opposite side of the cladding 3 b, the air acts as cladding.
- the core 3 a is a flat sheet of a 100 ⁇ m thickness and is made of a silicone gel material, while the cladding 3 b is a transparent fluoric resin with a film thickness of 5 ⁇ m.
- the actuators 14 are provided with an electrode film 14 a arranged on a lateral face of the waveguide 3 , a polycarbonate insulation thin film 14 b of a thickness of 0.1 ⁇ m for example that is applied to the electrode film 14 a, a substrate 14 d made of 0.15 mm thick PET film arranged in opposition to the insulation thin film 14 b, and external electrode films 14 c, which are formed on the substrate 14 d on the insulation thin film 14 b side and have a concavo-convex shape.
- the electrode film 14 a is formed on the entire surface of the waveguide 3 (cladding 3 b ) and is common with respect to the actuators 14 .
- a method for manufacturing the above-described waveguide 3 and the actuators 14 is to coat the cladding 3 b on the core 3 a for example, then further apply a silver paste with screen printing for example on the surface of the cladding 3 b to form the electrode film 14 a. Further still, a polycarbonate is applied to the electrode film 14 a to form the insulation thin film 14 b. Then, an indented concavo-convex portion 14 e is formed by being pressed formed in a striped pattern on the surface of the substrate 14 d, which is made of a 0.15 mm thick PET film. The concavo-convex portion 14 e has a cross-sectional depth of 3 ⁇ m for example and a pitch of 30 ⁇ m. The aluminum external electrode films 14 c are formed on the concavo-convex portion 14 e by carrying out aluminum deposition for example. Finally, the substrate 14 d and the waveguide 3 are arranged so as to oppose each other.
- the electrode film 14 a and the external electrode film 14 c cling toward each other and the electrode film 14 a and the external electrode film 14 c are deformed to the same concavo-convex shape.
- the electrode film 14 a is adhering to the waveguide 3 , and therefore the cladding 3 b and the surface of the core 3 a are deformed to the same concavo-convex shape as the external electrode films 14 c. That is, the lateral face of the waveguide 3 changes shape.
- the core 3 a is particularly soft and therefore changes shape greatly. In this way, light that is being propagated while being totally reflected in the waveguide 3 can be extracted to the outside from the lateral face of the waveguide 3 .
- a light 12 c that is being propagated while being totally reflected in the waveguide 3 by the surfaces of the core 3 a can be leaked to the outside from the lateral face of the waveguide 3 by deforming the lateral face on one side of the waveguide 3 .
- the light 12 c shown by the one-dot dash line for example is emitted out of the waveguide 3 from the lateral face (the side on which the actuators 4 of the waveguide 3 are not arranged) of the waveguide 3 after being totally reflected since the angle of the surface of the core 3 a changes. Furthermore, there is also light for example that penetrates the core 3 a and the cladding 3 b and is then reflected by the silver electrode film 14 a such that it is scatter-reflected and emitted out of the waveguide 3 from a lateral face of the waveguide 3 .
- a display device can be configured in the same way as the display device 100 by arranging in a row a plurality of the display elements 11 shown in FIG. 4 vertical with respect to the propagation direction of light in the waveguide 3 , such that the display surfaces la are on the same side, as shown in FIG. 2 .
- the number of pixels when n rows of the display elements 11 are arranged in the row direction of the screen and actuators 14 for m lines are arranged in the direction (line direction) in which the waveguides 3 extend is n ⁇ m pixels.
- the method for achieving extraction from the lateral face (display surface 1 a ) of the waveguide 3 to carry out image display is the same as for the display device 100 of Embodiment 1, and therefore will not be further explained. Only the structure of the actuators is different between the display device of Embodiment 1 and the display device of Embodiment 2, and the rest of the structure is substantially the same.
- a light source drive circuit 50 for driving the light sources 2 an actuator drive circuit 51 for driving operating the actuators 14 by applying voltages to the electrode films 14 a and 14 c, and a control circuit 52 that synchronizes these circuits, inputs signals, and displays images.
- the entire core 3 a was structured with the same material, but it is sufficient for the surface of the core 3 a of the waveguide 3 to be easily deformable, and therefore the surface on the side of the waveguide 3 may be structured with a hard material such as an ordinary plastic while only locations to be deformed are structured as layers arranged by a soft layer. Furthermore, it is also possible to use a waveguide 3 in which only the core 3 a is structured without the cladding 3 b such that the cladding on both sides is air. Furthermore, to facilitate handling, it is possible to use a waveguide 3 in which cladding is provided on both sides of the core 3 a.
- a simple matrix type display device was shown in which the waveguides 3 were arrayed according to the number of rows and a plurality of 3-color LED light sources 2 were arranged, but the type of light source and the type of actuator, as well as the structure of the positioning of these is in no way limited to this. Any structure by which it is possible to achieve high extraction efficiency with low power by deforming a soft waveguide 3 may be used.
- a structure is possible in which the waveguide 3 is made of a single flat sheet with a single light source 2 arranged in an XY matrix with a number of actuators 4 or 14 according to the number of pixels.
- an active element that, drives the actuators 4 or 14 are added to each actuator and driven for each pixel such that gradation is carried out by controlling the time in which the core deforms.
- a TFT thin flat transistor
- TFD thin flat diode
- the light extraction efficiency is improved in display elements and display devices that use a technique in which light propagated in the waveguide 3 is extracted from the lateral face of the waveguide, which enables greater luminance with reduced power consumption as well as improved uniformity of display. Furthermore, it is possible to achieve sheet-shaped thin display devices regardless of the screen size even for large screens exceeding 100 inches and small screens for mobile applications.
- FIG. 5 is a cross-sectional view showing a structure of a display element 21 according to Embodiment 3.
- the display element 21 is provided with a light source 22 , a waveguide 23 , an opposing electrode film 25 that opposes the waveguide 23 , and particles 26 arranged near the waveguide 23 .
- the waveguide 23 is provided with a core 23 a that propagates light, a cladding 23 b, and waveguide electrode films 23 c.
- a sheet of acrylic resin for example, which is an extremely soft material, with a thickness of 100- ⁇ m is used as the core 23 a.
- a transparent fluoric polymer that has a low refractive index is coated as the cladding 23 b to a thickness of 10 ⁇ m on a surface on one side of the core 23 a.
- the waveguide electrode films 23 c are ITO and are attached directly with an adhesive on a surface on the opposite side of the core 23 a from the cladding 23 b.
- the cladding 23 b is arranged on one surface only of the core 23 a and a plurality of the waveguide electrode films 23 c are arranged on the reverse surface.
- the waveguide electrode films 23 c are ITO and a plurality of these are arranged in the direction in which the waveguide 23 extends.
- the length W of the waveguide electrode film 23 c in the propagation direction of light in the waveguide 23 is 300 ⁇ m for example.
- the cladding on the opposite side of the cladding 23 b is air.
- the waveguide electrode films 23 c are a portion of the core and the light propagated in the waveguide 23 is also totally reflected by the interface of the waveguide electrode films 23 c and the air. It should be noted that this also may be a structure in which no cladding 23 b is provided.
- the light source 22 is arranged at an end portion of the waveguide 23 and the light source 22 is arranged with an orientation such that the light emitted from the light source 22 is coupled into the waveguide 23 . It is preferable that a prism 22 a is placed and optically coupled at an incident location of the waveguide 23 . It should be noted that the light source 22 may be the same as the light source 2 in Embodiment 1 and it is preferable that a 3-color LED is used for example.
- a light source 22 that has high directivity is preferable to enable efficient extraction of light from the waveguide 23 .
- the total reflection angle at the interface between the core 23 a and the air is 60°.
- the state of light propagation in the waveguide 23 is shown conceptually in the cross-sectional view of FIG. 5 .
- the incident angle (angle with respect to the normal line of the display surface 21 a ) to the waveguide 23 of the light 22 b shown as a broken line emitted from the light source 22 is smaller than 41.8°, which is the critical angle in Embodiment 3, the light 22 b leaks from the waveguide 23 .
- the incident angle is greater than the critical angle of 41.8° as with the light 22 c shown by the dot-dash line, the travel path of the light 22 c is close to parallel to the waveguide 23 .
- the incident angle of light emitted from the light source 22 to the waveguide 23 is larger than the critical angle of 41.8° but close to the critical angle of 41.8° with a light source 22 of high directivity.
- the light source 22 is an LED
- the directivity can be varied according to the shape of the lens that is molded, and is therefore preferable. That is why, in Embodiment 3, a 3-color LED in which the half value width of the emitted light angle distribution is set to 10° is used as the light source 22 .
- a light source whose directivity has been improved by arranging a micro-lens array on an organic EL panel, as the light source 22 , and it is also possible to use a semiconductor laser.
- 3-color LED as the light source 22 , it is easier to make light of three colors incident on a single waveguide 23 .
- a pixel is configured by three sub-pixels of the three primary colors R, G, and B, but by configuring a pixel as described above, it is not necessary to divide the waveguides 23 that extend in the row direction for each color and the three primary colors can be incident on a single waveguide 23 . Therefore it is possible to reduce the number of waveguides 23 , thus providing the effect of reduced costs.
- the opposing electrode film 24 is arranged in opposition to the waveguide 23 .
- the opposing electrode film 24 is ITO for example, and is deposited on a substrate 25 of an acrylic resin.
- the spacing between the waveguide electrode film 23 c and the opposing electrode film 24 is 35 ⁇ m for example.
- Particles 26 are arranged in the vicinity of the waveguide 23 .
- the particles 26 are positioned between the waveguide electrode film 23 c and the opposing electrode film 24 , are made of an acrylic resin, and are electrically charged.
- the mean particle size of the particles 26 is 6 ⁇ m for example.
- the particles 26 are filled into the space between the waveguide electrode film 23 c and the opposing electrode film 24 to a filling rate of 20%. It should be noted that the filling rate is the ratio of the volume occupied by the particles per unit of volume.
- the volume occupied by the particles 26 can be obtained by multiplying the number of particles 26 per unit of volume by the volume per particle that is obtained from the mean particle size of the particles 26 .
- the particles 26 contact the surface of the waveguide electrode film 23 c. In this way, the particles 26 and the waveguide 23 become integrated. That is, the particles 26 become a portion of a lateral face of the waveguide 23 and the shape of the lateral face of the waveguide 23 on the side of the waveguide electrode film 23 c is changed.
- Light of a desired color emitted from the light source 22 is propagated in the waveguide 23 .
- the shape of the lateral face of the waveguide 23 on the side of the waveguide electrode film 23 c is changed by the particles 26 .
- the shape of the waveguide 23 the state of propagation changes and the light that has been propagated in the waveguide 23 leaks outside from the waveguide lateral face of the waveguide 23 .
- the refractive index of the particles 26 By setting the refractive index of the particles 26 to approximate the refractive index of the core 23 a or the cladding 23 b, it is possible to extract light to the outside from the particles 26 . It is preferable that the refractive index of the particles 26 for example is substantially equivalent to the refractive index of the core 23 a.
- particles 26 made of an acrylic resin containing rhodamine, which is a fluorochrome may be used as the particles 26 .
- the light extracted from the lateral face of the waveguide 23 when using a green LED that emits a 520 nm wavelength light as the light source 22 was observed to be an orange light with a wavelength of 580 nm.
- particles 26 that contain a fluorochrome or a fluorescent substance, and an LED light source 22 that corresponds to the excitation wavelength of the fluorochrome or the fluorescent substance it is possible to extract light, of various wavelengths.
- an ultraviolet light LED as the light source 22 and by using the fluorescent substances used in PDPs as the particles 26 , it is possible to achieve display of RGB even when using a single color LED as the light source 22 .
- FIG. 6 is a perspective view showing a structure of the display device 300 according to Embodiment 3.
- the display device 300 can be configured by arranging a plurality of the above-described display elements 21 in a row vertically with respect to the propagation direction of light in the waveguide 23 .
- the waveguides 23 of the display elements 21 are arranged in an array of n rows in the row direction (X direction) of the screen. It should be noted that n is a positive integer.
- the light sources 22 are arranged respectively at end portions of the waveguides 23 .
- the electrode films 23 c for m lines are arranged in the line direction (Y direction), which is the direction in which waveguides 23 extend.
- the opposing electrode film 24 for the display elements 21 is common and is arranged such that it covers all the waveguides 23 of the display elements 24 .
- the waveguide electrode films 23 c of the same line are shared by the respective waveguides 23 and cover the lines thereof.
- the number of pixels of the display device 300 is n ⁇ m pixels.
- the particles 26 are made to undergo contact or non-contact to the waveguide electrode film 23 c by controlling, line by line, the voltages applied between the waveguide electrode film 23 c and the opposing electrode film 24 such that light propagated in the waveguide 23 by total reflection is extracted from a lateral face of the waveguide 23 and emitted toward the opposing electrode film 24 .
- a display device 300 configured in this way is capable of displaying a given image by controlling the application of voltages to the various chips for the 3-color LEDs for the waveguides 23 that extend in the row direction of the display plane (XY plane), based on the color and luminance information of the pixels on the lines for which extraction is selected with the waveguide electrode film 23 c and the opposing electrode film 24 .
- FIG. 7 A block diagram showing a configuration of the display device 300 of Embodiment 3 is shown in FIG. 7 .
- FIG. 7 illustrates a specific configuration for actually operating the display device 300 .
- the display device 300 is provided with a light source drive circuit 60 for driving the light sources 22 , a particle drive circuit 61 for making the particles 26 undergo contact or non-contact with the waveguide electrode film 23 c by applying voltages to the waveguide electrode film 23 c and the opposing electrode film 24 , and a control circuit 62 that synchronizes these circuits, inputs signals, and displays images.
- the control circuit 62 inputs luminance information of the colors RGB of pixels in lines selected by the particle drive circuit 61 to the driver LSI of the light source drive circuit 60 , and the light source drive circuit 60 inputs applied voltages corresponding to the luminance information to the light sources 22 to enable full color image display.
- 3-color LEDs are used as the light sources 22 , it is possible to make light of three colors incident on a single waveguide 33 . This makes it possible to display light of three colors with a single display element 21 , that is, with one line.
- a pixel is configured by three sub-pixels of the three primary colors R, G, and B.
- the display device using the waveguide 23 of Embodiment 3 it is not necessary to divide the waveguides 3 that extend in the row direction for each color and the three primary colors can be incident on a single waveguide 23 . Therefore it is possible to reduce the number of waveguides 23 (display elements 21 ), thus providing the effect of reduced costs.
- the display element 31 according to Embodiment 4 is a structure in which a coating material 37 that has a relatively large surface tension is applied on the waveguide 23 of the display element 21 according to Embodiment 3, on the side on which the waveguide electrode film 23 c is arranged.
- the surface tension of the coating material 37 is preferably not less than 50 mN/m.
- the coating material 37 covers the core 23 a and the waveguide electrode film 23 c such that the coating material 37 is a portion of the core, and the light propagated in the waveguide 23 is also totally reflected by the interface of the coating material 37 and the air. Since the same function is indicated for portions other than the coating material 37 , the same numerical symbols will be used and their further description will be omitted.
- the coating material 37 is a glycerin for example with a surface tension of 63.4 mN/m and is applied to have a thickness of approximately 2 ⁇ m. Furthermore, it is preferable that a material with a small surface tension is used for the particles 26 . Specifically, the surface tension of the particles 26 is preferably not more than 30 mN/m.
- a display element 31 was actually formed using the particles 26 made of Teflon (registered trademark) with a surface tension of 18.4 mN/m, for example.
- the mean particle size of the particles 26 was set at 6 ⁇ m and the filling rate of the particles 26 in the space between the waveguide electrode film 23 c and the opposing electrode film 24 was set at 20%.
- a voltage of 50V was applied so that the waveguide electrode film 23 c of the selected line became negative and the opposing electrode film 24 became positive. In this way, the particles 26 came in contact with the surface of the waveguide electrode film 23 c and the leaked light from the contact portion was extracted toward the substrate 25 .
- Springiness is a physical phenomenon in which springing occurs without the coating material 37 spreading against surface of the particles 26 . That is, the greater the springiness between the particles 26 and the coating material 37 , the greater the rebound at contact between the particles 26 and the waveguide electrode film 23 c. For this reason, the particles 26 can be made to move away more easily from the waveguide electrode film 23 c. Accordingly, contact and non-contact between the particles 26 and, the waveguide electrode film 23 can be controlled with a low voltage.
- the coating material 37 with a different surface tension from the particles 26 on the surface of the core 23 a and the waveguide electrode film 23 c, it is possible to reduce the voltage required to control contact of the particles 26 .
- the surface tension of the particles 26 may be different from the surface tension of the surface of the waveguide 23 (the waveguide electrode film 23 c ).
- the structure is such that the surface tension of the particles 26 is smaller than the surface tension of the surface of the waveguide 23 .
- a display device can be configured in the same way as the display device 300 by arranging in a row a plurality of the display elements 31 shown in FIG. 8 vertical with respect to the propagation direction of light in the waveguide 23 , such that the display surfaces 21 a are on the same side, as shown in FIG. 6 .
- n rows of the display elements 31 are arranged in the row direction of the screen and the waveguide electrode film 23 c for m lines are arranged in the direction (line direction) in which the waveguides 3 extend the number of pixels is n ⁇ m pixels.
- the method for achieving extraction of a desired light from the lateral face (display surface 21 a ) of the waveguide 23 to carry out image display is the same as for the display device 300 of Embodiment 3, and therefore its explanation will be omitted.
- a point of difference between the display device of Embodiment 4 and the display device of Embodiment 5 is that the coating material 37 is arranged on a surface of the waveguide 23 and otherwise the structures are substantially the same.
- a light source drive circuit 60 for driving the light sources 22 a particle drive circuit 61 for making the particles 26 undergo contact or non-contact to the waveguide electrode film 23 c by applying voltages to the waveguide electrode film 23 c and the opposing electrode film 24 , and a control circuit 62 that synchronizes these circuits, inputs signals, and displays images.
- display of a given image was achieved by controlling the application of voltages to the various chips for the 3-color LEDs serving as the light sources 22 for the waveguides 23 that extend in the row direction of the display plane (XY plane), based on the color and luminance information of the pixels on the lines for which extraction is selected with the waveguide electrode film 23 c and the opposing electrode film 24 .
- the configuration of the type of light source and the positioning for example is not limited to these.
- a structure is possible in which the waveguide electrode film 23 c and the opposing electrode film 24 are arranged in an XY matrix corresponding to the number of pixels.
- each pixel may be driven by connecting an active element to the waveguide electrode film 23 c and the opposing electrode film 24 .
- a TFT or a TFD may be used as the active element for example.
- the light extraction efficiency is improved by controlling contact of the particles in a display device making use of a technique in which light is guided from an end face of the waveguide and light is extracted from a surface of core of the waveguide, thus making it possible to achieve higher luminance with lower power consumption. Furthermore, the uniformity of display is improved. With embodiments 3 and 4, it is possible to achieve sheet-shaped thin display devices regardless of the screen size even for large screens exceeding 100 inches and small screens for mobile applications.
- the present inventors produced a display device in which light is extracted from a waveguide with a structure that is the same as the conventional structure of the previously mentioned “Waveguide Panel Display Using Electromechanical Spatial Modulators,” X. Zhou, E. Gulari, SID98 Digest, 1998, pages 1,022 to 1,025.
- luminance was low and brightness is increased as thickness is reduced in conventional structures in which the thickness of the waveguide is thicker than the pixel width (width of propagation direction of light).
- the distance between locations of total reflection in the waveguide in which propagated light undergoes repetitive total reflection at the interface between the core and the air is dependent on the thickness of the waveguide. For example, for total reflection at a reflection angle of 45°, the distance between locations of total reflection is double the width of the waveguide. And for this reason the thickness of the waveguide must be not greater than 1 ⁇ 2 of the width of the pixels in the light propagation direction. If not, the distance between locations of total reflection becomes greater than the pixel width and the reflected light passes over the pixels such that extraction from the waveguide lateral face cannot be achieved.
- the thickness of the waveguide in the display element of embodiments 1 to 4 is preferably less than 1 ⁇ 2 of the pixel width and, moreover, in consideration of the angle distribution of the incident light, it is more preferably thinner still.
- the pixel width is the length of the electrodes 4 and 14 in the longitudinal direction of the waveguide 3 in FIGS. 1 and 2 for the display elements of embodiments 1 and 2, and is the length in the longitudinal direction of the waveguide electrode film 23 c or waveguide 23 in FIGS. 5 and 6 for embodiments 3 and 4.
- the thickness of the waveguide 3 and 23 when the thickness of the waveguide 3 and 23 is set at 1 ⁇ 4 or less than the pixel width, then light with a reflection angle of 60° or less also becomes extractable.
- light of an LED with high directivity is incident on such a waveguide, it is possible to extract almost all the incident light.
- the waveguides 3 and 23 are too thin, single mode is approached, at which the angles at which light can be propagated in the waveguide 3 and 23 are limited. This reduces the amount of light that can be transmitted.
- the thickness of the waveguide 3 and 23 are at least 30 ⁇ m.
- RGB 3-color laser
- a display element and a display device of the present invention can be used in sheet-shaped thin display devices regardless of the screen size even for large screens and small screens for mobile applications.
Abstract
A display element is provided with a light source and a waveguide that propagates a light emitted from the light source, wherein the light propagated in the waveguide is extracted to outside from a waveguide lateral face, and wherein the light is extracted out of the waveguide from the waveguide lateral face by changing a shape of the waveguide lateral face.
Description
- This application is a Division of application Ser. No. 10/533,663, filed May 3, 2005, which is a National Stage of PCT/JP2003/014047, which applications are incorporated herein by reference.
- The present invention relates to display elements and display devices using these display elements in which display is carried out by extracting light propagated by a waveguide from a lateral face of the waveguide.
- Display devices in which light propagated by a waveguide is extracted from a lateral face of the waveguide are disclosed in JP H7-287176A (particularly pages 6-7 and FIGS. 1 to 20) and JP H11-202222A (particularly pages 3-4, paragraph (0010), and
FIG. 2 ) for example. These display devices are provided with actuator portions that are connected to light extraction portions and made of a ceramic piezoelectric film. Rest and displacement of the actuator portion is carried out by applying a voltage to the actuator portion such that the light extraction portion comes in contact with or moves away from the light waveguide, thereby extracting leakage light in a controlled manner. - Display devices that use the above system have been implemented as large size display panels. A commercialized example of these is presented in a CeramVision/CeramBoard brochure (fifth page, lower left column) at the following Internet address: http://www.ngk.co.jp/ELE/product/07/index.html (accessed on Jul. 25, 2002).
- With traditional displays, light that is totally reflected and propagated within the waveguide is made to leak to the outside from a lateral face of the waveguide by bringing the waveguide and the light extraction portion together to a distance less than the wavelength of the light. That is, so called evanescent waves are extracted (particularly see paragraph (0009) of JP H7-287176A and claim 1 of JP H11-202222A). As shown in drawings such as
FIGS. 1 and 4 of JP H7-287176A, the extraction of light from a lateral face of the waveguide is controlled by whether or not a flat surface of a displacement transmission portion (light extraction portion) is made to come into contact with a planar waveguide. - Furthermore,
FIG. 3 of JP H11-202222A shows the transmissivity of light when evanescent light of light that is totally reflected by a total reflection surface is extracted at an extraction surface that has been brought in to proximity with the total reflection surface. According to this, transmissivity of approximately 50% is shown for light that has an incident angle in the range of 50° to 80° to the total reflection surface when the distance between the total reflection surface and the extraction surface is in the range of 0.1 to 0.05 μm. - Furthermore, for example, a display device is disclosed in “Waveguide Panel Display Using Electromechanical Spatial Modulators,” X. Zhou, E. Gulari, SID98 Digest, 1998, pages 1,022 to 1,025, in which an electrostatic actuator, in which a metal electrode film is formed on a polyimide film, is used as the actuator portion and an LED is used as the light source. In this display device, in contrast to the light extraction portion's width of 0.23 mm, the thickness of the waveguide is 0.5 mm. Furthermore, a surface of the waveguide is an ITO film, and the surface of the light extraction portion that comes into contact with the ITO film is made by forming a film doped with titanium dioxide particles, which affect the diffusion properties of the polyimide, on an electrode, such that this film becomes a composite material harder than polyimide.
- The above-described conventional display device has low efficiency in extracting from the waveguide the light that is propagated in the waveguide. Moreover, unless the light extraction portion exerts a large pressure on the waveguide, the extracted light has insufficient brightness and is uneven.
- The present invention has been devised to solve these issues, and it is an object thereof to provide a display element and a display device in which light propagated in a waveguide can be extracted with high efficiency from a lateral face of the waveguide.
- A display element according to the present invention is provided with a light source and a waveguide that propagates a light emitted from the light source, wherein the light propagated in the waveguide is extracted to the outside from a waveguide lateral face, and wherein the light is extracted out of the waveguide from the waveguide lateral face by changing a shape of the waveguide lateral face.
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FIG. 1 is a cross-sectional view showing a structure of a display element according to Embodiment 1 of the present invention. -
FIG. 2 is a perspective view showing a structure of a display device according to Embodiment 1 of the present invention. -
FIG. 3 is a block diagram showing a structure of a display device according to Embodiment 1 of the present invention. -
FIG. 4 is a cross-sectional view showing a structure of a display element according toEmbodiment 2 of the present invention. -
FIG. 5 is a cross-sectional view showing a structure of a display element according toEmbodiment 3 of the present invention. -
FIG. 6 is a perspective view showing a structure of a display device according toEmbodiment 3 of the present invention. -
FIG. 7 is a block diagram showing a structure of a display device according toEmbodiment 3 of the present invention. -
FIG. 8 is a cross-sectional view showing a structure of a display element according toEmbodiment 4 of the present invention. - A display device according to the present invention extracts, from a lateral face of a waveguide, light that is propagated in the waveguide by changing the shape of the waveguide lateral face, and therefore is capable of extracting propagated light with high efficiency. This makes possible a display that is bright and uniform.
- Furthermore, it is preferable that the display element is further provided with a plurality of actuators that change a shape of the waveguide, wherein the shape of the waveguide lateral face is changed by selectively operating the actuators to extract the light out of the waveguide from the waveguide lateral face. In this way, light propagated in the waveguide can be extracted with high efficiency.
- Furthermore, it is preferable that the waveguide is provided with a core and a cladding formed along one lateral face of the core, wherein the actuators are attached to the cladding and a shape of the waveguide lateral face is changed by deforming the actuators. In this way, light propagated in the waveguide can be extracted with high efficiency.
- Furthermore, it is preferable that the light is extracted out of the waveguide by deforming at least a portion of the core of the waveguide. In this way, light can be extracted precisely.
- Furthermore, it is preferable that the actuators are attached to the waveguide lateral face, and a shape of the waveguide lateral face is changed by deforming the actuators. In this way, light can be extracted easily.
- Furthermore, it is preferable that the actuators are provided with a piezoelectric element, and a shape of the waveguide lateral face is changed by deforming the piezoelectric element by applying a voltage to the piezoelectric element. In this way, actuators that operate at high speed can be formed and therefore high precision video display can be supported.
- Furthermore, it is preferable that the actuators are provided with a first electrode film arranged at the waveguide lateral face, a piezoelectric element layered on the electrode film, and a second electrode film layered on the piezoelectric element, wherein the shape of the waveguide lateral face is changed by deforming the piezoelectric element by applying a voltage between the first electrode film arranged at the waveguide lateral face and the second electrode film layered on the piezoelectric element. In this way, high efficiency light extraction can be achieved with small external pressure.
- Furthermore, it is preferable that the actuators are provided with a convex portion, and a shape of the waveguide lateral face is changed by applying pressure to the waveguide lateral face with the convex portion. In this way, high efficiency light extraction can be achieved easily.
- Furthermore, the actuators are provided with: an electrode film arranged at the waveguide lateral face, and an external electrode film that is in opposition to and adjacent to the waveguide, wherein the shape of the waveguide lateral face is changed by an electrostatic force produced by applying a voltage between the external electrode film and the electrode film. In this way, high efficiency light extraction can be achieved easily.
- The external electrode film is provided with a convex portion at the waveguide lateral face, and a shape of the waveguide lateral face is changed by the convex portion of the external electrode film applying pressure to the waveguide lateral face by using the electrostatic force. In this way, actuators that operate at high speed can be formed and therefore high precision video display can be supported.
- Furthermore, it is preferable that the light is extracted out of the waveguide by deforming at least a portion of the core of the waveguide. In this way, light can be extracted precisely.
- Furthermore, it is preferable that at least a portion of the waveguide is made of an elastic material. In this way, high efficiency light extraction is possible with small external pressure.
- Furthermore, it is preferable that at least a portion of the waveguide is made of a transparent gel. In this way, high efficiency light extraction is possible with small external pressure.
- Furthermore, it is preferable that the actuators are formed for each pixel. This makes possible a display using an active matrix.
- Furthermore, it is preferable that the waveguide is provided with a waveguide electrode film on the waveguide lateral face, an opposing electrode film that opposes the waveguide electrode film, and particles arranged between the waveguide electrode film and the opposing electrode film, wherein, by applying a voltage between the waveguide electrode film and the opposing electrode film, the particles and the waveguide electrode film are brought into contact such that the light is extracted out of the waveguide from the waveguide lateral face. With such a structure, the particles and the waveguide can be integrated by bringing the particle into contact with the waveguide electrode film, and the light can be extracted out of the waveguide from the waveguide lateral face by changing the shape of the waveguide lateral face. In this way, high efficiency light extraction is possible by applying only a very uniform and small pressure.
- Furthermore, it is preferable that the light is extracted out of the waveguide by deforming at least a portion of the core of the waveguide. In this way, light can be extracted precisely.
- Furthermore, it is preferable that the particle is electrically charged. In this way, it is possible to control the particle with an electrostatic force and therefore control can be achieved easily.
- Furthermore, it is preferable that the particle has a magnetic property. In this way, it is possible to control the particle with an electrostatic force and therefore control can be achieved easily.
- Furthermore, it is preferable that a surface tension of the waveguide electrode film and a surface tension of a surface of the particles are different from each other. In this way, it is easy to cause the particles to contact the waveguide electrode film. For this reason, contact and non-contact of the particles can be controlled with a low voltage.
- Furthermore, a coating material is applied to the waveguide electrode film. In this way, it is easy to cause the particles to contact the waveguide electrode film. For this reason, contact and non-contact of the particles can be controlled with a low voltage.
- Furthermore, it is preferable that the waveguide electrode film and the opposing electrode film are provided for each pixel. This makes possible display using an active matrix.
- Furthermore, the particle is fluorescent. In this way, it is possible to extract light of various wavelengths by varying the wavelength of the light from the light source.
- Furthermore, the light source emits ultraviolet light. In this way, it is possible to achieve RGB display even when the light source is one type of LED.
- Furthermore, the light source is a 3-color LED or a 3-color laser. In this way, the number of waveguides can be reduced.
- Furthermore, it is preferable that the display device according to the present embodiment is provided with: the above-described display element, the light source drive circuit for driving the light source, an actuator drive circuit for driving the actuator, and a control circuit that controls the light source drive circuit and the actuator drive circuit. In this way, it is possible to achieve a display device capable of higher luminance and uniform display with lower power consumption.
- Furthermore, it is preferably provided with the above-described display element, the light source drive circuit for driving the light source, a particle drive circuit for applying a voltage between the waveguide electrode film and the opposing electrode film, and a control circuit that controls the light source drive circuit and the particle drive circuit. In this way, it is possible to achieve a display device capable of higher luminance and uniform display with lower power consumption.
- Furthermore, it is preferably provided with the above-described display element and an active matrix element that controls the respective actuators. This achieves a display device using an active matrix.
- Furthermore, it is preferably provided with the above-described display element and an active matrix element that controls respective voltages between the waveguide electrode films and the opposing electrode films. This achieves a display device using an active matrix.
- Furthermore, the active matrix elements may be a TFT or a TFD.
- The following is a description of more specific examples of embodiments according to the present invention with reference to the accompanying drawings.
- The following is a description of a display element and a display device according to an embodiment of the present invention with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing a structure of a display element 1 according to Embodiment 1 of the present invention. The display element 1 is provided with alight source 2, awaveguide 3 that propagates the light emitted from thelight source 2, and a plurality ofactuators 4 that change the form of thewaveguide 3. - The
waveguide 3 is provided with acore 3 a, through which light propagates, and acladding 3 b. Thecladding 3 b is arranged along the surface on one side of thecore 3 a. Cladding is not arranged on the surface on the opposite side from thecladding 3 b such that air acts as the cladding there. A sheet of silicone gel, which is an extremely soft material, with a thickness of 100-μm for example may be used as thecore 3 a, through which light propagates. A transparent fluoric polymer for example with a low refractive index may be used as thecladding 3 b. Thecore 3 a is coated with thecladding 3 b to a thickness of 10 μm. - The
light source 2 is arranged at an end portion of thewaveguide 3 and thelight source 2 is arranged with an orientation such that the light emitted from thelight source 2 is coupled into thewaveguide 3. It is preferable that a 3-color LED for example is used as thelight source 2. The 3-color LED can have a structure in which RGB 3-color LED chips are accommodated in a single lamp, with each color independently controlled.. In conventional flat panel displays using LCD or PDP, the pixels of the three RGB colors are separated in a stripe form. However, in Embodiment 1, by using a 3-color LED, the light of the three colors R, G, and B can be input to asingle waveguide 3, and therefore it is possible for asingle waveguide 3 to emit any of the three colors R, G, and B. It should be noted that it is preferable for aprism 2 a to be placed and optically coupled at an incident location of thewaveguide 3 to facilitate entrance of the light from thelight source 2 even when thewaveguide 3 is thin. - The
actuators 4 are provided with apiezoelectric element 4 a, andelectrode films piezoelectric element 4 a. Theactuators 4 are attached at a lateral face on thecladding 3 b side of thewaveguide 3. Thepiezoelectric element 4 a may be polyvinylidene fluoride (PVDF) for example, on which a plurality of theelectrode films 4 b and theelectrode film 4 c are formed by applying on both sides thereof a silver paste for example. Theactuators 4 are attached with an adhesive at a lateral face, that is, thecladding 3 b, of thewaveguide 3. Theelectrode films 4 b have a width of 70 μm and are formed in a striped pattern with a pitch of 90 μm. It should be noted that these stripes are formed extending vertically with respect to the paper plane inFIG. 1 . Four of these stripes ofelectrode films 4 b constitute asingle actuator 4. Furthermore, theelectrode film 4 c facing theelectrode films 4 b is a continuous coating that spreads uniformly on thewaveguide 3 and is shared by a plurality ofactuators 4. - The following is a description of how light is extracted from a lateral face of the
waveguide 3 of the display element 1 shown inFIG. 1 . Positive and negative voltages are alternately applied to the four stripes ofelectrode films 4 b of theactuators 4 arranged at thewaveguide 3. In this way, thepiezoelectric film 4 a contracts in locations of theelectrode films 4 b supplied with a positive voltage, and thepiezoelectric film 4 a lengthens in locations of theelectrode films 4 b supplied with a negative voltage. Since the length of thecladding 3 b is prescribed and does not change, theactuators 4 alternately project up and down as shown inFIG. 1 . That is, theactuators 4 become wave shaped. This makes thecladding 3 b change to the same shape as theactuators 4 and the surface of thecore 3 a on thecladding 3 b side is also deformed. - The lengths of the
cladding 3 b and thepiezoelectric film 4 a are the same when no voltage is applied, and therefore theactuators 4 assume a planar shape. - In this way, it is possible to change the form of the lateral face of the
waveguide 3 by selectively controlling the voltage that is applied between theelectrode films 4 b and theelectrode film 4 c. - Light of a desired color emitted from the
light source 2 is propagated in thewaveguide 3. Here; when concavity and convexity are produced in desired locations on the surface of thecore 3 a on thecladding 3 b side in thewaveguide 3 by selectively applying voltages, a portion of the light propagated in thewaveguide 3, for example, alight 2 c shown as a dot-dash line, undergoes a change of angle with respect to the surface of thecore 3 a, and therefore is emitted out of thewaveguide 3 from a lateral face (the side on which actuators 4 of thewaveguide 3 are not arranged) of thewaveguide 3 after being totally reflected. Furthermore, alight 2 b, which is shown by a broken line, is transmitted through thecore 3 a and thecladding 3 b due to the changed form of thewaveguide 3 and is then reflected by thesilver electrode film 4 c such that it is scatter-reflected and emitted out of thewaveguide 3 from a lateral face of thewaveguide 3. - In this way, by controlling the application of voltages to control the color of emitted light from the
light source 2 that is incident on thewaveguide 3, it is possible to extract light at a desired position and of a desired color from the lateral face (display surface 1 a) of thewaveguide 3 of the display element 1 and carry out display. - Furthermore, the greater the voltage applied to the
actuators 4, the greater the change in form of thewaveguide 3. Increases in the luminance of the extracted light were observed according to measurements along with gradual increases in applied voltages starting from zero. Luminance was saturated when the voltage applied was ±30 volts and it was possible to extract 80% or more of the light from thelight source 2 that was incident on thewaveguide 3. - A
light source 2 that provides high directivity for emitted light is preferable for extracting light efficiently. In thewaveguide 3 of thedisplay surface 1 a inFIG. 1 , the total reflection angle at the interface between the core 3 a and the air is 60°. Accordingly, when the angle (incident angle) of the light propagated in thewaveguide 3 with respect to the normal line of the display surface la is smaller than 41.8°, which is the critical angle, light leaks from thewaveguide 3. Conversely, when the incident angle is large and the travel direction of the light is close to parallel to thewaveguide 3, total reflection occurs repetitively in thecore 3 a and the spacing between locations of such total reflection becomes extremely large such that locations in which light extraction is desired are passed over, thus tending to reduce efficiency and produce uneven luminance. - For these reasons, it is preferable that the incident angle of light emitted from the
light source 2 to thewaveguide 3 is larger than the critical angle of 41.8° but close to the critical angle of 41.8° with a light of high directivity. For example, when thelight source 2 is an LED, the directivity can be varied according to the shape of the lens that is molded, and therefore the half-value width of the emitted light angle distribution of the 3-color LED serving as thelight source 2 was set at approximately 10°. - It should be noted that it is possible to use a
light source 2 other than an LED. For example, it is possible to use alight source 2 in which directivity has been improved by arranging a micro-lens array on an organic EL panel and it is also possible to use a semiconductor laser as thelight source 2. - When the
waveguide 3 is too thick, the light propagated inside thewaveguide 3 undergoes repetitive total reflection at thedisplay surface 1 a (the interface between thewaveguide 3 and the air) and the spacing between locations of total reflection becomes extremely large. For this reason, the propagated light may pass over the arranged locations (pixels) of theactuators 4, thus bringing about light beams that cannot be extracted. Therefore, it is preferable that thewaveguide 3 is not too thick. - Specifically, setting the thickness D of the
waveguide 3 inFIG. 1 at not greater than ½ of the length L (the length of theactuators 4 in the propagation direction of light in the waveguide 3) of the portions of thewaveguide 3 that are made to change form by theactuators 4 is preferable in terms of efficient extraction. - The thickness of the
waveguide 3 is determined according to the number of pixels and the size of the display area. In the display element 1, the length L of the portions of thewaveguide 3 that are made to change form by theactuators 4 corresponds to the length of one pixel in the horizontal direction (propagation direction of light in the waveguide 3). For example, the display size of adisplay device 100 using the display element 1 described below is that of a HDTV in the range of 60 to 100 inches. In this case for example, the size of a single pixel is approximately in the range of 230.6 μm (vertical)×691.8 μm (horizontal) to 384.3 μm (vertical)×1,153 μm (horizontal). It should be noted that here vertical is the length in the perpendicular direction with respect to the propagation direction of length in thewaveguide 3 and horizontal is the length in the propagation direction of light in thewaveguide 3. The thickness D of thewaveguide 3 here is preferably not greater than 345.9 μm and not greater than 576.5 μm. The thickness D of thewaveguide 3 is preferably not greater than ½ of the length L (the length of theactuators 4 in the propagation direction of light in the waveguide 3) of the portions of thewaveguide 3 that are made to change form by theactuators 4. - On the other hand, when the
waveguide 3 is too thin, the angles at which light can be propagated in thewaveguide 3 are limited such that the propagated light is close to single mode, and therefore the amount of propagated light is reduced. Furthermore, it is difficult to provide incident light when thewaveguide 3 is too thin. For this reason, it is preferable that the thickness of thecore 3 a is at least 30 μm or more. - The following is a description of a
display device 100 according to Embodiment 1 with reference toFIG. 2 .FIG. 2 is a perspective view showing a structure of thedisplay device 100 according to Embodiment 1. With the above-described display element 1 vertical with respect to the propagation direction of light in thewaveguide 3, thedisplay device 100 can be configured by arranging in a row a plurality of the display elements 1 such that the display surfaces la are on the same side. As shown inFIG. 2 , with thedisplay device 100 of Embodiment 1, thewaveguides 3 of the display elements 1 are arranged in an array of n rows in the row direction (X direction) of the screen. Here, n is a natural number. Therespective light sources 2 are arranged at end portions of thewaveguides 3 andactuators 4 for m lines are arranged in a line direction (Y direction), which is the direction in whichwaveguides 3 extend. The number of pixels of thedisplay device 100 is n×m pixels. - A
display device 100 according to Embodiment 1 operates theactuators 4 in line sequence to change the form of the lateral face of thewaveguide 3 and thereby change the direction in which light conveyed in thewaveguide 3 by total reflection is reflected, thus extracting light from within thewaveguide 3 and causing the light emission from thedisplay surface 1 a. - A
display device 100 with this configuration is capable of displaying a given image by controlling the application of voltages to the various chips for the 3-color LEDs serving as thelight sources 2 for thewaveguides 3 that extend in the row direction of the display plane (XY plane), based on the color and luminance information of the pixels on the lines for which extraction is selected with theelectrode films 4 b and theelectrode film 4 c. - A block diagram showing a configuration of the
display device 100 of Embodiment 1 is shown inFIG. 3 .FIG. 3 illustrates a specific configuration for actually operating thedisplay device 100. In addition to the above, thedisplay device 100 is provided with a lightsource drive circuit 50 for driving thelight sources 2, anactuator drive circuit 51 for driving theactuators 4 by applying voltages to theelectrode film control circuit 52 that synchronizes these circuits, inputs signals, and displays images. Thecontrol circuit 52 inputs luminance information of the colors RGB of pixels in lines selected by theactuator drive circuit 51 to the driver LSI of the lightsource drive circuit 50, and the lightsource drive circuit 50 inputs applied voltages corresponding to the luminance information to thelight sources 2 to enable full color image display. - Since 3-color LEDs are used as the
light sources 2, it is possible to make light of three colors incident on asingle waveguide 3. This makes it possible to display light of three colors with a single display element 1, that is, with one line. With conventional display devices such as liquid crystal displays and PDPs, a pixel is configured by three sub-pixels of the three primary colors R, G, and B. However, with the display device using thewaveguide 3 of Embodiment 1, it is not necessary to divide thewaveguides 3 that extend in the row direction for each color and the three primary colors can be incident on asingle waveguide 3, and therefore it is possible to reduce the number of waveguides 3 (display elements 1), thus providing the effect of reduced costs. - Uniformly bright planar display could be confirmed by sequentially applying voltages of ±30V to the
actuators 4 in the display elements 1 of thedisplay device 100. With conventional structures in which light is extracted using evanescent waves, it has not been possible to reduce to zero the distance between the waveguide and the light extraction surface due to the influence of submicron size particulates that exist in multitude even in clean rooms. For this reason, it has not been easy to achieve high extraction efficiency even when pressing the light extraction surface against the waveguide with considerable force. - However, with the display elements 1 of the
display device 100 of Embodiment 1, by using soft waveguides, light is extracted by causing the waveguides to change form with small external force, thus changing the reflection direction of light propagated in the waveguides. For this reason, it was possible to achieve a higher extraction efficiency than using extraction of evanescent waves. - Furthermore, high speed operation is possible since piezoelectric elements are used in the
actuators 4. For this reason, high-speed scanning is possible, thus also supporting high-definition image display. - The following is a description of a display element 11 according to
Embodiment 2 of the present invention with reference toFIG. 4 . In the display element 11 ofEmbodiment 2 and the display element 1 of Embodiment 1, the actuators are different. Other than that the structure is substantially the same and therefore members having the same function will be given the same numerical symbol and description thereof will be omitted. - As shown in
FIG. 4 , the display element 11 ofEmbodiment 2 is provided with alight source 2, awaveguide 3 that propagates the light emitted from thelight source 2, andactuators 14 that change the form of thewaveguide 3. Thelight source 2 and thewaveguide 3 are the same as in the display element 1 of Embodiment 1. Thelight source 2 is a 3-color LED for example, and the light emitted by thelight source 2 propagates in thewaveguide 3. Thewaveguide 3 is provided with acore 3 a and acladding 3 b, and since thecore 3 a is exposed on the opposite side of thecladding 3 b, the air acts as cladding. It should be noted that inEmbodiment 2, thecore 3 a is a flat sheet of a 100 μm thickness and is made of a silicone gel material, while thecladding 3 b is a transparent fluoric resin with a film thickness of 5 μm. - The
actuators 14 are provided with anelectrode film 14 a arranged on a lateral face of thewaveguide 3, a polycarbonate insulationthin film 14 b of a thickness of 0.1 μm for example that is applied to theelectrode film 14 a, asubstrate 14 d made of 0.15 mm thick PET film arranged in opposition to the insulationthin film 14 b, andexternal electrode films 14 c, which are formed on thesubstrate 14 d on the insulationthin film 14 b side and have a concavo-convex shape. There are a plurality of the concavo-convex shapedexternal electrode films 14 c on thesubstrate 14 d, and asingle actuator 14 is configured for eachexternal electrode film 14 c. Theelectrode film 14 a is formed on the entire surface of the waveguide 3 (cladding 3 b) and is common with respect to theactuators 14. - A method for manufacturing the above-described
waveguide 3 and theactuators 14 is to coat thecladding 3 b on thecore 3 a for example, then further apply a silver paste with screen printing for example on the surface of thecladding 3 b to form theelectrode film 14 a. Further still, a polycarbonate is applied to theelectrode film 14 a to form the insulationthin film 14 b. Then, an indented concavo-convex portion 14 e is formed by being pressed formed in a striped pattern on the surface of thesubstrate 14 d, which is made of a 0.15 mm thick PET film. The concavo-convex portion 14 e has a cross-sectional depth of 3 μm for example and a pitch of 30 μm. The aluminumexternal electrode films 14 c are formed on the concavo-convex portion 14 e by carrying out aluminum deposition for example. Finally, thesubstrate 14 d and thewaveguide 3 are arranged so as to oppose each other. - The following is a description of the operation of the thus-structured display element 11.
- When no voltage is applied between the
electrode film 14 a and theelectrode film 14 b, only the convex portions of the concavo-convex shapedexternal electrode films 14 c and the insulationthin film 14 d are connected at the end portions of the display element 11 shown inFIG. 4 . For this reason, the lateral face of thewaveguide 3 is flat. However, by applying a voltage between theelectrode film 14 a and theexternal electrode films 14 c, an electrostatic force is produced therebetween such that these are attracted to each other. Due to this, as shown in the central area of the display element 11 shown inFIG. 4 , theelectrode film 14 a and theexternal electrode film 14 c cling toward each other and theelectrode film 14 a and theexternal electrode film 14 c are deformed to the same concavo-convex shape. Furthermore, theelectrode film 14 a is adhering to thewaveguide 3, and therefore thecladding 3 b and the surface of thecore 3 a are deformed to the same concavo-convex shape as theexternal electrode films 14 c. That is, the lateral face of thewaveguide 3 changes shape. It should be noted that thecore 3 a is particularly soft and therefore changes shape greatly. In this way, light that is being propagated while being totally reflected in thewaveguide 3 can be extracted to the outside from the lateral face of thewaveguide 3. As in Embodiment 1, a light 12 c that is being propagated while being totally reflected in thewaveguide 3 by the surfaces of thecore 3 a can be leaked to the outside from the lateral face of thewaveguide 3 by deforming the lateral face on one side of thewaveguide 3. - That is, when desired locations of the surface of the
core 3 a are made to deform to a concavo-convex shape, of the light that has been propagated in thewaveguide 3, the light 12 c shown by the one-dot dash line for example, is emitted out of thewaveguide 3 from the lateral face (the side on which theactuators 4 of thewaveguide 3 are not arranged) of thewaveguide 3 after being totally reflected since the angle of the surface of thecore 3 a changes. Furthermore, there is also light for example that penetrates thecore 3 a and thecladding 3 b and is then reflected by thesilver electrode film 14 a such that it is scatter-reflected and emitted out of thewaveguide 3 from a lateral face of thewaveguide 3. - In this way, by controlling the application of voltages to control the color of emitted light from the
light source 2 that is incident on thewaveguide 3, it is possible to extract light at a desired position and of a desired color from the lateral face (display surface 1 a) of thewaveguide 3 of the display element 1 and carry out display. - When sequential line scanning actually is carried out by introducing incident light to the
waveguide 3 from the 3-colorLED light source 2, applying +10V as a selective voltage between theelectrode film 14 a and theexternal electrode film 14 c, and applying 0V to a non-selective location, a uniformly bright display is achieved from the lateral face (display surface 1 a) of thewaveguide 3. Even at low voltages, it is possible to extract to the outside almost all the incident light of thelight source 2, thus achieving a display element 1 with high power efficiency. - A display device can be configured in the same way as the
display device 100 by arranging in a row a plurality of the display elements 11 shown inFIG. 4 vertical with respect to the propagation direction of light in thewaveguide 3, such that the display surfaces la are on the same side, as shown inFIG. 2 . The number of pixels when n rows of the display elements 11 are arranged in the row direction of the screen andactuators 14 for m lines are arranged in the direction (line direction) in which thewaveguides 3 extend is n×m pixels. - The method for achieving extraction from the lateral face (
display surface 1 a) of thewaveguide 3 to carry out image display is the same as for thedisplay device 100 of Embodiment 1, and therefore will not be further explained. Only the structure of the actuators is different between the display device of Embodiment 1 and the display device ofEmbodiment 2, and the rest of the structure is substantially the same. - Furthermore, in order to actually operate the display device of
Embodiment 2, it is sufficient to provide, as shown inFIG. 3 , a lightsource drive circuit 50 for driving thelight sources 2, anactuator drive circuit 51 for driving operating theactuators 14 by applying voltages to theelectrode films control circuit 52 that synchronizes these circuits, inputs signals, and displays images. - Since a light modulation medium is sandwiched between line electrodes and row electrodes in conventional XY matrix-type flat display elements, it was difficult to increase the size of the devices due to the occurrence of crosstalk. However, with the display devices of
Embodiment 1 and 2, there is no electrical connection between the drive circuits of the lines and rows, and therefore crosstalk essentially does not occur and, moreover, it is easy to increase the size of devices since the structure is simple. Moreover, since it is not particularly necessary to provide ITO, which requires high temperature processing and because the structure is simple, it is possible to achieve thin flexible display devices that resemble film. Furthermore, LEDs or the like with high light-emission efficiency are used as the light source, and therefore it is possible to achieve high light extraction efficiency with low power actuators, such that power consumption also can be reduced. - As described above, with a display element and a display device according to
Embodiment 1 and 2, by using a soft waveguide, it is possible to achieve a innovative display that has a large thin screen capable of being, hung or attached on a wall and that has high light emission efficiency and low power consumption. - It should be noted that in
embodiments 1 and 2, an example of silicone gel as thecore 3 a of thewaveguide 3 was described, but a transparent material that easily deforms and shows so called rubber elasticity, for example urethane based rubber will achieve the same effect. A material with a Young's modulus smaller than 106N/m2 may be used as thecore 3 a. - Furthermore, in
embodiments 1 and 2, theentire core 3 a was structured with the same material, but it is sufficient for the surface of thecore 3 a of thewaveguide 3 to be easily deformable, and therefore the surface on the side of thewaveguide 3 may be structured with a hard material such as an ordinary plastic while only locations to be deformed are structured as layers arranged by a soft layer. Furthermore, it is also possible to use awaveguide 3 in which only thecore 3 a is structured without thecladding 3 b such that the cladding on both sides is air. Furthermore, to facilitate handling, it is possible to use awaveguide 3 in which cladding is provided on both sides of thecore 3 a. - It should be noted that in
embodiments 1 and 2 a simple matrix type display device was shown in which thewaveguides 3 were arrayed according to the number of rows and a plurality of 3-colorLED light sources 2 were arranged, but the type of light source and the type of actuator, as well as the structure of the positioning of these is in no way limited to this. Any structure by which it is possible to achieve high extraction efficiency with low power by deforming asoft waveguide 3 may be used. For example, a structure is possible in which thewaveguide 3 is made of a single flat sheet with a singlelight source 2 arranged in an XY matrix with a number ofactuators actuators - With the display element and the display device according to
embodiments 1 and 2, the light extraction efficiency is improved in display elements and display devices that use a technique in which light propagated in thewaveguide 3 is extracted from the lateral face of the waveguide, which enables greater luminance with reduced power consumption as well as improved uniformity of display. Furthermore, it is possible to achieve sheet-shaped thin display devices regardless of the screen size even for large screens exceeding 100 inches and small screens for mobile applications. - The following is a description of a display element according to
Embodiment 3 of the present invention with reference toFIG. 5 .FIG. 5 is a cross-sectional view showing a structure of adisplay element 21 according toEmbodiment 3. As shown inFIG. 5 , thedisplay element 21 is provided with alight source 22, awaveguide 23, an opposingelectrode film 25 that opposes thewaveguide 23, andparticles 26 arranged near thewaveguide 23. - The
waveguide 23 is provided with a core 23 a that propagates light, acladding 23 b, andwaveguide electrode films 23 c. A sheet of acrylic resin for example, which is an extremely soft material, with a thickness of 100-μm is used as the core 23 a. Furthermore, a transparent fluoric polymer that has a low refractive index is coated as thecladding 23 b to a thickness of 10 μm on a surface on one side of the core 23 a. Thewaveguide electrode films 23 c are ITO and are attached directly with an adhesive on a surface on the opposite side of the core 23 a from thecladding 23 b. Thecladding 23 b is arranged on one surface only of the core 23 a and a plurality of thewaveguide electrode films 23 c are arranged on the reverse surface. Thewaveguide electrode films 23 c are ITO and a plurality of these are arranged in the direction in which thewaveguide 23 extends. The length W of thewaveguide electrode film 23 c in the propagation direction of light in thewaveguide 23 is 300 μm for example. The cladding on the opposite side of thecladding 23 b is air. Furthermore, thewaveguide electrode films 23 c are a portion of the core and the light propagated in thewaveguide 23 is also totally reflected by the interface of thewaveguide electrode films 23 c and the air. It should be noted that this also may be a structure in which nocladding 23 b is provided. - The
light source 22 is arranged at an end portion of thewaveguide 23 and thelight source 22 is arranged with an orientation such that the light emitted from thelight source 22 is coupled into thewaveguide 23. It is preferable that aprism 22 a is placed and optically coupled at an incident location of thewaveguide 23. It should be noted that thelight source 22 may be the same as thelight source 2 in Embodiment 1 and it is preferable that a 3-color LED is used for example. - A
light source 22 that has high directivity is preferable to enable efficient extraction of light from thewaveguide 23. In thewaveguide 23, the total reflection angle at the interface between the core 23 a and the air is 60°. The state of light propagation in thewaveguide 23 is shown conceptually in the cross-sectional view ofFIG. 5 . - When the incident angle (angle with respect to the normal line of the
display surface 21 a) to thewaveguide 23 of the light 22 b shown as a broken line emitted from thelight source 22 is smaller than 41.8°, which is the critical angle inEmbodiment 3, the light 22 b leaks from thewaveguide 23. Conversely, when the incident angle is greater than the critical angle of 41.8° as with the light 22 c shown by the dot-dash line, the travel path of the light 22 c is close to parallel to thewaveguide 23. In this way, total reflectance occurs repetitively in the core 23 a and thewaveguide electrode film 23 c and the spacing between locations of such total reflectance becomes extremely large such that locations in which light extraction is desired are passed over, thus tending to reduce efficiency and produce uneven luminance. Furthermore, as illustrated inFIG. 3 of JP H7-287176A, the extraction ratio of evanescent waves becomes smaller and efficiency is reduced. For these reasons, it is preferable that the incident angle of light emitted from thelight source 22 to thewaveguide 23 is larger than the critical angle of 41.8° but close to the critical angle of 41.8° with alight source 22 of high directivity. For example, when thelight source 22 is an LED, the directivity can be varied according to the shape of the lens that is molded, and is therefore preferable. That is why, inEmbodiment 3, a 3-color LED in which the half value width of the emitted light angle distribution is set to 10° is used as thelight source 22. - It should be noted that, other than an LED, it is also possible to use a light source whose directivity has been improved by arranging a micro-lens array on an organic EL panel, as the
light source 22, and it is also possible to use a semiconductor laser. By using 3-color LED as thelight source 22, it is easier to make light of three colors incident on asingle waveguide 23. With conventional displays such as liquid crystal displays and PDPs, a pixel is configured by three sub-pixels of the three primary colors R, G, and B, but by configuring a pixel as described above, it is not necessary to divide thewaveguides 23 that extend in the row direction for each color and the three primary colors can be incident on asingle waveguide 23. Therefore it is possible to reduce the number ofwaveguides 23, thus providing the effect of reduced costs. - The opposing
electrode film 24 is arranged in opposition to thewaveguide 23. The opposingelectrode film 24 is ITO for example, and is deposited on asubstrate 25 of an acrylic resin. The spacing between thewaveguide electrode film 23 c and the opposingelectrode film 24 is 35 μm for example. -
Particles 26 are arranged in the vicinity of thewaveguide 23. Theparticles 26 are positioned between thewaveguide electrode film 23 c and the opposingelectrode film 24, are made of an acrylic resin, and are electrically charged. The mean particle size of theparticles 26 is 6 μm for example. Theparticles 26 are filled into the space between thewaveguide electrode film 23 c and the opposingelectrode film 24 to a filling rate of 20%. It should be noted that the filling rate is the ratio of the volume occupied by the particles per unit of volume. The volume occupied by theparticles 26 can be obtained by multiplying the number ofparticles 26 per unit of volume by the volume per particle that is obtained from the mean particle size of theparticles 26. - When applying a voltage of 70V for example so that the selected
waveguide electrode film 23 c becomes negative and the opposingelectrode film 24 becomes positive, theparticles 26 contact the surface of thewaveguide electrode film 23 c. In this way, theparticles 26 and thewaveguide 23 become integrated. That is, theparticles 26 become a portion of a lateral face of thewaveguide 23 and the shape of the lateral face of thewaveguide 23 on the side of thewaveguide electrode film 23 c is changed. - Light of a desired color emitted from the
light source 22 is propagated in thewaveguide 23. Here, by selectively applying voltages to thewaveguide electrode film 23 c and the opposingelectrode film 24, the shape of the lateral face of thewaveguide 23 on the side of thewaveguide electrode film 23 c is changed by theparticles 26. By changing the shape of thewaveguide 23, the state of propagation changes and the light that has been propagated in thewaveguide 23 leaks outside from the waveguide lateral face of thewaveguide 23. By setting the refractive index of theparticles 26 to approximate the refractive index of the core 23 a or thecladding 23 b, it is possible to extract light to the outside from theparticles 26. It is preferable that the refractive index of theparticles 26 for example is substantially equivalent to the refractive index of the core 23 a. - In this way, light leaks from the contacting portions of the
particles 26 and thewaveguide electrode film 23 c, and therefore light can be extracted in the direction of theacrylic resin substrate 25 such that thesubstrate 25 can be made a display screen. - On the other hand, when a voltage of 70V is applied to reverse the electric field, that is, such that the
waveguide electrode film 23 c becomes positive and the opposingelectrode film 24 becomes negative, theparticles 26 move away from thewaveguide electrode film 23 c. For this reason, the light being propagated inside thewaveguide 23 cannot be extracted as leaked light and is guided as it is within thewaveguide 23, and therefore display is not conducted. - In this way, since light is extracted from the lateral face of the
waveguide 23 by bringingindividual particles 26 into contact with thewaveguide electrode film 23 c, the contact surface area is small and it is not necessary to have contact within the entire surface such as with conventional flat shaped piezoelectric elements. For this reason, a very uniform small pressure can be applied to thewaveguide 23 and, moreover, the pressure can be applied electrostatically to make control possible. It should be noted that in the above description chargedparticles 26 were used, but instead of these it is also possible to use particles that are magnetic and to control contact and non-contact of theparticles 26 to the surface of thewaveguide 23 by controlling a magnetic field between the opposingelectrode film 24 and thewaveguide electrode film 23 c. - Furthermore,
particles 26 made of an acrylic resin containing rhodamine, which is a fluorochrome, may be used as theparticles 26. In this case, the light extracted from the lateral face of thewaveguide 23 when using a green LED that emits a 520 nm wavelength light as thelight source 22 was observed to be an orange light with a wavelength of 580 nm. In this way, by selectively usingparticles 26 that contain a fluorochrome or a fluorescent substance, and anLED light source 22 that corresponds to the excitation wavelength of the fluorochrome or the fluorescent substance, it is possible to extract light, of various wavelengths. Furthermore, by using an ultraviolet light LED as thelight source 22 and by using the fluorescent substances used in PDPs as theparticles 26, it is possible to achieve display of RGB even when using a single color LED as thelight source 22. - The following is a description of a
display device 300 according toEmbodiment 3 with reference toFIG. 6 .FIG. 6 is a perspective view showing a structure of thedisplay device 300 according toEmbodiment 3. Thedisplay device 300 can be configured by arranging a plurality of the above-describeddisplay elements 21 in a row vertically with respect to the propagation direction of light in thewaveguide 23. As shown inFIG. 6 , with thedisplay device 300 ofEmbodiment 3, thewaveguides 23 of thedisplay elements 21 are arranged in an array of n rows in the row direction (X direction) of the screen. It should be noted that n is a positive integer. Thelight sources 22 are arranged respectively at end portions of thewaveguides 23. At the lateral face of thewaveguide 23, theelectrode films 23 c for m lines are arranged in the line direction (Y direction), which is the direction in which waveguides 23 extend. The opposingelectrode film 24 for thedisplay elements 21 is common and is arranged such that it covers all thewaveguides 23 of thedisplay elements 24. Furthermore, also thewaveguide electrode films 23 c of the same line are shared by therespective waveguides 23 and cover the lines thereof. The number of pixels of thedisplay device 300 is n×m pixels. - With the
display device 300 ofEmbodiment 3, theparticles 26 are made to undergo contact or non-contact to thewaveguide electrode film 23 c by controlling, line by line, the voltages applied between thewaveguide electrode film 23 c and the opposingelectrode film 24 such that light propagated in thewaveguide 23 by total reflection is extracted from a lateral face of thewaveguide 23 and emitted toward the opposingelectrode film 24. - A
display device 300 configured in this way is capable of displaying a given image by controlling the application of voltages to the various chips for the 3-color LEDs for thewaveguides 23 that extend in the row direction of the display plane (XY plane), based on the color and luminance information of the pixels on the lines for which extraction is selected with thewaveguide electrode film 23 c and the opposingelectrode film 24. - A block diagram showing a configuration of the
display device 300 ofEmbodiment 3 is shown inFIG. 7 .FIG. 7 illustrates a specific configuration for actually operating thedisplay device 300. In addition to the above, thedisplay device 300 is provided with a lightsource drive circuit 60 for driving thelight sources 22, aparticle drive circuit 61 for making theparticles 26 undergo contact or non-contact with thewaveguide electrode film 23 c by applying voltages to thewaveguide electrode film 23 c and the opposingelectrode film 24, and acontrol circuit 62 that synchronizes these circuits, inputs signals, and displays images. Thecontrol circuit 62 inputs luminance information of the colors RGB of pixels in lines selected by theparticle drive circuit 61 to the driver LSI of the lightsource drive circuit 60, and the lightsource drive circuit 60 inputs applied voltages corresponding to the luminance information to thelight sources 22 to enable full color image display. - Since 3-color LEDs are used as the
light sources 22, it is possible to make light of three colors incident on a single waveguide 33. This makes it possible to display light of three colors with asingle display element 21, that is, with one line. With conventional display devices such as liquid crystal displays and PDPs, a pixel is configured by three sub-pixels of the three primary colors R, G, and B. However, with the display device using thewaveguide 23 ofEmbodiment 3, it is not necessary to divide thewaveguides 3 that extend in the row direction for each color and the three primary colors can be incident on asingle waveguide 23. Therefore it is possible to reduce the number of waveguides 23 (display elements 21), thus providing the effect of reduced costs. - The following is a description of a
display element 31 according toEmbodiment 4 of the present invention with reference toFIG. 8 . Thedisplay element 31 according toEmbodiment 4 is a structure in which acoating material 37 that has a relatively large surface tension is applied on thewaveguide 23 of thedisplay element 21 according toEmbodiment 3, on the side on which thewaveguide electrode film 23 c is arranged. Specifically, the surface tension of thecoating material 37 is preferably not less than 50 mN/m. Thecoating material 37 covers the core 23 a and thewaveguide electrode film 23 c such that thecoating material 37 is a portion of the core, and the light propagated in thewaveguide 23 is also totally reflected by the interface of thecoating material 37 and the air. Since the same function is indicated for portions other than thecoating material 37, the same numerical symbols will be used and their further description will be omitted. - The
coating material 37 is a glycerin for example with a surface tension of 63.4 mN/m and is applied to have a thickness of approximately 2 μm. Furthermore, it is preferable that a material with a small surface tension is used for theparticles 26. Specifically, the surface tension of theparticles 26 is preferably not more than 30 mN/m. - A
display element 31 was actually formed using theparticles 26 made of Teflon (registered trademark) with a surface tension of 18.4 mN/m, for example. The mean particle size of theparticles 26 was set at 6 μm and the filling rate of theparticles 26 in the space between thewaveguide electrode film 23 c and the opposingelectrode film 24 was set at 20%. A voltage of 50V was applied so that thewaveguide electrode film 23 c of the selected line became negative and the opposingelectrode film 24 became positive. In this way, theparticles 26 came in contact with the surface of thewaveguide electrode film 23 c and the leaked light from the contact portion was extracted toward thesubstrate 25. On the other hand, a voltage of 50V was applied to reverse the electric field, namely so that thewaveguide electrode film 23 c became positive and the opposingelectrode film 24 became negative. In this way, since theparticles 26 move away from the surface of thewaveguide electrode film 23 c, the light from thelight source 22 propagated in thewaveguide 23 cannot be extracted as leaked light. In this case, display and non-display can be switched by a small voltage in thedisplay element 31 ofEmbodiment 4. This is because the surface tension of the glycerin, which is thecoating material 37 is sufficiently larger than the surface tension of the Teflon (registered trademark) of theparticles 26. In this way, the so called springiness at the contact surface between theparticles 26 and thecoating material 37 becomes greater. Springiness is a physical phenomenon in which springing occurs without thecoating material 37 spreading against surface of theparticles 26. That is, the greater the springiness between theparticles 26 and thecoating material 37, the greater the rebound at contact between theparticles 26 and thewaveguide electrode film 23 c. For this reason, theparticles 26 can be made to move away more easily from thewaveguide electrode film 23 c. Accordingly, contact and non-contact between theparticles 26 and, thewaveguide electrode film 23 can be controlled with a low voltage. - In this way, by providing the
coating material 37 with a different surface tension from theparticles 26 on the surface of the core 23 a and thewaveguide electrode film 23 c, it is possible to reduce the voltage required to control contact of theparticles 26. It should be noted that the surface tension of theparticles 26 may be different from the surface tension of the surface of the waveguide 23 (thewaveguide electrode film 23 c). However, generally the structure is such that the surface tension of theparticles 26 is smaller than the surface tension of the surface of thewaveguide 23. - A display device can be configured in the same way as the
display device 300 by arranging in a row a plurality of thedisplay elements 31 shown inFIG. 8 vertical with respect to the propagation direction of light in thewaveguide 23, such that the display surfaces 21 a are on the same side, as shown inFIG. 6 . When n rows of thedisplay elements 31 are arranged in the row direction of the screen and thewaveguide electrode film 23 c for m lines are arranged in the direction (line direction) in which thewaveguides 3 extend the number of pixels is n×m pixels. - The method for achieving extraction of a desired light from the lateral face (
display surface 21 a) of thewaveguide 23 to carry out image display is the same as for thedisplay device 300 ofEmbodiment 3, and therefore its explanation will be omitted. A point of difference between the display device ofEmbodiment 4 and the display device of Embodiment 5 is that thecoating material 37 is arranged on a surface of thewaveguide 23 and otherwise the structures are substantially the same. - Furthermore, in order to actually operate the display device of
Embodiment 4, as shown inFIG. 7 , it is possible to provide a lightsource drive circuit 60 for driving thelight sources 22, aparticle drive circuit 61 for making theparticles 26 undergo contact or non-contact to thewaveguide electrode film 23 c by applying voltages to thewaveguide electrode film 23 c and the opposingelectrode film 24, and acontrol circuit 62 that synchronizes these circuits, inputs signals, and displays images. - With the display devices of
Embodiment light sources 22 for thewaveguides 23 that extend in the row direction of the display plane (XY plane), based on the color and luminance information of the pixels on the lines for which extraction is selected with thewaveguide electrode film 23 c and the opposingelectrode film 24. However, the configuration of the type of light source and the positioning for example is not limited to these. For example, a structure is possible in which thewaveguide electrode film 23 c and the opposingelectrode film 24 are arranged in an XY matrix corresponding to the number of pixels. In this case, each pixel may be driven by connecting an active element to thewaveguide electrode film 23 c and the opposingelectrode film 24. A TFT or a TFD may be used as the active element for example. - With the display element and the display device according to
embodiments embodiments - The present inventors produced a display device in which light is extracted from a waveguide with a structure that is the same as the conventional structure of the previously mentioned “Waveguide Panel Display Using Electromechanical Spatial Modulators,” X. Zhou, E. Gulari, SID98 Digest, 1998, pages 1,022 to 1,025. However, it was evident that luminance was low and brightness is increased as thickness is reduced in conventional structures in which the thickness of the waveguide is thicker than the pixel width (width of propagation direction of light).
- The reason for this is that the distance between locations of total reflection in the waveguide in which propagated light undergoes repetitive total reflection at the interface between the core and the air is dependent on the thickness of the waveguide. For example, for total reflection at a reflection angle of 45°, the distance between locations of total reflection is double the width of the waveguide. And for this reason the thickness of the waveguide must be not greater than ½ of the width of the pixels in the light propagation direction. If not, the distance between locations of total reflection becomes greater than the pixel width and the reflected light passes over the pixels such that extraction from the waveguide lateral face cannot be achieved.
- Accordingly, from the point of view of extraction efficiency, the thickness of the waveguide in the display element of embodiments 1 to 4 is preferably less than ½ of the pixel width and, moreover, in consideration of the angle distribution of the incident light, it is more preferably thinner still. It should be noted that, specifically, the pixel width is the length of the
electrodes waveguide 3 inFIGS. 1 and 2 for the display elements ofembodiments 1 and 2, and is the length in the longitudinal direction of thewaveguide electrode film 23 c orwaveguide 23 inFIGS. 5 and 6 forembodiments - For example, when the thickness of the
waveguide waveguides waveguide waveguide waveguide - It should be noted that a 3-color laser (RGB) for example may be used for the
light sources - A display element and a display device of the present invention can be used in sheet-shaped thin display devices regardless of the screen size even for large screens and small screens for mobile applications.
Claims (21)
1. A display element comprising a light source and a waveguide that comprises a deformable core and propagates a light emitted from the light source, wherein the light propagated in the waveguide is extracted to outside the display element from a waveguide lateral face,
the display element further comprising a plurality of actuators that deform a shape of the waveguide,
wherein the actuators are attached to the waveguide lateral face,
wherein the shape of the waveguide lateral face is changed by deformation of the actuators, and
wherein the actuators are operated selectively to deform a surface shape of at least a portion of the core on the waveguide lateral face to a concavo-convex shape, and the surface of the core deformed to the concavo-convex shape reflects the light propagated in the waveguide toward a direction that extracts the light out of the display element from the waveguide lateral face.
2. (canceled)
3. The display element according to claim 1 , wherein the waveguide comprises a cladding formed along one lateral face of the core,
wherein the actuators are attached to the cladding and the shape of the waveguide lateral face is changed by deforming the actuators.
4. (canceled)
5. (canceled)
6. The display element according to claim 1 , wherein the actuators comprise a piezoelectric element, and
wherein the shape of the waveguide lateral face is changed by deforming the piezoelectric element by applying a voltage to the piezoelectric element.
7. The display element according to claim 1 , wherein the actuators comprise: a first electrode film arranged at the waveguide lateral face,
a piezoelectric element layered on the first electrode film, and
a second electrode film layered on the piezoelectric element,
wherein the shape of the waveguide lateral face is changed by deforming the piezoelectric element by applying a voltage between the first electrode film arranged at the waveguide lateral face and the second electrode film layered on the piezoelectric element.
8. The display element according to claim 1 , wherein the actuators comprise a convex portion, and
wherein the shape of the waveguide lateral face is changed by applying pressure to the waveguide lateral face with the convex portion.
9. The display element according to claim 1 , wherein the actuators comprise: an electrode film arranged at the waveguide lateral face, and
an external electrode film that is in opposition to and adjacent to the waveguide,
wherein the shape of the waveguide lateral face is changed by an electrostatic force produced by applying a voltage between the external electrode film and the electrode film.
10. The display element according to claim 9 , wherein the external electrode film comprises a convex portion at the waveguide lateral face, and a shape of the waveguide lateral face is changed by the convex portion of the external electrode film applying pressure to the waveguide lateral face by using the electrostatic force.
11. (canceled)
12. The display element according to claim 1 , wherein at least a portion of the waveguide comprises an elastic material.
13. The display element according to claim 1 , wherein at least a portion of the waveguide comprises a transparent gel.
14. The display element according to claim 1 , wherein the actuators are formed for each of a plurality of pixels.
15-23. (canceled)
24. The display element according to claim 1 , wherein the light source is a 3-color LED or a 3-color laser.
25. A display device comprising:
the display element according to claim 1 ,
a light source drive circuit for driving the light source,
an actuator drive circuit for driving the actuators, and
a control circuit that controls the light source drive circuit and the actuator drive circuit.
26. (canceled)
27. A display device comprising:
the display element according to claim 14 , and
an active matrix element that controls the respective actuators.
28. (canceled)
29. The display device according to claim 27 , wherein the active matrix element is a TFT or a TFD.
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- 2003-11-04 JP JP2005502151A patent/JP4054825B2/en not_active Expired - Fee Related
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2007
- 2007-04-09 US US11/784,617 patent/US20070189667A1/en not_active Abandoned
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Also Published As
Publication number | Publication date |
---|---|
JP4054825B2 (en) | 2008-03-05 |
KR20050073596A (en) | 2005-07-14 |
JPWO2004042449A1 (en) | 2006-03-09 |
EP1562065A1 (en) | 2005-08-10 |
TW200413776A (en) | 2004-08-01 |
US20060034566A1 (en) | 2006-02-16 |
US7236663B2 (en) | 2007-06-26 |
WO2004042449A1 (en) | 2004-05-21 |
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Legal Events
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |