JP2004205974A - Two-dimensional matrix element, and two-dimensional matrix plane display element and its driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a two-dimensional matrix plane display element which is low in driving voltage, can easily be increased in area at low cost, and has easy-to-manufacture constitution. <P>SOLUTION: The two-dimensional matrix plane display element is constituted by arranging a plurality of striped thin-film light sources emitting monochromatic light on a substrate, arranging a plurality of striped linear optical modulation arrays electromechanically controlling transmissivity to the light from the thin-film light sources thereupon orthogonally to the striped thin-film light sources, and providing filters having at least a wavelength converting function corresponding to pixels in front of an optical path including the linear optical modulation arrays. The two-dimensional matrix plane display element uses organic EL as the thin-film light sources and also uses the principle that a flexible thin film is displaced with static electricity as the linear optical modulation arrays. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a two-dimensional matrix device used as a thin flat display device, a micro display (ultra-small display), a two-dimensional matrix exposure device (mainly for sensitive material exposure sensitive to visible light, etc.), particularly mainly visible. The present invention relates to a two-dimensional matrix flat display element that emits light and a driving method thereof.
[0002]
[Prior art]
Conventionally, various types of thin flat display devices have been proposed, and typical ones include, for example, a liquid crystal display device using a liquid crystal electro-optic effect, a plasma display device, a field emission display, an organic electroluminescence, Examples include inorganic electroluminescence.
[0003]
In a liquid crystal display (LCD), nematic liquid crystal that is aligned so that the polarization axis is twisted by 90 ° between the substrates and parallel to the substrates is inserted and sealed between the substrates on which a pair of conductive transparent films are formed. And has a structure in which this is sandwiched between orthogonal polarizing plates. The display using this liquid crystal display device utilizes the fact that by applying a voltage to the conductive transparent film, the major axis direction of the liquid crystal molecules is aligned perpendicular to the substrate, and the transmittance of light from the backlight changes. Done. An active matrix liquid crystal panel using TFTs (thin film transistors) is used to provide good moving image compatibility.
[0004]
In a plasma display device (PDP), a large number of discharge electrodes are arranged between two glass plates filled with a rare gas such as neon, helium, or xenon so that the opposing electrodes are orthogonal to each other. It has a structure in which the intersection of each counter electrode is a unit pixel. The display by the plasma display device is based on image information, by selectively applying a voltage to the counter electrode that identifies each intersection, thereby causing the intersection to discharge light and exciting the phosphor with the generated ultraviolet rays. This is done by emitting light.
[0005]
A field emission display (FED) has a structure as a flat display rod in which a pair of panels are arranged to face each other with a minute interval and the periphery of these panels is sealed. A fluorescent film is provided on the inner surface of the panel on the display surface side, and a field emission cathode is arranged for each unit light emitting region on the rear panel. A typical field emission cathode has a conical-projection field emission type microcathode called a micro-sized emitter tip. The display by the FED is performed by extracting electrons using an emitter tip and irradiating the phosphor with acceleration to excite the phosphor to emit light.
[0006]
Organic electroluminescence (EL) can easily cover the entire visible range by selecting an organic material to be used as a light-emitting material. In recent years, many high-brightness and high-efficiency materials have been developed and actively researched. It has been broken. The device life has exceeded 10,000 hours in continuous operation and has been put into practical use as a color display.
[0007]
Inorganic electroluminescence (EL) utilizes collision excitation by an electric field, and has been actively studied as a small display or a large and light flat display. A monochrome thin film EL display using a phosphor thin film made of manganese-doped zinc sulfide emitting yellow-orange light has already been put into practical use.
[0008]
However, the above-described conventional flat display device has various problems described below.
In the LCD, since the light from the backlight is transmitted through multiple layers of a polarizing plate, a transparent electrode, and a color filter, there is a problem that the light use efficiency is lowered. In addition, a high-quality TFT requires a high-cost TFT, and there is a drawback that it is difficult to increase the area because liquid crystal must be sealed between two substrates and aligned. Further, since light is transmitted through the aligned liquid crystal molecules, there is a drawback that the viewing angle is narrowed. In particular, it has been difficult to completely correct the viewing angle dependency of the intermediate color.
[0009]
In the PDP, the manufacturing cost is increased due to the formation of a partition for generating plasma for each pixel, and there is a disadvantage that the weight is increased. In addition, a large number of electrodes corresponding to the discharge electrodes must be regularly arranged for each unit pixel. For this reason, when it becomes high definition, the light emission (discharge) efficiency is reduced, and the luminous efficiency of the phosphor by the vacuum ultraviolet excitation is low, so that it is difficult to obtain a high-definition and high-luminance image with high power efficiency. Furthermore, there is a drawback that the drive voltage is high and the drive IC is expensive.
[0010]
In the FED, in order to stabilize the discharge with high efficiency, it is necessary to set the inside of the panel to an ultra-high vacuum, and there is a drawback that the manufacturing cost becomes high like the plasma display device. In addition, since the electrons emitted from the field are accelerated to irradiate the phosphor, there is a disadvantage that a high voltage is required.
[0011]
In an organic EL, a low-temperature polysilicon TFT is required to produce a large-area display screen of 10 inches or more with an active matrix, so that the cost is high and display uniformity is not good.
[0012]
Inorganic EL has low luminous efficiency, high cost, requires a high-voltage driving IC circuit, and lacks performance. In addition, thin-film EL displays using sulfide phosphor thin films are excellent in reliability and environmental resistance, but at present, the characteristics of EL phosphors that emit light in the three primary colors of red, green, and blue are sufficient. Therefore, full color is not suitable.
[0013]
In addition, multi-colored light is produced by using blue excitation light as a backlight, transmitting blue light as it is through a liquid crystal switch and using it as blue, and simultaneously emitting green and red light with a filter having a color conversion function. A display is disclosed (for example, see Patent Document 1).
However, in this liquid crystal switch display, polarizing plates are used on both sides of the liquid crystal, and if the phosphor is put inside the polarizing plate, light is scattered and depolarized, so the phosphor is outside the polarizing plate. Therefore, light that enters obliquely with respect to the glass has a large glass thickness, so it irradiates the adjacent pixel instead of the pixel directly above, and the optical path other than collimated light (straight-ahead light) There is a drawback that the pixel shifts and the pixel shift is likely to occur.
[0014]
[Patent Document 1]
JP 2001-83501 A
[0015]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and provides a two-dimensional matrix element that has a low driving voltage and can be enlarged at a low cost and is easy to manufacture. Further, it has high image quality and high-speed response. An object of the present invention is to provide a two-dimensional matrix flat display element having the above-described structure.
[0016]
[Means for Solving the Problems]
To achieve the above object, a plurality of striped thin-film light sources that emit monochromatic light on a substrate and a striped light modulation element array are provided so as to be orthogonal thereto, and the light modulation element array is electromechanically Since the transmittance of light from the light source is controlled, the drive voltage is low, inexpensive, lightweight, easy to increase in area, easy to manufacture, and has high image quality and fast response. The flat display element which has is obtained.
[0017]
That is, in the two-dimensional matrix device according to the first aspect of the present invention, a plurality of striped thin-film light sources that emit monochromatic light are arranged on a substrate, and the light transmittance from the thin-film light sources is measured on the substrate. A plurality of striped one-dimensional light modulation arrays that are mechanically controlled are arranged so as to be orthogonal to the striped thin film light sources.
[0018]
The two-dimensional matrix flat display element according to claim 2 has a plurality of striped thin-film light sources that emit monochromatic light on a substrate, and the transmittance of light from the thin-film light sources is electromechanically disposed thereon. A plurality of stripe-shaped one-dimensional light modulation arrays to be controlled are arranged so as to be orthogonal to the stripe-shaped thin film light source, and a filter having at least a wavelength conversion function is provided in the pixel in front of the optical path including the one-dimensional light modulation array. It is characterized by being provided in correspondence.
[0019]
The two-dimensional matrix flat display element according to claim 3 is characterized in that the thin film light source is an organic EL.
[0020]
The two-dimensional matrix flat display element described in claim 4 is characterized in that a filter having a wavelength conversion function is arranged apart from the one-dimensional light modulation array.
[0021]
The two-dimensional matrix flat display element according to claim 5 is characterized in that a filter having a wavelength conversion function is provided in contact with or in the one-dimensional light modulation array.
[0022]
The two-dimensional matrix flat display element according to claim 6 is characterized in that the main wavelength of light from the thin film light source is 350 nm to 400 nm.
[0023]
The two-dimensional matrix flat display element according to claim 7, wherein the filter having a wavelength conversion function includes a fluorescent material that emits light in a color including red and / or green and / or blue with respect to light source light. And
[0024]
The two-dimensional matrix flat display element according to claim 8, wherein the red and / or red light that is transmitted from at least a part of the light source light and emitted from the fluorescent material between the filter having a wavelength conversion function and the one-dimensional light modulation array. A second filter that reflects light of a color including green and / or blue is provided.
[0025]
The two-dimensional matrix flat display element according to claim 9 is characterized in that a main wavelength of light from a thin film light source is 400 nm to 520 nm.
[0026]
The two-dimensional matrix flat display element according to claim 10 is characterized in that the filter having a wavelength conversion function includes a fluorescent material that emits light in a color including red and / or green with respect to the light source light.
[0027]
The two-dimensional matrix flat display element according to claim 11 is characterized in that the filter having a wavelength conversion function has a function of transmitting red and / or green light.
[0028]
The two-dimensional matrix flat display element according to claim 12 is provided with a third filter corresponding to a pixel, in front of an optical path including the one-dimensional light modulation array, having a function of transmitting blue light with respect to light source light. It is characterized by that.
[0029]
The two-dimensional matrix flat display element according to claim 13 has a function of transmitting blue light, but has a fluorescent material that emits light in a color including blue with respect to light source light.
[0030]
The two-dimensional matrix flat display element described in claim 14 has a function of transmitting blue light, but has a light diffusion function.
[0031]
The two-dimensional matrix flat display element according to claim 15 has an ND film or a polarizing film for attenuating external light in front of a filter having a wavelength conversion function.
[0032]
The two-dimensional matrix flat display element according to claim 16 is characterized in that the one-dimensional light modulation array uses a principle that the flexible thin film is displaced by static electricity.
[0033]
The two-dimensional matrix flat display element according to claim 17 is characterized in that the one-dimensional light modulation array controls light transmittance by changing an optical path opening area by displacement of the flexible thin film. .
[0034]
19. The two-dimensional matrix flat display element according to claim 18, wherein the one-dimensional light modulation array moves the coupling element by the displacement of the flexible thin film, and controls the light transmittance by the transmission of the proximity light and the light blocking by the total reflection. It is characterized by being.
[0035]
The two-dimensional matrix flat display element according to claim 19 is characterized in that the one-dimensional light modulation array is of a backlight incident type, and an optical path selection film is disposed on the thin film light source.
[0036]
21. The two-dimensional matrix flat display element according to claim 20, wherein a thin film light source and at least a part of incident light on the surface from the thin film light source arranged from the thin film light source disposed so as to face the thin film light source are totally reflected. The total reflection optical member provided with a total reflection surface on the other surface in front of the optical path, and a desired position of the total reflection surface of the total reflection optical member close to the desired position of the total reflection surface. The one-dimensional light modulation array is provided, which is provided so that the total reflection condition of incident light on the total reflection surface is broken and incident light is combined and extracted from the total reflection surface.
[0037]
The two-dimensional matrix flat display element according to claim 21 is characterized in that the total reflection optical member has an optical element that changes an optical path of incident light on the surface.
[0038]
The two-dimensional matrix flat display element according to claim 22 is characterized in that the total reflection optical member has an optical element for selecting an optical path of incident light on the surface.
[0039]
The two-dimensional matrix flat display element according to claim 23, wherein the total reflection optical member selects an optical element for changing an optical path of the incident light and an optical path of the incident light from the incident light introduction side on the surface. It is characterized by having optical elements in this order.
[0040]
A two-dimensional matrix flat display element according to a twenty-fourth aspect is characterized in that the one-dimensional light modulation array has optical path changing means for changing the optical path of the extracted light.
[0041]
The two-dimensional matrix flat display element according to claim 25 is characterized in that the optical path changing means changes the optical path of the extracted light by refraction.
[0042]
A two-dimensional matrix flat display element according to a twenty-sixth aspect is characterized in that the optical path changing means includes any one of a lens array, a prism array, and a gradient index lens body.
[0043]
The two-dimensional matrix flat display element according to claim 27 is characterized in that the optical path changing means changes the optical path of the extracted light by diffraction.
[0044]
A two-dimensional matrix flat display element according to a twenty-eighth aspect is characterized in that the optical path changing means includes any one of a volume hologram, a phase modulation type diffraction grating, and an amplitude modulation type diffraction grating.
[0045]
A two-dimensional matrix flat display element according to a twenty-ninth aspect is characterized in that the optical path changing means changes the optical path of the extracted light by light diffusion or light scattering.
[0046]
In the two-dimensional matrix flat display element according to claim 30, the optical path changing means is any one of a porous body, a different refractive index dispersion or distribution body, or a light diffuser or light scatterer having irregularities on the surface. It is characterized by that.
[0047]
A two-dimensional matrix flat display element according to a thirty-first aspect is characterized in that a scanning signal is supplied to a thin film light source and an image signal is supplied to a one-dimensional light modulation array.
[0048]
33. The driving method for a two-dimensional matrix flat display element according to claim 32, wherein a scanning signal is applied to each electrode of a plurality of striped thin film light sources, and each of the plurality of striped one-dimensional light modulation arrays orthogonal thereto. A display is performed by applying an image signal to the electrodes and controlling the light transmittance of a desired pixel.
[0049]
A driving method of a two-dimensional matrix flat display element according to a thirty-third aspect is characterized in that gradation is performed by modulating an application time of an image signal.
[0050]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a flat display element according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a partial sectional view of a flat display element according to the first embodiment of the present invention, and FIG. 2 is a plan view of the flat display element according to the first embodiment of the present invention.
In FIG. 1, reference numeral 10 denotes a flat display element, which is a substrate 1, an organic EL (electroluminescence) 2, an optical path selection film 3, a transparent medium (buffer layer) 4, a MEM (mechanical electric light modulation) array 5, and a wavelength conversion function. The color conversion filter 6 having Although the color conversion filter 6 is not shown in FIG. 2, FIG. 1 corresponds to a view taken along the line AA in FIG.
The substrate 1 is used to dispose various films and the like, and is preferably rigid and can be formed of a glass plate, a resin film such as polyethylene terephthalate or polycarbonate. An organic EL (electroluminescence) 2, an optical path selection film 3, a transparent medium (buffer layer) 4, and a MEM (mechanical electro-optical modulation) array 5 are disposed on the substrate 1 in order from the substrate 1 side.
[0051]
The organic EL 2 functions as a thin film light source for the flat display element 10. The flat display element 10 of the present embodiment can realize full-color display by using blue light having a main wavelength of emitted light of 400 nm to 520 nm as the organic EL 2 and combining it with a color conversion filter described later.
The organic EL 2 spreads over the entire surface of the substrate 1 from the substrate 1 side (so-called solid electrode) and the cathode common electrode 22 on the cathode common electrode 22 in a direction perpendicular to the paper surface in FIG. 1 (left and right direction in FIG. 2). A row stripe (band) organic EL layer 24 extending in parallel with each other, and a transparent anode electrode disposed on each stripe (band) organic EL layer 24 to form a row stripe electrode (scanning electrode) 26.
In the above example, the organic EL cathode electrode is solid and the anode electrode is striped, but the reverse is also possible.
The cathode common electrode 22 can be formed of a metal reflective film (AgMg or the like).
The transparent anode electrode 26 is generally composed of a metal or a conductive metal compound made transparent by atomization. As this metal, gold, silver, palladium, zinc, aluminum or the like can be used. As the metal compound, indium oxide, zinc oxide, aluminum-added zinc oxide (common name: AZO) or the like can be used. Specifically, SnO₂(Nesa film), ITO film and the like.
[0052]
Here, an organic EL (Electroluminescence) element constituting the organic EL layer 24 will be described.
The operating principle of the organic EL uses the same current injection as that of a semiconductor light emitting diode, and can easily cover the visible range by selecting an organic material used as a light emitting material. Many high-efficiency materials have been developed and actively researched. The device life has exceeded 10,000 hours in continuous operation and has been put into practical use as a color display.
[0053]
Organic substances used for the light emitting material are classified into (1) a low molecular weight system called a dye molecule and (2) a polymer system called a conductive polymer. Currently, low molecular weight systems that can make organic EL with high purity and high luminous efficiency are often used.
[0054]
In order to form a light emitting element having a multilayer structure, a low molecular light emitting material is often formed mainly by an organic molecular beam deposition (OMBD) method. The advantage of this method is that it is convenient for producing a laminated structure, and a laminated structure having an arbitrary film thickness can be produced.
Some low molecular weight organic dyes are used for dye lasers, and many organic materials that emit light by photoexcitation have been developed.₂Since its development, many materials have been pioneered. These dye molecules can be formed into a film by the OMBD method, and a laminated structure can be easily formed.
[0055]
The dye molecules that emit blue light include anthracene, cyclopentadiene derivatives (PPCP: 1,2,3,4,5-pentaphenyl-1,3-cyclopentadiene), distilbenzene (DSB), its derivatives (PESB )and so on.
[0056]
In addition to blue light emission, Alq₂And tris (4-methyl-8-quinolinolate) alumimume (III) (Almq_Three), Coronene and the like.
Also, (Znq₁) Shows yellow light emission, and red light emission material is berylene derivative (BPPC: N, N'-bis (2,5-di-tert-butylphenyl) -3,4,9,10-perylene-di -carboximide), perylene, DCM: 4- (di-cyanomethylene) -2-methyl-6- (p-dimethyaminostyryl) -4H-pyran, Nile red and the like. In particular, Eu complex (1,10-phenathroline) -tris- (4,4,4-trifluoro-1- (2-thienyl) -butane-1,3-dionate) Europium (III), (Eu (TTA)_Three phen) has a sharp light emission at 614 nm and is used as a light-emitting material with extremely high monochromaticity.
[0057]
The structure of the organic EL layer 24 includes a light emitting layer made of the above light emitting material and a layer made of an electron transporting material and a hole transporting material from above and below across the light emitting layer (electrons and holes in a semiconductor process). And a structure having an n layer and a p layer in which diffusion is formed.
[0058]
The optical path selection film 3 has a function of selectively emitting only incident light components that are totally reflected by shielding incident light components that do not satisfy the total reflection condition among incident light components. An optical element that changes the optical path may be provided on the incident side of the optical path selection film 3. The optical path selection film will be described later.
[0059]
The buffer layer 4 is a transparent medium having a function of totally reflecting the incident light emitted from the optical path selection film 3 and emitting the reflected light to the optical coupling element side by breaking the total reflection condition when the optical coupling element contacts the interface. It is disposed on the entire surface of the cathode electrode 22 and has a function of ensuring flatness by absorbing the vertical difference of the organic EL 2.
The optical elements that change the optical path, the optical path selection film 3, and the buffer layer (transparent medium) 4 are collectively referred to as a total reflection optical member.
[0060]
The MEM array 5 includes a common electrode 52 (solid electrode) extending over the entire surface of the buffer layer 4, an insulating support 54 interposed to form a gap between the common electrode 52 and the movable portion 56, and an insulating support 54. In FIG. 1, the movable part 56 that extends in parallel in the left-right direction (up-down direction in FIG. 2) and the movable part 56 extend in parallel to each other in the left-right direction (up-down direction in the figure) in FIG. 1. It is composed of a column-striped movable portion electrode (image signal electrode) 58 provided. The movable part 56 and the movable part electrode 58 form a flexible thin film. By applying a scanning signal voltage between the cathode common electrode 22 and the desired anode electrode 26 of the organic EL 2 and an image signal voltage between the common electrode 52 and the desired movable part electrode 58 of the MEM array 5. The light can be emitted from the desired MEM array 5 according to the principle described later.
[0061]
The color conversion filter 6 is provided corresponding to the pixel in front of the optical path of the light emitted from the MEM array 5, and converts the light source light from the organic EL 2 emitted from the MEM array 5 into each color of blue, green, and red. It has a wavelength conversion function. The filters 61a, 61b, 61c are formed in a strip shape on the transparent substrate 63 so as to face the image signal electrode Vs. In addition, a black matrix 62 for improving the contrast ratio is disposed between the band-like filters 61a, 61b, and 61c. In this case, the black matrix 62 can be formed of a metal such as a carbon dispersion resin or chromium.
When the main wavelength of the light source light is 400 to 520 nm, the filters 61a, 61b, and 61c have the following functions, respectively.
The filter 61a is a blue color filter and has a function of transmitting blue light with respect to light source light. When the light source light is mainly light of a purple color (wavelength 400 to 410 nm), the filter 61 a further has a function of emitting light in a color including pure blue (wavelength around 450 nm) with respect to purple light. Good. Further, since the filter 61a is transparent to the blue light source light, it may have a light diffusing function. The light diffusion function includes a porous body suitable for mass production shown in FIG. 3A, a dispersion or distribution of substances 20 having different refractive indexes such as high refractive index fine particles shown in FIG. 3B, FIG. c) can be provided by using a light diffuser or light scatterer having irregularities formed on the surface, and according to these light diffusing member or light scatterer, the output light can be directed in any direction by diffusion or scattering. It is possible to disperse, and the output directionality of output light can be eliminated.
As a green color conversion filter, the filter 61b has a function of absorbing light from the light source and emitting a color including green. Further, it is preferable to provide a function of transmitting pure green light (wavelength around 520 nm) with respect to the light source light.
The filter 61c has a function of absorbing light from the light source and emitting a color including red as a red conversion filter. Moreover, it is good to give the light source light the function to transmit pure red light (wavelength around 640 nm).
Each filter can be formed as a filter having the above functions by dissolving or dispersing a pigment or a fluorescent material in the resin.
[0062]
Specific examples of the fluorescent material include the following.
Examples of fluorescent materials that emit blue light by absorbing light from near ultraviolet light to violet include, for example, 1,4-bis (2-methylstyrin) benzene (Bis-MSB), trans-4,4′-diphenylstilbenzene Examples thereof include stilbenzene dyes such as (DPS) and coumarin dyes such as 7-hydroxy-4-methylcoumarin (coumarin 4).
[0063]
As a fluorescent material that emits green light by absorbing light from blue to blue-green, for example, 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidino (9,9s, 1 -Gh) Coumarin (coumarin 153), 3- (2'-benzothiazoyl) -diethylaminocoumarin (coumarin 6), 3- (2'-benzothiazoyl) -7-N, N-diethylaminocoumarin (coumarin 7) Other examples include coumarin dyes such as basic yellow 51, which is a coumarin dye-based dye.
[0064]
Examples of the fluorescent material that absorbs light from blue to green and emits orange to red light include 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostillin) -4H-bilane (DCM). Cyanine dyes, pyridine dyes such as 1-ethyl-2- (4- (p-dimethylaminophenyl) -1,3-butadienyl) -pyridium-percotalate (pyridine 1), xanthines such as rhodamine B and rhodamine 6G And dyes based on oxazine.
[0065]
Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used if they are fluorescent. Alternatively, the fluorescent dye may be previously kneaded into a resin to form a pigment.
[0066]
These fluorescent dyes may be used alone or in combination as necessary. In particular, since the conversion efficiency to red is low by itself, the conversion efficiency can also be increased by using a mixture of the above dyes.
[0067]
Examples of the material for forming the transparent substrate 63 include a glass plate, a resin plate, a resin film, and the like. The resin used for the resin plate and the resin film is preferably a transparent material (visible light transmittance of 50% or more). Examples thereof include transparent resins such as polymethyl methacrylate, polyacrylate, polycarbonate, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxyethyl cellulose, and carboxymethyl cellulose.
[0068]
In addition, an optical filter that absorbs light in the light emission wavelength region of the light source may be provided in front of the optical path of the color conversion filter 6. According to this configuration, since the emission wavelength of the light source is in the visible light range, an ND filter (density filter: Neutral-Density Filter, transmittance 20 to 70%) and a polarizing filter that absorb visible light are displayed (observer). By providing it on the side, the overall density is lowered without deteriorating the color characteristics, so that high contrast can be obtained even in a bright place and high-quality image display can be performed.
[0069]
Next, the planar configuration of the flat display element 10 having the above three-dimensional configuration will be described with reference to FIG. In FIG. 2, a cathode electrode 22 is disposed on the entire surface of the substrate 1, and an organic EL layer 24 constituting one pixel is extended on the cathode electrode 22 in a stripe shape in the horizontal direction in FIG. This is provided in the required number of pixels from top to bottom in FIG.
Further, row stripe electrodes 26 are extended so as to cover these organic EL layers 24. An optical path selection film (not shown), which will be described later, is provided on each row stripe electrode 26, and a solid electrode (common electrode) 52 of the MEM array 5 is provided thereon via a buffer layer 4 (not shown). It is done. A transparent movable part 56 is extended in parallel with each other in the vertical direction with a slight gap therebetween, and a transparent movable part electrode 58 in a row stripe shape covers the movable part 56.
[0070]
A scanning signal voltage Vg is applied between the cathode common electrode 22 (ground side) of the organic EL 2 and each anode electrode 26. That is, as seen on the left side of FIG. 2, the scanning signal voltage is Vg1 for the row electrode of the first row pixel, Vg2 for the row electrode of the second row pixel, and Vg3 for the row electrode of the third row pixel. Given to each line.
[0071]
On the other hand, an image signal voltage Vs is applied between the common electrode 52 (ground side) of the MEM array 5 and each movable part electrode 58. That is, the image signal voltages Vs1, Vs2, and Vs3 are applied to the movable electrode 58 having three stripes from the upper left side of the drawing, respectively.
One pixel of a single color is formed by the overlapping region of the row electrode 26 (Vg1) of the previous first row pixel and the movable portion electrode 58. Therefore, in FIG. 2, three pixels (for example, a region of P <b> 1 in FIG. 2 as one pixel) are configured on the first row pixel electrode 26, and the third row electrode 26 is provided, so that blue, green, That is, a total of nine pixels are formed by arranging three rows of three red pixels.
[0072]
The scanning signal electrode 24 and the image signal electrode 58 are formed by laminating a thin film of the above-described conductive material on the surfaces of the common electrode 22 and the flexible thin film 56 by sputtering or vacuum deposition, and applying a resist on the surface of the thin film. Then, it can be formed by performing exposure and development. Exposure is performed by placing a photomask on the photoresist and irradiating it with ultraviolet rays, and development is performed by processing with a developer that can remove soluble portions of the photoresist.
[0073]
Next, a driving method of the flat display element 10 will be described with reference to FIG.
First, the scanning signal voltage Vg1 is applied between the cathode electrode and the anode electrode of the organic EL for a predetermined time (one horizontal scanning period of about 5 μs), and all the corresponding stripes emit light. In synchronization with this, the image signal voltages Vs1, Vs2, Vs3,..., Vsn may or may not be applied according to the image signal between the common electrode and the movable part electrode of the MEM array. Thus, the MEM movable part of the corresponding stripe is made movable / non-movable, and light is emitted from the movable MEM according to the principle described later, and light is not emitted from the MEM that has not been moved without emitting light.
Next, a scanning signal voltage Vg2 is applied to cause all the corresponding stripes to emit light, and in the same manner as in the case of Vg1, in synchronization with this, an image signal voltage is applied in accordance with the image signal, and the movable portion of the MEM is movable.・ Controls immobility to emit light or shield light.
Similarly, scanning signal voltages Vg3, Vg4,..., Vgm are sequentially applied, and an image signal voltage is applied in accordance with the image signal in synchronization with this to control the movement / non-movability of the MEM movable part, The light is emitted or shielded from light.
Accordingly, the scanning signal voltage Vg is applied to the organic EL in the row order, and the light modulation is performed by the MEM arranged in the column direction, so that the line sequential display is performed.
[0074]
In any of the above operations, pulse width modulation is performed within the range indicated by the shaded portion in FIG. 4 by modulation with MEM, and the density of the emitted light is controlled. When the modulation period is short, it becomes thin and when it is long, it becomes dark. In any of the operations, a pre-application period in which a voltage is applied in advance is provided before the modulation operation by the MEM is performed to stabilize the operation.
[0075]
Since the MEM array modulates light from below by the electromechanical operation of a flexible thin film, there is no need for a polarizing plate that must be used for light modulation by the liquid crystal, and the problem of pixel misalignment and depolarization is considered. Therefore, a full color display can be easily obtained. Further, unlike the case of the plasma display device, the image quality does not depend on the regular arrangement of a large number of electrodes, and a high image quality can be easily obtained. In addition, partition formation for generating plasma for each pixel as in the case of a plasma display device and high vacuum required for a field emission display are not required, so that weight reduction and area increase are facilitated. Manufacturing costs can be reduced.
[0076]
In the present embodiment, the case where visible light, particularly blue light having a main wavelength of 400 to 520 nm is used as the light source has been described. However, in order to realize full color display, UV light (350 to 400 nm) is used as the light source. It may be used. In that case, each filter 61a, 61b, 61c of the color conversion filter 6 absorbs light source light and emits a color including blue (61a), green (61b), and red (61c). Constitute.
[0077]
Here, the principle of light modulation of the MEM array will be described.
There are several principles of light modulation by the MEM array. First, the total reflection mode will be described. FIG. 5 is a cross-sectional view showing the light modulation section of the flat display element according to the second embodiment in the total reflection mode, and FIG. 6 is a cross-sectional view for explaining the operating state of the flat display element shown in FIG. As an operation principle of optically modulating the flexible thin film by electromechanical operation, a light guide diffusion action (hereinafter referred to as light guide diffusion) by separating or contacting the flexible thin film and the transparent signal electrode is used. be able to. In the light guide diffusion, when the gap is formed as a light transmission resistance, when the gap is formed, the emitted light from the signal electrode is blocked or attenuated, while only when the flexible thin film is brought into contact with the signal electrode, Light emitted from the signal electrode is guided (mode coupled) to the flexible thin film, and the light is diffused in the flexible thin film, thereby controlling the intensity of light emitted from the flexible thin film (modulating light).
[0078]
As shown in FIG. 5, one transparent electrode (electrode) 151 is formed on the buffer layer 101. For example, metal oxides such as ITO with a high electron density, very thin metal thin films (aluminum, etc.), thin films in which metal fine particles are dispersed in a transparent insulator, or highly doped wide band gap semiconductors are suitable. is there.
An insulating pillar 105 is formed on the electrode 151. For the pillar 105, for example, silicon oxide, silicon nitride, ceramic, resin, or the like can be used. A movable portion 153 is formed on the upper end surface of the support column 105. A gap (cavity) 111 is formed between the electrode 151 and the movable portion 153. For the movable portion 153, a semiconductor such as polysilicon, insulating silicon oxide, silicon nitride, ceramic, resin, or the like can be used. In addition, the refractive index of the movable portion 153 is preferably equal to or higher than the refractive index of the buffer layer 101.
On the movable portion 153, another transparent electrode 157 is formed with respect to the transparent electrode 151. As an example, a material similar to that of the electrode 151 can be used. The movable portion 153 and the electrode 157 constitute a flexible thin film.
There is a gap 111 between the buffer layer 101 and the movable portion 153, and this gap 111 is substantially determined by the height of the column 105. The air gap 111 is usually formed by etching the sacrificial layer.
[0079]
The operation principle of light modulation of the flat display element 161 configured as described above will be described.
1) When the voltage is OFF:
When the voltages of both the electrodes 151 and 157 are zero and there is a gap 111 (eg, air) between the movable portion 153 and the buffer layer 101, assuming that the refractive index of the buffer layer 101 is nw, at the interface with air The total reflection critical angle θc is
θc = sin^-1(Nw)
It becomes.
Therefore, when the incident angle θ to the interface is θ> θc, the light ray is totally reflected at the interface between the buffer layer 101 and the gap 111 as shown in FIG.
2) When voltage is ON:
When a voltage is applied to both electrodes 151 and 157 to bring the movable part 153 into contact with the surface of the buffer layer 101 or close to a sufficient distance, the light propagates and transmits to the movable part 153 side as shown in FIG. To the side.
According to the flat display element 161 according to this embodiment, light modulation can be performed by position control of the movable portion 153 by voltage application.
Although there is a transparent electrode 151 between the buffer layer 101 and the movable portion 153, the above-described operational problem does not occur as long as it is about the thickness of a normally used thin film (200 nm).
In the flat display element 161, the gap distance and the contact area between the movable portion 153 and the buffer layer 101 can be changed depending on the voltage value. As a result, the amount of transmitted light can be controlled. By utilizing such an action, gradation control is possible by changing the applied voltage.
[0080]
FIG. 7 shows a specific configuration example of the total reflection optical member 200 disposed below the buffer layer 101 in FIGS. 5 and 6. The total reflection optical member 200 has a multilayer structure in which an optical element 201 that changes an optical path from an incident light introduction side, an optical element 202 that selects an optical path, and a transparent medium 205 are stacked in this order. This transparent medium 205 also serves as the buffer layer 101 of FIGS. A transparent medium 207 exists in front of the optical path of the transparent medium 205 of the total reflection optical member 200, and the refractive index n1 (first refractive index) of the transparent medium 205 and the refractive index n2 (second refractive index) of the transparent medium 207. ) Is set so as to satisfy the total reflection condition on the total reflection surface 209 which is an interface between the transparent medium 205 and the transparent medium 207. Specifically, for example, the transparent medium 205 is configured as a glass substrate (n1 = 1.5), and the transparent medium 207 is configured as air (n2 = 1.0). Each layer constituting the total reflection optical member 200 is not substantially absorbed in the wavelength range of the incident light, and suppresses the loss of the incident light and the incident light totally reflected by the total reflection surface 209. This constitutes a highly efficient optical member.
[0081]
The optical element 201 that changes the optical path is an optical element that changes the optical path using refraction, diffraction, light diffusion, light reflection, and the like, and the following types of optical elements can be used as an example. When using refraction, a lens array, a prism array, a refractive index dispersion, or the like is used, and the intensity of incident light is not substantially reduced. When diffraction is used, a transmission type diffraction grating shown in FIG. 8 is used, and a volume hologram (see FIG. 8A), a relief type diffraction grating (see FIG. 8B), or a refractive index modulation type diffraction grating. A phase modulation type diffraction grating, an amplitude modulation type diffraction grating or the like such as (see FIG. 8C) is used, and the angle of the incident light optical path can be set with high accuracy. Each optical element can be mass-produced by, for example, a photopolymer method or an injection molding method.
[0082]
The optical element 203 for selecting the optical path has an angle component in which substantially all of the selectively transmitted light emitted from the optical element 203 has an angle component larger than the total reflection critical angle in the layer in front of the incident light optical path, and other angle components. Incident light is selectively reflected and not transmitted. That is, only incident light having an angle component larger than the total reflection critical angle θc, which is a condition for causing total reflection at the interface between the transparent medium 205 and the transparent medium 207, is transmitted through the optical element 203 that selects the optical path, and other angle components. The incident light is blocked. Note that the total reflection critical angle θc is obtained by the equation (1).
θc = sin^-1(N2 / n1) (1)
[0083]
One configuration example of the optical element 203 for selecting a specific optical path is an optical interference filter made of a dielectric multilayer film. The layer structure of this optical interference filter is shown in FIG.
The optical interference filter is a dielectric multilayer film that is formed by sequentially laminating a high-refractive index material and a low-refractive index material. The optical characteristics of the optical interference filter will be described later in detail. The wavelength which selectively reflects according to an incident angle shifts to the short wavelength side. Now, assuming that the wavelength range of incident light is λiS to λiL (λiS <λiL), for the light having an angle component whose outgoing angle of the selectively transmitted light emitted from the optical element 203 is equal to or less than the total reflection critical angle θc, It selectively reflects substantially all of the incident light in the wavelength range λiS to λiL. According to this configuration, a reflection film capable of selecting an arbitrary wavelength with a large area and a simple configuration can be formed, and the optical element 203 that easily selects an optical path using the incident angle dependence of the reflection wavelength is formed. be able to.
[0084]
Here, a configuration example of the above-described optical interference filter and a result of obtaining the spectral transmittance of the optical element in the configuration example by simulation will be described.
FIG. 10 shows a configuration example of an optical element in which an optical interference filter is interposed. The optical element in this case includes a light diffusing film (refractive index n = 1.5) as an optical element for changing the optical path from the incident light introduction side, a dielectric multilayer film as an optical element for selecting the optical path, and a glass substrate. The layers are stacked in the order of (refractive index n = 1.5). Air (refractive index n = 1.0) is present in front of the optical path of the glass substrate.
The dielectric multilayer film is made of TiO₂/ SiO₂/.../SiO₂/ TiO₂A multilayer film having a 29-layer structure was formed, and the optical thickness of each layer was set to ¼λ (wavelength λ = 440 nm). Also, incident light. A blue light source having a wavelength λ = 400 to 500 nm shown in FIG. 11 was used. In this case, the total reflection critical angle θc is about 40 degrees.
[0085]
When the spectral transmittance and the incident angle dependency of the blue light optical element (dielectric multilayer film) were determined under the above conditions, the results shown in FIGS. 12 and 13 were obtained, respectively. FIG. 12 is a graph showing the change of the spectral transmittance T with respect to the wavelength λ for each incident angle θ, and FIG. 13 is a graph showing the dependence of the spectral transmittance with respect to the incident angle θ on the incident angle for each wavelength λ.
As shown in FIG. 12A, when the incident angle θ is 0 degree, the spectral transmittance T is approximately 0% in the wavelength range (400 to 500 nm) of the blue light source and is transmitted from the optical element. There is no. Further, even when the incident angle θ shown in FIG. 12B is 40 degrees immediately before the total reflection critical angle θc, no light is transmitted from the optical element. When the incident angle shown in FIG. 12C is 70 degrees, the spectral transmittance is about 100% for the P wave and about 0% for the S wave, and the average of the P wave and the S wave is about 40%.
[0086]
In addition, as shown in FIG. 13A, when the wavelength λ = 400 nm on the short wavelength side in the wavelength range of the blue light source, the spectral transmittance is improved from the incident angle θ of about 50 degrees or more for the P wave. In the case of the center wavelength λ = 450 nm shown in FIG. 13B, the spectral transmittance is improved from the incident angle θ of about 42 degrees or more.
[0087]
Further, when a UV light source having a wavelength λ = 350 nm to 400 nm shown in FIG. 14 is used as incident light (total reflection critical angle θ in this case)_CSimilarly, when the spectral transmittance of the optical member (dielectric multilayer film) was obtained under the above conditions at about 40 degrees, the results shown in FIGS. 15 and 16 were obtained. FIG. 15 is a graph showing changes in the spectral transmittance T with respect to the wavelength λ for each incident angle θ, and FIG. 16 is a graph showing the spectral transmittance T with respect to the incident angle θ for each wavelength λ.
[0088]
As shown in FIG. 15A, when the incident angle θ is 0 degree, the spectral transmittance T in the wavelength range of the UV light source is substantially 0% and is not transmitted from the optical member. Further, the incident angle θ shown in FIG. 15B is the total reflection critical angle θ._CIn the case of 40 degrees, which is immediately before, the light is not transmitted from the optical member. When the incident angle θ shown in FIG. 15C is 70 degrees, the spectral transmittance is approximately 100% for the P wave and is approximately 0% for the S wave, and the average of the P wave and the S wave. Is about 50%.
[0089]
Further, as shown in FIG. 16A, when the wavelength λ = 350 nm on the short wavelength side in the wavelength range of the UV light source, the spectral transmittance is improved from the incident angle θ of about 50 degrees or more for the P wave. In the case of the center wavelength λ = 375 nm shown in FIG. 16B, the spectral transmittance is improved when the incident angle θ is about 46 degrees or more, and the wavelength on the long wavelength side shown in FIG. In the case of λ = 400 nm, the spectral transmittance is improved from the incident angle θ of about 42 degrees or more.
[0090]
Therefore, the incident light in the wavelength range of the blue light source can be obtained by totally reflecting the optical element using the P wave or changing the various conditions of the optical element to appropriately design the spectral characteristic of the S wave to a characteristic close to the P wave. Can be selectively reflected when the incident angle θ is equal to or smaller than the total reflection critical angle θc, and can be transmitted when the incident angle θ is larger than the total reflection critical angle θc. Thereby, the dielectric multilayer film of the optical element can be made to function sufficiently practically as an optical element for selecting an optical path.
[0091]
In the above, as an example of the dielectric multilayer film, TiO₂/ SiO₂Although the multilayer film which consists of this was mentioned, it is preferable to select the material suitably with respect to the wavelength of the target light. For example,
For visible light and infrared light,
・ As a high refractive index material (a material having a refractive index of about 1.8 or more),
TiO₂, CeO₂, Ta₂O_Five, ZrO₂, Sb₂O_Three, HfO₂, La₂O_Three, NdO_Three, Y₂O_Three, ZnO, Nb₂O_Five
・ As a relatively high refractive index material (a material having a refractive index of approximately 1.6 to 1.8),
MgO, Al₂O_Three, CeF_Three, LaF_Three, NdF_Three
・ As a low refractive index material (a material having a refractive index of about 1.5 or less),
SiO₂, AiF_Three, MgF_Three, Na_ThreeAlF₆, NaF, LiF, CaF₂, BaF₂
Etc. are preferred.
[0092]
For ultraviolet rays
・ As a high refractive index material (a material having a refractive index of about 1.8 or more),
ZrO₂, HfO₂, La₂O_Three, NdO_Three, Y₂O_Three
Or
TiO₂, Ta₂O_Five, ZrO₂
(However, the wavelength of light is approximately 360 nm to 400 nm)
・ As a relatively high refractive index material (a material having a refractive index of approximately 1.6 to 1.8),
MgO, Al₂O_Three, LaF_Three, NdF_Three
・ As a low refractive index material (a material having a refractive index of about 1.5 or less),
SiO₂, AlF_Three, MgF₂, Na_ThreeAlF₆, NaF, LiF, CaF₂
Etc. are preferred.
[0093]
The optical interference filter may be a metal / dielectric multilayer film obtained by adding a metal film to the layer structure of the dielectric multilayer film. An optical interference filter made of a dielectric multilayer film or the like can be formed by depositing a plurality of thin film materials on a transparent support substrate by EB vapor deposition (electron beam co-evaporation), sputtering, or the like. The thin film material may be an organic multilayer film having a different refractive index or an organic multilayer film containing an inorganic substance, and in this case, it can be formed at a lower cost by coating, laminating, or the like.
[0094]
Next, the optical properties of the optical element 201 that changes the optical path and the optical element 203 that selects the optical path will be described in detail.
First, consider a case where the optical element 201 that changes the optical path changes the optical path by refraction, for example. As shown in FIG. 17, an optical element (average refractive index nt) that changes the optical path, an optical element that selects the optical path (average refractive index ns), a transparent medium u (average refractive index nu), and a transparent medium v (average refractive index). nv) In the case of an optical element in which the transparent medium w (average refractive index nw) on the front side of the total reflection surface is arranged in this order, if the interface between the transparent medium v and the transparent medium w is a total reflection surface, The relationship between the incident angle at the interface and the average refractive index of each medium can be expressed as shown in equation (2).
[0095]
nv · sin θv = nw
nu · sin θu = nv · sin θv = nw
ns · sin θs = nu · sin θu = nw
nt · sin θt = ns · sin θs = nw (2)
Here, θt, θs, θu, and θv are optical path angles in the respective media.
[0096]
Therefore, as a condition of the optical element 201 that changes the optical path,
sinθt> nw / nt
It is necessary to output at least the light of the angle θt that satisfies the above condition and output it in front of the optical path. Preferably, as much light as possible with an angle θt that satisfies this condition is included and output to the front of the optical path. If the transparent medium w is air, nw = 1, and the above condition is
sinθt> 1 / nt
It becomes.
[0097]
Next, the characteristics of the optical element 203 for selecting the optical path will be described in detail with reference to FIGS.
FIG. 18 shows the incident angle of the incident light to the optical element 203, FIG. 19 is a graph showing the spectral transmittance of the optical element 203 with respect to the wavelength of the incident light for each incident angle, and FIG. It is a figure which shows these optical paths.
[0098]
First, as shown in FIG. 18, an incident angle θ for writing incident light to the optical element 203.₀, Θ₁, Θ₂, Θ_ThreeConsidering the case where the light is incident on the optical element 203, the spectral transmittance of the optical element 203 changes as shown in FIG. That is, the incident angle is θ less than or equal to the total reflection critical angle θc.₀In the case of (0 degree), the spectral transmittance is substantially 0% with respect to the wavelength range λiS to λiL of the incident light, and a light shielding state (a state of being reflected without being transmitted) is obtained. On the other hand, when the incident angle is larger than the total reflection critical angle θc, the incident angle is θ₁, Θ₂, Θ_ThreeAs the value increases, the transmission characteristic of the spectral transmittance shifts to the short wavelength side, so that the amount of transmitted light increases (see also FIGS. 12, 15B, and 15C). That is, as the incident angle of the incident light to the optical element 203 that selects the optical path becomes a shallow angle with respect to the surface of the optical element 203, the wavelength of the selectively reflected incident light shifts to the short wavelength side. As a result, the incident angle component of the incident light is θ₀Is not transmitted, and the incident angle component is larger than a specific angle θ₁, Θ₂, Θ_ThreeOf light in this order will be transmitted in this order. Therefore, by designing the optical element 203 so that only the incident light component whose spectral characteristic is larger than the total reflection critical angle θc at the predetermined interface is transmitted, the incident light component that does not satisfy the total reflection condition is shielded. Only the incident light component that is totally reflected can be selectively emitted from the optical element 203.
[0099]
As described above, the incident light path when the total reflection optical member 200 is configured using the optical element 203 designed to transmit only the incident light component larger than the total reflection critical angle θc on the total reflection surface 209 is illustrated in FIG. 20 will be described.
FIG. 20A shows an optical path A in which the light incident on the optical element 203 that selects the optical path is reflected by the optical element 203, and the light incident on the optical element 203 that selects the optical path passes through the optical element 203. An optical path B that is totally reflected by the total reflection surface 209 that is an interface between the transparent medium 205 and the transparent medium 207 in front of the optical path is shown.
[0100]
The optical path A is a case where the incident angle θi of the incident light is equal to or smaller than the total reflection critical angle θc of the total reflection surface 209, and the optical element 203 is selectively transmitted on the surface without transmitting the light having such an incident angle component. Reflect. For this reason, light having an incident angle component equal to or smaller than the total reflection critical angle θc is blocked by the optical element 203 with respect to the front of the optical path.
The optical path B is a case where the incident angle θi of the incident light is larger than the total reflection critical angle θc in the total reflection surface 209, and the optical element 203 transmits light having such an incident angle component. Therefore, light having an incident angle component larger than the total reflection critical angle θc is transmitted through the optical element 203 and introduced into the transparent medium 205, and is totally reflected by the total reflection surface 209.
In FIG. 20A, the refractive index na on the incident light side and the refractive index nb of the transparent medium 205 are equal, and the incident angle θi with respect to the optical element 203 and the incident angle θs at the total reflection surface 209 are equal. Shows the case.
[0101]
On the other hand, in FIG. 20B, the refractive index na on the incident light side and the refractive index nb of the transparent medium 205 are different, and the incident angle θi with respect to the optical element 203 and the incident angle θs on the total reflection surface 209 are different. Shows the case. The optical element 203 in this case is designed so that the incident angle θs at the total reflection surface 209 is larger than the total reflection critical angle θc.
[0102]
By constructing the total reflection optical member 200 using the optical element 203 that selects the optical path designed as described above, the optical path is introduced from inside or outside the total reflection optical member 200 as indicated by an arrow in FIG. When planar incident light made of collimated light or diffused light enters the optical element 201 that changes the optical path, the optical path changes due to diffusion or the like from the light irradiation position. When the light having the changed optical path reaches the optical element 203 that selects the optical path, only incident light having an angle component larger than the total reflection critical angle θc on the total reflection surface 22 serving as an interface between the transparent medium 205 and the transparent medium 207 is obtained. Light incident through the optical element 203 and having other angle components is selectively reflected on the surface of the optical element 203 toward the light incident side.
[0103]
Therefore, only the light that is totally reflected by the total reflection surface 209 out of the light incident on the total reflection optical member 200 is introduced in front of the optical path, and the introduced light is totally reflected by the total reflection surface 209. That is, in the optical element 203 that selects the optical path, substantially all of the transmitted light emitted from the optical element 203 is larger than the total reflection critical angle in the total reflection surface ahead of the incident light optical path from the optical element 203 that selects the optical path. Incident light having an angle component is selectively reflected and is not transmitted. Note that light guide, accumulation, confinement, and the like are not substantially performed in a medium having a total reflection surface.
[0104]
Further, part of the light reflected on the incident light introduction side on the surface of the optical element 203 for selecting the optical path is reflected on the interface (reflective layer) on the light incident side of the optical element 201 that changes the optical path, and again the optical path. Is inserted into the optical element 203 for selecting. The re-entered light has an incident angle that is greater than the total reflection angle θc, passes through the optical element 203 and is introduced into the transparent medium 14.
[0105]
The MEM array will be further described.
The MEM array operates the flexible thin film electromechanically, for example, breaks the condition of total reflection of incident light on the total reflection surface, couples the light to the flexible thin film, and outputs it to the front of the optical path. is there. The MEM array is appropriately provided with optical path changing means for changing the optical path of the extracted light and specific wavelength component absorbing means for absorbing the specific wavelength component. Specifically, for example, the following types (1) to (4) can be used.
(1) Change the optical path by refraction or have the function
The optical path of the output light taken out by placing it close to the total reflection surface is changed by refraction. For example, the lens array shown in FIG. 21A, the prism array shown in FIG. Examples thereof include a gradient index lens body shown in 21 (c). According to these lens arrays and prism arrays, the output light extracted from the total reflection surface of the total reflection optical member can be condensed or diffused to be emitted in different directions, and the output light can have a directivity. Further, it is possible to eliminate the output directivity with a simple configuration without reducing the intensity of the output light.
[0106]
(2) Transmission type diffraction grating or one having the function
As the transmission type diffraction grating that transmits the extracted light and changes the emission direction by diffraction, the same volume hologram as shown in FIG. 7A, the relief type diffraction grating shown in FIG. 7B, and FIG. Examples thereof include a refractive index modulation type diffraction grating shown in c) and an amplitude modulation type diffraction grating. According to these transmission type diffraction gratings, the emission angle of output light can be set accurately. Further, for example, mass production is possible by a photopolymer method or an injection molding method, and the cost of the optical element itself can be reduced.
[0107]
(3) Light diffuser or light scatterer or one having the function
Examples of the light diffuser or light scatterer that diffuses or scatters the extracted light include a porous material suitable for mass production shown in FIG. 3A, the high refractive index fine particles shown in FIG. Examples thereof include dispersions or distributions of substances 20 having different refractive indexes, light diffusers or light scatterers having irregularities formed on the surface shown in FIG. According to these light diffusers or light scatterers, the output light can be scattered in an arbitrary direction by the diffuser or the scattering, and the emission directionality of the output light can be eliminated.
[0108]
(4) Exciting light emission or having its function
Examples of those that emit light upon receiving incident light include phosphors and photoluminescence. According to this, the output light extracted from the total reflection surface of the total reflection optical member can be excited to emit light and can be developed into a specific color. In addition, by setting the specific color to, for example, blue, green, or red, it is possible to combine these light emitters according to the display image and display a full color image.
[0109]
In accordance with the principle described above, the MEM array introduces the incident light from the light source directly into the total reflection optical member with high efficiency without using a light guide plate or an optical waveguide, thereby improving the coupling efficiency with the incident light, Highly efficient light can be obtained without being affected by the thinning of the flat display element itself. Thereby, the incident light extracted from the total reflection optical member from the region where the MEM array is provided is emitted with high efficiency in front of the optical path. Therefore, only the area provided in the selected MEM array shines on the surface on the front side of the optical path of the flat display element, and light is emitted from the flat display element like an image. That is, it is possible to display an image only at a necessary portion. Further, according to this configuration, a local light amount reduction due to crosstalk that occurs when using a light guide plate or an optical waveguide is prevented, and display can be performed with uniform brightness over the entire display image.
[0110]
In addition, since a part of incident light reflected at each interface in the flat display element is re-entered in front of the optical path due to reflection at the interface, high output of the flat display element can be easily achieved. Further, since the total reflection optical member alone does not substantially generate transmitted light, the light utilization efficiency can be improved. In addition, by making the gas contact interface where the total reflection optical member comes into contact with air (which may be an inert gas) as a total reflection surface, a simple structure can be obtained without separately providing a refractive index layer that causes total reflection. it can.
Further, since no light is emitted from the area where the MEM array is not placed, the difference between the brightness of the display image and the surrounding brightness is increased, and the visual effect such as visually enhancing the display image is provided. Is also accompanied. Further, by dynamically controlling the image display, it is possible to configure an advertising billboard and an electric signboard that attract attention.
The flat display element described above is not limited to being used for image display, but can be used as a medium for displaying various information such as character information and graphic information.
[0111]
Next, a description will be given of a light-shielding / emitting configuration of the MEM array based on another principle.
FIG. 22 is a perspective view showing a light modulation unit based on another principle, and FIG. 23 is a cross-sectional view for explaining an operation state of the light modulation unit shown in FIG.
On the buffer layer 301, a transparent electrode 303 transparent to a desired light beam is provided. The buffer layer 301 is shielded by an insulating light-shielding film 305 except for the opening through which light is transmitted. An insulating film 307 is formed on the surfaces of the transparent electrode 303 and the light shielding film 305.
Insulating columns 309 are provided on both sides of the opening on the buffer layer 301. A light shielding plate 311 that is a flexible thin film is provided at the upper end of the support column 309. The light shielding plate 311 has a cantilever structure and is made of a conductive material that absorbs or reflects light source light. The conductive light shielding plate 311 having the beam structure may be composed of a single thin film, or may be composed of a plurality of thin films.
Specifically, a metal thin film such as aluminum or chrome, a single element structure made of a semiconductor such as polysilicon, an insulating film such as silicon oxide or silicon nitride, a structure obtained by depositing metal on a semiconductor thin film such as polysilicon, or a dielectric It can be set as the composite structure which vapor-deposited filters, such as a body multilayer film. The light shielding plate 311 corresponds to the shape of the opening, and is slightly larger than the size of the opening.
[0112]
The flat display element 315 having the light modulation unit 313 configured as described above is arranged on a flat light source unit (not shown). When no voltage is applied between the conductive light shielding plate 311 and the transparent electrode 303, the light shielding plate 311 faces the opening, and the light source light transmitted through the opening is absorbed or reflected by the light shielding plate 311. (FIG. 23 (a)).
On the other hand, when a voltage is applied between the light shielding plate 311 and the transparent electrode 303, the light shielding plate 311 is tilted toward the transparent electrode 303 side while twisting due to electrostatic stress acting between them (FIG. 23B). That is, the shielding by the light shielding plate 311 is eliminated. Thereby, the light source light transmitted from the opening can be transmitted further forward. When the voltage is set to zero again, the light shielding plate 311 returns to the original position due to the elasticity of the beam.
Further, the degree of inclination of the light shielding plate 311, that is, the amount of transmitted light can be continuously changed according to the voltage value. By utilizing this, gradation control by applied voltage is possible.
As described above, according to the above-described flat display element 315, the light path can be changed and the light modulation can be performed by bending the light shielding plate 311.
If this principle is used, the optical path selection film used in the total reflection mode becomes unnecessary, which contributes to simplification of the manufacturing process, simplification of the apparatus, and cost reduction.
Note that the MEM array of the flat display element may be stabilized by degassing and then enclosing a rare gas and sealing the whole to prevent the influence of disturbance.
[0113]
【The invention's effect】
As described above in detail, according to the display device according to the present invention, since the light modulation unit that modulates the light of the planar light source by electromechanical operation is disposed on the organic EL light source, each material is for visible light. In particular, a color filter (CF) material can be used for the optical path selection film (Ch-LC).
In addition, since the organic EL drive can be completely static, and the MEM can also be fully static, the hysteresis characteristics and memory characteristics of the MEM element are not required, and PWM modulation is used, so there is flexibility in providing gradation. Response speed can be reduced. And it is line-sequential light emission display, and moving image display property improves.
In the conventional organic EL simple matrix type, a large screen is impossible due to reverse bias, wiring voltage drop, etc. However, since the organic EL according to the present invention does not use TFT (low temperature p-Si), a large screen display Can be built.
Furthermore, since a liquid crystal switch is not used, problems such as a polarizing plate and a polarization axis do not occur.
In addition, since organic EL (visible light) can be used in the present invention, various kinds of organic materials that could not be used with UV light can be used, and the range of selection of materials is widened.
[Brief description of the drawings]
1 is a partial cross-sectional view of a flat display element according to a first embodiment of the present invention, and is a view taken along the line AA of FIG.
FIG. 2 is a plan view of the flat display element according to the first embodiment of the present invention.
FIGS. 3A and 3B are diagrams showing a light diffusing function, wherein FIG. 3A is a porous body, FIG. 3B is a dissimilar refractive index distribution body / dispersion body in which substances having different refractive indexes are distributed and dispersed; c) is a light scatterer or light diffuser having irregularities formed on the surface.
FIG. 4 is a diagram illustrating a method for driving a flat display element.
FIG. 5 is a cross-sectional view showing a light modulation section of a flat display element, and a view showing a non-driving state.
6 is a diagram illustrating a driving state of a light modulation unit of the flat display element illustrated in FIG. 6;
FIG. 7 is a diagram illustrating a specific configuration example of a total reflection optical member.
8A and 8B are diagrams showing a transmission type diffraction grating, where FIG. 8A is a volume hologram, FIG. 8B is a relief type diffraction grating, and FIG. 8C is a refractive index modulation type diffraction grating.
FIG. 9 is a diagram illustrating a layer configuration of an optical interference filter.
FIG. 10 is a diagram illustrating a configuration example of a total reflection optical member provided with an optical interference filter.
FIG. 11 is a diagram showing a wavelength band of incident light of blue light.
FIG. 12 is a graph showing a change in spectral transmittance with respect to a wavelength of blue light for each incident angle.
FIG. 13 is a graph showing the incident angle dependence of the spectral transmittance of blue light for each wavelength.
FIG. 14 is a diagram illustrating a wavelength band of incident light of UV light.
FIG. 15 is a graph showing the change in spectral transmittance with respect to the wavelength of UV light for each incident angle.
FIG. 16 is a graph showing the incident angle dependence of the spectral transmittance of UV light for each wavelength.
FIG. 17 shows an optical element that changes an optical path, an optical element that selects an optical path, a transparent medium u, a transparent medium v, and a transparent medium w on the front side of the total reflection surface in this order. It is a figure which shows the relationship between the incident angle in an interface, and the average refractive index of each medium.
FIG. 18 is a diagram illustrating an incident angle of incident light on an optical element for selecting light.
FIG. 19 is a graph showing the spectral transmittance of an optical element for selecting an optical path for each incident angle with respect to the wavelength of incident light.
FIG. 20 is a diagram showing optical paths inside and outside an optical element for selecting an optical path.
FIG. 21 is a diagram showing an optical element that changes an optical path by refraction, wherein (a) is a porous body, (b) is a prism array, and (c) is a gradient index lens body.
FIG. 22 is a perspective view showing another form of the light modulation section in the flat display element.
23 is a cross-sectional view of the light modulation section shown in FIG.
[Explanation of symbols]
1 Substrate
2 Organic EL
3 Optical path selection film
4 Buffer layer
5 MEM (Mechanical Electrical Light Modulation) Array
6 color conversion filter
10 Flat display element
20 Substances with different refractive indices
22 Cathode common electrode
24 Organic EL layer
26 Anode electrode (scanning signal electrode)
52 Common electrode
54 Insulation support
56 Moving parts
58 Movable part electrode (electrode for image signal)
62a Blue color filter
62b Green conversion filter
62c Red color conversion filter
64 Transparent substrate
66 Black Matrix
101 Buffer layer
105 Insulating support
111 gap
151 electrode
153 Movable part
157 electrode
161 Flat display element
200 Total reflection optical member
201 Optical elements for changing the optical path
203 Optical element for selecting optical path
205 Transparent medium
207 Transparent medium
209 Total reflection surface
301 Buffer layer
303 Transparent electrode
305 Light-shielding film
307 Insulating film
309 Insulating post
311 Shading plate
313 Light modulator
315 Flat display element

Claims (33)

A plurality of striped thin-film light sources that emit monochromatic light on a substrate are disposed thereon, and a plurality of striped one-dimensional light modulation arrays that electromechanically control light transmittance from the thin-film light sources are provided on the substrate. A two-dimensional matrix element arranged so as to be orthogonal to the striped thin film light source. A plurality of striped thin-film light sources that emit monochromatic light on a substrate are disposed thereon, and a plurality of striped one-dimensional light modulation arrays that electromechanically control light transmittance from the thin-film light sources are provided on the substrate. A two-dimensional matrix flat display element which is disposed so as to be orthogonal to the striped thin-film light source and provided with a filter corresponding to a pixel at least in front of an optical path including the one-dimensional light modulation array. The two-dimensional matrix flat display element according to claim 2, wherein the thin film light source is an organic EL. 4. The two-dimensional matrix flat display element according to claim 2, wherein the filter having the wavelength conversion function is disposed apart from the one-dimensional light modulation array. 5. 4. The two-dimensional matrix flat display element according to claim 2, wherein the filter having the wavelength conversion function is provided in contact with or in the one-dimensional light modulation array. 5. 6. The two-dimensional matrix flat display element according to claim 2, wherein a main wavelength of light from the thin film light source is 350 nm to 400 nm. 7. The two-dimensional matrix plane display according to claim 6, wherein the filter having a wavelength conversion function includes a fluorescent material that emits light in a color including red and / or green and / or blue with respect to light source light. element. Between the filter having the wavelength conversion function and the one-dimensional light modulation array, light having a color including red and / or green and / or blue that transmits at least part of light source light and emits light from the fluorescent material. The two-dimensional matrix flat display element according to claim 7, further comprising a second filter for reflection. 6. The two-dimensional matrix flat display element according to claim 2, wherein a main wavelength of light from the thin film light source is 400 nm to 520 nm. 10. The two-dimensional matrix flat display element according to claim 9, wherein the filter having a wavelength conversion function includes a fluorescent material that emits light in a color including red and / or green with respect to light source light. The two-dimensional matrix flat display element according to claim 9, wherein the filter having a wavelength conversion function has a function of transmitting red and / or green light. The filter according to claim 9, wherein a filter having a function of transmitting blue light with respect to light source light is provided in front of an optical path including the one-dimensional light modulation array so as to correspond to a pixel. Two-dimensional matrix flat display element. The two-dimensional matrix plane display according to any one of claims 9 to 12, wherein the filter having a function of transmitting blue light includes a fluorescent material that emits light in a color including blue with respect to light source light. element. The two-dimensional matrix flat display element according to any one of claims 9 to 13, which has a function of transmitting the blue light but has a light diffusion function. The two-dimensional matrix flat display element according to claim 2, further comprising an ND film or a polarizing film that attenuates external light in front of the filter having the wavelength conversion function. The two-dimensional matrix flat display element according to any one of claims 2 to 15, wherein the one-dimensional light modulation array uses a principle that a flexible thin film is displaced by static electricity. 17. The two-dimensional matrix flat display element according to claim 16, wherein the one-dimensional light modulation array controls light transmittance by changing an optical path opening area by displacement of the flexible thin film. The one-dimensional light modulation array is configured to control a light transmittance by moving a coupling element by displacement of the flexible thin film to transmit near light and blocking light by total reflection. Two-dimensional matrix flat display element. The two-dimensional matrix flat display element according to claim 16, wherein the one-dimensional light modulation array is of a backlight incident type, and an optical path selection film is disposed on the thin film light source. The thin-film light source and the thin-film light source that is arranged facing the thin-film light source and introduced from the thin-film light source are totally reflected, and the incident light is emitted substantially in front of the optical path. A total reflection optical member provided on the other surface in front of the optical path and a total reflection optical member that is not allowed to pass, and is provided close to the display image at a desired position on the total reflection surface of the total reflection optical member so that incident light on the total reflection surface 19. The two-dimensional matrix flat display element according to claim 18, further comprising a one-dimensional light modulation array that breaks down the total reflection condition and extracts incident light from the total reflection surface by combining it. 21. The two-dimensional matrix flat display element according to claim 20, wherein the total reflection optical member includes an optical element that changes an optical path of incident light on the surface. 21. The two-dimensional matrix flat display element according to claim 20, wherein the total reflection optical member includes an optical element that selects an optical path of incident light on the surface. The total reflection optical member includes an optical element that changes an optical path of the incident light and an optical element that selects the optical path of the incident light in this order from the incident light introduction side on the surface. Item 20. The two-dimensional matrix flat display element according to Item 20. The two-dimensional matrix flat display element according to any one of claims 20 to 23, wherein the one-dimensional light modulation array has optical path changing means for changing an optical path of the extracted light. The two-dimensional matrix flat display element according to claim 24, wherein the optical path changing unit changes the optical path of the extracted light by refraction. 26. The two-dimensional matrix flat display element according to claim 25, wherein the optical path changing means includes any one of a lens array, a prism array, and a gradient index lens body. The two-dimensional matrix flat display element according to claim 24, wherein the optical path changing unit changes an optical path of the extracted light by diffraction. 28. The two-dimensional matrix flat display element according to claim 27, wherein the optical path changing means is one of a volume hologram, a phase modulation type diffraction grating, and an amplitude modulation type diffraction grating. The two-dimensional matrix flat display element according to claim 24, wherein the optical path changing unit changes the optical path of the extracted light by light diffusion or light scattering. 30. The two-dimensional according to claim 29, wherein the optical path changing means is any one of a porous body, a different refractive index dispersion or distribution body, or a light diffuser or light scatterer having irregularities on the surface. Matrix flat display element. 31. The two-dimensional matrix flat display element according to claim 2, wherein a scanning signal is applied to the thin film light source, and an image signal is applied to the one-dimensional light modulation array. A scanning signal is applied to each electrode of a plurality of striped thin-film light sources, an image signal is applied to each electrode of a plurality of striped one-dimensional light modulation arrays orthogonal to the electrodes, and the light transmittance of a desired pixel is obtained. A driving method of a two-dimensional matrix flat display element for performing display under control. The method of driving a two-dimensional matrix flat display element according to claim 32, wherein gradation is performed by modulating the application time of the image signal.

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