JPH0695162A - Optical modulation element - Google Patents

Abstract

PURPOSE:To form the patterns of the optical wave front modulation element to be electrically controlled in real time with high reliability by using liquid crystal diffraction elements by reducing the thickness of liquid crystals and controlling fine electric field distribution for forming fine diffraction patterns. CONSTITUTION:Titanium oxide, tin oxide, indium oxide or the mixture composed thereof is used for transparent electrodes 14, 16 formed on the surfaces of transparent substrates 12, 18 consisting of glass, sapphire, rock crystals, plastics, etc. W<=H and W<=S are attained when the thickness of the liquid crystal layers is designate as 11, the width of the electrodes as 13, an inter- electrode spacing as 15, an inter-substrate spacing as H, an electrode width as W and the spacing distance from a grounding electrode as S. The extremely fine setting of the position accuracy of the patterns formed by the liquid crystal elements is, therefore, possible, if the W is made finer, i.e., at W<<H. The control of the liquid crystal layers of the inter-electrode spacing regions by utilizing the bleeding of the electric lines of force from the electrodes with respect to the inter-electrode spacings is possible by setting at W<=S. Further, the smooth connection of the electric fields of the inter-electrode spacings to the electric fields right under the adjacent electrodes is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spatial light modulator for modulating a light wavefront, and more particularly to a structure and driving of a spatial light modulator of a fine electrode liquid crystal device type.

[0002]

2. Description of the Related Art Conventionally, a photographic diffraction plate, a diffraction grating by machining, or an optical lens has been widely used for temporally fixed control of a light wave front, and an acousto-optical element for temporally controlled control. Transparent piezoelectric elements such as and PLZT have been used. A precise fixed optical wavefront modulation element created by taking sufficient time can be used for time-fixed control of the optical wavefront, but for moving pictures, the pattern update time of the optical wavefront modulation element is tens of msec or less. And need to be fast. Although it is possible to mechanically switch many holograms that were taken in advance like a movie and show them as a movie, the elements and technology suitable for real-time screen updating that captures and reproduces the actual movie are It was thought to not exist. On the contrary,
Various studies have been done on moving diffraction gratings, but none have been satisfactory. For example, a phase modulator for a light wave front that forms a pattern on an oil film by an electron beam and controls the film thickness is bulky such as a vacuum tube or an exhaust system, and the life of the oil film is short, making it difficult to use. In a system that scans a smectic liquid crystal with a laser beam, resolution up to several μm is possible, but since it is thermal writing, it takes time for heat conduction and thermal equilibrium, and it takes about 1 second to draw one screen. , Speed is insufficient.

Since the liquid crystal video display device developed for the display of liquid crystal televisions and personal computers is compatible with moving images, the response speed is as small as 20 mSec to 50 mSec. The liquid crystal element for display is a powerful element in terms of response speed and pixel density, and its possibility as a diffraction element has been studied in the past. However, in the estimation of the practical size limit of the liquid crystal pixel, the lower limit is considered to be several tens of μm, and the liquid crystal layer has a thickness of 5 μm for STN (super twist: a liquid crystal element having a twist angle of 120 to 270 degrees, for example). ), The pixel electrode width and the minimum dimension of the pixel electrode gap are each 5 μm, that is, the pixel pitch 10
The limit is about μm, and even the ferroelectric liquid crystal element is about 4 μm, and the resolution is 100 to 250 (lines / mm), and it is considered impossible to request a higher resolution than the limit of the thickness of the liquid crystal layer. It was being done.

In the present invention, the shape of the diffractive pattern to be formed is controlled by precisely controlling the liquid crystal molecule group as a function of location by a fine synthetic electric field formed by combining pixels finer than the liquid crystal layer thickness and pixel gaps. We will present a method to accurately achieve precision and position accuracy. In addition, examples of liquid crystal cell structure / orientation / materials necessary for achieving this element structure, and application examples utilizing the characteristics of the diffraction element of the present invention will be shown.

The structures of the conventional optical wavefront modulation element and the conventional liquid crystal display element will be described below with reference to the drawings. Conventionally, the pixel size of a liquid crystal display device used in a personal computer or a word processor is one pixel per human eye.
The pixel size was determined on the assumption that it can be identified as a point. Therefore, the pixel size of the liquid crystal element is 250 μm or less as a distinguishable pixel size at a human visual distance of about 25 cm.
350 μm, and the gap between the pixels is approximately 10% of the pixel size in order to secure an aperture ratio of 80% or more and to increase the manufacturing yield.
That is, it was set to 25 to 35 μm. When reproducing a video image, it is not necessary to identify the pixel itself, and it is easier to see if the pixel is not conspicuous. Therefore, the pixel size is 100 μm.
A device of ˜200 μm was used. Since a liquid crystal viewfinder used for a photographing monitor of a video camera and a liquid crystal element of a projection type display device are optically enlarged, a prototype having a pixel size of 30 μm and a pixel gap of 5 to 8 μm has been produced. These have a resolution of several tens of lines / 1 mm, which is insufficient for use in a diffraction element. Moreover, when the pixel size is reduced, the aperture ratio of the pixel is reduced by the square of the size ratio. According to the conventional design concept, when the liquid crystal layer thickness is 5 μm, the pixel electrode width / dimension is 18 μm in order to secure the aperture ratio of 50% or more.
・ When the electrode gap is 6 μm, the resolution is about 40 lines / mm, which is a level usable for holography, that is, several hundred lines / mm.
It is far below mm to several thousand lines / mm. Further, when the electrode pitch is reduced, the aperture ratio of pixels is rapidly reduced, and it is considered that a resolution of several tens of lines / mm or more is not realistic, and further higher resolution has been abandoned.

[0006]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to realize the pattern formation of an optical wavefront modulation element which is electronically controlled in real time with high accuracy by using a liquid crystal diffraction element. More specifically, a) Formation of a precise modulation pattern in which the spatial frequency noise component of the diffraction pattern is suppressed, and formation of a modulation pattern in a minute dimension region equal to or less than the liquid crystal thickness. b) Realization of precise pattern position accuracy by suppressing the position error of the diffraction pattern. c) Avoiding a decrease in aperture ratio when forming a fine diffraction pattern. Is.

[0007]

In order to solve the above problems, in the present invention, not only the liquid crystal layer is made thin, but also a fine electric field distribution is controlled to form a fine diffraction pattern. The electrode structure and driving method for this purpose will be clarified. According to the conventional concept of driving a liquid crystal, the liquid crystal layer immediately below the transparent electrode for driving the liquid crystal is electrically driven. Therefore, it is recognized that the size of the pixel electrode is equal to the pixel size, and the lateral gap between the electrodes is treated as a dead region that is not electrically controlled or a frame region that reduces the aperture ratio of the pixel. From this point of view, the reduction of the electrode size leads to the reduction of the aperture ratio, which gives the lower limit of the pixel pitch. That is, the concept of forming the pixel electrode started from the fact that the pixel had a recognizable size as a "screen display device". From this point, if the size of the pixel is 10% or less, it is said that there is an advantage that the larger the electrode gap is, the easier the processing becomes. Furthermore, the pixel is designed under the condition that the isolated pixel can be controlled independently. The existence of a gap between pixels was considered as an unconscious precondition as "abandonment of control" = "OFF (electric field = 0) area" = "unavoidable waste area". Further, the electrode gap distance in the case of forming the pixel electrode = processing limit size = several μm.
The "electrode gap size" is about 20 .mu.m for a large-sized personal computer liquid crystal display device and about 5 to 15 .mu.m for a small TV liquid crystal device. As a result, when the liquid crystal element is designed as a spatial modulation element other than the display device, the lower limit of the pitch is the pixel gap of the liquid crystal layer thickness + the electrode dimension of the same degree, that is, the pitch of 10 μm or more. The rate was thought to be 25% or less. Therefore, a smaller liquid crystal element having a size of 10 μm or less has been regarded as unrealistic because of a reduction in aperture ratio. On the other hand, considering reproduction of a hologram as an example, the positional accuracy of the reproduced image depends on the positional accuracy of the hologram, and when precise position setting of the reproduced image is necessary, the positional accuracy of the hologram diffraction pattern itself is necessary. Become. The spatial frequency of the hologram diffraction pattern decreases as a sine function of the crossing angle between the reference light and the object light. Therefore, the pitch of the diffraction pattern can be increased by reducing the intersection angle. However, the pitch dimension and the positional accuracy of the diffraction pattern are essentially independent, and the allowable positional error of the diffraction pattern may be much smaller than the half wavelength distance of the spatial frequency of the diffraction pattern depending on the situation. Here, consider the case where a hologram is formed using a liquid crystal element to reproduce an image. From the viewpoint of pixel formation, it is easier to reduce the crossing angle between the object light and the reference light to roughen the pitch of the diffraction pattern. Fine pixels are required to accurately reproduce the position of the reproduction pattern. Moreover, even if the electrode has a smaller dimension than the thickness of the liquid crystal layer, the aperture ratio is reduced and the light utilization efficiency is extremely reduced if the gap remains constant. In order to clearly display a three-dimensional image of an object, the diffraction pattern must be precisely created and the area of the diffractive element must be large enough. In order to create a diffraction pattern with precision, it is necessary to make the electrode itself for forming a diffraction pattern finer than the pitch of the diffraction pattern to accurately reproduce the pattern. As described above, in order to reproduce a clear stereoscopic image at an accurate position, it is necessary to reproduce the precise shape and precise position of the pattern independently of the pitch of the diffraction pattern. Independently of the above, a fine pixel having a fine dimension less than the thickness of the liquid crystal layer is required. Although the above requirement seems to be unrealizable at first glance, it can be realized by the following implementation. The first measure is to control the liquid crystal layer immediately below the gap between the electrodes. Conventionally, this area has been abandoned to be controlled by the electrodes, but it is considered to enable driving of this area. As the size of the drive electrode is reduced, the rate of protrusion of the lines of electric force to the peripheral portion increases. This effect is greatly advantageous when the electrode size is small compared to the thickness of the liquid crystal layer. When the electrode gap size is set to the minimum fixed value, the ratio of the electrode size can be reduced to the same size or less, but the ratio of the gap in this case is the square of the size ratio, which is better than the electrode area. growing. However, with such a structure, the electrode pitch dimension for pixel formation can be minimized.

[0008]

The effect of the electric field formed by the electrodes on the surroundings when the fine pixel electrode group drives the liquid crystal molecule group can be considered by using the principle of superposition, and the electric field distribution immediately below the electrode gap is Is controlled by the vector sum of the electric fields formed individually by the multiple electrodes of In such a state, only one pixel is turned on (lighting state), and surrounding pixels are turned off.
If you try to drive it to F (light off state), this ON
The pixel to be turned off is pulled off by the surrounding OFF electric field.
It is buried in the electric field and does not light up. However, if a plurality of these electrodes are adjacently connected and turned on,
The electrode group region can be turned on by overlapping electric fields.
That is, by driving a plurality of pixels formed by an electrode group having electrodes and electrode gaps finer than the liquid crystal layer thickness adjacent to each other, the minimum pitch of diffraction pattern formation does not exceed the liquid crystal layer thickness limit. It becomes possible to set the pattern formation position and the pattern formation on a finer scale than the liquid crystal layer thickness. When the fine electrodes are adjacent to each other and have the same potential, the electrode gap becomes an overlap between both electric fields, and a connection equipotential surface is formed so as to smoothly connect the equipotential surfaces under the electrode near the electrode gap. The liquid crystal molecular layer is driven by the combined electric field including the pixel electrode group and the gap due to the coupling drive effect of the subdivided electrodes, and the problem of the aperture ratio is solved.
Another effect is that the contrast is distributed to the resolution. By making the electrode width and the gap finer, the ratio of the electrode cover area to the liquid crystal area is reduced, but the electric force lines are widened for driving including the electrode gap area, and the liquid crystal drive area ratio is improved. Instead, the electric flux density, that is, the strength of the electric field is weakened. The electric field strength can be improved by increasing the voltage applied to the electrodes, but the ratio of the spatially modulated values of the composite electric field controlled to the individual electric potentials of the electrodes is not improved by the voltage enhancement. The electrode potential of the fine structure electrode is set to be turned ON / OFF alternately for each electrode, and the electrode dimension is set from a very large stage (W stage) of 100 times or more the liquid crystal layer thickness to a similar stage. (It is set as M steps), and further, it is changed to a step of 1/100 of the thickness (which is set as N steps). The electric field intensity immediately below the center of the electrodes at the W stage is approximately equal to the value (V / d) obtained by dividing the voltage V applied to the electrodes sandwiching the liquid crystal layer by the thickness d of the liquid crystal layer. In this case, the electric field strength is set to a relative value of 1, and the modulation coefficient is set to 1. When the electric field right under the center of the ON pixel is Eon and the electric field right under the center of the OFF pixel is Eoff, the electric field right under the center of the gap is 0, and the average electric field in the entire liquid crystal area is (Eon + 0 + Eoff + 0) / 4. At N stages, which are extremely fine pixels, the liquid crystal driving electric field and Eon, which are alternately arranged at the W stage,
As a result of the overlap of the electric field 0 and Eoff in the gap, the effect of the spatial electrode structure disappears almost completely, and a uniform (E
on + Eoff) / 4. In M stage,
The effect of the electrode structure on the liquid crystal layer remains sufficiently, and the electric field is spatially modulated. However, due to the influence of the adjacent electrodes, the peripheral electric fields of the pixel are pulled by the electric fields adjacent to each other. In the intermediate stage between M and N (MN stage), the electric field undergoes spatial modulation, but the modulation rate decreases as a result of the tension between Eon and Eoff. This decrease in the modulation factor means a decrease in the contrast of the modulation element by controlling the liquid crystal molecules. Multiple electrodes miniaturized at the MN stage are connected to form M
Create a pixel area with the same dimensions as the stage. The spatial arrangement of the pixel regions is similar to that in the M-stage state, and the electric field of each part of the fine pixel is set so that the electric field distribution in the portion corresponding to the M-stage gap electrode region becomes equal to the M-stage. The M stage approximated by using the fine pixel structure of the MN stage is referred to as M ′ stage. In the spatial modulation pattern Pm of the electric field formed by the M-stage electrode structure, the minimum resolution of the formed pattern is about the thickness of the liquid crystal layer, but the pattern Pm 'created in the M ′ stage is actually the thickness of the liquid crystal layer. Since the shape and position can be finely trimmed with the size of the fine pixel in the MN stage smaller than d, the resolution is superior to the pattern Pm in the M stage. On the contrary, since the M′-stage composite pixel has an electrode gap of about several tens of percent of the area, the M-stage electric field filled with actual electrodes is weakened, and Pm ′ is eventually Although the resolution is higher than the Pm pattern, the contrast is reduced,
However, the structure is suitable for applications in which resolution is more important than contrast, and is particularly effective when forming a diffraction pattern with a liquid crystal element.

[0009]

[First Embodiment] The present invention will be described in detail below with reference to embodiments. 1 is a structural diagram of a liquid crystal device having a fine electrode structure according to a first embodiment of the present invention. 12 and 18 are transparent substrates, which are usually made of glass, and if necessary, sapphire / crystal / plastic substrates. Reference numerals 14 and 16 are transparent electrodes formed on the surface of the transparent substrate, and titanium oxide, tin oxide, indium oxide, or a mixture thereof is used. 11
Is the liquid crystal layer thickness, 13 is the electrode width, and 15 is the electrode gap, where W ≦ H ..., Where H is the substrate gap, W is the electrode gap, and S is the gap distance between adjacent electrodes.・ ・ ・ ・ ・ ・ ・ ・ 1.1 W ≤ S ・ ・ ・ ・ ・ ・ ・ ・ 1.2 ing. When W is made fine, that is, when W << H, the positional accuracy of the pattern formed by the liquid crystal element can be set extremely finely. By setting W ≦ S, it becomes possible to control the liquid crystal layer in the electrode gap region by utilizing the protrusion of the lines of electric force from the electrode with respect to the electrode gap. Since the electrode gap is wide in a normal liquid crystal element structure, the electric field in the gap is weakened and the liquid crystal layer is left undriven. By satisfying both conditions 1.1 and 1.2, the electric field in the electrode gap can be smoothly connected to the electric field immediately below the adjacent electrodes. The main purpose of introducing the above 1.1 is to achieve the pattern position accuracy of the diffraction element. 2 and 3 are views for explaining the effect of improving the pattern position accuracy, in which 21 is an upper substrate made of a transparent insulator, 29 is a lower substrate, and 23 and 28 are formed on the substrate surface. Transparent electrodes, 24 and 26 are cross sections of the equipotential surface in FIG. 2, and 34 and 36 are cross sections of the equipotential surface in FIG.
2 and 3 show the same liquid crystal device, and the difference is the applied voltage pattern of the electrodes. The position of ON potential is 1 in the horizontal direction
The electrodes are shifted by the amount corresponding to the electrodes, and the equipotential lines are naturally shifted by the amount corresponding to one electrode. That is, although the resolution of the electric field pattern is limited by the thickness of the liquid crystal layer, the positional accuracy of the pattern itself is determined by the pitch of the fine electrodes independently of the thickness of the liquid crystal layer, which can be set finer than the thickness of the liquid crystal layer.

[Second Embodiment] FIG. 4 is a diagram for explaining a lateral electric field effect in a fine pixel group when conditions 1.1 and 1.2 are simultaneous. FIG. 4 shows the aspect of the electric field distribution in the case where the electrode size and the electrode gap are changed with the same liquid crystal layer thickness. In the state of FIG. 4A, 42 and 43 are pixel electrode portions having a conventional size, and 41 is a pixel shape when the electrode portion 42 is ON. The electric field in the portion 42 immediately below the electrodes is uniform and constant regardless of the location, and only the peripheral portion is slightly weakened.
Reference numeral 45 represents the shape of the electrode portion when the electrode size is reduced (B) while maintaining the electrode gap under the condition of the same liquid crystal thickness and the same applied voltage, and 44 represents the pixel shape when the electrode portion 45 is ON, 4
6 is a pixel gap. Since the electrode size is reduced while keeping the gap constant, the ratio of the area directly under the electrode to the entire area, that is, the aperture ratio is significantly reduced by changing the condition (A) to the condition (B). Further, for the pole shape 42, the pixel 4
In the case of the shape of No. 1, the ON range is smaller than that of the electrode because the electric field in the peripheral portion is weakened. Electrode part shape 4 under condition (B)
The area reduction ratio of the pixel 44 with respect to 5 is larger than the area reduction ratio of the pixel 41 with respect to the electrode shape 42 under the condition (A).

[Third Embodiment] FIG. 11 shows a structure of a fine pixel electrode and a gap.
7 shows an electric field distribution in the case of pixel connection driving. In FIG. 11, reference numerals 1101 and 1109 denote upper and lower electrode substrates, respectively.
102 is a common timing electrode 1103, 1104-1
105/1106/1107/1108/1109/1
110, 1111, and 1112 are segment electrodes formed on the surface of the lower substrate. Between the large-sized segment electrodes 1103 and 1104 and the counter electrode 1102,
The OFF voltage and the ON voltage are applied to the remaining electrodes 1105, 1106, and 1107, respectively.
An OFF voltage is applied to 1106. As is clear from the state of the equipotential lines, when the potentials of the adjacent fine pixel electrodes are equal, the electric field in the gap is smoothly connected.

Fourth Embodiment FIG. 5 is a diagram for explaining the pixel size, the positional accuracy of the formed pattern, and the spatial noise component. In FIG. 5, 511 and 512 are rough pixel electrodes and 5
Reference numerals 21 and 522 are patterns that should be originally formed with rough pixels. 531 and 532 are fine electrodes, and 541 and 54 are
Reference numeral 2 indicates a pattern to be formed by the fine pixel electrode. The spatial noise component corresponds to the difference between the pattern to be formed and the colored pixel portion. Although spatial noise components are reduced due to the miniaturization of pixels, it can be seen that the position of the pattern can be set freely by the pitch of the pixel electrodes. Rough pixel 51
The pitch of 1.512 is similar to the width and spacing of the pattern to be formed, but with this, a smooth pattern 521.
It is difficult to reproduce 522. In the case of the fine pixels 531 and 532, similar patterns 541 and 542 can be reproduced, and it can be seen that miniaturization of the pixel electrodes is effective for highly accurate hologram diffraction pattern reproduction.

[Fifth Embodiment] FIG. 9 is a diagram showing a structure in which a two-terminal switching element is combined with an embedded electrode, and FIG. 10 is a diagram showing the wiring structure of FIG. In FIG. 9, reference numeral 91 is an upper substrate, 99 is a lower substrate, 96 is an upper electrode, 94 is a lower electrode, 98 is a metal-embedded wiring, and 97 is a connection structure of an electrode also serving as a switching element and a wiring. The bases 91 and 99 are transparent glass substrates, the electrodes 96 are transparent electrodes, and 98 is metal wiring such as aluminum or tantalum. In order to form the buried metal wiring, the glass substrate is etched with hydrofluoric acid HF, and after forming the metal thin film, an oxide film or a thin insulating film made of an organic thin film is formed on the surface. The surface of the substrate is flattened by covering it with an insulating material, a contact hole is opened in the insulating material, and the transparent electrode is connected through a thin insulating film. In FIG. 10, reference numeral 106 denotes a buried metal wire, and 104
Is an insulating film. 108 is a filling insulating material for flattening.
102 is a transparent electrode. The electrode 102 can be a metal or a transparent electrode. The filling material 108 is particularly necessary for flattening the substrate of the fine structure liquid crystal device. As the insulating film 104, tantalum oxide, aluminum oxide, or an organic film can be used. MIM with metal electrode 106, insulating film 104, and electrode 108
It forms a (metal / insulator / metal) structure and functions as a two-terminal switching element. That is, the current does not flow below the threshold voltage, and the current flows suddenly above the threshold voltage. Due to this action, drive crosstalk can be suppressed. The passive embedded electrode structure has an electrode 102 and an insulating thin film 104.
The contact hole is removed. Suitable for simpler and finer structures than active switching structures.

[Sixth Embodiment] FIG. 6 shows an embodiment in which the present liquid crystal light modulation element is used as an electronically controlled real-time diffractive element to control the traveling direction of laser light and perform a condensing action. As a holographic scanner, there was a method of printing a hologram on a rotating disk and scanning the laser light by rotating the disk, but this disk rotation is mechanically changed by pattern deformation movement by electronic control of the liquid crystal hologram pattern. Optical scanning is possible without moving parts. Theoretically, one modulation element fulfills the function, but by combining a plurality of modulation elements, the deflection angle of light can be widened and the light utilization efficiency can be improved. In FIG. 6, reference numeral 62 is a laser light source, 64 and 66 are optical systems including a lens for expanding and collimating an optical beam, 68 and 69 are light modulating elements of the present invention, and 63 and 64 are liquid crystal light modulation. A control circuit including a drive signal source and a drive circuit for the element, and 61 is a convergence point of light. The laser 62 may be a gas laser or a semiconductor laser, but the semiconductor laser is effective because of its small volume. The liquid crystal light modulation elements 68 and 69 are electronically controlled by the signals of the control circuits 63 and 64, and the laser light is directed and focused. If a thermal paper or a thermal ribbon and a paper are arranged at the light converging point and the light is two-dimensionally scanned and the light is condensed and controlled, the printer becomes a thermal printer. Similarly, if an optical recording medium is arranged at the light converging point 61, it becomes a writing / reading mechanism for completely solidifying the optical disk memory or the optical card. As in the conventional structure, if a beam splitter is placed between the lens 66 and the modulation element 68 and the returning light is detected, the optical recording medium can be read. In any case, the mechanism that has been mechanically scanned by a rotating mirror or a vibrating mirror can be completely solidified or partially solidified without mechanical moving parts, and compared with the conventional one in terms of system volume, weight and response speed. And become excellent. The liquid crystal light modulation element can utilize various aspects of phase modulation / intensity modulation of light by the liquid crystal element, rotation modulation of the deflecting surface, or a combination thereof.

[Seventh Embodiment] FIG. 7 is for explaining the pattern position movement of the optical modulator used in FIG. In FIG.
75 and 76 are liquid crystal light modulation elements, 73 and 74 are examples of diffraction patterns formed by liquid crystal elements, 75 and 76 are masking patterns, and 71 and 72 are incident lights. The incident light 71 emitted from the lens 66 of FIG. 6 is diffracted by the diffraction pattern 73, and the diffracted light becomes incident light 72 of the element 76, which is diffracted and condensed by the pattern 74 and reaches 61.

Eighth Embodiment FIG. 12 shows a system configuration example of a stereoscopic television using the liquid crystal element of the present invention. 1210 is
The light source, 1240 is a beam splitter, 1242.1
244 and 1246 are mirrors and 1212, 1213 and 1214
Is an image pickup device, 1216 is a signal synthesizing device 1218 is a transmission line, 1220 is an optical modulator according to the present invention, 1222 is a laser light source 1224 is a spatial filter using a liquid crystal element. The light emitted from the laser light source is the beam splitter 1240.
The object is irradiated after being divided by the mirror, while the mirror 1242
The light is reflected by 1244 and 1246 and becomes reference light, which is guided to elements inside the image pickup devices 1212, 1213, and 1214. Multiple holograms are formed on the image sensor,
Combine the results. If necessary, a spatial filter is used to cut off extra stray light. This can also be electronically controlled by using a liquid crystal, and it is possible to flexibly respond to the usage situation. The use of a plurality of image pickup elements is effective for expanding the viewing angle for stereoscopic viewing and collecting color information.
Although only one is shown, a plurality of light modulators for reproduction can be used in parallel and can be effectively used for improving the viewing angle of reproduced images and imparting colors. FIG. 8 shows pixel correspondence of a multi-imaging device for improving the definition in stereoscopic imaging. 810 is a beam splitter, 812 is an imaging device and a set of pixels A, and 814 is an imaging device and a screen composed of a set of pixels B. 816 are both A
The image is a combination of B. An image 812 with slightly different pixel positions from the image divided by the beam splitter,
14 is collected by an inexpensive image pickup device, a high-definition image 816 is synthesized by superimposing image data, and used for image reproduction.

【The invention's effect】

(1) The effect of the present invention is that, firstly, a high aperture ratio is realized by miniaturizing the electrodes. Condition (C) of FIG.
In the condition (B), the electrode size is further reduced, and the structure is such that the erosion of the electrode is almost 100% and the gaps of the fine pixel electrodes are filled. The lines of electric force swell in the lateral direction, and the electric field directly below the electrodes is weakened by that amount, but the electric field in the electrode gap is the vector sum of the surrounding electric fields, so all the surrounding electrodes are "ON". In this case, the electric field in the gap is also close to "ON", and when all the surrounding electrodes are "OFF", the electric field in the gap is also close to "OFF". That is, the electric field strength = 0 when the size of the electrode gap is large, but the electric field can be applied by reducing the gap distance. The electric field weakened by the swelling of the lines of electric force can be reinforced by increasing the applied voltage. As a result, it is possible to turn on the liquid crystal directly below the electrode, which was almost 100% eaten by the electrode's erosion, and further increase the applied voltage to expand and connect the pixels to drive the liquid crystal in the electrode gap. become able to do. As a result, the problem of lowering the aperture ratio, which has been regarded as a fatal defect of the fine pixel liquid crystal element, can be solved by improving the aperture ratio. This is an effect of multiple connection driving of pixels finer than the liquid crystal layer thickness originally considered unnecessary. (2) As a second important effect of the present invention, in the pixel forming electrode condition (C) of FIG. 4, it is possible to drive by connecting a plurality of adjacent pixel groups as a driving condition. is there. Even if one fine pixel is individually driven, the driving effect is little exhibited. Includes a gap area defined by 48 by connecting fine pixels as shown in FIG.
It was possible to give the effect that the entire surrounding electrode group was turned off. The liquid crystal layer in this region consequently forms a continuous OFF region. On the contrary, the electrode 49 is ON, and the ON region pixel 4 connected including the gap 48 in the vicinity is connected.
It was possible to form 7. (3) Third, in order to realize a liquid crystal light modulation element, it was necessary to miniaturize pixels and improve the modulation rate. However, by adopting a buried wiring type structure in which the width of the electrode is extremely narrowed, It is now possible to provide a specific method and structure for pixel miniaturization. At this time, a structure using a metal wire for ensuring conductivity is also meaningful. In this case, since the metal wire does not transmit light, the liquid crystal layer can be modulated exclusively by using the electric field in the electrode gap. Such a structure is particularly effective when a ferroelectric liquid crystal is used. This is because the liquid crystal element has a strong spontaneous polarization, and a large current must be passed when switching the direction of molecules. In order to realize a liquid crystal light modulation element, it is necessary to arrange a large number of fine pixels in a matrix to drive it, but high-performance spatial light using a super twist (STN) structure or a ferroelectric liquid crystal element (FLC). It can be said that the modulator element can be provided is a remarkable effect. Because the ferroelectric liquid crystal element has a liquid crystal layer thickness of 1.5.
It can be driven at less than μm and is a strong candidate for pixel miniaturization.
Further, in consideration of improvement in contrast, a structure in which pixels are selectively driven in combination with an active switching element is also effective.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, which is a configuration diagram of a liquid crystal element.

FIG. 2 is an explanatory diagram showing an embodiment of the present invention and is an electric field distribution diagram.

FIG. 3 is an explanatory diagram showing an example of the present invention, and is an electric field distribution diagram.

FIG. 4 is an explanatory diagram showing an example of the present invention and is a diagram showing a lateral electric field effect.

FIG. 5 is an explanatory view showing an embodiment of the present invention, showing the positional accuracy of fine pixels and the figure error.

FIG. 6 is an explanatory view showing an embodiment of the present invention, showing an embodiment of a liquid crystal optical scanning mechanism.

FIG. 7 is an explanatory view showing an embodiment of the present invention, showing a pattern of a liquid crystal light diffraction element using a plurality of links.

FIG. 8 is an explanatory view showing an embodiment of the present invention, showing a concavo-convex electrode structure.

FIG. 9 is an explanatory view showing an embodiment of the present invention, showing a structure of an active liquid crystal element electrode substrate.

FIG. 10 is an explanatory view showing an embodiment of the present invention, showing a cross section of an active liquid crystal element electrode substrate.

FIG. 11 is an explanatory diagram showing an example of the present invention and is an electric field distribution diagram.

FIG. 12 is an explanatory diagram showing an embodiment of the present invention, showing an imaging transmission / reproduction system.

[Explanation of symbols]

 12 upper electrode substrate 14 upper electrode 16 lower electrode 18 lower electrode substrate

Claims (12)

[Claims] 1. A pair of transparent substrates provided with a group of fine electrodes arranged in a striped pattern and opposed to each other, and a liquid crystal layer sandwiched between the transparent substrates. The fine electrodes are formed by connecting a plurality of adjacent electrodes. Is applied, and the electrode gap region surrounded by the plurality of adjacent microelectrodes is driven simultaneously with the region directly below the electrode by the lateral electric field of the connection application ridge, thereby forming a continuous spatial modulation pattern. element. 2. The photoelectric modulation element according to claim 1, wherein the width of the fine electrode is smaller than the thickness of the liquid crystal layer. 3. The fine electrodes are strip-shaped transparent electrodes, which are formed on a transparent insulating substrate, and the liquid crystal layer sandwiched between the substrates is divided into a plurality of pixels arranged in a matrix and is shorter than the thickness of the liquid crystal layer. The light modulation element according to claim 1, wherein a plurality of the adjacent pixels are connected and driven to form a spatial modulation pattern depending on the electrode width and the electrode gap. 4. The fine electrode is a linear metal electrode, is formed on the surface of a transparent insulating substrate, and the liquid crystal layer sandwiched by the substrate is divided into a plurality of pixels arranged in a matrix, and the width and gap of the electrode are The light modulation element according to claim 1, wherein the spatial modulation pattern is formed by driving a plurality of pixels which are smaller than the thickness of the liquid crystal layer and which are formed by electrodes sandwiching the liquid crystal layer. 5. The fine electrode is a linear electrode, and the electrode is formed on the surface of a transparent insulating substrate by periodically changing the height of the central axis of the linear electrode in a wavy manner as a function of location, and sandwiching the substrate. The divided liquid crystal layer is divided into a plurality of pixels arranged in a matrix, the width and gap of the electrodes are smaller than the thickness of the liquid crystal layer, and a plurality of pixels formed by electrodes sandwiching the liquid crystal layer are connected and driven. The light modulation element according to claim 1, wherein the light modulation element has a structure that forms a spatial modulation pattern. 6. The light modulation element according to claim 1, wherein the liquid crystal layer sandwiched between the fine electrodes has a twisted nematic structure in which the liquid crystal layer is oriented in a constant direction with respect to the substrate. 7. The light modulation element according to claim 1, wherein the liquid crystal sandwiched between the fine electrodes is a ferroelectric liquid crystal, and the liquid crystal has a structure in which the liquid crystal is aligned in a certain direction with respect to the substrate. 8. The liquid crystal sandwiched between the fine electrodes is a ferroelectric liquid crystal, the liquid crystal is aligned in a certain direction with respect to the substrate, and three-dimensionally inside the liquid crystal layer by electrodes and electrode gap groups finer than the liquid crystal layer thickness. 2. The light modulation element according to claim 1, wherein the molecular alignment state of the ferroelectric liquid crystal layer is controlled by utilizing the electric field controlled by the above. 9. The liquid crystal is an antiferroelectric liquid crystal, and the liquid crystal sandwiched between fine electrodes is an antiferroelectric liquid crystal, and the liquid crystal is aligned in a certain direction with respect to a substrate, and an electrode finer than a liquid crystal layer thickness. 2. The light modulation element according to claim 1, wherein the electric field that is three-dimensionally controlled inside the liquid crystal layer by the electrode gap group is used to control the molecular orientation state of the anti-dielectric liquid crystal layer. 10. The liquid crystal element is an active addressing type liquid crystal element in which a switching element is provided for each fine electrode, and two-terminal switching connected to the fine electrode via a metal wiring embedded in a substrate and an insulator thin film. The light modulation element according to claim 1, which has an element structure. 11. A transparent insulating substrate having fine electrodes formed thereon and a liquid crystal layer sandwiched therebetween, the liquid crystal layer being partitioned into a plurality of pixels arranged in a matrix, and the width and gap of the electrodes are the liquid crystal layer. Of a plurality of light modulation elements that are shorter than the thickness of the liquid crystal layer and drive a plurality of pixels formed by electrodes sandwiching the liquid crystal layer, and drive the plurality of light modulation elements with equal electrical signals. The light modulation element according to claim 1, wherein the light modulation element is a light modulation element. 12. A transparent insulating substrate having fine electrodes formed thereon and a liquid crystal layer sandwiched therebetween, the liquid crystal layer being divided into a plurality of pixels arranged in a matrix, and the width of the electrode is the thickness of the liquid crystal layer. Shorter than the above, by stacking a plurality of light modulation elements for driving a plurality of pixels formed by electrodes sandwiching the liquid crystal layer, and driving them with different electric signals, the spatial modulation pattern of the light wave front is three-dimensionally The light modulation element according to claim 1, wherein the light modulation element is formed.