JP2022124962A - Liquid crystal optical modulator, liquid crystal display device, and stereoscopic image display device - Google Patents

Abstract

Kind Code: A1 A liquid crystal light modulator of a simple configuration is provided which can display a desired two-dimensional pattern of fine pixels without using a drive circuit. A liquid crystal optical modulator (10) includes a liquid crystal layer (20), and an upper electrode (41) and a lower electrode (31) for applying a voltage vertically across the liquid crystal layer (20). A common electrode 32 having a plurality of openings 32a formed therebetween and an electrode interlayer insulating film 52 for insulating the common electrode 32 and the lower electrode 31 are further laminated. By connecting the common electrode 32 to the same potential as the upper electrode 41 and applying a voltage, an electric field is generated in the liquid crystal layer 20 limited to the region above the opening 32a. [Selection drawing] Fig. 1

Description

Application for application of Article 30, Paragraph 2 of the Patent Act (1) The 67th Spring Meeting of the Japan Society of Applied Physics, published by the Japan Society of Applied Physics on February 28, 2020, 12a-PA1-7 , 2020, p. 03-047 (2) Proceedings of The 57th International Display Week Symposium published online by the Society for Information Display on August 3, 2020, SID Symposium Digest of 1, Technical Papers 1, Vol. (3) Oral presentation at The 57th International Display Week Symposium held online by Society for Information Display on August 6, 2020 (Lecture number: 3-5) (4) October 9, 2020 The Institute of Image Information and Television Engineers Technical Report, Volume 44, Number 26, IDY2020-35, pp. Presented on 17-20 (5) Oral presentation at the invited lecture of the Institute of Image Information and Television Engineers Information Display Study Group "Display General" held online by the Institute of Image Information and Television Engineers (ITE) on October 16, 2020 (6) 2020 2020 Japanese Liquid Crystal Society Online Research Conference Proceedings, 2I03, 2020, pp. 2020, published online by the Japanese Liquid Crystal Society on October 22nd. 61-62 (7) Oral presentation at the 2020 Japanese Liquid Crystal Society Online Research Conference held online by the Japanese Liquid Crystal Society on October 30, 2020 (lecture number: 2I03) (8) December 2020 Proceedings of the International Display Workshops, Volume 27, LCT7-1, 2020, pp. Proceedings of the International Display Workshops, Volume 27, LCT7-1, 2020, pp. Announced in 91-94

(9) Oral presentation at The 27th International Display Workshops (IDW'20) held online by Display International Workshop on December 10, 2020 (lecture number: LCT7-1)

The present invention relates to a liquid crystal optical modulator, and a liquid crystal display device and a stereoscopic image display device using this liquid crystal optical modulator.

A spatial light modulator (SLM) is a device that spatially modulates the phase and amplitude of light by arranging optical elements (light modulation elements) as pixels two-dimensionally in a matrix. , recording technology, and laser processing. Spatial light modulators, for example, apply liquid crystals or magneto-optical materials to optical elements to change the polarization direction of light (optical rotation), or have a movable micromirror for each pixel to reflect light. A DMD (Digital Mirror Device) system that changes the direction has been developed, and research has been conducted on miniaturization of pixels for higher definition and miniaturization. Among them, spatial light modulators that use liquid crystals as optical elements, which have a large optical rotation angle, that is, a high degree of optical modulation, and which can be produced relatively easily, are widely used in liquid crystal displays (LCDs) and the like. . Spatial light modulators are required to have more pixels and higher definition for application to stereoscopic image display devices and the like. In order to obtain the field angle, it is desired that the pixel pitch (pixel length) is about 2 μm at maximum, or even finer.

An optical element using liquid crystal (liquid crystal optical element) includes a liquid crystal layer 20 and a pair of electrodes 3 and 4 arranged above and below, as schematically shown in FIG. A voltage is applied across layer 20 to generate a vertical electric field. In order to control the orientation of the liquid crystal molecules 2, alignment films 21 and 22 are provided in contact with the upper and lower sides of the liquid crystal layer 20, respectively. For example, in the case of the twisted nematic (TN) system, the liquid crystal layer 20 in the no-electric-field state, as shown on the right side of FIG. ° Arranged up and down to twist. On the other hand, when a voltage is applied from the electrodes 3 and 4 to generate an electric field perpendicular to the film surface, the liquid crystal molecules 2 stand up vertically along the electric field, as shown on the left side of FIG. ing. Polarizers 71 and 72 are arranged above and below such a liquid crystal optical element in parallel Nicols, and one polarized light component (linearly polarized light) L is incident on the liquid crystal layer 20 via the polarizer 71 . When no voltage is applied to the liquid crystal layer 20, the polarization direction of the transmitted light L is changed by 90°. Light L is transmitted through the polarizer 72 without changing direction.

A spatial light modulator using such a liquid crystal optical element as a pixel (hereinafter referred to as a liquid crystal light modulator) generally has one of a pair of electrodes (electrode 3 on the lower side of the liquid crystal layer 20 in FIG. 5). are two-dimensionally arranged apart from each other as pixel electrodes provided for each pixel, and the other (electrode 4) is provided over the entire surface as an electrode (counter electrode) common to all pixels. The liquid crystal light modulator is provided with a driving circuit having a storage capacitor and a transistor formed of a TFT (thin film transistor) or a MOSFET (metal oxide semiconductor field effect transistor) for each pixel further below the pixel electrode 3. 3 is electrically connected. The pixel electrodes 3 have a predetermined potential difference or the same potential with respect to the counter electrode 4 by the signal line input to the drive circuit, and the liquid crystal layer 20 generates an electric field or no electric field in the region directly above each pixel electrode 3 . becomes. As a result, the light is transmitted through the polarizer 72 for each pixel, resulting in a bright (white) display, or blocked, resulting in a dark (black) display. In addition, since no electric field is generated in the liquid crystal layer 20 above the gap between the pixel electrodes 3, the liquid crystal light modulator is provided with a grid-like black matrix along the boundary between the pixels as a non-aperture. Therefore, miniaturization of the pixels of the liquid crystal optical modulator is mainly restricted by the driving circuit. In particular, LCOS (Liquid Crystal On Silicon)-SLM, in which transistors are formed of MOSFETs, is limited to reflective liquid crystal light modulators (for example, Patent Document 1) because the drive circuit is formed on a Si substrate. , pixels can be more easily miniaturized than TFTs, and have been realized to a pitch of about 3 μm.

On the other hand, in liquid crystal light modulators, as the pixels become finer and the ratio of the thickness of the liquid crystal layer (cell thickness) to the pixel length becomes higher, the effect of leakage electric field between adjacent bright and dark pixels becomes greater. , the contrast of the display is reduced. More specifically, since the counter electrode 4 is formed wider than the pixel electrode 3 partitioned for each pixel, the counter electrode 4 spreads outward to some extent from the pixel electrode 3 of the pixel to which the voltage is applied and extends obliquely. A weak electric field directed toward If the pixel length is short, the oblique electric field reaches the pixel electrode 3 (aperture) of the adjacent non-applied pixel. Further, the electric field also leaks in the in-plane (horizontal) direction between the pixel electrodes 3, 3 of adjacent bright display pixels and dark display pixels. Due to these leakage electric fields, the liquid crystal molecules 2 rise obliquely even in the openings of the pixels to which no voltage is applied, resulting in incomplete display in which the original (complete) dark display or bright display is not obtained.

In order to suppress the leakage electric field between pixels in the liquid crystal light modulator, a liquid crystal light modulator has been disclosed in which a wall made of a dielectric material for partitioning the liquid crystal layer is provided along the boundaries of the pixels (Non-Patent Documents 3 and 4). ). Alternatively, a liquid crystal light modulator is disclosed in which unevenness is formed on a transparent substrate, a counter electrode is formed thereon, and the counter electrode protrudes so that the thickness of the liquid crystal layer is minimized at the boundary between pixels. (Patent Document 2). An electric field directed diagonally from the pixel electrode of a pixel to which a voltage is applied to the counter electrode and an electric field directed laterally to the pixel electrode of the adjacent pixel are blocked or trapped by the counter electrode protruding from the non-opening portion, and no application is made. It becomes difficult for the electric field to reach the apertures of the pixels, and the leakage electric field is weakened.

Japanese Patent No. 4643786 JP 2020-64192 A

Tomoyuki Mishina, “Research trend of spatial image reproduction type stereoscopic video”, NHK Giken R&D, No. 151, p. 10-17, May 2015 Fai Mok, Joseph Diep, Hua-Kuang Liu, Demetri Psaltis, “Real-time computer-generated hologram by means of liquid-crystal television spatial light modulator”, Optics Letters, Volume 11, Issue 11, pp. 748-570, 1986 Yoshitomo Isomae, Yosei Shibata, Takahiro Ishinabe, Hideo Fujikake, “Design of 1-μm-pitch liquid crystal spatial light modulators having dielectric shield wall structure for holographic display with wide field of view”, Optical Review, Volume 24, Issue 2, pp. 165-176, April 2017 Yoshitomo Isomae, Yosei Shibata, Takahiro Ishinabe, Hideo Fujikake, “Experimental study of 1-μm-pitch light modulation of a liquid crystal separated by dielectric shield walls formed by nanoimprint technology for electronic holographic displays”, Optical Engineering, Volume 57, Issue 6 , 061624, June 2018

In the development of liquid crystal light modulators with a narrow pixel pitch, such as those disclosed in Non-Patent Documents 3 and 4 and Patent Document 2, especially when current MOSFETs, etc., that make up drive circuits are miniaturized, for example, light and dark pixels An operation experiment is conducted with a liquid crystal light modulator having a fixed pattern in which the pixels are alternately arranged. Such a liquid crystal light modulator has a one-dimensional light-dark pattern in which strip-shaped pixel electrodes are arranged in stripes (see, for example, Non-Patent Document 4), or the above-mentioned It is limited to a bright and dark pattern of pixel electrodes in which electrodes arranged in stripes are arranged in two rows in the longitudinal direction. Especially for ferroelectric liquid crystal (FLC), unlike nematic liquid crystal, a general orientation simulation method has not been established, so an experimental device is required for verification of narrow pixel pitch. Further, in the development of stereoscopic image display devices, spatial light modulators in which a large number of pixels are two-dimensionally arranged are required. A two-dimensional light-and-dark pattern of three or more columns is realized, for example, by forming a wiring connected to an external power source with an insulating film having contact holes formed under the pixel electrode sandwiched therebetween. is not easy to make for an experimental machine.

SUMMARY OF THE INVENTION The present invention has been devised in view of the above problems. An object of the present invention is to provide a liquid crystal display device and a stereoscopic image display device.

That is, a liquid crystal optical modulator according to the present invention comprises a liquid crystal layer, and an upper electrode and a lower electrode for applying a voltage in the vertical direction with the liquid crystal layer sandwiched therebetween. a common electrode having a plurality of openings; and an inter-electrode insulating film for insulating the common electrode from the lower electrode.

With such a configuration, the liquid crystal optical modulator is in a state in which the lower electrode is provided only in the opening of the common electrode due to the common electrode provided closer to the liquid crystal layer than the lower electrode, and the opening pattern of the common electrode provides a desired can be a two-dimensional light-dark pattern.

A liquid crystal display device according to the present invention includes the liquid crystal optical modulator and a polarizer arranged above or below the liquid crystal optical modulator, and the side on which the polarizer is arranged is irradiated with light. to display the image. Alternatively, the liquid crystal display device according to the present invention includes the liquid crystal optical modulator and two polarizers arranged above and below the liquid crystal optical modulator, and is irradiated with light from either the upper side or the lower side. to display the image on the other. With such a configuration, the liquid crystal display device can display a desired image by the aperture pattern of the common electrode of the liquid crystal optical modulator.

A stereoscopic image display device according to the present invention is connected to the liquid crystal display device, a light source for irradiating the liquid crystal display device with light, and an upper electrode, a lower electrode, and a common electrode of a liquid crystal light modulator of the liquid crystal display device. a power source; With such a configuration, the stereoscopic image display device can display a stereoscopic image based on a desired two-dimensional pattern.

According to the liquid crystal optical modulator of the present invention, a liquid crystal display device having a simple configuration capable of displaying a desired image without a driving circuit can be obtained. can also be configured. According to the liquid crystal display device and stereoscopic image display device of the present invention, a desired image can be displayed with fine pixels.

1 is an external view for explaining the structure of a liquid crystal optical modulator according to a first embodiment of the invention; FIG. FIG. 2 is a schematic diagram for explaining the structure of the liquid crystal optical modulator according to the first embodiment of the invention, and is a partial cross-sectional view of FIG. 1; FIG. 2 is a plan view of a common electrode of the liquid crystal optical modulator shown in FIG. 1; 2 is a schematic diagram of a display pattern of a liquid crystal display device including the liquid crystal optical modulator shown in FIG. 1. FIG. FIG. 4 is a schematic diagram for explaining the operation of a liquid crystal optical element in a twisted nematic liquid crystal optical modulator. It is a figure explaining the change of the polarization characteristic by the difference in phase difference. FIG. 2 is a schematic diagram illustrating another structure of the liquid crystal optical modulator according to the first embodiment of the present invention, and is a partial cross-sectional view of FIG. 1; FIG. 2 is a schematic diagram illustrating another structure of the liquid crystal optical modulator according to the first embodiment of the present invention, and is a partial cross-sectional view of FIG. 1; 1A and 1B are schematic diagrams for explaining the structure and operation of a liquid crystal display device including a liquid crystal optical modulator according to a first embodiment of the present invention; 1 is a schematic diagram illustrating the structure of an integral-type stereoscopic image display device according to an embodiment of the present invention; FIG. 1 is a schematic diagram illustrating the structure of a holographic stereoscopic image display device according to an embodiment of the present invention; FIG. It is a schematic diagram explaining the structure and operation|movement of the liquid crystal display device provided with the liquid crystal optical modulator which concerns on the modification of 1st Embodiment of this invention. FIG. 5 is a schematic diagram illustrating the structure of a projection display device including a liquid crystal optical modulator according to a modification of the first embodiment of the invention; FIG. 2 is a schematic diagram for explaining the structure of a liquid crystal optical modulator according to a second embodiment of the invention, and corresponds to the partial cross-sectional view of FIG. 1; 9 is a time chart of voltages applied to liquid crystal optical modulators according to the second embodiment of the present invention and its modification. FIG. 3 is a schematic diagram for explaining the structure of a liquid crystal optical modulator according to a modification of the second embodiment of the invention, and corresponds to the partial cross-sectional view of FIG. 1; FIG. 7 is a partial cross-sectional view schematically illustrating the structure of a liquid crystal optical modulator according to a third embodiment of the invention; FIG. 10 is a schematic diagram illustrating the structure and operation of a liquid crystal display device including a liquid crystal optical modulator according to a third embodiment of the present invention; FIG. 10 is a schematic diagram illustrating the structure and operation of a liquid crystal display device including a liquid crystal optical modulator according to a third embodiment of the present invention; 9 is a time chart of voltages applied to the liquid crystal optical modulator according to the third embodiment of the present invention; FIG. 4 is a plan view for explaining the shape of a common electrode of a sample of the liquid crystal optical modulator according to the first embodiment of the present invention in plan view, and the observation position of the simulation; Fig. 2 shows potential distribution and liquid crystal orientation in a cross section of a sample of the liquid crystal optical modulator according to the first embodiment of the present invention; Fig. 2 shows potential distribution and liquid crystal orientation in the plane of a sample of the liquid crystal light modulator according to the first embodiment of the present invention; FIG. 2 is a two-dimensional distribution diagram of liquid crystal orientation and transmittance in the plane of a sample of the liquid crystal optical modulator according to the first embodiment of the present invention; FIG. 10 is a plan view for explaining the planar view shape of the common electrode of the liquid crystal optical modulator sample according to the second embodiment of the present invention and its modification, and the observation position of the simulation; It is the potential distribution and the liquid crystal orientation in the cross section of the sample of the liquid crystal optical modulator according to the second embodiment of the present invention. FIG. 10 is a two-dimensional distribution diagram of the transmittance of a sample of the liquid crystal optical modulator according to the second embodiment of the present invention; It is the potential distribution and the liquid crystal orientation in the cross section of the sample of the liquid crystal optical modulator according to the modified example of the second embodiment of the present invention. FIG. 10 is a two-dimensional distribution diagram of transmittance of a sample liquid crystal light modulator according to a modification of the second embodiment of the present invention;

A mode for realizing a liquid crystal optical modulator and a liquid crystal display device according to the present invention will be described with reference to the drawings. The liquid crystal optical modulators and elements thereof shown in the drawings may be exaggerated in size, positional relationship, etc., and may be simplified in shape for clarity of explanation.

[First Embodiment]
As shown in FIGS. 1 and 2, the liquid crystal optical modulator 10 according to the first embodiment of the present invention includes a liquid crystal layer 20, an upper electrode 41 and a lower electrode 31 sandwiching the liquid crystal layer 20 from above and below, and the lower electrode 31 and the liquid crystal. A common electrode 32 having an opening 32 a provided between layers 20 and an inter-electrode insulating film 52 insulating the common electrode 32 and the lower electrode 31 are provided. The liquid crystal optical modulator 10 further includes alignment films 21 and 22 in contact with the upper and lower surfaces of the liquid crystal layer 20 , a transparent substrate 61 above the upper electrode 41 , and a transparent substrate 62 below the lower electrode 31 . The liquid crystal light modulator 10 transmits light (visible light) incident on the entire surface from either the upper side or the lower side and emits it to the other side, and at that time, changes the polarization direction of the light in a predetermined partial area. type spatial light modulator. Also, the liquid crystal optical modulator 10 is applied to a liquid crystal display device that displays the fixed pattern shown in FIG. 4 as an image. For simplicity of explanation, the liquid crystal light modulator 10 is exemplified by a display pattern of 96 pixels in 12 rows×8 columns. Each element constituting the liquid crystal optical modulator according to this embodiment will be described in detail below.

(liquid crystal layer)
The liquid crystal layer 20 is made of a liquid crystal material, and is used in a liquid crystal display such as a twisted nematic (TN) system (see FIG. 5), a vertical alignment (VA) system, or a ferroelectric liquid crystal (FLC) system. Known materials applied to the device can be mentioned. For the liquid crystal layer 20, liquid crystal having positive dielectric anisotropy (p-type liquid crystal) is applied in the TN mode, and liquid crystal having negative dielectric anisotropy (n-type liquid crystal) is applied in the VA mode. ) applies. Here, it is assumed that the liquid crystal layer 20 is of the TN system. In the liquid crystal layer 20 in the no electric field state (initial state), as shown in the right side of FIG. °Because they try to fall in different directions, they are arranged vertically by changing their direction little by little in the in-plane direction. Due to the liquid crystal molecules 2 arranged vertically in a twisted manner, the liquid crystal layer 20 produces a phase difference between mutually orthogonal polarized light components in the transmitted light. On the other hand, in the liquid crystal layer 20, when an electric field is generated in the vertical direction, the liquid crystal molecules 2 stand up with an inclination corresponding to the strength of the electric field, and the phase difference δ of the light passing through the liquid crystal layer 20 becomes zero. The thickness (cell thickness) of the liquid crystal layer 20 is designed in the range of about 0.5 to 5 μm depending on the liquid crystal material and the like so as to obtain desired optical characteristics. In the liquid crystal light modulator 10, which is a transmissive spatial light modulator, it is preferable that the maximum phase difference δ is π (when no electric field is applied in the TN system and when the maximum drive voltage is applied in the VA system). . However, when the cell thickness is large, the response speed of the liquid crystal optical modulator 10 becomes slow.

As shown in FIG. 6, the polarization characteristics of transmitted light change with a period of 2π due to the phase difference δ. When the phase difference .delta. In the liquid crystal layer 20, when the electric field is weak (not maximum), the liquid crystal molecules 2 rise obliquely, and light is modulated with a phase difference of less than π according to the rising angle. In FIG. 5, linearly polarized light is incident on the liquid crystal layer 20. However, in the case where the liquid crystal driving method is the TN method or the VA method (see FIG. 12) as shown in FIG. In order to compensate for the phase difference of light due to the layer 20 , it is preferable that a retardation plate is provided between the upper and lower polarizers 71 and 72 so that circularly polarized light is incident on the liquid crystal light modulator 10 .

(Alignment film)
The alignment films 21 and 22 are provided in contact with the top and bottom of the liquid crystal layer 20 in order to control the orientation of the liquid crystal molecules 2 . In the liquid crystal light modulator 10, the alignment film 21 is formed on the surface of the upper electrode 41 (the surface facing the liquid crystal layer 20), and the alignment film 22 is exposed on the surface of the common electrode 32 and the opening 32a of the common electrode 32. It is formed on the surface of the electrode interlayer insulating film 52 . The alignment films 21 and 22 are organic films such as polyimide or inorganic films such as Si oxide (SiO _x ). It is formed. In the present embodiment, as the TN method, each of the alignment films 21 and 22 is formed with minute grooves or the like along one direction and its perpendicular direction (alignment treatment) on the surfaces (surfaces in contact with the liquid crystal layer 20). If necessary, an alignment treatment is applied so that the liquid crystal molecules 2 stand up while tilting in the same direction when a voltage is applied. For example, polyimide is subjected to orientation treatment by rubbing or UV irradiation after being formed into a film by a coating method, and SiO _x is subjected to orientation treatment simultaneously with film formation by oblique vapor deposition.

(upper electrode, lower electrode)
The lower electrode 31 and the upper electrode 41 are provided to generate a vertical electric field in the liquid crystal layer 20 . In the present invention, a display pattern is formed by a common electrode 32, which will be described later, and both the lower electrode 31 and the upper electrode 41 are shared by all pixels and provided as an integrally continuous film.

Since the liquid crystal optical modulator 10 according to this embodiment is a transmissive spatial light modulator, both the lower electrode 31 and the upper electrode 41 are made of a transparent electrode material so as to transmit light (visible light). . Transparent electrode materials include, for example, indium zinc oxide (IZO), indium-tin oxide (ITO), tin oxide (SnO ₂ ), antimony oxide-tin oxide (ATO), oxide It consists of known conductive oxides such as zinc (ZnO), fluorine-doped tin oxide (FTO), indium oxide (In ₂ O ₃ ), and indium-gallium zinc oxide (IGZO). Alternatively, nanocarbon materials such as graphene and carbon nanotubes, and conductive polymers such as PEDOT/PSS (Poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate)) can also be applied. The electrodes 31 and 41 made of these transparent electrode materials preferably have a thickness of 20 nm or more so as to obtain sufficient conductivity, and are formed by a known method such as a sputtering method, a vacuum deposition method, or a coating method. filmed. Alternatively, the metal electrode material may be formed to a thickness of 10 nm or less so that light can be sufficiently transmitted.

(common electrode)
The common electrode 32 is provided between the lower electrode 31 and the liquid crystal layer 20 in order to prevent the electrode 31 and the electrode 41 from partially generating an electric field in the liquid crystal layer 20 . In other words, the common electrode 32 is formed with an opening 32a so as to leave a region for generating an electric field. In the liquid crystal optical modulator 10 according to the present embodiment, the apertures 32a of the common electrode 32 serve as bright display pixels indicated by white squares in FIG. As shown in FIG. 3, in the present embodiment, the openings 32a are squares each having _a side length la in plan view (xy plane), and are two-dimensionally arranged vertically and horizontally. The aperture 32a is preferably large in order to increase the aperture ratio of the pixel. On the other hand, since the common electrode 32 is not separated, the width (p _x -l _a , p _y -l _a ) between the openings 32a of the adjacent pixels is designed so as not to disconnect. In addition, if the region in which the electric field is not generated for the pixel for dark display is smaller than the thickness (cell thickness) of the liquid crystal layer 20, the leakage electric field from the pixel for bright display is likely to occur. The dark display pixel area is a (2p _x −1 _a )×(2p _y −1 _a ) area above the common electrode 32 (outside the opening 32a). Therefore, it is preferable to design the pixel lengths p _x and p _y in the x and y directions according to the cell thickness.

The common electrode 32 preferably has a thickness of 5 nm or more. On the other hand, regarding the alignment film 22 formed on the common electrode 32, in order to reduce the step at the edge of the opening 32a, and more preferably to flatten the surface, especially when the alignment film 22 is an inorganic film. In other words, the common electrode 32 preferably has a smaller thickness, specifically 20 nm or less. The common electrode 32 is selected from the electrode materials described above so as to transmit light like the lower electrode 31, and is formed by a known method depending on the material, photolithography, etching or lift-off, or It is processed into a desired plan view shape by printing or the like.

(Electrode interlayer insulating film)
The inter-electrode insulating film 52 is provided between the lower electrode 31 and the common electrode 32 to insulate them. The inter-electrode insulating film 52 can be made of a known inorganic insulating material provided in semiconductor elements and the like, and examples thereof include oxide films such as SiO ₂ , MgO and Al ₂ O ₃ , Si ₃ N ₄ and MgF ₂ . The thickness of the inter _- electrode insulating film 52 is designed according to the maximum potential difference between the lower electrode 31 and the common electrode 32 so as not to cause dielectric breakdown. It is preferable that the dielectric constant is about 4) and the thickness is 50 nm or more. On the other hand, as the electrode interlayer insulating film 52 becomes thicker, it is necessary to increase the voltage applied to the liquid crystal optical modulator 10 . Therefore, the thickness of the electrode interlayer insulating film 52 is preferably less than 20% of the thickness (cell thickness) of the liquid crystal layer 20, and is preferably thinner within a range that does not cause dielectric breakdown. As will be described later, since the liquid crystal light modulator 10 is driven by shorting the upper electrode 41 and the common electrode 32, the potential difference between the electrodes 31 and 32 is the potential difference between the electrodes 31 and 41, that is, the liquid crystal light modulator 10 is the same as the applied voltage. Alternatively, the electrode interlayer insulating film 52 may be made of a high dielectric constant (High-κ) insulating material that is applied to the gate oxide film of a fine MOSFET (metal oxide semiconductor field effect transistor) or the like. HfSiO ₄ , ZrSiO ₄ , HfO ₂ , ZrO ₂ , cubic crystal phase HfO ₂ (see Japanese Patent No. 5652926), etc., can be cited as high dielectric constant insulating materials. When the dielectric constant of the electrode interlayer insulating film 52 is high, the voltage applied to the liquid crystal layer 20 above the opening 32a is prevented from decreasing with respect to the voltage applied to the liquid crystal optical modulator 10 . As a result, the voltage applied to the liquid crystal optical modulator 10 can be reduced, and the potential difference between the electrodes 31 and 32 is accordingly reduced, so that the thickness of the electrode interlayer insulating film 52 can be reduced to some extent.

(Transparent substrate)
The transparent substrate 61 is a base for forming the upper electrode 41 and the alignment film 21 , and the transparent substrate 62 is a base for forming the lower electrode 31 , the inter-electrode insulating film 52 , the common electrode 32 and the alignment film 22 . be. Furthermore, the transparent substrates 61 and 62 together are a base for supporting the liquid crystal layer 20 . The transparent substrates 61 and 62 are made of a known transparent substrate material so as to transmit light, and the transparent substrate 61 is resistant to the film forming conditions (temperature, atmosphere, etc.) of the upper electrode 41 and the alignment film 21. , and the transparent substrate 62 is made of a material that is resistant to the film formation and processing conditions of the lower electrode 31, the common electrode 32, and the like. Specific examples include SiO ₂ (silicon oxide, glass), sapphire, polycarbonate (PC), and the like. Alternatively, the transparent substrates 61 and 62 may be flexible plastic substrates such as transparent polyimide films so that the liquid crystal optical modulator 10 may be flexible depending on its application. In this case, the electrodes 31, 32, and 41 are preferably made of flexible nanocarbon materials or conductive polymers among the transparent electrode materials.

(Manufacturing method of liquid crystal optical modulator)
The liquid crystal optical modulator according to this embodiment can be manufactured according to a known method for manufacturing a transmissive liquid crystal optical modulator. That is, electrodes 41, 31, 32, etc. are formed on transparent substrates 61, 62, respectively, and alignment films 21, 22 are further formed. 62 are superimposed and the liquid crystal material is enclosed between them. Since the liquid crystal optical modulator 10 only needs to be patterned on one layer of the common electrode 32, it can be easily manufactured and is suitable as an experimental device.

In the liquid crystal optical modulator 10 according to the present embodiment, as shown in FIG. 7, the electrode interlayer insulating film 52 may be formed also in the opening 32a so that the height position of the surface is aligned with the common electrode 32. . With such a configuration, the surface of the alignment film 22 can be made flat especially when the alignment film 22 is formed of an inorganic film. does not occur. The portion (embedded insulating layer 5a) in the opening 32a of the electrode interlayer insulating film 52 does not have to be made of the same insulating material as the portion between the common electrode 32 and the lower electrode 31, and the material of the electrode interlayer insulating film 52 is mentioned above. selected from insulating materials; The buried insulating layer 5a preferably has a high dielectric constant, especially when the common electrode 32 is thick. Such a liquid crystal light modulator 10 can be manufactured, for example, by forming a film of the material of the common electrode 32 on the inter-electrode insulating film 52, forming a mask having a region for forming the opening 32a thereon, and etching the film. After the opening 32a is formed, the material of the buried insulating layer 5a is deposited from above, and the mask is removed. Alternatively, in the liquid crystal optical modulator 10, a mask is formed on the inter-electrode insulating film 52 to cover the region where the opening 32a is to be formed, and the inter-electrode insulating film 52 is etched by the thickness of the common electrode 32. It can also be manufactured by forming a film of the material of the common electrode 32 and removing the mask.

The liquid crystal optical modulator 10 according to the present embodiment may include an electrode interlayer insulating film 52A having openings aligned with the openings 32a of the common electrodes 32, as shown in FIG. 52 A of electrode interlayer insulation films can be made into the same material and thickness as the electrode interlayer insulation film 52. As shown in FIG. However, in order to reduce the step on the surface of the alignment film 22 at the edge of the opening 32a, the thickness of the electrode interlayer insulating film 52A is preferably reduced similarly to the common electrode 32. FIG. The opening of the electrode interlayer insulating film 52A has the same or smaller planar shape than the opening 32a. Such a liquid crystal light modulator 10 can be manufactured by etching the common electrode 32 from above a mask having a region for forming the opening 32a, and then continuously etching the electrode interlayer insulating film 52A. Alternatively, in the liquid crystal light modulator 10, a mask is formed on the lower electrode 31 to cover the region where the opening 32a is to be formed. can also be produced by removing In addition, a buried insulating layer 5a (see FIG. 7) may be provided in the opening 32a of the common electrode 32 and the opening of the inter-electrode insulating film 52A to planarize the surface on which the alignment film 22 is formed.

(Liquid crystal display device)
The liquid crystal optical modulator 10 according to the first embodiment of the present invention is used in a liquid crystal display device like a general transmissive liquid crystal optical modulator. As shown in FIG. 9, the liquid crystal display device 100 according to the embodiment of the present invention includes a liquid crystal optical modulator 10 and polarizing plates (polarizers) 71 and 72 arranged above and below the liquid crystal optical modulator 10, respectively. Prepare. Furthermore, since the liquid crystal optical modulator 10 is of the TN system, the liquid crystal display device 100 preferably includes retardation plates 73 and 74 between the liquid crystal optical modulator 10 and the polarizing plates 71 and 72, respectively. When displaying a full-color image, the liquid crystal display device 100 also has a color filter array 75 in which color filters of red (R), green (G), and blue (B) are arranged in stripes or mosaics. is provided on the light exit side of the liquid crystal optical modulator 10 (see FIG. 10). The liquid crystal display device 100 may further include a grid-shaped black matrix along the center between pixels together with the color filter array 75 . Note that the color filter array 75 does not have to switch colors for each pixel of the liquid crystal optical modulator 10. For example, 2×2 ₌ 4 pixels constitute one pixel in the liquid crystal display device 100 (pixel length is 2 la ). may be Such a liquid crystal display device 100 has 5 gradations of 0% (black), 25%, 50%, 75%, and 100% (white) by the light and dark pattern of each of the four pixels of the liquid crystal optical modulator 10. can be displayed. The liquid crystal display device 100 can be irradiated with light from one of the upper and lower sides and can display an image on the other side. Here, it is assumed that light is irradiated from above and an image is displayed downward. . The light that irradiates the liquid crystal display device 100 may be external light, indoor light, or a planar light source that incorporates a light-emitting element such as a light-emitting diode (LED), similar to the backlight of a general liquid crystal display, depending on the application. selected.

The polarizing plate (polarizer) 71 on the upper side, ie, the light incident side, converts the non-polarized light L _uP incident from the outside into light of one polarization component (linearly polarized light in one direction). In the liquid crystal display device 100, the polarizing plate 71 is arranged with the transmission axis in the horizontal direction (90°) in FIG. . A polarizing plate (analyzer) 72 on the lower side, that is, on the light emitting side, transmits polarized light in a predetermined direction out of the light emitted from the liquid crystal optical modulator 10 and displays it. In the liquid crystal display device 100, the polarizing plate 72 has its transmission axis arranged in the same direction as the polarizing plate 71, that is, a parallel Nicol arrangement. The polarizer 71 on the light incident side may be a polarization conversion element that emits all of the incident non-polarized light L _uP as linearly polarized light in one direction (90° vibration direction). A polarization conversion element is composed of a polarization separation film and a half-wave plate.

The retardation plates 73 and 74 are provided to compensate for the phase difference of light due to the liquid crystal layer 20, and may be a λ/2 retardation plate (1/2 wavelength plate) or a λ/4 retardation plate (1/4 wavelength plate). ) applies. Due to the optical anisotropy of the liquid crystal molecules, the liquid crystal changes its refractive index depending on the orientation of the liquid crystal molecules. Specifically, in the liquid crystal layer 20, the phase difference δ due to the polarized component is 0 when the liquid crystal molecules 2 stand vertically as shown in the left side of FIG. 5 As shown on the right side, a phase difference occurs when it is horizontally tilted. In this embodiment, as described above, the maximum phase difference δ of the liquid crystal layer 20 is π (=λ/2) when the liquid crystal molecules 2 are horizontal. In this embodiment, dark display is performed in a state in which a phase difference is generated in the liquid crystal layer 20. Therefore, the phase difference changes depending on the angle of the liquid crystal molecules 2, and light may leak when viewed obliquely. Therefore, it is preferable to compensate for the phase difference caused by the liquid crystal layer 20 with the retardation plates 73 and 74 . Here, the retardation plates 73 and 74 are both λ/4 retardation plates, and are arranged with their slow axes at 45° and 135° with respect to the transmission axis of the polarizing plate 71, respectively.

(Operation of Liquid Crystal Optical Modulator)
The operation of the liquid crystal optical modulator according to the first embodiment will be described with reference to FIG. 9 and, if necessary, FIG. When the driving method is the TN method, the VA method, or the like, the liquid crystal exhibits the same behavior regardless of whether the direction of the electric field is up or down, and generally deteriorates if the voltage is continuously applied with a constant polarity, so an AC voltage is applied. preferably. As shown in FIG. 9, the liquid crystal optical modulator 10 has an AC power source 91 connected between the electrodes 31 and 41, the upper electrode 41 and the common electrode 32 are shorted to have the same potential, and the AC power source 91 is The terminal on the upper electrode 41 side is connected to GND (0 V). Then, voltage is applied to the liquid crystal layer 20 from the upper and lower electrodes 31 and 41, so that a vertical electric field (represented by hatched upward arrows in the figure) is generated. However, since the common electrode 32 arranged near the liquid crystal layer 20 with respect to the lower electrode 31 has the same potential as the upper electrode 41, no electric field is generated in the region sandwiched between the common electrode 32 and the upper electrode 41. An electric field is generated only in the region where the common electrode 32 is not provided (above the opening 32a). Since the liquid crystal layer 20 is of the TN system, the liquid crystal molecules 2 stand up on the openings 32a where the electric field is generated.

Here, in the liquid crystal optical modulator 10, the voltage applied to the liquid crystal layer 20 above the opening 32a is the voltage of the AC power source 91 because the liquid crystal layer 20 and the lower electrode 31 are separated by the electrode interlayer insulating film 52. less than the voltage (potential difference between the electrodes 31-41). Hereinafter, the potential of the upper electrode 41 is V0 (=0 V), the potential of the lower electrode 31 is V1, the potential of the common electrode 32 is V2 (=V0=0 V), and the potential of the lower surface of the liquid crystal layer 20 above the opening 32a is V5. Describe and briefly describe. Here, the potential drop due to the alignment films 21 and 22 is neglected because the thickness thereof is sufficiently small with respect to the liquid crystal layer 20 . Therefore, the potential on the upper surface of the liquid crystal layer 20 is set to the same potential V0 as that of the upper electrode 41 . Similarly, the potential on the lower surface of the liquid crystal layer 20 above the common electrode 32 (outside the opening 32a) is set to the same potential V2 (=0 V) as the common electrode 32. FIG. When a voltage V _DD (V1=V _DD ) is applied between the electrodes 31-41, the potential difference ΔV (=|V1-V5|) between V1-V5 is expressed by the following equation (1): , is proportional to the distance d between the liquid crystal layer 20 and the lower electrode 31 , that is, the thickness of the inter-electrode insulating film 52 . E _D is an electric field generated in the electrode interlayer insulating film 52 and is inversely proportional to the dielectric constant of the electrode interlayer insulating film 52 . Therefore, the inter-electrode insulating film 52 is applied to the liquid crystal layer 20 so that the voltage (maximum drive voltage) V _LC is applied to the liquid crystal layer 20 so that the liquid crystal molecules 2 stand upright and the phase difference δ of the liquid crystal layer 20 becomes 0 (V5≧V _LC ). The voltage V _DD (≧V _LC +ΔV) of the AC power supply 91 is set according to the dielectric constant and thickness of .
ΔV=E _D d (1)

In this way, the electrode on the lower side of the liquid crystal layer 20 is provided in two layers with the electrode interlayer insulating film 52, which is a dielectric, interposed therebetween, and the opening 32a is formed in the common electrode 32 on the side closer to the liquid crystal layer 20. By locally generating a vertical electric field in a two-dimensional pattern corresponding to the arrangement of the openings 32a, the liquid crystal layer 20 (liquid crystal molecules 2) can be placed in one of two operating states for each region. .

The liquid crystal layer 20 may be surface stabilized ferroelectric liquid crystal (SSFLC). Since ferroelectric liquid crystals have spontaneous polarization, such a liquid crystal light modulator 10 uses, for example, two DC currents to generate electric fields opposite to each other on the common electrode 32 and on the apertures 32a of the liquid crystal layer 20. Power is connected. The first power supply has a positive electrode connected to the lower electrode 31 and a negative electrode connected to GND and the upper electrode 41 respectively, and a second power supply has a positive electrode connected to GND and the upper electrode 41 and a negative electrode connected to the common electrode 32 . If the voltage applied to the liquid crystal layer 20 that generates an upward electric field with the required strength is expressed as V _LC 1 and the applied voltage that generates a downward electric field is expressed as V _LC 2, the voltages V of the first and second power supplies are respectively. _DD 1 and V _DD 2 are set to V _DD 1≧V _LC 1+ΔV and V _DD 2≧V _LC 2. Since it is preferable that linearly polarized light is incident on such a liquid crystal optical modulator 10, the liquid crystal display device 100 is configured without the retardation plates 73 and 74. FIG.

(Operation of liquid crystal display device)
The operation of the liquid crystal display device according to this embodiment will be described. The unpolarized L _uP incident on the liquid crystal display device 100 from above is converted into light L in regular vibration directions before entering the liquid crystal optical modulator 10 . First, the polarizing plate 71 converts the linearly polarized light L in the 90° direction (with a double-headed arrow indicating the polarization direction), and the retardation plate 73 converts this linearly polarized light into left-handed circularly polarized light (left-handed circularly polarized light). be. The left circularly polarized light L passes through the transparent substrate 61 , the upper electrode 41 and the like, and enters the liquid crystal layer 20 . The light L incident on the common electrode 32 (outside the opening 32a) in the no electric field state is modulated from left-handed circularly polarized light to right-handed circularly polarized light when passing through the liquid crystal layer 20 because the phase difference δ in this region is π. (See FIG. 6), the light is sequentially transmitted from the common electrode 32 to the transparent substrate 62 and emitted downward from the liquid crystal light modulator 10 . The right-handed circularly polarized light L emitted from the liquid crystal optical modulator 10 is converted by the retardation plate 74 into linearly polarized light in the direction of 0° (perpendicular to the plane of the paper in FIG. 9). 90) is completely shielded by the polarizing plate 72 . On the other hand, since the light L incident on the aperture 32a where the electric field is generated has a phase difference δ of 0 in this region, it is transmitted as left circularly polarized light and emitted downward from the liquid crystal light modulator 10. The light is converted into linearly polarized light in the direction of 90° by the plate 74 , transmitted through the polarizing plate 72 , and emitted from the liquid crystal display device 100 .

In this manner, the liquid crystal display device 100 including the liquid crystal optical modulator 10 allows light to be incident on the entire surface and to be extracted only from the area where the opening 32a of the common electrode 32 is formed on the opposite side. Therefore, a desired image can be displayed by the pattern of the openings 32a formed in the common electrode 32. FIG.

The liquid crystal display device 100 can also emit light from the entire surface. For this reason, the common electrode 32 and the upper electrode 41 are arranged so that a voltage equal to or higher than the maximum driving voltage V _LC is applied to the entire liquid crystal layer 20, that is, both over the opening 32a and over the common electrode 32 (outside the opening 32a). Break the short. Then, as an example, the common electrode 32 is short-circuited with the lower electrode 31 and connected to the terminal on the non-GND side of the AC power supply 91 . At this time, the voltage of the AC power supply 91 is set so that the potential difference between the potential V5 on the lower surface of the liquid crystal layer 20 above the opening 32a and the potential V0 (=0 V) of the upper electrode 41 is greater than or equal to the maximum drive voltage _VLC . Alternatively, as shown in FIG. 9, by switching with a switch 94, the connections with the terminals of the AC power supply 91 are also exchanged, the lower electrode 31 and the common electrode 32 are connected to GND (0 V), and the upper electrode 41 is connected to the AC power supply. 91 may be configured to be connected to the terminal on the non-GND side.

In the liquid crystal display device 100, the slow axis of the retardation plate 74 is arranged at 45°, which is the same as that of the retardation plate 73, and the transmission axis of the polarizing plate 72 is arranged at 0° (crossed Nicol arrangement with respect to the polarizing plate 71). ) to extract linearly polarized light in the direction of 0° from the region in which the opening 32a is formed. Further, when the liquid crystal layer 20 of the liquid crystal optical modulator 10 is of the VA type, the phase difference δ is 0 in the absence of an electric field (see the modified example shown in FIG. 12 described later). Either the slow axis of the retardation plate 74 or the transmission axis of the polarizing plate 72 is changed. Depending on the application, the liquid crystal display device 100 may have a configuration in which the directions of the polarizing plates 71 and 72 and the retardation plates 73 and 74 are changed to reverse black and white so that light is extracted from the outside of the opening 32a of the common electrode 32. FIG.

The liquid crystal display device 100 according to the present embodiment can display a two-dimensional image (see FIG. 4) of a fixed pattern by arranging the openings 32a in the common electrode 32 on the surface (polarizing plate 72) on the light output side. can. Further, by providing a color filter array 75 (see FIG. 10) on the light exit side of the liquid crystal optical modulator 10, a full-color image can be displayed. As the light source, as described above, external light, indoor light, or a general lighting device can be used. Therefore, the liquid crystal display device 100 can be attached to a windowpane of a building, for example, and can display an image on the indoor side with the outdoor side as the light incident side. When the AC power source 91 (see FIG. 9) is turned off, the entire surface is displayed in black because light does not pass through the entire surface. On the other hand, in the liquid crystal display device 100, by switching the connection of the AC power supply 91 as described above, the entire surface of the liquid crystal display device 100 can transmit light. Alternatively, the liquid crystal display device 100 can be attached to, for example, a glass plate in front of a show window and installed to display an image to the outside by lighting inside the show window. By switching the connection of the AC power supply 91, the exhibit in the show window can be made visible from the outside without displaying the image. In addition, the liquid crystal display device 100 has flexibility by applying a flexible substrate to the transparent substrates 61 and 62 as described above, and can be attached and installed on a curved surface. Thus, the liquid crystal display device 100 can be widely used for posters, advertisements, billboards, and the like.

(Stereoscopic image display device)
The liquid crystal optical modulator according to the present invention can be applied to an integral stereoscopic image display device (hereinafter referred to as a stereoscopic image display device). As shown in FIG. 10, the stereoscopic image display device 200 according to the embodiment of the present invention further includes a light source device 80, a color filter array 75, a lens array 85, and an AC power supply 91 (see FIG. 9) in addition to the liquid crystal display device 100. Prepare. The AC power supply 91 is as described for the liquid crystal display device 100 . The light source device 80 includes a light-emitting element such as an LED, a light guide plate, and the like in the same manner as a general backlight, and displays white light as a parallel light beam having a diameter that encompasses the entire light incident surface of the liquid crystal light modulator 10 for liquid crystal display. The device 100 is illuminated. The light emitting elements of the light source device 80 may be white LEDs or the like, but in order to improve color reproducibility, it is preferable to include monochromatic light emitting elements of R, G, and B respectively. Further, the stereoscopic image display device 200 may have a configuration in which the light source device 80 irradiates linearly polarized light instead of the liquid crystal display device 100 including the polarizing plate 71 on the light incident side. , a polarizer or a polarization conversion element. The color filter array 75 has R, G, and B color filters arranged in stripes or mosaics in accordance with the pixels of the liquid crystal light modulator 10 , and is arranged on the light exit side of the liquid crystal light modulator 10 . be. The lens array 85 is an optical element array for spatially sampling a group of elemental images, is formed by two-dimensionally arranging elemental lenses, and is arranged on the light exit side of the liquid crystal display device 100 . In the stereoscopic image display device 200, the narrower the arrangement pitch of the element lenses of the lens array 85, the higher the resolution. Become. Therefore, it is preferable that the pixels of the liquid crystal optical modulator 10 are high density and numerous. In addition, the smaller the focal length f of the element lenses of the lens array 85 relative to the diameter Φ, that is, the smaller the F number, the wider the viewing zone angle Ψ of the stereoscopic image as expressed by the following equation (2). .
Ψ=2tan ^-1 (Φ/2f) (2)

As described above, the integral stereoscopic image display device 200 including the liquid crystal display device 100 according to the present embodiment can display a full-color stereoscopic image with a simple configuration. Further, the stereoscopic image display device 200 can be switched to a white lamp by emitting light from the entire surface of the liquid crystal display device 100 as described above.

(Holography device)
The liquid crystal optical modulator according to the present invention can also be used in a holographic stereoscopic image display device (hereinafter referred to as a holographic device). As shown in FIG. 11, the holography device 200B according to the embodiment of the present invention includes a liquid crystal optical modulator 10B, a light source device 8 that irradiates linearly polarized light, an AC power supply 91, and, if necessary, a magnifying optical system 86. . The holography device 200B forms a monochromatic stereoscopic image at a predetermined distance from the light exit surface (lower surface) of the liquid crystal layer 20 of the liquid crystal optical modulator 10B as a hologram surface.

The liquid crystal optical modulator 10B is a spatial optical phase modulator, and modulates the phase of light in a predetermined polarization direction, ie, incident light L, for each region (pixel). Therefore, the liquid crystal layer 20 makes the slow axis the polarization direction of the light L by the upper and lower alignment films 21 and 22 (not shown in FIG. 11). The liquid crystal layer 20 has a thickness (cell thickness) at which the amount of change in the phase of transmitted light becomes π in the no-electric-field state in the case of the TN method and in the state of applying the maximum driving voltage V _LC in the case of the VA method. preferably. The liquid crystal light modulator 10B also includes a common electrode 32B with openings 32a arranged to form a computer-generated hologram (CGH) (see Non-Patent Document 2) pattern. The common electrode 32B is not particularly limited in the pattern of the openings 32a or the shape of each individual planar view, and may be separated into two or more portions by the openings 32a, for example. is formed in such a way that

The light source device 8 includes a light source 81 , an optical system 84 and a polarizer 71 . The light source 81 is a monochromatic light source, and it is preferable to apply a laser light source such as a semiconductor laser (LD) or a gas laser so as to irradiate light with the same phase (coherent light). The optical system 84 is a beam expander or the like, and converts the light emitted from the light source 81 into a parallel beam having a diameter that encompasses the entire light incident surface of the liquid crystal optical modulator 10B. As described for the liquid crystal display device 100, the polarizer 71 converts incident non-polarized light L _uP into linearly polarized light L in one direction, and may be a polarization conversion element. The light source device 8 may apply a polarized laser to the light source 81 instead of including the polarizer 71 . The magnifying optical system 86 is composed of one or more lenses, and is arranged on the light exit side of the liquid crystal optical modulator 10B in order to output a stereoscopic image in a desired size.

When the coherent linearly polarized light L is incident on the liquid crystal optical modulator 10B, the light transmitted through the liquid crystal layer 20 in which an electric field is generated on the opening 32a of the common electrode 32B, or the electric field-free state on the common electrode 32B (outside the opening 32a). One of the phases of the light transmitted through the liquid crystal layer 20 changes, and as a result, two types of light with different phases are emitted. Then, a stereoscopic image is formed by interference of light beams of the same phase. Further, if the liquid crystal layer 20 has a cell thickness such that the phases are different from each other by π, the light transmitted through the common electrode 32B and the light transmitted through the opening 32a can be offset by interference to produce a dark display. .

Here, the viewing zone angle Ψ in the holography device depends on the pixel length p (λ: wavelength of light), as expressed by the following equation (3). That is, in the holography device 200B, the finer the pattern of the openings 32a of the common electrode 32B, the wider the viewing angle Ψ can be, depending on the pitch of the openings 32a of the common electrode 32B. For example, for blue light (λ=408 nm) in the short wavelength region of visible light, p≤0.8 μm in order to satisfy Ψ≧30°.
Ψ=2 sin ⁻¹ (λ/2p) (3)

Similar to the liquid crystal display device 100 (see FIG. 9), the holography device according to the present embodiment further includes retardation plates 73 and 74 and a polarizing plate 72 above and below the liquid crystal optical modulator 10B, and the liquid crystal above the opening 32a. Only the light transmitted through the layer 20 may be emitted by the polarizer 72 to interfere with each other. Also, an LED or the like may be applied to the light source 81 of the light source device 8 .

By providing three holography devices 200B for outputting images of respective colors of R, G, and B, and further providing a color synthesizing optical system, a three-plate type color holography device can be obtained (see FIG. 6 in Non-Patent Document 1). reference). In each holography device 200B, the light source device 8 emits one of red light, green light, and blue light, and the liquid crystal optical modulator 10B emits light in a pattern matching the color image of the light emitted by the light source device 8. It has a formed common electrode 32B. Note that the three holography devices 200B may share the AC power supply 91 . The color combining optics are a dichroic prism or two dichroic mirrors. The three holography devices 200B are arranged so that the positions where the images of the respective colors output from them are formed are aligned. Alternatively, by stacking three liquid crystal light modulators 10B each having a common electrode 32B formed in a pattern corresponding to each color image of R, G, and B, and providing a light source device for alternately irradiating light of each color, It can be a time division color holography device. For example, when the light source device emits red light, the liquid crystal optical modulator 10B for red is driven. When the other two liquid crystal optical modulators 10B are turned off, the phase difference .delta. of the entire surface becomes 0 or .pi., and the total becomes 0 or 2.pi., which does not affect the modulation of the red light.

Thus, the holography device 200B including the liquid crystal optical modulator 10B can display a stereoscopic image with a simple configuration. Also, by providing three holography devices 200B for displaying R, G, and B images, a full-color stereoscopic image can be displayed.

(Projection type display device)
The liquid crystal display device 100 according to the present embodiment includes a light source device 80A (see FIG. 13) for irradiating light on one side thereof, and a projection lens (enlarging optical system) 86A (see FIG. 13) on the other side. By connecting the AC power supply 91 to the liquid crystal optical modulator 10, a projection type display device (projector) that projects an image onto a screen can be formed. As the light source device 80A and the projection lens 86A, those used in known liquid crystal projectors can be applied. In order to display a full-color image, the liquid crystal display device 100 further includes a color filter array 75 (see FIG. 10), and three light sources of R, G, and B are used as light sources so that the light source device 80A emits white light. Equipped with colored lasers or LEDs and a color synthesizing optical system, or a mercury lamp or the like. Alternatively, like the three-panel type color holography device, three liquid crystal display devices 100 in which the common electrode 32 is formed in a pattern corresponding to each color image of R, G, and B, and each liquid crystal display device 100 A monochromatic light source device for irradiating light of each color may be provided in the unit, and the emitted light of each color may be synthesized by a color synthesizing optical system and projected onto the screen via the projection lens 86A.

(Modification)
Although the liquid crystal optical modulators according to the above embodiments are transmissive spatial light modulators, they can also be reflective spatial light modulators. A liquid crystal optical modulator according to a modification of the first embodiment of the present invention and a liquid crystal display device including the same will be described below with reference to FIG. Elements that are the same as those of the first embodiment (see FIGS. 1 to 11) are denoted by the same reference numerals, and description thereof is omitted.

A liquid crystal optical modulator 10A according to a modification of the first embodiment of the present invention includes a liquid crystal layer 20A, an upper electrode 41 and a lower electrode 31A sandwiching the liquid crystal layer 20A from above and below, and provided between the lower electrode 31A and the liquid crystal layer 20A. and a common electrode 32, and an inter-electrode insulating film 52 for insulating the common electrode 32 from the lower electrode 31A. The liquid crystal optical modulator 10A further includes alignment films 21 and 22 respectively in contact with the upper and lower surfaces of the liquid crystal layer 20A, a transparent substrate 61 above the upper electrode 41, and a substrate 62A below the lower electrode 31A. The liquid crystal light modulator 10A is a reflective spatial light modulator that reflects light incident on the entire surface from above and emits it upward, changing the polarization direction of the light in a predetermined partial region. .

For the liquid crystal layer 20A, the same liquid crystal material as that for the liquid crystal layer 20 of the above embodiment can be selected. Here, the liquid crystal layer 20A is of the VA system, and the liquid crystal molecules 2 stand upright and the phase difference δ is 0 in the absence of an electric field. The vertical electric field tilts the liquid crystal molecules 2 with an inclination corresponding to the strength thereof, and when the maximum drive voltage V _LC is applied, the liquid crystal molecules 2 assume a horizontal orientation along the film surface direction, and the phase difference δ becomes maximum. In the liquid crystal light modulator 10A, which is a reflective spatial light modulator, the light L is emitted by reciprocating in the liquid crystal layer 20A. It is preferable to design Therefore, the cell thickness is smaller than that of the transmissive liquid crystal optical modulator, and the response speed can be increased.

The liquid crystal light modulator 10A is a reflective spatial light modulator, and the lower electrode 31A does not need to transmit light. It is formed of a general metal electrode material such as an alloy, and may be laminated with two or more of the above metals or alloys. It is preferable that the lower electrode 31A is made of a material having a high light reflectance and a sufficient thickness so that the light incident from above has a high reflectance. Alternatively, the liquid crystal optical modulator 10A has a lower electrode 31 that transmits light as in the above embodiment, and the substrate 62A thereunder or a reflective film (not shown) provided therebelow reflects the light L. It may be configured to allow Since the substrate 62A does not need to transmit light, a Si substrate, a metal plate, a plastic plate, or the like can be applied in addition to the transparent substrate 62 of the above embodiment. Also, as in the above-described embodiment, flexible plastic substrates are applied to the substrates 61 and 62A so that the liquid crystal optical modulator 10A may be flexible depending on its application. In this modified example, the lower electrode 31 and the transparent substrate 62 that transmit light are provided on the lower side of the liquid crystal layer 20A, and light is incident from below, and the upper electrode 41 or the substrate (transparent substrate 61) thereon is exposed. It is good also as a structure which reflects light by . In other words, the common electrode 32 and the inter-electrode insulating film 52 may be arranged on the light incident side of the liquid crystal layer 20A.

In the operation of the liquid crystal light modulator 10A according to this modified example, the generation of an electric field by voltage application from the AC power supply 91 is the same as that of the liquid crystal light modulator 10 (see FIG. 9) according to the above embodiment. In this modified example, since the liquid crystal layer 20A is of the VA system, the liquid crystal molecules 2 stand up outside the openings 32a (on the common electrode 32) in the no electric field state, as shown in FIG.

A liquid crystal light modulator 10A according to a modification of the first embodiment of the present invention is used in a liquid crystal display device like a general reflective liquid crystal light modulator. As shown in FIG. 12, the liquid crystal display device 100A according to the modification of the embodiment of the present invention includes a liquid crystal optical modulator 10A and a polarizing plate disposed on the light input/output side (upper side) of the liquid crystal optical modulator 10A. A (polarizer) 72 is preferably provided, and a retardation plate 73 is preferably provided between the liquid crystal optical modulator 10A and the polarizer 72 . Further, when displaying a full-color image, the liquid crystal display device 100A includes a color filter array 75 (see FIG. 10) on the light input/output side of the liquid crystal optical modulator 10A.

(Operation of liquid crystal display device)
The operation of the liquid crystal display device according to this modification will be described. As in the liquid crystal display device 100 (see FIG. 9) according to the above embodiment, the non-polarized L _uP incident on the liquid crystal display device 100A from above is converted into left-handed circularly polarized light by the polarizing plate 72 and the retardation plate 73. It passes through the transparent substrate 61, the upper electrode 41, etc., and enters the liquid crystal layer 20A. The light L incident on the common electrode 32 (outside the opening 32a) in the no electric field state has a phase difference δ of 0 in this region, so the light L is transmitted as left circularly polarized light and reaches the lower electrode 31A. The left-handed circularly polarized light changes to right-handed circularly polarized light when reflected by the lower electrode 31A, passes through the liquid crystal layer 20A again from below, passes through the upper electrode 41 and the transparent substrate 61, and enters the retardation plate 73. . Since the retardation plate 73 converts the right-handed circularly polarized light into linearly polarized light in the direction of 0°, the linearly polarized light L is blocked by the polarizing plate 72 and is not emitted. On the other hand, the light L incident on the opening 32a where the electric field is generated changes from left-handed circularly polarized light to linearly polarized light in the 0° direction when passing through the liquid crystal layer 20A because the phase difference δ in this region is π/2. (see FIG. 6) to reach the lower electrode 31 . The linearly polarized light does not change its state when it is reflected, so the 0° linearly polarized light L re-enters the liquid crystal layer 20A from below. Then, the liquid crystal layer 20A returns the linearly polarized light in the 0° direction to left-handed circularly polarized light, and the retardation plate 73 converts it into linearly polarized light in the 90° direction. The light is emitted upward from the liquid crystal display device 100A.

In this manner, the liquid crystal display device 100A having the liquid crystal light modulator 10A receives natural light such as external light from the entire surface, and the opening 32a of the common electrode 32 is formed on the same side surface (polarizing plate 72). Since light can be extracted only from the region, a desired image can be displayed by the pattern of the openings 32a, similarly to the liquid crystal display device 100 having the transmissive liquid crystal optical modulator 10. FIG.

Like the liquid crystal display device 100, the liquid crystal display device 100A can switch the connection between the electrodes 31, 41, and 32 and the AC power supply 91 to emit light from the entire surface. As described in the above embodiment, the connection of the common electrode 32 is switched to break the short circuit with the upper electrode 41 and short circuit with the lower electrode 31 . Alternatively, an AC power supply having a voltage lower than that of the AC power supply 91 (V _LC or more and less than _VDD ) may be connected to the common electrode 32 in consideration of the potential difference ΔV between V1 and V5. As such an AC power supply, a power supply device 92 is provided as shown in FIG. The power supply device 92 receives a voltage from the AC power supply 91 and outputs a voltage smaller than this voltage in synchronization with the AC power supply 91 .

In the liquid crystal display device 100A, one polarizing plate 72 serves both as a polarizer and an analyzer. It must be in the same polarization state as the light incident on the optical modulator 10A. When the TN system is applied, the transmissive liquid crystal optical modulator 10 is provided with electrodes 31 and 41 and transparent substrates 61 and 62 that transmit light vertically, and the liquid crystal layer 20 has a phase difference δ is designed to have a cell thickness of π/2. A retardation plate 74 is arranged below the liquid crystal optical modulator 10 (see FIG. 9), and a reflector is arranged below it.

(Projection type display device)
A liquid crystal display device including the liquid crystal optical modulator 10A according to this modified example can be used for a projection type display device (projector) as in the above embodiment. As shown in FIG. 13, such a liquid crystal display device 100C includes a polarizing beam splitter 76 on the light input/output side of the liquid crystal light modulator 10A. It is configured to have a phase difference of π with the light emitted from the application region). The projection-type display device 200C includes a liquid crystal display device 100C, a light source device 80A and a projection lens 86A arranged on the side and above the polarizing beam splitter 76, respectively, and an AC power source 91 connected to the liquid crystal optical modulator 10A. . In order to display a full-color image, the liquid crystal display device 100C further includes a color filter array 75 and the light source device 80A emits white light. The light source device 80A irradiates the polarizing beam splitter 76 with unpolarized L _uP from the side, and the S-polarized light (linearly polarized light L in the direction perpendicular to the paper surface) reflected by the polarizing beam splitter 76 reaches the retardation plate on the liquid crystal optical modulator 10A. 73. Of the light modulated by the liquid crystal optical modulator 10A and emitted from the retardation plate 73, the P-polarized light passes through the polarization beam splitter 76 and is emitted via the projection lens 86A. Alternatively, as described in the above embodiment, a three-panel projection display device may be used.

The liquid crystal light modulator 10A according to this modification includes a common electrode 32B formed with a pattern of a computer-generated hologram in the same manner as the liquid crystal light modulator 10B (see FIG. 11) according to the above-described embodiment. can be used. In the holography device according to the modification having such a reflective liquid crystal light modulator 10A, the incident light is incident on the liquid crystal light modulator 10A at a slight angle so that the optical paths of the incident light and the emitted light do not match. The light source device 8 is arranged as shown in FIG. Alternatively, the holography device is equipped with a half mirror (non-polarizing beam splitter) inclined at 45° on the light input/output side (upper side) of the liquid crystal optical modulator 10A, and the incident angle from the light source device 8 placed thereon is The light L is incident at 0°, and the light emitted from the liquid crystal optical modulator 10A is reflected sideways by the half mirror. Alternatively, the holography device according to this modified example has a retardation plate 73 on the liquid crystal optical modulator 10A, and a polarizing beam splitter instead of the half mirror, similarly to the liquid crystal display device 100C (see FIG. 13). 76 may be provided to emit only the light that has passed through the liquid crystal layer 20A above the opening 32a and cause interference between these lights. In order to display a full-color stereoscopic image, three holography devices for outputting R, G, and B images and a color synthesizing optical system are provided as in the above-described embodiment. Construct a color holography device.

As described above, according to the liquid crystal light modulators according to the first embodiment and the modified example of the present invention, it is possible to obtain a liquid crystal display device that has a simple configuration, fine pixels, and displays a desired image. Further, according to the integral type stereoscopic image display device using such a liquid crystal display device, it is possible to increase the parallax information and the resolution. Further, according to a holography device using such a liquid crystal display device, a stereoscopic image can be obtained with a wide viewing angle.

[Second embodiment]
Although the liquid crystal optical modulators according to the first embodiment and its modified example perform binary display of black and white, it is also possible to perform gradation display including halftones without increasing the number of signals. A liquid crystal optical modulator according to the second embodiment will be described below. Elements that are the same as those of the first embodiment (see FIGS. 1 to 13) are denoted by the same reference numerals, and descriptions thereof are omitted.

As shown in FIG. 14, in the liquid crystal optical modulator 10E according to the second embodiment of the present invention, in the region where the openings 32a of at least a part of the common electrode 32 are formed, the electrode interlayer insulating film 52B is A hole of a predetermined depth is formed in each of the holes to have different thicknesses. In FIG. 14, the opening 32a on the left side has no hole, and the opening 32a on the right side has a hole with half the thickness.

The electrode interlayer insulating film 52B may have a minimum thickness of 0, that is, may have through holes. On the other hand, the inter-electrode insulating film 52B can have a maximum thickness and no holes, or it can be embedded up to the inside of the opening 32a (see FIG. 7). The liquid crystal optical modulator 10E can display one more gradation than the number of steps of the thickness of the electrode interlayer insulating film 52B (including a thickness of 0). Here, the voltage V _DD applied between the electrodes 31 and 41 is (potential V0 of the upper electrode 41=0 V), and the potential V7 on the lower surface of the liquid crystal layer 20 in the region of the maximum thickness of the electrode interlayer insulating film 52B is the predetermined value described later. (minimum driving voltage V _LC ') (see FIG. 15). When such a voltage V _DD is applied between the electrodes 31 and 41, the potential at the lower surface of the liquid crystal layer 20 is a desired value (greater than V _LC ′ and less than or equal to V _LC ) for each opening 32a. A small hole is formed in the electrode interlayer insulating film 52B. In particular, the deepest hole, that is, the minimum thickness of the inter-electrode insulating film 52B is formed so that the potential V5 at the lower surface of the liquid crystal layer 20 in this region becomes the maximum driving voltage _VLC . In addition, when there are many gradations, the electrode interlayer insulating film 52B having a higher dielectric constant is more likely to have more thickness steps.

The liquid crystal optical modulator 10E according to this embodiment is applied to a transmissive liquid crystal display device (see FIG. 9), like the liquid crystal optical modulator 10 according to the first embodiment. When the voltage V _DD is applied by the AC power supply 91, as shown in FIG. 15, the potential V5 on the lower surface of the liquid crystal layer 20 in the region where the thickness of the electrode interlayer insulating film 52B is the smallest (the hole is the deepest) is the maximum driving voltage. becomes _VLC . As described above, the potential at the lower surface of the liquid crystal layer 20 above the opening 32a is proportional to the distance d between the liquid crystal layer 20 and the lower electrode 31, and is proportional to the potential V1 (=V _DD ) of the lower electrode 31. descend. Therefore, for each opening 32a, a voltage corresponding to the thickness of the electrode interlayer insulating film 52B at the opening 32a is applied to the liquid crystal layer 20 thereon. As a result, for each opening 32a, the liquid crystal layer 20 thereon has an inclination of the liquid crystal molecules 2 corresponding to the thickness of the electrode interlayer insulating film 52B directly below. In such a liquid crystal display device, the light (for example, left-handed circularly polarized light) incident on the opening 32a of the liquid crystal optical modulator 10E causes the liquid crystal layer 20 to move to a position corresponding to the thickness of the electrode interlayer insulating film 52B in this region. The polarized state is changed by a phase difference δ (TN method: 0≦δ<π, VA method: 0<δ≦π) and transmitted. Then, the amount of light corresponding to the changed polarization state is transmitted through the polarizing plate 72 and emitted. The liquid crystal layer 20 on the opening 32a with the maximum thickness of the electrode interlayer insulating film 52B is applied with a voltage V _LC ' to display a desired gradation that is the second darkest (next to black). It becomes phase difference.

In this way, while the entire liquid crystal optical modulator 10E has the lower electrode 31, the lower surface of the liquid crystal layer 20 on each opening 32a is set to a desired potential, and the liquid crystal layer 20 is made to have a different phase difference δ. can be done. Then, the liquid crystal display device including the liquid crystal light modulator 10E, like the liquid crystal display device 100 according to the first embodiment, receives light from the entire surface, and the area where the opening 32a of the common electrode 32 on the opposite side is formed. Since light can be extracted only from the openings 32a and the amount of light can be changed for each opening 32a, a desired image can be displayed by the pattern of the openings 32a and the thickness of the openings 32a of the electrode interlayer insulating film 52B. In the liquid crystal display device including the liquid crystal optical modulator 10E, the common electrode 32 and the lower electrode 31 are connected to GND, and the upper electrode 41 is connected to the non-GND terminal of the AC power supply 91, as in the liquid crystal display device 100. By connecting, light can be emitted from the entire surface. In this embodiment, the voltage of the AC power supply 91 is set so that a voltage equal to or higher than the maximum driving voltage V _LC is applied to the liquid crystal layer 20 in the region of the maximum thickness in the opening 32a of the electrode interlayer insulating film 52B. .

(Modification)
In this embodiment, gradation display is possible not only by the difference in the thickness of the electrode interlayer insulating film separating the liquid crystal layer and the lower electrode, but also by the difference in relative permittivity. As shown in FIG. 16, in the liquid crystal optical modulator 10F according to the modification of the second embodiment of the present invention, an opening is also formed in the electrode interlayer insulating film 52C in the region where the opening 32a of the common electrode 32 is formed. Buried insulating layers (insulating layers) 5b and 5c made of insulating materials having different dielectric constants are formed for each opening 32a.

The embedded insulating layers 5 b and 5 c are selected from the insulating materials listed as the material for the inter-electrode insulating film 52 . Here, the buried insulating layer 5b made of the same material as the electrode interlayer insulating film 52C is provided in the opening 32a on the left side, and an insulating material having a higher dielectric constant (high dielectric constant insulating material) is provided in the opening 32a on the right side. ) is provided. The liquid crystal optical modulator 10F can display one more gradation than the number of types of materials (steps of relative permittivity) of the embedded insulating layers 5b and 5c. The buried insulating layers 5b and 5c are formed in the region where the buried insulating layer with the highest dielectric constant is provided when a voltage V _DD is applied between the electrodes 31 and 41 (potential V0 of the upper electrode 41=0V). The potential V5 on the lower surface of the liquid crystal layer 20 is lowered to the maximum drive voltage V _LC , and the potential V7 on the lower surface of the liquid crystal layer 20 in the region where the buried insulating layer with the lowest dielectric constant is provided is lowered to the minimum drive voltage V _LC '. The material and thickness are designed to allow (see FIG. 15).

The liquid crystal optical modulator 10F according to this modified example is applied to a transmissive liquid crystal display device (see FIG. 9), like the liquid crystal optical modulator 10E according to the above embodiment. A liquid crystal display device including the liquid crystal optical modulator 10F can take out light only from the area where the openings 32a of the common electrode 32 are formed, and can take out the light by changing the amount of light for each opening 32a. In the liquid crystal display device including the liquid crystal optical modulator 10F, the common electrode 32 and the lower electrode 31 are connected to GND, and the upper electrode 41 is connected to the AC power supply 91, as in the liquid crystal display device including the liquid crystal optical modulator 10E. Light can be emitted from the entire surface by connecting to a terminal on the non-GND side.

Further, this modification may be combined with the above-described embodiment so that the thicknesses of the embedded insulating layers 5b and 5c may be changed. Further, the holes having different depths in the electrode interlayer insulating film 52B of the embodiment shown in FIG. 14 may be filled with an insulating material having a dielectric constant different from that of the electrode interlayer insulating film 52B to form a flat surface. When filled with an insulating material having a dielectric constant higher than that of the electrode interlayer insulating film 52B, the applied voltage is higher in the liquid crystal layer 20 on the region where the electrode interlayer insulating film 52B has a smaller thickness. On the other hand, when filled with an insulating material having a dielectric constant lower than that of the electrode interlayer insulating film 52B, the applied voltage is higher in the liquid crystal layer 20 on the region where the electrode interlayer insulating film 52B is thicker.

The liquid crystal display devices including the liquid crystal optical modulators 10E and 10F according to the present embodiment and the modified examples are, like the liquid crystal display devices 100 and 100B according to the first embodiment, integral and holographic stereoscopic image display devices. can be used (see FIGS. 10 and 11). Also, the liquid crystal optical modulators 10E and 10F can be provided with a lower electrode 31A and a substrate 62A that reflect light, and can be made into reflective spatial optical modulators (see FIG. 12).

As described above, according to the liquid crystal light modulators according to the second embodiment and its modification of the present invention, similarly to the first embodiment, a liquid crystal display device having fine pixels and capable of displaying a desired image can be obtained. Furthermore, the image has a high image quality due to multi-gradation display.

[Third embodiment]
In the liquid crystal optical modulators according to the first and second embodiments and modifications thereof, the common electrode can be arranged on either the light incident side or the light emitting side with respect to the liquid crystal layer. Therefore, by providing a common electrode on both sides of the liquid crystal layer and forming opening patterns different from each other, two kinds of images can be displayed. A liquid crystal optical modulator according to the third embodiment will be described below. Elements that are the same as those in the first and second embodiments (see FIGS. 1 to 16) are denoted by the same reference numerals, and descriptions thereof are omitted.

(liquid crystal optical modulator)
As shown in FIG. 17, the liquid crystal optical modulator 10D according to the third embodiment of the present invention includes a liquid crystal layer 20, an upper electrode 41 and a lower electrode 31 sandwiching the liquid crystal layer 20 from above and below, and a structure between the lower electrode 31 and the liquid crystal layer 20. A common electrode 32 having an opening 32a formed therebetween, a common electrode 42 having an opening 42a formed between the upper electrode 41 and the liquid crystal layer 20, and an electrode insulating the common electrode 32 and the lower electrode 31 from each other. An interlayer insulating film 52 and an electrode interlayer insulating film 51 for insulating the common electrode 42 and the upper electrode 41 are provided. The liquid crystal optical modulator 10D further includes alignment films 21 and 22 in contact with the upper and lower surfaces of the liquid crystal layer 20, respectively, a transparent substrate 61 above the upper electrode 41, and a transparent substrate 62 below the lower electrode 31. FIG. That is, the liquid crystal light modulator 10D has a configuration in which a common electrode 42 and an inter-electrode insulating film 51 are added between the upper electrode 41 and the liquid crystal layer 20 of the liquid crystal light modulator 10 according to the first embodiment. As with the liquid crystal light modulator 10, the liquid crystal light modulator 10D transmits light incident on the entire surface from either the upper side or the lower side and emits the light to the other side. It is a transmissive spatial light modulator that changes its direction. The liquid crystal optical modulator 10D is applied to a liquid crystal display device that displays two fixed patterns as images.

The common electrode 42 is provided between the upper electrode 41 and the liquid crystal layer 20 and, like the common electrode 32 , prevents the electrodes 31 and 41 from partially generating an electric field in the liquid crystal layer 20 . That is, the common electrode 42 is formed with an opening 42a so as to leave a region for generating an electric field. The common electrode 42 can have the same configuration as the common electrode 32, except that the arrangement pattern of the openings 42a is different from that of the common electrode 32. FIG. The apertures 42a are formed in the pixels for bright display of the image to be displayed, and this image can be made independent of the fixed pattern by the arrangement of the apertures 32a of the common electrode 32. FIG. Moreover, the planar view shape of the opening 42a may be the same as or different from that of the opening 32a. The electrode interlayer insulating film 51 is provided between the upper electrode 41 and the common electrode 42 in order to insulate them. Similar to the electrode interlayer insulating film 52, the electrode interlayer insulating film 51 is selected from the above insulating materials and designed to have an appropriate thickness. be done.

(Liquid crystal display device)
A liquid crystal optical modulator 10D according to the third embodiment of the present invention is used in a liquid crystal display device in the same manner as the liquid crystal optical modulator 10 according to the first embodiment. As shown in FIGS. 18A and 18B, the liquid crystal display device 100D according to the embodiment of the present invention includes a liquid crystal optical modulator 10D and polarizing plates (polarizers) 71 arranged above and below the liquid crystal optical modulator 10D. , 72, and phase difference plates 73 and 74 between the liquid crystal optical modulator 10D and the polarizing plates 71 and 72, respectively. Further, when displaying a full-color image, the liquid crystal display device 100D has a color filter array 75 on the output side of the liquid crystal optical modulator 10D (see FIG. 10). The liquid crystal display device 100D can be irradiated with light from one of the upper and lower sides and can display an image on the other side. Here, the liquid crystal display device 100D will be described as being irradiated with light from above and displaying an image downward. .

(Operation of liquid crystal optical modulator and liquid crystal display device)
Operations of the liquid crystal optical modulator and the liquid crystal display device according to the third embodiment will be described with reference to FIGS. 18A, 18B, and 19. FIG. As shown in FIG. 18A, the liquid crystal optical modulator 10D has an AC power supply 91 connected between electrodes 31 and 41, and a common electrode 32 and a common electrode 42 are short-circuited and connected to a power supply device 93. As shown in FIG. The power supply device 93 receives a voltage from the AC power supply 91 and outputs a voltage smaller than this voltage in synchronization with the AC power supply 91 . Further, the terminal on the upper electrode 41 side of the AC power supply 91 is connected to GND (0 V). Here, the potentials of the electrodes 31, 41, 32, and 42 are expressed as V1, V4, V2, and V3, the potential at the lower surface of the liquid crystal layer 20 above the opening 32a of the common electrode 32 is V5, and the potential below the opening 42a of the common electrode 42 is V5. is represented as V6. Here, the potential drop due to the alignment films 21 and 22 is neglected because the thickness thereof is sufficiently small with respect to the liquid crystal layer 20 . The inter-electrode insulating film 51 and the inter-electrode insulating film 52 have the same structure (relative permittivity, thickness).

When a voltage V _DD (V4=0 V, V1=V _DD ) is applied between the electrodes 31-41, the common electrodes 32-42 (outside the opening 32a and outside the opening 42a) short-circuited to the same potential (V2=V3) ), no voltage is applied to the liquid crystal layer 20 . Further, as described in the first embodiment, the potential V5 at the lower surface of the liquid crystal layer 20 above the opening 32a of the common electrode 32 drops from the potential V1 of the lower electrode 31 by a potential difference ΔV (=|V1−V5|). However, the potential difference ΔV depends on the thickness and dielectric constant of the inter-electrode insulating film 52 separating the liquid crystal layer 20 and the lower electrode 31 (see FIG. 19). Since the inter-electrode insulating film 51 and the inter-electrode insulating film 52 have the same structure, the potential difference between V4-V6 can also be represented by ΔV. That is, V5=V _DD -ΔV and V6=ΔV. Therefore, a voltage of |V5-V6|=V _DD -2ΔV is applied to the liquid crystal layer 20 below the opening 42a and above the opening 32a. In this region, the voltage (maximum driving voltage) V _LC is applied so that the liquid crystal molecules 2 stand upright and the phase difference δ of the liquid crystal layer 20 becomes 0 (|V5−V6|≧V _LC ). Set the voltage V _DD (≧V _LC +2ΔV). With such a configuration, a vertical electric field (indicated by hatched upward arrows in the figure) is generated in the region of the liquid crystal layer 20, causing the liquid crystal molecules 2 to stand upright.

On the other hand, a voltage of potential difference |V5-V3| is applied to the liquid crystal layer 20 above the opening 32a and below the common electrode 42 (outside the opening 42a). In order to apply the maximum drive voltage V _LC also in this region, the potential V3 of the common electrode 42 is set to ΔV, that is, the power source, so that |V5−V3|=|V5−V6|≧V _LC Set the voltage V _DD ' (=ΔV) of the device 93 . Therefore, V2=V3=ΔV. At this time, above the common electrode 32 (outside the opening 32a) and below the opening 42a, the potential difference |V2-V6|=0 V, and no voltage is applied to the liquid crystal layer 20. FIG. Thus, in the liquid crystal optical modulator 10D, an electric field is generated only in the region where the common electrode 32 is not provided (above the opening 32a), and is not affected by the presence or absence of the opening 42a of the upper common electrode 42. FIG. As a result, the liquid crystal layer 20 is applied with the maximum driving voltage V _LC above the openings 32a so that the liquid crystal molecules 2 stand upright and the phase difference δ becomes 0. The phase difference δ becomes maximum (π) in this state.

When the liquid crystal optical modulator 10D is in such a state and the natural light L _uP is incident on the liquid crystal display device 100D from above, the polarizing plate 71 and the retardation plate 73 are applied as described in the first embodiment with reference to FIG. The left-handed circularly polarized light L enters the liquid crystal layer 20 . Then, the light is linearly polarized light in the 90° direction only from the area where the openings 32a of the common electrode 32 are formed and is extracted downward from the liquid crystal display device 100D, so that a desired image can be displayed according to the pattern of the openings 32a.

Next, the liquid crystal optical modulator 10D switches the connection with the AC power supply 91 connected between the electrodes 31 and 41 by the switches 95a and 95b so that the lower electrode 31 side of the AC power supply 91 is switched as shown in FIG. 18B. terminal is connected to GND (0 V). When the voltage V _DD is applied between the electrodes 31 and 41 in such a state, V1=0 V and V4=V _DD , so that the potential V1 and the potential V4 are interchanged. Also, since |V1-V5|=|V4-V6|=ΔV, V5=ΔV and V6=V _DD -ΔV, and the potential V5 and the potential V6 are switched. 18A, the common electrodes 32 and 42 receive a current of voltage V _DD ' (=ΔV) from the power supply device 93, so that V2=V3=ΔV.

As in FIG. 18A, no voltage is applied to the liquid crystal layer 20 between the common electrodes 32 and 42 (outside the opening 32a and outside the opening 42a). A voltage of |V5-V6|=V _DD -2ΔV≧V _LC is applied to the liquid crystal layer 20 below the opening 42a and above the opening 32a. ) occurs. On the other hand, above the opening 32a and below the common electrode 42 (outside the opening 42a), the potential difference |V5−V3|=0 V, and no voltage is applied to the liquid crystal layer 20. FIG. On the other hand, above the common electrode 32 (outside the opening 32a) and below the opening 42a, a voltage with a potential difference |V2-V6|≧V _LC is applied to the liquid crystal layer 20 to generate an electric field. Thus, in the liquid crystal optical modulator 10D, an electric field is generated only in the region (below the opening 42a) without the common electrode 42, and is not affected by the presence or absence of the opening 32a of the common electrode 32 on the lower side. As a result, the liquid crystal layer 20 is applied with the maximum driving voltage V _LC under the opening 42a, the liquid crystal molecules 2 stand upright, and the phase difference δ becomes 0. The phase difference δ becomes maximum (π) in this state.

When the liquid crystal light modulator 10D is in such a state, when the natural light L _uP is incident on the liquid crystal display device 100D from above, it becomes linearly polarized light in the direction of 90° only from the area where the opening 42a of the common electrode 42 is formed, and the liquid crystal display device 10D is displayed. A desired image can be displayed by the pattern of the openings 42a as it is taken out downward from the device 100D.

In this manner, the liquid crystal optical modulator 10D has the upper electrode of the liquid crystal layer 20 provided in two layers with a dielectric sandwiched therebetween like the lower electrode, and an opening to the common electrode 42 on the side closer to the liquid crystal layer 20. 42a, and furthermore, when a voltage is applied between the electrodes 31-41, the connection can be switched such that the terminals of the AC power supply 91 are exchanged. An electric field can be locally generated in a two-dimensional pattern corresponding to the desired one-sided arrangement of apertures 42a of 42. FIG. As a result, the liquid crystal display device 100D can selectively display two images corresponding to each pattern of the openings 32a of the common electrode 32 and the openings 42a of the common electrode 42. FIG.

Like the liquid crystal display device 100 according to the first embodiment, the liquid crystal display device 100D can emit light from the entire surface. For this purpose, for example, in FIG. 18A (V4=0V, V1=V _DD ), the switch 94 disconnects the common electrode 32 from the common electrode 42 and switches the connection with the power supply device 93 to the power supply device 92. . Like the power supply 93 , the power supply 92 receives a current from the AC power supply 91 and outputs a current of voltage V _DD −ΔV in synchronization with the AC power supply 91 . That is, since V2=V _DD -ΔV and V3=V _DD '=ΔV, V2=V5 and V3=V6. Further, the potential difference |V2-V3|=V _DD -2ΔV≧V _LC is established, and the voltage V _LC is also applied to the liquid crystal layer 20 between the common electrodes 32 and 42 (outside the opening 32a and outside the opening 42a).

In this embodiment, the liquid crystal layer 20 may be of the VA method or surface-stabilized ferroelectric liquid crystal (SSFLC), as in the liquid crystal optical modulator 10 according to the first embodiment. When generating electric fields in opposite directions on the common electrode 32 and on the opening 32a of the liquid crystal layer 20 to which ferroelectric liquid crystal is applied, as described above, the positive electrode of the first power supply is connected to the lower electrode 31, The negative electrode is connected to GND and upper electrode 41 respectively, and the second power supply has its positive electrode connected to GND and upper electrode 41 and its negative electrode to common electrode 32 . Furthermore, in order to equalize the potential on the upper surface of the liquid crystal layer 20 (V3=V6), the negative electrode of the third power supply is connected to the common electrode 42, and the positive electrode is connected to GND (and the upper electrode 41). The voltage applied to the liquid crystal layer 20 to generate an upward electric field of necessary strength is represented by V _LC 1, and the applied voltage to generate a downward electric field is represented by V _LC 2. Each of the voltages V DD1 , V _DD2 and V _DD3 satisfies V _DD1 ≧V _LC1 +2ΔV, V _DD2 ≧V _LC2 +ΔV and V _DD3 = _ΔV . In order to generate electric fields opposite to each other under the common electrode 42 and under the opening 42a of the liquid crystal layer 20, the connection with the DC power supply is switched between the upper and lower electrodes.

The liquid crystal display device 100D according to the present embodiment has a two-dimensional fixed pattern formed by arranging the openings 32a in the common electrode 32 or the openings 42a in the common electrode 42 on the surface (polarizing plate 72) opposite to the incidence of external light or the like. can be selectively displayed in two ways. Further, by providing a color filter array 75 (see FIG. 10) on the light exit side of the liquid crystal optical modulator 10D, a full-color image can be displayed. In this case, both the common electrode 32 and the common electrode 42 have openings 32a, 42a so as to arrange the pixels of each color according to the regions facing the color filters of each of R, G, and B in the color filter array 75. array is designed. Further, the liquid crystal display device 100D can be used for an integral type or holographic type stereoscopic image display device, like the liquid crystal display devices 100 and 100B according to the first embodiment (see FIGS. 10 and 11). In a holographic stereoscopic image display device (holographic device), one of the common electrodes 32 and 42 can display a stereoscopic image, and the other can display a two-dimensional image. The liquid crystal optical modulator 10D can also be a reflective spatial optical modulator by disposing a reflector on the side opposite to the incident side of light, or by providing a lower electrode 31A and a substrate 62A that reflect light. (See FIG. 12).

(Modification)
The liquid crystal display device 100D according to this embodiment may not include the power supply device 93, and the common electrodes 32, 42 may be connected to GND (0 V) together with the upper electrode 41 (FIG. 18A) or the lower electrode 31 (FIG. 18B). . Further, in such a liquid crystal display device 100D, the electrode interlayer insulating film 51 and the electrode interlayer insulating film 52 of the liquid crystal optical modulator 10D are replaced with the liquid crystal optical modulators 10E and 10F (FIG. 14) according to the second embodiment and its modification. , FIG. 16), multi-gradation display can be performed.

As described above, according to the liquid crystal light modulators according to the third embodiment and its modification of the present invention, a liquid crystal display device having fine pixels and capable of displaying a desired image can be obtained as in the first embodiment. Furthermore, two types of images can be selectively displayed.

In order to confirm the effects of the present invention, a simulation was performed to observe the optical output characteristics of a sample simulating the liquid crystal optical modulator according to the first embodiment of the present invention shown in FIG.

(Sample creation)
Sample 1 includes, from the bottom, a glass substrate, a lower electrode: ITO (thickness 20 nm), an inter-electrode insulating film: SiO ₂ film (thickness 50 nm), a common electrode: ITO (thickness 20 nm), an alignment film, and a liquid crystal layer. (thickness 1 μm), alignment film, upper electrode: ITO film (thickness 20 nm), and glass substrate. As shown on the coordinate plane in FIG. 20, the common electrode had a checker pattern in which two 0.8 μm square openings were formed diagonally at a pitch of 1.0 μm. The liquid crystal layer was a homogeneously aligned nematic liquid crystal, and the upper and lower alignment films were made of a polyimide material and rubbed in the y direction (90° direction) of FIG.

(measurement)
Using a liquid crystal simulator (LCDMaster, manufactured by Shintech Co., Ltd.), the upper electrode and common electrode of Sample 1 and one terminal of the AC power supply were fixed at 0 V, the other terminal was connected to the lower electrode, and the voltage was adjusted to 1 kHz at ±7 V. The potential distribution and the liquid crystal orientation were obtained under the condition that an AC voltage was applied. The potential distribution and the liquid crystal orientation are the cross-sectional distribution along the yz direction on the dashed line in FIG. 20, and the plane distribution along the xy plane 10 nm above the surface of the common electrode. was extracted. Furthermore, a polarizing plate (polarizer) is placed above the sample 1 (light incident side) with its transmission axis directed at 45°, and a polarizing plate (analyzer) is placed below (light exit side) with its transmission axis directed at 135°. ) was placed. Then, a laser beam with a wavelength of 633 nm was irradiated from above the upper polarizing plate, and a plane distribution of transmittance reflecting the entire thickness of the liquid crystal layer was obtained.

FIG. 21 shows the potential distribution and liquid crystal orientation in the cross section, and FIG. 22 shows the potential distribution and liquid crystal orientation in the plane. 23 shows the planar distribution of the transmittance together with the liquid crystal orientation of FIG. The equipotential lines in the potential distribution map are in 1V increments. Further, in FIG. 21, the upper and lower electrodes are indicated by white long broken lines, the common electrode is indicated by white broken lines, and the surface of the electrode interlayer insulating film (interface with the liquid crystal layer) at the opening of the common electrode is indicated by dotted lines. In FIGS. 22 and 23, outlines of common electrode openings are indicated by dotted white lines.

In FIGS. 21 and 22, the potential at the interface between the liquid crystal layer and the common electrode is 0 V, and the potential at the interface between the electrode interlayer insulating film in the opening of the common electrode reaches a maximum of about +4 V at the center of the opening. In FIG. 22, equipotential lines in the opening of the common electrode are +3V, +2V, and +1V in order from the inside. Then, due to the electric field generated between the opening and the upper electrode with a potential of 0 V, the liquid crystal molecules on the opening were raised from the substrate surface and tilted, and the higher the potential, the closer the vertical became. On the other hand, the range of leakage of the electric field to the outside of the aperture was narrow, and the tilt of the liquid crystal molecules was small even in the leaked region.

As shown in FIG. 23, the polarizing plates arranged above and below Sample 1 provide white display in the region where the liquid crystal molecules maintain their horizontal alignment, and gray to black display in the region where the liquid crystal molecules are raised. As the direction of the molecule (major axis direction) approaches vertical, the transmittance decreases and is displayed in black. It was observed that in some regions above the opening of the common electrode, the rise angle of the liquid crystal molecules was large (close to vertical), so that the transmittance was almost 0%, resulting in black display. In addition, since an electric field leaks from the opening toward the common electrode with a potential of 0 V, some of the liquid crystal molecules near the outside of the opening also stand up, and as a result, a blackish display area is also confirmed outside the opening. rice field. However, it remains in a range of less than 0.2 μm outside the aperture, and it is generally difficult to say that it extends to the aperture of the adjacent pixel. On the other hand, on the opening of the common electrode, there was a region where liquid crystal molecules were oriented obliquely due to electric field leakage obliquely in a plan view. In particular, in the region adjacent to the common electrode (outside the aperture) in the y direction, the liquid crystal molecules are tilted in the y direction and overlap with the 90° direction, which is the orientation direction in the yz no electric field state, resulting in a large tilt (rising angle is small), and as a result, the shape of the area displayed in black is smaller than the shape of the opening of the common electrode, and is partially recessed inward.

As described above, according to the liquid crystal light modulator according to the first embodiment of the present invention, it is confirmed that black and white display can be separated even in an area of less than 1 μm where one side is shorter than the cell thickness. In particular, it was relatively easy to secure a region to be in a no-electric-field state by the common electrode.

As in Example 1, simulation was performed to observe the optical output characteristics of samples simulating the liquid crystal optical modulators according to the second embodiment and its modification shown in FIGS. 14 and 16 .

(sample)
Samples 2 and 3 are, in order from the bottom, a glass substrate, lower electrode: ITO (thickness 20 nm), electrode interlayer insulating film: SiO ₂ film (thickness 100 nm), common electrode: ITO (thickness 20 nm), alignment film, A liquid crystal layer (thickness 1 μm), an alignment film, an upper electrode: an ITO film (thickness 20 nm), and a glass substrate were used. As shown on the coordinate plane in FIG. 24, the common electrode has a shape in which four 2×2 square openings of 0.8 μm square are arranged at a pitch of 1.0 μm. In sample 2, the electrode interlayer insulating film was further thinned to a thickness of 20 nm in the two openings (area a1 in FIG. 24) on the diagonal of the common electrode (see FIG. 14). On the other hand, in sample 3, the inter-electrode insulating film was completely removed in the two openings (area a1 in FIG. 24) on the diagonal of the common electrode, and a 100-nm-thick insulating film was left behind. A high dielectric constant insulating material (κ=40) having a dielectric constant ten times that of the electrode interlayer insulating film (κ=4) was embedded (see FIG. 16). Otherwise, the configuration was the same as that of the sample of Example 1.

(measurement)
For each of Samples 2 and 3, the upper electrode, the common electrode, and one terminal of the AC power supply were fixed at 0 V, the other terminal was connected to the lower electrode, and an AC voltage of ±5 V and 1 kHz was applied. The potential distribution and the liquid crystal orientation were obtained in the same manner as in Example 1. Furthermore, in the same manner as in Example 1, polarizing plates were placed above and below Samples 2 and 3, and a laser beam was irradiated to determine the planar distribution of the transmittance. FIG. 25 shows the potential distribution and liquid crystal orientation in the cross section of Sample 2, and FIG. 26 shows the plane distribution of transmittance. FIG. 27 shows the potential distribution and liquid crystal orientation in the cross section of Sample 3, and FIG. 28 shows the plane distribution of transmittance.

In FIG. 25, the potential at the interface between the liquid crystal layer and the electrode interlayer insulating film having a thickness of 100 nm over the opening on the left side of the common electrode was approximately +2.5 V at the center of the opening. On the other hand, the potential at the interface with the 20 nm-thick electrode interlayer insulating film on the right opening exceeded +4 V at the center of the opening, and the drop from the voltage of the AC power supply was small. As a result, the liquid crystal molecules stood almost vertically on the right opening, while they were tilted on the left opening. As in Example 1, the rise angle was small at the peripheral edges on all openings. As shown in FIG. 26, in the sample 2 in which such an electric field was generated, the region of the electrode interlayer insulating film having a thickness of 20 nm was displayed in black, and the region of the electrode interlayer insulating film having a thickness of 100 nm was displayed in gray. A halftone display was obtained. In FIG. 26 and FIG. 28 described later, the edge of the opening of the common electrode looks like a bright (white) line because the orientation of the liquid crystal molecules at the interface with the electrode of the liquid crystal layer is horizontal due to the setting of the simulation conditions. due to being fixed. Therefore, in samples 2 and 3, the liquid crystal molecules adjacent to the edge of the opening of the common electrode with a height (thickness) of 20 nm are also horizontally fixed, resulting in white display. The same is true for Sample 1 of Example 1, but in FIG. 23, the display scale is as wide as the transmittance of 0 to 70%, so the white display at the edge of the aperture is difficult to see.

In FIG. 27, the potential at the interface between the liquid crystal layer and the inter-electrode insulating film over the opening on the left side of the common electrode was approximately +2.5 V at the center of the opening. On the other hand, the potential at the interface with the film of the high-dielectric-constant insulating material over the opening on the right side exceeded +4 V at the center of the opening, and the drop from the voltage of the AC power source was small. As a result, the liquid crystal molecules stood almost vertically on the right opening, while they were tilted on the left opening. As in Example 1, the rise angle was small at the peripheral edges on all openings. As shown in FIG. 28, sample 2 in which such an electric field was generated exhibited black in the region provided with the film of the high dielectric constant insulating material (κ=40), and the electrode interlayer insulating film (κ=4) provided a black display. In the area of , a gray halftone display was obtained.

As described above, it was confirmed that the liquid crystal optical modulators according to the second embodiment and the modified example of the present invention are capable of halftone display with a common power supply.

The embodiments for carrying out the liquid crystal optical modulator, the liquid crystal display device, and the stereoscopic image display device of the present invention have been described above, but the present invention is not limited to these embodiments. Various changes are possible within the range shown in .

100, 100A, 100B, 100C, 100D liquid crystal display device 10, 10A, 10B, 10D, 10E, 10F liquid crystal optical modulator 200 stereoscopic image display device 200B holography device (stereoscopic image display device)
200C projection type display device 20, 20A liquid crystal layer 2 liquid crystal molecules 21, 22 alignment film 31, 31A lower electrode 32, 32B common electrode 32a opening 41 upper electrode 42 common electrode 42a opening 51 inter-electrode insulating film 52, 52A, 52B, 52C Inter-electrode insulating film 5a, 5b, 5c Buried insulating layer (insulating layer)
61, 62 transparent substrate 62A substrate 71, 72 polarizing plate (polarizer)
73, 74 retardation plate 75 color filter array 80, 80A light source device (light source)
8 Light source device (light source)
85 lens array 91 AC power supply (power supply)
92, 93 power supply

Claims (11)

A liquid crystal optical modulator comprising a liquid crystal layer, and an upper electrode and a lower electrode for applying a voltage vertically across the liquid crystal layer,
A common electrode having a plurality of openings formed between the lower electrode and the liquid crystal layer, and an inter-electrode insulating film for insulating the common electrode and the lower electrode are further laminated. liquid crystal light modulator. A common electrode having a plurality of openings formed between the upper electrode and the liquid crystal layer, and an inter-electrode insulating film for insulating the common electrode and the upper electrode are further laminated. 2. The liquid crystal optical modulator according to claim 1, wherein the upper and lower common electrodes have mutually different arrangements of the plurality of openings in plan view. 3. The liquid crystal optical modulator according to claim 1, wherein the opening of said common electrode is filled with an insulating layer. 3. The liquid crystal optical modulator according to claim 1, wherein said inter-electrode insulating film has an opening inside an opening of said common electrode laminated with said inter-electrode insulating film in plan view. further comprising an insulating layer embedded in an opening formed in the stacked common electrode and the electrode interlayer insulating film;
5. The liquid crystal optical modulator according to claim 4, wherein the insulating layer has a different thickness depending on the opening. further comprising an insulating layer embedded in an opening formed in the stacked common electrode and the electrode interlayer insulating film;
6. The liquid crystal optical modulator according to claim 4, wherein said insulating layer is made of a material having a different dielectric constant depending on said opening. 7. The liquid crystal light modulator according to claim 1, wherein the plurality of openings of the common electrode are arranged in a pattern of a computer-generated hologram. 8. A liquid crystal optical modulator according to claim 1, and a polarizer arranged above or below the liquid crystal optical modulator, wherein the polarizer is arranged on the side of the liquid crystal optical modulator. A liquid crystal display device that displays an image by irradiating light on the 8. The liquid crystal optical modulator according to claim 1, and two polarizers arranged above and below the liquid crystal optical modulator, and A liquid crystal display device that displays an image on the other side by being irradiated with light. 10. The liquid crystal display device according to claim 8 or 9, a light source for irradiating the liquid crystal display device with light, and a power source connected to the upper electrode, the lower electrode, and the common electrode of the liquid crystal optical modulator of the liquid crystal display device. and a stereoscopic image display device. 8. The liquid crystal optical modulator according to claim 1, a light source for irradiating polarized light onto the liquid crystal optical modulator, an upper electrode, a lower electrode, and a common electrode of the liquid crystal optical modulator. A stereoscopic image display device comprising: a power source to be connected;

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