Optical phase modulation element and display device

Abstract

This optical phase modulation element (10) comprises: a pixel provided with a liquid crystal layer (152) that adjusts the phase of incident light, a pixel electrode that is disposed across the liquid crystal layer (152) and applies a voltage to the liquid crystal layer (152), and a counter electrode; and a first partial reflection plate (130) and a second partial reflection plate (160) that are disposed across a first alignment film (151), the liquid crystal layer (152), and a second alignment film (153), and transmit a part of the incident light and reflect a part of the incident light. The first partial reflection plate (130) transmits at least a part of the incident light from a light source to be incident on the second partial reflection plate (160), and reflects at least a part of the light reflected by the second partial reflection plate (160) and causes the light to enter the second partial reflection plate (160) again. The second partial reflection plate (160) reflects at least a part of the light transmitted through the first partial reflection plate (130), causes the light to enter the first partial reflection plate (130) again, and transmits at least a part of the light reflected by the first partial reflection plate (130).

Description

Optical phase modulation element and display device

[0001] The present disclosure relates to an optical phase modulation element and a display device.

[0002] Display devices equipped with liquid crystal panels are widely used. These liquid crystal panels are composed of multiple pixels arranged in a two-dimensional matrix. Each pixel is equipped with a pixel circuit that applies a drive voltage to the liquid crystal layer. If this drive voltage differs significantly between pixels, crosstalk occurs. This occurs because an electric field is generated between adjacent pixels, disrupting the alignment of the liquid crystal at the edges of the pixels. This inter-pixel crosstalk, also known as disclination, causes degradation of image quality.

[0003] Liquid crystal panels that prevent such disclination have been proposed, such as a liquid crystal panel (light modulation panel) that has control electrodes between pixels and forms an electric field different from the electric field between the electrodes to control the alignment direction of the liquid crystal (see, for example, Patent Document 1).

[0004] JP 2014-137581 A

[0005] However, the above-mentioned prior art requires a circuit for supplying a control voltage to the control electrode, which makes the control circuit complicated.

[0006] Therefore, the present disclosure proposes an optical phase modulation element that reduces disclination using a control circuit with a simple configuration, and a display device that uses the optical phase modulation element.

[0007] The optical phase modulation element according to the present disclosure includes a pixel including a liquid crystal layer that adjusts the phase of incident light, a pixel electrode and a counter electrode that are arranged on either side of the liquid crystal layer and that apply a voltage to the liquid crystal layer, a first alignment film that is arranged adjacent to a surface of the liquid crystal layer that is close to the pixel electrode, and a second alignment film that is arranged adjacent to a surface of the liquid crystal layer that is close to the counter electrode, a pixel circuit that drives the pixel, a first substrate that supports the pixel electrode and the first alignment film, a second substrate that supports the counter electrode and the second alignment film, and a substrate that sandwiches the first alignment film, the liquid crystal layer, and the second alignment film. The optical system has a first partial reflector and a second partial reflector arranged in a manner such that they transmit a portion of incident light and reflect a portion of the incident light, wherein the first partial reflector transmits at least a portion of the incident light from a light source to make it incident on the second partial reflector and reflects at least a portion of the light reflected by the second partial reflector to make it incident again on the second partial reflector, and the second partial reflector reflects at least a portion of the light that has transmitted through the first partial reflector to make it incident again on the first partial reflector and transmits at least a portion of the light reflected by the first partial reflector.

[0008] FIG. 1 is a diagram illustrating a configuration example of an optical phase modulation element according to a first embodiment of the present disclosure. FIG. 2 is a diagram illustrating an optical phase modulation element according to an embodiment of the present disclosure. FIG. 3 is a diagram illustrating an optical phase modulation element according to an embodiment of the present disclosure. FIG. 4 is a diagram illustrating an example of a configuration of an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 5 is a diagram illustrating an example of a configuration of an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 6 is a diagram illustrating an example of a configuration of a first partial reflector according to the first embodiment of the present disclosure. FIG. 7 is a diagram illustrating an example of a configuration of a first partial reflector according to the first embodiment of the present disclosure. FIG. 8 is a diagram illustrating an example of a configuration of a second partial reflector according to the first embodiment of the present disclosure. FIG. 9 is a diagram illustrating another example of a configuration of the second partial reflector according to the first embodiment of the present disclosure. FIG. 10 is a diagram illustrating an example of a manufacturing method of an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 11 is a diagram illustrating an example of a manufacturing method of an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 1 is a diagram illustrating an example of a manufacturing method for an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 2 is a diagram illustrating an example of a manufacturing method for an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 3 is a diagram illustrating an example of a manufacturing method for an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 4 is a diagram illustrating an example of a manufacturing method for an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 5 is a diagram illustrating an example of a manufacturing method for an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 6 is a diagram illustrating an example of a manufacturing method for an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 7 is a diagram illustrating another configuration example of an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 8 is a diagram illustrating a configuration example of an optical phase modulation element according to a second embodiment of the present disclosure. FIG. 9 is a diagram illustrating a configuration example of an optical phase modulation element according to a third embodiment of the present disclosure.FIG. 1 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. FIG. 2 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. FIG. 3 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. FIG. 4 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. FIG. 5 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. FIG. 6 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. FIG. 7 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order. Note that in the following embodiments, the same components are designated by the same reference numerals, and redundant description will be omitted. 1. First embodiment 2. Second embodiment 3. Third embodiment 4. Configuration of display device

[0010] (1. First Embodiment) [Configuration of Optical Phase Modulation Element] FIG. 1 is a diagram showing a configuration example of an optical phase modulation element according to a first embodiment of the present disclosure. The figure is a block diagram showing a configuration example of an optical phase modulation element 10. This optical phase modulation element 10 is an element that controls the phase of incident light. The optical phase modulation element 10 includes a pixel array unit 11, a vertical drive unit 13, and a horizontal drive unit 12.

[0011] The pixel array section 11 is configured by arranging a plurality of pixels 100. The pixel array section 11 in FIG. 1 illustrates an example in which a plurality of pixels 100 are arranged in a two-dimensional matrix. Here, the pixel 100 includes a liquid crystal layer and a pixel circuit that generates a drive voltage to be applied to the liquid crystal layer, and adjusts the phase of incident light in accordance with an input signal. The drive voltage is applied via a pixel electrode (pixel electrode 102) and a counter electrode (counter electrode 103) that sandwich the liquid crystal layer. FIG. 1 illustrates the pixel electrode 102. The pixel circuit is also configured by a MOS transistor 101. The source of this MOS transistor 101 is connected to the pixel electrode 102.

[0012] Signal lines 14 and data lines 15 are wired to each pixel 100. The signal lines 14 transmit control signals for the pixel circuits. The data lines 15 transmit image signals. The signal lines 14 are arranged in rows in a two-dimensional matrix, and are wired in common to the multiple pixels 100 arranged in one row. The data lines 15 are arranged in columns in a two-dimensional matrix, and are wired in common to the multiple pixels 100 arranged in one column.

[0013] The vertical drive unit 13 generates control signals for the above-mentioned pixels 100. The vertical drive unit 13 in Fig. 1 generates control signals for each row of the two-dimensional matrix of the pixel array unit 11 and outputs them sequentially via signal lines 14.

[0014] The horizontal driving unit 12 generates image signals for the pixels 100 and outputs the generated image signals to the pixels 100. The horizontal driving unit 12 in FIG. 1 outputs image signals for each column of the pixel array unit 11 via data lines 15.

[0015] [Outline of Optical Phase Modulation Element] Figures 2A-2C are diagrams illustrating an optical phase modulation element according to an embodiment of the present disclosure. Figure 2A is a diagram illustrating an outline of the optical phase modulation element. The optical phase modulation element includes a liquid crystal layer 152 sandwiched between alignment films 151 and 153. This liquid crystal layer 152 is made of cholesteric liquid crystal. Of the light incident on the liquid crystal layer 152, the phase of the light having a polarization axis along the longitudinal direction of the liquid crystal molecules 154 in the liquid crystal layer 152 is changed (delayed). The phase of the incident light can be adjusted by adjusting the angle of the liquid crystal molecules 154.

[0016] The left side of Fig. 2A shows a reflective optical phase modulation element. In this reflective optical phase modulation element, incident light travels back and forth through the liquid crystal layer 152, so the amount of phase change can be increased. This allows the thickness d of the liquid crystal layer 152 to be reduced. However, the reflective optical phase modulation element has the problem of making the optical system complex.

[0017] The right side of Fig. 2A shows a transmissive optical phase modulation element. In this transmissive optical phase modulation element, incident light passes through the liquid crystal layer 152 once. Therefore, to obtain the same modulation amount as that of a reflective optical phase modulation element, the thickness of the liquid crystal layer 152 must be doubled. However, increasing the thickness of the liquid crystal layer 152 causes problems such as a decrease in response speed and an increase in disclination.

[0018] FIG. 2B is a diagram illustrating disclination. The optical phase modulation element in the figure further illustrates the counter electrode 103 and pixel electrode 102, and illustrates adjacent pixels 100a and 100b. The counter electrode 103 is disposed in common to the pixels 100a and 100b. Meanwhile, the pixel electrode 102 is disposed for each pixel 100, as described above. This figure illustrates a case where different voltages are applied to the pixel electrodes 102 of the pixels 100a and 100b. The arrows in the figure for pixel 100a represent the electric field. As shown in the figure, the electric field at the end of pixel 100a is curved toward pixel 100b, causing the alignment of the liquid crystal molecules 154 to become disordered. This disorder in the alignment of the liquid crystal molecules 154 causes disclination.

[0019] 2C shows the amount of phase modulation in the pixel array section 11. The horizontal axis of the figure represents the position in the pixel array section 11. The vertical axis of the figure represents the amount of phase modulation. The solid line graph in the figure represents an ideal case in which no disclination occurs. In contrast, the dotted line graph in the figure represents a case in which disclination occurs. It can be seen that the amount of phase change decreases due to disclination.

[0020] The optical phase modulation element of the present disclosure can improve the amount of phase modulation while preventing an increase in the thickness of the liquid crystal layer 152 .

[0021] [Configuration of Optical Phase Modulation Element] FIG. 3 is a diagram showing an example of the configuration of an optical phase modulation element according to the first embodiment of the present disclosure. This diagram is a schematic diagram showing an example of the configuration of an optical phase modulation element 10, and is a diagram illustrating the principle of the optical phase modulation element according to the present disclosure. The optical phase modulation element 10 in the diagram includes an alignment film 151, a liquid crystal layer 152, and an alignment film 153, as well as a first partial reflector 130 and a second partial reflector 160. The first partial reflector 130 and the second partial reflector 160 transmit a portion of incident light and reflect a portion of the incident light. The first partial reflector 130 and the second partial reflector 160 reflect the incident light so that it passes through the liquid crystal layer 152. This allows the light to pass through the liquid crystal layer 152 three times. The hollow arrows in the diagram represent incident light from a light source.

[0022] The first partial reflector 130 transmits at least a portion of the incident light from the light source to make it incident on the second partial reflector 160, and reflects at least a portion of the light reflected by the second partial reflector 160 to make it re-incident on the second partial reflector 160. At this time, the first partial reflector 130 emits reflected light having the same polarization direction as the incident light. Furthermore, the second partial reflector 160 reflects at least a portion of the light that has transmitted through the first partial reflector 130 to make it re-incident on the first partial reflector 130, and transmits at least a portion of the light reflected by the first partial reflector 130. At this time, the second partial reflector 160 emits reflected light having a polarization direction different from that of the incident light.

[0023] The first partial reflector 130 can be configured as a reflective polarizing plate that reflects one of the incident light beams having different linear polarization directions and transmits the other. The second partial reflector 160 can be configured as a quarter-wave plate 161 and a reflective holographic element 162. The quarter-wave plate 161 changes the polarization state of the incident light beam between linear polarization and circular polarization. The reflective holographic element 162 reflects one of the incident light beams having different circular polarization directions and transmits the other.

[0024] The incident light 301 is assumed to be linearly polarized light. The thick arrow in FIG. 3 indicates the polarization direction. As shown in FIG. 3, the incident light 301 is light with an upward polarization direction in FIG. 3. This incident light 301 passes through the first partial reflector 130, passes through the liquid crystal layer 152, and enters the quarter-wave plate 161 of the second partial reflector 160. The quarter-wave plate 161 converts the incident light 301 into circularly polarized light 302. As shown in FIG. 3, this light 302 is right-handed circularly polarized light. This light 302 is reflected by the reflective holographic element 162 of the second partial reflector 160 to become light 303, which enters the quarter-wave plate 161.

[0025] Light 303 is converted by quarter-wave plate 161 into linearly polarized light 304. This light 304 has a downward polarization direction as shown in FIG. 3 . Light 304 passes through liquid crystal layer 152 and enters first partial reflector 130. Because light 304 has a polarization direction that differs by 180 degrees from that of incident light 301, it is reflected by first partial reflector 130 and becomes light 305. This light 305 passes through liquid crystal layer 152 and enters quarter-wave plate 161. Light 305 is converted by quarter-wave plate 161 into left-handed circularly polarized light 306. Because this light 306 has a rotation direction different from that of light 302, it is transmitted through reflective holographic element 162 without being reflected.

[0026] In this way, the light incident on the optical phase modulation element 10 passes through the liquid crystal layer 152 three times. During two of these passes, the incident light (light 304 and light 305) has the same polarization state, and phase modulation by the liquid crystal layer 152 can occur.

[0027] 4 is a diagram showing a configuration example of an optical phase modulation element according to the first embodiment of the present disclosure. The diagram is a schematic cross-sectional view showing a configuration example of an optical phase modulation element 10. The optical phase modulation element 10 in the diagram is a specific embodiment of the optical phase modulation element 10 described in FIG. 3. The diagram shows a pixel 100 portion of a pixel array section 11. The optical phase modulation element 10 includes a first substrate 110, a wiring region 120, a first partial reflector 130, a protective film 141, a pixel electrode 102, alignment films 151 and 153, a liquid crystal layer 152, a second partial reflector 160, a counter electrode 103, and a second substrate 170.

[0028] The first substrate 110 is a substrate on which the wiring region 120 is formed and which supports the first partial reflector 130, the pixel electrodes 102, and the alignment film 151. The first substrate 110 can be made of, for example, quartz.

[0029] The wiring region 120 is a region where wiring and the like of the pixel 100 are formed. The wiring region 120 includes an interlayer insulating film 121 and wiring 122. The interlayer insulating film 121 is made of, for example, silicon oxide (SiO ２ ) The wiring 122 can be made of a conductive material. The wiring 122 can be arranged in multiple layers. A MOS transistor 101 that constitutes a pixel circuit is further arranged in the wiring region 120. This MOS transistor 101 is made of an organic semiconductor layer 123 that is arranged between two wirings 122. A light-shielding layer 124 is arranged on the top layer of the wiring region 120. This light-shielding layer 124 can be made of metal.

[0030] As described above, the first partial reflector 130 transmits at least a portion of the incident light from the light source to make it incident on the second partial reflector 160, and reflects at least a portion of the light reflected by the second partial reflector 160 to make it re-incident on the second partial reflector 160. The configuration of the first partial reflector 130 will be described in detail later.

[0031] The protective film 141 is laminated on the first partial reflector 130 to protect the first partial reflector 130. The protective film 141 is made of, for example, SiO ２ It can be configured as follows.

[0032] As described above, the pixel electrode 102 is an electrode that is disposed for each pixel 100 and applies a voltage to the liquid crystal layer 152. The pixel electrode 102 can be made of, for example, ITO (Indium Tin Oxide). A light-shielding portion 142 is disposed around the pixel electrode 102. The light-shielding portion 142 constitutes a black matrix.

[0033] The alignment films 151 and 153 align the liquid crystal molecules 154 in the liquid crystal layer 152. As described above, the liquid crystal layer 152 modulates the phase of incident light. The alignment film 151 is an example of a "first alignment film" in the present disclosure. The alignment film 153 is an example of a "second alignment film" in the present disclosure.

[0034] As described above, the second partial reflector 160 reflects at least a portion of the light that has passed through the first partial reflector 130 so that the light is incident on the first partial reflector 130 again, and transmits at least a portion of the light that has been reflected by the first partial reflector 130. As described above, the second partial reflector 160 includes a quarter-wave plate 161 and a reflective holographic element 162. A known quarter-wave plate can be used as the quarter-wave plate 161. The configuration of the reflective holographic element 162 will be described in detail later.

[0035] The counter electrode 103 is an electrode that is disposed in common to the plurality of pixels 100 and applies a voltage to the liquid crystal layer 152 of each pixel 100. The counter electrode 103 can be made of ITO. As shown in FIG. 4 , the pixel electrode 102 and the counter electrode 103 are disposed with the liquid crystal layer 152 sandwiched therebetween.

[0036] The second substrate 170 is a substrate that supports the counter electrode 103, the second partial reflector 160, and the alignment film 153. The second substrate 170 can be made of, for example, quartz.

[0037] It is preferable to arrange the first partial reflector 130 and the second partial reflector 160 in positions close to the liquid crystal layer 152. The first partial reflector 130 is preferably arranged in the vicinity of the pixel electrode 102. The first partial reflector 130 in FIG. 4 represents an example in which it is arranged in the vicinity of the pixel electrode 102 on a side different from the side close to the alignment film 151. It is also preferable to arrange the second partial reflector 160 in the vicinity of the counter electrode 103. The second partial reflector 160 in FIG. 4 represents an example in which it is arranged between the counter electrode 103 and the alignment film 153.

[0038] 5A and 5B are diagrams illustrating an example of the configuration of the first partial reflector 130 according to the first embodiment of the present disclosure.

[0039] 5A shows an example of a first partial reflector 130 formed of a wire grid. The first partial reflector 130 in the figure includes a plurality of strip conductors 331. The strip conductors 331 can be made of metal. Air gaps 332 are arranged between the strip conductors. Light vibrating in a direction perpendicular to the strip conductors 331 passes through the wire grid. On the other hand, light vibrating in a direction parallel to the strip conductors 331 is reflected by the wire grid.

[0040] 5B shows an example of a first partial reflector 130 made of a polarizer formed by stacking birefringent materials. The first partial reflector 130 in the figure is made by stacking a dichroic polarizer 333 and a reflective polarizer 334. The first partial reflector 130 in the figure exhibits high reflectivity for light of a first polarization from the reflective polarizer 334 side and high transmittance for light of a second polarization perpendicular to the first polarization. The first partial reflector 130 in the figure also exhibits high absorption for light of the first polarization from the dichroic polarizer 333 side and high transmittance for light of the second polarization perpendicular to the first polarization.

[0041] [Configuration of Second Partial Reflector] FIG. 6 is a diagram illustrating an example configuration of a second partial reflector according to the first embodiment of the present disclosure. This diagram illustrates an example configuration of a reflective holographic element 162 included in the second partial reflector 160. The reflective holographic element 162 in this diagram includes an alignment film 341 and a liquid crystal layer 342. The alignment film 341 aligns liquid crystal molecules in the liquid crystal layer 342. The liquid crystal layer 342 is made of cholesteric liquid crystal and selectively transmits and reflects circularly polarized light. The dotted arrows in the liquid crystal layer 342 in this diagram represent the alignment of the liquid crystal molecules. As shown in this diagram, the liquid crystal molecules in the liquid crystal layer 342 are helically oriented. Circularly polarized light 349 with the same helical winding direction is reflected by the liquid crystal layer 342. Circularly polarized light 348 with a winding direction different from the helical winding direction is transmitted through the liquid crystal layer 342.

[0042] 7A and 7B are diagrams showing other exemplary configurations of the second partial reflector according to the first embodiment of the present disclosure. Fig. 7A is a diagram showing another exemplary configuration of the reflective holographic element 162 of the second partial reflector 160. The reflective holographic element 162 in the same figure includes a liquid crystal layer 343. Note that an alignment film is not shown. The liquid crystal layer 343 is made of cholesteric liquid crystal. The liquid crystal molecules 344 of this liquid crystal layer 343 are helically aligned and the alignment direction is patterned. The reflective surface can be tilted by shifting the alignment direction of the liquid crystal molecules of the liquid crystal layer 343. This allows reflected light to be focused.

[0043] 7B shows an example of focusing incident light using the reflective holographic element 162 of FIG. 7A. The arrows in the figure indicate the trajectory of the incident light. The incident light that passes through the first partial reflector 130 is reflected and focused by the reflective holographic element 162, and is further reflected by the first partial reflector 130. This reflected light is emitted from the optical phase modulation element 10 in a focused state. This makes it possible to improve light utilization efficiency.

[0044] [Method of Manufacturing Optical Phase Modulation Element] Figures 8A to 8H are diagrams showing an example of a method of manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. Figures 8A to 8H show an example of a manufacturing process for the first partial reflector 130 and the pixel electrode 102 of the optical phase modulation element 10. Note that Figures 8A to 8H are based on the assumption that the optical phase modulation element 10 includes the first partial reflector 130 configured by the wire grid described in Figure 5A.

[0045] First, a wiring region 120 is formed on the first substrate 110 (FIG. 8A). The wiring region 120 includes wiring 122, a light-shielding layer 124, and an organic semiconductor layer 123 (not shown).

[0046] Next, a metal film 401, which will be the material of the first partial reflector 130, is laminated on the wiring region 120 (FIG. 8B).

[0047] Next, a resist 402 is formed on the metal film 401. An opening 403 is formed in the resist 402 (FIG. 8C).

[0048] Next, etching is performed using the resist 402 as a mask to form the first partial reflector 130. Next, the resist 402 is removed (FIG. 8D).

[0049] Next, the protective film 141 is disposed. This protective film 141 is configured in a shape that closes the gap 332 of the first partial reflector 130 (FIG. 8E).

[0050] Next, a resist 404 is placed on the protective film 141. An opening 405 is placed in the resist 404 in the area near the light-shielding layer 124 (FIG. 8F).

[0051] Next, the protective film 141 and the interlayer insulating film 121 in the wiring region 120 are etched using the resist 404 as a mask to form an opening 406. Next, the resist 404 is removed (FIG. 8G).

[0052] Next, the pixel electrode 102 is formed (FIG. 8H). At this time, the pixel electrode 102 and the light-shielding layer 124 are connected in the opening 406.

[0053] Through the above steps, the first partial reflector 130 and the pixel electrode 102 can be manufactured.

[0054] 9A to 9F are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. Figures 9A to 9F illustrate an example of a manufacturing process for the counter electrode 103 and the second partial reflector 160 of the optical phase modulation element 10. Note that Figures 9A to 9F are based on the assumption that the optical phase modulation element 10 includes the second partial reflector 160 described in FIG. 6 .

[0055] First, the counter electrode 103 is formed on the second substrate 170 (FIG. 9A). Next, an alignment film 341 is formed on the counter electrode 103 (FIG. 9B). Next, a liquid crystal layer 342 made of cholesteric liquid crystal is formed and hardened. This forms the quarter-wave plate 161 (FIG. 9C).

[0056] Next, an alignment film 345 is formed on the upper layer of the quarter-wave plate 161 (FIG. 9D). Next, a liquid crystal layer 346 of cholesteric liquid crystal is formed and hardened (FIG. 9E). The formation of this alignment film 345 and liquid crystal layer 346 is repeated as necessary. This forms the second partial reflector 160 (FIG. 9F).

[0057] Through the above steps, the counter electrode 103 and the second partial reflector 160 can be manufactured.

[0058] [Another Configuration of Optical Phase Modulation Element] Fig. 10 is a diagram showing another configuration example of the optical phase modulation element according to the first embodiment of the present disclosure. Similar to Fig. 3, this figure is a schematic diagram showing another configuration example of the optical phase modulation element 10. The optical phase modulation element 10 in this figure differs from the optical phase modulation element 10 in Fig. 3 in that it includes a first partial reflector 131 instead of the first partial reflector 130.

[0059] The first partial reflector 131 is configured by a half mirror. Incident light 301 is partially reflected by the first partial reflector 131. Light 307 in FIG. 10 represents this reflected light. Also, part of light 304 from the second partial reflector 160 is transmitted through the first partial reflector 131. Light 308 in FIG. 10 represents this transmitted light.

[0060] As described above, the optical phase modulation element 10 according to the first embodiment of the present disclosure reflects incident light by the first partial reflector 130 and the second partial reflector 160, and passes it through the liquid crystal layer 152. This improves the efficiency of phase modulation without increasing the thickness of the liquid crystal layer 152, and reduces disclination. The vertical drive unit 13 (corresponding to a control circuit) of the optical phase modulation element 10 does not require a special function such as generating a control voltage. Therefore, the optical phase modulation element 10 can reduce disclination while using a control circuit with a simple configuration.

[0061] (2. Second Embodiment) The optical phase modulation element 10 of the first embodiment described above includes the first partial reflector 130 and the second partial reflector 160. In contrast, the optical phase modulation element 10 of the second embodiment of the present disclosure differs from the first embodiment described above in that it further includes a quarter-wave plate and a polarizing plate.

[0062] [Configuration of Optical Phase Modulation Element] Fig. 11 is a diagram showing a configuration example of an optical phase modulation element according to a second embodiment of the present disclosure. Similar to Fig. 3, Fig. 11 is a schematic diagram showing a configuration example of an optical phase modulation element 10. The optical phase modulation element 10 in Fig. 11 differs from the optical phase modulation element 10 in Fig. 3 in that it further includes a quarter-wave plate 181 and a polarizing plate 182.

[0063] The quarter-wave plate 181 converts the light 310 (zero-order light) transmitted through the reflective holographic element 162 into linearly polarized light 311. The polarizing plate 182 blocks the light 311 from the quarter-wave plate 181.

[0064] The light 306 transmitted through the reflective holographic element 162 is converted into light 309 by the quarter-wave plate 181, and is output after passing through the polarizing plate 182.

[0065] The configuration of the optical phase modulation element 10 other than that described above is the same as the configuration of the optical phase modulation element 10 in the first embodiment of the present disclosure, and therefore a description thereof will be omitted.

[0066] As described above, the optical phase modulation element 10 according to the second embodiment of the present disclosure includes the quarter-wave plate 181 and the polarizing plate 182, and can prevent the emission of light that could not be diffracted by the reflective holographic element 162. This can reduce unnecessary light.

[0067] 3. Third Embodiment Variations of the optical phase modulation element 10 will be described.

[0068] [Configuration of Optical Phase Modulation Element] Fig. 12 is a diagram showing a configuration example of an optical phase modulation element according to a third embodiment of the present disclosure. Similar to Fig. 4, Fig. 12 is a schematic cross-sectional view showing a configuration example of an optical phase modulation element 10. Similar to Fig. 4, Fig. 12 shows a pixel 100 portion of a pixel array section 11. The optical phase modulation element 10 in Fig. 12 differs from the optical phase modulation element 10 in Fig. 4 in that the protective film 141 is omitted and a first partial reflector 130 is disposed between the first substrate 110 and the wiring region 120.

[0069] 13 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. Similar to FIG. 4, this figure is a schematic cross-sectional view showing a configuration example of an optical phase modulation element 10. The optical phase modulation element 10 in this figure differs from the optical phase modulation element 10 in FIG. 4 in that the protective film 141 is omitted and the first partial reflector 130 is disposed outside the first substrate 110.

[0070] 14 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. Similar to FIG. 4, this figure is a schematic cross-sectional view showing a configuration example of an optical phase modulation element 10. The optical phase modulation element 10 in this figure differs from the optical phase modulation element 10 in FIG. 4 in that the second partial reflector 160 is disposed outside the second substrate 170.

[0071] 15 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. Similar to FIG. 4 , this figure is a schematic cross-sectional view showing a configuration example of an optical phase modulation element 10. The optical phase modulation element 10 in this figure differs from the optical phase modulation element 10 in FIG. 4 in that the protective film 141 is omitted, the first partial reflector 130 is disposed between the first substrate 110 and the wiring region 120, and the second partial reflector 160 is disposed outside the second substrate 170.

[0072] 16 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. Similar to FIG. 4 , this figure is a schematic cross-sectional view showing a configuration example of an optical phase modulation element 10. The optical phase modulation element 10 in this figure differs from the optical phase modulation element 10 in FIG. 4 in that the protective film 141 is omitted, the first partial reflector 130 is disposed on the outer side of the first substrate 110, and the second partial reflector 160 is disposed on the outer side of the second substrate 170.

[0073] 17 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. Similar to FIG. 3, this diagram is a schematic diagram showing a configuration example of an optical phase modulation element 10. The optical phase modulation element 10 in this diagram differs from the optical phase modulation element 10 in FIG. 3 in that the optical path is reversed.

[0074] Circularly polarized incident light 313 passes through reflective holographic element 162 of second partial reflector 160, is converted by quarter-wave plate 161 into linearly polarized light 314, and is incident on first partial reflector 130. This light 314 is reflected by first partial reflector 130 to become light 315, is converted by quarter-wave plate 161 into circularly polarized light 316, and is incident on reflective holographic element 162. This light 316 is reflected by reflective holographic element 162 to become light 317, is converted by quarter-wave plate 161 into linearly polarized light 318, and is transmitted through first partial reflector 130 to be emitted.

[0075] 18 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. Similar to FIG. 4 , this figure is a schematic cross-sectional view showing a configuration example of an optical phase modulation element 10. The optical phase modulation element 10 in this figure is a specific embodiment of the optical phase modulation element 10 described in FIG. 17 . The optical phase modulation element 10 in this figure differs from the optical phase modulation element 10 in FIG. 4 in that the protective film 141 is omitted, the first partial reflector 130 is disposed between the second substrate 170 and the counter electrode 103, and the second partial reflector 160 is disposed between the alignment film 151 and the pixel electrode 102.

[0076] 18 shows an example in which the first partial reflector 130 is disposed adjacent to a side of the counter electrode 103 different from the side adjacent to the alignment film 153. In addition, the second partial reflector 160 in FIG. 18 shows an example in which the second partial reflector 160 is disposed between the pixel electrode 102 and the alignment film 151.

[0077] 19 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. Similar to FIG. 18 , this figure is a schematic cross-sectional view showing a configuration example of an optical phase modulation element 10. The optical phase modulation element 10 in this figure differs from the optical phase modulation element 10 in FIG. 18 in that the first partial reflector 130 is disposed on the outer side of the second substrate 170 and the second partial reflector 160 is disposed on the outer side of the first substrate 110.

[0078] 20 is a diagram showing another configuration example of an optical phase modulation element according to the third embodiment of the present disclosure. Similar to FIG. 18 , this figure is a schematic cross-sectional view showing a configuration example of an optical phase modulation element 10. The optical phase modulation element 10 in this figure differs from the optical phase modulation element 10 in FIG. 18 in that the second partial reflector 160 is disposed outside the first substrate 110.

[0079] The configuration of the optical phase modulation element 10 other than that described above is the same as the configuration of the optical phase modulation element 10 in the first embodiment of the present disclosure, and therefore a description thereof will be omitted.

[0080] (4. Configuration of Display Device) A display device including the above-described optical phase modulation element 10 will be described.

[0081] 21 is a diagram showing a configuration example of a display device according to an embodiment of the present disclosure. The figure is a block diagram showing a configuration example of a display device 1. This display device 1 is a display device that displays holograms and the like. The display device 1 includes a light source 20, an optical phase modulation element 10, and a control unit 30.

[0082] The light source 20 generates light incident on the optical phase modulation element 10. For example, a laser light source can be used as the light source 20.

[0083] The control unit 30 controls the entire display device 1. The control unit 30 generates and outputs a signal for the horizontal drive unit 12 of the optical phase modulation element 10 based on an image signal input from the outside. The control unit 30 also controls the light emission of the light source 20.

[0084] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0085] Note that the present technology can also be configured as follows: (1) A liquid crystal display device comprising: a pixel including a liquid crystal layer that adjusts the phase of incident light, a pixel electrode and a counter electrode that are arranged across the liquid crystal layer and that apply a voltage to the liquid crystal layer, a first alignment film that is arranged adjacent to a surface of the liquid crystal layer that is close to the pixel electrode, and a second alignment film that is arranged adjacent to a surface of the liquid crystal layer that is close to the counter electrode, a first substrate that is provided with a pixel circuit that drives the pixel and that supports the pixel electrode and the first alignment film, a second substrate that supports the counter electrode and the second alignment film, and a first partial reflector and a second partial reflector that are arranged across the first alignment film, the liquid crystal layer, and the second alignment film and that transmit a portion of the incident light and reflect a portion of the incident light, wherein the first partial reflector transmits at least a portion of the incident light from a light source to make it incident on the second partial reflector and reflects at least a portion of the light reflected by the second partial reflector to make it incident again on the second partial reflector; An optical phase modulation element, wherein the second partial reflector reflects at least a portion of the light transmitted through the first partial reflector to be incident again on the first partial reflector and transmits at least a portion of the light reflected by the first partial reflector. (2) The optical phase modulation element described in (1), wherein the first partial reflector emits reflected light having the same polarization direction as the incident light, and the second partial reflector emits reflected light having a polarization direction different from that of the incident light. (3) The optical phase modulation element described in (2), wherein the second partial reflector comprises a quarter-wave plate that converts the polarization state of the incident light between linearly polarized light and circularly polarized light, and a reflective holographic element that reflects one of the incident lights having circularly polarized light with a different rotation direction and transmits the other. (4) The optical phase modulation element described in (3), wherein the reflective holographic element includes a cholesteric liquid crystal. (5) The optical phase modulation element described in (2), wherein the first partial reflector is composed of a reflective polarizing plate that reflects one of the incident lights having linearly polarized light with a different polarization direction and transmits the other. (6) The optical phase modulation element according to (1), wherein the first partial reflector is a half mirror.(7) The optical phase modulation element according to any one of (1) to (6), wherein the first partial reflector is disposed adjacent to either a side of the pixel electrode different from a side close to the first alignment film or a side of the counter electrode different from a side close to the second alignment film. (8) The optical phase modulation element according to any one of (1) to (6), wherein the second partial reflector is disposed either between the pixel electrode and the first alignment film or between the counter electrode and the second alignment film. (9) The optical phase modulation element according to any one of (1) to (8), further comprising: a quarter-wave plate that converts light transmitted through the second partial reflector into linearly polarized light; and a polarizing plate that transmits light of a predetermined polarization direction out of the linearly polarized light transmitted through the quarter-wave plate. (10) A liquid crystal display device comprising: a pixel including a liquid crystal layer that adjusts the phase of incident light; a pixel electrode and a counter electrode that are arranged across the liquid crystal layer and that apply a voltage to the liquid crystal layer; a first alignment film that is arranged adjacent to the surface of the liquid crystal layer that is close to the pixel electrode; and a second alignment film that is arranged adjacent to the surface of the liquid crystal layer that is close to the counter electrode; a first substrate that is provided with a pixel circuit that drives the pixel and that supports the pixel electrode and the first alignment film; a second substrate that supports the counter electrode and the second alignment film; and a first partial reflector and a second partial reflector that are arranged across the first alignment film, the liquid crystal layer, and the second alignment film and that transmit a part of the incident light and reflect a part of the incident light, wherein the first partial reflector transmits at least a part of the incident light from a light source to make it incident on the second partial reflector and reflects at least a part of the light reflected by the second partial reflector to make it incident again on the second partial reflector; a second partial reflector that reflects at least a portion of the light that has passed through the first partial reflector to make it incident on the first partial reflector again and that transmits at least a portion of the light that has been reflected by the first partial reflector; and a light source that generates the incident light.

[0086] REFERENCE SIGNS LIST 1 display device 10 optical phase modulation element 20 light source 100, 100a, 100b pixel 101 MOS transistor 102 pixel electrode 103 counter electrode 110 first substrate 130, 131 first partial reflector 151, 153 alignment film 152 liquid crystal layer 160 second partial reflector 161, 181 quarter-wave plate 162 reflective holographic element 170 second substrate 182 polarizer

Claims

1. A liquid crystal display device comprising: a pixel including a liquid crystal layer that adjusts the phase of incident light; a pixel electrode and a counter electrode that are arranged across the liquid crystal layer and that apply a voltage to the liquid crystal layer; a first alignment film that is arranged adjacent to the surface of the liquid crystal layer that is close to the pixel electrode; and a second alignment film that is arranged adjacent to the surface of the liquid crystal layer that is close to the counter electrode; a first substrate that is provided with a pixel circuit that drives the pixel and that supports the pixel electrode and the first alignment film; a second substrate that supports the counter electrode and the second alignment film; and a first partial reflector and a second partial reflector that are arranged across the first alignment film, the liquid crystal layer, and the second alignment film and that transmit a portion of the incident light and reflect a portion of the incident light, wherein the first partial reflector transmits at least a portion of the incident light from a light source to make it incident on the second partial reflector and reflects at least a portion of the light reflected by the second partial reflector to make it incident again on the second partial reflector; The second partial reflector reflects at least a portion of the light that has passed through the first partial reflector to make it re-enter the first partial reflector, and transmits at least a portion of the light that has been reflected by the first partial reflector.

2. The optical phase modulation element according to claim 1, wherein the first partial reflector emits reflected light having the same polarization direction as the incident light, and the second partial reflector emits reflected light having a polarization direction different from that of the incident light.

3. The optical phase modulation element according to claim 2, wherein the second partial reflector comprises a quarter-wave plate that converts the polarization state of incident light between linearly polarized light and circularly polarized light, and a reflective holographic element that reflects one of the incident lights with circularly polarized light in a different rotation direction and transmits the other.

4. The optical phase modulation element according to claim 3, wherein said reflective holographic element comprises a cholesteric liquid crystal.

5. The optical phase modulation element according to claim 2, wherein the first partial reflector is a reflective polarizing plate that reflects one of the incident light beams having different polarization directions of linear polarization and transmits the other.

6. The optical phase modulation element according to claim 1, wherein the first partial reflector is a half mirror.

7. An optical phase modulation element as described in claim 1, wherein the first partial reflector is positioned adjacent to either a side of the pixel electrode other than the side adjacent to the first alignment film or a side of the opposing electrode other than the side adjacent to the second alignment film.

8. The optical phase modulation element according to claim 1, wherein the second partial reflector is disposed either between the pixel electrode and the first alignment film or between the counter electrode and the second alignment film.

9. The optical phase modulation element according to claim 1, further comprising: a quarter-wave plate that converts the light that has passed through the second partial reflector into linearly polarized light; and a polarizing plate that transmits light of a predetermined polarization direction from the linearly polarized light that has passed through the quarter-wave plate.

10. A liquid crystal display device comprising: a pixel including a liquid crystal layer that adjusts the phase of incident light; a pixel electrode and a counter electrode that are arranged across the liquid crystal layer and that apply a voltage to the liquid crystal layer; a first alignment film that is arranged adjacent to the surface of the liquid crystal layer that is close to the pixel electrode; and a second alignment film that is arranged adjacent to the surface of the liquid crystal layer that is close to the counter electrode; a first substrate that is provided with a pixel circuit that drives the pixel and that supports the pixel electrode and the first alignment film; a second substrate that supports the counter electrode and the second alignment film; and a first partial reflector and a second partial reflector that are arranged across the first alignment film, the liquid crystal layer, and the second alignment film and that transmit a portion of the incident light and reflect a portion of the incident light, wherein the first partial reflector transmits at least a portion of the incident light from a light source to make it incident on the second partial reflector and reflects at least a portion of the light reflected by the second partial reflector to make it incident again on the second partial reflector; a second partial reflector that reflects at least a portion of the light that has passed through the first partial reflector to make it incident on the first partial reflector again and that transmits at least a portion of the light that has been reflected by the first partial reflector; and a light source that generates the incident light.

Images