WO2025205204A1 - Optical phase modulation element and display device - Google Patents

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

This disclosure relates to an optical phase modulation element and a display device.

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 type of inter-pixel crosstalk, also known as disclination, causes a decrease in image quality.

Liquid crystal panels that prevent this type of disclination have been proposed. For example, a liquid crystal panel (light modulation panel) has been proposed in which control electrodes are provided between pixels, and an electric field different from the electric field between the electrodes is formed to control the alignment direction of the liquid crystal (see, for example, Patent Document 1).

JP 2014-137581 A

However, the above-mentioned conventional technology requires a circuit to supply a control voltage to the control electrode, which makes the control circuit complex.

This disclosure therefore proposes an optical phase modulation element that reduces disclination using a control circuit with a simple configuration, and a display device that uses this optical phase modulation element.

The optical phase modulation element of the present disclosure comprises a pixel having 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 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 closest to the pixel electrode, and a second alignment film that is arranged adjacent to the surface of the liquid crystal layer that is closest to the counter electrode, a pixel circuit that drives the pixel and 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 the incident light and reflect a portion of the incident light, and the first partial reflector transmits at least a portion of the incident light from the 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 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.

1 is a diagram illustrating a configuration example of an optical phase modulation element according to a first embodiment of the present disclosure. 1A and 1B are diagrams illustrating an optical phase modulation element according to an embodiment of the present disclosure. 1A and 1B are diagrams illustrating an optical phase modulation element according to an embodiment of the present disclosure. 1A and 1B are diagrams illustrating an optical phase modulation element according to an embodiment of the present disclosure. 1 is a diagram illustrating a configuration example of an optical phase modulation element according to a first embodiment of the present disclosure. 1 is a diagram illustrating a configuration example of an optical phase modulation element according to a first embodiment of the present disclosure. 3A and 3B are diagrams illustrating a configuration example of a first partial reflector according to the first embodiment of the present disclosure. 3A and 3B are diagrams illustrating a configuration example of a first partial reflector according to the first embodiment of the present disclosure. FIG. 4 is a diagram illustrating a configuration example of a second partial reflector according to the first embodiment of the present disclosure. 10A and 10B are diagrams illustrating another configuration example of the second partial reflector according to the first embodiment of the present disclosure. 10A and 10B are diagrams illustrating another configuration example of the second partial reflector according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. 3A to 3C are diagrams illustrating an example of a method for manufacturing an optical phase modulation element according to the first embodiment of the present disclosure. FIG. 4 is a diagram illustrating another configuration example of the optical phase modulation element according to the first embodiment of the present disclosure. FIG. 10 is a diagram illustrating a configuration example of an optical phase modulation element according to a second embodiment of the present disclosure. FIG. 10 is a diagram illustrating a configuration example of an optical phase modulation element according to a third embodiment of the present disclosure. FIG. 10 is a diagram illustrating another configuration example of the optical phase modulation element according to the third embodiment of the present disclosure. FIG. 10 is a diagram illustrating another configuration example of the optical phase modulation element according to the third embodiment of the present disclosure. FIG. 10 is a diagram illustrating another configuration example of the optical phase modulation element according to the third embodiment of the present disclosure. FIG. 10 is a diagram illustrating another configuration example of the optical phase modulation element according to the third embodiment of the present disclosure. FIG. 10 is a diagram illustrating another configuration example of the optical phase modulation element according to the third embodiment of the present disclosure. FIG. 10 is a diagram illustrating another configuration example of the optical phase modulation element according to the third embodiment of the present disclosure. FIG. 10 is a diagram illustrating another configuration example of the optical phase modulation element according to the third embodiment of the present disclosure. FIG. 10 is a diagram illustrating another configuration example of the optical phase modulation element according to the third embodiment of the present disclosure. FIG. 1 is a diagram illustrating a configuration example of a display device according to an embodiment of the present disclosure.

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. 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

(1. First embodiment)
[Configuration of optical phase modulation element]
1 is a diagram showing an example of the configuration of an optical phase modulation element according to a first embodiment of the present disclosure. The figure is a block diagram showing an example of the configuration 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.

The pixel array section 11 is configured with an arrangement of multiple pixels 100. The pixel array section 11 in Figure 1 shows an example in which multiple pixels 100 are arranged in a two-dimensional matrix. Here, the pixel 100 comprises 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 according to an input signal. The drive voltage is applied via a pixel electrode (pixel electrode 102) and a counter electrode (counter electrode 103) that are configured to sandwich the liquid crystal layer. Figure 1 shows the pixel electrode 102. The pixel circuit is also configured with a MOS transistor 101. The source of this MOS transistor 101 is connected to the pixel electrode 102.

Signal lines 14 and data lines 15 are wired to each pixel 100. The signal lines 14 transmit control signals for the pixel circuit. 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 multiple pixels 100 arranged in a single row. The data lines 15 are arranged in columns in a two-dimensional matrix, and are wired in common to multiple pixels 100 arranged in a single column.

The vertical drive unit 13 generates control signals for the pixels 100 described above. The vertical drive unit 13 in Figure 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.

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

[Outline of optical phase modulation element]
2A-2C are diagrams illustrating an optical phase modulation element according to an embodiment of the present disclosure. FIG. 2A is a diagram illustrating an overview 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.

The left side of Figure 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, allowing for a large amount of phase change. This makes it possible to reduce the thickness d of the liquid crystal layer 152. However, reflective optical phase modulation elements have the problem of making the optical system complex.

The right side of Figure 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 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 poses the problem of a decrease in response speed and an increase in disclination.

Figure 2B is a diagram explaining disclination. The optical phase modulation element in this figure further illustrates the counter electrode 103 and pixel electrode 102, and neighboring pixels 100a and 100b. The counter electrode 103 is disposed in common to pixels 100a and 100b. Meanwhile, as described above, the pixel electrode 102 is disposed for each pixel 100. This figure illustrates the case where different voltages are applied to the pixel electrodes 102 of pixels 100a and 100b. The arrows in pixel 100a in this figure represent the electric field. As shown in this figure, the electric field bends toward pixel 100b at the end of pixel 100a, causing the alignment of the liquid crystal molecules 154 to become distorted. This disruption in the alignment of the liquid crystal molecules 154 causes disclination.

Figure 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 where no disclination occurs. In contrast, the dotted line graph in the figure represents a case where disclination occurs. It can be seen that disclination reduces the amount of phase change.

The optical phase modulation element disclosed herein can improve the amount of phase modulation while preventing an increase in the thickness of the liquid crystal layer 152.

[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 shown in this figure 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 this figure represent incident light from a light source.

The first partial reflector 130 transmits at least a portion of the incident light from the light source, causing it to be incident on the second partial reflector 160, and reflects at least a portion of the light reflected by the second partial reflector 160, causing it to be incident again on the second partial reflector 160. At this time, the first partial reflector 130 emits reflected light with the same polarization direction as the incident light. The second partial reflector 160 also reflects at least a portion of the light that has transmitted through the first partial reflector 130, causing it to be incident again 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 with a polarization direction different from that of the incident light.

The first partial reflector 130 can be configured as a reflective polarizing plate that reflects one of the incident light beams with 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 between linear polarization and circular polarization. The reflective holographic element 162 reflects one of the incident light beams with different circular polarization directions and transmits the other.

Incoming light 301 is assumed to be linearly polarized light. The thick arrows in Figure 3 indicate the polarization direction. As shown in Figure 3, incoming light 301 is light with an upward polarization direction in Figure 3. This incoming 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 incoming light 301 into circularly polarized light 302. As shown in Figure 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, becoming light 303, which enters the quarter-wave plate 161.

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

In this way, 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, allowing phase modulation by the liquid crystal layer 152 to occur.

FIG. 4 is a diagram showing an example configuration of an optical phase modulation element according to the first embodiment of the present disclosure. The figure is a schematic cross-sectional view showing an example configuration of an optical phase modulation element 10. The optical phase modulation element 10 in the figure is a concrete example of the optical phase modulation element 10 described in FIG. 3. The figure shows a pixel 100 portion of the 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.

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

The wiring region 120 is a region where wiring and the like of the pixel 100 are formed. This wiring region 120 includes an interlayer insulating film 121 and wiring 122. The interlayer insulating film 121 can be 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 also 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.

As described above, the first partial reflector 130 transmits at least a portion of the incident light from the light source and makes it incident on the second partial reflector 160, and reflects at least a portion of the light reflected by the second partial reflector 160 and makes it incident again on the second partial reflector 160. Details of the configuration of the first partial reflector 130 will be described later.

The protective film 141 is laminated on the first partial reflector 130 to protect the first partial reflector 130. This protective film 141 can be made of, for example, SiO ₂ .

As mentioned above, the pixel electrode 102 is an electrode that is arranged for each pixel 100 and applies a voltage to the liquid crystal layer 152. This pixel electrode 102 can be made of, for example, ITO (Indium Tin Oxide). A light-shielding portion 142 is arranged around the pixel electrode 102. This light-shielding portion 142 forms a black matrix.

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

As mentioned above, the second partial reflector 160 reflects at least a portion of the light that has passed through the first partial reflector 130, causing it to re-enter the first partial reflector 130, and also transmits at least a portion of the light reflected by the first partial reflector 130. As mentioned 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 for the quarter-wave plate 161. The configuration of the reflective holographic element 162 will be described in detail below.

The counter electrode 103 is an electrode that is disposed in common to multiple pixels 100 and applies a voltage to the liquid crystal layer 152 of each pixel 100. This counter electrode 103 can be made of ITO. As shown in Figure 4, the pixel electrode 102 and counter electrode 103 are disposed with the liquid crystal layer 152 sandwiched between them.

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

It is preferable to position the first partial reflector 130 and the second partial reflector 160 close to the liquid crystal layer 152. The first partial reflector 130 is preferably positioned close to the pixel electrode 102. The first partial reflector 130 in Figure 4 represents an example in which it is positioned close to a side of the pixel electrode 102 different from the side close to the alignment film 151. The second partial reflector 160 is preferably positioned close to the counter electrode 103. The second partial reflector 160 in Figure 4 represents an example in which it is positioned between the counter electrode 103 and the alignment film 153.

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

Figure 5A shows an example of a first partial reflector 130 made of a wire grid. The first partial reflector 130 in this figure has a plurality of strip conductors 331. These 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.

Figure 5B shows an example of a first partial reflector 130 made up of a polarizer formed by stacking materials having birefringence. The first partial reflector 130 in the figure is made up of a dichroic polarizer 333 and a reflective polarizer 334 stacked together. 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 a second polarization perpendicular to the first polarization.

[Configuration of the second partial reflector]
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.

Figures 7A and 7B are diagrams showing other exemplary configurations of the second partial reflector according to the first embodiment of the present disclosure. Figure 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 the 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 in the liquid crystal layer 343. This makes it possible to focus the reflected light.

Figure 7B shows an example of focusing incident light using the reflective holographic element 162 of Figure 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 can improve the light utilization efficiency.

[Method of manufacturing optical phase modulation element]
8A to 8H are diagrams showing an example of a manufacturing method of the 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. It should be noted 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.

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

Next, a metal film 401, which will be the material for the first partial reflector 130, is laminated on the wiring area 120 (Figure 8B).

Next, a resist 402 is formed on top of the metal film 401. An opening 403 is formed in this resist 402 (Figure 8C).

Next, etching is performed using the resist 402 as a mask to form the first partial reflector 130. The resist 402 is then removed (Figure 8D).

Next, the protective film 141 is placed. This protective film 141 is configured in a shape that closes the gap 332 in the first partial reflector 130 (Figure 8E).

Next, a resist 404 is placed on top of the protective film 141. An opening 405 is placed in this resist 404 in the area near the light-shielding layer 124 (Figure 8F).

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. The resist 404 is then removed (Figure 8G).

Next, the pixel electrode 102 is formed (Figure 8H). At this time, the pixel electrode 102 and the light-shielding layer 124 are connected at the opening 406.

The above steps allow the first partial reflector 130 and pixel electrode 102 to be manufactured.

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

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

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

The counter electrode 103 and second partial reflector 160 can be manufactured through the above steps.

[Other configurations of optical phase modulation element]
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.

The first partial reflector 131 is composed of a half mirror. The incident light 301 is partially reflected by the first partial reflector 131. Light 307 in Figure 10 represents this reflected light. Furthermore, part of the light 304 from the second partial reflector 160 is transmitted through the first partial reflector 131. Light 308 in Figure 10 represents this transmitted light.

In this way, the optical phase modulation element 10 of the first embodiment of the present disclosure uses the first partial reflector 130 and the second partial reflector 160 to reflect incident light and pass 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 special functions 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.

(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.

[Configuration of optical phase modulation element]
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, 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 it further includes a quarter-wave plate 181 and a polarizing plate 182.

The quarter-wave plate 181 converts the light 310 (zero-order light) that has passed 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.

In addition, light 306 that passes 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.

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, so further description will be omitted.

In this way, the optical phase modulation element 10 of the second embodiment of the present disclosure includes a quarter-wave plate 181 and a polarizing plate 182, and can prevent the emission of light that could not be diffracted by the reflective holographic element 162. This makes it possible to reduce unnecessary light.

(3. Third embodiment)
Variations of the optical phase modulation element 10 will be described.

[Configuration of optical phase modulation element]
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 , this figure is a schematic cross-sectional view showing a configuration example of an optical phase modulation element 10. Similar to FIG. 4 , this figure shows the pixel 100 portion of the pixel array section 11. 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 a first partial reflector 130 is disposed between the first substrate 110 and the wiring region 120.

FIG. 13 is a diagram showing another example configuration 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 an example configuration 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 positioned outside the first substrate 110.

FIG. 14 is a diagram showing another example configuration 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 an example configuration 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.

FIG. 15 is a diagram showing another example configuration 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 an example configuration 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.

FIG. 16 is a diagram showing another example configuration 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 an example configuration 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 outside of the first substrate 110, and the second partial reflector 160 is disposed on the outside of the second substrate 170.

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

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 enters 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 enters 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 passes through first partial reflector 130 to be emitted.

FIG. 18 is a diagram showing another example configuration 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 an example configuration of an optical phase modulation element 10. The optical phase modulation element 10 in this figure is a concrete 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.

The first partial reflector 130 in Figure 18 shows an example in which it is placed close to the opposing electrode 103 on a side different from the side close to the alignment film 153. The second partial reflector 160 in Figure 18 shows an example in which it is placed between the pixel electrode 102 and the alignment film 151.

FIG. 19 is a diagram showing another example configuration 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 an example configuration 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 arranged on the outside of the second substrate 170, and the second partial reflector 160 is arranged on the outside of the first substrate 110.

FIG. 20 is a diagram showing another example configuration 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 an example configuration 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.

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, so further description will be omitted.

(4. Configuration of the display device)
A display device including the above-described optical phase modulation element 10 will now be described.

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

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

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.

Please note that the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

The present technology can also be configured as follows.
(1)
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 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 including a pixel circuit for driving the pixel and supporting the pixel electrode and the first alignment film;
a second substrate supporting the counter electrode and the second alignment film;
a first partial reflector and a second partial reflector that are arranged with the first alignment film, the liquid crystal layer, and the second alignment film sandwiched therebetween and transmit a part of incident light and reflect a part of the incident light,
the first partial reflector transmits at least a portion of the incident light from the 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 on the second partial reflector again;
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 first partial reflector emits reflected light having the same polarization direction as the incident light,
The optical phase modulation element according to (1), wherein 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) above, wherein the second partial reflector comprises a quarter-wave plate that converts the polarization state of incident light into linear polarization and circular polarization, and a reflective holographic element that reflects one of the incident lights having different rotation directions of circular polarization and transmits the other.
(4)
The optical phase modulation element according to (3), wherein the reflective holographic element includes a cholesteric liquid crystal.
(5)
The optical phase modulation element according to (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 (1), wherein the first partial reflector is configured by a half mirror.
(7)
An optical phase modulation element described in any of (1) to (6), wherein the first partial reflector is arranged 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)
An optical phase modulation element described in any of (1) to (6), wherein the second partial reflector is arranged either between the pixel electrode and the first alignment film or between the counter electrode and the second alignment film.
(9)
a quarter-wave plate that converts the light transmitted through the second partial reflector into linearly polarized light;
The optical phase modulation element according to any one of (1) to (8), further comprising: a polarizing plate that transmits light of a predetermined polarization direction out of the linearly polarized light that has passed through the quarter-wave plate.
(10)
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 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 including a pixel circuit for driving the pixel and supporting the pixel electrode and the first alignment film;
a second substrate supporting the counter electrode and the second alignment film;
a first partial reflector and a second partial reflector disposed on opposite sides of the first alignment film, the liquid crystal layer, and the second alignment film, the first partial reflector transmitting a part of incident light and reflecting a part of incident light,
the first partial reflector transmits at least a portion of the incident light from the 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 on the second partial reflector again;
an optical phase modulation element, wherein the second partial reflector reflects at least a part of the light transmitted through the first partial reflector to make the light incident on the first partial reflector again and transmits at least a part of the light reflected by the first partial reflector;
a light source that generates the incident light.

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 (10)

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 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 including a pixel circuit for driving the pixel and supporting the pixel electrode and the first alignment film;
a second substrate supporting the counter electrode and the second alignment film;
a first partial reflector and a second partial reflector that are arranged with the first alignment film, the liquid crystal layer, and the second alignment film sandwiched therebetween and transmit a part of incident light and reflect a part of the incident light,
the first partial reflector transmits at least a portion of the incident light from the 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 on the second partial reflector again;
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. the first partial reflector emits reflected light having the same polarization direction as the incident light,
The optical phase modulation element according to claim 1 , wherein the second partial reflector emits reflected light having a polarization direction different from that of the incident light. The optical phase modulation element described in 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 light beams with different circular polarization directions and transmits the other. The optical phase modulation element described in claim 3, wherein the reflective holographic element is configured to include a cholesteric liquid crystal. The optical phase modulation element described in 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. The optical phase modulation element described in claim 1, wherein the first partial reflector is composed of a half mirror. The optical phase modulation element described in claim 1, wherein the first partial reflector is disposed adjacent to either a side of the pixel electrode other than the side adjacent to the first alignment film or a side of the counter electrode other than the side adjacent to the second alignment film. The optical phase modulation element described in 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. a quarter-wave plate that converts the light transmitted through the second partial reflector into linearly polarized light;
2. The optical phase modulation element according to claim 1, further comprising: a polarizing plate that transmits light of a predetermined polarization direction out of the linearly polarized light that has passed through the quarter-wave plate. 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 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 including a pixel circuit for driving the pixel and supporting the pixel electrode and the first alignment film;
a second substrate supporting the counter electrode and the second alignment film;
a first partial reflector and a second partial reflector disposed on either side of the first alignment film, the liquid crystal layer, and the second alignment film, the first partial reflector transmitting a part of incident light and reflecting a part of incident light;
the first partial reflector transmits at least a portion of the incident light from the 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 on the second partial reflector again;
an optical phase modulation element, wherein the second partial reflector reflects at least a part of the light transmitted through the first partial reflector to make the light incident on the first partial reflector again and transmits at least a part of the light reflected by the first partial reflector;
a light source that generates the incident light.