WO2019208205A1

WO2019208205A1 - Optical phase control device and display device

Info

Publication number: WO2019208205A1
Application number: PCT/JP2019/015457
Authority: WO
Inventors: 佳明神山
Original assignee: ソニーセミコンダクタソリューションズ株式会社
Priority date: 2018-04-26
Filing date: 2019-04-09
Publication date: 2019-10-31
Also published as: CN112005547A; CN112005547B

Abstract

This display device is provided with: a phase distribution computation circuit for generating data of a plurality of phase distributions for each wavelength, the phase distributions corresponding to a reproduced image for each wavelength that is reproduced by an optical phase modulation element; and a drive circuit for generating, on the basis of the data of the plurality of phase distributions for each wavelength, a plurality of applied voltages for each wavelength that are applied to the optical phase modulation element and causing the phases of a plurality of lights mutually differing in wavelength that are entered separately in time to be modulated for each wavelength separately in time by the optical phase modulation element. The drive circuit generates the plurality of applied voltages so that the voltage range differs for each wavelength, and so that the minimum value of the voltage range decreases and the maximum value increases as the wavelength increases.

Description

Optical phase control device and display device

The present disclosure relates to an optical phase control device that controls an optical phase modulation element and a display device that uses the optical phase modulation element.

An optical phase modulation element that obtains a desired reproduced image by modulating the phase of light is known. The optical phase modulation element is composed of an SLM (Spatial Light Modulator) such as a liquid crystal panel. As an application example of such an optical phase modulation element, in a projector, a reproduction image that is phase-modulated according to an image is generated by using the optical phase modulation element in an illumination device, and the reproduction image is used as a light intensity for video display. There is a technique used as illumination light for a modulation element. The optical phase modulation element is also used for holography technology and the like. The optical phase modulation element is also used in technologies such as an optical switch and an optical computer.

Japanese Patent Laying-Open No. 2015-184288 JP-T-2015-505971

When a moving image is displayed using an optical phase modulation element using a liquid crystal, particularly a full-color display by a field sequential method (time division method), a reproduced image may be deteriorated due to a slow response speed of the liquid crystal.

It is desirable to provide an optical phase control device and a display device that can improve the quality of a reproduced image by an optical phase modulation element.

An optical phase control device according to an embodiment of the present disclosure includes a phase distribution arithmetic circuit that generates data of a plurality of phase distributions for each wavelength corresponding to a reproduction image for each wavelength reproduced by an optical phase modulation element, and a wavelength A plurality of applied voltages for each wavelength applied to the optical phase modulation element are generated based on the data of the plurality of phase distributions for each of the plurality of light beams having different wavelengths incident on the optical phase modulation element in a time division manner. A drive circuit that modulates the phase of each wavelength in a time-sharing manner so that the drive circuit has a different voltage range for each wavelength, and the longer the wavelength, the smaller the minimum value of the voltage range and the larger the maximum value. Thus, a plurality of applied voltages are generated.

A display device according to an embodiment of the present disclosure includes a light source that emits a plurality of lights having different wavelengths in a time-division manner, and a phase of the plurality of lights from the light source that is modulated in a time-division manner for each wavelength. Phase distribution calculation that generates multiple phase distribution data for each wavelength corresponding to multiple reproduction images for each wavelength reproduced by the optical phase modulation element Based on the data of the circuit and multiple phase distributions for each wavelength, multiple applied voltages for each wavelength to be applied to the optical phase modulation element are generated, and the phases of the multiple lights for each wavelength are applied to the optical phase modulation element. A drive circuit that modulates in a time-sharing manner, and the drive circuit has different voltage ranges for each wavelength, and the longer the wavelength, the smaller the minimum value of the voltage range and the larger the maximum value. To generate voltage It is intended.

In the optical phase control device or the display device according to the embodiment of the present disclosure, in the driving circuit, a plurality of applied voltages for each wavelength applied to the optical phase modulation element based on data of a plurality of phase distributions for each wavelength. Is generated. In the drive circuit, a plurality of applied voltages are generated such that the voltage range is different for each wavelength and the minimum value of the voltage range is smaller and the maximum value is larger as the wavelength is longer.

It is a block diagram showing an example of 1 composition of a phase modulation device containing an optical phase control device concerning a 1st embodiment of this indication. It is explanatory drawing which shows the outline | summary of an optical phase modulation element. It is a block diagram which shows the 1st structural example of the projector as a display apparatus which concerns on 1st Embodiment. It is a block diagram which shows the 2nd structural example of the projector as a display apparatus which concerns on 1st Embodiment. FIG. 10 is an explanatory diagram illustrating an example of a voltage range of each color necessary for 0 to 2π phase modulation in a display device according to a comparative example. It is explanatory drawing which shows an example of the relationship between the phase modulation amount and applied voltage in the display apparatus which concerns on a comparative example. In the display apparatus which concerns on a comparative example, it is explanatory drawing which shows the case where the same reproduced image is displayed by the optical phase modulation element using different phase distribution. FIG. 6 is an explanatory diagram illustrating an example of a voltage range of each color necessary for phase modulation of 0 to 2π in the display device according to the first embodiment. It is explanatory drawing which shows one Example of the relationship between the phase modulation amount and applied voltage in the display apparatus which concerns on 1st Embodiment. In the display device according to the comparative example and the display device according to the first embodiment, when the same phase is displayed on the optical phase modulation element, the amount of voltage fluctuation caused by the switching of the wavelength between R and G and the frequency thereof It is explanatory drawing which shows an example of a relationship. In the display device according to the comparative example and the display device according to the first embodiment, when the same phase is displayed on the optical phase modulation element, the voltage fluctuation amount generated by the switching of the wavelength between G and B and the frequency thereof It is explanatory drawing which shows an example of a relationship. In the display device according to the comparative example and the display device according to the first embodiment, when the same phase is displayed on the optical phase modulation element, the amount of voltage fluctuation caused by the switching of the wavelength between B and R and the frequency thereof It is explanatory drawing which shows an example of a relationship. FIG. 10 is an explanatory diagram illustrating an example of a voltage range of each color necessary for phase modulation of 0 to about 2π in a display device according to a comparative example. It is explanatory drawing which shows an example of the relationship between the phase modulation amount and applied voltage in the display apparatus which concerns on a comparative example. FIG. 10 is an explanatory diagram showing an example of a voltage range of each color necessary for phase modulation of 0 to about 2π in the display device according to the second embodiment. It is explanatory drawing which shows one Example of the relationship between the phase modulation amount and applied voltage in the display apparatus which concerns on 2nd Embodiment. In the display apparatus which concerns on 2nd Embodiment, when the same phase is displayed, it is explanatory drawing which shows an example of the relationship between the voltage fluctuation amount produced by the switching of the wavelength of R and G, and its frequency. In the display apparatus which concerns on 2nd Embodiment, when the same phase is displayed, it is explanatory drawing which shows an example of the relationship between the voltage fluctuation amount produced by the switching of the wavelength of B and R, and its frequency. It is explanatory drawing which shows the 1st example of the production | generation method of the target phase distribution data in the display apparatus which concerns on 3rd Embodiment. It is explanatory drawing which shows the 2nd example of the production | generation method of the target phase distribution data in the display apparatus which concerns on 3rd Embodiment.

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.

1. First embodiment (FIGS. 1 to 12)
1.0 Comparative Example 1.1 Configuration and Operation of Optical Phase Control Device and Display Device According to First Embodiment 1.2 Effect Second embodiment (FIGS. 13 to 18)
3. Third embodiment (FIGS. 19 to 20)
4). Other embodiments

<1. First Embodiment>
[1.0 Comparative Example]
When a moving image is displayed using an optical phase modulation element using liquid crystal, particularly a full-color display by a field sequential method, a reproduced image can be deteriorated due to a slow response speed of the liquid crystal.

Patent Document 1 (Japanese Patent Laid-Open No. 2015-184288) discloses a technique for generating a phase distribution at a high speed, which can be applied to field sequential driving. However, even if the phase distribution is generated at high speed, the liquid crystal in the optical phase modulation element cannot sufficiently respond to the switching of the phase distribution, so that the reproduced image is deteriorated such as noise generation, luminance reduction, contrast reduction, and flicker. Can occur.

Patent Document 2 (Japanese Patent Publication No. 2015-505971) discloses a high-speed phase distribution generation method based on the Gerchberg-Saxton method (GS method) using Fourier transform. In the technique described in Patent Document 2, the phase distribution is generated at high speed by handing over the phase information of the previous frame to the initial phase information of the next frame. Furthermore, when this method is used, the convergent phase distribution becomes close between frames, and the change in voltage at the pixel is small. Therefore, there is no large change in the tilt of the liquid crystal when the phase distribution is switched, and the degradation of the reproduced image can be suppressed. However, when performing field sequential drive, the phase modulation amount and thus the voltage range of the applied voltage change according to the wavelength to be modulated, so even if the phase distribution can be made closer between frames, the final Since applied voltages differ, it is inevitable that the reproduced image is deteriorated.

Therefore, in this disclosure, when the optical phase modulation element using liquid crystal is field-sequentially driven, the voltage range of the applied voltage of the optical phase modulation element is adjusted for each wavelength to be phase-modulated, and the voltage change of each pixel between frames A technique for improving the quality of a reproduced image by reducing the amount is provided.

[1.1 Configuration and Operation of Optical Phase Control Device and Display Device According to First Embodiment]
(Outline of phase modulator including optical phase controller)
FIG. 1 schematically illustrates a configuration example of a phase modulation device including an optical phase control device according to the first embodiment of the present disclosure.

The phase modulation device includes an optical phase modulation element 1 that modulates the phase of light from the light source 50, a phase distribution calculation circuit 51, and a phase modulation element drive circuit 52.

The optical phase control device according to the present disclosure includes at least a phase distribution calculation circuit 51 and a phase modulation element driving circuit 52.

The phase distribution calculation circuit 51 is a phase distribution calculation unit that generates target phase distribution data (phase modulation signal) based on an input signal. The target phase distribution data is data having a phase distribution that enables the target reproduction image 60 (target reproduction image) to be reproduced by the optical phase modulation element 1.

Here, for example, when the optical phase modulation element 1 is used as a part of the illumination device in the projector, the input signal is, for example, an image signal. In this case, the reproduced image 60 is an illumination image that illuminates the illumination target 5. The illumination object 5 is a light intensity modulation element such as an intensity modulation liquid crystal panel in a projector. In this case, the target phase distribution data is data having a phase distribution pattern capable of forming an illumination image having a luminance distribution corresponding to an image displayed by the projector.

The phase modulation element driving circuit 52 generates an applied voltage (drive voltage) based on the target phase distribution data generated by the phase distribution calculation circuit 51, and the optical phase modulation element so that each pixel 10 has a target phase distribution. 1 is driven.

The optical phase modulation element 1 modulates the phase of light from the light source 50 based on the applied voltage given by the phase modulation element drive circuit 52. The optical phase modulation element 1 may be a transmission type phase modulation element or a reflection type phase modulation element.

In the phase modulation apparatus of FIG. 1, when performing phase modulation of a plurality of lights having different wavelengths by the field sequential method, a plurality of lights having different wavelengths are emitted from the light source 50 in a time-sharing manner. The optical phase modulation element 1 modulates the phases of a plurality of lights from the light source 50 for each wavelength in a time division manner, and reproduces a plurality of reproduced images 60 for each wavelength in a time division manner. The phase distribution calculation circuit 51 generates a plurality of phase distribution data (target phase distribution data) for each wavelength corresponding to the plurality of reproduced images 60 for each wavelength reproduced by the optical phase modulation element 1. The phase modulation element driving circuit 52 generates a plurality of applied voltages for each wavelength to be applied to the optical phase modulation element 1 based on data of a plurality of phase distributions for each wavelength, and a plurality of voltages are applied to the optical phase modulation element 1. The light phase is modulated in a time-sharing manner for each wavelength.

(Outline of optical phase modulation element 1)
FIG. 2 shows an outline of the optical phase modulation element 1. FIG. 2 shows an example in which the optical phase modulation element 1 is composed of a phase modulation liquid crystal panel. The optical phase modulation element 1 includes, for example, a first glass substrate and a second glass substrate that are arranged to face each other. Between the first glass substrate and the second glass substrate, a liquid crystal layer containing liquid crystal molecules 14 is sealed by a sealing member (not shown).

A counter electrode (common electrode) 4 is provided on the first glass substrate. A plurality of pixel electrodes 11 (pixels 10) are provided on the second glass substrate.

When the optical phase modulation element 1 is a transmissive phase modulation element, both the counter electrode 4 and the pixel electrode 11 are configured by transparent electrodes that transmit light. When the optical phase modulation element is a reflection type phase modulation element, the counter electrode 4 is configured by a transparent electrode that transmits light, and the pixel electrode 11 is configured by a reflective electrode that reflects light.

A common voltage is applied to the counter electrode 4. An applied voltage corresponding to the input signal is applied to the plurality of pixel electrodes 11. The inclination of the liquid crystal molecules 14 in the optical phase modulation element 1 changes according to the applied voltage. As the inclination of the liquid crystal molecules 14 changes, the phase distribution (refractive index distribution) for the light passing through the element changes as shown in the lower part of FIG. Thereby, the optical action can be changed in units of pixels.

Such an optical phase modulation element 1 is used as a part of an illumination device that generates illumination light for the light intensity modulation element in a projector, for example.

(Example of application to display devices)
3 and 4 show first and second configuration examples of the projector as the display device according to the first embodiment using the phase modulation device of FIG. 3 and 4 show a configuration example of a projector that performs full-color display by a field sequential method.

The projector 100 shown in FIG. 3 and the projector 100A shown in FIG. 4 each include a light source 50, an optical phase modulation element 1, a light intensity modulation element 61, and a projection lens (projection optical system) 81. .

3 and 4 show a configuration example in which a transmission type phase modulation element is used as the optical phase modulation element 1, it may be constituted by a reflection type phase modulation element.

The projector 100 shown in FIG. 3 shows an example in which the light intensity modulation element 61 is constituted by a transmission type light intensity modulation element, for example, a transmission type intensity modulation liquid crystal display panel. The projector 100A shown in FIG. 4 shows an example in which the light intensity modulation element 61 is constituted by a reflection type light intensity modulation element, for example, a reflection type intensity modulation liquid crystal display panel.

The light source 50 has a red light source that emits red (R) light, a green light source that emits green (G) light, and a blue light source that emits blue (B) light. Each of the red light source, the green light source, and the blue light source is composed of, for example, one or a plurality of laser light sources. The light source 50 emits red light, green light, and blue light in a time-sharing manner.

In the

projectors

100 and 100 </ b> A, the optical phase modulation element 1 is illuminated with light of each color from the light source 50. At this time, the optical phase modulation element 1 is illuminated in a time division manner for each color of red light, green light, and blue light. The optical phase modulation element 1 displays the phase distribution pattern optimized for each wavelength of each color in a time division manner. The phase distribution calculation circuit 51 in FIG. 1 generates phase distribution data (target phase distribution data) of each color corresponding to the reproduction image 60 of each color reproduced by the optical phase modulation element 1. The phase modulation element driving circuit 52 generates an applied voltage of each color to be applied to the optical phase modulation element 1 based on the phase distribution data of each color, and changes the phase of the light of each color to the optical phase modulation element 1. Modulate in time division every time.

The light intensity modulation element 61 is irradiated with a reproduction image of each color formed by the optical phase modulation element 1 as illumination light in a time division manner for each color. The light intensity modulation element 61 performs intensity modulation on the illumination light of each color in synchronization with the timing at which the light source 50 emits each color light, and generates a projection image of each color in a time division manner.

Projected images of each color by red light, green light, and blue light are emitted toward the projection lens 81. The projection lens 81 projects the projection images of the respective colors on a projection surface such as the screen 80 in a time division manner.

In the above, the configuration example of the display device in which the optical phase modulation element 1 and the light intensity modulation element 61 are combined has been described. However, a display device that does not use the light intensity modulation element 61 may be used. For example, a display device may be used in which the reproduced image 60 itself is used as a display image instead of using the reproduced image 60 by the optical phase modulation element 1 as illumination light.

(Optimization of applied voltage for each wavelength)
FIG. 5 shows an example of the voltage range of each color necessary for the phase modulation of 0 to 2π in the display device according to the comparative example. In FIG. 5, the horizontal axis represents the applied voltage (V), and the vertical axis represents the phase (π). FIG. 6 shows an example of the relationship between the phase modulation amount and the applied voltage in the display device according to the comparative example. In FIG. 5, the horizontal axis represents the phase modulation amount (π), and the vertical axis represents the applied voltage (V).

As shown in FIG. 5, in the optical phase modulation element 1, R (red) voltage range Vr, G (green) voltage range Vg, and B (blue) modulation voltage required for phase modulation of 0 to 2π. The ranges Vb are different. As shown in FIGS. 5 and 6, the longer the wavelength, the larger the voltage range of the applied voltage. In the comparative example shown in FIGS. 5 and 6, the applied voltages are generated so that the maximum values of the voltage ranges are the same for each color of R, G, and B.

As described above, when the optical phase modulation element 1 is composed of a phase modulation liquid crystal panel, it is necessary to display the phase distribution pattern even when the optical phase modulation element 1 displays the same phase distribution pattern. The applied voltage differs for each wavelength. Therefore, when phase modulation of each color is performed in a time division manner, even if the phase distribution calculation circuit 51 can generate the phase distribution at high speed and high quality, a reproduced image caused by the response speed of the liquid crystal in the optical phase modulation element 1 60 degradation occurs.

FIG. 7 shows an example in which the same reproduced image 60 (checker pattern) is displayed by the optical phase modulation element 1 using different phase distributions in the display device according to the comparative example. FIG. 7 shows an ideal reproduced image (still image), a reproduced image immediately after switching of the phase distribution, and a reproduced image when the liquid crystal response in the optical phase modulation element 1 is completed, in order from the left side. Immediately after the phase distribution is switched, the liquid crystal response is not completed, and the reproduced image is deteriorated. This deterioration of the reproduced image appears as a decrease in brightness, a decrease in contrast, and generation of noise. When the liquid crystal response is completed, the luminance changes with time, flickering occurs, and the reproduced image deteriorates.

For this reason, when performing phase modulation and image display by the field sequential method, it is desirable to optimize the applied voltage for each wavelength as shown in FIGS.

FIG. 8 shows an example of the voltage range of each color necessary for the phase modulation of 0 to 2π in the display device (example) according to the first embodiment. In FIG. 8, the horizontal axis represents the applied voltage (V), and the vertical axis represents the phase (π). FIG. 9 shows an example of the relationship between the phase modulation amount and the applied voltage in the display device (example) according to the first embodiment. In FIG. 9, the horizontal axis represents the phase modulation amount (π), and the vertical axis represents the applied voltage (V).

In the optical phase control device and the display device according to the first embodiment, the phase modulation element driving circuit 52 has a different voltage range for each wavelength, and the longer the wavelength, the smaller the minimum value of the voltage range, and the maximum value becomes larger. A plurality of applied voltages for each wavelength are generated so as to increase. Specifically, the phase modulation element driving circuit 52 generates an applied voltage for each wavelength so as to satisfy the following conditions.
Rmin <Gmin <Bmin <Bmax <Gmax <Rmax
Here, the minimum value of the applied voltage of R is Rmin, and the maximum value is Rmax. The minimum value of the applied voltage of G is Gmin, and the maximum value is Gmax. The minimum value of the applied voltage of B is Bmin, and the maximum value is Bmax.

By optimizing the applied voltage as described above, it is possible to reduce the amount of voltage fluctuation at the time of wavelength switching.

FIGS. 10 to 12 are caused by switching of wavelengths when the same phase is displayed on the optical phase modulation element 1 in the display device according to the comparative example and the display device according to the first embodiment (example). An example of the relationship between the voltage fluctuation amount and its frequency is shown. 10 to 12, the horizontal axis indicates the voltage fluctuation amount, and the vertical axis indicates the frequency. The frequency corresponds to the number of pixels in which the voltage fluctuation amount appears.

FIG. 10 shows the amount of voltage fluctuation (difference in applied voltage) when the wavelength is switched between R and G. FIG. 11 shows the amount of voltage fluctuation (difference in applied voltage) when the wavelength is switched between G and B. FIG. 12 shows the amount of voltage fluctuation (difference in applied voltage) when the wavelength is switched between B and R.

As shown in FIG. 10 to FIG. 12, the display device (example) according to the first embodiment can be improved to a state where the frequency of occurrence of the voltage fluctuation amount is low compared to the display device according to the comparative example. I understand that.

As a method for setting the voltage range, the average value of the voltage range of the applied voltage in each color may be matched. For example, it is assumed that the phase modulation element driving circuit 52 generates an applied voltage quantized for each wavelength. In this case, for example, if the number of applied voltage divisions (number of quantization levels) for each color is _N and the applied voltage corresponding to the division point is V _N , (ΣV _N ) / N may be set to match. Good.

[1.2 Effects]
As described above, according to the optical phase control device and the display device according to the first embodiment, the voltage range differs for each wavelength, and the longer the wavelength, the smaller the minimum value of the voltage range, and the maximum value. Is increased so that a plurality of applied voltages for each wavelength applied to the optical phase modulation element 1 are generated, so that the image quality of the reproduced image 60 by the optical phase modulation element 1 can be improved.

According to the optical phase control device and the display device according to the first embodiment, for example, noise reduction, luminance improvement, contrast improvement, flicker suppression, and color reproducibility improvement of the reproduced image 60 by the optical phase modulation element 1, In addition, effects such as suppression of afterimages between frames can be obtained.

It should be noted that the effects described in this specification are merely examples and are not limited, and other effects may be obtained. The same applies to the effects of the other embodiments thereafter.

<2. Second Embodiment>
Next, an optical phase control device and a display device according to the second embodiment of the present disclosure will be described. In the following description, substantially the same components as those of the optical phase control device and the display device according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate.

FIG. 13 shows an example of the voltage range of each color necessary for phase modulation of 0 to about 2π in the display device according to the comparative example. In FIG. 13, the horizontal axis represents the applied voltage (V), and the vertical axis represents the phase (π). FIG. 13 shows an example of the relationship between the phase modulation amount and the applied voltage in the display device according to the comparative example. In FIG. 13, the horizontal axis represents the phase modulation amount (π), and the vertical axis represents the applied voltage (V).

FIG. 15 shows an example of the voltage range of each color necessary for phase modulation of 0 to about 2π in the display device (example) according to the second embodiment. In FIG. 15, the horizontal axis represents the applied voltage (V), and the vertical axis represents the phase (π). FIG. 16 shows an example of the relationship between the phase modulation amount and the applied voltage in the display device (example) according to the second embodiment. In FIG. 16, the horizontal axis represents the phase modulation amount (π), and the vertical axis represents the applied voltage (V).

The setting of the voltage range in the comparative example of FIG. 13 is substantially the same as that of the comparative example (FIG. 5) for the first embodiment except for the longest wavelength applied voltage (R applied voltage). Further, the voltage range in the display device (example) according to the second embodiment shown in FIG. 15 is the same as that of the first embodiment (FIG. 15) except for the applied voltage having the longest wavelength (applied voltage of R). This is substantially the same as 8).

In the display device according to the comparative example and the display device according to the second embodiment (example), the phase modulation element driving circuit 52 generates an applied voltage quantized for each wavelength. Further, the plurality of applied voltages for each wavelength are quantized so that the number of quantization levels of the applied voltage of the longest wavelength is smaller than the number of quantization levels of the applied voltages of other wavelengths.

When the same phase modulation amount is required for each wavelength, the voltage range of the applied voltage becomes wider as the wavelength becomes longer. Therefore, by lowering the quantization level of the phase distribution on the long wavelength side, the voltage range of the applied voltage can be reduced, and the voltage range of the applied voltage of each wavelength can be made closer. The voltage fluctuation amount can be made smaller.

In the display device according to the comparative example and the display device according to the second embodiment (example), the quantization level of the applied voltage of R is 16 levels, and the maximum modulation amount is 1.85π. The G and B quantization levels are, for example, 256 levels, and the maximum modulation amount is 2π.

17 and 18 show the switching of wavelengths when the same phase is displayed on the optical phase modulation element 1 in the display device according to the comparative example and the display device according to the second embodiment (example). An example of the relationship between the generated voltage fluctuation amount and its frequency is shown. 17 and 18, the horizontal axis indicates the voltage fluctuation amount, and the vertical axis indicates the frequency. The frequency corresponds to the number of pixels in which the voltage fluctuation amount appears.

FIG. 17 shows the amount of voltage fluctuation (difference in applied voltage) when the wavelength is switched between R and G. FIG. 18 shows the amount of voltage fluctuation (difference in applied voltage) when the wavelength is switched between B and R.

As shown in FIGS. 17 and 18, the display device (example) according to the second embodiment can be improved to a state where the frequency of occurrence of the voltage fluctuation amount is lower than the display device according to the comparative example. I understand that.

Other configurations, operations, and effects may be substantially the same as those of the optical phase control device and the display device according to the first embodiment.

<3. Third Embodiment>
Next, an optical phase control device and a display device according to a third embodiment of the present disclosure will be described. In the following description, substantially the same components as those of the optical phase control device and the display device according to the first or second embodiment will be denoted by the same reference numerals, and description thereof will be omitted as appropriate.

In the third embodiment, a specific example of phase distribution generation by the phase distribution calculation circuit 51 will be described.

(First example)
The phase distribution calculation circuit 51 in FIG. 1 sequentially generates a plurality of phase distribution data for each wavelength. At this time, the phase distribution calculation circuit 51 changes the voltage between the applied voltage generated based on the phase distribution data generated immediately before in time and the applied voltage generated based on the current phase distribution data. It is desirable to generate a plurality of phase distribution data so that the amount is minimized. For example, the phase distribution calculation circuit 51 preferably generates current phase distribution data with reference to the phase distribution data generated immediately before in time.

Since the image quality of the reproduced image 60 is improved as the phase distribution between the frames is closer, it is desirable to generate the phase distribution so that the voltage fluctuation between the frames becomes smaller when the phase distribution calculation circuit 51 generates the phase distribution. . For the generation of the phase distribution, there is a GS method for generating a phase distribution by repeating Fourier transform shown in FIG. 19 described below. By making the random initial phase given when generating this phase distribution the final phase distribution of the previous frame, the converging phase distribution can be made closer between frames. As a result, voltage fluctuation is reduced, and the quality of the reproduced image 60 is improved.

FIG. 19 shows a first example of a method for generating target phase distribution data in the display device according to the third embodiment. Here, a case where target phase distribution data is generated by the GS method will be described as an example, but the phase distribution calculation method may be other than the GS method. As a calculation method of the phase distribution, for example, there are a method of deriving the phase distribution from a diffraction approximate expression of the Fresnel region or the Fraunhofer region, and a method of deriving the phase distribution as a free-form surface lens instead of diffraction. The GS method is a method of deriving the phase distribution from the diffraction approximate expression of the Fraunhofer region, but the method of calculating the phase distribution in the present disclosure is not limited to this.

As shown in FIG. 19, the phase distribution calculation circuit 51 may generate target phase distribution data by a GS method as a predetermined phase distribution calculation method.

The phase distribution calculation circuit 51 gives a random initial phase as an initial condition to the target reproduction image having the intensity distribution to be reproduced, and performs inverse Fourier transform (step S101). The phase distribution calculation circuit 51 may replace the phase of the phase and amplitude obtained thereby with a uniform phase (step S102) to obtain the target phase distribution. Here, the reason why the phase is replaced with a uniform phase is that it is assumed that the optical phase modulation element 1 performs reproduction using parallel light.

Next, the phase distribution calculation circuit 51 performs reproduction calculation by performing Fourier transform on the phase and amplitude obtained in step S102 (step S103). Thereby, a reproduced image is calculated.

Next, the phase distribution calculation circuit 51 replaces the amplitude of the phase and amplitude obtained in step S103 with the amplitude of the target reproduction image (step S104).

Next, the phase distribution calculation circuit 51 performs inverse Fourier transform on the phase and amplitude obtained in step S104 (step S105), and thereafter repeats calculation (iteration) that repeats the calculations in steps S102 to S105. Do. The iterative calculation may be performed until a reproduced image having a quality satisfying as the target reproduced image is obtained.

When the same target reproduction image is to be reproduced over a plurality of frames or a plurality of subframes in the optical phase modulation element 1, the phase distribution calculation circuit 51 performs the above GS method for each frame or each subframe. Of the calculations, the phase distribution of the target phase distribution data may be changed by changing at least the random initial phase over time (step S201).

Further, in the same case, the phase distribution calculation circuit 51 changes the phase distribution of the target phase distribution data by changing at least the number of repetitive calculations in time among the calculations by the GS method. It is also possible (step S202).

(Second example)
FIG. 20 shows a second example of a method for generating target phase distribution data in the display device according to the third embodiment. In this second example, the phase distribution calculation circuit 51 generates target phase distribution data by a table method.

The phase modulation device may include a storage unit 71 that stores data of a plurality of partial phase distributions each capable of reproducing the same reproduced image. As illustrated in FIG. 20, the storage unit 71 may store a plurality of partial phase distribution data as a phase distribution data table.

The phase distribution calculation circuit 51 may generate target phase distribution data by combining partial phase distribution data stored in the storage unit 71. The phase distribution calculation circuit 51 may partially change the phase distribution of the target phase distribution data by randomly changing the combination of the partial phase distribution data in terms of time.

As shown in FIG. 20, the phase distribution calculation circuit 51 divides the target reproduction image into a plurality of divided regions, and generates the target phase distribution data by combining the partial phase distribution data for each divided region. May be. In this case, for example, assuming that the number of divided regions is N and the number of partial phase distribution data held as a phase distribution data table is M, ^MN phase distribution combinations are possible. Even if the number M of partial phase distribution data is small, it is possible to generate a substantially random phase distribution as a whole by increasing the number of divided regions (for example, thousands).

In the above second example, it is desirable that the partial phase distribution data stored in the storage unit 71 is a similar pattern or the same pattern for each wavelength. As a result, the phase distribution can be made close between frames, so that the voltage fluctuation is reduced and the quality of the reproduced image 60 is improved.

Other configurations, operations, and effects may be substantially the same as those of the optical phase control device and the display device according to the first or second embodiment.

<4. Other Embodiments>
The technology according to the present disclosure is not limited to the description of each of the above embodiments, and various modifications can be made.

For example, this technique can also take the following structures.
According to the present technology having the following configuration, the voltage range is different for each wavelength, and the longer the wavelength, the smaller the minimum value of the voltage range and the larger the maximum value. Thus, it is possible to improve the image quality of the reproduced image by the optical phase modulation element.
(1)
A phase distribution arithmetic circuit that generates data of a plurality of phase distributions for each wavelength corresponding to a reproduction image for each wavelength reproduced by the optical phase modulation element;
Based on the data of the plurality of phase distributions for each wavelength, a plurality of applied voltages for each wavelength to be applied to the optical phase modulation element are generated, and the wavelength of each wavelength incident on the optical phase modulation element in a time division manner is generated. And a drive circuit that modulates the phase of a plurality of different lights by wavelength for each wavelength,
The drive circuit is
An optical phase control device that generates the plurality of applied voltages in such a manner that the voltage range differs for each wavelength and the longer the wavelength, the smaller the minimum value of the voltage range and the larger the maximum value.
(2)
The plurality of lights includes red light, green light, and blue light,
The plurality of applied voltages include a red applied voltage, a green applied voltage, and a blue applied voltage,
The minimum value of the red applied voltage is Rmin, the maximum value is Rmax,
The minimum value of the green applied voltage is Gmin, the maximum value is Gmax,
The minimum value of the blue applied voltage is Bmin, the maximum value is Bmax,
When
The drive circuit generates the plurality of applied voltages so as to satisfy the following conditions: Rmin <Gmin <Bmin <Bmax <Gmax <Rmax
The optical phase control device according to (1) above.
(3)
The drive circuit is
The plurality of applied voltages are quantized so that the number of quantization levels of the applied voltage with the longest wavelength is smaller than the number of quantization levels of the applied voltages with other wavelengths. (1) or (2) Optical phase control device.
(4)
The phase distribution calculation circuit is configured to sequentially generate data of the plurality of phase distributions for each wavelength. The applied voltage generated based on the phase distribution data generated one time earlier and the current The data of the plurality of phase distributions is generated so that a voltage change amount with the applied voltage generated based on the data of the phase distribution is minimized. The one of the above (1) to (3) Optical phase control device.
(5)
The optical phase control device according to (4), wherein the phase distribution calculation circuit generates the current phase distribution data with reference to the phase distribution data generated one time before.
(6)
A light source that emits a plurality of lights having different wavelengths in a time-sharing manner;
An optical phase modulation element that modulates the phase of the plurality of lights from the light source for each wavelength in a time division manner and reproduces a plurality of reproduction images for each wavelength in a time division manner;
A phase distribution calculation circuit that generates data of a plurality of phase distributions for each wavelength corresponding to the plurality of reproduced images for each wavelength reproduced by the optical phase modulation element;
Based on the data of the plurality of phase distributions for each wavelength, a plurality of applied voltages for each wavelength to be applied to the optical phase modulation element are generated, and the phases of the plurality of lights are converted to wavelengths with respect to the optical phase modulation element. Each with a drive circuit that modulates in a time-sharing manner,
The drive circuit is
A display device that generates the plurality of applied voltages such that the voltage range differs for each wavelength and the minimum value of the voltage range decreases and the maximum value increases as the wavelength increases.
(7)
The display device according to (6), further including: a light intensity modulation element that generates the image by using the reproduced image by the optical phase modulation element as illumination light and modulating the intensity of the illumination light.

This application claims priority on the basis of Japanese Patent Application No. 2018-084690 filed on April 26, 2018 at the Japan Patent Office. The entire contents of this application are incorporated herein by reference. This is incorporated into the application.

Those skilled in the art will envision various modifications, combinations, subcombinations, and changes, depending on design requirements and other factors, which are within the scope of the appended claims and their equivalents. It is understood that

Claims

A phase distribution arithmetic circuit that generates data of a plurality of phase distributions for each wavelength corresponding to a reproduction image for each wavelength reproduced by the optical phase modulation element;
Based on the data of the plurality of phase distributions for each wavelength, a plurality of applied voltages for each wavelength to be applied to the optical phase modulation element are generated, and the wavelength of each wavelength incident on the optical phase modulation element in a time division manner is generated. And a drive circuit that modulates the phase of a plurality of different lights by wavelength for each wavelength,
The drive circuit is
An optical phase control device that generates the plurality of applied voltages in such a manner that the voltage range differs for each wavelength and the longer the wavelength, the smaller the minimum value of the voltage range and the larger the maximum value.
The plurality of lights includes red light, green light, and blue light,
The plurality of applied voltages include a red applied voltage, a green applied voltage, and a blue applied voltage,
The minimum value of the red applied voltage is Rmin, the maximum value is Rmax,
The minimum value of the green applied voltage is Gmin, the maximum value is Gmax,
The minimum value of the blue applied voltage is Bmin, the maximum value is Bmax,
When
The drive circuit generates the plurality of applied voltages so as to satisfy the following conditions: Rmin <Gmin <Bmin <Bmax <Gmax <Rmax
The optical phase control device according to claim 1.
The drive circuit is
The optical phase control device according to claim 1, wherein the plurality of applied voltages are quantized so that the number of quantization levels of the applied voltage having the longest wavelength is smaller than the number of quantization levels of the applied voltages of other wavelengths. .
The phase distribution calculation circuit is configured to sequentially generate data of the plurality of phase distributions for each wavelength. The applied voltage generated based on the phase distribution data generated one time earlier and the current The optical phase control device according to claim 1, wherein the plurality of phase distribution data are generated so that a voltage change amount with respect to an applied voltage generated based on the phase distribution data is minimized.
The optical phase control device according to claim 4, wherein the phase distribution calculation circuit generates the current phase distribution data with reference to the phase distribution data generated immediately before in time.
A light source that emits a plurality of lights having different wavelengths in a time-sharing manner;
An optical phase modulation element that modulates the phase of the plurality of lights from the light source for each wavelength in a time division manner and reproduces a plurality of reproduction images for each wavelength in a time division manner;
A phase distribution calculation circuit that generates data of a plurality of phase distributions for each wavelength corresponding to the plurality of reproduced images for each wavelength reproduced by the optical phase modulation element;
Based on the data of the plurality of phase distributions for each wavelength, a plurality of applied voltages for each wavelength to be applied to the optical phase modulation element are generated, and the phases of the plurality of lights are converted to wavelengths with respect to the optical phase modulation element. Each with a drive circuit that modulates in a time-sharing manner,
The drive circuit is
A display device that generates the plurality of applied voltages such that the voltage range differs for each wavelength and the minimum value of the voltage range decreases and the maximum value increases as the wavelength increases.
The display device according to claim 6, further comprising: a light intensity modulation element that uses the reproduced image by the optical phase modulation element as illumination light and modulates the intensity of the illumination light to generate an image.