Holographic display system, holographic display method and electronic device

Abstract

The present application provides a holographic display system and a holographic display method and an electronic device thereof. The holographic display system comprises: a backlight module, a spatial light modulator and a plurality of liquid crystal grating modules arranged in sequence in a first direction; the backlight module is used to emit a backlight beam; the spatial light modulator is used to perform phase modulation and amplitude modulation on the backlight beam; a plurality of liquid crystal grating modules are arranged in sequence in the first direction; based on the polarization direction of the incident light, the liquid crystal grating module can change the propagation direction of the incident light or maintain the propagation direction of the incident light; wherein, the light incident side of at least one liquid crystal grating module has a first optical rotation device, and the first optical rotation device can rotate the polarization direction of the incident light, so that in a set time period, at least one liquid crystal grating module changes the propagation direction of the incident light, and at least one liquid crystal grating module does not change the propagation direction of the incident light. The technical solution of the present application can reduce the screen refresh frequency of the liquid crystal grating module.

Description

Technical Field

[0001] The present application relates to the field of holographic display technology, and more specifically, to a holographic display system and a holographic display method and an electronic device. Background Art

[0002] In order to meet people's demand for stereoscopic display of electronic devices, electronic devices with 3D holographic display function have become a major development direction in the current display field. Electronic devices can realize 3D holographic display function by integrating holographic display system.

[0003] The holographic display system needs to be equipped with a liquid crystal grating module to adjust the propagation direction of light to form left and right eye images, thereby realizing 3D holographic display. In the existing holographic display system, the liquid crystal grating module is required to have a high picture refresh rate. Summary of the invention

[0004] In view of this, the present application provides a holographic display system and a holographic display method and an electronic device, which can reduce the image refresh frequency of the liquid crystal grating module. The scheme is as follows:

[0005] In a first aspect, the present application provides a holographic display system, comprising:

[0006] A backlight module, a spatial light modulator and a plurality of liquid crystal grating modules are sequentially arranged in a first direction;

[0007] The backlight module is used to emit a backlight beam;

[0008] The spatial light modulator is used to perform phase modulation and amplitude modulation on the backlight beam;

[0009] A plurality of liquid crystal grating modules are arranged in sequence in a first direction; based on the polarization direction of the incident light, the liquid crystal grating module can change the propagation direction of the incident light or maintain the propagation direction of the incident light;

[0010] Among them, at least one liquid crystal grating module has a first optical rotation device on the light incident side, and the first optical rotation device can rotate the polarization direction of the incident light, so that in a set time period, at least one liquid crystal grating module changes the propagation direction of the incident light, and at least one liquid crystal grating module does not change the propagation direction of the incident light.

[0011] The holographic display system provided by the present invention has a plurality of liquid crystal grating modules, and the first optical rotation device can make at least one liquid crystal grating module change the propagation direction of the incident light within a set time period, and at least one liquid crystal grating does not change the propagation direction of the incident light. In this way, at the same time, some liquid crystal grating modules deflect the propagation direction of the incident light, and some liquid crystal gratings do not need to deflect the propagation direction of the incident light, thereby reducing the picture refresh frequency of the liquid crystal grating module.

[0012] In a second aspect, the present application provides a holographic display method based on the above holographic display system, comprising:

[0013] Emits a backlight beam through a backlight module;

[0014] Phase modulation and amplitude modulation of the backlight beam are performed by a spatial light modulator;

[0015] Based on the first optical rotation device, within a set time period, at least one liquid crystal grating module changes the propagation direction of the incident light, and at least one liquid crystal grating module does not change the propagation direction of the incident light.

[0016] The holographic display method provided in the present application adopts the above-mentioned holographic display system. When performing holographic display, at the same time, part of the liquid crystal grating modules deflect the propagation direction of the incident light, and part of the liquid crystal grating does not need to deflect the propagation direction of the incident light, thereby reducing the image refresh frequency of the liquid crystal grating module.

[0017] In a third aspect, the present application provides an electronic device comprising the above-mentioned holographic display system.

[0018] The electronic device provided by the present application includes the above-mentioned holographic display system. When performing holographic display, at the same time, part of the liquid crystal grating module deflects the propagation direction of the incident light, and part of the liquid crystal grating does not need to deflect the propagation direction of the incident light, thereby reducing the image refresh frequency of the liquid crystal grating module. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0020] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which this application can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by this application, should still fall within the scope of the technical contents disclosed in this application.

[0021] Figure 1 is a structural schematic diagram of a holographic display system;

[0022] Figure 2A schematic diagram of the structure of a holographic display system provided in an embodiment of the present application;

[0023] Figure 3 A cross-sectional view of a liquid crystal optical rotation device provided in an embodiment of the present application;

[0024] Figure 4 A schematic diagram of the principle of rotating the polarization direction of light by a first optical rotator having a liquid crystal optical rotator;

[0025] Figure 5 A cross-sectional view of a first optical rotation device provided in an embodiment of the present application;

[0026] Figure 6 for Figure 5 A schematic structural diagram of a liquid crystal optical rotator device in the first optical rotator device;

[0027] Figure 7 for Figure 5 A schematic structural diagram of another liquid crystal optical rotator device in the first optical rotator device;

[0028] Figure 8-Figure 13 A schematic diagram of the working principle of a liquid crystal optical rotation device provided in an embodiment of the present application;

[0029] Fig.14 A schematic diagram of the structure of a liquid crystal grating module provided in an embodiment of the present application;

[0030] Fig.15 A schematic diagram of the structure of a liquid crystal grating provided in an embodiment of the present application;

[0031] Fig.16 A schematic diagram of the layout of a first optical rotation device and a liquid crystal grating module provided in an embodiment of the present application;

[0032] Fig.17 A schematic diagram of the structure of a liquid crystal grating module provided in an embodiment of the present application;

[0033] Fig.18 A top view of a liquid crystal grating module with each liquid crystal grating aligned in a first direction;

[0034] Fig.19 A top view of another liquid crystal grating module with each liquid crystal grating aligned in a first direction;

[0035] Fig. 20 A schematic diagram of the layout of a liquid crystal grating module in a holographic display system provided in an embodiment of the present application;

[0036] Fig.21 and Fig. 22A schematic diagram of the principle of adjusting light in two adjacent frames of monochrome sub-images in a holographic display system provided in an embodiment of the present application;

[0037] Fig.23 A schematic diagram of another layout of a first optical rotation device and a liquid crystal grating module provided in an embodiment of the present application;

[0038] Fig.24 A top view of two adjacent liquid crystal grating modules with the alignment direction of each liquid crystal grating facing the first direction;

[0039] Fig.25 and Fig.26 A schematic diagram of the principle of adjusting light in two adjacent frames of monochrome sub-images in another holographic display system provided in an embodiment of the present application;

[0040] Fig. 27 for Figure 1 A timing diagram of the holographic display system shown;

[0041] Fig.28 A timing diagram of a holographic display system provided in an embodiment of the present application;

[0042] Fig.29 A schematic diagram of the structure of another holographic display system provided in an embodiment of the present application;

[0043] Fig.30 A schematic diagram of a flow chart of a holographic display method provided in an embodiment of the present application;

[0044] Fig.31 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the embodiments in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0046] refer to Figure 1 As shown, Figure 1 is a structural diagram of a holographic display system. Figure 1 The holographic display system shown includes a backlight module 11, a spatial light modulator 12 and a liquid crystal grating module 13 which are arranged in sequence.

[0047] The backlight module 11 is used to emit a backlight beam, and the emitted backlight beam includes at least a red backlight sub-beam, a green backlight sub-beam, and a blue backlight sub-beam emitted in a time-sharing manner. The spatial light modulator 12 is used to perform phase modulation and amplitude modulation on the backlight beam. The liquid crystal grating module 13 forms a left eye image and a right eye image based on the incident light.

[0048] for Figure 1 The holographic display system shown in the figure deflects the propagation direction of light only through one liquid crystal grating module 13, and the liquid crystal grating module 13 needs to have a higher picture refresh frequency. Specifically, if both the left eye and the right eye are to perceive the picture refresh frequency of the first set frequency, the liquid crystal grating module 13 needs to have a picture refresh frequency of the second set frequency, wherein the second set frequency is 6 times the first set frequency. This is because the liquid crystal grating module 13 needs to form left and right eye images respectively, and each frame of the left eye image and each frame of the right eye image include a red photon image, a green photon image, and a blue photon image. The refresh frequency of each color sub-image is the first set frequency, so the refresh frequency of the left eye image and the right eye image is 3 times the first set frequency. The liquid crystal grating module 13 needs to display the left eye image and the right eye image in time-sharing, so the picture refresh frequency of the liquid crystal grating module 13 needs to be 6 times the first set frequency.

[0049] If you want both the left and right eyes to perceive 60Hz images, Figure 1 In the illustrated embodiment, the image refresh frequency of the liquid crystal grating module 13 is required to be 360 ​​Hz. The holographic display system has a relatively high requirement on the image refresh frequency of the liquid crystal grating module 13 .

[0050] In conventional technology, the image refresh frequency of the liquid crystal grating module 13 is generally reduced by sacrificing the human eye perception frequency, that is, by reducing the first set frequency, the purpose of reducing the second set frequency is achieved, thereby reducing the image refresh frequency of the liquid crystal grating module 13. However, if the first set frequency is too low, it will cause flickering and jittering of the displayed image, affecting the display quality. The inventor has found that the first set frequency can be reduced to 40Hz at most. Further reducing the first set frequency will cause serious flickering and jittering problems.

[0051] It can be seen from the above description that the first set frequency and the second set frequency are a contradiction. If the first set frequency is increased, the image display quality will be improved, but it will lead to a significant increase in the second set frequency, thereby greatly increasing the requirements for the screen refresh frequency of the liquid crystal grating module 13. If the first set frequency is reduced, the requirements for the screen refresh frequency of the liquid crystal grating module 13 can be reduced, but it will affect the image display quality. Therefore, only a compromise can be made between the two, and the first set frequency is generally set to 60Hz.

[0052] In view of this, the technical solution of the present application provides a holographic display system, a holographic display method and an electronic device, in which a plurality of liquid crystal grating modules are arranged in the holographic display system, and a first optical rotation device is used to make at least one liquid crystal grating module change the propagation direction of the incident light within a set time period, and at least one liquid crystal grating does not change the propagation direction of the incident light. In this way, at the same time, some liquid crystal grating modules deflect the propagation direction of the incident light, and some liquid crystal gratings do not need to deflect the propagation direction of the incident light, thereby reducing the picture refresh frequency of the liquid crystal grating module.

[0053] Furthermore, it is assumed that the holographic display system has N liquid crystal grating modules, where N is a positive integer greater than 1. In a display period of a frame of a monochrome sub-image, only one liquid crystal grating module deflects the propagation direction of the incident light, and other liquid crystal grating modules do not need to deflect the propagation direction of the incident light, and the second frequency is jointly realized by the N liquid crystal grating modules, and the image refresh frequency of a single liquid crystal grating module is reduced to 1 / N of the second frequency.

[0054] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0055] refer to Figure 2 As shown, Figure 2 A structural schematic diagram of a holographic display system provided in an embodiment of the present application, wherein the holographic display system includes: a backlight module 21, a spatial light modulator 22, and a plurality of liquid crystal grating modules 23 arranged in sequence in a first direction Z.

[0056] The backlight module 21 is used to emit a backlight beam. The first direction Z is parallel to the propagation direction of the backlight emitted by the backlight module 21. The spatial light modulator 22 is used to perform phase modulation and amplitude modulation on the backlight beam. A plurality of liquid crystal grating modules 23 are arranged in sequence in the first direction Z. Based on the polarization direction of the incident light, the liquid crystal grating module 23 can change the propagation direction of the incident light or maintain the propagation direction of the incident light, that is, for any liquid crystal grating module 23, the propagation direction of the light incident on the liquid crystal grating module 23 can be deflected, or the propagation direction of the light incident on the liquid crystal grating module 23 can be maintained.

[0057] The light incident side of at least one liquid crystal grating module 23 is provided with a first optical rotation device 24, and the first optical rotation device 24 can rotate the polarization direction of the incident light, so that in a set time period, at least one liquid crystal grating module 23 changes the propagation direction of the incident light, and at least one liquid crystal grating module 23 does not change the propagation direction of the incident light. The set time period can be the display time of a frame of monochrome sub-image displayed by the holographic display system.

[0058] The holographic display system provided in the embodiment of the present application has a first optical rotation device 24 capable of adjusting the polarization direction of light. The first optical rotation device 24 can adjust the polarization direction of light incident on each liquid crystal grating module 23, so that within a set time period, at least one liquid crystal grating module 23 changes the propagation direction of the incident light, and at least one liquid crystal grating module 23 does not change the propagation direction of the incident light. In this way, at the same time, some liquid crystal grating modules deflect the propagation direction of the incident light, and some liquid crystal gratings do not need to deflect the propagation direction of the incident light, thereby reducing the screen refresh frequency of the liquid crystal grating module.

[0059] for Figure 1 The holographic display system shown as having a single liquid crystal grating module 13, if the single liquid crystal grating module 13 needs to refresh 360 frames of monochrome sub-images within 1 second (that is, the picture refresh frequency is 360Hz), the holographic display system provided by the technical solution of the present application can be used to refresh 360 frames of monochrome sub-images within 1 second through multiple liquid crystal grating modules 23. If there are two liquid crystal grating modules 23, during the display time of a frame of monochrome sub-image, one liquid crystal grating module 23 changes the propagation direction of the incident light, and the other liquid crystal grating module 23 does not change the propagation direction of the incident light, and the two liquid crystal grating modules 23 alternately deflect the propagation direction of the light, then each liquid crystal grating module 23 can refresh 180 frames of monochrome sub-images within 1 second, and the picture refresh frequency of each liquid crystal grating module 23 is 180Hz, relative to Figure 1 The method shown in the figure reduces the image refresh frequency of the liquid crystal grating module 23 by half. If there are three liquid crystal grating modules 23, within the display time of one frame of monochrome sub-image, one liquid crystal grating module 23 changes the propagation direction of the incident light, and the other two liquid crystal grating modules 23 do not change the propagation direction of the incident light, and the three liquid crystal grating modules 23 alternately deflect the propagation direction of the light, then each liquid crystal grating module 23 can refresh 120 frames of monochrome sub-images within 1 second, and the image refresh frequency of each liquid crystal grating module 23 is 120Hz, which is relatively Figure 1 The manner shown reduces the image refresh frequency of the liquid crystal grating module 23 by two thirds.

[0060] It can be seen that the holographic display system provided in the application can greatly reduce the image refresh frequency of the liquid crystal grating module 23, thereby reducing the requirements for the image refresh frequency of the liquid crystal grating module 23.

[0061] In the embodiment of the present application, the first optical rotator 24 has a first working mode and a second working mode. In the first working mode, the incident light can maintain its polarization direction while passing through the first optical rotator 24. In the second working mode, after the incident light passes through the first optical rotator 24, its polarization direction rotates by a set angle.

[0062] It can be set that in the first working mode, the first optical rotator 24 can make the incident light transmit while maintaining the polarization direction; in the second working mode, the first optical rotator 24 can rotate the polarization direction of the incident light by (n-1)*180°+90° before transmitting, that is, the above-mentioned setting angle is (n-1)*180°+90°. n is a positive integer, and the direction of the rotation axis is perpendicular to the plane where the first optical rotator 24 is located. The direction of the rotation axis is parallel to the first direction Z.

[0063] The first optical rotator 24 is provided with a first working mode and a second working mode. By switching the working mode of the first optical rotator 24, it is possible to select whether to change the polarization direction of the light passing through the first optical rotator 24, thereby controlling whether each transmissive liquid crystal grating module 23 deflects the propagation direction of the incident light, so that within a set time period, at least one liquid crystal grating module 23 changes the propagation direction of the incident light, and at least one liquid crystal grating module 23 does not change the propagation direction of the incident light, so as to reduce the picture refresh frequency of the liquid crystal grating module 23.

[0064] refer to Figure 3 As shown, Figure 3 A cross-sectional view of a liquid crystal optical rotation device provided in an embodiment of the present application, combined with Figure 2 and Figure 3 As shown, the cut plane is parallel to the first direction Z. The first optical rotator 24 includes: at least one liquid crystal optical rotator 240; the liquid crystal optical rotator 240 includes: a first electrode layer 241 and a second electrode layer 242 arranged opposite to each other; and a first liquid crystal layer 243 located between the first electrode layer 241 and the second electrode layer 242. The liquid crystal optical rotator 240 is an electrically controlled birefringent liquid crystal cell (ECB).

[0065] The first electrode layer 241 and the second electrode layer 242 are both transparent electrode layers. A first alignment layer is disposed between the first electrode layer 241 and the second electrode layer 242 and the first liquid crystal layer 243, respectively, so that the liquid crystal molecules of the first liquid crystal layer 243 have a desired initial alignment direction.

[0066] By applying a set control voltage to the first electrode layer 241 and the second electrode layer 242, the state of the liquid crystal molecules in the first liquid crystal layer 243 can be adjusted, thereby selecting whether to rotate the polarization direction of the transmitted light. The holographic display system can be provided with a controller, and the controller is connected to the electrode layer of the liquid crystal optical rotation device 240. The controller provides different control voltages to the liquid crystal optical rotation device 240 to control the rotation of the liquid crystal molecules, thereby automatically controlling the first working mode or the second working mode.

[0067] In the first working mode, the controller is used to provide a first control voltage to the first electrode layer 241 and the second electrode layer 242 so that the long axis of the liquid crystal molecules is as follows: Figure 3The plane where the first optical rotator 24 is located is perpendicular to the first direction Z. At this time, the long axis of the liquid crystal molecules in the liquid crystal optical rotator 240 is parallel to the first direction Z, and the light can pass through the liquid crystal optical rotator 240 without changing the polarization direction.

[0068] In this application, vertical includes: completely vertical at an angle of 90° or approximately vertical at an angle approximately equal to 90°; parallel includes: completely parallel at an angle of 0° or approximately parallel at an angle approximately equal to 0°.

[0069] In the second working mode, the controller is used to provide a second control voltage to the first electrode 241 and the second electrode layer 242, so that the long axis of the liquid crystal molecules and the plane where the first optical rotator 24 is located have an angle of not less than 0° and less than 90°; wherein the first control voltage is different from the second control voltage. At this time, the liquid crystal optical rotator 240 can rotate the polarization direction of the incident light, so that the polarization direction of the light passing through the liquid crystal optical rotator 240 is reversely rotated.

[0070] In the embodiment of the present application, the controller provides corresponding control voltages to the first electrode 241 and the second electrode layer 242 to automatically control whether the liquid crystal optical rotator 240 changes the polarization direction of the transmitted light, thereby automatically selecting the working mode of the first optical rotator 24 .

[0071] The backlight module 21 can at least emit red backlight sub-beams, green backlight sub-beams, and blue backlight sub-beams in time-sharing, so that the holographic display system can perform color 3D holographic display based on the red, green, and blue three-primary color backlights. Obviously, the backlight module can also emit other color sub-beams that are time-sharing with the three primary color backlight sub-beams. Other color backlight sub-beams include: white backlight sub-beams for adjusting display brightness, and / or, preset color backlight sub-beams for adjusting display tone, the color of the preset color backlight is different from the red backlight, the blue backlight, and the green backlight.

[0072] The first optical rotator 24 needs to perform optical rotation on the backlight sub-beams of different colors. Since the wavelengths of red light, green light and blue light are different, when the first optical rotator 24 includes a liquid crystal optical rotator 240, if the liquid crystal optical rotator 240 uses the same first control voltage and second control voltage to perform mode control on the backlight sub-beams of different colors, it will cause deviation in the rotation angle of the polarization direction of the light in the second working mode.

[0073] refer to Figure 4 As shown, Figure 4FIG. 1 is a schematic diagram showing the principle of rotating the polarization direction of light by a first optical rotator having a liquid crystal optical rotator. The plane where the first optical rotator 24 having a liquid crystal optical rotator 240 is located is assumed to be parallel to the XY plane of a rectangular coordinate system. The alignment direction ( Figure 4 The dotted line in the middle (shown as the middle dotted line) has an included angle of 45° with the X-axis and the Y-axis of the rectangular coordinate system respectively. In the second working mode, the polarization direction of the incident light can be rotated 90°.

[0074] exist Figure 4 In the illustrated manner, taking the red backlight sub-beam as an example, its polarization direction before optical rotation is set to be parallel to the X-axis, and the polarization direction of the red backlight sub-beam before optical rotation can be decomposed into a first component and a second component that are perpendicular to each other.

[0075] When no power is applied, it is in the second working mode, and the long axis of the liquid crystal molecules is parallel to the alignment direction of the first alignment layer, that is, parallel to the XY plane. The first component of the incident light is parallel to the long axis of the liquid crystal molecules, and the second component is perpendicular to the long axis of the liquid crystal molecules. The liquid crystal optical rotation device 240 can make the two components produce a phase difference of half a wavelength, so that the outgoing light is rotated 90° relative to the polarization direction of the incident light. Figure 4 As shown, the polarization direction of the red backlight sub-beam after optical rotation is symmetrical to the polarization direction before optical rotation based on the alignment direction of the first alignment layer, and the polarization direction after optical rotation is parallel to the Y axis.

[0076] When powered on, it is in the first working mode, and the long axis of the liquid crystal molecules is perpendicular to the XY plane. At this time, the first component and the second component of the incident light are both perpendicular to the long axis of the liquid crystal molecules. Therefore, the phase difference generated by the liquid crystal optical rotation device 240 is 0, and the polarization direction of the light can be maintained. The polarization direction of the outgoing light is the same as that of the incident light.

[0077] Although, in the first working mode, a sufficiently large first control voltage is applied, during the time periods when backlights of different colors are turned on, the liquid crystal optical rotator 240 can make the long axis of the liquid crystal molecules perpendicular to the XY plane based on the same first control voltage, so that backlights of different wavelengths can maintain the polarization direction of the light. However, in the second working mode, when no power is applied, the second control voltage is 0. Since the phase difference corresponding to the optical rotation angle of the liquid crystal molecules is related to the wavelength of the incident light, when the red backlight sub-beam achieves a 90° optical rotation, the other two sub-beams cannot accurately achieve a 90° optical rotation. In order to solve this problem, the first optical rotator 24 can be set to include a plurality of liquid crystal optical rotators 240.

[0078] When the first optical rotator 24 includes a plurality of liquid crystal optical rotators 240, the liquid crystal optical rotators 240 in the first optical rotator 24 respectively rotate the polarization direction of the incident light by a corresponding angle based on the same rotation direction, and the angle is positively correlated with the first included angle, which is the included angle between the alignment direction of the first liquid crystal layer in the liquid crystal optical rotator and the polarization direction of the incident light of the liquid crystal optical rotator 240. In the first optical rotator 24, the liquid crystal optical rotator 240 respectively rotates the incident light by a corresponding angle based on the same incident direction, and the sum of the optical rotation angles of all the liquid crystal optical rotators 240 is equal to the above-mentioned set angle, which is (n-1)*180°+90°. The optical rotation angles corresponding to any two liquid crystal optical rotators 240 in the first optical rotator 24 are different.

[0079] The first optical rotator 24 includes a plurality of liquid crystal optical rotators 240. In the first mode, each liquid crystal optical rotator 240 can use the same first control voltage, so that the long axis of the liquid crystal molecules is perpendicular to the plane where the first optical rotator 24 is located, that is, perpendicular to the XY plane, so that each liquid crystal optical rotator 240 can maintain the polarization direction of the light. In the second mode, each liquid crystal optical rotator 240 can use the same second control voltage, and the second control voltage is 0 at this time, so that the long axis of the liquid crystal molecules is parallel to the plane where the first optical rotator 24 is located, and parallel to the alignment direction of the first liquid crystal layer, so that each incident light rotates a corresponding angle. In this way, each liquid crystal optical rotator 240 can control the working mode through the same first control voltage and the same second control voltage, and can accurately control the optical rotation angle of each color backlight sub-beam.

[0080] refer to Figure 5-Figure 7 As shown, Figure 5 A cross-sectional view of a first optical rotation device provided in an embodiment of the present application, Figure 6 for Figure 5 The schematic structural diagram of a liquid crystal optical rotator device in the first optical rotator device is shown, Figure 7 for Figure 5 The schematic diagram of the structure of another liquid crystal optical rotator in the first optical rotator is shown. In this embodiment, the first optical rotator 24 includes two liquid crystal optical rotators 240. In the XY coordinate system, the two liquid crystal optical rotators are the first liquid crystal optical rotator A1 and the second liquid crystal optical rotator A2 in the first direction Z, the XY plane is parallel to the plane where the first optical rotator 24 is located, and the polarization direction of the light incident on the first optical rotator 24 is parallel to the X axis.

[0081] like Figure 6 As shown, the alignment direction of the first liquid crystal layer 243 in the first liquid crystal optical rotation device 240 has an angle of 22.5° with the positive direction of the X axis; Figure 7As shown, the alignment direction of the first liquid crystal layer 243 in the second liquid crystal optical rotation device 240 has an angle of 67.5° with the positive direction of the X axis. The polarization direction of the light incident on the first optical rotation device 24 is parallel to the X axis. After being rotated by the first liquid crystal optical rotation device A1, the polarization direction after the rotation is about the polarization direction before the rotation. Figure 6 The alignment direction shown by the dotted line is symmetrical, so the polarization direction of the light emitted by the first liquid crystal optical rotator A1 after optical rotation has an angle of 45° with the X axis. Figure 7 The alignment direction shown by the dotted line has an angle of 22.5°. After the light passes through the second liquid crystal optical rotation device A2, the polarization direction of the outgoing light and the incident light are about Figure 7 The alignment direction shown by the dotted line is symmetrical, so the polarization direction of the light emitted by the second liquid crystal optical rotator device A2 is parallel to the Y axis. Figure 5-Figure 7 The first optical rotation device 24 shown is in the second working mode when no power is supplied, and can realize a 90° rotation of the polarization direction of light.

[0082] When the first optical rotator 24 has a plurality of liquid crystal optical rotators 240, the number of the liquid crystal optical rotators 240 and the alignment direction of the first liquid crystal layer 243 in each liquid crystal optical rotator 240 are not limited to Figure 5-Figure 7 As shown, based on the inventive concept of the present application, the number of liquid crystal rotator devices 240 and the alignment direction of the first liquid crystal layer 243 in each liquid crystal rotator device 240 can be set based on demand, so that in the second working mode, the polarization direction of the incident light and the outgoing light of the first rotator device 24 can be rotated by the required angle.

[0083] In other embodiments, the first optical rotation device 24 includes a Figure 4 In the liquid crystal optical rotator 240 shown, the alignment direction of the first liquid crystal layer 243 in the liquid crystal optical rotator 240 has an angle of 45° with the polarization direction of the incident light. The first optical rotator 24 is provided with a liquid crystal optical rotator 240, which can simplify the structure of the holographic display system and reduce its size in the first direction Z.

[0084] The backlight module 21 can emit a plurality of backlight sub-beams of different colors in time division. As mentioned above, the backlight module 21 can at least emit a red backlight sub-beam, a green backlight sub-beam, and a blue backlight sub-beam in time division.

[0085] Regardless of whether the first optical rotator 24 has a plurality of liquid crystal optical rotators 240 or a single liquid crystal optical rotator 240, when in the first working mode, during the time periods when backlight sub-beams of different colors are turned on, the controller is used to provide the same first control voltage to the liquid crystal optical rotator 240; when in the second working mode, during the time periods when backlight sub-beams of different colors are turned on, the controller is used to provide the same second control voltage to the liquid crystal optical rotator 240, and the second control voltage may be 0. In this manner, the long axis of the liquid crystal molecules in the liquid crystal optical rotator 240 can be controlled to be perpendicular to the XY plane in the first working mode by the same first control voltage, and the long axis of the liquid crystal molecules can be made parallel to the XY plane by the same second control voltage, and the control voltage timing of the liquid crystal optical rotator 240 is simple, and the control method is simple.

[0086] When the first optical rotation device 24 has a liquid crystal optical rotation device 240, as described above, in the second working mode, if all backlights of different colors use zero voltage as the second control voltage, the optical rotation angle will be inaccurate. At this time, it can be set that when in the first working mode, during the time period when the backlight sub-beams of different colors are turned on, the controller is used to provide the same first control voltage to the liquid crystal optical rotation device 240, so that the long axis of the liquid crystal molecules is perpendicular to the XY plane, so that all backlights of different colors can maintain the polarization direction of transmission in the first working mode; when in the second working mode, during the time period when the backlight sub-beams of different colors are turned on, the controller is used to provide different second control voltages to the liquid crystal optical rotation device. In the second working mode, each backlight of each color can have a corresponding second control voltage during the time period when the backlight is turned on, and the long axis of the liquid crystal molecules can be controlled to have an adaptive deflection angle relative to the alignment direction, so that all backlights of different colors can accurately rotate the set angle.

[0087] When the first optical rotator 24 has a liquid crystal optical rotator 240, the principle of adjusting the polarization direction of each color backlight in the first working mode and the second working mode is as follows: Figure 8-Figure 13 shown.

[0088] refer to Figure 8-Figure 13 As shown, Figure 8-Figure 13 A schematic diagram of the working principle of a liquid crystal optical rotation device provided in an embodiment of the present application. As mentioned above, the backlight module 21 can at least emit a red backlight sub-beam, a green backlight sub-beam, and a blue backlight sub-beam in a time-sharing manner.

[0089] Figure 8 A schematic diagram for illustrating the principle of the liquid crystal optical rotator 240 controlling the polarization direction of the blue backlight sub-beam, Fig. 9 A schematic diagram for illustrating the principle of controlling the polarization direction of the green backlight sub-beam by the liquid crystal optical rotator 240, Fig.10 A schematic diagram illustrating the principle of the liquid crystal optical rotator device 240 controlling the polarization direction of the red backlight sub-beam. Fig.11 for Figure 8 The schematic diagram of the liquid crystal molecule state in different working modes is shown. Fig.12 for Fig. 9 The schematic diagram of the liquid crystal molecule state in different working modes is shown. Fig.13 for Fig.10 The method shown is a schematic diagram of the state of liquid crystal molecules in different working modes. Figure 8-Figure 13 In the figure, the left figure is used to illustrate the deflection state of the liquid crystal molecules in the first working mode, and the right figure is used to illustrate the deflection state of the liquid crystal molecules in the second working mode. In the three-dimensional rectangular coordinate system XYZ, the first direction Z corresponds to the positive direction of the Z axis.

[0090] exist Figure 11-13 In the figure, the dotted line indicates the alignment direction of the first liquid crystal layer 243, and the dot-dash line indicates the long axis of the liquid crystal molecules. The alignment direction of the first liquid crystal layer 243 is controlled by the alignment direction of the first alignment layer. In the liquid crystal optical rotation device 240, the alignment directions of the two opposite first alignment layers are parallel.

[0091] When in the first working mode, the first working voltage of the liquid crystal optical rotation device 240 is set to be the first set voltage V0 during the blue backlight sub-beam on period, the green backlight sub-beam on period and the red backlight sub-beam on period. Figure 8-Figure 13 As shown in the middle left figure, the long axis of the liquid crystal molecule is perpendicular to the XY plane. The first set voltage V0 can be 20V.

[0092] When in the second working mode, the second control voltages corresponding to the blue backlight sub-beam on period, the green backlight sub-beam on period and the red backlight sub-beam on period are reduced in sequence, the second working voltage of the blue backlight sub-beam on period is the second set voltage Vb, the second working voltage of the green backlight sub-beam on period is the third set voltage Vg, and the second working voltage of the red backlight sub-beam on period is the fourth set voltage Vr. Among them, Vb>Vg>Vr. The fourth set voltage Vr can be 0.

[0093] like Figure 8-Figure 13In the middle right figure, based on Vb>Vg>Vr, the long axis of the liquid crystal molecule can be deflected by an angle of a1 relative to the alignment direction during the blue backlight sub-beam on period, and the vertical projection of the long axis of the liquid crystal molecule in the XY plane is parallel to the alignment direction; the long axis of the liquid crystal molecule can be deflected by an angle of a2 relative to the alignment direction during the green backlight sub-beam on period, and the vertical projection of the long axis of the liquid crystal molecule in the XY plane is parallel to the alignment direction; in the red backlight sub-beam on period, the long axis of the liquid crystal molecule has a 0° deflection relative to the alignment direction, and the long axis of the liquid crystal molecule is located in the XY plane and is parallel to the alignment direction. In this way, the second control voltage is negatively correlated with the backlight wavelength, so that the backlight sub-beams of different colors have the second control voltage of the adapted wavelength, so that each color backlight sub-beam can achieve accurate polarization direction rotation control.

[0094] refer to Fig.14 As shown, Fig.14 A schematic diagram of the structure of a liquid crystal grating module provided in an embodiment of the present application, wherein the liquid crystal grating module 23 comprises: a plurality of liquid crystal gratings 230 arranged in sequence in a first direction Z, and the alignment directions of the liquid crystal gratings 230 are different from each other. In the same liquid crystal grating module 23, a second optical rotation device 25 is provided between two adjacent liquid crystal gratings 230. In the same liquid crystal grating module 23, for any two adjacent liquid crystal gratings 230 in the first direction Z, the second optical rotation device 25 is used to rotate the polarization direction of the light emitted from the previous liquid crystal grating 230, so that the polarization direction of the light is parallel to the alignment direction of the next liquid crystal grating 230, or the polarization direction of the light is perpendicular to the alignment direction of the next liquid crystal grating 230.

[0095] In the same liquid crystal grating module 23, for any two adjacent liquid crystal gratings 230 in the first direction Z, the second optical rotation device 25 disposed between the two adjacent liquid crystal gratings 230 can control the polarization direction of the light incident on the next liquid crystal grating 230 to be perpendicular or parallel to the alignment direction of the next liquid crystal grating 230, so as to control whether the propagation direction of the light is deflected, so that within a set time period, at least one liquid crystal grating module 23 changes the propagation direction of the incident light, and at least one liquid crystal grating module 23 does not change the propagation direction of the incident light.

[0096] refer to Fig.15 As shown, Fig.15A schematic diagram of the structure of a liquid crystal grating provided in an embodiment of the present application, wherein the liquid crystal grating 230 includes: a first control electrode 231 and a second control electrode 232 arranged opposite to each other, wherein the first control electrode 231 is a transparent electrode layer of a whole layer, and the second control electrode 232 includes a plurality of strip electrodes arranged in parallel; and a second liquid crystal layer 233 located between the first control electrode 231 and the second control electrode 232. A second alignment layer is provided between the second liquid crystal layer 233 and the two control electrodes respectively, and the alignment direction of the second liquid crystal layer 233 is controlled by the alignment direction of the second alignment layer. In the liquid crystal grating 230, the alignment directions of the two opposite second alignment layers are parallel.

[0097] based on Fig.15 The liquid crystal grating 230 shown in FIG. 1 can make the refractive index of the second liquid crystal layer 233 as shown in FIG. 2 by controlling the voltage of the strip electrodes. Fig.15 The middle dashed curve shows a periodic change, and the refractive index of the second liquid crystal layer 233 has a plurality of alternating maxima and minima in a direction perpendicular to the extension direction of the strip electrodes, and the refractive index between adjacent maxima and minima changes continuously in sequence.

[0098] The polarization direction of the light incident on the liquid crystal grating 230 is controlled by the first optical rotation device 24. If the alignment direction of the liquid crystal grating 230 (i.e., the alignment direction of the second liquid crystal layer 233) is parallel to the polarization direction of the incident light, the propagation direction of the light can be deflected. If the alignment direction of the liquid crystal grating 230 is perpendicular to the polarization direction of the incident light, the propagation direction of the light can be maintained.

[0099] refer to Fig.16 As shown, Fig.16 The schematic diagram of the layout of a first optical rotator and a liquid crystal grating module provided in an embodiment of the present application, in which a first optical rotator 24 is provided on the light incident side of each liquid crystal grating module 23. Each liquid crystal grating module 23 is provided with a first optical rotator 24, and the polarization direction of the light incident on the corresponding liquid crystal grating module 23 can be independently controlled by the first optical rotator 24, and the propagation direction of the light can be selected to be transmitted without deflection or transmitted with deflection, and the control method is simple.

[0100] exist Fig.16In the illustrated manner, two liquid crystal grating modules 23 are used as an example for illustration, and a first optical rotation device 24 is correspondingly provided on the light incident side of each liquid crystal grating module 23. In the embodiment of the present application, the number of liquid crystal grating modules 23 in the holographic display system is not limited. The more the number of liquid crystal grating modules 23, the lower the image refresh frequency of the liquid crystal grating module 23 per unit time (such as 1s). In order to take into account the image refresh frequency of the liquid crystal grating module 23 and the size of the holographic display system in the first direction Z, the number of liquid crystal grating modules 23 is set to no more than , and preferably, the number of liquid crystal grating modules 23 is set to 2.

[0101] refer to Figure 17-Figure 19 As shown, Fig.17 A schematic diagram of the structure of a liquid crystal grating module provided in an embodiment of the present application, Fig.18 is a top view of each liquid crystal grating in a liquid crystal grating module with its alignment direction facing the first direction, Fig.19 is a top view of another liquid crystal grating module with each liquid crystal grating aligned in a first direction, Fig.18 and Fig.19 Corresponding to two liquid crystal grating modules 23 adjacent to each other in the first direction Z. Fig.18 and Fig.19 The top view is parallel to the XY plane; the second optical rotator 25 is a wave plate; the solid double-sided arrow in the liquid crystal grating 230 indicates the alignment direction of the liquid crystal grating 230, and the solid double-sided arrow in the second optical rotator 25 indicates the direction of the wave plate optical axis.

[0102] Fig.17 The liquid crystal grating module 23 shown has M liquid crystal gratings 230. In the same liquid crystal grating module 23, there is a second optical rotation device 25 between any two adjacent liquid crystal gratings 230. The M liquid crystal gratings are sequentially arranged from the first liquid crystal grating LCG1 to the Mth liquid crystal grating LCG in the first direction Z. M , M is a positive integer greater than 1. The more the number of liquid crystal gratings 230 in the liquid crystal grating module 23, the greater the range of adjustment of the light propagation direction deflection. In order to take into account the propagation range of the light propagation direction and the size of the holographic display system in the first direction Z, the number of liquid crystal gratings 230 is set to no more than 6, and M is preferably set to 3. Obviously, the value of M can be set based on demand and is not limited to Fig.17 In the manner shown as M=3, M can be set to any positive integer greater than 1.

[0103] When M = 3, Fig.18 and Fig.19As shown, in the same liquid crystal grating module 23, in the first direction Z, three continuously arranged liquid crystal gratings 230 are sequentially a first liquid crystal grating LCG1, a second liquid crystal grating LCG2, and a third liquid crystal grating LCG3. A first wave plate 251 serves as a second optical rotation device 25 located between the first liquid crystal grating LCG1 and the second liquid crystal grating LCG2. A second wave plate 252 serves as a second optical rotation device 25 located between the second liquid crystal grating LCG2 and the third liquid crystal grating LCG3.

[0104] Combination Figure 2 , Figure 16-Figure 19 As shown, for any two adjacent liquid crystal grating modules 23, the liquid crystal grating module 23 close to the spatial light modulator 22 (such as Fig.18 The i-th liquid crystal grating LCG i The orientation direction of the liquid crystal grating module 23 away from the spatial light modulator 22 (such as Fig.19 The M-i+1th liquid crystal grating LCG shown in FIG. M-i+1 The orientation directions are the same, i is a positive integer not greater than M. For any two adjacent liquid crystal grating modules 23, based on Fig.18 and Fig.19 The alignment direction correspondence shown can, when a first optical rotator 24 is separately provided in each liquid crystal grating module 23, independently control the polarization direction of the incident light corresponding to the liquid crystal grating module 23 through the first optical rotator 24, and select the light propagation direction to be transmitted without deflection or transmitted with deflection, and the control method is simple.

[0105] Each liquid crystal grating module 23 is provided with M liquid crystal gratings 230, so that the alignment directions of the liquid crystal gratings 230 in two adjacent liquid crystal grating modules 23 in the first direction Z can be correspondingly set, so as to control the polarization direction of the light incident on the liquid crystal grating module 23 through the first optical rotation device 24, thereby controlling whether the liquid crystal grating module 23 deflects the propagation direction of the light.

[0106] Optionally, the holographic display system has two liquid crystal grating modules 23 , and the liquid crystal grating module 23 has three liquid crystal gratings 230 , so as to take into account the size of the holographic display system in the first direction Z, the deflection adjustment range of the light propagation direction, and the image refresh frequency of the liquid crystal grating module 23 .

[0107] Combination Figure 2 and Fig.18As shown, the holographic display system has two adjacent liquid crystal grating modules 23. In the first direction Z, the alignment directions of the three liquid crystal gratings 230 in the liquid crystal grating module 23 close to the spatial light modulator 22 have angles of 0°, 45° and 135° with respect to the second direction, respectively. In the liquid crystal grating module 23, the optical axis of the first wave plate 251 has an angle of 22.5° with respect to the second direction, and the optical axis of the second wave plate 252 has an angle of 90° with respect to the second direction.

[0108] Combination Figure 2 and Fig.19 As shown, the alignment directions of the three liquid crystal gratings 230 in the liquid crystal grating module 23 far away from the spatial light modulator 22 have angles of 135°, 45° and 0° respectively relative to the second direction; in the liquid crystal grating module 23, the optical axis of the first wave plate 251 has an angle of 90° relative to the second direction, and the optical axis of the second wave plate 252 has an angle of 22.5° relative to the second direction. The polarization direction of the light emitted by the spatial light modulator 22 is the second direction, parallel to the X axis. Based on this method, it can be made Fig.18 The polarization direction of the light emitted from the liquid crystal grating module 23 is perpendicular or parallel to Fig.19 The first liquid crystal grating module 230 in the liquid crystal grating module 23 is aligned in a direction so as to facilitate Fig.19 The first optical rotation device 24 on the light incident side of the liquid crystal grating module 23 controls the liquid crystal grating module 23 to deflect the light propagation direction or maintain the light propagation direction.

[0109] refer to Fig. 20 As shown, Fig. 20 A schematic diagram of a layout of a liquid crystal grating module in a holographic display system provided in an embodiment of the present application, combined with Figure 2 and Fig. 20 As shown, the holographic display system at least includes a first liquid crystal grating module 23A and a second liquid crystal grating module 23B adjacently arranged in a first direction Z, and the first liquid crystal grating module 23A is located between the second liquid crystal grating module 23B and the spatial light modulator 22;

[0110] Combination Figure 17-Figure 20 As shown, the first liquid crystal grating module 23 and the second liquid crystal grating module 23 both have M liquid crystal gratings 230. In the same liquid crystal grating module 23, the M liquid crystal gratings 230 are sequentially arranged from the first liquid crystal grating LCG1 to the Mth liquid crystal grating LCG in the first direction Z. M , M is a positive integer greater than 1. The alignment of each liquid crystal grating 230 in the first liquid crystal grating module 23A can be as follows: Fig.18 As shown, the alignment direction of each liquid crystal grating 230 in the second liquid crystal grating module 23B can be as follows: Fig.19As shown, the i-th liquid crystal grating LCG in the first liquid crystal grating module 23A i The alignment direction is the same as the M-i+1th liquid crystal grating LCG in the second liquid crystal grating module 23B. M-i+1 The alignment direction of is the same, and i is a positive integer not greater than M. This method can make the polarization direction of the light emitted by the first liquid crystal grating module 23A and the alignment direction of the first liquid crystal grating LCG1 in the second liquid crystal grating module 23B in the first direction Z be parallel or perpendicular, so that the first optical rotation device 24 can control the working mode, so that at least one liquid crystal grating module 23 deflects the propagation direction of the light, and at least one liquid crystal grating module 23 does not deflect the propagation direction of the light.

[0111] When there are two liquid crystal grating modules 23 in the holographic display system, the liquid crystal grating 230 and the second optical rotation device 25 in the two liquid crystal grating modules 23 are respectively adopted as follows Fig.18 and Fig.19 In the manner shown, the principle of adjusting light in two adjacent monochromatic sub-images of the holographic display system can be as follows: Fig.21 and Fig. 22 shown.

[0112] refer to Fig.21 and Fig. 22 As shown, Fig.21 and Fig. 22 A schematic diagram of the principle of adjusting light in two adjacent frames of monochrome sub-images in a holographic display system provided in an embodiment of the present application. For two adjacent frames of monochrome sub-images, Fig.21 It is used to illustrate the light adjustment principle of the previous monochrome sub-image. Fig. 22 Used to illustrate the light adjustment principle of the next monochrome sub-image.

[0113] In the embodiment of the present application, the dotted double-sided arrow represents the polarization direction of the light, and the solid double-sided arrow in the spatial light modulator 22 represents its polarization direction; the first optical rotator 24 having a single liquid crystal optical rotator 240 is illustrated, and the solid double-sided arrow in the first optical rotator 24 represents the alignment direction of the liquid crystal optical rotator 240.

[0114] In addition, in the embodiment of the present application, the first optical rotation device 24 is defined as being in a closed state in the first working mode, and does not change the polarization direction of the light, and is in an open state in the second working mode, and changes the polarization direction of the light, so that the polarization direction of the light is rotated 90° before being emitted. When the polarization direction of the light is incident on each liquid crystal grating 230 in the liquid crystal grating module 23 in parallel, the propagation direction of the light is deflected after passing through the liquid crystal grating 230. When the polarization direction of the light is incident on each liquid crystal grating 230 in the liquid crystal grating module 23 in perpendicular order, the propagation direction of the light remains unchanged after passing through the liquid crystal grating 230, and the propagation direction of the light is not deflected.

[0115] like Fig.21 As shown, the first optical rotator 24A on the light incident side of the first liquid crystal grating module 23A is turned off, and the polarization direction of the light is not changed, and the polarization direction of the light emitted from the spatial light modulator 22 is kept incident on the first liquid crystal grating module 23A. In the first liquid crystal grating module 23A, the polarization direction of the light is incident on each liquid crystal grating 230 in sequence and in parallel, and the propagation direction of the light passing through the first liquid crystal grating module 23A is deflected. The first optical rotator 24B on the light incident side of the second liquid crystal grating module 23B is turned on, and the polarization direction of the light emitted from the first liquid crystal grating module 23A is rotated by 90°, and then incident on the second liquid crystal grating module 23B. In the second liquid crystal grating module 23B, the polarization direction of the light is incident on each liquid crystal grating 230 in sequence and in a vertical direction, and the propagation direction of the light passing through the second liquid crystal grating module 23B remains unchanged, and the propagation direction of the light is not deflected.

[0116] like Fig. 22 As shown, the first optical rotation device 24A on the light incident side of the first liquid crystal grating module 23A is turned on, and the polarization direction of the light is rotated by 90° before entering the first liquid crystal grating module 23A. In the first liquid crystal grating module 23A, the polarization direction of the light is incident on each liquid crystal grating 230 in sequence and perpendicularly, and the propagation direction of the light passing through the first liquid crystal grating module 23A remains unchanged, and the propagation direction of the light is not deflected. The first optical rotation device 24B on the light incident side of the second liquid crystal grating module 23B is turned on, and the polarization direction of the light emitted from the first liquid crystal grating module 23A is rotated by 90° before entering the second liquid crystal grating module 23B. In the second liquid crystal grating module 23B, the polarization direction of the light is incident on each liquid crystal grating 230 in sequence and parallelly, and the propagation direction of the light passing through the second liquid crystal grating module 23B is deflected.

[0117] exist Fig.21 and Fig. 22In the illustrated embodiment, the first liquid crystal grating module 23A deflects the propagation direction of light in each odd-numbered frame monochrome picture, and does not deflect the propagation direction of light in each even-numbered frame monochrome picture, and the second liquid crystal grating module 23B does not deflect the propagation direction of light in each odd-numbered frame monochrome picture, and deflects the propagation direction of light in each even-numbered frame monochrome picture. Among them, the first optical rotator 24A is in a closed state in each odd-numbered frame monochrome picture, and is in an open state in each even-numbered frame monochrome picture, and the first optical rotator 24B is in an open state in both odd-numbered frame monochrome pictures and even-numbered frame monochrome pictures.

[0118] refer to Fig.23 As shown, Fig.23 A schematic diagram of another layout of the first optical rotation device and the liquid crystal grating module provided in the embodiment of the present application, combined with Figure 2 , Fig.17 and Fig.23 As shown, the holographic display system has a first optical rotator 24, and the first optical rotator 24 is arranged on the light incident side of the liquid crystal grating module 23 adjacent to the spatial light modulator 22. In this mode, based on the alignment direction of the liquid crystal gratings 230 in each liquid crystal grating module 23 and the matching arrangement of the optical axis direction of the second optical rotator 25, the first optical rotator 24 can change the propagation direction of the incident light within a set time period, and at least one liquid crystal grating module 23 does not change the propagation direction of the incident light. The number of the first optical rotator 24 is minimal, and the size of the holographic display system in the first direction Z is reduced.

[0119] When the holographic display system has a first optical rotation device 24, as described above, the liquid crystal grating module 23 is provided with M liquid crystal gratings 230, and the M liquid crystal gratings 230 are sequentially from the first liquid crystal grating LCG1 to the Mth liquid crystal grating LCG in the first direction Z. M , M is a positive integer greater than 1. At this time, the alignment directions of the liquid crystal gratings in two adjacent liquid crystal grating modules 23 can be as follows: Fig.24 shown.

[0120] refer to Fig.24 As shown, Fig.24 It is a top view of the alignment direction of each liquid crystal grating in two adjacent liquid crystal grating modules toward the first direction, and the top view is parallel to the XY plane.

[0121] exist Fig.24 In the manner shown, for any two adjacent liquid crystal grating modules 23, in the first direction Z, the combination Figure 2 and Fig.24 As shown, the i-th liquid crystal grating LCG in the liquid crystal grating module 23 (first liquid crystal grating module 23A) close to the spatial light modulator 22 iThe alignment direction is the same as the M-i+1th liquid crystal grating LCG in the liquid crystal grating module 23 (the second liquid crystal grating module 23B) far away from the spatial light modulator 22. M-i+1 The alignment direction is centrally symmetrical and the Mth liquid crystal grating LCG in the liquid crystal grating module 23 close to the spatial light modulator 22 M The alignment direction of is perpendicular to the alignment direction of the first liquid crystal grating LCG1 in the liquid crystal grating module 23 far away from the spatial light modulator 22 , and i is a positive integer not greater than M.

[0122] In the first direction Z, the i-th liquid crystal grating LCG in the first liquid crystal grating module 23A is arranged i The alignment direction is the same as the M-i+1th liquid crystal grating LCG in the second liquid crystal grating module 23B. M-i+1 The orientation direction is centrally symmetrical, so if all the liquid crystal gratings 230 are arranged in a straight line in a plane based on the arrangement order in the first direction Z, the i-th liquid crystal grating LCG in the first liquid crystal grating module 23A is i The alignment direction is the same as the M-i+1th liquid crystal grating LCG in the second liquid crystal grating module 23B. M-i+1 The alignment direction is symmetrical about an axis perpendicular to the straight line.

[0123] use Fig.24 The method shown can control whether each liquid crystal grating module 23 deflects the propagation direction of the incident light through a first optical rotation device 24. Compared with the solution of separately setting a first optical rotation device 24 for each liquid crystal grating module 23, the size of the holographic display system in the first direction Z is reduced.

[0124] Combination Figure 2 and Fig.24 As shown, when the holographic display system has a first optical rotation device 24, the holographic display system can be configured to have two liquid crystal grating modules 23 as described above, and the liquid crystal grating module 23 has three liquid crystal gratings. In the first direction Z, the alignment directions of the three liquid crystal gratings 230 in the liquid crystal grating module 23 (first liquid crystal grating module 23A) close to the spatial light modulator 22 have angles of 0°, 45° and 135° with respect to the second direction, respectively, and the alignment directions of the three liquid crystal gratings 230 in the liquid crystal grating module 23 (second liquid crystal grating module 23B) far from the spatial light modulator 22 have angles of 45°, 135° and 0° with respect to the second direction, respectively; wherein the polarization direction of the light emitted from the spatial light modulator 22 is the second direction.

[0125] like Fig.24As shown, in the first liquid crystal grating module 23A, the optical axis of the first wave plate 251 has an angle of 22.5° relative to the second direction, and the optical axis of the second wave plate 252 has an angle of 90° relative to the second direction; in the second liquid crystal grating module 23B, the optical axis of the first wave plate 251 has an angle of 90° relative to the second direction, and the optical axis of the second wave plate 252 has an angle of 45° relative to the second direction.

[0126] use Fig.24 The illustrated method corresponds to setting the alignment direction of each liquid crystal grating 230 in two adjacent liquid crystal grating modules 23 and the optical axis direction of the second optical rotation device 25, so that the holographic display system can control whether each liquid crystal grating module 23 deflects the propagation direction of the incident light through a first optical rotation device 24, thereby reducing the size of the holographic display system in the first direction Z.

[0127] Optionally, in the holographic display system provided in the embodiment of the present application, the second optical rotation device 25 is a half-wave plate. The optical axis direction of the half-wave plate is adapted to the alignment direction of the adjacent liquid crystal gratings 230, so that the alignment direction of the transmitted light in the liquid crystal grating module 230 is parallel to the alignment direction of each liquid crystal grating 230 or perpendicular to the alignment direction of each liquid crystal grating 230.

[0128] In the first direction Z, for two adjacent liquid crystal grating modules 23, the alignment direction of the last liquid crystal grating 230 in the liquid crystal grating module 23 close to the spatial light modulator 22 is set to be perpendicular or parallel to the alignment direction of the first liquid crystal grating 230 in the liquid crystal grating module 23 away from the spatial light modulator 22, so that at least one liquid crystal grating module 23 changes the propagation direction of the incident light and at least one liquid crystal grating module 23 does not change the propagation direction of the incident light in a set time period through the first optical rotation device 24.

[0129] exist Fig.24 In the illustrated embodiment, the alignment direction of the 13th liquid crystal grating LCG3 in the first liquid crystal grating module 23A is perpendicular to the alignment direction of the 1st liquid crystal grating LCG1 in the second liquid crystal grating module 23B. Fig.24 The principle of adjusting light in two adjacent monochromatic sub-images of the holographic display system can be as follows: Fig.25 and Fig.26 shown.

[0130] refer to Fig.25 and Fig.26 As shown, Fig.25 and Fig.26 A schematic diagram of the principle of adjusting light in two adjacent frames of monochrome sub-images in another holographic display system provided in an embodiment of the present application. For two adjacent frames of monochrome sub-images, Fig.25 It is used to illustrate the principle of adjusting the light of the previous frame of monochrome sub-image. Fig.26 It is used to illustrate the principle of adjusting light of the next monochrome sub-image.

[0131] according to Fig.25 and Fig.26 As shown, using Fig.24 The illustrated method can also enable the first liquid crystal grating module 23A and the second liquid crystal grating module 23B to alternately deflect the propagation direction of light, thereby reducing the image refresh frequency of the liquid crystal grating module 23 .

[0132] In the embodiment of the present application, at the same time, one liquid crystal grating 230 changes the propagation direction of the incident light, and the other liquid crystal gratings maintain the propagation direction of the incident light; within a set time period, the backlight module 21 refreshes the backlight beam at a first frequency, and the liquid crystal grating module 23 changes the propagation direction of the incident light at a second frequency, the first frequency is N times the second frequency, and N is the number of liquid crystal grating modules 23 in the holographic display system.

[0133] for Figure 1 In the single liquid crystal grating module 13 holographic display system shown, if the first frequency is 360 Hz, the liquid crystal grating module 13 needs to refresh the monochrome sub-image 360 ​​times within 1 second, that is, the second frequency is also 360 Hz, and the first frequency is equal to the second frequency.

[0134] In the holographic display system with N liquid crystal grating modules 23 provided in the embodiment of the present application, if the first frequency is 360 Hz, it is only necessary to make the N liquid crystal grating modules 23 jointly realize 360 ​​refreshes of the monochrome sub-images. The refresh of the second monochrome sub-image, at this time the second frequency is Hz, at this time the first frequency is equal to N times the second frequency, that is, the second frequency is only 1 / N of the first frequency.

[0135] The following is a comparison of the timing diagram to illustrate the present application scheme relative to Figure 1 The scheme shown is used to illustrate the effect of reducing the image refresh frequency of the liquid crystal grating module 23 .

[0136] refer to Fig. 27 As shown, Fig. 27 for Figure 1 The timing diagram of the holographic display system shown in FIG. Figure 1 and Fig. 27As shown, for the j-th frame image and the j+1-th frame image that are adjacent in time sequence, the j-th frame image and the j+1-th frame image both have a red light sub-image, a green light sub-image, and a blue light sub-image. j is a positive integer greater than 1. In one frame image cycle, the backlight module 11 needs to turn on the red light (R), green light (G), and blue light (B) in a time-sharing manner; the spatial light modulator 12 needs 1 / 3 of a frame image cycle for each color backlight to complete the scanning of the corresponding color backlight; the liquid crystal grating module 13 needs 1 / 3 of a frame image cycle for each color backlight to complete the data writing of the corresponding color backlight and the post-deflection stabilization process of the liquid crystal molecules.

[0137] based on Fig. 27 It can be seen that if the backlight module 11 has 360 backlight on periods in 1 second, the corresponding backlight operating frequency is 360 Hz, and the liquid crystal grating module 13 corresponds to 360 backlight data writing and liquid crystal molecules stabilization processes after deflection, that is, the image refresh frequency of the liquid crystal grating module 13 is 360 Hz. The image refresh frequency of the liquid crystal grating module 13 is the same as the backlight operating frequency. The liquid crystal grating module 13 operates at 360 Hz, and the time for the liquid crystal grating to charge and the liquid crystal molecules to flip in the liquid crystal grating module 13 is extremely short.

[0138] refer to Fig.28 As shown, Fig.28 The timing diagram of the holographic display system provided in the embodiment of the present application is combined with Figure 2 , Fig.23 and Fig.28 As shown, the holographic display system has a first optical rotation device 24 and two liquid crystal grating modules 23. For the j-th frame image and the j+1-th frame image that are adjacent in time sequence, the j-th frame image and the j+1-th frame image both have a red light sub-image, a green light sub-image and a blue light sub-image. Similarly, within a frame image cycle, the backlight module 21 needs to turn on the red light (R), green light (G) and blue light (B) in a time-sharing manner; the spatial light modulator 22 requires 1 / 3 of a frame image cycle for each color backlight to complete the scanning of the corresponding color backlight. The difference is that within 2 frame image cycles, the RGB three-color backlight only needs one data writing and a post-deflection stabilization process of the liquid crystal molecules. If the backlight module 21 operates at 360Hz, each liquid crystal grating module 23 only needs to operate at 180Hz, which greatly reduces the difficulty of device design and driving.

[0139] based on Fig.28 As shown, the operating frequency of the first optical rotation device 24 is twice the image refresh frequency of the liquid crystal grating module 23 .

[0140] and Fig.28The method shown can greatly increase the duration of the post-deflection stabilization process of the liquid crystal molecules, and can perform light deflection control after the liquid crystal molecules are completely stable, thereby improving the accuracy of light deflection control.

[0141] Based on the above description, it can be known that by setting N liquid crystal grating modules 23, the image refresh frequency of the liquid crystal grating module 23 can be reduced to Figure 1 Taking the backlight module 21 operating at 360 Hz as an example, if N=2, the image refresh frequency of the liquid crystal grating module 23 can be reduced to 180 Hz, and if N=3, the image refresh frequency of the liquid crystal grating module 23 can be reduced to 120 Hz.

[0142] refer to Fig.29 As shown, Fig.29 A schematic diagram of another structure of a holographic display system provided in an embodiment of the present application, in which the holographic display system has three liquid crystal grating modules 23, and the light incident side of each liquid crystal grating module 23 corresponds to a first optical rotation device 24. As mentioned above, taking into account the size of the holographic display system in the first direction Z and the frequency reduction requirement of the liquid crystal grating module 23, the number of the liquid crystal grating modules 23 in the holographic display system is selected to be 2 or 3, and the embodiment of the present application does not limit this.

[0143] Optionally, a field lens may be provided between the spatial light modulator 22 and the adjacent liquid crystal grating module 23, and the first optical rotation device 24 and the liquid crystal grating module 23 are both located on the side of the scene away from the spatial light modulator 22. The field lens is used to improve the ability of the edge light of the light emitted by the spatial light modulator 22 to enter the liquid crystal grating module 23.

[0144] It can be seen from the above description that in the holographic display system provided by the technical solution of the present application, at least one first optical rotation device 24 is provided to switch the polarization direction of the light in two orthogonal directions during the display process, so that in a set time period, at least one liquid crystal grating module 23 changes the propagation direction of the incident light, and at least one liquid crystal grating module 23 does not change the propagation direction of the incident light, thereby reducing the image refresh frequency of the liquid crystal grating module 23. The holographic display system has at least two liquid crystal grating modules 23, which perform deflection control of the propagation direction of the light in a time-sharing manner, and whether the liquid crystal grating module 23 deflects the propagation direction of the light is controlled by the first optical rotation device 24, such as the control of the polarization direction of the light.

[0145] Based on the above embodiment, another embodiment of the present application further provides a holographic display method based on the above holographic display system. The holographic display method is as follows: Fig.30 shown.

[0146] refer to Fig.30 As shown, Fig.30A schematic flow chart of a holographic display method provided in an embodiment of the present application, the holographic display method comprising:

[0147] Step S11: emitting a backlight beam through the backlight module;

[0148] Step S12: performing phase modulation and amplitude modulation on the backlight beam through a spatial light modulator;

[0149] Step S13: Based on the first optical rotation device, at least one liquid crystal grating module changes the propagation direction of the incident light within a set time period, and at least one liquid crystal grating module does not change the propagation direction of the incident light.

[0150] In the holographic display method, the implementation principle of whether the liquid crystal grating module changes the propagation direction of the incident light has been described with reference to the above embodiment and will not be repeated in this embodiment.

[0151] The holographic display method can be implemented based on the above holographic display system, which greatly reduces the image refresh frequency of the liquid crystal grating module.

[0152] Based on the above embodiment, another embodiment of the present application further provides an electronic device. Fig.31 shown.

[0153] refer to Fig.31 , Fig.31 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application, wherein the electronic device 41 includes a holographic display system, and the holographic display system can adopt any of the above-mentioned methods in the above-mentioned examples.

[0154] The electronic device can be a mobile phone, computer, wearable device, television, vehicle-mounted display device, or other electronic product with display function. The electronic device adopts the holographic display system provided by any of the above methods in the above examples, which can greatly reduce the screen refresh frequency of the liquid crystal grating module.

[0155] In this specification, each embodiment is described in a progressive, parallel, or progressive and parallel manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the electronic device and holographic display method disclosed in the embodiment, since they correspond to the holographic display method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the corresponding part of the holographic display method.

[0156] It should be noted that in the description of the present application, it should be understood that the description of the drawings and embodiments is illustrative rather than restrictive. The same drawings throughout the embodiments of the specification mark the same structure. In addition, for the sake of understanding and ease of description, the drawings may exaggerate the thickness of some layers, films, panels, regions, etc. It is also understood that when an element such as a layer, film, region or substrate is referred to as "on" another element, the element may be directly on the other element or there may be an intermediate element. In addition, "on" refers to positioning an element on or below another element, but does not essentially mean positioning on the upper side of another element according to the direction of gravity.

[0157] The terms "upper", "lower", "top", "bottom", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. When a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0158] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the article or device including the above elements.

[0159] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A holographic display system, characterized in that: include: A backlight module, a spatial light modulator and a plurality of liquid crystal grating modules are sequentially arranged in a first direction; The backlight module is used to emit a backlight beam; The spatial light modulator is used to perform phase modulation and amplitude modulation on the backlight beam; A plurality of the liquid crystal grating modules are arranged in sequence in the first direction; based on the polarization direction of the incident light, the liquid crystal grating module can change the propagation direction of the incident light or maintain the propagation direction of the incident light; Among them, at least one of the liquid crystal grating modules has a first optical rotation device on the light incident side, and the first optical rotation device can rotate the polarization direction of the incident light, so that in a set time period, at least one of the liquid crystal grating modules changes the propagation direction of the incident light, and at least one of the liquid crystal grating modules does not change the propagation direction of the incident light.

2. The holographic display system according to claim 1, characterized in that: The first optical rotation device has a first working mode and a second working mode; In the first working mode, the first optical rotator can allow the incident light to pass through while maintaining its polarization direction; In the second working mode, the first optical rotator can rotate the polarization direction of the incident light by (n-1)*180°+90° before transmitting the light, where n is a positive integer and the direction of the rotation axis is perpendicular to the plane where the first optical rotator is located.

3. The holographic display system according to claim 2, characterized in that: The first optical rotation device comprises: at least one liquid crystal optical rotation device; the liquid crystal optical rotation device comprises: a first electrode layer and a second electrode layer arranged opposite to each other; a first liquid crystal layer located between the first electrode layer and the second electrode layer; The holographic display system comprises a controller, wherein the controller is connected to the electrode layer of the liquid crystal optical rotation device; in the first working mode, the controller is used to provide a first control voltage to the first electrode layer and the second electrode layer so that the long axis of the liquid crystal molecules is perpendicular to the plane where the first optical rotation device is located; in the second working mode, the controller is used to provide a second control voltage to the first electrode layer and the second electrode layer so that the long axis of the liquid crystal molecules has an angle of not less than 0° and less than 90° with the plane where the first optical rotation device is located; wherein the first control voltage is different from the second control voltage.

4. The holographic display system according to claim 3, characterized in that: The first optical rotator device includes a plurality of liquid crystal optical rotators; The liquid crystal optical rotator device rotates the polarization direction of the incident light by a set angle based on the same rotation direction. The set angle is positively correlated with a first angle, which is the angle between the alignment direction of the first liquid crystal layer and the polarization direction of the incident light of the liquid crystal optical rotator device.

5. The holographic display system according to claim 3, characterized in that: The first optical rotator device includes two liquid crystal optical rotators, and the two liquid crystal optical rotators are sequentially a first liquid crystal optical rotator device and a second liquid crystal optical rotator device in the first direction; In an XY coordinate system, an XY plane is parallel to the plane where the first optical rotator is located, and the polarization direction of the light incident on the first optical rotator is parallel to the X-axis; the alignment direction of the first liquid crystal layer in the first liquid crystal optical rotator is at an angle of 22.5° with the positive direction of the X-axis, and the alignment direction of the first liquid crystal layer in the second liquid crystal optical rotator is at an angle of 67.5° with the positive direction of the X-axis.

6. The holographic display system according to claim 3, characterized in that: The first optical rotation device includes a liquid crystal optical rotation device, and the alignment direction of the first liquid crystal layer and the polarization direction of the incident light have an angle of 45°.

7. The holographic display system according to any one of claims 3 to 6, characterized in that: The backlight module can emit a plurality of backlight sub-beams of different colors in different time periods; When in the first working mode, during the time periods when the backlight sub-beams of different colors are turned on, the controller is used to provide the same first control voltage to the liquid crystal optical rotation device; When in the second working mode, during the on-time periods of the backlight sub-beams of different colors, the controller is used to provide the same second control voltage to the liquid crystal optical rotation device.

8. The holographic display system according to claim 6, characterized in that: The backlight module can emit a plurality of backlight sub-beams of different colors in different time periods; When in the first working mode, during the time periods when the backlight sub-beams of different colors are turned on, the controller is used to provide the same first control voltage to the liquid crystal optical rotation device; When in the second working mode, during the on-time period of the backlight sub-beam backlights of different colors, the controller is used to provide different second control voltages for the liquid crystal optical rotation device.

9. The holographic display system according to claim 8, characterized in that: The backlight module is capable of emitting at least a red backlight sub-beam, a green backlight sub-beam, and a blue backlight sub-beam in a time-sharing manner; When in the second working mode, the second control voltages corresponding to the blue backlight sub-beam on period, the green backlight sub-beam on period and the red backlight sub-beam on period are reduced in sequence.

10. The holographic display system according to claim 1, characterized in that: The liquid crystal grating module comprises: a plurality of liquid crystal gratings arranged in sequence in the first direction, wherein the alignment directions of the liquid crystal gratings are different from each other; In the same liquid crystal grating module, a second optical rotation device is provided between two adjacent liquid crystal gratings; In the same liquid crystal grating module, for any two adjacent liquid crystal gratings in the first direction, the second optical rotation device is used to rotate the polarization direction of the light emitted from the previous liquid crystal grating, so that the polarization direction of the light is parallel to the alignment direction of the next liquid crystal grating, or so that the polarization direction of the light is perpendicular to the alignment direction of the next liquid crystal grating.

11. The holographic display system according to claim 10, characterized in that: The light incident side of the liquid crystal grating module is provided with the first optical rotation device.

12. The holographic display system according to claim 11, characterized in that: The liquid crystal grating module has M liquid crystal gratings, and the M liquid crystal gratings are sequentially from the first liquid crystal grating to the Mth liquid crystal grating in the first direction, and M is a positive integer greater than 1; For any two adjacent liquid crystal grating modules, the alignment direction of the i-th liquid crystal grating in the liquid crystal grating module close to the spatial light modulator is the same as the alignment direction of the M-i+1-th liquid crystal grating in the liquid crystal grating module far from the spatial light modulator, and i is a positive integer not greater than M.

13. The holographic display system according to claim 12, characterized in that: There are two liquid crystal grating modules, and the liquid crystal grating module has three liquid crystal gratings; In the first direction, the alignment directions of the three liquid crystal gratings in the liquid crystal grating module close to the spatial light modulator have angles of 0°, 45° and 135° respectively relative to the second direction, and the alignment directions of the three liquid crystal gratings in the liquid crystal grating module far from the spatial light modulator have angles of 135°, 45° and 0° respectively relative to the second direction; wherein the polarization direction of the light emitted by the spatial light modulator is the second direction.

14. The holographic display system according to any one of claims 1 or 10, characterized in that: The holographic display system at least includes a first liquid crystal grating module and a second liquid crystal grating module disposed adjacent to each other in the first direction, wherein the first liquid crystal grating module is located between the second liquid crystal grating module and the spatial light modulator; The first liquid crystal grating module and the second liquid crystal grating module both have M liquid crystal gratings. In the same liquid crystal grating module, the M liquid crystal gratings are sequentially from the first liquid crystal grating to the Mth liquid crystal grating in the first direction, where M is a positive integer greater than 1. The alignment direction of the i-th liquid crystal grating in the first liquid crystal grating module is the same as the alignment direction of the M-i+1-th liquid crystal grating in the second liquid crystal grating module, and i is a positive integer not greater than M.

15. The holographic display system according to claim 10, characterized in that: The first optical rotator is provided on the light incident side of the liquid crystal grating module adjacent to the spatial light modulator.

16. The holographic display system according to claim 15, characterized in that: The liquid crystal grating module has M liquid crystal gratings, and the M liquid crystal gratings are sequentially from the first liquid crystal grating to the Mth liquid crystal grating in the first direction, and M is a positive integer greater than 1; For any two adjacent liquid crystal grating modules, in the first direction, the alignment direction of the i-th liquid crystal grating in the liquid crystal grating module close to the spatial light modulator is centrally symmetric with the alignment direction of the M-i+1-th liquid crystal grating in the liquid crystal grating module far from the spatial light modulator, and the alignment direction of the M-th liquid crystal grating in the liquid crystal grating module close to the spatial light modulator is perpendicular to the alignment direction of the 1st liquid crystal grating in the liquid crystal grating module far from the spatial light modulator, and i is a positive integer not greater than M.

17. The holographic display system according to claim 16, characterized in that: There are two liquid crystal grating modules, and the liquid crystal grating module has three liquid crystal gratings; In the first direction, the alignment directions of the three liquid crystal gratings in the liquid crystal grating module close to the spatial light modulator have angles of 0°, 45° and 135° respectively relative to the second direction, and the alignment directions of the three liquid crystal gratings in the liquid crystal grating module far from the spatial light modulator have angles of 45°, 135° and 0° respectively relative to the second direction; wherein the polarization direction of the light emitted by the spatial light modulator is the second direction.

18. The holographic display system according to claim 11, characterized in that: The second optical rotation device is a half-wave plate.

19. The holographic display system according to claim 1, characterized in that: At the same time, one of the liquid crystal grating modules changes the propagation direction of the incident light, while the other liquid crystal grating modules maintain the propagation direction of the incident light; During the set time period, the backlight module refreshes the backlight beam at a first frequency, and the liquid crystal grating module changes the propagation direction of the incident light at a second frequency. The first frequency is N times the second frequency, and N is the number of liquid crystal grating modules in the holographic display system.

20. A holographic display method based on the holographic display system according to any one of claims 1 to 19, characterized in that: include: Emits a backlight beam through the backlight module; Performing phase modulation and amplitude modulation on the backlight beam by means of the spatial light modulator; Based on the first optical rotation device, within a set time period, at least one of the liquid crystal grating modules changes the propagation direction of the incident light, and at least one of the liquid crystal grating modules does not change the propagation direction of the incident light.

21. An electronic device, characterized in that: Comprising a holographic display system as described in any one of claims 1-19.

Images