A liquid crystal grating and a stereoscopic display device

Abstract

The present invention provides a liquid crystal grating and a stereoscopic display device. The liquid crystal grating includes a first substrate, a second substrate, and a liquid crystal layer, and the liquid crystal layer is located between the first substrate and the second substrate; a plurality of grating units arranged along a first direction, including a plurality of first electrodes and a plurality of second electrodes; a plurality of the first electrodes are located between the first substrate and the liquid crystal layer and are spaced apart from each other along the first direction; a plurality of the second electrodes are located between the second substrate and the liquid crystal layer and are spaced apart from each other along the first direction; there are at least two of the first electrodes having different voltages, and there are at least two of the second electrodes having different voltages. The present invention provides a liquid crystal grating and a stereoscopic display device to achieve reducing the transverse electric field intensity of a single substrate, reducing the adverse effect of the transverse electric field on the rotation of liquid crystal molecules, and improving the reverse domain problem.

Description

Technical Field

[0001] The present invention relates to the field of display technologies, and particularly to a liquid crystal grating and a stereoscopic display device. Background Art

[0002] Since two-dimensional displays are difficult to clearly and accurately express three-dimensional depth information, people have been committed to researching display technologies that can display stereoscopic scenes - three-dimensional image display technologies. Holographic three-dimensional display technology uses the diffraction or interference of light to record the amplitude and phase information of object light, and then reconstructs the information of object light through the diffraction of light. It is the only truly three-dimensional display technology among various display methods.

[0003] When a stereoscopic display device performs three-dimensional image display, after a spatial light modulator (SLM) modulates the optical signal in terms of phase and amplitude, generally, left-eye and right-eye images are formed through the diffraction function of a liquid crystal grating. How to improve the display effect has become an urgent problem to be solved. Summary of the Invention

[0004] The present invention provides a liquid crystal grating and a stereoscopic display device to reduce the lateral electric field intensity of a single substrate, reduce the adverse effects of the lateral electric field on the rotation of liquid crystal molecules, and improve the reverse domain problem.

[0005] In a first aspect, an embodiment of the present invention provides a liquid crystal grating, including a first substrate, a second substrate, and a liquid crystal layer, where the liquid crystal layer is located between the first substrate and the second substrate;

[0006] A plurality of grating units, arranged along a first direction, including a plurality of first electrodes and a plurality of second electrodes; a plurality of the first electrodes are located between the first substrate and the liquid crystal layer, and are spaced apart from each other along the first direction; a plurality of the second electrodes are located between the second substrate and the liquid crystal layer, and are spaced apart from each other along the first direction;

[0007] There are at least two of the first electrodes having different voltages, and there are at least two of the second electrodes having different voltages.

[0008] In a second aspect, an embodiment of the present invention provides a stereoscopic display device, including a light source, a spatial light modulator, and a grating assembly arranged in sequence;

[0009] The grating assembly includes at least one liquid crystal grating as described in the first aspect.

[0010] In the liquid crystal grating provided by the embodiment of the present invention, there are at least two first electrodes with different voltages, and a transverse electric field is generated between the first electrodes. There are at least two second electrodes with different voltages, and a transverse electric field is generated between the second electrodes. Thus, the transverse electric field is dispersed between the first electrodes and the second electrodes, and between the first substrate and the second substrate, rather than concentrated on one substrate (the substrate includes the first substrate and the second substrate), thereby reducing the transverse electric field strength of a single substrate. The adverse effect of the transverse electric field on the rotation of liquid crystal molecules is reduced, and the reverse domain problem is improved. Description of the Drawings

[0011] Figure 1 Schematic cross-sectional structure diagram of a liquid crystal grating in the prior art;

[0012] Figure 2 Schematic diagram of the voltage distribution of the first electrode and the second electrode in the prior art;

[0013] Figure 3 Schematic top view structure diagram of a liquid crystal grating provided by the embodiment of the present invention;

[0014] Figure 4 Along Figure 3 Cross-sectional structure diagram in the AA' direction in;

[0015] Figure 5 Schematic diagram of an electric field formed by a first voltage difference provided by the embodiment of the present invention;

[0016] Figure 6 Schematic diagram of a first voltage difference provided by the embodiment of the present invention;

[0017] Figure 7 Schematic diagram of another first voltage difference provided by the embodiment of the present invention;

[0018] Figure 8 Schematic diagram of another first voltage difference provided by the embodiment of the present invention;

[0019] Figure 9 Schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention;

[0020] Figure 10 Schematic diagram of another voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention;

[0021] Figure 11 Schematic diagram of another voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention;

[0022] Figure 12 Schematic cross-sectional structure diagram of another liquid crystal grating provided by the embodiment of the present invention;

[0023] Figure 13 Another schematic diagram of the voltage distribution of the first electrode provided by the embodiment of the present invention;

[0024] Figure 14 Another schematic diagram of the voltage distribution of the second electrode provided by the embodiment of the present invention;

[0025] Figure 15 Another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention;

[0026] Figure 16 Another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention;

[0027] Figure 17 Another schematic diagram of the first voltage difference provided by the embodiment of the present invention;

[0028] Figure 18 Another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention;

[0029] Figure 19 Another schematic diagram of the first voltage difference provided by the embodiment of the present invention;

[0030] Figure 20 Another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention;

[0031] Figure 21 Another schematic diagram of the first voltage difference provided by the embodiment of the present invention;

[0032] Figure 22 Another schematic diagram of the sectional structure of the liquid crystal grating provided by the embodiment of the present invention;

[0033] Figure 23 Another schematic diagram of the sectional structure of the liquid crystal grating provided by the embodiment of the present invention;

[0034] Figure 24 Another schematic diagram of the sectional structure of the liquid crystal grating provided by the embodiment of the present invention;

[0035] Figure 25 Another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention;

[0036] Figure 26 Another schematic diagram of the sectional structure of the liquid crystal grating during the inventor's research process;

[0037] Figure 27 Another schematic diagram of the voltage distribution of the first electrode and the second electrode of the liquid crystal grating during the inventor's research process;

[0038] Figure 28 Another cross-sectional structure diagram of a liquid crystal grating provided by an embodiment of the present invention;

[0039] Figure 29 Another voltage distribution diagram of the first electrode and the second electrode of a liquid crystal grating provided by an embodiment of the present invention;

[0040] Figure 30 Another three-dimensional structure diagram of a liquid crystal grating provided by an embodiment of the present invention;

[0041] Figure 31 Another working process diagram of a liquid crystal grating provided by an embodiment of the present invention;

[0042] Figure 32 Another working process diagram of a liquid crystal grating provided by an embodiment of the present invention;

[0043] Figure 33 Another working timing diagram of a liquid crystal grating provided by an embodiment of the present invention;

[0044] Figure 34 A schematic diagram of a three-dimensional display device provided by an embodiment of the present invention. Detailed implementation manners

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only parts related to the present invention rather than all structures are shown in the accompanying drawings.

[0046] Figure 1 A cross-sectional structure diagram of a liquid crystal grating during the inventor's research process, referring to Figure 1 , the liquid crystal grating includes a first substrate 11, a second substrate 12, and a liquid crystal layer 30. The liquid crystal layer 30 is located between the first substrate 11 and the second substrate 12. The liquid crystal layer 30 includes liquid crystal molecules. The liquid crystal grating includes a plurality of grating units 40. The plurality of grating units 40 are arranged along the first direction X. The grating unit 40 includes a plurality of first electrodes 21 and one second electrode 22. The plurality of first electrodes 21 are located between the first substrate 11 and the liquid crystal layer 30. The plurality of first electrodes 21 are spaced apart from each other along the first direction X. Along the first direction X, there is a certain distance between two adjacent first electrodes 21. The plurality of grating units 40 share the same second electrode 22, and the second electrode 22 is a full-surface electrode.

[0047] Figure 2 A voltage distribution diagram of the first electrode and the second electrode of a liquid crystal grating during the inventor's research process, referring to Figure 1 and Figure 2, the inventor found through research that when performing three-dimensional display, there is a voltage difference between the first electrode 21 and the second electrode 22, and the longitudinal electric field formed by the first electrode 21 and the second electrode 22 can drive the rotation of liquid crystal molecules. There are at least two first electrodes 21 with different voltages, so as to form longitudinal electric fields with different intensities arranged along the first direction X. The longitudinal electric fields with different intensities make the liquid crystal molecules rotate by different angles, thereby forming a refractive index gradient and forming a plurality of grating units 40 arranged along the first direction X. Therefore, the grating units 40 can also include liquid crystal molecules. However, a transverse electric field is formed between the first electrodes 21 with different voltages. The existence of the transverse electric field will cause the electro-flexural effect of the liquid crystal molecules, changing the rotation behavior of the liquid crystal molecules. The liquid crystal molecules in the liquid crystal grating cannot be flipped according to the ideal situation, and the liquid crystal molecules rotate in the direction opposite to the pre-tilt angle, resulting in the problem of reverse domains.

[0048] Figure 3 The top view structural schematic diagram of a liquid crystal grating provided by an embodiment of the present invention Figure 3 The second electrode 22 and the second substrate 12 are omitted in the illustration. Figure 4 Along Figure 3 The cross-sectional structural schematic diagram in the AA' direction in, refer to Figure 3 And Figure 4 , the grating unit 40 includes a plurality of first electrodes 21 and a plurality of second electrodes 22. The plurality of first electrodes 21 are located between the first substrate 11 and the liquid crystal layer 30, and the plurality of first electrodes 21 are arranged at intervals along the first direction X. The plurality of second electrodes 22 are located between the second substrate 12 and the liquid crystal layer 30, and the plurality of second electrodes 22 are arranged at intervals along the first direction X. Along the first direction X, there is a certain distance between two adjacent second electrodes 22. There are at least two first electrodes 21 with different voltages, and there are at least two second electrodes 22 with different voltages.

[0049] In the liquid crystal grating provided by the embodiment of the present invention, there are at least two first electrodes 21 with different voltages, and a transverse electric field is generated between the first electrodes 21. There are at least two second electrodes 22 with different voltages, and a transverse electric field is generated between the second electrodes 22. Thus, the transverse electric field is dispersed between the first electrode 21 and the second electrode 22, and the transverse electric field is dispersed between the first substrate 11 and the second substrate 12, rather than concentrated on one substrate (the substrate includes the first substrate 11 and the second substrate 12), thereby reducing the transverse electric field intensity of a single substrate. Reducing the adverse effect of the transverse electric field on the rotation of liquid crystal molecules and improving the reverse domain problem.

[0050] Exemplarily, refer to Figure 3 And Figure 4, when performing stereoscopic display, there is a voltage difference between the first electrode 21 and the second electrode 22. The longitudinal electric field formed by the first electrode 21 and the second electrode 22 can drive the rotation of liquid crystal molecules to form a plurality of grating units 40, and the plurality of grating units 40 are arranged repeatedly along the first direction X. The liquid crystal grating is used for light diffraction deflection. When stereoscopic display is not performed, the grating units 40 are not formed, and the liquid crystal grating is not used for light diffraction deflection. Among them, the direction of the longitudinal electric field can be the third direction Z or the reverse direction of the third direction Z.

[0051] Exemplarily, referring to Figure 3 and Figure 4 , in the same grating unit 40, there are at least two first electrodes 21 with different voltages and at least two second electrodes 22 with different voltages. In the same grating unit 40, the transverse electric field is dispersed between the first substrate 11 and the second substrate 12 to reduce the adverse effect of the transverse electric field on the rotation of liquid crystal molecules and improve the reverse domain problem.

[0052] Optionally, referring to Figure 4 , in the same grating unit 40, the grating unit 40 includes a plurality of electrode groups 50 arranged along the first direction X. The electrode group 50 includes at least one first electrode 21 and at least one second electrode 22. In the same electrode group 50, the first electrode 21 and one second electrode 22 at least partially overlap, the first electrode 21 and one second electrode 22 overlap, or a part of the first electrode 21 and one second electrode 22 overlaps. The voltage difference between the first electrode 21 and the second electrode 22 is the first voltage difference. The longitudinal electric field formed by the first voltage difference can drive the rotation of liquid crystal molecules. Among them, the first voltage difference is the difference between the voltage of the first electrode 21 and the voltage of the second electrode 22, that is, the first voltage difference is the voltage of the first electrode 21 minus the voltage of the second electrode 22.

[0053] Exemplarily, referring to Figure 4 , an electrode group 50 includes one first electrode 21 and one second electrode 22. There is a first voltage difference between the voltages of the first electrode 21 and the second electrode 22 in the same electrode group 50. In other embodiments, an electrode group 50 includes a plurality of first electrodes 21 and one second electrode 22.

[0054] Figure 5 is a schematic diagram of an electric field formed by a first voltage difference provided by an embodiment of the present invention. Referring to Figure 5 , each first voltage difference has the same polarity. The longitudinal electric field formed by the first electrode 21 and the second electrode 22 ( Figure 5 the arrows in indicate the longitudinal electric field) has the same electric field direction. The longitudinal electric field formed by the first electrode 21 and the second electrode 22 drives the liquid crystal molecules to rotate in the same direction.

[0055] Exemplarily, referring toFigure 5 , the plurality of first electrodes 21 include a first sub-first electrode 211, a second sub-first electrode 212, a third sub-first electrode 213, and a fourth sub-first electrode 214. The plurality of second electrodes 22 include a first sub-second electrode 221, a second sub-second electrode 222, a third sub-second electrode 223, and a fourth sub-second electrode 224. The voltage of the first sub-first electrode 211 is greater than the voltage of the first sub-second electrode 221, and the first sub-first electrode 211 and the first sub-second electrode 221 form a first voltage difference with a positive polarity. The voltage of the second sub-first electrode 212 is greater than the voltage of the second sub-second electrode 222, and the second sub-first electrode 212 and the second sub-second electrode 222 form a first voltage difference with a positive polarity. The voltage of the third sub-first electrode 213 is greater than the voltage of the third sub-second electrode 223, and the third sub-first electrode 213 and the third sub-second electrode 223 form a first voltage difference with a positive polarity. The voltage of the fourth sub-first electrode 214 is greater than the voltage of the fourth sub-second electrode 224, and the fourth sub-first electrode 214 and the fourth sub-second electrode 224 form a first voltage difference with a positive polarity. Figure 5 The arrows in it indicate the longitudinal electric field, and the thickness of the arrows represents the magnitude of the longitudinal electric field. The thicker the arrow, the greater the longitudinal electric field and the greater the first voltage difference.

[0056] Figure 6 is a schematic diagram of a first voltage difference provided by an embodiment of the present invention. Refer to Figure 5 and Figure 6 , in the same grating unit 40, along the first direction, each first voltage difference gradually increases, the intensity of the longitudinal electric field formed by each electrode group 50 gradually increases, and the rotation angle of the liquid crystal molecules gradually increases. In other embodiments, in the same grating unit 40, along the first direction, the first voltage difference gradually decreases. It can be understood that since in the same grating unit 40, along the first direction, the first voltage difference gradually increases or gradually decreases, the first voltage difference between two adjacent grating units 40 jumps. Correspondingly, the refractive index formed by the liquid crystal molecules gradually changes in the same grating unit 40 and jumps at the boundary between two adjacent grating units 40, thus forming a grating with a diffraction function.

[0057] Optionally, refer to Figures 4 - 6, the grating unit 40 includes M electrode groups 50, where M is a positive integer greater than 1. In the same grating unit 40, along the first direction X, the first voltage differences corresponding to the first electrode group 50 to the Mth electrode group 50 change linearly. In the same grating unit 40, the intensities of the longitudinal electric fields formed by the respective electrode groups 50 increase linearly or decrease linearly. Since the rotation angle of the liquid crystal molecules is proportional to the intensity of the longitudinal electric field, the linearly changing first voltage differences cause the liquid crystal molecules to form a linearly changing refractive index, simplifying the optical path. In other embodiments, the first voltage differences corresponding to the first electrode group 50 to the Mth electrode group 50 follow other variation rules.

[0058] Exemplarily, referring to Figures 4 - 6 , taking M = 4 as an example. The first voltage difference formed by the first sub-first electrode 211 and the first sub-second electrode 221 is denoted as V31, the first voltage difference formed by the second sub-first electrode 212 and the second sub-second electrode 222 is denoted as V32, the first voltage difference formed by the third sub-first electrode 213 and the third sub-second electrode 223 is denoted as V33, and the first voltage difference formed by the fourth sub-first electrode 214 and the fourth sub-second electrode 224 is denoted as V34. V31, V32, V33, and V34 increase linearly. In other embodiments, the grating unit 40 includes other numbers of electrode groups 50.

[0059] Figure 7 Another schematic diagram of the first voltage difference provided by the embodiments of the present invention, referring to Figure 7 , in the same grating unit 40, along the first direction, the first voltage differences corresponding to the respective electrode groups 50 first increase and then decrease. In the same grating unit 40, along the first direction X, the first voltage differences corresponding to the respective electrode groups 50 change in a broken line.

[0060] Figure 8 Another schematic diagram of the first voltage difference provided by the embodiments of the present invention, referring to Figure 8 , in the same grating unit 40, along the first direction, the first voltage differences corresponding to the respective electrode groups 50 gradually increase. In the same grating unit 40, along the first direction X, the first voltage differences corresponding to the respective electrode groups 50 change in a curve.

[0061] Figure 9 A schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiments of the present invention, referring to Figures 4 - 6 , and Figure 9 , in the same grating unit 40, along the first direction X, the voltages of the respective first electrodes 21 gradually increase, and the voltages of the respective second electrodes 22 gradually decrease. In the same grating unit 40, the first voltage differences corresponding to the respective electrode groups 50 gradually increase.

[0062] In other embodiments, in the same grating unit 40, along the first direction X, the voltages of the respective first electrodes 1 gradually decrease, and the voltages of the respective second electrodes 22 gradually increase. In the same grating unit 40, the first voltage differences corresponding to the respective electrode groups 50 gradually decrease.

[0063] Optionally, referring to Figure 4 and Figure 9 , the grating unit includes M first electrodes 21 and N second electrodes 22, and both M and N are positive integers greater than 1. Along the first direction X, the voltages of the first first electrode 21 to the Mth first electrode 21 change linearly, that is, the voltages of the first first electrode 21 to the last first electrode 21 change linearly. The voltages of the first second electrode 22 to the Nth second electrode 22 change linearly. That is, the voltages of the first second electrode 22 to the last second electrode 22 change linearly.

[0064] Exemplarily, referring to Figure 4 and Figure 9 , an electrode group 50 includes a first electrode 21 and a second electrode 22. M = N = 4. In the same grating unit 40, along the first direction X, the voltages of the first first electrode 21 to the fourth first electrode 21 change linearly, and the voltages of the first second electrode 22 to the fourth second electrode 22 change linearly. In other embodiments, the voltages of the first first electrode 21 to the last first electrode 21 change according to other rules, and / or the voltages of the first second electrode 22 to the last second electrode 22 change according to other rules.

[0065] Figure 10 Another voltage distribution diagram of the first electrode and the second electrode provided by the embodiment of the present invention. In the same grating unit 40, along the first direction, the voltages of the first first electrode 21 to the last first electrode 21 gradually increase, and the voltages of the respective first electrodes 21 change in a curve. In the same grating unit 40, along the first direction, the voltages of the first second electrode 22 to the last second electrode 22 gradually decrease, and the voltages of the respective second electrodes 22 change in a curve.

[0066] Optionally, referring to Figure 4 , the number of the first electrodes 21 is the same as that of the second electrodes 22. Along the direction perpendicular to the plane of the first substrate 11, the first electrodes 21 and the second electrodes 22 are in one-to-one correspondence, the first electrodes 21 and the second electrodes 22 in one-to-one correspondence overlap, and the first electrodes 21 and the second electrodes 22 in one-to-one correspondence are located in the same electrode group 50.

[0067] Exemplarily, referring to Figure 4, along the direction perpendicular to the plane where the first substrate 11 is located, the corresponding first electrodes 21 and the second electrodes 22 are directly opposite and coincide with each other. The corresponding first electrodes 21 and the second electrodes 22 occupy the same area along the direction perpendicular to the plane where the first substrate 11 is located.

[0068] Optionally, referring to Figure 4 and Figure 9 , for the corresponding first electrodes 21 and the second electrodes 22, the voltage values of the first electrodes 21 and the second electrodes 22 are the same but the polarities are opposite. Thereby, the lateral electric field is evenly dispersed between the first electrodes 21 and the second electrodes 22, and the lateral electric field is dispersed between the first substrate 11 and the second substrate 12. The lateral electric field between the first electrodes 21 on the first substrate 11 is the same as the lateral electric field between the second electrodes 22 on the second substrate 12, thereby minimizing the lateral electric field intensity of a single substrate.

[0069] Exemplarily, referring to Figure 1 and Figure 2 , the voltage of the first sub-first electrode 211 is +1V, the voltage of the second sub-first electrode 212 is +2V, the voltage of the third sub-first electrode 213 is +3V, and the voltage of the fourth sub-first electrode 214 is +4V. The voltage of the second electrode 22 is 0V. The voltage difference formed between the first sub-first electrode 211 and the second electrode 22 is 1V, the voltage difference formed between the second sub-first electrode 212 and the second electrode 22 is 2V, the voltage difference formed between the third sub-first electrode 213 and the second electrode 22 is 3V, and the voltage difference formed between the fourth sub-first electrode 214 and the second electrode 22 is 4V. The voltage difference formed between the fourth sub-first electrode 214 and the first sub-first electrode 211 in the adjacent grating unit 40 is 3V. The lateral electric field formed between the first electrodes 21 is relatively large, resulting in the liquid crystal molecules being unable to flip as ideally, and the liquid crystal molecules rotate in the direction opposite to the pretilt angle, resulting in the problem of reverse domains.

[0070] Exemplarily, referring to Figures 4 - 6 , and Figure 9, the voltage of the first sub-first electrode 211 is +0.5V, the voltage of the second sub-first electrode 212 is +1V, the voltage of the third sub-first electrode 213 is +1.5V, and the voltage of the fourth sub-first electrode 214 is +2V. The voltage of the first sub-second electrode 221 is -0.5V, the voltage of the second sub-second electrode 222 is -1V, the voltage of the third sub-second electrode 223 is -1.5V, and the voltage of the fourth sub-second electrode 224 is -2V. The voltage difference formed by the first sub-first electrode 211 and the first sub-second electrode 221 is 1V, the voltage difference formed by the second sub-first electrode 212 and the second sub-second electrode 222 is 2V, the voltage difference formed by the third sub-first electrode 213 and the third sub-second electrode 223 is 3V, and the voltage difference formed by the fourth sub-first electrode 214 and the fourth sub-second electrode 224 is 4V. The voltage difference formed by the fourth sub-first electrode 214 and the first sub-first electrode 211 in the adjacent grating unit 40 is 1.5V. The voltage difference formed by the fourth sub-second electrode 224 and the first sub-second electrode 221 in the adjacent grating unit 40 is 1.5V. The lateral electric field formed between the first electrodes 21 is reduced, the adverse effect of the lateral electric field on the rotation of liquid crystal molecules is reduced, and the reverse domain problem is improved.

[0071] Figure 11 Another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention, refer to Figure 4 and Figure 11 , in the same grating unit 40, along the first direction X, the voltage of the first first electrode 21 to the last first electrode 21 increases linearly, and the voltage of the first second electrode 22 to the last second electrode 22 decreases linearly. The absolute value of the voltage change rate of each first electrode 21 is greater than the absolute value of the voltage change rate of each second electrode 22. In other embodiments, in the same grating unit 40, the absolute value of the voltage change rate of each first electrode 21 is less than the absolute value of the voltage change rate of each second electrode 22.

[0072] Figure 12 Another schematic cross-sectional structure diagram of the liquid crystal grating provided by the embodiment of the present invention, Figure 13 Another schematic diagram of the voltage distribution of the first electrode provided by the embodiment of the present invention, refer to Figure 12 and Figure 13 , the grating unit 40 includes M first electrodes 21, and M is a positive integer greater than 1. Along the first direction X, the voltage of the first first electrode 1 to the Pth first electrode 21 changes linearly according to the first change rate K1, and the voltage of the (P + 1)th first electrode 21 to the Mth first electrode 21 changes linearly according to the second change rate K2, where 1 < P < M. The absolute value of the first change rate K1 is not equal to the absolute value of the second change rate K2. In the same grating unit 40, along the first direction X, the voltage of each first electrode 21 changes in a broken line.

[0073] Exemplarily, referring to Figure 12 , an electrode group 50 includes a first electrode 21 and a second electrode 22. The first electrode 21 includes a first sub-first electrode 211, a second sub-first electrode 212,..., a P-th sub-first electrode 21P, a (P + 1)-th sub-first electrode 21P1,..., an M-th sub-first electrode 21M arranged in sequence. Among them, in the same grating unit 40, the first sub-first electrode 211 is the first first electrode 21, the second sub-first electrode 212 is the second first electrode 21, the P-th sub-first electrode 21P is the P-th first electrode 21, the (P + 1)-th sub-first electrode 21P1 is the (P + 1)-th first electrode 21, and the M-th sub-first electrode 21M is the M-th first electrode 21. The voltages of the first sub-first electrode 211 to the P-th sub-first electrode 21P change linearly according to a first change rate K1. The voltages of the (P + 1)-th sub-first electrode 21P1 to the M-th sub-first electrode 21M change linearly according to a second change rate K2.

[0074] Figure 14 Another schematic diagram of the second electrode voltage distribution provided by the embodiment of the present invention, referring to Figure 12 and Figure 14 , the grating unit 40 includes N second electrodes 22, where N is a positive integer greater than 1. Along the first direction X, the voltages of the first second electrode 22 to the Q-th second electrode 22 change linearly according to a third change rate K3, and the voltages of the (Q + 1)-th second electrode 22 to the N-th second electrode 22 change linearly according to a fourth change rate K4, where 1 < Q < N. The absolute value of the third change rate K3 is not equal to the absolute value of the fourth change rate K4. In the same grating unit 40, along the first direction X, the voltages of the respective second electrodes 22 change in a stepped manner.

[0075] Exemplarily, referring to Figure 12 , an electrode group 50 includes a first electrode 21 and a second electrode 22. The second electrode 22 includes a first sub-second electrode 221, a second sub-second electrode 222,..., a Q-th sub-second electrode 22Q, a (Q + 1)-th sub-second electrode 22Q1,..., an N-th sub-second electrode 22N arranged in sequence. Among them, in the same grating unit 40, the first sub-second electrode 221 is the first second electrode 22, the second sub-second electrode 222 is the second second electrode 22, the Q-th sub-second electrode 22Q is the Q-th second electrode 22, the (Q + 1)-th sub-second electrode 22Q1 is the (Q + 1)-th second electrode 22, and the N-th sub-second electrode 22N is the N-th second electrode 22. The voltages of the first sub-second electrode 221 to the Q-th sub-second electrode 22Q change linearly according to a third change rate K3. The voltages of the (Q + 1)-th sub-second electrode 22Q1 to the N-th sub-second electrode 22N change linearly according to a fourth change rate K4.

[0076] Figure 15 Another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention, refer to Figures 12 - 15 , and Figure 6 , M = N, P = Q. An electrode group 50 includes a first electrode 21 and a second electrode 22. The number of the first electrodes 21 is equal to the number of the second electrodes 22. Both the second change rate K2 and the third change rate K3 are 0, and the absolute value of the first change rate K1 is equal to the absolute value of the fourth change rate K4. The first change rate K1 is a positive number, and the fourth change rate K4 is a negative number. The difference between the first change rate K1 and the third change rate K3 is equal to the difference between the second change rate K2 and the fourth change rate K4. Thus, along the first direction X, the first voltage differences corresponding to the respective electrode groups 50 change linearly.

[0077] Figure 16 Another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention, Figure 17 Another schematic diagram of the first voltage difference provided by the embodiment of the present invention, refer to Figure 12 , Figure 16 and Figure 17 , M = N, P = Q. Both the second change rate K2 and the third change rate K3 are 0, and the absolute value of the first change rate K1 is less than the absolute value of the fourth change rate K4. The difference between the first change rate K1 and the third change rate K3 is less than the difference between the second change rate K2 and the fourth change rate K4. Thus, along the first direction X, the first voltage differences corresponding to the first electrode group 50 to the Pth electrode group 50 change linearly, and the first voltage differences corresponding to the (P + 1)th electrode group 50 to the Mth electrode group 50 change linearly. The first voltage differences corresponding to the first electrode group 50 to the Mth electrode group 50 change in a broken line. The change rate of the first voltage differences corresponding to the (P + 1)th electrode group 50 to the Mth electrode group 50 is greater than the change rate of the first voltage differences corresponding to the first electrode group 50 to the Pth electrode group 50.

[0078] Figure 18 Another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention, Figure 19 Another schematic diagram of the first voltage difference provided by the embodiment of the present invention, refer to Figure 18 and Figure 19 , M is equal to N, P is not equal to Q. Both the second change rate K2 and the third change rate K3 are 0, and the absolute value of the first change rate K1 is equal to the absolute value of the fourth change rate K4. The first voltage differences corresponding to the first electrode group 50 to the Mth electrode group 50 change in a broken line. The broken line formed by the first voltage differences corresponding to the first electrode group 50 to the Mth electrode group 50 includes 3 line segments.

[0079] Figure 20Another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention, Figure 21 Another schematic diagram of the first voltage difference provided by the embodiment of the present invention, refer to Figure 12 , Figure 20 and Figure 21 , the grating unit 40 includes M electrode groups 50. Along the first direction X, the voltages of the first first electrode 1 to the Pth first electrode 21 change linearly at the first change rate K1, and the voltages of the (P + 1)th first electrode 21 to the Mth first electrode 21 change linearly at the second change rate K2, where 1 < P < M. The first change rate K1 is a positive number, and the second change rate K2 is 0. Along the first direction X, the voltages of the first second electrode 22 to the Nth second electrode 22 change linearly at the third change rate K3, and the third change rate K3 is a negative number. The first voltage differences corresponding to the first electrode group 50 to the Pth electrode group 50 change linearly. The first voltage differences corresponding to the (P + 1)th electrode group 50 to the Mth electrode group 50 change linearly. The first voltage differences corresponding to the first electrode group 50 to the Mth electrode group 50 change in a broken line, and the broken line formed by the first voltage differences corresponding to the first electrode group 50 to the Mth electrode group 50 includes 2 line segments.

[0080] Figure 22 Another schematic cross-sectional structure diagram of the liquid crystal grating provided by the embodiment of the present invention, refer to Figure 22 , along the direction perpendicular to the plane where the first substrate 11 is located, a plurality of first electrodes 21 overlap with the same second electrode 22. One first electrode 21 and a part of the second electrodes 22 are located in the same electrode group 50. A plurality of electrode groups 50 share the same second electrode 22. In other embodiments, along the direction perpendicular to the plane where the first substrate 11 is located, a plurality of second electrodes 22 overlap with the same first electrode 21.

[0081] Exemplarily, refer to Figure 22 , along the direction perpendicular to the plane where the first substrate 11 is located, the first sub-first electrode 211 and the second sub-first electrode 212 both overlap with the first sub-second electrode 221, and the third sub-first electrode 213 and the fourth sub-first electrode 214 both overlap with the second sub-second electrode 222.

[0082] Optionally, refer to Figure 4 , along the first direction X, each first electrode 1 has the same width, that is, any two first electrodes 21 have the same width. Along the first direction X, each second electrode 22 has the same width, that is, any two second electrodes 22 have the same width.

[0083] Exemplarily, refer to Figure 4 , along the first direction X, the first electrode 21 and the second electrode 22 have the same width.

[0084] Figure 23 Another cross-sectional structure schematic diagram of a liquid crystal grating provided by an embodiment of the present invention. Refer to Figure 23 , along the first direction X, each first electrode 1 has the same width, each second electrode 22 has the same width, and the first electrode 21 and the second electrode 22 have different widths. The width of the first electrode 21 is greater than the width of the second electrode 22. In other embodiments, the width of the first electrode 21 is less than the width of the second electrode 22.

[0085] Figure 24 Another cross-sectional structure schematic diagram of a liquid crystal grating provided by an embodiment of the present invention. In the same electrode group 50, the first electrode 21 and the second electrode 22 are staggered along the first direction X. In the same electrode group 50, the direction of the electric field formed between the first electrode 21 and the second electrode 22 intersects the third direction Z.

[0086] Optionally, refer to Figure 4 , along the first direction X, each first electrode 21 is arranged at equal intervals, each first electrode 21 is evenly arranged, and the distance between two adjacent first electrodes 21 is a fixed value. Each second electrode is arranged at equal intervals, each second electrode is evenly arranged, and the distance between two adjacent second electrodes 22 is a fixed value.

[0087] Optionally, refer to Figure 3 and Figure 4 , both the first electrode 21 and the second electrode 22 are strip-shaped electrodes extending along the second direction Y, and the first direction X intersects the second direction Y. A plurality of first electrodes 21 extend along the second direction Y and are arranged along the first direction X, and a plurality of second electrodes 22 extend along the second direction Y and are arranged along the first direction X.

[0088] Optionally, refer to Figure 4 , in the same grating unit 40, the voltage differences between at least some adjacent first electrodes 21 are the same, and / or the voltage differences between at least some adjacent second electrodes 22 are the same.

[0089] Exemplarily, refer to Figure 4, the voltage of the first sub-first electrode 211 is +0.5V, the voltage of the second sub-first electrode 212 is +1V, the voltage of the third sub-first electrode 213 is +1.5V, and the voltage of the fourth sub-first electrode 214 is +2V. The voltage difference between the second sub-first electrode 212 and the first sub-first electrode 211 is 0.5V, the voltage difference between the third sub-first electrode 213 and the second sub-first electrode 212 is 0.5V, and the voltage difference between the fourth sub-first electrode 214 and the third sub-first electrode 213 is 0.5V. The voltage differences between adjacent first electrodes 21 are the same. The voltage of the first sub-second electrode 221 is -0.5V, the voltage of the second sub-second electrode 222 is -1V, the voltage of the third sub-second electrode 223 is -1.5V, and the voltage of the fourth sub-second electrode 224 is -2V. The voltage difference between the second sub-second electrode 222 and the first sub-second electrode 221 is -0.5V, the voltage difference between the third sub-second electrode 223 and the second sub-second electrode 222 is -0.5V, and the voltage difference between the fourth sub-second electrode 224 and the third sub-second electrode 223 is -0.5V. The voltage differences between adjacent second electrodes 22 are the same.

[0090] Optionally, referring to Figure 4 and Figure 9 , in each grating unit 40, the first electrodes 21 with the same ordinal number have the same voltage, and the second electrodes 22 with the same ordinal number have the same voltage. The voltage distribution rules of the multiple first electrodes 21 in each grating unit 40 are the same, and the voltage distribution rules of the multiple second electrodes 22 in each grating unit 40 are the same. Thus, the first electrodes 21 with the same voltage in multiple grating units 40 can be connected to the same power supply terminal, and the second electrodes 22 with the same voltage in multiple grating units 40 can be connected to the same power supply terminal, reducing the number of power supply terminals. Herein, the ordinal number of the first electrode 21 or the second electrode 22 in the grating unit 40 refers to which first electrode 21 or second electrode 22 in the grating unit 40 it is. Herein, the voltage distribution rule of the first electrode 21 or the second electrode 22 refers to the distribution rule presented by the voltages of the multiple first electrodes 21 or the multiple second electrodes 22 along the first direction X.

[0091] Exemplarily, referring to Figure 4 and Figure 9, the grating unit 40 includes a first sub-grating unit 41 and a second sub-grating unit 42. Both the first sub-grating unit 41 and the second sub-grating unit 42 include 4 electrode groups 50. An electrode group 50 includes a first electrode 21 and a second electrode 22. In the grating unit 40, the 4 first electrodes 21 are arranged in sequence, and the 4 second electrodes 22 are arranged in sequence. The first first electrode 21 in the first sub-grating unit 41 has the same voltage as the first first electrode 21 in the second sub-grating unit 42, and the second first electrode 21 in the first sub-grating unit 41 has the same voltage as the second first electrode 21 in the second sub-grating unit 42. The first second electrode 22 in the first sub-grating unit 41 has the same voltage as the first second electrode 22 in the second sub-grating unit 42, and the second second electrode 22 in the first sub-grating unit 41 has the same voltage as the second second electrode 22 in the second sub-grating unit 42.

[0092] Figure 25 is another schematic diagram of the voltage distribution of the first electrode and the second electrode provided by the embodiment of the present invention. Refer to Figure 4 and Figure 25 , a plurality of grating units 40 include at least one first sub-grating unit 41 and a second sub-grating unit 42. The first sub-grating unit 41 is adjacent to the second sub-grating unit 42. The first electrodes 21 with the same ordinal number in the first sub-grating unit 41 and the second sub-grating unit 42 have different voltages, and / or the second electrodes 22 with the same ordinal number in the first sub-grating unit 41 and the second sub-grating unit 42 have different voltages. The voltage distribution rules of the plurality of first electrodes 21 in the first sub-grating unit 41 are different from the voltage distribution rules of the plurality of first electrodes 21 in the second sub-grating unit 42, and / or the voltage distribution rules of the plurality of second electrodes 22 in the first sub-grating unit 41 are different from the voltage distribution rules of the plurality of second electrodes 22 in the second sub-grating unit 42.

[0093] Exemplarily, refer to Figure 4 and Figure 25, in the first sub-grating unit 41, the voltages of a part of the first electrodes 21 with smaller ordinals change linearly at a first change rate K1, and the voltages of a part of the first electrodes 21 with larger ordinals change linearly at a second change rate K2. The voltages of a part of the second electrodes 22 with smaller ordinals change linearly at a third change rate K3, and the voltages of a part of the second electrodes 22 with larger ordinals change linearly at a fourth change rate K4. In the second sub-grating unit 42, the voltages of a part of the first electrodes 21 with smaller ordinals change linearly at a fifth change rate K5, and the voltages of a part of the first electrodes 21 with larger ordinals change linearly at a sixth change rate K6. The voltages of a part of the second electrodes 22 with smaller ordinals change linearly at a seventh change rate K7, and the voltages of a part of the second electrodes 22 with larger ordinals change linearly at an eighth change rate K8. The first change rate K1 is not equal to the fifth change rate K5, the second change rate K2 is not equal to the sixth change rate K6, and the voltage distribution rules of the multiple first electrodes 21 in the first sub-grating unit 41 are different from those of the multiple first electrodes 21 in the second sub-grating unit 42. The third change rate K3 is not equal to the seventh change rate K7, the fourth change rate K4 is not equal to the eighth change rate K8, and the voltage distribution rules of the respective second electrodes 22 in the first sub-grating unit 41 are different from those of the respective second electrodes 22 in the second sub-grating unit 42.

[0094] Exemplarily, referring to Figure 4 and Figure 25 , the first change rate K1 is equal to the sixth change rate K6, and the second change rate K2 is equal to the fifth change rate K5. The third change rate K3 is equal to the eighth change rate K8, and the fourth change rate K4 is equal to the seventh change rate K7. The first voltage differences corresponding to the respective electrode groups 50 in the first sub-grating unit 41 increase linearly, the first voltage differences corresponding to the respective electrode groups 50 in the second sub-grating unit 42 increase linearly, and the change rate of each first voltage difference in the first sub-grating unit 41 is equal to the change rate of each first voltage difference in the second sub-grating unit 42. Along the first direction X, the first sub-grating unit 41 and the second sub-grating unit 42 have the same first voltage difference distribution, the first sub-grating unit 41 and the second sub-grating unit 42 have the same longitudinal electric field distribution, the first sub-grating unit 41 and the second sub-grating unit 42 have the same liquid crystal rotation angle distribution, the first sub-grating unit 41 and the second sub-grating unit 42 have the same refractive index gradient, and the first sub-grating unit 41 and the second sub-grating unit 42 have the same optical diffraction performance.

[0095] Optionally, referring to Figure 4 and Figure 9, along the first direction X, there is a second voltage difference between the two first electrodes 21 that are respectively located in two adjacent grating units 40 and are the closest to each other, and there is a third voltage difference between the two second electrodes 22 that are respectively located in two adjacent grating units 40 and are the closest to each other. Among them, both the second voltage difference and the third voltage difference are not zero. A transverse electric field is generated between the first electrodes 21 that have the second voltage difference and are respectively located in two adjacent grating units 40. A transverse electric field is generated between the second electrodes 22 that have the third voltage difference and are respectively located in two adjacent grating units 40. In the embodiment of the present invention, the transverse electric field is dispersed on the first substrate 11 and the second substrate 12 instead of being concentrated on one substrate, thereby reducing the intensity of the transverse electric field of a single substrate.

[0096] Exemplarily, referring to Figure 4 and Figure 9 , along the first direction X, the voltage distribution rules of the multiple first electrodes 21 in the first sub-grating unit 41 are the same as those of the multiple first electrodes 21 in the second sub-grating unit 42, and the voltage distribution rules of the respective second electrodes 22 in the first sub-grating unit 41 are the same as those of the respective second electrodes 22 in the second sub-grating unit 42. Among them, the voltage distribution rule is the spatial distribution rule of the voltages of the respective first electrodes 21 or the respective second electrodes 22 in the grating unit 40. In the first sub-grating unit 41 and the second sub-grating unit 42, along the first direction X, the voltage of the first electrode 21 increases linearly, the voltage of the first electrode 21 in the first sub-grating unit 41 and the second sub-grating unit 42 has a jump, and the second voltage difference is the maximum value of the voltage differences between adjacent first electrodes 21. In the first sub-grating unit 41 and the second sub-grating unit 42, along the first direction X, the voltage of the second electrode 22 decreases linearly, the voltage of the second electrode 22 in the first sub-grating unit 41 and the second sub-grating unit 42 has a jump, and the third voltage difference is the maximum value of the voltage differences between adjacent second electrodes 22. Therefore, the second voltage difference and the third voltage difference are dispersed on the first substrate 11 and the second substrate 12, reducing the value of the voltage difference of a single substrate, thereby reducing the intensity of the transverse electric field of a single substrate.

[0097] Figure 26 is a schematic cross-sectional structure diagram of another liquid crystal grating in the inventor's research process, Figure 27 is a schematic diagram of the voltage distribution of the first electrode and the second electrode of another liquid crystal grating in the inventor's research process. Referring to Figure 26 and Figure 27, the inventor found through research that along the first direction X, between two adjacent grating units 40, a first electric field TE1 is formed between the two first electrodes 21 that are closest to each other. The first electric field TE1 is a transverse electric field. The liquid crystal grating includes a first alignment layer 31, and the first alignment layer 31 is located between the first electrode 21 and the liquid crystal layer 30. The alignment direction of the first alignment layer 31 is opposite to the electric field direction of the first electric field TE1. Under the combined influence of the first electric field TE1 and the longitudinal electric field, the liquid crystal molecules at the position of the S1 region rotate along the Figure 1 arrow direction in Figure 1 and produce a reverse flip, generating bubble-like reverse domains in the S1 region. Among them, the liquid crystal molecules at the position of the S1 region are close to the first electrode 21. That is to say, in addition to the influence of the intensity of the transverse electric field, the inventor found during the research process that the alignment direction of the first alignment layer 31 is opposite to the electric field direction of the first electric field TE1, which easily leads to the problem of reverse domains.

[0098] Figure 28 FIG. [X] is a schematic cross-sectional structure diagram of another liquid crystal grating provided by an embodiment of the present invention. Figure 29 FIG. [Y] is a schematic diagram of the voltage distribution of the first electrode and the second electrode of another liquid crystal grating provided by an embodiment of the present invention. Refer to Figure 28 and Figure 29 , the liquid crystal grating includes at least one liquid crystal cell 100. The liquid crystal cell 100 includes a first substrate 11, a first electrode 21, a first alignment layer 31, a liquid crystal layer 30, and a second substrate 12 arranged in sequence. In the first state ST1, the liquid crystal cell 100 includes a plurality of first grating units 401 arranged along the first direction X. The first grating unit 401 includes a plurality of first electrodes 21 spaced apart from each other along the first direction X. Along the first direction X, there is a certain distance between two adjacent first electrodes 21. Along the first direction X, a first electric field TE1 is formed between the two first electrodes 21 that are closest to each other and are respectively located in two adjacent first grating units 401. In the liquid crystal cell 100, the alignment direction of the first alignment layer 31 is the same as the electric field direction of the first electric field TE1. The electric field direction received by the liquid crystal molecules adjacent to the first alignment layer 31 is towards the alignment direction of the first alignment layer 31, and will not be towards the opposite direction of the alignment of the first alignment layer 31. The liquid crystal molecules adjacent to the first alignment layer 31 will not produce a reverse flip, reducing the adverse effect of the transverse electric field on the rotation of the liquid crystal molecules and improving the problem of reverse domains.

[0099] Note: The specific figures [X] and [Y] need to be filled in according to the actual figures in the original text. Also, the tags Figure 1 , , etc. are preserved as they are without further translation as they seem to be some kind of reference identifiers in the context of the patent text.The liquid crystal cell 100 further includes a second alignment layer 32. The second alignment layer 32 is located between the second electrode 22 and the liquid crystal layer 30. In the first state ST1, the first grating unit 401 includes a plurality of second electrodes 22 spaced apart from each other along the first direction X. Along the first direction X, there is a certain distance between two adjacent second electrodes 22. Along the first direction X, the second electric field TE2 is formed between the two second electrodes 22 that are respectively located in two adjacent first grating units 401 and are the closest to each other. The second electric field TE2 is a transverse electric field. In the liquid crystal cell 100, the alignment direction of the second alignment layer 32 is the same as the electric field direction of the second electric field TE2. The electric field direction received by the liquid crystal molecules adjacent to the second alignment layer 32 is towards the alignment direction of the second alignment layer 32, and will not be towards the reverse alignment direction of the second alignment layer 32. The liquid crystal molecules adjacent to the second alignment layer will not produce reverse flipping, reducing the adverse effects of the transverse electric field on the rotation of liquid crystal molecules and improving the reverse domain problem.

[0100] Figure 30 Another schematic three-dimensional structure diagram of a liquid crystal grating provided by an embodiment of the present invention Figure 31 Another schematic working process diagram of a liquid crystal grating provided by an embodiment of the present invention, refer to Figure 28 、 Figure 30 and Figure 31 As shown in FIGS.

[0101] Figure 32 Another schematic working process diagram of a liquid crystal grating provided by an embodiment of the present invention, refer to Figure 28 、 Figure 30 and Figure 32, in the second state ST2, in the second liquid crystal cell 102, the second alignment direction R21 is the same as the electric field direction of the third electric field TE3, and the liquid crystal molecules adjacent to the first alignment layer 31 will not undergo reverse flipping. In the second state ST2, in the second liquid crystal cell 102, the fourth alignment direction R22 is the same as the electric field direction of the seventh electric field TE7, and the liquid crystal molecules adjacent to the second alignment layer 32 will not undergo reverse flipping. The second alignment direction R21 is opposite to the fourth alignment direction R22. Among them, in the second liquid crystal cell 102, in the second state ST2, along the first direction X, the seventh electric field TE7 is formed between the two second electrodes 22 that are respectively located in two adjacent grating units 40 and are the closest to each other. The seventh electric field TE7 is a transverse electric field. In the second state ST2, in the second liquid crystal cell 102, the first electrode 21 and the second electrode 22 form a second longitudinal electric field VE2, and the direction of the second longitudinal electric field VE2 is the third direction Z, pointing from the first electrode 21 to the second electrode 22.

[0102] Figure 33 Schematic diagram of the working timing of a liquid crystal grating provided by an embodiment of the present invention, refer to Figures 28 - 33 , the liquid crystal grating includes two stacked liquid crystal cells 100. The working time of the liquid crystal grating includes multiple frames F. In the same frame F, one of the two liquid crystal cells 100 is mainly used for light diffraction deflection, and the other is not used or is used to assist in light deflection. The deflection angle of the light is mainly determined by one of the two liquid crystal cells 100.

[0103] Exemplarily, refer to Figure 33 , one frame F is the time period when a color light irradiates one eye of the observer. For a color display scheme using RGB three primary colors, when performing stereoscopic display, a complete picture requires six frames. These six frames are the left-eye green frame LG, the left-eye blue frame LB, the left-eye red frame LR, the right-eye green frame RG, the right-eye blue frame RB, and the right-eye red frame RR. Figure 33 The dashed box in

[0104] Optionally, refer to Figures 28 - 33, the two liquid crystal cells 100 are a first liquid crystal cell 101 and a second liquid crystal cell 102 respectively. The multiple frames F include a first frame F1 and a second frame F2, and the second frame F2 is after the first frame F1. In the first frame F1, the first liquid crystal cell 101 operates in a first state ST1, and the first liquid crystal cell 101 is configured to mainly diffract and deflect light toward the first side of the optical axis of the liquid crystal grating. In the second frame F2, the second liquid crystal cell 102 operates in a second state ST2, and the second liquid crystal cell 102 is configured to mainly diffract and deflect light toward the second side of the optical axis of the liquid crystal grating, and the first side and the second side are located on opposite sides of the optical axis of the liquid crystal grating. Wherein, the optical axis of the liquid crystal grating is perpendicular to the plane where the first substrate 11 is located.

[0105] Exemplarily, referring to Figure 31 and Figure 33 , in the first frame F1, the first liquid crystal cell 101 operates in a first state ST1, and the first liquid crystal cell 101 is configured to mainly diffract and deflect light toward the first side of the optical axis of the liquid crystal grating. The first side of the optical axis of the liquid crystal grating is the right side of the optical axis of the liquid crystal grating. For an observer facing the light propagation direction, the green light (schematically shown by green light, but not limited thereto) is deflected into the observer's left eye.

[0106] Exemplarily, referring to Figure 32 and Figure 33 , in the second frame F2, the second liquid crystal cell 102 operates in a second state ST2, and the second liquid crystal cell 102 is configured to mainly diffract and deflect light toward the second side of the optical axis of the liquid crystal grating. The second side of the optical axis of the liquid crystal grating is the left side of the optical axis of the liquid crystal grating. For an observer facing the light propagation direction, the green light (schematically shown by green light, but not limited thereto) is deflected into the observer's right eye.

[0107] Figure 34 Schematic diagram of a stereoscopic display device provided by an embodiment of the present invention, referring to Figure 34 , the stereoscopic display device includes a light source 61, a spatial light modulator 62, and a grating assembly 64 arranged in sequence. The grating assembly 64 includes at least one liquid crystal grating in the above embodiment.

[0108] Exemplarily, referring to Figure 34 , the light source 61 is used to sequentially emit coherent red, green, and blue backlights. The spatial light modulator 62 includes a first spatial light modulator 621 for phase modulation and a second spatial light modulator 622 for amplitude modulation. The stereoscopic display device further includes a field lens 63, and the field lens 63 is located between the spatial light modulator 62 and the grating assembly 64. The field lens 63 is at least used to improve the ability of the marginal light emitted by the spatial light modulator 62 to enter the grating assembly 64. The grating assembly 64 is used to form a left-eye image and a right-eye image based on the incident light.

[0109] Exemplarily, referring to Figure 34 , the grating assembly 64 includes three liquid crystal gratings, namely a first liquid crystal grating 641, a second liquid crystal grating 642, and a third liquid crystal grating 643. The extending directions of the first electrodes 21 of any two of the first liquid crystal grating 641, the second liquid crystal grating 642, and the third liquid crystal grating 643 may be different. In other embodiments, the grating assembly 64 may further include other numbers of liquid crystal gratings.

[0110] Note that the above is only a preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein. Various obvious changes, re-adjustments, combinations with each other, and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments may be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A liquid crystal grating, characterized in that, It includes a first substrate, a second substrate and a liquid crystal layer, and the liquid crystal layer is located between the first substrate and the second substrate; A plurality of grating units, arranged along a first direction, including a plurality of first electrodes and a plurality of second electrodes; a plurality of the first electrodes are located between the first substrate and the liquid crystal layer and are arranged at intervals from each other along the first direction; a plurality of the second electrodes are located between the second substrate and the liquid crystal layer and are arranged at intervals from each other along the first direction; There are at least two of the first electrodes having different voltages, and there are at least two of the second electrodes having different voltages; In the same grating unit, along the first direction, the voltages of the respective first electrodes gradually increase, and the voltages of the respective second electrodes gradually decrease; or, In the same grating unit, along the first direction, the voltages of the respective first electrodes gradually decrease, and the voltages of the respective second electrodes gradually increase.

2. The liquid crystal grating according to claim 1, wherein In the same grating unit, it includes a plurality of electrode groups arranged along the first direction, and the electrode group includes at least one first electrode and at least one second electrode; in the same electrode group, the first electrode and a second electrode at least partially overlap, and the voltage difference between the two is a first voltage difference.

3. The liquid crystal grating according to claim 2, wherein Each of the first voltage differences has the same polarity.

4. The liquid crystal grating according to claim 2, wherein In the same grating unit, along the first direction, the first voltage difference gradually increases or gradually decreases.

5. The liquid crystal grating according to claim 4, wherein, The grating unit includes M of the electrode groups, and M is a positive integer greater than 1; In the same grating unit, along the first direction, the first voltage differences corresponding to the first electrode group to the Mth electrode group change linearly.

6. The liquid crystal grating according to claim 1, characterized in that, The grating unit includes M of the first electrodes and N of the second electrodes, and both M and N are positive integers greater than 1; Along the first direction, the voltages of the first first electrode to the Mth first electrode change linearly, and the voltages of the first second electrode to the Nth second electrode change linearly.

7. The liquid crystal grating according to claim 1 or 4, characterized in that The grating unit includes M of the first electrodes, and M is a positive integer greater than 1; Along the first direction, the voltage of the first first electrode to the Pth first electrode changes linearly according to a first change rate, and the voltage of the (P + 1)th first electrode to the Mth first electrode changes linearly according to a second change rate, where 1 < P < M; The absolute value of the first change rate is not equal to the absolute value of the second change rate.

8. The liquid crystal grating according to claim 7, wherein The grating unit includes N of the second electrodes, and N is a positive integer greater than 1; Along the first direction, the voltage of the first second electrode to the Qth second electrode changes linearly according to a third change rate, and the voltage of the (Q + 1)th second electrode to the Nth second electrode changes linearly according to a fourth change rate, where 1 < Q < N; The absolute value of the third change rate is not equal to the absolute value of the fourth change rate.

9. The liquid crystal grating according to claim 1, wherein, The number of the first electrodes is the same as the number of the second electrodes; Along the direction perpendicular to the plane where the first substrate is located, the first electrodes and the second electrodes correspond to each other one by one.

10. The liquid crystal grating according to claim 9, characterized in that, For the first electrodes and the second electrodes corresponding to each other one by one, the voltage of the first electrode and the voltage of the second electrode have the same numerical value and opposite polarities.

11. The liquid crystal grating according to claim 1, wherein In a direction perpendicular to the plane of the first substrate, a plurality of the first electrodes overlap with the same second electrode, or a plurality of the second electrodes overlap with the same first electrode.

12. The liquid crystal grating according to claim 1, wherein In the first direction, each of the first electrodes has the same width, and each of the second electrodes has the same width.

13. The liquid crystal grating according to claim 1, wherein In the first direction, the first electrodes are arranged at equal intervals, and the second electrodes are arranged at equal intervals.

14. The liquid crystal grating according to claim 1, wherein, Both the first electrode and the second electrode are strip electrodes extending in the second direction, and the first direction intersects the second direction.

15. The liquid crystal grating according to claim 1, characterized in that, In the same grating unit, the voltage differences between at least some adjacent first electrodes are the same; and / or, the voltage differences between at least some adjacent second electrodes are the same.

16. The liquid crystal grating according to claim 1, wherein In each of the grating units, the first electrodes with the same ordinal number have the same voltage, and the second electrodes with the same ordinal number have the same voltage.

17. The liquid crystal grating according to claim 1, characterized in that The plurality of grating units include at least one first sub-grating unit and a second sub-grating unit. The first sub-grating unit is adjacent to the second sub-grating unit. The first electrodes with the same ordinal number in the first sub-grating unit and the second sub-grating unit have different voltages, and / or, the second electrodes with the same ordinal number in the first sub-grating unit and the second sub-grating unit have different voltages.

18. The liquid crystal grating according to claim 1, wherein, In the first direction, there is a second voltage difference between the two first electrodes that are respectively located in two adjacent grating units and are the closest to each other, and there is a third voltage difference between the two second electrodes that are respectively located in two adjacent grating units and are the closest to each other.

19. A stereoscopic display device, characterized in that, It includes a light source, a spatial light modulator, and a grating assembly arranged in sequence; The grating assembly includes at least one liquid crystal grating according to any one of claims 1-18.

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