Liquid crystal grating and driving method thereof, and three-dimensional display device

Abstract

Embodiments of the present invention disclose a liquid crystal grating, a driving method thereof, and a three-dimensional display device. The liquid crystal grating is used to modulate incident light and output deflected outgoing light; the incident light includes at least a first incident light and a second incident light, the first incident light being modulated by the liquid crystal grating to output a first outgoing light, and the second incident light being modulated by the liquid crystal grating to output a second outgoing light, and the optical band of the first incident light and the optical band of the second incident light at least partially do not overlap; when the liquid crystal grating modulates the first incident light and the second incident light, at least one of the minimum value of the corresponding modulation voltage and the modulation duration is different. The embodiments of the present invention optimize the high-frequency modulation performance of the liquid crystal grating and enhance the display effect by setting at least one of the minimum value of the corresponding modulation voltage and the modulation duration to be different when the liquid crystal grating modulates different incident light.

Description

Technical Field

[0001] The embodiments of the present invention relate to display technology, and in particular to a liquid crystal grating and a driving method thereof, and a three-dimensional display device. Background Art

[0002] With the development of display technology, various display devices continue to emerge. In order to meet people's demand for stereoscopic display of display devices, three-dimensional display has become an important development direction in the current display field.

[0003] Existing naked-eye 3D display devices typically use a liquid crystal grating to modulate the direction of light transmission, creating left-eye and right-eye images for the human eye. Because a single frame of 3D display requires two modulations to create the left and right-eye images, and color display requires modulation of red, green, and blue light, the operating frequency of the liquid crystal grating is very high. Existing liquid crystal gratings suffer from insufficient response, which affects the display quality. Summary of the Invention

[0004] Embodiments of the present invention provide a liquid crystal grating, a driving method thereof, and a three-dimensional display device. The liquid crystal grating can be used in a three-dimensional display device. By setting at least one of the minimum modulation voltage and the modulation duration corresponding to different incident light rays to be different, the high-frequency modulation performance of the liquid crystal grating is optimized, thereby improving the display effect.

[0005] In a first aspect, an embodiment of the present invention provides a liquid crystal grating for modulating incident light and outputting deflected outgoing light;

[0006] The incident light comprises at least a first incident light and a second incident light, the first incident light being modulated by the liquid crystal grating to output a first outgoing light, the second incident light being modulated by the liquid crystal grating to output a second outgoing light, and the wavelength band of the first incident light and the wavelength band of the second incident light at least partially not overlapping;

[0007] When the liquid crystal grating modulates the first incident light and the second incident light, at least one of a minimum value of a corresponding modulation voltage and a modulation duration is different.

[0008] In a second aspect, an embodiment of the present invention further provides a method for driving a liquid crystal grating, applicable to the above-mentioned liquid crystal grating, wherein the liquid crystal grating includes a plurality of grating groups, each of the grating groups includes a plurality of driving electrodes, wherein odd-numbered driving electrodes in the same grating group are connected to a first signal terminal, even-numbered driving electrodes are connected to a second signal terminal, and each driving electrode is connected to a corresponding driving voltage terminal;

[0009] Modulating the incident light includes a first stage of writing a corresponding modulation voltage to the driving electrode, the first stage including a pre-charging stage and a gradient voltage writing stage;

[0010] The driving method includes:

[0011] In the pre-charging stage, the first signal terminal applies a first pre-charging voltage to the corresponding driving electrode, and the second signal terminal applies a second pre-charging voltage to the corresponding driving electrode;

[0012] In the gradient voltage writing stage, the driving voltage end applies a gradient voltage to the corresponding driving electrode;

[0013] The first pre-charge voltage is the same as the second pre-charge voltage and is the same as the minimum voltage value of the gradient voltage.

[0014] In a third aspect, an embodiment of the present invention further provides a three-dimensional display device, comprising a backlight module, a spatial light modulator, and the above-mentioned liquid crystal grating stacked in sequence;

[0015] The backlight module is used to provide field sequential collimated coherent backlight required for three-dimensional display;

[0016] The spatial light modulator is used to modulate the phase and amplitude of the field sequential collimated coherent backlight;

[0017] The liquid crystal grating is used to modulate the light beam output by the spatial light modulator into a first direction light beam and a second direction light beam and output the modulated light beams.

[0018] A liquid crystal grating provided in an embodiment of the present invention is configured to modulate incident light and output deflected outgoing light. The incident light includes at least a first incident light and a second incident light. The first incident light is modulated by the liquid crystal grating to output a first outgoing light, and the second incident light is modulated by the liquid crystal grating to output a second outgoing light. The wavelengths of the first incident light and the second incident light at least partially do not overlap. When the liquid crystal grating modulates the first and second incident light, at least one of the minimum value of the corresponding modulation voltage and the modulation duration differs. By setting the minimum value of the corresponding modulation voltage and the modulation duration to differ when the liquid crystal grating modulates the first and second incident light, the high-frequency modulation performance of the liquid crystal grating is optimized, thereby enhancing display effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic structural diagram of a three-dimensional display device provided by an embodiment of the present invention;

[0020] Figure 2 for Figure 1 Schematic diagram of the driving principle of the three-dimensional display device shown;

[0021] Figure 3 A schematic structural diagram of a liquid crystal grating provided by an embodiment of the present invention;

[0022] Figure 4 A timing diagram illustrating the definition of the modulation duration of the liquid crystal grating provided in an embodiment of the present invention;

[0023] Figure 5 A schematic diagram of the driving principle of a three-dimensional display device provided by an embodiment of the present invention;

[0024] Figure 6 A schematic diagram of the driving principle of another three-dimensional display device provided by an embodiment of the present invention;

[0025] Figure 7 A schematic diagram of a driving timing of a liquid crystal grating provided by an embodiment of the present invention;

[0026] Figure 8 A schematic diagram of the driving principle of another three-dimensional display device provided by an embodiment of the present invention;

[0027] Figure 9 A schematic diagram of a driving timing of a liquid crystal grating provided by an embodiment of the present invention;

[0028] Figure 10 A schematic diagram of the driving principle of another three-dimensional display device provided by an embodiment of the present invention;

[0029] Figure 11 A schematic diagram of the driving principle of another three-dimensional display device provided by an embodiment of the present invention;

[0030] Figure 12 A schematic diagram of a gradient voltage interval applied to a driving electrode according to an embodiment of the present invention;

[0031] Figure 13 A schematic diagram of another gradient voltage interval applied to a driving electrode according to an embodiment of the present invention;

[0032] Figure 14 A schematic diagram of the circuit principle of a grating group provided by an embodiment of the present invention;

[0033] Figure 15 A schematic diagram of the principle of applying voltage to a liquid crystal grating provided by an embodiment of the present invention;

[0034] Figure 16 A timing diagram of a liquid crystal grating when voltage is applied thereto provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0036] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present invention are described based on the angles shown in the accompanying drawings and should not be understood as limitations on the embodiments of the present invention. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is formed "on" or "under" another element, it can not only be formed directly "on" or "under" another element, but can also be indirectly formed "on" or "under" another element through an intermediate element. The terms "first", "second", etc. are only used for descriptive purposes and do not indicate any order, quantity or importance, but are only used to distinguish different components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0037] Figure 1 A schematic diagram of the structure of a three-dimensional display device provided by an embodiment of the present invention, referring to Figure 1 The three-dimensional display device 1 may include a backlight module 10, a spatial light modulator 11, a focusing lens 12, and a liquid crystal grating 13 stacked in sequence. The backlight module 10 is used to provide a field-sequential collimated coherent light beam required for three-dimensional display. The backlight module 10 may be provided with a light source and a beam expansion and collimation component ( Figure 1(The specific structure of the backlight module 10 is not shown in the figure). For example, for color display, the light source can provide field-sequential coherent red R light, green G light and blue B light. The beam expander and collimator component expands and collimates the light emitted by the light source and then transmits it to the spatial light modulator 11. The spatial light modulator 11 is arranged on the side of the backlight module 10 close to the human eye 14, and is used to modulate the phase and amplitude of the field-sequential collimated coherent light beam. Specifically, the spatial light modulator 11 may include a phase spatial light modulator 111 and an amplitude spatial light modulator 112. The phase spatial light modulator 111 is used to adjust the phase of the field-sequential collimated coherent light beam, and the amplitude spatial light modulator 112 is used to adjust the amplitude of the field-sequential collimated coherent light beam. The phase spatial light modulator 111 and the amplitude spatial light modulator 112 can both be liquid crystal panel structures, and their detailed structures are not described in detail here. The converging field lens 12 may include at least one lens for converging the modulated field-sequential collimated coherent light beam to the liquid crystal grating 13, thereby improving the ability of the edge rays of the modulated field-sequential collimated coherent light beam emitted by the spatial light modulator 11 to be incident on the liquid crystal grating 13. The liquid crystal grating 13 is used to adjust the transmission direction of the light beam and transmit the left-eye image and the right-eye image in the three-dimensional optical image to the human eye 14 respectively, so that the human eye 14 can observe the three-dimensional stereoscopic image. The liquid crystal grating 13 can be provided with multiple liquid crystal modules with different alignment directions. Figure 1 Three liquid crystal modules are exemplarily shown, which are a first liquid crystal grating 131, a second liquid crystal grating 132, and a third liquid crystal grating 133 along the direction of light transmission. The grating orientations of the first liquid crystal grating 131, the second liquid crystal grating 132, and the third liquid crystal grating 133 can be 0 degrees, 45 degrees, and 45 degrees, respectively (the grating orientations of the second liquid crystal grating 132 and the third liquid crystal grating 133 are perpendicular). The above is only one optional arrangement of the liquid crystal grating 13. In specific implementation, the liquid crystal grating 13 can be arranged according to actual needs.

[0038] Figure 2 for Figure 1 The driving principle diagram of the three-dimensional display device shown in FIG. 1 is a schematic diagram of the driving principle of the three-dimensional display device shown in FIG. 1 , wherein, for simplicity, Figure 2Only one spatial light modulator (SLM) and one liquid crystal grating (LCG) driving timing are shown. In the actual driving process, different SLMs or different LCGs are loaded with different driving signals, but the timing of the loaded signals is the same. Therefore, only one SLM and one LCG are shown in the driving principle diagram. It is understandable that since the left eye and right eye images need to be displayed separately during three-dimensional display, if the human eye wants to observe a 60Hz display image, the frequency of the left eye image and the right eye image needs to reach 60Hz, so the driving frequency of the SLM needs to reach 120Hz; for color display, the R, G, and B color lights need to be modulated separately. Since the wavelengths of the three light rays are different, the LCG does not contain a pixel design. To achieve the same deflection effect, the LCG needs to be modulated separately for different light rays, so the modulation frequency of the LCG needs to reach 360Hz.

[0039] Figure 2 The timing diagram of two frames is shown as an example. These two frames can be understood as the first frame being the left eye picture, represented by F1 (L), and the second frame being the right eye picture, represented by F2 (R). After the scanning is completed, the human eye can observe a complete three-dimensional picture. It should be noted that the SLM selected in this embodiment is a liquid crystal spatial light modulator. The structure of the SLM is similar to that of the liquid crystal display panel. The difference is that the pixel arrangement of the SLM is different from that of the ordinary liquid crystal display panel. Generally, the pixel arrangement in the ordinary liquid crystal display panel is that the red, green and blue sub-pixels are arranged alternately in the row direction, and the sub-pixels in the column direction have the same color. In the SLM, there is only one color sub-pixel in a row, for example, the red sub-pixels are 1, 4, 7... rows, the green sub-pixels are 2, 5, 8... rows, and the blue sub-pixels are 3, 6, 9... rows. In three-dimensional display, the backlights of R, G, and B colors are modulated in sequence. Figure 2 The first and second rows in the figure represent the timing of SLM and LCG, respectively. The R, G, and B in the first row refer to the row-by-row scanning and loading of driving voltages on the pixel electrodes corresponding to the red R sub-pixel, green B sub-pixel, and blue B sub-pixel in the SLM, respectively. The R, G, and B in the second row refer to the time periods when the LCG modulates the R, G, and B three-color light, respectively. Since there is no pixel structure in the LCG, it is necessary to modulate each light to be transmitted. Therefore, for the RGB three-color light, the modulation frequency of the LCG is three times that of the SLM, that is, a group of R, G, and B in the first row represents three time periods in a frame when modulating the SLM, and a group of G, B, and R in the second row represents three sub-frames in a frame when modulating the LCG.

[0040] Since LCG needs to work at a high frequency (the LCG driving frequency is 360Hz when the human eye sees 60Hz), and LCG is a liquid crystal device, due to reasons such as the high viscosity of the liquid crystal, there is a problem in the existing technology that the display effect is affected by insufficient liquid crystal response.

[0041] To address the aforementioned issues, embodiments of the present invention provide a liquid crystal grating for use in a three-dimensional display device. The liquid crystal grating is configured to modulate incident light and then output deflected outgoing light. The incident light includes at least a first incident light and a second incident light. The first incident light is modulated by the liquid crystal grating to output a first outgoing light, and the second incident light is modulated by the liquid crystal grating to output a second outgoing light. The wavelength band of the first incident light and the wavelength band of the second incident light at least partially do not overlap. When the liquid crystal grating modulates the first and second incident light, at least one of the minimum value of the corresponding modulation voltage and the modulation duration is different. By setting at least one of the minimum value of the modulation voltage and the modulation duration to be different when the liquid crystal grating modulates different incident light, the high-frequency modulation performance of the liquid crystal grating is optimized, thereby enhancing the display effect.

[0042] The above is the core idea of the embodiment of the present invention. The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0043] Figure 3 A schematic diagram of the structure of a liquid crystal grating provided by an embodiment of the present invention, referring to Figure 3 The liquid crystal grating includes a first substrate 100, a second substrate 200, and a liquid crystal layer 300 located between the first substrate 100 and the second substrate 200. A first electrode 110 (common electrode) is provided on one side of the first substrate 100, and a plurality of second electrodes 120 are provided on one side of the second substrate 200. When different modulation voltages are applied between the first electrode 110 and the second electrode 120, the liquid crystal molecules can be rotated to different directions to modulate light. Specifically, the plurality of second electrodes 120 form an electrode group. Each electrode group, the first electrode 110 in the corresponding area, and the liquid crystal layer between the electrode group and the first electrode 110 constitute a grating group (a period of the grating) in the liquid crystal grating. The entire liquid crystal grating structure is provided with multiple electrode groups. When the liquid crystal grating is driven, the electrodes in each electrode group are applied with corresponding gradient voltages, and the liquid crystal molecules in the liquid crystal layer 300 are arranged periodically, forming a liquid crystal grating that modulates light. Exemplarily, the incident light includes at least a first incident light a and a second incident light b, such as a red light and a green light. The first incident light a is modulated by the liquid crystal grating to output a first outgoing light a1, and the second incident light b is modulated by the liquid crystal grating to output a second outgoing light b1. Figure 3The schematic diagram shows that the liquid crystal grating is in the same state, and the first outgoing light a1 and the second outgoing light b1 have different propagation directions. In other embodiments, the liquid crystal can be in different states when modulating the first incident light and the second incident light, so that the two output light beams have the same propagation direction. In specific implementations, different electrode groups can include the same number of second electrodes 120 or different numbers of second electrodes 120, which is not limited in this embodiment of the present invention.

[0044] It is understandable that when the liquid crystal grating is operating, it is necessary to control the modulation voltage to drive the phase of the liquid crystal molecules to change in the range of 0 to 2π. The inventors have found that when modulating light of different wavelengths, the voltage required for the liquid crystal phase to change by 2π is different. In addition, when modulating light, it is only necessary for the phase of the liquid crystal molecules to change by 2π (when the liquid crystal grating is operating, the effect of the phase of the liquid crystal molecules in the range of 0 to 2π or π to 3π is equivalent). The greater the driving voltage, the faster the liquid crystal responds. By setting the liquid crystal grating to modulate incident light of different wavelengths, the corresponding minimum value of the modulation voltage is different, which is conducive to improving the response speed of the liquid crystal, thereby optimizing the high-frequency modulation performance of the liquid crystal grating. On the other hand, the liquid crystal response speed is different when the liquid crystal grating modulates different incident light. Therefore, different modulation durations can be set, or the modulation voltage and modulation duration can be changed simultaneously. The specific implementation can be designed according to actual conditions.

[0045] Optionally, the modulation period of the liquid crystal grating includes multiple subframes, and the modulation duration of an incident light corresponds to the duration of a subframe, wherein the end time of the Nth subframe is the same as the start time of the N+1th subframe, and N is an integer ≥2.

[0046] The modulation period of the liquid crystal grating is the display period of one display image. For example, for a three-dimensional display device including RGB three-color light, one modulation period includes modulating the left-eye image and the right-eye image of the three-color RGB light. Figure 2 One modulation cycle is shown in FIG.

[0047] For example, taking the liquid crystal grating modulating two incident light rays as an example, Figure 4 A timing diagram of the modulation duration of the liquid crystal grating provided in an embodiment of the present invention, referring to Figure 4 The liquid crystal grating modulates the first incident light a and the second incident light b alternately multiple times, and the first modulation is the first incident light a; the modulation start time corresponding to the nth modulation of the first incident light a is t 11 The end time of the modulation of the second incident light b for the n-1th time is t 21 , t 11 =t 21 ; The modulation end time corresponding to the first incident light a of the nth modulation is t 12, the modulation start time of the second incident light ray b for the nth time is t 22 , t 12 = t 22 ; the modulation end time of the second incident light ray b for the nth time is t 23 , the modulation start time of the first incident light ray a for the (n + 1)th time is t 13 , t 23 = t 13 ; where n is an integer greater than 1.

[0048] It can be understood that if there are more than two types of incident light rays to be modulated, for example, modulating RGB three light rays in sequence, then the end time of modulating the R light ray is the same as the start time of the next modulation of the G light ray, the end time of modulating the G light ray is the same as the start time of the next modulation of the B light ray, and the end time of modulating the B light ray is the same as the start time of the next modulation of the R light ray.

[0049] Optionally, the first incident light ray and the second incident light ray satisfy: λ1 > λ2;

[0050] The modulation duration satisfies: t1 > t2;

[0051] Where, λ1 represents the central wavelength of the first incident light ray, λ2 represents the central wavelength of the second incident light ray, t1 represents the modulation duration of modulating the first incident light ray, and t2 represents the modulation duration of modulating the second incident light ray.

[0052] It can be understood that when λ1 > λ2, for common liquid crystal materials, satisfying Δn(λ1) represents the refractive index difference of the birefringence of the liquid crystal in the liquid crystal grating for the first incident light ray, Δn(λ2) represents the refractive index difference of the birefringence of the liquid crystal in the liquid crystal grating for the second incident light ray. In the same liquid crystal state, the phase corresponding to the modulation of the first incident light ray by the liquid crystal grating is less than the phase of the second incident light ray. In other words, if the first incident light ray and the second incident light ray are to reach the same phase, a larger angle of deflection of the liquid crystal is required when modulating the first incident light ray. Therefore, the response speed of the liquid crystal when modulating the first incident light ray is less than the response speed of the liquid crystal when modulating the second incident light ray. In this embodiment, t1 > t2 is set, t1 = t 12 - t 11 , t2 = t 23 - t 22 , that is, more modulation time is reserved when modulating the first incident light ray to optimize the modulation process of the liquid crystal grating.

[0053] It should be noted that in another embodiment, if the liquid crystal material satisfies then t1 < t2 needs to be set, and the principle is similar to the previous embodiment and will not be elaborated here. In this embodiment, it is assumed that the liquid crystal material satisfies For example.

[0054] Optionally, the incident light includes a first incident light, a second incident light, and a third incident light, and the first incident light, the second incident light, and the third incident light satisfy: λ1>λ2>λ3;

[0055] The modulation duration satisfies: t1>t2, t1>t3;

[0056] Wherein, λ1 represents the central wavelength of the first incident light, λ2 represents the central wavelength of the second incident light, λ3 represents the central wavelength of the third incident light, t1 represents the modulation time of modulating the first incident light, t2 represents the modulation time of modulating the second incident light, and t3 represents the modulation time of modulating the third incident light.

[0057] The first incident light can be R light, the second incident light can be G light, and the third incident light can be B light. For example, the center wavelengths of commonly used RGB lights are 638nm, 532nn, and 442nm, respectively. Since liquid crystal gratings can be used in three-dimensional display devices, Figure 5 A schematic diagram of the driving principle of a three-dimensional display device provided by an embodiment of the present invention, referring to Figure 5 In this embodiment, the modulation duration satisfies: t1>t2, t1>t3.

[0058] It is understandable that since the liquid crystal responds the slowest to the modulation of the R light, t1 is increased in this embodiment, that is, more time is allocated to the R subframe in the entire frame so that the liquid crystal has enough time. Among them, the time when the backlight is turned on can be adaptively adjusted according to the timing of the LCG. Since the time of each subframe of the SLM is relatively long, it can be set to the same length, that is, the same as the prior art, to simplify the driving timing of the three-dimensional display device. In specific implementation, since the modulation period of the liquid crystal grating is determined when the modulation frequency of the liquid crystal grating is constant, the length of the R subframe can be changed by adjusting the length of the G subframe and / or the B subframe. In specific implementation, refer to Figure 5 , you can set t2 = t3. In addition, it should be noted that Figure 5The third row, R-on, G-on, and B-on, refer to the R, G, and B light rays emitted by the backlight module (BL), respectively. Taking into account the response time required for liquid crystal, R-on is later than the scanning of the R light ray in the SLM (the first R-on in the figure corresponds to the scanning of the first R light ray in the SLM scanning sequence, the second G-on corresponds to the scanning of the first G light ray, and the second B-on corresponds to the scanning of the first B light ray, that is, the backlight is turned on later than the scanning time of the corresponding color sub-pixel of the SLM, and the first G-on corresponds to the G not shown in the previous frame). In addition, the SLM includes a pixel design, and the R light will not pass through the G and B sub-pixels. Therefore, there can be a time difference between the backlight lighting time and the SLM scanning time.

[0059] In specific implementation, there can be multiple combinations of adjusting the length of the G subframe and / or B subframe. Based on the same duration of the R, G, and B subframes, only the length of the B subframe can be shortened, only the length of the G subframe can be shortened, the length of the G subframe and the B subframe can be shortened at the same time, or the length of the G subframe can be increased while shortening the length of the B subframe. The specific implementation can be designed according to actual conditions.

[0060] When λ1>λ2>λ3, we have Δn(λ1) represents the refractive index difference of the liquid crystal in the liquid crystal grating to the first incident light, Δn(λ2) represents the refractive index difference of the liquid crystal in the liquid crystal grating to the second incident light, and Δn(λ3) represents the refractive index difference of the liquid crystal in the liquid crystal grating to the third incident light. The response time of the liquid crystal becomes shorter in sequence. Figure 6 A schematic diagram of the driving principle of another three-dimensional display device provided by an embodiment of the present invention, referring to Figure 6 , optionally, t1>t2>t3. This setting is conducive to maximally optimizing the modulation process of the liquid crystal grating, wherein the specific duration of each subframe can be designed according to the actual liquid crystal material and the corresponding wavelength, and is not specifically limited in the embodiment of the present invention.

[0061] Optionally, the modulation of the incident light includes a first stage and a second stage. In the first stage, the driving electrode of the liquid crystal grating is written with a corresponding modulation voltage. The first stage and the second stage satisfy:

[0062]

[0063] Among them, t 1a Indicates the duration of the first stage when modulating the first incident light, t 1b Indicates the duration of the second stage when modulating the first incident light, t 1b =t1-t 1a , t 2a Indicates the duration of the first stage when modulating the second incident light, t 2bIndicates the duration of the second stage when modulating the second incident light, t 2b =t2-t 2a .

[0064] The modulation of the incident light includes a first stage and a second stage. In the first stage, the driving electrode of the liquid crystal grating is written with a corresponding modulation voltage. In the second stage, the liquid crystal in the liquid crystal grating responds to the modulation voltage and deflects. After deflection, it stabilizes for a period of time. The backlight is turned on during the stable state. For example, Figure 7 A driving timing diagram of a liquid crystal grating provided by an embodiment of the present invention, referring to Figure 7 , taking the incident light including the first incident light a and the second incident light b as an example, when modulating the first incident light a, the first stage is t 1a , the second stage is t 1b , when modulating the second incident light b, the first stage is t 2a , the second stage is t 2b When λ1>λ2, the response time required for the first incident light is long, so setting It is helpful to reserve enough response time when modulating the first incident light. Figure 7 , optional, t 1a =t 2a , that is, the first stage of the design for modulating the first incident light and the second incident light is the same, only t is increased 1b , which is conducive to simplifying the driving method.

[0065] Optionally, the modulation of the incident light includes a first stage and a second stage. In the first stage, the driving electrode of the liquid crystal grating is written with a corresponding modulation voltage. The first stage and the second stage satisfy:

[0066]

[0067] Among them, t 1a Indicates the duration of the first stage when modulating the first incident light, t 1b Indicates the duration of the second stage when modulating the first incident light, t 1b =t1-t 1a , t 2a Indicates the duration of the first stage when modulating the second incident light, t 2b Indicates the duration of the second stage when modulating the second incident light, t 3a Indicates the duration of the first stage when modulating the third incident light, t 2b =t2-t 2a , t 3b Indicates the duration of the second stage when modulating the third incident light, t 3b =t3-t 3a .

[0068] and Figure 7 Similar to the embodiment, Figure 8 A schematic diagram of the driving principle of another three-dimensional display device provided by an embodiment of the present invention, referring to Figure 8 The first incident light, the second incident light and the third incident light are R, G and B light respectively. The R subframe includes the first stage t 1a and the second stage t 1b , G subframe includes the first phase t 2a and the second stage t 2b , B subframe includes t 3a and the second stage t 3b , by setting This is helpful to reserve enough response time when modulating each color of light. Figure 8 , optional, t 1a =t 2a =t 3a The specific implementation can be designed according to actual conditions.

[0069] In another embodiment, the duration of the first stage and the second stage may be adjusted simultaneously. Optionally, the modulation of the incident light includes the first stage and the second stage. In the first stage, the corresponding modulation voltage is written to the driving electrode of the liquid crystal grating. The first stage satisfies:

[0070] t 1a >t 2a ;

[0071] The second stage meets:

[0072] t 1b >t 2b ;

[0073] Among them, t 1a Indicates the duration of the first stage when modulating the first incident light, t 1b Indicates the duration of the second stage when modulating the first incident light, t 1b =t1-t 1a , t 2a Indicates the duration of the first stage when modulating the second incident light, t 2b Indicates the duration of the second stage when modulating the second incident light, t 2b =t2-t 2a .

[0074] For example, Figure 9 A driving timing diagram of a liquid crystal grating provided by an embodiment of the present invention, referring to Figure 9 In this embodiment, by setting t 1a >t 2aWhen λ1>λ2, the driving voltage range when modulating the first incident light is often larger than the driving voltage range when modulating the second incident light. The liquid crystal grating includes multiple electrode groups. The greater the loading voltage, the stronger the coupling effect between the electrodes. Therefore, setting t 1a >t 2a , when modulating the first incident light, the driving voltage can be written more times to weaken the coupling effect. By setting t 1b >t 2b , which is beneficial to reserve sufficient response time when modulating the first incident light.

[0075] Optionally, the modulation of the incident light includes a first stage and a second stage. In the first stage, a corresponding modulation voltage is written to the grating electrode of the liquid crystal grating. The first stage satisfies:

[0076] t 1a >t 2a ≥t 3a ;

[0077] The second stage meets:

[0078] t 1b >t 2b ≥t 3b ;

[0079] Among them, t 1a Indicates the duration of the first stage when modulating the first incident light, t 1b Indicates the duration of the second stage when modulating the first incident light, t 1b =t1-t 1a , t 2a Indicates the duration of the first stage when modulating the second incident light, t 2b Indicates the duration of the second stage when modulating the second incident light, t 2b =t2-t 2a , t 3a Indicates the duration of the first stage when modulating the third incident light, t 3b Indicates the duration of the second stage when modulating the third incident light, t 3b =t3-t 3a .

[0080] and Figure 9 Similar to the embodiment, Figure 10 A schematic diagram of the driving principle of another three-dimensional display device provided by an embodiment of the present invention, referring to Figure 10 The first incident light, the second incident light and the third incident light are R, G and B light respectively. The R subframe includes the first stage t 1a and the second stage t 1b , G subframe includes the first phase t 2a and the second stage t2b , B subframe includes t 3a and the second stage t 3b , this embodiment sets t 1a >t 2a ≥t 3a , t 1b >t 2b ≥t 3b , and at the same time optimize the design of the time of the first and second stages to achieve better driving effect.

[0081] Figure 11 A schematic diagram of the driving principle of another three-dimensional display device provided by an embodiment of the present invention, referring to Figure 11 , the second phase t in the R subframe 1b Including the first sub-stage t 11b and the second sub-phase t 12b , the second stage t in G subframe 2b Including the first sub-stage t 21b and the second sub-phase t 22b , the second stage t in the B subframe 3b Including the first sub-stage t 31b and the second sub-phase t 32b , where the first sub-stage t 11b , the first sub-stage t 21b and the first sub-stage t 31b They are the response time of liquid crystal deflection after the driving voltage is loaded when modulating R, G, and B light, respectively. In the second sub-stage, t 12b , the second sub-stage t 22b and the second sub-phase t 32b Corresponding to the lighting time of R, G, and B backlight respectively. It should be noted that the second stage includes two time periods: liquid crystal deflection and liquid crystal state stabilization. When the backlight is turned on, the liquid crystal is in a stable state. In this embodiment, the duration of backlight on (i.e., the length of R-on, G-on, and B-on) is set to be the same, and the moment of backlight off is the same as the starting moment when LCG modulates the next wavelength (for example, the end moment of G-on is the same as the starting moment of t3, which is also the latest end moment of the backlight). In other words, in this embodiment, t 11b , t 21b and t 31b The length of the corresponding liquid crystal deflection period is different, and t 12b =t 22b =t 32b In other embodiments, different backlight on-times may be set to be different, for example, the backlight off-time may be a certain time earlier than that of the present embodiment. Specific implementation may be designed based on actual conditions.

[0082] Based on the above embodiment, optionally, the liquid crystal grating includes a plurality of grating groups, each grating group includes a plurality of driving electrodes, and when the liquid crystal grating modulates the incident light, a gradient voltage is applied to the plurality of driving electrodes in the same grating group;

[0083] The voltage applied to the driving electrode satisfies:

[0084] V 1min <V 2min ;

[0085] Where V 1min Indicates the minimum voltage applied to the driving electrode when modulating the first incident light, V 2min Indicates the minimum value of the voltage applied to the driving electrode when modulating the second incident light.

[0086] Each grating group corresponds to a grating period of the liquid crystal grating, and a plurality of driving electrodes in a grating group are applied with a gradient voltage (wherein the gradient voltage may be linear, which is not limited in the embodiment of the present invention), which can control the phase of the liquid crystal within the grating period to change from 0 to 2π. For example, Figure 12 A schematic diagram of a gradient voltage range applied to a driving electrode according to an embodiment of the present invention, wherein the central wavelength λ1 of the first incident light a is greater than the central wavelength λ2 of the second incident light b, and the gradient voltage range required to modulate the first incident light a is greater than the gradient voltage range required to modulate the second incident light b. By setting V 1min <V 2min , that is, increasing the voltage modulating the second incident light b is beneficial to improving the response speed of the liquid crystal. Figure 12 The horizontal axis represents the voltage V, and the vertical axis represents the phase change of the liquid crystal.

[0087] It should be noted that Figure 12 The V shown in 1min =0 is only for illustration and is not a limitation of the present invention. The specific implementation can be designed according to the actual situation. 1max and V 2max The value of is not limited, and is optional. The maximum voltage V applied to the driving electrode when modulating the first incident light 1max The maximum voltage V applied to the driving electrode when modulating the second incident light 2max Same or different, you can set V 1max Equal to V 2max , you can also set V 1max Greater or less than V 2max .

[0088] Optionally, the liquid crystal grating includes a plurality of grating groups, each grating group includes a plurality of driving electrodes, and when the liquid crystal grating modulates incident light, a gradient voltage is applied to the plurality of driving electrodes in the same grating group;

[0089] The voltage applied to the driving electrode satisfies:

[0090] V 1min <V 2min <V 3min ;

[0091] Where V 1min Indicates the minimum voltage applied to the driving electrode when modulating the first incident light, V 2min Indicates the minimum voltage loaded on the driving electrode when modulating the second incident light, V 3min Indicates the minimum value of the voltage applied to the driving electrode when modulating the third incident light.

[0092] Figure 13 A schematic diagram of another gradient voltage range applied to a driving electrode according to an embodiment of the present invention, wherein the first incident light, the second incident light, and the third incident light can be R, G, and B light, respectively. Since the gradient voltage ranges corresponding to the R, G, and B three-color light decrease in sequence, for the G / B subframe, the minimum voltage can be selected to be greater than 0V, for example, V 1min <V 2min <V 3min , in order to speed up the response speed of the liquid crystal. Figure 13 V is shown in 1min =0 is only an illustrative embodiment and is not a limitation of the present invention. In a specific implementation, optionally, the maximum voltage V applied to the driving electrode when modulating the first incident light is 1max , the maximum voltage V applied to the driving electrode when modulating the second incident light 2max The maximum voltage V applied to the driving electrode when modulating the third incident light 3max At least two of them may be the same or different, which is not limited in the embodiment of the present invention. Figure 13 The horizontal axis represents the voltage V, and the vertical axis represents the phase change of the liquid crystal.

[0093] In the aforementioned embodiment, by setting different modulation durations or changing the voltage of the driving electrode based on different modulation durations, in another embodiment, it may refer to changing the voltage of the driving electrode. Optionally, the liquid crystal grating includes multiple grating groups, each grating group includes multiple driving electrodes, and when the liquid crystal grating modulates the incident light, the multiple driving electrodes in the same grating group are loaded with a gradient voltage;

[0094] The first incident ray and the second incident ray satisfy:

[0095] λ1>λ2;

[0096] The voltage applied to the driving electrode satisfies:

[0097] V 1min <V 2min ;

[0098] Where λ1 represents the central wavelength of the first incident light, λ2 represents the central wavelength of the second incident light, and V 1min Indicates the minimum voltage applied to the driving electrode when modulating the first incident light, V 2min Indicates the minimum value of the voltage applied to the driving electrode when modulating the second incident light.

[0099] Optionally, the modulation duration satisfies:

[0100] t1=t2;

[0101] Wherein, t1 represents the modulation duration of the first incident light, and t2 represents the modulation duration of the second incident light.

[0102] Optionally, the incident light includes a first incident light, a second incident light, and a third incident light, and the first incident light, the second incident light, and the third incident light satisfy:

[0103] λ1>λ2>λ3;

[0104] The voltage applied to the driving electrode satisfies:

[0105] V 1min <V 2min <V 3min ;

[0106] Where λ1 represents the central wavelength of the first incident light, λ2 represents the central wavelength of the second incident light, λ3 represents the central wavelength of the third incident light, and V 1min Indicates the minimum voltage applied to the driving electrode when modulating the first incident light, V 2min Indicates the minimum voltage loaded on the driving electrode when modulating the second incident light, V 3min Indicates the minimum value of the voltage applied to the driving electrode when modulating the third incident light.

[0107] Optionally, the modulation duration satisfies:

[0108] t1=t2=t3;

[0109] Wherein, t1 represents the modulation time length of modulating the first incident light, t2 represents the modulation time length of modulating the second incident light, and t3 represents the modulation time length of modulating the third incident light.

[0110] The embodiment of only adjusting the voltage of the driving electrode is similar to the above embodiment and will not be described in detail here.

[0111] An embodiment of the present invention further provides a method for driving a liquid crystal grating, which is applicable to any of the liquid crystal gratings provided in the above embodiments. The liquid crystal grating includes multiple grating groups, each grating group includes multiple driving electrodes, wherein the odd-numbered driving electrodes in the same grating group are connected to the first signal terminal, the even-numbered driving electrodes are connected to the second signal terminal, and each driving electrode is connected to a corresponding driving voltage terminal.

[0112] For example, Figure 14 A schematic diagram of a circuit principle of a grating group provided by an embodiment of the present invention, referring to Figure 14 Optionally, the grating group includes a plurality of driving electrodes 20 ( Figure 14 (Six drive electrodes 20 are shown as an example, which is not a limitation of the embodiments of the present invention.) The grating group includes multiple first transistors 21 and multiple second transistors 22. The first end of the first transistor 21 is connected to the odd-numbered drive electrodes 20a in the same grating group, the second end of the first transistor 21 is connected to the first signal terminal Vrst1, and the control end of the first transistor 21 is connected to the first control signal terminal Rst1. The first end of the second transistor 22 is connected to the even-numbered drive electrodes 20b in the grating group, the second end of the second transistor 22 is connected to the second signal terminal Vrst2, and the control end of the second transistor 22 is connected to the second control signal terminal Rst2. To ensure the stability of the applied voltage, each drive electrode 20 is connected in parallel with a capacitor Cst.

[0113] Modulating the incident light includes a first stage of writing a corresponding modulation voltage to the driving electrode. The first stage includes a pre-charging stage and a gradient voltage writing stage. The driving method provided by the embodiment of the present invention includes:

[0114] In the pre-charging stage, the first signal terminal Vrst1 applies a first pre-charging voltage to the corresponding driving electrode, and the second signal terminal Vrst2 applies a second pre-charging voltage to the corresponding driving electrode.

[0115] That is, in the pre-charging stage, the first control signal terminal Rst1 controls the first transistor 21 to turn on, and the first signal terminal Vrst1 applies a first pre-charging voltage to the corresponding driving electrode. The second control signal terminal Rst2 controls the second transistor 22 to turn on, and the second signal terminal Vrst2 applies a second pre-charging voltage to the corresponding driving electrode, wherein the first pre-charging voltage is the same as the second pre-charging voltage and is the same as the minimum voltage value of the gradient voltage.

[0116] Continue to refer Figure 14Optionally, the grating group corresponds to a driving voltage terminal S, and the grating group also includes a plurality of third transistors 23, the first end of the third transistor 23 is connected to the driving electrode 20, the second end of the third transistor 23 is connected to the driving voltage terminal S, and the control end of the third transistor 20 is connected to the timing signal terminal CKH. In the gradient voltage writing stage, the driving voltage terminal S applies a gradient voltage to the corresponding driving electrode. In this stage, the first control signal terminal Rst1 controls the first transistor 21 to turn off, the second control signal terminal Rst2 controls the second transistor 22 to turn off, the timing signal terminal CKH controls the third transistor to turn on in sequence, and the driving voltage terminal S loads the driving voltage to the corresponding driving electrode. In other embodiments, the driving voltage terminal can also be set to correspond one to one with the corresponding driving electrode, and the number of driving electrodes in different grating groups can also be designed to be different according to actual needs. The specific implementation can be designed according to actual conditions.

[0117] Optionally, adjusting the incident light further includes a reset phase. During the reset phase, the first signal terminal Vrst1 applies a first reset voltage to the corresponding drive electrode, and the second signal terminal Vrst2 applies a second reset voltage to the corresponding drive electrode. That is, during the reset phase, the first control signal terminal Rst1 controls the conduction of the first transistor 20, and the first signal terminal Vrst1 applies the first reset voltage to the corresponding drive electrode. The second control signal terminal Rst2 controls the conduction of the second transistor 22, and the second signal terminal Vrst2 applies the second reset voltage to the corresponding drive electrode. The polarity of the first reset voltage is opposite to that of the second reset voltage. Adjusting the incident light further includes a reset phase, a precharge phase, and a gradient voltage writing phase, which are sequentially executed. Alternatively, adjusting the incident light further includes a precharge phase, a gradient voltage writing phase, and a reset phase, which are sequentially executed. By providing the reset phase, the influence of liquid crystal deflection in the previous frame can be eliminated.

[0118] For example, taking the example of adjusting the incident light including the reset stage, the pre-charge stage and the gradient voltage writing stage performed in sequence, Figure 15 A schematic diagram of the principle of applying voltage to a liquid crystal grating according to an embodiment of the present invention is provided. Figure 16 A timing diagram of a liquid crystal grating when a voltage is applied is provided in an embodiment of the present invention, with reference to Figure 15 In the figure, the horizontal axis is the position, and the vertical axis is the voltage V. In (a), a voltage reversal corresponds to an electrode, and in (c), the voltage from min to max corresponds to a grating group. Figure 16 , Figure 16The figure schematically illustrates four subframes f1 to f4 and the application of a gradient voltage to two drive electrodes D1 and D2. The horizontal axis represents time t, and the vertical axis represents voltage V. The second phase of the modulated incident light, i.e., the time for the liquid crystal to respond and maintain, is omitted. One subframe includes a reset phase (a), a precharge phase (b), and a gradient voltage writing phase (c). In other embodiments, the reset phase may be placed after the gradient voltage writing phase, and this can be selected based on actual circumstances during implementation.

[0119] Continue to refer Figure 16 Optionally, the polarity of each power-on signal is opposite in two adjacent modulation periods (i.e., two adjacent subframes). By setting the polarity of the power-on signals in two adjacent subframes to be reversed, it is possible to prevent the liquid crystal from being subjected to the same driving voltage for a long time, thereby affecting the driving effect.

[0120] Optionally, the voltage values of the first reset voltage and the second reset voltage are the same as the maximum voltage value of the gradient voltage. Directly using the maximum value of the gradient voltage as the reset voltage can ensure the reset effect, and the reset voltage terminal can also be shared with the drive voltage terminal, simplifying the circuit structure.

[0121] An embodiment of the present invention also provides a three-dimensional display device, comprising a backlight module, a spatial light modulator, and any one of the liquid crystal gratings provided in the above embodiments, which are stacked in sequence; the backlight module is used to provide the field-sequential collimated coherent backlight required for three-dimensional display; the spatial light modulator is used to modulate the phase and amplitude of the field-sequential collimated coherent backlight; and the liquid crystal grating is used to modulate the light beam output by the spatial light modulator into a first direction light beam and a second direction light beam and output them.

[0122] In a specific implementation, the backlight module includes a light source that emits three colors of RGB light. The spatial light modulator may include a phase liquid crystal spatial light modulator and an amplitude spatial light phase modulator. The liquid crystal grating may include one 0-degree and two 45-degree liquid crystal gratings. The first direction and the second direction are transmitted to the user's left eye and right eye, respectively. In other embodiments, a converging field lens disposed between the spatial light modulator and the liquid crystal grating may also be included. Since the three-dimensional display device provided by the embodiments of the present invention includes any of the liquid crystal gratings provided in the above embodiments, it has the same or corresponding technical effects as the liquid crystal grating and will not be described in detail here.

[0123] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the 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 and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A liquid crystal grating, characterized in that: Used to modulate the incident light and then output the deflected outgoing light; The incident light comprises at least a first incident light and a second incident light, the first incident light being modulated by the liquid crystal grating to output a first outgoing light, the second incident light being modulated by the liquid crystal grating to output a second outgoing light, and the wavelength band of the first incident light and the wavelength band of the second incident light at least partially not overlapping; When the liquid crystal grating modulates the first incident light and the second incident light, the central wavelength λ1 of the first incident light is greater than the central wavelength λ2 of the second incident light, the minimum value of the modulation voltage of the first incident light is less than the minimum value of the modulation voltage of the second incident light, and / or the modulation time t1 of the first incident light is greater than the modulation time t2 of the second incident light.

2. The liquid crystal grating according to claim 1, wherein The modulation period of the liquid crystal grating includes multiple subframes, and the modulation duration of one type of incident light corresponds to the duration of one subframe, wherein the end time of the Nth subframe is the same as the start time of the N+1th subframe, and N is an integer ≥2.

3. The liquid crystal grating according to claim 1, wherein Modulating the incident light includes a first stage and a second stage. In the first stage, a corresponding modulation voltage is written to the driving electrode of the liquid crystal grating. The first stage and the second stage satisfy: ； Among them, t 1a represents the duration of the first stage when modulating the first incident light, t 1b represents the duration of the second stage when modulating the first incident light, t 1b =t1-t 1a , t 2a represents the duration of the first stage when modulating the second incident light, t 2b represents the duration of the second stage when modulating the second incident light, t 2b =t2-t 2a .

4. The liquid crystal grating according to claim 3, wherein: t 1a =t 2a 。 5. The liquid crystal grating according to claim 1, wherein Modulating the incident light includes a first stage and a second stage. In the first stage, a corresponding modulation voltage is written to the driving electrode of the liquid crystal grating. The first stage satisfies: t 1a >t 2a ; The second stage meets the following requirements: t 1b >t 2b ; Among them, t 1a represents the duration of the first stage when modulating the first incident light, t 1b represents the duration of the second stage when modulating the first incident light, t 1b =t1-t 1a , t 2a represents the duration of the first stage when modulating the second incident light, t 2b represents the duration of the second stage when modulating the second incident light, t 2b =t2-t 2a .

6. The liquid crystal grating according to claim 1, wherein The incident light includes a first incident light, a second incident light and a third incident light, and the first incident light, the second incident light and the third incident light satisfy: λ1>λ2>λ3; The modulation duration satisfies: t1>t2, t1>t3; Among them, λ1 represents the central wavelength of the first incident light, λ2 represents the central wavelength of the second incident light, λ3 represents the central wavelength of the third incident light, t1 represents the modulation time of modulating the first incident light, t2 represents the modulation time of modulating the second incident light, and t3 represents the modulation time of modulating the third incident light.

7. The liquid crystal grating according to claim 6, wherein: t1>t2>t3.

8. The liquid crystal grating according to claim 7, wherein: Modulating the incident light includes a first stage and a second stage. In the first stage, a corresponding modulation voltage is written to the driving electrode of the liquid crystal grating. The first stage and the second stage satisfy: ； Among them, t 1a represents the duration of the first stage when modulating the first incident light, t 1b represents the duration of the second stage when modulating the first incident light, t 1b =t1-t 1a , t 2a represents the duration of the first stage when modulating the second incident light, t 2b represents the duration of the second stage when modulating the second incident light, t 3a represents the duration of the first stage when modulating the third incident light, t 2b =t2-t 2a , t 3b represents the duration of the second stage when modulating the third incident light, t 3b =t3-t 3a .

9. The liquid crystal grating according to claim 8, characterized in that: t 1a =t 2a =t 3a 。 10. The liquid crystal grating according to claim 7, wherein: Modulating the incident light includes a first stage and a second stage. In the first stage, a corresponding modulation voltage is written to the grating electrode of the liquid crystal grating. The first stage satisfies: t 1a >t 2a ≥t 3a ; The second stage meets the following requirements: t 1b >t 2b ≥t 3b ; Among them, t 1a represents the duration of the first stage when modulating the first incident light, t 1b represents the duration of the second stage when modulating the first incident light, t 1b =t1-t 1a , t 2a represents the duration of the first stage when modulating the second incident light, t 2b represents the duration of the second stage when modulating the second incident light, t 2b =t2-t 2a , t 3a represents the duration of the first stage when modulating the third incident light, t 3b represents the duration of the second stage when modulating the third incident light, t 3b =t3-t 3a .

11. The liquid crystal grating according to claim 1, wherein: The liquid crystal grating includes a plurality of grating groups, each of the grating groups includes a plurality of driving electrodes, and when the liquid crystal grating modulates the incident light, a gradient voltage is applied to the plurality of driving electrodes in the same grating group; The voltage applied to the driving electrode satisfies: In 1min <V 2min ; Where V 1min represents the minimum voltage applied to the driving electrode when modulating the first incident light, V 2min represents the minimum value of the voltage applied to the driving electrode when modulating the second incident light.

12. The liquid crystal grating according to claim 11, characterized in that The maximum voltage V applied to the driving electrode when modulating the first incident light 1max The maximum voltage V applied to the driving electrode when modulating the second incident light 2max Same or different.

13. The liquid crystal grating according to claim 6, characterized in that The liquid crystal grating includes a plurality of grating groups, each of the grating groups includes a plurality of driving electrodes, and when the liquid crystal grating modulates the incident light, a gradient voltage is applied to the plurality of driving electrodes in the same grating group; The voltage applied to the driving electrode satisfies: In 1min <V 2min <V 3min ; Where V 1min represents the minimum voltage applied to the driving electrode when modulating the first incident light, V 2min represents the minimum voltage applied to the driving electrode when modulating the second incident light, V 3min represents the minimum value of the voltage applied to the driving electrode when modulating the third incident light.

14. The liquid crystal grating according to claim 1, wherein The liquid crystal grating includes a plurality of grating groups, each of the grating groups includes a plurality of driving electrodes, and when the liquid crystal grating modulates the incident light, a gradient voltage is applied to the plurality of driving electrodes in the same grating group; The first incident light and the second incident light satisfy: λ1>λ2; The voltage applied to the driving electrode satisfies: In 1min <V 2min ; Wherein, λ1 represents the central wavelength of the first incident light, λ2 represents the central wavelength of the second incident light, V 1min represents the minimum voltage applied to the driving electrode when modulating the first incident light, V 2min represents the minimum value of the voltage applied to the driving electrode when modulating the second incident light.

15. The liquid crystal grating according to claim 14, characterized in that The modulation duration satisfies: t1=t2; Wherein, t1 represents the modulation duration of modulating the first incident light, and t2 represents the modulation duration of modulating the second incident light.

16. A method for driving a liquid crystal grating, characterized in that: The liquid crystal grating according to any one of claims 1 to 15, wherein the liquid crystal grating comprises a plurality of grating groups, each of the grating groups comprises a plurality of driving electrodes, wherein odd-numbered driving electrodes in the same grating group are connected to a first signal terminal, even-numbered driving electrodes are connected to a second signal terminal, and each driving electrode is connected to a corresponding driving voltage terminal; Modulating the incident light includes a first stage of writing a corresponding modulation voltage to the driving electrode, the first stage including a pre-charging stage and a gradient voltage writing stage; The driving method includes: In the pre-charging stage, the first signal terminal applies a first pre-charging voltage to the corresponding driving electrode, and the second signal terminal applies a second pre-charging voltage to the corresponding driving electrode; In the gradient voltage writing stage, the driving voltage end applies a gradient voltage to the corresponding driving electrode; The first pre-charge voltage is the same as the second pre-charge voltage and is the same as the minimum voltage value of the gradient voltage.

17. The driving method according to claim 16, wherein: Adjusting the incident light also includes a reset phase, in which the first signal terminal applies a first reset voltage to the corresponding driving electrode, and the second signal terminal applies a second reset voltage to the corresponding driving electrode, wherein the first reset voltage and the second reset voltage have opposite polarities; Adjusting the incident light includes sequentially executing the reset phase, the pre-charge phase, and the gradient voltage writing phase, or adjusting the incident light includes sequentially executing the pre-charge phase, the gradient voltage writing phase, and the reset phase.

18. The driving method according to claim 17, wherein: In two adjacent modulation time periods, the polarities of the power-on signals are opposite.

19. The driving method according to claim 17, wherein: Voltage values of the first reset voltage and the second reset voltage are the same as a maximum voltage value of the gradient voltage.

20. A three-dimensional display device, characterized in that: It comprises a backlight module, a spatial light modulator and the liquid crystal grating according to any one of claims 1 to 15 stacked in sequence; The backlight module is used to provide field sequential collimated coherent backlight required for three-dimensional display; The spatial light modulator is used to modulate the phase and amplitude of the field sequential collimated coherent backlight; The liquid crystal grating is used to modulate the light beam output by the spatial light modulator into a first direction light beam and a second direction light beam and output the modulated light beams.

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