Candid photographing prevention display device based on composite grating and control method

Abstract

The invention discloses an anti-candid photographing display device based on a composite grating and a control method, and relates to the technical field of optical display anti-counterfeiting, the anti-candid photographing display device comprises a display panel and a composite grating film; the composite grating film is arranged on the front side of the display panel. The technical problem to be solved by the invention is to provide a composite grating-based candid photographing prevention display device and a control method. The method comprises the following steps: generating gt during photographing of digital equipment; moire patterns with the signal-to-noise ratio of 45 dB are adopted, and candid shooting is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of optical display anti-counterfeiting, and in particular to an anti-secret-photography display device based on a composite grating and a control method. Background Art

[0002] With the development of electronic product technology, integrated cameras on mobile phones have become standard. However, this has also posed a threat to some companies or institutions to a certain extent, because anyone can use the camera function of their mobile phone to take photos anytime and anywhere. Therefore, preventing secret photography has become an important issue that needs to be solved.

[0003] Prior art, for example, a display device for preventing camera sneak shots, with the authorization announcement number CN213150177U, can prevent the displayed content from being secretly photographed by a camera and has a good anti-sneak shooting effect.

[0004] Currently, there is still a lack of an anti-secret photography display device that can generate moiré patterns with a signal-to-noise ratio of >45dB when shooting with a digital device, thereby preventing secret photography. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an anti-secret photography display device and control method based on a composite grating, so that a moiré pattern with a signal-to-noise ratio of >45dB is generated when a digital device is shooting, thereby preventing secret photography.

[0006] The present invention adopts the following technical solutions to achieve the invention objectives:

[0007] A composite grating-based anti-secret-photography display device is characterized by comprising: a display panel and a composite grating film;

[0008] The composite grating film is arranged on the front side of the display panel;

[0009] The spatial frequency f of the composite grating film and the pixel pitch P of the display panel satisfy:

[0010] f=k / P (1)

[0011] Among them: the value range of k is 1.05~1.25;

[0012] The angle θ between the grating stripes of the composite grating film and the horizontal direction satisfies:

[0013] θ=arctan(1 / m) (2)

[0014] Wherein: m is an integer from 2 to 4.

[0015] As a further limitation of the present technical solution, it further includes a control unit, and the display panel is electrically connected to the control unit.

[0016] As a further limitation of the present technical solution, a detection unit is installed on the display panel, and the detection unit is electrically connected to the control unit.

[0017] As a further limitation of the present technical solution, the composite grating film includes a microprism layer and a substrate arranged in sequence from front to back.

[0018] As a further limitation of the present technical solution, the prism height H of the micro-prism layer is 50-200 μm, and the prism period W is 0.8P-1.2P.

[0019] As a further limitation of the present technical solution, the refractive index n1 of the substrate and the refractive index n2 of the microprism layer satisfy: |n1-n2|≤0.02.

[0020] As a further limitation of the present technical solution, the composite grating film includes an electrically controlled liquid crystal grating layer, the electrically controlled liquid crystal grating layer is arranged in the microprism layer, the electrically controlled liquid crystal grating layer is electrically connected to the control unit, and the electrically controlled liquid crystal grating layer dynamically adjusts the spatial frequency f to the target value f under voltage control. t .

[0021] A control method for an anti-secret-photography display device based on a composite grating comprises the following steps:

[0022] S1: S1: detecting the position of the shooting device by the detection unit;

[0023] S2: Query the pre-stored database to obtain the CMOS pixel density of the camera;

[0024] S3: Calculate the target frequency according to formula (3);

[0025]

[0026] in: is the shooting angle of the camera detecting the shooting device, and is the normal angle between the detection unit and the shooting device;

[0027] S4: The control unit adjusts the voltage of the electrically controlled liquid crystal grating layer to generate a frequency f t .

[0028] As a further limitation of the present technical solution, the key geometric parameter of the composite grating film optical path design, angle β, represents the axial deviation angle of the diffracted light beam from the grating plane, and intuitively presents the light interaction mechanism of the electrically controlled liquid crystal grating layer and the substrate;

[0029] β=arctan(1 / m) (4).

[0030] As a further limitation of this technical solution, the core technical equation of the composite grating film interference principle is:

[0031] F m =F (5)

[0032] Among them: F m is the grating spatial frequency vector, which characterizes the inherent spatial periodicity of the composite grating film; its physical nature is determined by the prism period W and the tilt angle θ of the microprism layer;

[0033] F is the effective projection frequency vector, which represents the target frequency after dynamic adjustment;

[0034] |F m |=m1 / D (6)

[0035] D=d±Δd (7)

[0036] Where: d is the grating period, Δd is the change in the grating period that changes the arrangement of liquid crystal molecules under voltage regulation, and m1 represents the diffraction order, which is the order of the diffraction fringes produced after light passes through the grating. Here, it is set to 1.

[0037] |F|=nsinθ / λ (8)

[0038] Where: n represents the refractive index of the medium.

[0039] Compared with related technologies, the anti-secret-photography display device and control method based on a composite grating provided by the present invention have the following beneficial effects:

[0040] (1) The optical performance of the present invention is comprehensively improved: ultra-high transmittance and low color deviation: the composite grating film 200 precisely matches the refractive index of the microprism layer 201 with the refractive index of the substrate 202, and the prism period W and the pixel pitch P of the display panel 100 satisfy W=0.8P~1.2P, so that the central transmittance reaches 92.5%, which is 18.5-27.5% higher than the traditional anti-peep film (65-78%); the color deviation ΔE<1.5 (measured value 0.6), which is 92.5% lower than the existing technology (ΔE>8); in the OLED screen (P=78μm), the microprism layer (H=120μm, W=82μm) is combined with the PET substrate, and the measured human eye transmittance is 92%; enhanced anti-sneak photography effect: the grating spatial frequency f and the pixel pitch P satisfy f=k / P, the grating angle θ=arctan(1 / m), and the CMOS Bayer array RGB period is precisely matched. Actual measured results: Sony A7M4 generates 48.2dB signal-to-noise ratio moiré when shooting (>45dB target), far exceeding the industry standard.

[0041] (2) The dynamic adaptive capability innovation of the present invention: Intelligent environmental response: The electrically controlled liquid crystal grating layer 210 is combined with the control unit 300, which uses a camera to capture the device orientation, queries the CMOS database in real time and calculates the target frequency, and dynamically adjusts the voltage (3.2V) to change the arrangement of liquid crystal molecules.

[0042] (3) Revolutionary expansion of the viewing angle range of the present invention: Asymmetric viewing angle design: Through the core equation F m =F (grating natural frequency = effective projection frequency) to achieve dynamic matching, combined with β = arctan (1 / m) control, significantly expanding the viewing angle range: the measured range can reach 25-135° (traditional privacy film is only 28-42°), eliminating the "tunnel vision effect"; Physical mechanism: when the observation angle exceeds When the range is small, the transmittance drops sharply to <5%, achieving wide-area anti-peeping capability; Anti-angle deviation capability: The interference principle of the composite grating film 200 offsets the large-angle dispersion through the compensation term F_c (dispersion compensation frequency vector), ensuring that high-intensity moiré patterns are produced when the camera is secretly photographed at any angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The device structure of the present invention explodes Figure 1 .

[0044] Figure 2 The device structure of the present invention explodes Figure 2 .

[0045] Figure 3 This is the grating angle definition diagram of the present invention.

[0046] Figure 4 This is a block diagram of the electronic control system of the present invention.

[0047] In the figure: 100, display panel, 200, composite grating film, 201, microprism layer, 202, substrate, 210, electrically controlled liquid crystal grating layer, 300, control unit. DETAILED DESCRIPTION

[0048] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0049] See also Figures 1-4 The anti-secret-photography display device based on the composite grating of the present invention comprises:

[0050] It includes a display panel 100 and a composite grating film 200;

[0051] The composite grating film 200 is disposed on the front side of the display panel 100;

[0052] The spatial frequency f of the composite grating film 200 and the pixel pitch P of the display panel 100 satisfy:

[0053] f=k / P (1)

[0054] Among them: the value range of k is 1.05~1.25;

[0055] The angle θ between the grating stripes of the composite grating film 200 and the horizontal direction satisfies:

[0056] θ=arctan(1 / m) (2)

[0057] Wherein: m is an integer from 2 to 4, and m corresponds to the RGB period multiple of the CMOS Bayer array of the camera device.

[0058] The display panel 100 further includes a control unit 300 , and the display panel 100 is electrically connected to the control unit 300 .

[0059] A detection unit 400 is mounted on the display panel 100 , and the detection unit 400 is electrically connected to the control unit 300 .

[0060] The detection unit 400 is a camera.

[0061] The composite grating film 200 includes a microprism layer 201 and a substrate 202 arranged in sequence from front to back.

[0062] The prism height H of the micro-prism layer 201 is 50-200 μm, and the prism period W is 0.8P-1.2P.

[0063] The refractive index n1 of the substrate 202 and the refractive index n2 of the microprism layer 201 satisfy the following: |n1-n2|≤0.02.

[0064] The composite grating film 200 includes an electrically controlled liquid crystal grating layer 210, which is disposed within the microprism layer 201 and electrically connected to the control unit 300. The electrically controlled liquid crystal grating layer 210 can dynamically adjust the spatial frequency f to a target value f under voltage control. t , f t Calculated in real time based on the detected CMOS pixel density of the camera.

[0065] A control method for an anti-secret-photography display device based on a composite grating comprises the following steps:

[0066] S1: Detecting the position of the shooting device by the detection unit 400;

[0067] S2: Query the pre-stored database to obtain the CMOS pixel density of the camera;

[0068] S3: Calculate the target frequency according to formula (3);

[0069]

[0070] in: is the shooting angle of the camera detecting the shooting device, and is the normal angle between the detection unit and the shooting device;

[0071] S4: The control unit 300 adjusts the voltage of the electrically controlled liquid crystal grating layer 210 to generate a frequency f t .

[0072] The key geometric parameter of the optical path design of the composite grating film 200, angle β, represents the axial deviation angle of the diffracted light beam from the grating plane, and intuitively presents the light interaction mechanism between the electrically controlled liquid crystal grating layer 210 and the substrate 202;

[0073] β=arctan(1 / m) (4)

[0074] A quantitative relationship is established with the RGB period multiple of the CMOS Bayer array (m = integers from 2 to 4), and the β angle can be finely adjusted by controlling the m value.

[0075] As the m value increases, the β angle decreases (privacy protection is enhanced); as the m value decreases, the β angle increases (viewing angle is expanded).

[0076] Formula (4) is derived from the grating spatial frequency vector decomposition. When the composite grating has an orthogonal structure:

[0077]

[0078] Where: x =arctan(1 / m x ) is the axial deviation angle corresponding to the x-direction grating, and is the x-direction CMOS Bayer array period multiple (an integer from 2 to 4); β y =arctan(1 / m y ) is the axial deviation angle corresponding to the grating in the y direction, and is the period multiple of the CMOS Bayer array in the y direction (an integer from 2 to 4).

[0079] Since the deviation angles of the diffracted beams in the horizontal and vertical directions are perpendicular to each other, their combined deviation angles need to be calculated by vector synthesis to ensure that the β angle can still accurately reflect the privacy protection boundary (beyond the limit) at any shooting orientation (such as oblique shooting). range, that is, destructive interference occurs).

[0080] In the design of equal period grating (d x =d y =d), the components of its spatial frequency in the x and y directions are equal. Combining the principle of grating spatial frequency vector decomposition and the orthogonal structure characteristics of the composite grating, the following formula can be simplified:

[0081]

[0082] Technical implementation principle:

[0083] Working scenario:

[0084] Grating period: d = 82 μm (measured parameters); operating wavelength: λ = 550 nm (green light); shooting angle (Central visual area), combined with the grating diffraction principle and the structural characteristics of the composite grating, the diffraction geometric relationship is:

[0085]

[0086] Where: m1 represents the diffraction order.

[0087] It is necessary to consider the effect of the incident direction of light at this angle on diffraction, and introduce The term is used to correct the effect of angle deviation on optical path difference. This formula can accurately reflect the diffraction law of green light in the central visual area.

[0088] Engineering significance:

[0089] This angle β determines the key performance of anti-peeping characteristics and visual range:

[0090] Anti-peeping border control:

[0091] When the observation angle exceeds Range:

[0092] Destructive interference is enhanced → transmittance drops sharply (measured <5%).

[0093] The core technical equation of the interference principle of the composite grating film 200 is:

[0094] F m =F (5)

[0095] Among them: F m is the grating spatial frequency vector, which characterizes the inherent spatial periodicity of the composite grating film 200; its physical nature is determined by the prism period W and the tilt angle θ of the microprism layer 201;

[0096] The electrically controlled liquid crystal grating layer 210 changes the arrangement of liquid crystal molecules under voltage regulation (regulation voltage <5V, Δd = ±4μm), so that F can adapt to environmental requirements in real time;

[0097] The engineering significance of formula (5) is:

[0098] Anti-peeping performance guarantee: dynamic matching makes the grating natural frequency F mTracking F ensures high-intensity moiré patterns at any shooting angle, with a measured SNR > 45dB.

[0099] When the frequency of the light signal received by the CMOS sensor matches this equation, destructive interference occurs, causing the transmittance to drop sharply to <5%.

[0100] Viewing angle expansion mechanism: The compensation term F_c is used to offset large-angle dispersion and expand the field of view to 25-135° (traditional technology is only 28-42°).

[0101] Energy efficiency optimization basis: Only a small amount of voltage (measured energy consumption 14.8W) is required to achieve a fast response (3.1ms), because F m The matching accuracy with F reduces the ineffective light energy loss.

[0102] F is the effective projected frequency vector, which represents the target frequency after dynamic adjustment;

[0103] |F m |=m1 / D (6)

[0104] D=d±Δd (7)

[0105] Where: d is the grating period, Δd is the change in the grating period that changes the arrangement of liquid crystal molecules under voltage regulation, and m1 represents the diffraction order, which is the order of the diffraction fringes produced after light passes through the grating. Here, it is set to 1.

[0106] The basic period d=82 μm, the dynamic adjustment range Δd=±4 μm, and the diffraction order m=1 (main interference order).

[0107] |F|=nsinθ / λ (8)

[0108] Wherein: n represents the refractive index of the medium, specifically the refractive index of the microprism layer or substrate in the composite grating film, which is the core parameter affecting the optical interference and diffraction effects.

[0109] The device dynamically adjusts the compensation frequency to achieve the core mechanism of matching the total frequency with the shooting equipment requirements. The synthesis equation of the total frequency vector in the device's interference principle is:

[0110]

[0111] Where: F is the total effective frequency vector, which is the target frequency for matching the grating with the CMOS sensor of the camera device and is the core parameter that determines the anti-peeping and visible range; The frequency component related to the shooting angle is determined by the incident angle of the shooting device. F_c is the compensation frequency component, which is used to offset the error between the large angle dispersion or the grating natural frequency and the target frequency. The control unit 300 adjusts the electrically controlled liquid crystal grating layer 210 to generate the total frequency F and the grating natural frequency F. m 'Matching, thereby achieving a balance between dynamic anti-peeping (destructive interference) and viewing angle expansion (offsetting dispersion).

[0112] Dynamic balance process:

[0113] Initial state: λ = 550 nm;

[0114]

[0115] Grating intrinsic value d = 82 μm;

[0116] F m =1 / (82e-6)=12195m -1 ;

[0117] Error: ε = |12,195-11,925| = 270m -1

[0118] System Response:

[0119] The control chip calculates the compensation amount: F_c = +270m -1

[0120] Adjust the voltage to reduce the period: (Measured parameters match)

[0121] Striking a balance:

[0122] Technical implementation effect:

[0123] When F m =F:

[0124] Table 1 Technical Effects

[0125]

[0126]

[0127] Engineering significance

[0128] The equation F m =F is the core of the device's intelligent privacy protection:

[0129] 1. Dynamic matching: adjust Δd in real time to make F m Track F;

[0130] 2. Wide viewing angle guarantee: The compensation term F_c offsets large-angle dispersion (extended to 135°);

[0131] 3. Energy efficiency optimization: Only a small amount of voltage (<5V) is required to achieve Δd = ±4μm adjustment (measured energy consumption 14.8W)

[0132] Specifically, the orientation change of liquid crystal molecules (such as liquid crystal materials such as Merck E7) is controlled by electrodes, so that the physical structure of the grating undergoes a displacement adjustment of Δd=±4μm.

[0133] Example 1: Static grating film structure

[0134] The display panel 100 adopts a 4K OLED screen with a pixel pitch P=78 μm.

[0135] The composite grating film 200 includes a microprism layer 201 and a substrate 202 .

[0136] The micro-prism layer 201 is made of ultraviolet curing resin (n2=1.53), with a prism height H=120 nm and a period W=82 μm (k=1.05).

[0137] The substrate 202 is made of PET film (n1=1.51) with a thickness of 0.1 mm.

[0138] The grating inclination angle θ=18.4° (m=3, corresponding to 3 times the RGB period).

[0139] When photographing with a Sony A7M4 camera, the image achieved a signal-to-noise ratio (SNR) of 48.2dB (Imatest test), a human eye transmittance of 92%, and a color shift ΔE < 1.5 (CIE Lab standard).

[0140] Example 2: Dynamically electrically controlled grating

[0141] The electrode spacing of the electrically controlled liquid crystal grating layer 210 is 40 μm, and the liquid crystal material is Merck E7. The experimental data are shown in Table 2.

[0142] Table 2 Dynamic electric controlled grating experimental data

[0143]

[0144]

[0145] The working principle of the anti-secret-photography display device and control method based on a composite grating provided by the present invention is as follows:

[0146] The camera is mounted on the display panel 100. The control unit includes a processor, a D / A conversion module and liquid crystal electrodes, and the control unit stores a CMOS database in advance.

[0147] The camera detects the position of the shooting device.

[0148] The pre-stored CMOS database is queried to obtain the CMOS pixel density of the shooting device.

[0149] The D / A conversion module converts the digital signal into an analog signal, and the processor controls the liquid crystal electrode to generate a 3.2V voltage, so that the electrically controlled liquid crystal grating layer 210 generates a frequency f t .

[0150] The optical performance of the present invention is comprehensively improved:

[0151] Ultra-high light transmittance and low color shift:

[0152] By precisely matching the refractive index of the microprism layer 201 with that of the substrate 202, and ensuring that the prism period W and the pixel pitch P of the display panel 100 satisfy W = 0.8P to 1.2P, the composite grating film 200 achieves a central light transmittance of 92.5%, an 18.5-27.5% improvement over traditional privacy films (65-78%). The color shift, ΔE, is less than 1.5 (measured value 0.6), a 92.5% reduction compared to existing technologies (ΔE > 8).

[0153] In the OLED screen (P=78μm), the microprism layer (H=120nm, W=82μm) is combined with the PET substrate, and the measured human eye transmittance is 92%.

[0154] Enhanced anti-secret photography effect:

[0155] The grating spatial frequency f and pixel pitch P satisfy f = k / P, and the grating angle θ = arctan (1 / m), precisely matching the RGB period of the CMOS Bayer array. Actual results: When shooting on a Sony A7M4, moiré patterns are generated at a 48.2dB signal-to-noise ratio (>45dB target), far exceeding the industry standard.

[0156] The dynamic adaptive capability innovation of the present invention:

[0157] Intelligent environmental response:

[0158] The electrically controlled liquid crystal grating layer 210 is combined with the control unit 300 to capture the device orientation through a camera, query the CMOS database in real time and calculate the target frequency, and dynamically adjust the voltage (3.2V) to change the arrangement of liquid crystal molecules.

[0159] Scenario example: The in-vehicle environment supports day and night mode switching - day mode (β = 4.8°, standard anti-peeping) and night mode (β = 12.6°, viewing angle expanded to 64°, transmittance 88.2%); β angle compensation accuracy is ±0.3° under 5-15Hz vibration, and the resolution retention rate is 99.3%.

[0160] Millisecond optical response:

[0161] Material innovation: Using ferroelectric liquid crystal (such as Merck E7) to achieve μs-level molecular flipping, the device response time is as low as 3.1ms (traditional mechanical dimming >500ms), and the refresh rate is 144Hz (meeting ≥85Hz requirements).

[0162] Energy consumption optimization: voltage adjustment range <5V (Δd=±4μm), measured energy consumption is only 14.8W (standard ≤20W).

[0163] The present invention revolutionizes the viewing angle range:

[0164] Asymmetric field of view design:

[0165] Through the core equation F m =F (grating natural frequency = effective projection frequency) to achieve dynamic matching, combined with β = arctan (1 / m) control, significantly expanding the viewing angle range: the measured range can reach 25-135° (traditional anti-peep film is only 28-42°), eliminating the "tunnel vision effect".

[0166] Physical mechanism: When the observation angle exceeds When the light transmittance drops sharply to less than 5% in the wide-area anti-peeping range, the light transmittance drops sharply to less than 5%, achieving wide-area anti-peeping

[0167] Anti-angle deviation ability:

[0168] The interference principle of the composite grating film 200 offsets large-angle dispersion through the compensation term F_c (dispersion compensation frequency vector), ensuring that high-intensity moiré patterns are produced when the camera is secretly photographed at any angle.

[0169] Industrial adaptability and reliability of the present invention:

[0170] Simplified structure: The composite grating film 200 only requires a double-layer structure of a microprism layer 201 and a substrate 202 , and the production process is compatible with existing display modules.

[0171] Stability verification (as shown in Table 1):

[0172] Angle detection accuracy ±0.9° (standard ≤3°);

[0173] Color accuracy ΔE = 1.2 (standard ≤ 3.0);

[0174] Viewing angle range 25-135° (standard 40-120°).

[0175] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An anti-secret-photography display device based on a composite grating, characterized in that: include: It comprises a display panel (100) and a composite grating film (200); The composite grating film (200) is arranged on the front side of the display panel (100); The spatial frequency f of the composite grating film (200) and the pixel pitch P of the display panel (100) satisfy: f=k / P (1) Among them: the value range of k is 1.05~1.25; The angle θ between the grating stripes of the composite grating film (200) and the horizontal direction satisfies: θ=arctan(1 / m) (2) Wherein: m is an integer from 2 to 4.

2. The anti-secret-photography display device based on a composite grating according to claim 1 is characterized in that: It also includes a control unit (300), and the display panel (100) is electrically connected to the control unit (300).

3. The anti-secret-photography display device based on a composite grating according to claim 2, characterized in that: A detection unit (400) is installed on the display panel (100), and the detection unit (400) is electrically connected to the control unit (300).

4. The anti-secret-photography display device based on a composite grating according to claim 3 is characterized in that: The composite grating film (200) comprises a microprism layer (201) and a substrate (202) which are sequentially arranged from front to back.

5. The anti-secret-photography display device based on a composite grating according to claim 4 is characterized in that: The prism height H of the micro-prism layer (201) is 50-200 μm, and the prism period W is 0.8P-1.2P.

6. The anti-secret-photography display device based on a composite grating according to claim 4, characterized in that: The refractive index n1 of the substrate (202) and the refractive index n2 of the microprism layer (201) satisfy: |n1-n2|≤0.

02.

7. The anti-secret-photography display device based on a composite grating according to claim 4, characterized in that: The composite grating film (200) comprises an electrically controlled liquid crystal grating layer (210), the electrically controlled liquid crystal grating layer (210) being arranged in the microprism layer (201), the electrically controlled liquid crystal grating layer (210) being electrically connected to the control unit (300), and the electrically controlled liquid crystal grating layer (210) dynamically adjusting the spatial frequency f to a target value f under voltage control. t .

8. The control method of the anti-secret-photography display device based on the composite grating according to claim 7 is characterized in that: The following steps are involved: S1: detecting the position of the photographing device by the detection unit (400); S2: Query the pre-stored database to obtain the CMOS pixel density of the camera; S3: Calculate the target frequency according to formula (3); in: is the shooting angle of the camera detecting the shooting device, and is the normal angle between the detection unit and the shooting device; S4: The control unit (300) adjusts the voltage of the electrically controlled liquid crystal grating layer (210) to generate a frequency f t .

9. The control method according to claim 8, characterized in that: The key geometric parameter β angle of the optical path design of the composite grating film (200) represents the axial deviation angle of the diffracted light beam from the grating plane, and intuitively presents the light interaction mechanism of the electrically controlled liquid crystal grating layer (210) and the substrate (202); β=arctan(1 / m) (4).

10. The control method according to claim 9, characterized in that: The core technical equation of the interference principle of the composite grating film (200) is: F m =F (5) Among them: F m is a grating spatial frequency vector, characterizing the inherent spatial periodicity of the composite grating film (200); its physical nature is determined by the prism period W and the tilt angle θ of the microprism layer (201); F is the effective projection frequency vector, which represents the target frequency after dynamic adjustment; |F m |=m1 / D (6) D=d±Δd (7) Where: d is the grating period, Δd is the change in the grating period that changes the arrangement of liquid crystal molecules under voltage regulation, and m1 represents the diffraction order; |F|=n sinθ / λ (8) Where: n represents the refractive index of the medium.

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