Design method of dual-CLC cooperative filtering switching device adaptive to wide viewing angle and day and night monitoring intelligent camera

Abstract

The invention discloses a design method of a dual-CLC cooperative filtering switching device adaptive to a wide visual angle and a day and night monitoring intelligent camera, through cooperative design of a left-handed CLC sheet and a right-handed CLC sheet, the left-handed CLC sheet and the right-handed CLC sheet respectively reflect left-handed circularly polarized light and right-handed circularly polarized light of a wave band A in a targeted manner to form full-polarization-state coverage, and the full-polarization-state coverage is realized; meanwhile, the band-pass characteristics of the CLC sheet and the double-band-pass filter film are accurately matched in combination with an optimization problem, the effective visual angle of the filter switching device is effectively widened on the basis of ensuring that the light transmittance meets the optical requirement, the problems of matching failure and stray light interference under the large visual angle of a traditional CLC structure are thoroughly solved, and the large-visual-field coverage requirement of wide-visual-angle monitoring is met.

Description

Technical Field

[0001] This invention relates to the field of optical filtering device technology, specifically to a design method for a dual cholesteric liquid crystal (CLC) cooperative filtering switching device adapted to a wide viewing angle and a day / night monitoring smart camera. The filtering switching device of this invention is applicable to optical systems that require precise switching between day and night bands under wide viewing angle conditions, such as day / night monitoring smart cameras, infrared imaging devices, and smart display terminals. Background Technology

[0002] Traditional cameras employ switchable IRCUT mechanisms to block infrared light during the day and transmit it at night. This mechanical structure is bulky and prone to motor damage. Researchers have designed a cholesteric phase light valve with specific reflection wavelengths and bandwidths, paired with a dual-bandpass filter for visible light and 850nm wavelengths. When the cholesteric phase light valve is de-energized, it reflects light near 850nm, while the dual-bandpass filter allows both visible and near-850nm wavelengths to pass through. In this state, all light except visible light is blocked, making it suitable for daytime shooting. When the cholesteric phase light valve is energized, both visible and near-infrared light are transmitted, making it suitable for nighttime shooting with infrared illumination.

[0003] However, in practical applications, the reflectance wavelength of cholesteric liquid crystals is limited by material properties, resulting in a narrow range of high reflectivity wavelengths, making it difficult to achieve precise coverage across a wide band. Furthermore, in wide-angle incident scenarios, the reflectance wavelength of cholesteric liquid crystals shifts significantly to the left. To ensure a high infrared cutoff rate in daytime mode, the near-infrared bandpass region of the dual bandpass filter must be precisely matched to the high reflectivity wavelength range of the cholesteric phase. The matching accuracy directly affects the filtering effect. At the same time, due to limitations in coating materials and processes, the bandpass region of the dual bandpass filter also shifts to the left at wide angles, but the degree of left shift differs from that of the cholesteric liquid crystal. This causes the optimal matching state at 0° angle to fail at wide angles, resulting in problems such as decreased infrared cutoff rate and increased stray light interference, which cannot meet the usage requirements of wide-angle monitoring scenarios. Summary of the Invention

[0004] The purpose of this invention is to propose a design method for a dual CLC collaborative filter switching device adapted to a wide viewing angle and a smart camera for day and night monitoring. Through the collaborative design of left-handed and right-handed CLC sheets, they respectively target the reflection of left-handed and right-handed circularly polarized light in band A, forming full polarization coverage. At the same time, by combining optimization problems to accurately match the bandpass characteristics of the CLC sheet and the dual bandpass filter film, the effective viewing angle of the filter switching device is effectively widened while ensuring that the transmittance meets the optical requirements. This completely solves the problems of matching failure and stray light interference in the large viewing angle of traditional CLC structures, and meets the large field of view coverage requirements of wide-view monitoring.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention discloses a design method for a dual CLC cooperative filter switching device adapted to a wide viewing angle. The filter switching device includes a dual bandpass filter (1), a left-handed CLC plate (2), and a right-handed CLC plate (3) stacked sequentially. The left-handed CLC plate (2) and the right-handed CLC plate (3) are connected to a driving circuit via electrodes. The driving circuit is used to control the power supply of the left-handed CLC plate (2) and the right-handed CLC plate (3). The dual bandpass filter (1) allows band A and band B to pass through. The left-handed CLC plate (2) is configured such that when the power is off... The reflection band A contains left-handed circularly polarized light, and the transmission band A contains right-handed circularly polarized light. The right-handed CLC plate (3) is configured such that when the power is off, the reflection band A contains right-handed circularly polarized light, and the transmission band A contains left-handed circularly polarized light. When the left-handed CLC plate (2) and the right-handed CLC plate (3) are powered on, both band A and band B are allowed to pass through. An infrared supplementary light is also provided in front of the filter switching device. The infrared supplementary light is connected to the driving circuit. When the driving circuit powers the left-handed CLC plate (2) and the right-handed CLC plate (3), it simultaneously powers the infrared supplementary light. Band A is the near-infrared band.

[0007] The method includes the following steps:

[0008] S1. Determine the infrared filler lamp model based on band A, extract the spectral function of the infrared filler lamp, and set the target center reflection wavelength range of the CLC sheet based on the relative radiation intensity.

[0009] S2. Construct a cholesteric liquid crystal reflectance characteristic testing platform. For the CLC sheet placed on it, collect reflectance spectra corresponding to different target center reflection wavelengths. Based on a preset reflectance threshold, extract high reflectance bands and remove target center reflection wavelengths that do not cover band A to obtain the corrected range of target center reflection wavelengths for the CLC sheet. Simultaneously, a correlation function between the high reflectivity wavelength and the target center reflection wavelength is established. To obtain the permissible reflection wavelength range ;

[0010] S3, according to the first preset step size, from the allowable reflection wavelength range Several reflection wavelengths to be fitted are selected, and the reflection wavelength shift of the CLC sheet at various viewing angles is tested for different reflection wavelengths to be fitted. The reflection wavelength shift is then fitted to obtain the result. With the reflected wavelength Perspective The coupling relationship function;

[0011] S4, according to the second preset step size, the wavelength range of the reflection from the target center is selected. Select several reflection wavelengths to be tested The corresponding high reflectivity band is obtained. And the second left shift at the maximum and minimum viewing angles. and ;

[0012] S5. For different target center reflection wavelengths, using the corresponding high reflectivity band as the maximum limiting range, and taking band A as the target filtering band, several models of dual bandpass filters are selected, and the effective filtering wavelength range of each dual bandpass filter model is obtained according to the preset transmittance threshold. The transmittance of the dual-bandpass filter within the effective filtering wavelength range was measured. and the central reflection wavelength is The reflectivity of CLC film And the first left shift of the dual bandpass filter at the maximum and minimum viewing angles. and , j represents the j-th filter film;

[0013] S6. With the constraint that the product of the transmittance of each wavelength in band A at 0° and maximum viewing angles for the CLC film and dual bandpass filter in the power-off state is less than their respective minimum allowable transmittance thresholds, and with the optimization objectives of minimizing the relative left shift between the dual bandpass filter and the CLC film, minimizing the total transmittance of the CLC film and dual bandpass filter in the power-off state within the effective filtering wavelength range, and maximizing the total light transmission efficiency of the CLC film and dual bandpass filter in the power-on state within the effective filtering wavelength range, an optimization problem is constructed. The optimization problem is solved to select the optimal target center reflection wavelength of the CLC film and the optimal filter film model from the target center reflection wavelength range.

[0014] Furthermore, band B is the visible light band.

[0015] Furthermore, in step S6, the optimization problem is:

[0016]

[0017] In the formula, and The center reflection wavelengths in the power-off state are respectively... The wavelength of CLC film at the minimum and maximum viewing angles The corresponding reflectivity, This indicates the maximum viewing angle of the filter switching device. and These represent the wavelengths of the selected j-th filter at the minimum and maximum viewing angles, respectively. Corresponding transmittance; and These represent the wavelengths at the minimum and maximum viewing angles, respectively. The corresponding weighting factor is affected by the photosensitivity of the photosensitive device to wavelength; This indicates the wavelength of a CLC sheet in its energized state at its minimum viewing angle. The corresponding transmittance, and These are the weighting factors for the minimum and maximum viewing angles, respectively, in transmission mode; This represents the light intensity curve of the infrared supplementary light. and These represent the minimum permissible transmittance thresholds when power is off and when power is on, respectively. and These are the maximum allowable relative offsets at the minimum and maximum viewing angles, respectively. It represents the minimum total transmittance at the smallest viewing angle under perspective conditions; and These are the minimum and maximum wavelengths of band A, respectively;

[0018] The optimal target center reflection wavelength and the optimal filter film model for the CLC film are selected from the range of target center reflection wavelength values ​​by obtaining the optimization model.

[0019] Furthermore, the method also includes:

[0020] The reflection wavelength of the CLC sheet at different voltages was tested, and the relationship function between voltage and target center reflection wavelength was obtained by fitting. The target center reflection wavelength was adjusted by adjusting the voltage.

[0021] Furthermore, the method also includes:

[0022] By combining the scene light environment of the filter switching device, the target wavelength of different scene light environments is obtained, and the number of CLC sheet combinations and the reflection wavelength of different CLC sheets are set accordingly. Each CLC sheet combination corresponds to a working mode of a scene light environment.

[0023] Select the appropriate bandpass filter according to the target band so that the effective filtering wavelength range of the bandpass filter covers all target bands;

[0024] For different lighting environments, an optimization problem is constructed with the constraint that the transmittance of the CLC sheet combination and bandpass filter in the power-off state is less than the minimum allowable transmittance threshold for each wavelength in the target band at both the minimum and maximum viewing angles. The optimization objectives are to minimize the total transmittance of the CLC sheet combination and bandpass filter in the power-off state within the effective filter wavelength range and maximize the total light transmission efficiency of the CLC sheet combination and bandpass filter in the power-on state in the corresponding target band. The optimization problem is solved by selecting the optimal target center reflection wavelength and the optimal filter film model for each CLC sheet combination from the range of target center reflection wavelength values.

[0025] Furthermore, the scene lighting environment is set according to the ambient light intensity and is divided into nighttime, dawn / dusk, and daytime.

[0026] Secondly, the present invention discloses a day and night monitoring smart camera, which uses a filter switching device as described above, including a camera body, and the filter switching device is installed at the front end of the camera body.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] First, the design method of the dual CLC cooperative filter switching device and the day and night monitoring smart camera adapted to wide viewing angle of the present invention, by reasonably designing the reflection wavelength of the cholesteric phase and the bandpass wavelength of the dual bandpass filter film, ensures the cutoff rate of the target band light in the reflection mode and the high LED energy utilization rate in the transmission mode, solves the problems of matching failure and stray light interference in the traditional CLC structure under wide viewing angle, and meets the wide field of view coverage requirements of wide viewing angle monitoring.

[0029] Secondly, the design method of the dual CLC collaborative filter switching device and the day / night monitoring smart camera adapted to a wide viewing angle of the present invention utilize the electrochromic properties of cholesteric liquid crystals, eliminating the need for the motor-driven mechanical structure of the IRCUT and fundamentally avoiding the defects of mechanical wear, jamming, and short lifespan. The collaborative design of the dual CLC layers further improves structural redundancy. Even if a single CLC layer experiences slight performance degradation, the other layer can still ensure the core filter function, improving the reliability of continuous operation of the device and making it suitable for long-term operation scenarios such as outdoor monitoring.

[0030] Third, the design method of the dual CLC cooperative filter switching device and the day and night monitoring smart camera adapted to the wide viewing angle of the present invention can optimize the problem by flexibly selecting the optimal target center reflection wavelength and filter model according to the spectral characteristics of the infrared supplement light and the viewing angle requirements of the actual installation scene, so as to adapt to day and night monitoring smart cameras of different specifications. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the day / night filter switching device.

[0032] Figure 2 Flowchart of the design method for a dual CLC cooperative filter switching device adapted to a wide viewing angle. Detailed Implementation

[0033] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0034] This invention discloses a design method for a dual CLC cooperative filter switching device adapted to a wide viewing angle, see [link to relevant documentation]. Figure 1 The filter switching device includes a dual bandpass filter 1, optical adhesive 4, left-handed CLC 2, optical adhesive 4, and right-handed CLC 3 stacked sequentially.

[0035] The dual-bandpass filter 1 can be a coating or a lens. The characteristics of the dual-bandpass filter 1 are: it allows visible light (e.g., 400~700nm) and near-infrared light (e.g., 800~900nm) to pass through, while blocking other bands. The left-handed CLC2 and right-handed CLC3 are designed for near-infrared reflection bands.

[0036] The characteristics of the filter switching device are:

[0037] Power-on state: Allows visible and near-infrared light to pass through, while other wavelengths are blocked.

[0038] Power off state: Only visible light is allowed to pass through, other wavelengths are blocked.

[0039] The following explains the working principles of left-handed CLC2 and right-handed CLC3:

[0040] When CLC2 and right-handed CLC3 are energized: the strong electric field forces the two CLC layers into a uniform transparent state, losing polarization selectivity and reflectivity.

[0041] Power off (voltage returns to zero): The electric field disappears, and the two CLC layers relax back to the plane state, restoring their inherent selective reflection capability for light of specific wavelengths and directions.

[0042] CLC pitch design: When the two CLC layers are in a planar state, their reflection bands precisely cover the near-infrared band (left-handed CLC reflects left-handed light, right-handed CLC reflects right-handed light), while being transparent to the visible light band.

[0043] The polarization combination "switch" of the double CLC layer:

[0044] When power is off (planar state), the two CLC layers with opposite rotation directions combine to act as a "circularly polarization-independent" mirror / optical shutter for the 800-900nm wavelength band. Regardless of the polarization state of the incident near-infrared light, its left-handed component is reflected by the first layer, and its right-handed component is reflected by the second layer, effectively blocking (cutting off) that wavelength band. Visible light, however, is unobstructed.

[0045] When powered on (uniform state), both CLC layers become transparent "windows", allowing visible light and near-infrared light allowed by the filter to pass through freely.

[0046] Based on this structure, see Figure 2 The method includes the following steps:

[0047] S1. Determine the infrared filler lamp model based on band A, extract the spectral function of the infrared filler lamp, and set the target center reflection wavelength range of the CLC sheet based on the relative radiation intensity.

[0048] S2. Construct a cholesteric liquid crystal reflectance characteristic testing platform. For the CLC sheet placed on it, collect reflectance spectra corresponding to different target center reflection wavelengths. Based on a preset reflectance threshold, extract high reflectance bands and remove target center reflection wavelengths that do not cover band A to obtain the corrected range of target center reflection wavelengths for the CLC sheet. Simultaneously, a correlation function between the high reflectivity wavelength and the target center reflection wavelength is established. To obtain the permissible reflection wavelength range ;

[0049] S3, according to the first preset step size, from the allowable reflection wavelength range Several reflection wavelengths to be fitted are selected, and the reflection wavelength shift of the CLC sheet at various viewing angles is tested for different reflection wavelengths to be fitted. The reflection wavelength shift is then fitted to obtain the result. With the reflected wavelength Perspective The coupling relationship function;

[0050] S4, according to the second preset step size, the wavelength range of the reflection from the target center is selected. Select several reflection wavelengths to be tested The corresponding high reflectivity band is obtained. And the second left shift at the maximum and minimum viewing angles. and ;

[0051] S5. For different target center reflection wavelengths, using the corresponding high reflectivity band as the maximum limiting range, and taking band A as the target filtering band, several models of dual bandpass filters are selected, and the effective filtering wavelength range of each dual bandpass filter model is obtained according to the preset transmittance threshold. The transmittance of the dual-bandpass filter within the effective filtering wavelength range was measured. and the central reflection wavelength is The reflectivity of CLC film And the first left shift of the dual bandpass filter at the maximum and minimum viewing angles. and , j represents the j-th filter film;

[0052] S6. With the constraint that the product of the transmittance of each wavelength in band A at 0° and maximum viewing angles for the CLC film and dual bandpass filter in the power-off state is less than their respective minimum allowable transmittance thresholds, and with the optimization objectives of minimizing the relative left shift between the dual bandpass filter and the CLC film, minimizing the total transmittance of the CLC film and dual bandpass filter in the power-off state within the effective filtering wavelength range, and maximizing the total light transmission efficiency of the CLC film and dual bandpass filter in the power-on state within the effective filtering wavelength range, an optimization problem is constructed. The optimization problem is solved to select the optimal target center reflection wavelength of the CLC film and the optimal filter film model from the target center reflection wavelength range.

[0053] This step is achieved by constructing an optimization model, and the optimization problem is:

[0054]

[0055] In the formula, and The center reflection wavelengths in the power-off state are respectively... The wavelength of CLC film at the minimum and maximum viewing angles The corresponding reflectivity, This indicates the maximum viewing angle of the filter switching device. and These represent the wavelengths of the selected j-th filter at the minimum and maximum viewing angles, respectively. Corresponding transmittance; and These represent the wavelengths at the minimum and maximum viewing angles, respectively. The corresponding weighting factor is affected by the photosensitivity of the photosensitive device to wavelength; This indicates the wavelength of a CLC sheet in its energized state at its minimum viewing angle. The corresponding transmittance, and These are the weighting factors for the minimum and maximum viewing angles, respectively, in transmission mode; This represents the light intensity curve of the infrared supplementary light. and These represent the minimum permissible transmittance thresholds when power is off and when power is on, respectively. and These are the maximum allowable relative offsets at the minimum and maximum viewing angles, respectively. It represents the minimum total transmittance at the smallest viewing angle under perspective conditions; and These are the minimum and maximum wavelengths of band A, respectively. An optimization problem is solved to select the optimal target center reflection wavelength and the optimal filter type for the CLC sheet. To achieve wide-viewing-angle processing, this invention simultaneously sets optimization objectives for both the relative left shift and the transmittance requirements in different modes. This ensures a high cutoff rate for the target band light in reflection mode and high LED energy utilization in transmission mode, solving the problems of matching failure and stray light interference in traditional CLC structures under wide viewing angles, and meeting the large field-of-view coverage requirements for wide-viewing-angle monitoring.

[0056] As a preferred example, the relationship between voltage and the target center reflection wavelength can be obtained by testing the reflection wavelength of the CLC sheet at different voltages. Based on this, the target center reflection wavelength can be adjusted by adjusting the voltage. During the later maintenance of the filter switching device, when the filter ages or needs to be replaced, resulting in the need to fine-tune the reflection band of the CLC sheet, the reflection band of the CLC sheet can be quickly matched with the filter by adjusting the driving voltage, without having to replace the CLC sheet at the same time.

[0057] As a preferred example, the present invention also proposes an application example of a more complex filter switching device. The details are as follows:

[0058] By combining the scene light environment of the filter switching device, the target wavelength of different scene light environments is obtained, and the number of CLC sheet combinations and the reflection wavelength of different CLC sheets are set accordingly. Each CLC sheet combination corresponds to a working mode of a scene light environment.

[0059] Select the appropriate bandpass filter according to the target band so that the effective filtering wavelength range of the bandpass filter covers all target bands;

[0060] For different lighting environments, an optimization problem is constructed with the constraint that the transmittance of the CLC sheet combination and bandpass filter in the power-off state is less than the minimum allowable transmittance threshold for each wavelength in the target band at both the minimum and maximum viewing angles. The optimization objectives are to minimize the total transmittance of the CLC sheet combination and bandpass filter in the power-off state within the effective filter wavelength range and maximize the total light transmission efficiency of the CLC sheet combination and bandpass filter in the power-on state in the corresponding target band. The optimization problem is solved by selecting the optimal target center reflection wavelength and the optimal filter film model for each CLC sheet combination from the range of target center reflection wavelength values.

[0061] As mentioned above, the design method proposed in this invention can be further extended to multi-target band applications, thereby enabling the filter switching device to adapt to the optical control requirements of different optical devices.

[0062] For example, when a filter switching device is applied to a day / night surveillance smart camera, it is usually set to have two working modes: day and night. The control logic of the day / night surveillance smart camera is as follows:

[0063] Daytime mode: The filter switching device is powered off, allowing only visible light to pass through, avoiding infrared interference.

[0064] Night mode: When the filter switching device is powered on, the infrared fill light is turned on simultaneously, and the night vision effect is enhanced by the use of both visible and near-infrared light.

[0065] However, in practical applications, the lighting is dim at dawn and dusk. Simply switching modes based on the ambient light threshold can easily lead to insufficient light or severe infrared interference at these times, resulting in a decrease in image quality. Therefore, this invention can set up two or more CLC combinations, combined with supplementary lights of different spectra, to meet the lighting adjustment needs of different modes.

[0066] This situation also exists in fields such as intelligent vehicle vision systems, UAV multispectral reconnaissance equipment, and intelligent building light-controlled glass. Specifically, for intelligent vehicle vision systems, different scene lighting environments can be set according to actual application needs, such as nighttime driving (streetlights + vehicle lights), tunnel switching (light-dark transition), daytime strong light (direct sunlight), and rainy / foggy days (diffuse light). Four sets of CLCs are combined to correspond to the four types of scenes, and the bandpass filter covers the visible light and near-infrared transmission bands. For UAV multispectral reconnaissance equipment, low-altitude reconnaissance (strong light) can be set. For different lighting environments such as high-altitude reconnaissance (weak light + atmospheric scattering) and nighttime reconnaissance (infrared supplementary light), three sets of CLCs are used to correspond to three types of bands, and the bandpass filter covers the 400~1100nm multispectral range. For smart building light-controlled glass, lighting environments such as early morning (low-angle strong light), noon (direct strong light), evening (warm light), and night (indoor and outdoor lighting) can be set. Four sets of CLCs are used to correspond to four types of lighting environments, and the bandpass filter covers the visible light + near-infrared (700~1000nm) thermal radiation band.

[0067] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0068] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A design method for a dual CLC cooperative filter switching device adapted to a wide viewing angle, characterized in that, The filter switching device includes a dual bandpass filter (1), a left-handed CLC filter (2), and a right-handed CLC filter (3) stacked sequentially. The left-handed CLC filter (2) and the right-handed CLC filter (3) are connected to a driving circuit via electrodes. The driving circuit controls the power supply to and from the left-handed CLC filter (2) and the right-handed CLC filter (3). The dual bandpass filter (1) allows band A and band B to pass through. The left-handed CLC filter (2) is configured to reflect left-handed circularly polarized light of band A when the power is off, and transmit band A. The right-hand circularly polarized light is reflected by the right-hand circularly polarized light of band A when the power is off, and the left-hand circularly polarized light of band A is transmitted. When the left-hand CLC plate (2) and the right-hand CLC plate (3) are powered on, both band A and band B are allowed to pass through. An infrared supplementary light is also provided in front of the filter switching device. The infrared supplementary light is connected to the driving circuit. When the driving circuit powers the left-hand CLC plate (2) and the right-hand CLC plate (3), it simultaneously powers the infrared supplementary light. Band A is the near-infrared band. The method includes the following steps: S1. Determine the infrared filler lamp model based on band A, extract the spectral function of the infrared filler lamp, and set the target center reflection wavelength range of the CLC sheet based on the relative radiation intensity. S2. Construct a cholesteric liquid crystal reflectance characteristic testing platform. For the CLC sheet placed on it, collect reflectance spectra corresponding to different target center reflection wavelengths. Based on a preset reflectance threshold, extract high reflectance bands and remove target center reflection wavelengths that do not cover band A to obtain the corrected range of target center reflection wavelengths for the CLC sheet. Simultaneously, a correlation function between the high reflectivity wavelength and the target center reflection wavelength is established. To obtain the permissible reflection wavelength range ; S3, according to the first preset step size, from the allowable reflection wavelength range Several reflection wavelengths to be fitted are selected, and the reflection wavelength shift of the CLC sheet at various viewing angles is tested for different reflection wavelengths to be fitted. The reflection wavelength shift is then fitted to obtain the result. With the reflected wavelength Perspective The coupling relationship function; S4, according to the second preset step size, the wavelength range of the reflection from the target center is selected. Select several reflection wavelengths to be tested The corresponding high reflectivity band is obtained. And the second left shift at the maximum and minimum viewing angles. and ; S5. For different target center reflection wavelengths, using the corresponding high reflectivity band as the maximum limiting range, and taking band A as the target filtering band, several models of dual bandpass filters are selected, and the effective filtering wavelength range of each dual bandpass filter model is obtained according to the preset transmittance threshold. The transmittance of the dual-bandpass filter within the effective filtering wavelength range was measured. and the central reflection wavelength is The reflectivity of CLC film And the first left shift of the dual bandpass filter at the maximum and minimum viewing angles. and , j represents the j-th filter film; S6. With the constraint that the product of the transmittance of each wavelength in band A at the minimum and maximum viewing angles of the CLC film and the dual bandpass filter in the power-off state is less than their respective minimum allowable transmittance thresholds, and with the optimization objectives of minimizing the relative left shift between the dual bandpass filter and the CLC film, minimizing the total transmittance of the CLC film and the dual bandpass filter in the power-off state within the effective filtering wavelength range, and maximizing the total light transmission efficiency of the CLC film and the dual bandpass filter in the power-on state within the effective filtering wavelength range, an optimization problem is constructed. The optimization problem is solved to select the optimal target center reflection wavelength of the CLC film and the optimal filter film model from the target center reflection wavelength range.

2. The design method of the dual CLC cooperative filter switching device adapted to a wide viewing angle according to claim 1, characterized in that, Band B is the visible light band.

3. The design method of the dual CLC cooperative filter switching device adapted to a wide viewing angle according to claim 1, characterized in that, In step S6, the optimization problem is: ； In the formula, and The center reflection wavelengths in the power-off state are respectively... The wavelength of CLC film at the minimum and maximum viewing angles The corresponding reflectivity, This indicates the maximum viewing angle of the filter switching device. and These represent the wavelengths of the selected j-th filter at the minimum and maximum viewing angles, respectively. Corresponding transmittance; and These represent the wavelengths at the minimum and maximum viewing angles, respectively. The corresponding weighting factor is affected by the photosensitivity of the photosensitive device to wavelength; This indicates the wavelength of a CLC sheet in its energized state at its minimum viewing angle. The corresponding transmittance, and These are the weighting factors for the minimum and maximum viewing angles, respectively, in transmission mode; This represents the light intensity curve of the infrared supplementary light. and These represent the minimum permissible transmittance thresholds when power is off and when power is on, respectively. and These are the maximum allowable relative offsets at the minimum and maximum viewing angles, respectively. It represents the minimum total transmittance at the smallest viewing angle under perspective conditions; and These are the minimum and maximum wavelengths of band A, respectively; The optimal target center reflection wavelength and the optimal filter film model for the CLC film are selected from the range of target center reflection wavelength values ​​by obtaining the optimization model.

4. The design method of the dual CLC cooperative filter switching device adapted to a wide viewing angle according to claim 1, characterized in that, The method further includes: The reflection wavelength of the CLC sheet at different voltages was tested, and the relationship function between voltage and target center reflection wavelength was obtained by fitting. The target center reflection wavelength was adjusted by adjusting the voltage.

5. The design method of the dual CLC cooperative filter switching device adapted to a wide viewing angle according to claim 1, characterized in that, The method further includes: By combining the scene light environment of the filter switching device, the target wavelength of different scene light environments is obtained, and the number of CLC sheet combinations and the reflection wavelength of different CLC sheets are set accordingly. Each CLC sheet combination corresponds to a working mode of a scene light environment. Select the appropriate bandpass filter according to the target band so that the effective filtering wavelength range of the bandpass filter covers all target bands; For different lighting environments, an optimization problem is constructed with the constraint that the transmittance of the CLC sheet combination and bandpass filter in the power-off state is less than the minimum allowable transmittance threshold for each wavelength in the target band at both the minimum and maximum viewing angles. The optimization objectives are to minimize the total transmittance of the CLC sheet combination and bandpass filter in the power-off state within the effective filter wavelength range and maximize the total light transmission efficiency of the CLC sheet combination and bandpass filter in the power-on state in the corresponding target band. The optimization problem is solved by selecting the optimal target center reflection wavelength and the optimal filter film model for each CLC sheet combination from the range of target center reflection wavelength values.

6. The design method of the dual CLC cooperative filter switching device adapted to a wide viewing angle according to claim 1, characterized in that, The scene lighting environment is set according to the ambient light intensity and is divided into night, dawn / dusk and day.

7. A smart camera for day and night surveillance, characterized in that, The application of the filter switching device as described in claim 1 includes a camera body, and the filter switching device is installed at the front end of the camera body.

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