Optical filter, camera module and electronic device

Abstract

Provided in the present application are an optical filter, a camera module and an electronic device. The optical filter comprises a substrate, an electrochromic thin film and a dual-bandpass thin film. The electrochromic thin film comprises an electrochromic material, which has a first refractive index under a first electrical signal such that a transmission band of the electrochromic thin film comprises a first visible light band, and has a second refractive index under a second electrical signal such that a transmission band of the electrochromic thin film comprises a first infrared light band, wherein the first refractive index is less than the second refractive index. A transmission band of the dual-bandpass thin film comprises a second visible light band and a second infrared light band, wherein the second visible light band at least partially overlaps with the first visible light band, the second infrared light band at least partially overlaps with the first infrared light band, and the second infrared light band does not overlap with the transmission band of the electrochromic thin film under the first electrical signal. The technical solution can improve the low-light unlocking performance without affecting normal photographing.

Description

Filters, camera modules and electronic devices

[0001] This application claims priority to Chinese Patent Application No. 202411516097.1, filed on October 28, 2024, entitled "Filter, Camera Module and Electronic Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of electronic device technology, and more specifically, to a filter, a camera module, and an electronic device. Background Technology

[0003] Currently, many electronic devices (such as smartphones, access control machines, and time attendance machines) have facial recognition capabilities. Facial recognition is a biometric technology that identifies individuals based on their facial features. During facial recognition, a camera typically captures images or video streams containing faces, automatically detects and tracks faces within the images, and then performs facial recognition on the detected faces.

[0004] Commonly used facial recognition methods primarily rely on imaging with visible light or actively emitted near-infrared light from the environment. Neither of these methods can simultaneously guarantee image capture performance and low-light unlocking performance. For example, in visible light-based facial recognition schemes, longer exposure times are required in low-light environments to obtain images that meet quality requirements, resulting in excessively long unlocking times. In near-infrared-based facial recognition schemes, the entry of near-infrared light during image capture (especially in bright light environments) poses a risk of false colors, affecting image quality.

[0005] Therefore, there is an urgent need to provide a solution that can improve low-light unlocking performance without affecting normal photo taking. Summary of the Invention

[0006] This application provides a filter, a camera module, and an electronic device that can improve low-light unlocking performance without affecting normal photo taking.

[0007] In a first aspect, a filter is provided, comprising a substrate, a field-chromic film, and a dual-pass film stacked together; the field-chromic film includes a field-chromic material, which has a first refractive index under the action of a first electrical signal, such that the transmission band of the field-chromic film includes a first visible light band, and the field-chromic material has a second refractive index under the action of a second electrical signal, such that the transmission band of the field-chromic film includes a first infrared light band, wherein the first refractive index is less than the second refractive index; the transmission band of the dual-pass film is a second visible light band and a second infrared light band, wherein the second visible light band at least partially overlaps with the first visible light band, the second infrared light band at least partially overlaps with the first infrared light band, and the second infrared light band does not overlap with the transmission band of the field-chromic film under the first electrical signal.

[0008] In this application, the filter operates at different wavelengths under different electrical signals. By switching the filter's operating wavelength, different functions can be achieved in various scenarios, thereby improving the user experience in different usage scenarios. For example, when taking a picture, the filter can block infrared light, thus avoiding the influence of infrared light on visible light imaging, reducing the risk of false colors, and improving the photography experience. When unlocking in low-light environments, the filter can allow infrared light to pass through, thereby shortening the unlocking time and improving unlocking performance. Furthermore, the refractive index of the field-chromic material used in the filter to allow infrared light to pass through is greater than the refractive index of the field-chromic material used when the filter blocks infrared light, which can avoid the risk of false colors at large angles.

[0009] In conjunction with the first aspect, in one possible implementation, the minimum wavelength value of the transmission band of the field-chromic film under the first electrical signal is less than or equal to the minimum wavelength value of the transmission band of the field-chromic film under the second electrical signal; and the maximum wavelength value of the transmission band of the field-chromic film under the first electrical signal is less than the maximum wavelength value of the transmission band of the field-chromic film under the second electrical signal.

[0010] Thus, when switching from the second electrical signal to the first electrical signal, the transmission band of the field-chromic film shifts towards the shortwave direction, which is beneficial to ensure that the transmission band of the field-chromic film under the first electrical signal includes the first visible light band and does not overlap with the second infrared light band.

[0011] In conjunction with the first aspect, in one possible implementation, the transmission band of the field-chromic film under the first electrical signal is obtained by shifting the transmission band of the field-chromic film under the second electrical signal towards a shorter wavelength.

[0012] Thus, even at large angles of incidence, the transmission band of the field-chromatic film under the first electrical signal will not overlap with the second infrared light band, thus avoiding the risk of false color at large angles.

[0013] In conjunction with the first aspect, in one possible implementation, the difference between the second refractive index and the first refractive index is greater than or equal to 0.1 and less than or equal to 4.

[0014] The greater the difference between the second refractive index and the first refractive index, the greater the passband shift of the field-chromic film. This allows the distance between the transmission band of the field-chromic film under the first electrical signal and the infrared transmission band of the double-pass film to be greater, thereby effectively achieving the cutoff effect of the filter on infrared light under the first electrical signal.

[0015] In conjunction with the first aspect, in one possible implementation, the field-chromic film's transmission band under the second electrical signal further includes a third visible light band, which at least partially overlaps with the second visible light band.

[0016] In this way, by switching different electrical signals, the filter can allow visible light to pass through in a fixed manner, and selectively allow infrared light to pass through.

[0017] In conjunction with the first aspect, in one possible implementation, the maximum wavelength of the third visible light band is less than or equal to the minimum wavelength of the first infrared light band.

[0018] The third visible light band and the first infrared light band can be two relatively independent bands, or they can form a continuous band.

[0019] In conjunction with the first aspect, in one possible implementation, the transmission band of the field-chromic film under the first electrical signal also includes a third infrared band, which does not overlap with the second infrared band.

[0020] In this way, when switching from the second electrical signal to the first electrical signal, the third infrared light band can be obtained by shifting the first infrared light band towards a shorter wavelength, which can reduce the design difficulty of the transmission band of the field-chromic film.

[0021] In conjunction with the first aspect, in one possible implementation, the field-chromic film includes at least three light-transmitting layers and at least one transparent conductive layer stacked together. Any two adjacent light-transmitting layers among the at least three light-transmitting layers have different refractive indices. The light-transmitting layer located between two light-transmitting layers among the at least three light-transmitting layers is an intermediate light-transmitting layer. The intermediate light-transmitting layer has two adjacent light-transmitting layers distributed on opposite sides. The refractive indices of the two adjacent light-transmitting layers are both greater than the refractive index of the intermediate light-transmitting layer, or the refractive indices of the two adjacent light-transmitting layers are both less than the refractive index of the intermediate light-transmitting layer. At least a portion of the at least three light-transmitting layers includes the field-chromic material.

[0022] By alternating layers of high-refractive-index and low-refractive-index light-transmitting materials, different orders of reflection peaks can be constructed, thereby adjusting the transmittance of the filter for different wavelengths of light. This allows the filter to achieve high transmittance across multiple wavelengths, thus improving the passband range. Changes in the refractive index of the field-chromatic material alter the transmittance curve of the filter, thereby enabling the switching of the filter's operating wavelength.

[0023] In conjunction with the first aspect, in one possible implementation, the refractive index of the light-transmitting layer farthest from the substrate among the at least three light-transmitting layers is greater than the refractive index of the light-transmitting layer adjacent to it; and / or the refractive index of the light-transmitting layer closest to the substrate among the at least three light-transmitting layers is greater than the refractive index of the light-transmitting layer adjacent to it.

[0024] The arrangement of the high-refractive-index light-transmitting layers in odd numbers and the low-refractive-index light-transmitting layers in even numbers facilitates switching between the transmission and reflection of light waves by the filter.

[0025] In conjunction with the first aspect, in one possible implementation, the field-chromic film includes one of the transparent conductive layers, and the field-chromic material is a thermochromic material; or the field-chromic film includes two of the transparent conductive layers, with the field-chromic material located between the two transparent conductive layers, and the field-chromic material is an electrochromic material.

[0026] In conjunction with the first aspect, in one possible implementation, when the field-chromic material is a thermochromic material, the field-chromic material includes at least one of the following: vanadium dioxide, antimony trisulfide, germanium-antimony-tellurium alloy, and antimony selenide; when the field-chromic material is an electrochromic material, the field-chromic material includes at least one of the following: nickel oxide, tungsten trioxide, vanadium pentoxide, and liquid crystal.

[0027] In conjunction with the first aspect, in one possible implementation, the field-chromatic thin film further includes an anti-reflective layer disposed on at least one side surface of the transparent conductive layer in the thickness direction.

[0028] An anti-reflective layer can increase the light transmittance of a transparent conductive layer by reducing its reflectivity, thereby achieving the purpose of enhancing light transmission.

[0029] In conjunction with the first aspect, in one possible implementation, the field-chromic film and the dual-pass film are disposed on opposite sides of the substrate in the thickness direction; or the field-chromic film and the dual-pass film are disposed on the same side of the substrate in the thickness direction.

[0030] In a second aspect, a camera module is provided, comprising: a lens, an image sensor, and a filter as described in the first aspect and any implementation thereof, wherein the lens is used to project an imaging beam from a subject onto the image sensor, and the filter is disposed in the optical path to filter the imaging beam.

[0031] In this application, the filter has different operating bands under different electrical signals. By switching the operating band of the filter, the camera module can achieve its functions in different scenarios, thereby improving the user experience in different usage scenarios.

[0032] In conjunction with the second aspect, in one possible implementation, the filter is disposed between the lens and the image sensor, or on the side of the lens away from the image sensor, or within the lens.

[0033] In conjunction with the second aspect, in one possible implementation, the camera module has a first operating mode and a second operating mode, wherein in the first operating mode, the filter is subjected to the first electrical signal, and in the second operating mode, the filter is subjected to the second electrical signal.

[0034] Under different electrical signals, the camera module has different working modes, thus enabling its application in different scenarios.

[0035] In conjunction with the second aspect, in one possible implementation, the first working mode is used for taking photos, and the second working mode is used for face unlocking; or, the first working mode is used for taking photos and face unlocking in bright light environments, and the second working mode is used for face unlocking in low light environments.

[0036] In the first approach, when a user wants to take a photo using the camera module, the filter blocks infrared light, preventing infrared light from entering and causing color distortion in the image, thus improving image quality. When the user wants to unlock the camera module, the filter allows infrared light to pass through, reducing unlocking time. Furthermore, the infrared reflectivity of skin enables more accurate facial recognition.

[0037] In the second approach, when unlocking in low-light conditions, the filter allows infrared light to pass through, shortening the unlocking time and improving performance. In other scenarios, the filter does not allow infrared light to pass through, preventing infrared light from affecting the quality of the captured image. Furthermore, in bright light conditions, visible light is used for unlocking, eliminating the need for the electronic device to actively emit infrared light and saving power.

[0038] In conjunction with the second aspect, in one possible implementation, the camera module further includes an infrared emitting module for emitting a fourth infrared light band that at least partially overlaps with the second infrared light band and at least partially overlaps with the first infrared light band.

[0039] Thirdly, a camera module is provided, comprising: a lens, an image sensor, a first filter, and a second filter. The lens projects an imaging beam from a subject onto the image sensor. The first filter and the second filter are disposed in an optical path to filter the imaging beam. The first filter includes a first substrate and a field-chromic film stacked together. The field-chromic film includes a field-chromic material, which has a first refractive index under the action of a first electrical signal, such that the transmission band of the field-chromic film includes a first visible light band. The material has a second refractive index under the action of the second electrical signal, so that the transmission band of the field-chromic film includes a first infrared light band, wherein the first refractive index is less than the second refractive index; the second filter includes a second substrate and a double-pass film stacked together, the transmission band of the double-pass film being a second visible light band and a second infrared light band, wherein the second visible light band at least partially overlaps with the first visible light band, the second infrared light band at least partially overlaps with the first infrared light band, and the second infrared light band does not overlap with the transmission band of the field-chromic film under the first electrical signal.

[0040] In conjunction with the third aspect, in one possible implementation, the minimum wavelength value of the transmission band of the field-chromic film under the first electrical signal is less than or equal to the minimum wavelength value of the transmission band of the field-chromic film under the second electrical signal; the maximum wavelength value of the transmission band of the field-chromic film under the first electrical signal is less than the maximum wavelength value of the transmission band of the field-chromic film under the second electrical signal.

[0041] In conjunction with the third aspect, in one possible implementation, the transmission band of the field-chromic film under the first electrical signal is obtained by shifting the transmission band of the field-chromic film under the second electrical signal towards a shorter wavelength.

[0042] In conjunction with the third aspect, in one possible implementation, the difference between the second refractive index and the first refractive index is greater than or equal to 0.1 and less than or equal to 4.

[0043] In conjunction with the third aspect, in one possible implementation, the field-chromic film's transmission band under the second electrical signal further includes a third visible light band, which at least partially overlaps with the second visible light band.

[0044] In conjunction with the third aspect, in one possible implementation, the maximum wavelength of the third visible light band is less than or equal to the minimum wavelength of the first infrared light band.

[0045] In conjunction with the third aspect, in one possible implementation, the transmission band of the field-chromic film under the first electrical signal also includes a third infrared band, which does not overlap with the second infrared band.

[0046] In conjunction with the third aspect, in one possible implementation, the field-chromic film includes at least three light-transmitting layers and at least one transparent conductive layer stacked together. Any two adjacent light-transmitting layers among the at least three light-transmitting layers have different refractive indices. The light-transmitting layer located between two light-transmitting layers among the at least three light-transmitting layers is an intermediate light-transmitting layer. The intermediate light-transmitting layer has two adjacent light-transmitting layers distributed on opposite sides. The refractive indices of the two adjacent light-transmitting layers are both greater than the refractive index of the intermediate light-transmitting layer, or the refractive indices of the two adjacent light-transmitting layers are both less than the refractive index of the intermediate light-transmitting layer. At least a portion of the at least three light-transmitting layers includes the field-chromic material.

[0047] In conjunction with the third aspect, in one possible implementation, the refractive index of the light-transmitting layer farthest from the substrate among the at least three light-transmitting layers is greater than the refractive index of its adjacent light-transmitting layer; and / or the refractive index of the light-transmitting layer closest to the substrate among the at least three light-transmitting layers is greater than the refractive index of its adjacent light-transmitting layer.

[0048] In conjunction with the third aspect, in one possible implementation, the field-chromic film includes one of the transparent conductive layers, and the field-chromic material is a thermochromic material; or the field-chromic film includes two of the transparent conductive layers, with the field-chromic material located between the two transparent conductive layers, and the field-chromic material is an electrochromic material.

[0049] In conjunction with the third aspect, in one possible implementation, when the field-chromic material is a thermochromic material, the field-chromic material includes at least one of the following: vanadium dioxide, antimony trisulfide, germanium-antimony-tellurium alloy, and antimony selenide; when the field-chromic material is an electrochromic material, the field-chromic material includes at least one of the following: nickel oxide, tungsten trioxide, vanadium pentoxide, and liquid crystal.

[0050] In conjunction with the third aspect, in one possible implementation, the field-chromic film further includes an anti-reflective layer disposed on at least one side surface of the transparent conductive layer in the thickness direction.

[0051] In conjunction with the third aspect, in one possible implementation, the first filter or the second filter is disposed between the lens and the image sensor, or disposed on the side of the lens away from the image sensor, or disposed within the lens.

[0052] In conjunction with the third aspect, in one possible implementation, the camera module has a first operating mode and a second operating mode, wherein in the first operating mode, the first filter is subjected to the first electrical signal, and in the second operating mode, the first filter is subjected to the second electrical signal.

[0053] In conjunction with the third aspect, in one possible implementation, the first working mode is used for taking photos, and the second working mode is used for face unlocking; or, the first working mode is used for taking photos and face unlocking in bright light environments, and the second working mode is used for face unlocking in low light environments.

[0054] In conjunction with the third aspect, in one possible implementation, the camera module further includes an infrared emitting module for emitting a fourth infrared light band that at least partially overlaps with the second infrared light band and at least partially overlaps with the first infrared light band.

[0055] Fourthly, a camera module is provided, comprising: a lens, an image sensor, and a filter. The lens projects an imaging beam from a subject onto the image sensor, and the filter is disposed in the optical path to filter the imaging beam. The filter is used to transmit visible light but not infrared light under a first electrical signal, and to transmit infrared light under a second electrical signal. The camera module has a first operating mode and a second operating mode, the first operating mode corresponding to the first electrical signal and the second operating mode corresponding to the second electrical signal. The first operating mode is used for taking a picture, and the second operating mode is used for face unlocking; or, the first operating mode is used for taking a picture and face unlocking in a bright light environment, and the second operating mode is used for face unlocking in a low light environment.

[0056] In conjunction with the fourth aspect, in one possible implementation, the filter is also used to transmit visible light under the second electrical signal.

[0057] In conjunction with the fourth aspect, in one possible implementation, the filter includes a substrate and a field-chromic film stacked together. The field-chromic film includes a field-chromic material, which has a first refractive index under the action of the first electrical signal, such that the transmission band of the field-chromic film includes the visible light band but excludes the infrared light band. The field-chromic material has a second refractive index under the action of the second electrical signal, such that the transmission band of the field-chromic film includes the infrared light band.

[0058] In conjunction with the fourth aspect, in one possible implementation, the filter includes a substrate, a field-chromic film, and a dual-pass film stacked together; the field-chromic film includes a field-chromic material, which has a first refractive index under the action of a first electrical signal, such that the transmission band of the field-chromic film includes a first visible light band, and the field-chromic material has a second refractive index under the action of a second electrical signal, such that the transmission band of the field-chromic film includes a first infrared light band, wherein the first refractive index is less than the second refractive index; the transmission band of the dual-pass film is a second visible light band and a second infrared light band, wherein the second visible light band at least partially overlaps with the first visible light band, the second infrared light band at least partially overlaps with the first infrared light band, and the second infrared light band does not overlap with the transmission band of the field-chromic film under the first electrical signal.

[0059] Fifthly, an electronic device is provided, including an image processor and a camera module according to the second to fourth aspects and any implementation thereof, wherein the image processor is communicatively connected to the camera module and is used to receive and process images acquired by the camera module.

[0060] The beneficial effects of the apparatus described in the third to fifth aspects above are the same as those described in the first and second aspects above, and will not be repeated here. Attached Figure Description

[0061] Figure 1 is a schematic structural diagram of an electronic device applicable to an embodiment of this application.

[0062] Figure 2 is a schematic exploded view of a camera module provided in an embodiment of this application.

[0063] Figure 3 is a schematic cross-sectional view of a camera module provided in an embodiment of this application.

[0064] Figure 4 is a schematic structural diagram of a filter provided in an embodiment of this application.

[0065] Figure 5 is a schematic structural diagram of a filter provided in an embodiment of this application.

[0066] Figure 6 is a schematic diagram of the refractive index variation of the switchable layer in the filter shown in Figure 5.

[0067] Figure 7 is a schematic structural diagram of a filter provided in an embodiment of this application.

[0068] Figure 8 is a schematic structural diagram of a filter provided in an embodiment of this application.

[0069] Figure 9 is a schematic structural diagram of a filter provided in an embodiment of this application.

[0070] Figure 10 is a schematic diagram of the refractive index variation of the switchable layer in the filter shown in Figure 9.

[0071] Figure 11 is a schematic structural diagram of a filter provided in an embodiment of this application.

[0072] Figure 12 is a schematic structural diagram of a filter provided in an embodiment of this application.

[0073] Figure 13 is a schematic structural diagram of a filter provided in an embodiment of this application.

[0074] Figure 14 is a schematic diagram of the transmittance curve of a filter provided in an embodiment of this application.

[0075] Figure 15 is a schematic diagram of the transmittance curve of another filter provided in an embodiment of this application.

[0076] Figure 16 is a schematic structural diagram of a filter provided in an embodiment of this application.

[0077] Figure 17 is a schematic structural diagram of a filter provided in an embodiment of this application.

[0078] Figure 18 is a schematic diagram of the transmittance curve of a filter provided in an embodiment of this application.

[0079] Figure 19 is a schematic diagram of the transmittance curves of a filter provided in an embodiment of this application under different modes.

[0080] Figure 20 is a schematic diagram of the transmittance curves of the field-dependent color-changing material when it changes from a low refractive index to a high refractive index, and the filter switches from infrared light mode to visible light mode.

[0081] Figure 21 is a schematic diagram of the transmittance curves when the field-dependent color-changing material changes from a high refractive index to a low refractive index, and the filter switches from infrared light mode to visible light mode.

[0082] Figure 22 is a schematic diagram of the transmittance curves when the field-dependent color-changing material changes from a high refractive index to a low refractive index, and the filter switches from infrared light mode to visible light mode.

[0083] Figure 23 is a schematic structural diagram of a filter assembly provided in an embodiment of this application.

[0084] Figure 24 is a schematic diagram of the ideal transmittance curves of a filter under different states provided in the embodiments of this application.

[0085] Figure 25 is a schematic diagram of a filter setting position provided in an embodiment of this application.

[0086] Figure 26 is a schematic diagram of another filter setting position provided in an embodiment of this application.

[0087] Figure 27 is a schematic diagram of another filter placement position provided in an embodiment of this application.

[0088] Figure 28 is a schematic diagram of another filter placement position provided in an embodiment of this application.

[0089] Figure 29 is a schematic structural diagram of a camera module provided in an embodiment of this application.

[0090] Figure 30 is a schematic diagram of the transmittance curve of a filter provided in an embodiment of this application.

[0091] Figure 31 is a schematic structural diagram of a camera module provided in an embodiment of this application. Detailed Implementation

[0092] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0093] It should be noted that, in the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in this article is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone.

[0094] In the embodiments of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more, and "at least one" and "one or more" refer to one, two, or more than two. The singular expressions "a," "an," "the," "the," "this," and "this" are intended to also include expressions such as "one or more," unless the context explicitly indicates otherwise.

[0095] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0096] In the description of the embodiments of this application, the terms "upper," "lower," "inner," "outer," "vertical," and "horizontal," etc., indicate orientations or positional relationships relative to the orientations or positions of the components shown in the accompanying drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and not to indicate or imply a specific orientation that the device or component must have, or that it must be constructed and operated in a specific orientation. They can change accordingly depending on the orientation of the components in the accompanying drawings, and therefore should not be construed as limiting this application. Furthermore, "vertical" in this application is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range. Additionally, in the embodiments of this application, descriptions such as "when," "in the case of," "if," and "if" all refer to the device taking corresponding actions under certain objective circumstances, not to limiting the time, nor to requiring the device to perform a judgment action during implementation, nor implying any other limitations.

[0097] In the embodiments of this application, the same reference numerals are used to denote the same component or part. Furthermore, the parts in the drawings are not drawn to scale, and the dimensions and sizes of the parts shown are merely exemplary and should not be construed as limiting the scope of this application.

[0098] To facilitate understanding, the technical terms used in this application will be explained and described below.

[0099] The optical axis is an imaginary line in an optical system, which can be understood as the direction in which light rays are transmitted through the optical system. Specifically, the optical axis can be considered as an axis perpendicular to the center of each lens in a lens. For a symmetrical transmission system, its optical axis generally coincides with the rotation center line of the optical system.

[0100] Optical thin films are thin films with special properties that can modulate the phase and amplitude of light through interference and diffraction, thereby achieving the refraction, reflection, and transmission of light waves. Optical thin films can be used in the fabrication of optical components such as mirrors, lenses, filters (e.g., optical filters), and beam splitters.

[0101] Electrochromic (EC) technology is a technology that allows materials to undergo stable and reversible color changes in their optical properties, such as reflectivity, refractive index, transmittance, and absorptivity, under the influence of an external electric field, thereby enabling active and dynamic control of light.

[0102] Wavelength range: refers to the continuous wavelength interval between one wavelength and another.

[0103] Admittance: The reciprocal of impedance (a complex number), symbolized by Y, and measured in Siemens (S). Admittance is a complex number; its real part is conductance, and its imaginary part is susceptance.

[0104] The figure of merit (FOM) is an important indicator for measuring a certain attribute or performance, generally used in scientific research, engineering design, and quality control. When applied to optical devices, the FOM specifically refers to the transmittance figure of merit. The transmittance figure of merit is a crucial parameter for measuring the transparency and optical performance of optical devices, commonly expressed as a percentage. Reference materials may include transparency curves, optical resonance peaks, and polarization characteristics. Transparency curves display transmittance at different wavelengths. Optical resonance peaks indicate a significant increase in transmittance at a specific wavelength. Polarization characteristics describe the device's response to light with different polarization directions.

[0105] The parameters of a filter include: center wavelength, transmittance, peak transmittance, bandwidth, cutoff band, and incident angle.

[0106] The center wavelength (CWL) is the midpoint between wavelengths where the peak transmittance is 50%, also known as the midpoint of the full width at half maximum (FWHM). Generally, the center wavelength represents the peak transmission wavelength of a bandpass or narrowband filter, or the peak reflection wavelength of a notch filter.

[0107] Transmittance refers to the ratio of light allowed to pass through a filter to incident light, usually expressed as a percentage. It generally represents the light loss that occurs after the light enters the filter. When the transmittance is 10% or below, it is considered a cutoff.

[0108] Peak transmittance refers to the highest transmittance value in the bandpass, that is, the highest value that can be transmitted after the filter has been damaged. In a spectral curve, the area through which light actually passes is usually called the passband.

[0109] Bandwidth (full width at half maximum, FWHM), also known as half-peak full width, is a wavelength range that represents the difference between the spectral bands where the peak transmittance is located. Filters with a half-width of less than 20 nm are called narrowband filters, while filters with a half-width greater than 20 nm are called bandpass filters.

[0110] The cut-off wavelength refers to the range of wavelengths that a filter can cut off.

[0111] The angle of incidence (AOI) is the angle between the incident light and the normal to the surface of the filter. When the light is incident perpendicularly, the angle of incidence is 0°.

[0112] It should be noted that the above-described terms and concepts are for illustrative purposes only and should not be construed as limiting the embodiments of this application.

[0113] Figure 1 shows a schematic structural diagram of an electronic device to which an embodiment of this application applies.

[0114] In this application, the electronic devices involved are those with imaging capabilities, such as mobile phones, personal digital assistants (PDAs), tablet computers, laptop computers, cameras, video recorders, smartwatches, smart wristbands, point-of-sale (POS) terminals, in-vehicle infotainment systems, televisions (e.g., smart screens), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, smart facial recognition access control machines, and facial recognition attendance machines. This application does not impose any special limitations on the specific form of the electronic devices. For ease of explanation and understanding, the following description uses a mobile phone as an example.

[0115] For example, Figures 1(a) and (b) schematically show the front and back of the electronic device 100, respectively. As shown in Figure 1, the electronic device 100 may include a housing 101, a display panel (DP) 102, and a camera compact module (CCM) 103.

[0116] The housing 101 has a receiving space for accommodating the components of the electronic device 100. The housing 101 also serves to protect the electronic device 100 and support the entire device. The display screen 102 and the camera module 103 are disposed within the receiving space of the housing 101 and connected to the housing 101. In some embodiments, the housing 101 may include a back cover opposite to the display screen 102 and a mid-frame disposed between the back cover and the display screen 102; the display screen 102 and the camera module 103 may be fixed to the mid-frame. The housing 101 may be made of metal, plastic, ceramic, or glass, etc.

[0117] The display screen 102 is used to display images, such as images captured by the camera module 103. The display screen 102 can be a liquid crystal display (LCD) screen, an organic light emitting diode (OLED) screen, etc. The display screen 102 can be a regular screen, or an irregularly shaped screen, a foldable screen, etc. The display screen 102 can be located on the front and / or back of the electronic device 100. Here, the front of the electronic device 100 can be understood as the side facing the user when using the electronic device 100, and the back of the electronic device 100 can be understood as the side facing away from the user when using the electronic device 100.

[0118] The camera module 103 is used to capture still images or videos. The camera module 103 can be disposed on the front and / or back of the electronic device 100. A front-mounted camera module 103 can also be referred to as a front-facing camera, and a rear-mounted camera module 103 can also be referred to as a rear-facing camera. During shooting, the user can select the appropriate camera module according to their shooting needs. In some embodiments, when the display screen 102 can be folded, the camera module 103 can function as either a front-facing or rear-facing camera as the display screen 102 folds. It is understood that the placement of the camera module 103 can be determined according to actual needs; the installation position shown in Figure 1 is merely illustrative.

[0119] It is understood that the placement of the camera module 103 can be determined according to actual needs, and the installation position shown in Figure 1 is merely illustrative. For example, when the camera module 103 is used as a front-facing camera, it can be placed at the top of the display screen 102 (e.g., near the earpiece); or, when the camera module 103 is used as a rear-facing camera, it can be placed at the upper left corner, upper right corner, or the middle of the upper half of the back of the electronic device 100; or, the camera module 103 can be placed on a component that is movable or rotatable relative to the display screen 102, so that the camera module 103 can retract or rotate relative to the main body of the electronic device 100.

[0120] In some embodiments, the camera module 103 can be a vertical module or a folding module (or periscope camera module). A vertical camera module can be understood as light entering the camera module directly hitting the image sensor without bending the light path. A folding camera module can be understood as light entering the camera module needing to pass through optical elements such as reflectors, lenses, and prisms before hitting the image sensor, resulting in a folded light path.

[0121] In some embodiments, the camera module 103 may be a telephoto module, a wide-angle module, an ultra-wide-angle module, or a depth-of-field module.

[0122] This application embodiment does not limit the number of camera modules 103; it can be one, two, four, or even more. When multiple camera modules 103 are set, these multiple camera modules 103 can be different, for example, they may have different lens optical parameters, different lens placement positions, different lens shapes, etc. This application embodiment does not limit the relative positions of the multiple camera modules; for example, the multiple camera modules can be arranged in a straight line or in a ring. In some embodiments, one or more of the multiple camera modules 103 can serve as the main camera module. Typically, the main camera module is responsible for the main shooting task, usually has the highest pixel count, and can provide higher resolution and a more powerful sensor, thereby meeting the user's photography needs in different scenarios.

[0123] In some embodiments, the electronic device 100 may further include a protective lens 104 for protecting the camera module 103. The protective lens 104 is disposed on the housing 101 and covers the camera module 103. In some embodiments, the protective lens 104 may also cover the display screen 102 of the electronic device 100 or the back of the electronic device 100.

[0124] In some embodiments, the protective lens 104 may be made of glass, sapphire, ceramic, etc., and this application does not impose any special limitations on it. For example, the protective lens 104 is transparent, and light from outside the electronic device 100 can enter the camera module 103 through the protective lens 104.

[0125] In some embodiments, the electronic device 100 may further include an image processor 105, which is located within the receiving space formed by the housing 101 and is communicatively connected to the camera module 103. The image processor 105 is used to acquire image data from the camera module 103 and process the image data. The communication connection between the image processor 105 and the camera module 103 may include data transmission via electrical connections such as wiring, or data transmission via coupling or other methods. It is understood that the image processor 105 and the camera module 103 may also be connected via other methods capable of data transmission.

[0126] The image processor 105 optimizes the digital image signal and transmits the processed signal to the display screen 102. The image processor 105 can be an image processing chip or a digital signal processing chip. Its function is to transmit the data obtained by the photosensitive chip to the central processing unit in a timely and fast manner and refresh the photosensitive chip. Therefore, the quality of the image processor 105 directly affects the image quality (such as color saturation, sharpness, etc.).

[0127] In some embodiments, the electronic device 100 may further include a circuit board located in the receiving space formed by the housing 101, and the image processor 105 is fixed to the circuit board and electrically connected to the circuit board.

[0128] In some embodiments, the electronic device 100 may further include an analog-to-digital converter (also called an A / D converter, not shown in the figure). The analog-to-digital converter is connected between the camera module 103 and the image processor 105. The analog-to-digital converter is used to convert the signal generated by the camera module 103 into a digital signal and transmit it to the image processor 105. After being processed by the image processor 105, the digital image signal can be transmitted to the display module, and finally displayed as an image or video on the display screen 102.

[0129] In some embodiments, the electronic device 100 may further include a memory (not shown) communicatively connected to the image processor 105. The image processor 105 processes the digital image signal before transmitting the image to the memory, so that the image can be retrieved from the memory and displayed on the display screen 102 at any time when it is needed to view the image later. In some embodiments, the image processor 105 may also compress the processed digital image signal before storing it in the memory to save memory space.

[0130] It should be understood that the structure shown in Figure 1 does not constitute a specific limitation on the electronic device 100. The electronic device 100 may include more or fewer components than shown in the figure. For example, the electronic device 100 may also include one or more of the following components: battery, flash, earpiece, buttons, sensors, etc., or the electronic device 100 may not include the display screen 102, or the electronic device 100 may also have a different component arrangement than shown in the figure.

[0131] Figures 2 and 3 show schematic diagrams of a camera module according to an embodiment of this application. Figure 2 is a schematic exploded view of the camera module 200, and Figure 3 is a schematic cross-sectional view of the camera module 200. The camera module 200 in Figure 2 can be an exemplary structure of the camera module 103 in Figure 1. The structure of the camera module 200 will be briefly described below with reference to Figures 2 and 3.

[0132] For ease of description, the optical axis direction of the camera module 200 is defined as the Z direction, and the two directions perpendicular to the optical axis are the X direction and the Y direction, with the X direction perpendicular to the Y direction. In this embodiment, the optical axis direction is the direction in which the optical system transmits light. The side closer to the object being photographed along the optical axis direction is the front side, and the side closer to the image of the object is the rear side.

[0133] Here, the definitions of the X, Y, and Z directions also apply to the various figures described below. It should be noted that the above definitions of the X, Y, and Z directions are merely for the convenience of describing the positional, connection, or motion relationships between the components in the embodiments of this application, and should not be construed as limiting the embodiments of this application.

[0134] As shown in Figures 2 and 3, the camera module 200 may include a housing 210, a lens assembly 220, a lens actuator 230, and a photosensitive assembly 240.

[0135] The housing 210 has a receiving space for accommodating the lens assembly 220, lens actuator 230, photosensitive assembly 240, etc. Additionally, the housing 210 also serves a protective and support function. It is understood that the structure of the housing 210 shown in Figures 2 and 3 is merely exemplary and does not constitute any limitation on this application. Those skilled in the art can design the shape of the housing 210 according to actual needs.

[0136] The lens assembly 220 mainly includes a lens group 221 and a lens barrel 222, wherein the lens group 221 is housed within the receiving space formed by the lens barrel 222. The lens assembly 220 is used to image the scene on the object side onto the image plane on the image side. In some embodiments, the lens assembly 220 can also perform certain processing on the received imaging beam, such as aberration correction and chromatic aberration elimination. Here, the imaging beam refers to the beam formed by the light incident on the camera module 200.

[0137] Lens group 221 may include at least one lens. The at least one lens may be different or at least partially the same. This application embodiment does not specifically limit the number of lenses included in lens group 221. Those skilled in the art can set the number of lenses according to actual needs, such as 1, 2, 3, 5, 8 or more.

[0138] The focal length of lens group 221 can be fixed, and correspondingly, lens assembly 220 is a prime lens. Alternatively, the focal length of lens group 221 can be adjusted, and correspondingly, lens assembly 220 is a zoom lens. For example, the focal length of lens group 221 can be adjusted by changing the relative positions of the lenses within it.

[0139] The lens barrel 222 has a receiving space, primarily for accommodating the lens assembly 221. In some embodiments, the lens barrel 222 can be a single unit, with the lens assembly 221 housed within this single unit. In other embodiments, the lens barrel 222 may also comprise multiple lens barrel sections, with the lens groups of the lens assembly 221 disposed within these multiple lens barrel sections. Exemplarily, the relative positions between these multiple lens barrel sections can be adjusted, enabling optical zoom by adjusting the relative positions of the lenses.

[0140] It is understood that the structure of the lens barrel 222 and the connection method between the lens group 221 and the lens barrel 222 in Figures 2 and 3 are merely exemplary and do not limit the embodiments of this application.

[0141] The lens actuator 230 is used to move the lens assembly 220 to achieve autofocus and / or optical image stabilization. In some embodiments, the lens actuator 230 may also be referred to as a lens motor, or simply a motor.

[0142] As shown in Figure 3, the lens assembly actuator 230 may include a motor (hereinafter referred to as the AF motor) 231 for moving the lens assembly 220 for AF and / or a motor (hereinafter referred to as the OIS motor) 232 for moving the lens assembly 220 for OIS. Specifically, the AF motor 231 is used to move the lens assembly 220 for autofocus in the Z direction, and the OIS motor 232 is used to move the lens assembly 220 for optical image stabilization in the X and / or Y directions.

[0143] In some embodiments, the AF motor 231 and the OIS motor 232 can be two independent components, each independently driving the lens assembly 220 for AF and OIS respectively. Alternatively, the AF motor 231 and the OIS motor 232 can be integrated into one unit, with a single motor driving the lens assembly 220 for AF and OIS. Figure 3 exemplarily illustrates that the lens actuator 230 includes independent AF motor 231 and OIS motor 232, but it should be understood that the embodiments of this application are not limited thereto.

[0144] In some embodiments, the AF motor 231 or the OIS motor 232 can be used to move the entire lens assembly 220, or to move a portion of the lens assembly 220. For example, if one part of the lens assembly 220 is relatively fixed and another part is movable, the AF motor 231 or the OIS motor 232 can drive the movable part to move, thereby changing the optical path to achieve the desired function.

[0145] In some embodiments, the AF motor 231 or the OIS motor 232 may be a voice coil motor (VCM), a shape memory alloy (SMA) motor, a stepping motor, a piezoelectric motor, etc. It should be understood that the specific structure of the AF motor 231 or the OIS motor 232 may be designed and selected according to the selected driving method, and the embodiments of this application do not limit this.

[0146] The photosensitive component 240 is primarily used for imaging. For example, the photosensitive component 240 may include a filter 241, an image sensor 242, and a circuit board 243.

[0147] The filter 241 is disposed in the optical path, for example, between the lens assembly 220 and the image sensor 242. The filter 241 can eliminate unwanted light projected onto the image sensor 242, preventing problems such as ghosting, stray light, and color cast from occurring during image formation.

[0148] Image sensor 242 is a semiconductor chip used to convert collected external light signals into electrical signals. Specifically, the surface of image sensor 242 contains hundreds of thousands to millions of photodiodes. These photodiodes generate charges when illuminated, thereby converting the light signals collected by lens assembly 220 into electrical signals. For example, image sensor 242 may be a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) device.

[0149] Circuit board 243 is used to transmit electrical signals, and it can be a flexible printed circuit (FPC) or a printed circuit board (PCB). Image sensor 242 can be electrically connected to circuit board 243 via wires to extract signals.

[0150] In some embodiments, the photosensitive component 240 may further include a microelectromechanical system (MEMS) actuator 244, which drives the image sensor 242 to move along the optical axis and / or perpendicular to the optical axis, thereby achieving autofocus and / or optical image stabilization. The MEMS actuator 244 can be driven by electrostatic force, magnetoelectric force, piezoelectric force, thermoelectric force, etc. It should be understood that the specific structure of the MEMS actuator 244 can be designed and selected according to the chosen driving method, and this application does not limit it in this regard.

[0151] It should be understood that the structures illustrated in Figures 2 and 3 do not constitute a specific limitation on the camera module 200. The camera module 200 may include more or fewer components than illustrated. For example, the camera module 200 may also include connectors and peripheral electronic components, or the camera module 200 may not include the lens actuator 230, which will not be described in detail here.

[0152] Currently, many electronic devices (such as smartphones, access control machines, and time attendance machines) have facial recognition capabilities. Facial recognition is a biometric technology that identifies individuals based on their facial features. During facial recognition, a camera typically captures images or video streams containing faces, automatically detects and tracks faces within the images, and then performs facial recognition on the detected faces.

[0153] Commonly used face recognition methods mainly include face recognition based on single-channel visible light imaging and face recognition based on active near-infrared imaging. Face recognition based on single-channel visible light imaging relies on visible light in the environment, therefore requiring longer exposure times in low-light environments to obtain images that meet quality requirements, resulting in excessively long face unlock times in low-light conditions. Face recognition based on active near-infrared imaging relies on active infrared emission, which can increase exposure and shorten exposure time, but requires a separate camera module for near-infrared imaging on the electronic device, increasing the number of openings and affecting the screen appearance.

[0154] In recent years, face recognition based on dual-pass filters has been proposed. Dual-pass filters have both visible and infrared light transmission properties. Visible light passing through the dual-pass filter can be used for normal photography, while near-infrared light can be used for face recognition. This solution eliminates the need for a separate camera module for near-infrared imaging, and can improve low-light unlocking performance by utilizing active infrared emission while maintaining screen aesthetics. However, this solution has the following intractable drawbacks:

[0155] 1) If the near-infrared light transmittance of the dual-pass filter is increased, there will be a risk of false color (i.e. color cast, such as the image color being reddish) when near-infrared light enters the environment under strong light, which will affect normal photography.

[0156] 2) If the near-infrared transmittance of the dual-pass filter is reduced, the signal-to-noise ratio of the near-infrared image used for face recognition will be low, and the unlocking time will be difficult to reduce significantly.

[0157] Therefore, face recognition schemes based on dual-pass filters cannot simultaneously avoid the risks of false colors and the problem of low signal-to-noise ratio in near-infrared images.

[0158] Therefore, embodiments of this application provide a filter and a camera module including the filter, which can improve low-light unlocking performance without affecting normal photography.

[0159] Figure 4 shows a schematic structural diagram of a filter provided in an embodiment of this application. The filter 300 shown in Figure 4 can be applied to the camera module 200 shown in Figure 2 or Figure 3. For example, the filter 300 can be a specific example of the filter 241 in Figure 3.

[0160] As shown in Figure 4, the filter 300 may include a substrate 310 and a field-chromic film 320 disposed on the substrate 310. Specifically, the field-chromic film 320 is disposed (or formed) on one surface of the substrate 310 in the thickness direction. In this embodiment, the areas of the two surfaces of the substrate 310 in the thickness direction are much larger than the areas of the other surfaces.

[0161] The substrate 310 can provide a forming surface for the field-chromic film 320. The substrate 310 is a transparent material, such as polyethylene terephthalate (PET), polycarbonate (PC), polymethyl methacrylate (PMMA), cycloolefin polymer (COP), or glass (such as white glass or blue glass).

[0162] In some embodiments, the substrate 310 can be a rigid substrate, such as made of materials like PC, PMMA, or glass. The rigid substrate can provide sufficient support to form a rigid film filter with the field-chromic film 320.

[0163] In other embodiments, the substrate 310 can be a flexible substrate, such as one made of PET or COP. The flexible substrate can adapt to planar and curved shapes and can form a soft film filter with the field-chromic film 320.

[0164] An electrical signal is applied to the field-chromic film 320. When the magnitude of the electrical signal is adjusted, the refractive index of the field-chromic film 320 changes, and correspondingly, the transmission band (or operating band) of the filter 300 changes. For example, when a first electrical signal is applied, the filter 300 is in visible light mode, and its operating band includes the visible light band. When a second electrical signal is applied, the filter 300 is in infrared light mode, and its operating band includes the infrared light band. In other words, by adjusting the electrical signal applied to the field-chromic film 320, the operating band of the filter 300 can be switched.

[0165] In this embodiment, the filter 300 is a light switching device. In visible light mode, the filter 300 can transmit visible light, and in infrared light mode, the filter 300 can transmit infrared light. Thus, in practical applications, the operating band of the filter 300 can be switched according to the usage scenario, improving the user experience in different usage scenarios.

[0166] For example, when taking a photo, the filter 300 can be set to visible light mode. Since infrared light is blocked, the influence of infrared light on visible light imaging can be avoided, reducing the risk of false colors and improving the photography experience.

[0167] For example, during face recognition, the filter 300 can be set to infrared light mode. Since infrared light can pass through the filter, face recognition can be performed in low-light environments using infrared light, which can shorten the unlocking time and improve unlocking performance.

[0168] In addition, the filter 300 has different operating bands in different modes. Therefore, by switching the operating band of a single filter, functions in different scenarios can be achieved without setting up multiple filters or multiple camera modules, which can save the space and cost occupied by the modules.

[0169] In some embodiments, the duration of the first electrical signal is the same as the duration for which the filter 300 maintains the visible light mode, and the duration of the second electrical signal is the same as the duration for which the filter 300 maintains the infrared light mode. This can be understood as follows: to maintain the filter 300 in the visible light mode, the first electrical signal must be continuously applied; to maintain the filter 300 in the infrared light mode, the second electrical signal must be continuously applied. This method ensures the stability of the filter 300 in either the visible light or infrared light mode.

[0170] In other embodiments, the duration of the first electrical signal is shorter than the time the filter 300 maintains the visible light mode, and the duration of the second electrical signal is shorter than the time the filter 300 maintains the infrared light mode. This can be understood as follows: when the first electrical signal is applied, the filter 300 switches to and maintains the visible light mode; if the first electrical signal is disconnected, the filter 300 still maintains the visible light mode. When the second electrical signal is applied, the filter 300 switches to and maintains the infrared light mode; if the second electrical signal is disconnected, the filter 300 still maintains the infrared light mode. This method can save power consumption.

[0171] In some embodiments, the thickness of the field-chromatic film 320 is less than or equal to 10 micrometers (μm) and less than or equal to 100 micrometers. Thus, the thickness of the field-chromatic film 320 has a negligible effect on the total track length (TTL).

[0172] In some embodiments, referring to FIG5, the field-chromic film 320 includes at least one high-refractive-index layer 321, at least one low-refractive-index layer 322, and at least one transparent conductive layer 323. The at least one high-refractive-index layer 321, the at least one low-refractive-index layer 322, and the at least one transparent conductive layer 323 are stacked, wherein the at least one high-refractive-index layer 321 and the at least one low-refractive-index layer 322 are arranged alternately, and the refractive index of the high-refractive-index layer 321 is greater than the refractive index of the low-refractive-index layer 322. One or more of the at least one high-refractive-index layer 321 and / or one or more of the at least one low-refractive-index layer 322 include a field-chromic material, wherein the refractive index of the field-chromic material is variable. For ease of description, this application refers to the high-refractive-index layer or low-refractive-index layer containing the field-chromic material as a switchable layer 324, and the refractive index of the switchable layer 324 is variable.

[0173] By alternating layers of high and low refractive indices, different orders of reflection peaks can be constructed, thereby adjusting the transmittance of the filter 300 for different wavelengths of light. This enables the filter 300 to achieve high transmittance across multiple wavelengths, improving the passband range. The transparent conductive layer 323 can apply an electrical signal (e.g., voltage or current) to the switchable layer 324. Under the influence of the electrical signal, the refractive index of the switchable layer 324 changes, which in turn alters the transmittance of a specific wavelength band through the filter 300, thus changing the operating wavelength of the filter 300. In this embodiment, the change in the refractive index of the switchable layer 324 alters the transmittance of the infrared band through the filter 300. By switching the operating wavelength of the filter 300, the purpose of switching the filter 300 on and off for infrared light is achieved.

[0174] For example, the field-chromic film 320 includes at least three light-transmitting layers and at least one transparent conductive layer stacked together, wherein any two adjacent light-transmitting layers have different refractive indices. The light-transmitting layer located between two light-transmitting layers is an intermediate light-transmitting layer, and each intermediate light-transmitting layer has two adjacent light-transmitting layers distributed on opposite sides. The refractive indices of the two adjacent light-transmitting layers are both greater than the refractive index of the intermediate light-transmitting layer, or the refractive indices of the two adjacent light-transmitting layers are both less than the refractive index of the intermediate light-transmitting layer; wherein at least a portion of the at least three light-transmitting layers comprises a field-chromic material.

[0175] It can be understood that if the refractive indices of two adjacent light-transmitting layers are both greater than the refractive index of the intermediate light-transmitting layer located between the two adjacent light-transmitting layers, then the intermediate light-transmitting layer is a low-refractive-index layer 322, and the two adjacent light-transmitting layers are two high-refractive-index layers 321. If the refractive indices of two adjacent light-transmitting layers are both less than the refractive index of the intermediate light-transmitting layer located between the two adjacent light-transmitting layers, then the intermediate light-transmitting layer is a high-refractive-index layer 321, and the two adjacent light-transmitting layers are two low-refractive-index layers 322.

[0176] In some embodiments, the refractive index of the light-transmitting layer farthest from the substrate 310 among the at least three light-transmitting layers is greater than the refractive index of the light-transmitting layer adjacent to it; and / or the refractive index of the light-transmitting layer closest to the substrate 310 among the at least three light-transmitting layers is greater than the refractive index of the light-transmitting layer adjacent to it.

[0177] That is, the light-transmitting layer farthest from the substrate 310 among the at least three light-transmitting layers is a high refractive index layer 321, and / or the light-transmitting layer closest to the substrate 310 among the at least three light-transmitting layers is a high refractive index layer 321.

[0178] For ease of understanding, the following descriptions of the solution provided in this application will use "high refractive index layer" and "low refractive index layer" to illustrate the solution. However, it is understood that the "high refractive index layer" and "low refractive index layer" mentioned in this application are specific examples of the aforementioned "transparent layer".

[0179] For example, the field-chromatic thin film 320 includes a plurality of high refractive index layers 321, a plurality of low refractive index layers 322 and at least one transparent conductive layer 323 stacked together, wherein the plurality of high refractive index layers 321 and the plurality of low refractive index layers 322 are stacked alternately, and the plurality of high refractive index layers 321 and / or the plurality of low refractive index layers 322 include one or more switchable layers 324.

[0180] For ease of description and distinction, the high refractive index layers in high refractive index layer 321, excluding the film layer containing the switchable material, will be referred to as conventional high refractive index layers, and the low refractive index layers in low refractive index layer 322, excluding the film layer containing the switchable material, will be referred to as conventional low refractive index layers. Both conventional high refractive index layers and conventional low refractive index layers are non-switchable layers, and the refractive index of non-switchable layers remains unchanged.

[0181] In some embodiments, in a local film system composed of the at least one high refractive index layer 321 and the at least one low refractive index layer 322, each high refractive index layer 321 is located in an odd-numbered layer of the local film system counting from the side closest to the substrate 310, and each low refractive index layer 322 is located in an even-numbered layer of the local film system counting from the side closest to the substrate 310, and / or, each high refractive index layer 321 is located in an odd-numbered layer of the local film system counting from the side furthest from the substrate 310, and each low refractive index layer 322 is located in an even-numbered layer of the local film system counting from the side furthest from the substrate 310.

[0182] That is, the distance between the high refractive index layer farthest from the substrate 310 in the at least one high refractive index layer 321 and the substrate 310 is greater than the distance between any one of the low refractive index layers 322 and the substrate 310, and / or the distance between the high refractive index layer closest to the substrate 310 in the at least one high refractive index layer 321 and the substrate 310 is less than the distance between any one of the low refractive index layers 322 and the substrate 310.

[0183] The arrangement of high refractive index layer 321 as an odd number of layers and low refractive index layer 322 as an even number of layers facilitates switching between the transmission and reflection of light waves by the filter. For example, the alternating arrangement of high and low refractive index layers facilitates the switching between reflecting infrared light in visible light mode and transmitting infrared light in infrared light mode.

[0184] In some embodiments, the transparent conductive layer 323 can be made of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), graphene, or a metal mesh material (such as conductive silver nanowires). Among these, ITO and FTO materials possess high conductivity, high visible light transmittance, high mechanical hardness, and good chemical stability.

[0185] In this embodiment, if the field-chromic film 320 includes multiple transparent conductive layers 323, the materials of the different transparent conductive layers 323 can be the same or different, depending on actual needs, and are not specifically limited here.

[0186] In some embodiments, the deposition methods of the transparent conductive layer 323 include, but are not limited to, electron beam evaporation, atomic layer deposition (e.g., chemical vapor deposition, physical vapor deposition, electron beam epitaxy), magnetron sputtering, solution printing, etc. In practical applications, a suitable deposition method can be selected based on the material of the transparent conductive layer 323. For example, magnetron sputtering can be used to deposit oxides such as ITO and FTO; solution methods or spray methods can be used to deposit conductive silver nanowires; chemical vapor deposition (CVD) can be used to deposit graphene, and so on.

[0187] In some embodiments, the thickness of the transparent conductive layer 323 is greater than or equal to 5 nanometers (nm) and less than or equal to 200 nanometers.

[0188] In some embodiments, the field-chromic film 320 may further include an anti-refletance (AR) coating (or AR film) stacked with the transparent conductive layer 323, wherein the AR coating is disposed on at least one surface of the transparent conductive layer 323 in the thickness direction. The AR coating can increase the light transmittance of the transparent conductive layer 323 by reducing its reflectivity, thereby achieving the purpose of enhancing light transmittance. For example, the overall transmittance of the AR coating and the transparent conductive layer 323 can reach more than 90% when combined.

[0189] For example, the AR coating can be deposited on at least one side surface of the transparent conductive layer 323 in the thickness direction. The AR coating can be a single-layer coating or a multi-layer coating.

[0190] In some embodiments, the deposition methods for AR coatings include, but are not limited to, electron beam evaporation, atomic layer deposition, and magnetron sputtering. In practical applications, a suitable deposition method can be selected based on the material of the AR coating.

[0191] As an example and not a limitation, if the transparent conductive layer 323 is an ITO film, then the transparent conductive layer 323 and the AR coating can form an AR-ITO film system.

[0192] In some embodiments, the low-refractive-index layer 322 has a low refractive index. For example, the refractive index of the low-refractive-index layer 322 is less than 1.7. Further, the refractive index of the low-refractive-index layer 322 is greater than or equal to 1.3.

[0193] In some embodiments, the material of the conventional low refractive index layer 322 includes, but is not limited to, silicon dioxide (SiO2), magnesium fluoride (MgF2), calcium fluoride (CaF2), etc. In practical applications, the material of the conventional low refractive index layer 322 can be selected as needed, and this application does not impose any special limitations on it. For example, the conventional low refractive index layer 322 may include one or more materials.

[0194] In this embodiment of the application, if the field-chromic film 320 includes multiple conventional low-refractive-index layers 322, the materials and refractive indices of the different conventional low-refractive-index layers 322 can be the same or different, depending on actual needs, and no special limitation is made here.

[0195] In some embodiments, the high refractive index layer 321 has a high refractive index. For example, the refractive index of the high refractive index layer 321 is greater than 1.7.

[0196] In this embodiment of the application, a film layer with a refractive index of 1.7 can be classified as a high refractive index layer or a low refractive index layer according to actual needs. For example, if the refractive index of the high refractive index layer 321 is greater than or equal to 1.7, then the refractive index of the low refractive index layer 322 is less than 1.7. Alternatively, if the refractive index of the high refractive index layer 321 is greater than 1.7, then the refractive index of the low refractive index layer 322 is less than or equal to 1.7.

[0197] In some embodiments, the material of the conventional high refractive index layer 321 includes, but is not limited to, titanium dioxide (TiO2), titanium pentoxide (Ti3O5), zirconium dioxide (ZrO2), tantalum pentoxide (Ta2O5), etc. In practical applications, the material of the conventional high refractive index layer can be selected as needed, and this application does not impose any special limitations on it. For example, the conventional high refractive index layer 321 may include one or more materials.

[0198] In this embodiment, if the field-chromic film 320 includes multiple conventional high refractive index layers 321, the materials and refractive indices of the different conventional high refractive index layers 321 can be the same or different, depending on actual needs, and no special limitation is made here.

[0199] In this embodiment, the switchable layer 324 includes a field-chromatic material. Field-chromatic materials are a class of substances that can undergo stable and reversible optical changes under the influence of external fields (such as electricity, heat, light, gas, etc.), and often manifest as reversible color changes in appearance.

[0200] In some embodiments, the switchable layer 324 includes a thermochromic material or an electrochromic material.

[0201] Thermochromic materials are functional materials whose absorption spectrum changes during heating and cooling, exhibiting characteristics where transmittance or color changes with temperature. For example, the material of the switchable layer 324 can be an inorganic or organic thermochromic material.

[0202] Inorganic thermochromic materials can include vanadium dioxide (VO2), sulfide phase change materials (such as antimony trisulfide (Sb2S3), GST, antimony selenide (Sb2Se3), perovskites, etc.), among which GST material is an alloy composed of germanium (Ge), antimony (Sb), and tellurium (Te), with the chemical formula Ge2Sb2Te5. It can switch between crystalline and amorphous states under the triggering of temperature, voltage, or laser pulses.

[0203] Organic thermochromic materials are usually polymers composed of aromatic molecules, macrocyclic aromatic molecules, and heterocyclic aromatic molecules, such as fluoranes, triarylmethanes, spiropyrans, and Schiff bases.

[0204] In some embodiments, the heat required for the color-changing process of the switchable layer 324 can be provided by the transparent conductive layer 323. For example, the transparent conductive layer 323 has a resistor, in which electrical energy can be converted into heat energy when current is passed through it.

[0205] Electrochromic materials are functional materials whose optical properties change stably and reversibly under the influence of electric current or electric field, manifesting as reversible color changes in appearance. For example, the material of the switchable layer 324 can be an inorganic electrochromic material, an organic electrochromic material, or a liquid crystal.

[0206] Inorganic electrochromic materials mainly include oxides of transition metals and their derivatives, such as nickel oxide (NiO), tungsten trioxide (WO3), molybdenum trioxide (MoO3), titanium dioxide (TiO2), iridium dioxide (IrO2), cobalt tetroxide (Co3O4), and vanadium pentoxide (V2O5). In addition, inorganic electrochromic materials also include other materials such as Prussian blue, tungsten sulfide, and nitrides of some metals.

[0207] Organic electrochromic materials mainly include polythiophene, polyaniline, polypyrrole, violetin, triphenylamine, tetrathiafulvalene, and metal phthalocyanine compounds.

[0208] Liquid crystals are a special state of matter, existing between crystals and liquids, exhibiting fluidity and some crystalline properties. Liquid crystal molecules maintain an ordered arrangement within a specific temperature range, displaying anisotropic optical and electrical properties. Liquid crystals are highly sensitive to electric fields, producing significant optical effects.

[0209] It is understood that the above classification of various field-induced color-changing materials is merely exemplary. In some embodiments, there may be overlap between thermochromic and electrochromic materials. For example, a material that can change its refractive index under the triggering of temperature or an electric field (such as current or voltage) is both an electrochromic and a thermochromic material.

[0210] In this embodiment, if the field-chromic film 320 includes multiple switchable layers 324, the materials of the different switchable layers 324 can be the same or different, depending on actual needs. For example, the different switchable layers 324 can be different thermochromic materials or different electrochromic materials.

[0211] In some embodiments, the refractive index of the switchable layer 324 ranges from 1.45 to 7. For example, the refractive index of the switchable layer 324 in a low refractive index state ranges from 1.45 to 4, and the refractive index in a high refractive index state ranges from 1.55 to 7. It is understood that because the switchable layer 324 has a wide refractive index range, several possible scenarios exist when different electrical signals are applied to the switchable layer 324.

[0212] In case 1, the refractive index of the switchable layer 324 is high under the action of the first and second electrical signals, for example, both are greater than 1.7. In this case, the switchable layer 324 is used as an example of the high refractive index layer 321 in both visible light mode and infrared light mode.

[0213] Case 2: When the refractive index of the switchable layer 324 is low under the action of the first and second electrical signals, for example, both are less than 1.7, the switchable layer 324 serves as an example of the low refractive index layer 322 in both visible light mode and infrared light mode.

[0214] Case 3: Under the action of the first and second electrical signals, the refractive index of the switchable layer 324 changes by a large range. In one mode, the switchable layer 324 can be used as an example of a high refractive index layer 321, and in another mode, it can be used as an example of a low refractive index layer 322.

[0215] In some embodiments, the thickness of the switchable layer 324 (referring to the thickness of a single layer) ranges from 5 nm to 100 μm. For example, the specific thickness range of the switchable layer 324 may vary depending on the field-chromic material. For instance, for liquid crystal materials, the corresponding thickness range of the switchable layer is approximately 5 μm to 100 μm. For example, for materials such as vanadium oxide and sulfides, the corresponding thickness range of the switchable layer is approximately 5 nm to 500 nm.

[0216] In some embodiments, the deposition method of the conventional high refractive index layer 321, the conventional low refractive index layer 322, or the switchable layer 324 may include, but is not limited to, electron beam evaporation, atomic layer deposition, magnetron sputtering, laser pulse deposition, etc. In practical applications, a suitable deposition method can be selected according to the material of the film.

[0217] In this embodiment, a change in the refractive index of the switchable layer 324 will cause a change in the color of the switchable layer 324, which in turn changes the spectral transmittance of the switchable layer 324.

[0218] In some embodiments, the refractive index of the switchable layer 324 can be changed based on chemical reactions, phase changes, or changes in the morphology of the liquid crystal structure.

[0219] For example, in a color-changing method based on a chemical reaction, the transparent conductive layer 323 applies an electrical signal (such as current) to the switchable layer 324, controlling the material of the switchable layer 324 to undergo a chemical reaction (such as a redox reaction), thereby causing a change in the refractive index of the switchable layer 324. Exemplarily, the switchable layer 324 can be an electrochromic material or a thermochromic material.

[0220] For example, in a phase-change-based color-changing method, the transparent conductive layer 323 applies an electrical signal (such as current) to the switchable layer 324, controlling the material of the switchable layer 324 to undergo a phase change (such as a change from crystalline to amorphous state and / or a change from metallic to insulating state), thereby causing a change in the refractive index of the switchable layer 324. Exemplarily, the switchable layer 324 can be an electrochromic material or a thermochromic material.

[0221] For example, in a color-changing method based on changes in the morphology of liquid crystal structure, the switchable layer 324 is a liquid crystal material, and the transparent conductive layer 323 applies an electrical signal (such as voltage) to the switchable layer 324 to control the rotation of the liquid crystal molecular axis, thereby causing the refractive index of the switchable layer 324 to change.

[0222] In practical applications, a suitable color-changing method can be selected based on the material of the switchable layer 324. An example is provided below for clarity.

[0223] For example, when the switchable layer 324 is a thermochromic sulfide material, the refractive index of the switchable layer 324 can be changed by a color-changing method based on phase change.

[0224] For example, when the switchable layer 324 is made of tungsten oxide, nickel oxide, or vanadium oxide, a color-changing method based on chemical reactions can be used to change the refractive index of the switchable layer 324.

[0225] For example, when the switchable layer 324 is a liquid crystal material, the refractive index of the switchable layer 324 can be changed by using a color-changing method based on the change of liquid crystal structure morphology.

[0226] Depending on the material used for the switchable layer 324 and the different color-changing principles, the field-chromic film 320 has different structures. These are described below with reference to Figures 5 to 13.

[0227] Figure 5 shows a schematic structural diagram of a filter provided in an embodiment of this application.

[0228] As shown in Figure 5, in the filter 300, the field-chromic film 320 includes at least one high-refractive-index layer 321, at least one low-refractive-index layer 322, and a transparent conductive layer 323 stacked together. One or more of the at least one high-refractive-index layer 321 are switchable layers 324, and / or one or more of the at least one low-refractive-index layer 322 are switchable layers 324, wherein the material of the switchable layer 324 is a thermochromic material (e.g., Sb₂S₃, GST, Sb₂Se₃, etc.). A current is applied to the transparent conductive layer 323, which acts as a transparent electrode and can provide a heat source for the switchable layer 324. Triggered by a temperature change, the material of the switchable layer 324 can undergo a phase change, such as a change between a crystalline and amorphous state and / or a change between an insulating and a metallic state. Accordingly, the refractive index of the switchable layer 324 can change.

[0229] For ease of understanding, referring to Figure 6, taking the change between crystalline and amorphous states of the switchable layer 324 triggered by temperature changes as an example, the transparent conductive layer 323 can provide a transient heat source, causing the material of the switchable layer 324 to undergo a rapid phase change. For example, heating under a low-voltage long pulse can cause the material of the switchable layer 324 to switch from an amorphous state to a crystalline state, while heating under a high-voltage short pulse can cause the material of the switchable layer 324 to switch from a crystalline state to an amorphous state. The refractive index of the switchable layer 324 is different in the crystalline and amorphous states. For example, referring to Figure 6, the refractive index of the switchable layer 324 in the amorphous state (3.3 in the example) is less than the refractive index in the crystalline state (3.8 in the example).

[0230] For example, the material of the switchable layer 324 can be a thermochromic sulfide phase change material. Thermochromic sulfide phase change materials are transparent to visible light in all their states, thus not affecting visible light imaging and ensuring the photographic function. Furthermore, thermochromic sulfide phase change materials can undergo phase changes via electrical pulses, and each phase remains stable at room temperature. Therefore, when switching phases of the material, it is not necessary to continuously apply an electrical signal, saving energy.

[0231] In some embodiments, when a first electrical signal is applied to the transparent conductive layer 323, the phase of the switchable layer 324 is amorphous (or crystalline), and the switchable layer 324 has a first refractive index, causing the filter 300 to be in visible light mode. When a second electrical signal is applied to the transparent conductive layer 323, the phase of the switchable layer 324 is crystalline (or amorphous), and the switchable layer 324 has a second refractive index, causing the filter 300 to be in infrared light mode.

[0232] In some embodiments, both the first electrical signal and the second electrical signal are electrical pulses, wherein the pulse width of the first electrical signal is different from the pulse width of the second electrical signal and / or the pulse amplitude of the first electrical signal is different from the pulse amplitude of the second electrical signal.

[0233] Based on the structure shown in Figure 5, there are multiple ways to position the transparent conductive layer 323, which will be illustrated below with reference to the accompanying drawings.

[0234] In one example, referring to FIG5, the transparent conductive layer 323 is located between the at least one high refractive index layer 321 and the substrate 310, and between the at least one low refractive index layer 322 and the substrate 310. That is, the distance between the transparent conductive layer 323 and the substrate 310 is less than the distance between any one of the high refractive index layers 321 and the substrate 310, and less than the distance between any one of the low refractive index layers 322 and the substrate 310. For example, the transparent conductive layer 323 is adjacent to the substrate 310. Exemplarily, the transparent conductive layer 323 is formed on one side surface of the substrate 310 in the thickness direction.

[0235] In another example, referring to Figure 7(a), the transparent conductive layer 323 is located on the side of the at least one high-refractive-index layer 321 that is away from the substrate 310, and on the side of the at least one low-refractive-index layer 322 that is also away from the substrate 310. That is, the distance between the transparent conductive layer 323 and the substrate 310 is greater than the distance between any one of the high-refractive-index layers 321 and the substrate 310, and also greater than the distance between any one of the low-refractive-index layers 322 and the substrate 310. For example, the transparent conductive layer 323 is furthest from the substrate 310 in the thickness direction of the filter.

[0236] In another example, referring to Figure 7(b), the transparent conductive layer 323 is located between the first high refractive index layer 321 of the at least one high refractive index layer 321 and the first low refractive index layer 322 of the at least one low refractive index layer 322. That is, the transparent conductive layer 323 is located between a high refractive index layer 321 and a low refractive index layer 322 in the thickness direction.

[0237] Based on the structure shown in Figure 5, there are multiple ways to set the switchable layer 324, which are illustrated below with reference to the attached figures.

[0238] In one example, referring to Figure 5 or Figure 7, a portion of the film in the at least one high-refractive-index layer 321 and / or a portion of the film in the at least one low-refractive-index layer 322 is a switchable layer 324. Having fewer switchable layers 324 reduces the complexity of control during the filter design phase.

[0239] In another example, referring to Figure 8, all layers in the at least one high-refractive-index layer 321 and / or all layers in the at least one low-refractive-index layer 322 are switchable layers 324. Having a larger number of switchable layers 324 can improve the controllability during the filter design stage.

[0240] Figure 9 shows a schematic structural diagram of another filter provided in an embodiment of this application.

[0241] As shown in Figure 9, in the filter 300, the electrochromic film 320 includes at least one high-refractive-index layer 321, at least one low-refractive-index layer 322, and two transparent conductive layers 323 stacked together. For distinction, the two transparent conductive layers 323 are referred to as the first transparent conductive layer 323a and the second transparent conductive layer 323b, respectively. One or more of the at least one high-refractive-index layer 321 is a switchable layer 324, and / or one or more of the at least one low-refractive-index layer 322 is a switchable layer 324, located between the first transparent conductive layer 323a and the second transparent conductive layer 323b. The material of the switchable layer 324 is an electrochromic material (e.g., liquid crystal, tungsten oxide, nickel oxide, vanadium oxide, etc.). The first transparent conductive layer 323a and the second transparent conductive layer 323b can apply an electrical signal (such as voltage or current) to the switchable layer 324. When triggered by a change in the electrical signal, the refractive index of the switchable layer 324 changes.

[0242] For example, the material of the switchable layer 324 is a transition metal oxide, etc. The first transparent conductive layer 323a and the second transparent conductive layer 323b can apply current to the switchable layer 324. Under the action of the current, the material of the switchable layer 324 can undergo a chemical reaction, thereby changing the refractive index of the switchable layer 324.

[0243] For example, the material of the switchable layer 324 is liquid crystal. The first transparent conductive layer 323a and the second transparent conductive layer 323b can apply voltage to the switchable layer 324. Under the action of voltage, the material of the switchable layer 324 can form different liquid crystal twist angles (that is, the rotation angle of the liquid crystal molecular axis), thereby changing the refractive index of the switchable layer 324.

[0244] For ease of understanding, referring to Figure 10, taking liquid crystal as an example with liquid crystal as the material of the switchable layer 324, a voltage is applied between the first transparent conductive layer 323a and the second transparent conductive layer 323b, causing a change in the twist angle of the liquid crystal molecules. For example, when a first voltage is applied to the switchable layer 324, the liquid crystal molecule axis rotates by a first angle; when a second voltage is applied to the switchable layer 324, the liquid crystal molecule axis rotates by a second angle. Here, the first voltage is greater than or equal to 0, the second voltage is greater than or equal to 0, and the first voltage and the second voltage are different. Both the first angle and the second angle are less than or equal to the maximum twist angle of the liquid crystal molecules, and the first angle and the second angle are different. The refractive index of the switchable layer 324 is different when the liquid crystal molecules rotate by the first angle and the second angle. For example, the refractive index of the switchable layer 324 at a smaller voltage is less than the refractive index at a larger voltage. Or, the refractive index of the switchable layer 324 at a smaller voltage is greater than the refractive index at a larger voltage.

[0245] To further illustrate, consider this example: the first voltage can be greater than 0, meaning the switchable layer 324 is energized, and the first angle can be 90°; the second voltage can be 0, meaning the switchable layer 324 is de-energized, and the second angle can be 0°. The refractive index of the switchable layer 324 under the first voltage (higher voltage) is less than the refractive index under the second voltage (lower voltage).

[0246] When the switchable layer 324 uses an electrochromic material, it has lower light loss and can improve the transmittance of the filter 300 in the working band.

[0247] Based on the structure shown in Figure 9, there are multiple ways to position the two transparent conductive layers 323, which will be illustrated below with reference to the accompanying drawings.

[0248] In one example, referring to FIG9, the at least one high refractive index layer 321 and the at least one low refractive index layer 322 are located between the first transparent conductive layer 323a and the second transparent conductive layer 323b. For example, the first transparent conductive layer 323a is closest to the substrate 310, and the second transparent conductive layer 323b is farthest from the substrate 310.

[0249] In another example, referring to FIG11, a first transparent conductive layer 323a and / or a second transparent conductive layer 323b are interposed in the stacked structure of at least one high refractive index layer 321 and at least one low refractive index layer 322, and a switchable layer 324 is located between the first transparent conductive layer 323a and the second transparent conductive layer 323b. For example, the first transparent conductive layer 323a has a high refractive index layer 321 and a low refractive index layer 322 respectively on both sides in the thickness direction, and / or the second transparent conductive layer 323b has a high refractive index layer 321 and a low refractive index layer 322 respectively on both sides in the thickness direction.

[0250] As an example and not a limitation, a first transparent conductive layer 323a, a second transparent conductive layer 323b, and a film layer located between them can be used as an intermediate film system, with thin films of alternating high and low refractive indices disposed on both sides or one side of the intermediate film system.

[0251] It is understood that, depending on the number of conventional high refractive index layer 321, conventional low refractive index layer 322, and switchable layer 324, the positions of the first transparent conductive layer 323a and the second transparent conductive layer 323b can be adjusted adaptively, and no special limitation is made here.

[0252] Based on the structure shown in Figure 9, there are multiple ways to set the switchable layer 324, which are illustrated below with reference to the attached figures.

[0253] In one example, referring to Figure 9 or Figure 11, a portion of the film in the at least one high-refractive-index layer 321 and / or a portion of the film in the at least one low-refractive-index layer 322 is a switchable layer 324. Having fewer switchable layers 324 reduces the complexity of control during the filter design phase.

[0254] In another example, referring to Figure 12, all layers in the at least one high-refractive-index layer 321 and / or all layers in the at least one low-refractive-index layer 322 are switchable layers 324. Having a larger number of switchable layers 324 can improve the controllability during the filter design stage.

[0255] Figure 13 shows a schematic structural diagram of another filter provided in an embodiment of this application.

[0256] As shown in Figure 13, in the filter 300, the field-chromic film 320 includes a plurality of high-refractive-index layers 321, a plurality of low-refractive-index layers 322, and P transparent conductive layers 323 stacked together, where P is an even number greater than 0. The P transparent conductive layers 323 are divided into P / 2 transparent electrode groups, each of which includes two adjacent transparent conductive layers 323. For distinction, these two adjacent transparent conductive layers 323 are respectively referred to as the first transparent conductive layer 323a and the second transparent conductive layer 323b. The plurality of high-refractive-index layers 321 and / or the plurality of low-refractive-index layers 322 include at least two switchable layers 324, which are dispersed between the first transparent conductive layer 323a and the second transparent conductive layer 323b in each transparent electrode group.

[0257] The switchable layer 324 is made of an electrochromic material (e.g., liquid crystal, tungsten oxide, nickel oxide, vanadium oxide, etc.). Each transparent electrode group applies an electrical signal (e.g., voltage or current) to the corresponding switchable layer 324. Under the influence of the electrical signals applied by each transparent electrode group, the refractive index of the corresponding switchable layer 324 changes.

[0258] In this embodiment, the electrical signals applied to each transparent electrode group at the same time can be the same or different.

[0259] In this way, the refractive index of different switchable layers 324 can be adjusted separately, and the refractive index of the switchable layer 324 can be adjusted more precisely to improve the control capability of the filter's operating wavelength.

[0260] In some embodiments, the number of film layers of the field-chromatic thin film 320 (i.e., the sum of the high refractive index layer 321, the low refractive index layer 322, and the transparent conductive layer 323) is greater than or equal to 10 and less than or equal to 70.

[0261] In this embodiment of the application, when the refractive index of the field-sensitive color-changing film 320 changes under the action of an electrical signal, the filter 300 is in different modes and has different transmission bands, as described below with reference to Figures 14 and 15.

[0262] As an example, referring to Figure 14(a), when a first electrical signal is applied to the field-chromic film 320, the filter 300 is in visible light mode, and the transmission band of the filter 300 includes the visible light band (e.g., band C1) but excludes the infrared light band. Referring to Figure 14(b), when a second electrical signal is applied to the field-chromic film 320, the filter 300 is in infrared light mode, and the transmission band of the filter 300 includes the infrared light band (e.g., band C2) but excludes the visible light band.

[0263] Thus, when the filter 300 is used to transmit visible light, infrared light is blocked, avoiding the influence of infrared light on visible light imaging, thereby reducing or eliminating the risk of false colors and improving the photography experience. When the filter 300 is used to transmit infrared light, the infrared light can be used for face recognition in low-light environments, shortening the unlocking time. In this embodiment, the filter does not include the visible light band when in infrared light mode. Therefore, in some cases, if infrared light is also used for face recognition in strong light environments, the filter can filter out visible light in infrared light mode, eliminating the influence of ambient visible light on face recognition.

[0264] As another example, referring to Figure 15(a), when a first electrical signal is applied to the field-chromic film 320, the filter 300 is in visible light mode, and the transmission band of the filter 300 includes the visible light band (e.g., band C1) but excludes the infrared light band. Referring to Figure 15(b), when a second electrical signal is applied to the field-chromic film 320, the filter 300 is in infrared light mode, and the transmission band of the filter 300 includes the visible light band (e.g., band C3) and the infrared light band (e.g., band C2). Here, the wavelength ranges of the visible light band C3 and the visible light band C1 can be the same or different.

[0265] In other words, by adjusting the electrical signal applied to the electrochromic film 320, the filter 300 can be made to pass through light in the visible light band in a fixed manner, and selectively pass through light in the infrared light band.

[0266] Thus, when filter 300 is used to transmit visible light, infrared light is blocked, avoiding the influence of infrared light on visible light imaging and reducing or eliminating the risk of false colors. When filter 300 is used to transmit infrared light, the infrared light can be used for face recognition in low-light environments, shortening the unlocking time. Although the transmission band of filter 300 in infrared mode also includes the visible light band, the intensity of visible light is low in low-light environments, and the visible light passing through the filter does not affect the use of infrared light for face recognition in low-light environments. Furthermore, filters with the operating band shown in Figure 15 are easy to manufacture.

[0267] Since the substrate 310 is made of transparent material, it can be assumed that the substrate 310 has virtually no function in filtering light waves. Therefore, if the filter 300 does not include other film systems used for filtering light waves, the transmission band of the filter 300 is the same as the transmission band of the field-chromic film 320. That is, when a first electrical signal is applied to the field-chromic film 320, the field-chromic film 320 has the transmission band shown in Figure 14(a) or Figure 15(a); when a second electrical signal is applied to the field-chromic film 320, the field-chromic film 320 has the transmission band shown in Figure 14(b) or Figure 15(b).

[0268] In some embodiments, band C2 shown in FIG14 or FIG15 may be the near-infrared band.

[0269] Figure 16 shows a schematic structural diagram of a filter provided in an embodiment of this application. The filter 400 shown in Figure 16 differs from the filter 300 shown in Figure 4 in that the filter 400 further includes a dual-pass film 330, which is used for transmission in the visible light band and the infrared light band.

[0270] Specifically, as shown in FIG16, the filter 400 may include a substrate 310, a field-chromic film 320, and a double-pass film 330 stacked together. In some embodiments, the field-chromic film 320 and the double-pass film 330 may be located on opposite sides of the substrate 310 in the thickness direction. In other embodiments, the field-chromic film 320 and the double-pass film 330 are located on the same side of the substrate 310 in the thickness direction, for example, the field-chromic film 320 is located between the double-pass film 330 and the substrate 310, or the double-pass film 330 is located between the field-chromic film 320 and the substrate 310.

[0271] An electrical signal is applied to the field-chromic film 320. When the magnitude of the electrical signal is adjusted, the refractive index of the field-chromic film 320 changes, and its transmission band changes accordingly. The transmission band of the double-pass film 330 is fixed. The intersection of the transmission bands of the field-chromic film 320 and the double-pass film 330 is the transmission band of the filter 400.

[0272] Therefore, by adjusting the electrical signal applied to the field-chromic film 320, the transmission band of the field-chromic film 320 can be changed. Correspondingly, the intersection of the transmission band of the field-chromic film 320 and the transmission band of the double-pass film 330 is changed, that is, the transmission band of the filter 400 is changed. For example, when the first electrical signal is applied, the filter 400 is in visible light mode, and its operating band includes the visible light band. When the second electrical signal is applied, the filter 400 is in infrared light mode, and its operating band includes the infrared light band. In other words, by adjusting the electrical signal applied to the field-chromic film 320, the operating band of the filter 400 can be switched.

[0273] Specifically, the field-chromic film 320 includes a field-chromic material, which has a first refractive index under the action of a first electrical signal, so that the transmission band of the field-chromic film 320 includes a first visible light band. The field-chromic material has a second refractive index under the action of a second electrical signal, so that the transmission band of the field-chromic film 320 includes a first infrared light band.

[0274] The transmission bands of the dual-pass film 330 are the second visible light band and the second infrared light band, wherein the second visible light band at least partially overlaps with the first visible light band, the second infrared light band at least partially overlaps with the first infrared light band, and the second infrared light band does not overlap with the transmission band of the field-chromic film under the first electrical signal.

[0275] Optionally, the field-chromic film 320, under the second electrical signal, also includes a third visible light band in its transmission band, which at least partially overlaps with the second visible light band. That is, the filter 400 can also transmit visible light in infrared mode.

[0276] For example, the maximum wavelength of the third visible light band is less than or equal to the minimum wavelength of the first infrared light band.

[0277] Optionally, the field-chromic film 320, under the first electrical signal, also includes a third infrared light band in its transmission band, which does not overlap with the second infrared light band. That is, the field-chromic film 320 can transmit infrared light under the first electrical signal, but when combined with the dual-pass film 330, it prevents the entire filter 400 from transmitting infrared light.

[0278] In this embodiment, the working band of the filter 400 is obtained by superimposing the transmission bands of the two film systems. This not only enables the switching of the working band of the filter 400, but also reduces the design difficulty of the field-chromic film 320 and makes it easy to implement.

[0279] The embodiments of the field-chromatic film 320 in the filter 300 described above are also applicable to the field-chromatic film 320 in the filter 400. For details, please refer to the previous text. For the sake of brevity, they will not be repeated here.

[0280] It should be noted that the thickness direction of the optical film or optical element (such as substrate 310, transparent conductive layer 323, filter 300, etc.) involved in this application is parallel to the optical axis.

[0281] It should also be noted that the "transmitted band" involved in the embodiments of this application refers to the light transmittance of the band being greater than a preset threshold (e.g., 60%, 70%, or 80%, which can be determined according to actual needs). Light that does not belong to this band is not necessarily unable to pass through, but its transmittance is less than the preset threshold. In other words, bands with transmittance less than the preset threshold are considered as non-compliant light and are not used as the transmitted bands of the filter. In addition, the descriptions of "visible light band," "first visible light band," "second visible light band," and "third visible light band" involved in this application mean that the corresponding band belongs to the wavelength range of visible light, and are not limited to the full wavelength of visible light. That is, "visible light band," "first visible light band," "second visible light band," and "third visible light band" are a subset (i.e., at least part) of the full wavelength range of visible light (approximately 380nm-750nm). Similarly, the descriptions of "infrared light band," "first infrared light band," "second infrared light band," and "third infrared light band" in this application refer to bands that belong to the wavelength range of infrared light, and are not limited to the full wavelength of infrared light. That is, "infrared light band," "first infrared light band," "second infrared light band," and "third infrared light band" are a subset (at least partially) of the full wavelength range of infrared light (approximately 750nm-1000μm). Generally, infrared light can be divided into near-infrared, mid-infrared, and far-infrared. For example, the "infrared light band," "first visible light band," "second visible light band," or "third visible light band" in this application can be a subset of the full wavelength range of near-infrared light (approximately 750nm-1400nm).

[0282] In some embodiments, referring to FIG17, the dual-pass film 330 may include at least one high refractive index layer 331 and at least one low refractive index layer 332, wherein the at least one high refractive index layer 331 and the at least one low refractive index layer 332 are stacked alternately, and the refractive index of the high refractive index layer 331 is greater than the refractive index of the low refractive index layer 332.

[0283] By alternating the stacking of high refractive index layer 331 and low refractive index layer 332, different order reflection peaks can be constructed, thereby adjusting the transmittance of the dual-pass film 330 for different wavelengths of light. This enables the dual-pass film 330 to have high transmittance in multiple bands and improve the passband range.

[0284] In some embodiments, the high refractive index layer 331 has a high refractive index. For example, the refractive index of the high refractive index layer 331 is greater than 1.7.

[0285] In some embodiments, the material of the high refractive index layer 331 includes, but is not limited to, titanium dioxide (TiO2), titanium pentoxide (Ti3O5), zirconium dioxide (ZrO2), and tantalum pentoxide (Ta2O5). In practical applications, the material of the high refractive index layer 331 can be selected as needed, and this application does not impose any special limitations on it. The material of the high refractive index layer 331 can be the same as or different from the material of the aforementioned conventional high refractive index layer 321.

[0286] In some embodiments, the low-refractive-index layer 332 has a low refractive index. For example, the refractive index of the low-refractive-index layer 332 is less than 1.7. Further, the refractive index of the low-refractive-index layer 332 is greater than or equal to 1.3.

[0287] In some embodiments, the material of the low refractive index layer 332 includes, but is not limited to, silicon dioxide (SiO2), magnesium fluoride (MgF2), calcium fluoride (CaF2), etc. In practical applications, the material of the low refractive index layer 332 can be selected as needed, and this application does not impose any special limitations on it. The material of the low refractive index layer 332 can be the same as or different from the material of the aforementioned conventional low refractive index layer 322.

[0288] In some embodiments, the deposition method of the high refractive index layer 331 or the low refractive index layer 332 may include, but is not limited to, electron beam evaporation, atomic layer deposition, magnetron sputtering, laser pulse deposition, etc. In practical applications, a suitable deposition method can be selected according to the material of the film.

[0289] In some embodiments, the high refractive index layer 331 is located in the odd-numbered layers of the double-pass film 330, and the low refractive index layer 332 is located in the even-numbered layers of the double-pass film 330.

[0290] The arrangement of the high-refractive-index layer 331 as an odd number of layers and the low-refractive-index layer 332 as an even number of layers enables the double-pass film 330 to achieve large-angle absorption of the transmission band.

[0291] In some embodiments, the thickness of the double-pass film 330 is greater than or equal to 1 micrometer and less than or equal to 10 micrometers.

[0292] In some embodiments, the number of film layers in the dual-pass film 330 is greater than or equal to 10 and less than or equal to 70.

[0293] In some embodiments, the thickness of the filter 400 is greater than or equal to 0.1 mm and less than or equal to 0.4 mm.

[0294] In practical applications, the thickness of filter 400 can be determined according to the specific application scenario. For example, the thickness of filter 400 can be determined with reference to the film system thickness and the substrate thickness. For instance, the film system thickness (including the thickness of the field-chromatic film 320 and the thickness of the double-pass film 330) is approximately 20μm-200μm, and the thickness of the substrate 310 is approximately 0.11mm-0.31mm.

[0295] As mentioned above, the transmission band of the field-chromatic thin film 320 and the transmission band of the dual-pass film 330 are superimposed, and their intersection is the working band of the filter 400, which is described below with reference to Figure 18.

[0296] As shown in Figure 18, the transmission bands of the dual-pass film 330 include band C4 and band C5. Band C4 is the visible light band, and band C5 is the infrared light band, for example, band C5 is the near-infrared light band. Here, band C4 is an example of a second visible light band, and band C5 is an example of a second infrared light band.

[0297] Referring to Figure 18(a), when a first electrical signal is applied to the field-chromic film 320, the transmission band of the field-chromic film 320 is band C6. The intersection of band C6 and the transmission band of the double-pass film 330 is band C1, which is a visible light band. For example, band C6 is a visible light band, or band C6 includes a visible light band and an infrared light band (e.g., band C10), where the wavelength ranges of band C10 and band C5 do not overlap. Thus, after the transmission bands of the field-chromic film 320 and the double-pass film 330 are superimposed, the operating band of the filter 400 in visible light mode is band C1. Here, band C6 is an example of a first visible light band, and band C10 is an example of a third infrared light band.

[0298] There are several possibilities regarding band C1.

[0299] For example, if the wavelength range of band C6 is within the wavelength range of band C4, then the wavelength ranges of band C1 and band C6 are the same. That is, the operating wavelength range of filter 400 in visible light mode is the same as the transmission wavelength range of field-chromic film 320.

[0300] For example, if the wavelength range of band C4 is within the wavelength range of band C6, then the wavelength ranges of band C1 and band C4 are the same. That is, the operating wavelength range of filter 400 in visible light mode is the same as the visible light transmission wavelength range of the dual-pass film 330.

[0301] For example, if the wavelength range of band C4 partially overlaps with that of band C6, for ease of description, the overlapping band will be referred to as the first overlapping band below. Then, band C1 has the same wavelength range as the first overlapping band.

[0302] Referring to Figure 18(b), when a second electrical signal is applied to the field-chromic film 320, the transmission band of the field-chromic film 320 is band C7, which includes bands C8 and C9. Band C8 is the visible light band, and band C9 is the infrared light band, such as the near-infrared light band. After the transmission bands of the field-chromic film 320 and the double-pass film 330 are superimposed, the operating bands of the filter 400 in infrared mode are obtained as bands C2 and C3, where band C3 is the visible light band and band C2 is the infrared light band. Here, the wavelength ranges of bands C8 and C6 can be the same or different. Correspondingly, the wavelength ranges of bands C3 and C1 can be the same or different. The wavelength range of band C9 is different from that of band C10. Here, band C9 is an example of the first infrared light band, and band C8 is an example of the third visible light band.

[0303] There are several possibilities regarding band C3.

[0304] For example, if the wavelength range of band C8 is within the wavelength range of band C4, then the wavelength ranges of band C3 and band C8 are the same. That is, the visible light operating band of filter 400 in infrared mode is the same as the visible light transmission band of field-chromic film 320.

[0305] For example, if the wavelength range of band C4 is within the wavelength range of band C8, then the wavelength ranges of band C3 and band C4 are the same. That is, the visible light operating band of filter 400 in infrared mode is the same as the visible light transmission band of the dual-pass film 330.

[0306] For example, if the wavelength range of band C4 partially overlaps with that of band C8, for ease of description, the overlapping band will be referred to as the second overlapping band below. Then, band C3 has the same wavelength range as the second overlapping band.

[0307] There are several possibilities regarding band C2.

[0308] For example, if the wavelength range of band C9 is within the wavelength range of band C5, then the wavelength ranges of band C2 and band C9 are the same. That is, the infrared light operating band of filter 400 in infrared light mode is the same as the infrared light transmission band of field-chromic film 320.

[0309] For example, if the wavelength range of band C5 is within the wavelength range of band C9, then the wavelength ranges of band C2 and band C5 are the same. That is, the infrared light operating band of filter 400 in infrared light mode is the same as the infrared light transmission band of the dual-pass film 330.

[0310] For example, if the wavelength range of band C5 partially overlaps with that of band C9, for ease of description, the overlapping band will be referred to as the third overlapping band below. Then, the wavelength range of band C2 is the same as that of the third overlapping band.

[0311] There are several ways to set the transmission band of the dual-pass film 330.

[0312] In one example, similar to the transmission band schematic diagram of the field-chromic thin film 320 shown in Figure 18(b), the transmission band of the dual-pass thin film 330 is a continuous wavelength range, that is, there is no gap between the visible light band (i.e., band C4) and the infrared light band (i.e., band C5), or in other words, the maximum wavelength of the visible light band is equal to the minimum wavelength of the infrared light band. This can reduce the design difficulty of the dual-pass thin film 330.

[0313] In another example, referring to Figure 18(a) or (b), the visible light band (i.e., band C4) and the infrared light band (i.e., band C5) of the dual-pass film 330 are spaced apart, or in other words, the maximum wavelength of the visible light band is smaller than the minimum wavelength of the infrared light band. This results in a narrower filtering range for the dual-pass film 330, stronger restriction on light transmission, and reduces the design complexity of the field-chromic film 320.

[0314] There are several ways to set the transmission band of the field-chromic film 320.

[0315] In one example, referring to Figure 18(b), when a second electrical signal is applied to the field-chromic film 320, the transmission band of the field-chromic film 320 is a continuous wavelength range, that is, there is no gap between the visible light band (i.e., band C8) and the infrared light band (i.e., band C9), or in other words, the maximum wavelength of the visible light band is equal to the minimum wavelength of the infrared light band.

[0316] In another example, similar to the transmission band schematic diagram of the dual-pass film 330 shown in Figure 18(a), when a second electrical signal is applied to the field-chromic film 320, there is a gap between the visible light band (i.e., band C8) and the infrared light band (i.e., band C9) in the transmission band of the field-chromic film 320, or in other words, the maximum wavelength of the visible light band is smaller than the minimum wavelength of the infrared light band.

[0317] In some embodiments, referring to FIG18(a), when a first electrical signal is applied to the field-chromic film 320, if the transmission band of the field-chromic film 320 includes a visible light band and an infrared light band, then the visible light band and the infrared light band can form a continuous wavelength range or have intervals.

[0318] In some embodiments, referring to FIG18, the minimum wavelength value of the field-chromic film 320 in the transmission band under the first electrical signal (e.g., the left end value of band C6) is less than or equal to the minimum wavelength value of the field-chromic film 320 in the transmission band under the second electrical signal (e.g., the left end value of band C8). The maximum wavelength value of the field-chromic film 320 in the transmission band under the first electrical signal (e.g., the right end value of band C6, or the right end value of band C10) is less than the maximum wavelength value of the field-chromic film 320 in the transmission band under the second electrical signal (e.g., the right end value of band C9).

[0319] Thus, when switching from the second electrical signal to the first electrical signal, the transmission band of the field-chromic film 320 shifts towards the short-wave direction, which is beneficial to ensure that the transmission band of the field-chromic film 320 under the first electrical signal includes the visible light band and does not overlap with the infrared light band of the dual-pass film 330.

[0320] Based on the transmission band settings of the field-chromatic thin film 320 and the transmission band settings of the dual-pass thin film 330, the filter 400 has the following two modes of operation in infrared mode.

[0321] In one embodiment, if the transmission band of the field-chromic film 320 and the transmission band of the dual-pass film 330 are both continuous wavelength ranges when the second electrical signal is applied, then band C2 and band C3 can form a continuous wavelength range, that is, the maximum wavelength of band C3 is equal to the minimum wavelength of band C2.

[0322] In another embodiment, if the transmission band of the field-chromic film 320 and / or the transmission band of the dual-pass film 330 are discontinuous wavelength ranges when the second electrical signal is applied, then there is a gap between band C2 and band C3, that is, the maximum wavelength of band C3 is less than the minimum wavelength of band C2.

[0323] It is understood that Figure 18 describes the field-chromic film 320 under the second electrical signal by taking the transmission band of the field-chromic film 320 as including the visible light band and the infrared light band as an example. In some other embodiments, the transmission band of the field-chromic film 320 under the second electrical signal may only include the infrared light band (e.g., band C9) and not include the visible light band (e.g., band C8).

[0324] As mentioned in the above embodiments, the field-chromic film 320 includes a switchable layer 324, which can change its refractive index under different electrical signals. Generally, filters have the following physical law 1): when the filter material changes from a low refractive index to a high refractive index, the passband shifts towards longer wavelengths; when the filter material changes from a high refractive index to a low refractive index, the passband shifts towards shorter wavelengths. In practice, this law can be used to design the passband range of the field-chromic film 320 under the first and second electrical signals, respectively.

[0325] Referring to Figure 19(a), when the filter 400 is in infrared mode, a second electrical signal is applied to the field-chromic film 320. As shown by the solid line in the figure, the transmission bands of the field-chromic film 320 include the visible light band B1 and the infrared light band B2. As shown by the dashed line in the figure, the transmission bands of the dual-pass film 330 include the visible light band A1 and the infrared light band A2. In the dotted area shown in the figure, the visible light band A1 and the visible light band B1 can overlap, and the infrared light band A2 and the infrared light band B2 can overlap. Therefore, the operating bands of the filter 400 in infrared mode include the visible light band A1 (or B1) and the infrared light band A2 (or B2).

[0326] Referring to Figure 19(b), if the electrical signal applied to the field-chromic film 320 is changed to switch the switchable layer 324 from a relatively low refractive index to a relatively high refractive index, as shown by the solid line in the figure, the transmission band of the field-chromic film 320 will shift towards longer wavelengths. Since the transmission band of the dual-pass film 330 is the same as the transmission band of the field-chromic film 320 in infrared mode, it can be seen from Figure 19(b) that the transmission band of the field-chromic film 320 shifts towards longer wavelengths relative to the transmission band of the dual-pass film 330. When band B2 shown in Figure 19(a) moves to band B4 shown in Figure 19(b), band B4 does not overlap with the infrared band A2 of the dual-pass film 330. Thus, even if the field-chromic film 320 can transmit light in band B4, it will be blocked by the dual-pass film 330. When band B1 shown in Figure 19(a) moves to band B3 shown in Figure 19(b), band B3 partially overlaps with the visible light band A1 of the dual-pass film 330, so visible light can still pass through the field-chromic film 320 and the dual-pass film 330. In this case, the overlap of the transmission bands of the field-chromic film 320 and the dual-pass film 330 includes the visible light band (as shown in the dotted area), but excludes the infrared band, which meets the aforementioned requirement for the transmission band of the filter 400 in visible light mode. Therefore, the transmission band in this mode can be designed as the transmission band of the filter 400 in visible light mode. Correspondingly, the electrical signal applied to the field-chromic film 320 in this mode is the first electrical signal.

[0327] Alternatively, referring to Figure 19(c), if the electrical signal applied to the field-chromic film 320 is changed to switch the switchable layer 324 from a relatively high refractive index to a relatively low refractive index, as shown by the solid line in the figure, the transmission band of the field-chromic film 320 will shift towards shorter wavelengths. Since the transmission band of the dual-pass film 330 is the same as the transmission band of the field-chromic film 320 in infrared mode, it can be seen from Figure 19(c) that the transmission band of the field-chromic film 320 shifts towards shorter wavelengths relative to the transmission band of the dual-pass film 330. When band B2 shown in Figure 19(a) shifts to band B6 shown in Figure 19(c), band B6 does not overlap with the infrared band A2 of the dual-pass film 330. Thus, even if the field-chromic film 320 can transmit light in band B6, it will be blocked by the dual-pass film 330. When band B1 shown in Figure 19(a) moves to band B5 shown in Figure 19(b), band B5 partially overlaps with the visible light band A1 of the dual-pass film 330, so visible light can still pass through the field-chromic film 320 and the dual-pass film 330. In this case, the overlap of the transmission bands of the field-chromic film 320 and the dual-pass film 330 includes the visible light band (as shown in the dotted area), but excludes the infrared band, which meets the aforementioned requirement for the transmission band of the filter 400 in visible light mode. Therefore, the transmission band in this mode can be designed as the transmission band of the filter 400 in visible light mode. Correspondingly, the electrical signal applied to the field-chromic film 320 in this mode is the first electrical signal.

[0328] Based on the above physical laws, 1) the transmission band of the field-chromic thin film 320 is designed with lower requirements for the control of electrical signals.

[0329] In some embodiments, the refractive index switching amplitude Δn of the switchable layer 324 (i.e., the field-chromic material in the field-chromic film 320) ranges from 0.1 to 4. Here, Δn is the absolute value of the difference between the first refractive index and the second refractive index.

[0330] Generally, the larger the refractive index switching amplitude Δn of the switchable layer 324, the larger the passband shift of the field-chromic film 320, which enables the field-chromic film 320 to be further away from the infrared light transmission band of the dual-pass film 330 in visible light mode, thereby effectively achieving the cutoff effect of the filter on infrared light in visible light mode.

[0331] In some embodiments, when a first electrical signal is applied to the field-chromic film 320, the switchable layer 324 has a relatively low refractive index, and when a second electrical signal is applied to the field-chromic film 320, the switchable layer 324 has a relatively high refractive index. In other words, when the filters 300 / 400 are in visible light mode, the switchable layer 324 has a first refractive index, and when the filters 300 / 400 are in infrared light mode, the switchable layer 324 has a second refractive index, wherein the first refractive index is less than the second refractive index. Accordingly, the transmission band of the field-chromic film 320 under the first electrical signal is obtained by shifting the transmission band of the field-chromic film 320 under the second electrical signal towards a shorter wavelength. This avoids the risk of false colors when the filter 400 switches from infrared light mode to visible light mode.

[0332] The principle is explained below with reference to the accompanying diagram. Generally, filters also have the following physical law 2): When the angle of incidence of light incident on the filter changes from 0° to a larger angle, the passband shifts towards the short-wavelength direction.

[0333] As shown in the first curve in Figure 20(a), when a second electrical signal is applied, the transmittance bands of the field-chromatic thin film 320 at a small incident angle (e.g., 0°) are the visible light band D1 and the infrared light band D2, as shown by the solid lines in the figure. Since the angle of incident light may change, the transmittance curve of the field-chromatic thin film 320 will shift. For example, when the incident angle is 30°, the transmittance bands of the field-chromatic thin film 320 are the bands D1' and D2', as shown by the dashed lines in the figure, where bands D1' and D2' shift to the shortest wavelength direction relative to bands D1 and D2, respectively, i.e., shift to the left.

[0334] Similarly, as shown in the second curve in Figure 20(a), the transmission bands of the dual-pass film 330 at small angles (e.g., 0°) are the visible light band D3 and the infrared light band D4, as shown by the solid lines in the figure. Since the angle of incident light may change, the transmittance curve of the dual-pass film 330 will shift. For example, when the incident angle is 30°, the transmission bands of the dual-pass film 330 are bands D3' and D4', as shown by the dashed lines in the figure, where bands D3' and D4' shift to shorter wavelengths relative to bands D3 and D4, respectively, i.e., shift to the left.

[0335] As shown in the third curve in Figure 20(a), when a second electrical signal is applied to the field-chromatic thin film 320, the overlapping bands of the field-chromatic thin film 320 and the dual-pass film 330 at small angles (e.g., 0°) are the visible light band D5 and the infrared light band D6, and at large angles (e.g., 30°) are the visible light band D5' and the infrared light band D6'. Bands D5 and D6 represent the passband range of the filter 400 at small angles, and bands D5' and D6' represent the passband range of the filter 400 at large angles. Bands D5' and D6' shift to the shortwave direction relative to bands D5 and D6, respectively, i.e., shift to the left.

[0336] When the above physical law 1) is used to design the transmission band of the filter 400 in the visible light mode, if the first refractive index is greater than the second refractive index, when the filter 400 switches from the infrared light mode to the visible light mode, the switchable layer 324 switches from the lower refractive index to the higher refractive index under the action of the first electrical signal, and the transmission band of the field-chromic film 320 moves to the long-wave direction accordingly.

[0337] Referring to the first curve shown in Figure 20(b), after the switchable layer 324 switches from a lower refractive index to a higher refractive index, the transmission band of the field-chromic film 320 at small angles (e.g., 0°) shifts from bands D1 and D2 shown in Figure 20(a) to bands D7 and D8 shown in Figure 20(b), i.e., shifts to the right. Referring to the second and third curves shown in Figure 20(b), the band D7 overlaps with the band D3 of the double-pass film 330 in the visible light band D9, while band D8 does not overlap with the band D4 of the double-pass film 330. Therefore, the transmission band of the filter 400 at small angles includes the visible light band D9, but excludes the infrared band.

[0338] Referring again to the first curve shown in Figure 20(b), due to the aforementioned rule 2), the transmission band of the field-chromic film 320 at large angles will shift to the shorter wavelength direction (i.e., shift to the left) relative to the transmission band at small angles. For example, the transmission bands of the field-chromic film 320 at an incident angle of 30° are bands D7' and D8', where bands D7' and D8' shift to the left relative to the transmission bands D7 and D8 at an incident angle of 0°, respectively. Referring to the second and third curves shown in Figure 20(b), the overlapping band of band D7' and the transmission band D3' of the double-pass film 330 at an incident angle of 30° is the visible light band D9'. At the same time, the overlapping band of band D8' and the transmission band D4' of the double-pass film 330 at an incident angle of 30° is the infrared light band D10'. In other words, the transmission band of filter 400 at large angles includes the visible light band D9', and also includes the infrared light band D10'.

[0339] Based on the above analysis, if the first refractive index is greater than the second refractive index, when the filter 400 switches from infrared mode to visible light mode, the transmission band of the field-chromic film 320 will shift to the right due to the change in the refractive index of the switchable layer 324, and to the left at large angles. This results in an overlap between the transmission bands of the field-chromic film 320 and the dual-pass film 330 at large angles in the infrared band. Thus, when the filter 400 is in visible light mode, it can transmit both visible and infrared light at large angles. If the filter 400 is used in a photography scenario, false color may occur.

[0340] Conversely, if the first refractive index is less than the second refractive index, when the filter 400 switches from infrared mode to visible mode, the transmission band of the field-chromic film 320 will shift towards shorter wavelengths (i.e., to the left) due to the change in the refractive index of the switchable layer 324. At large angles, its transmission band continues to shift towards shorter wavelengths. Therefore, the transmission bands of the field-chromic film 320 and the dual-pass film 330 at large angles do not overlap in the infrared band, thus avoiding the risk of false colors. A specific example will illustrate this below.

[0341] Figure 21 shows a schematic diagram of the transmittance curve of a filter provided in an embodiment of this application.

[0342] The descriptions of the curves shown in Figure 21(a) are the same as those in Figure 20(a), and will not be repeated here. The difference is that when the filter 400 switches from infrared mode to visible mode, the switchable layer 324 switches from a higher refractive index to a lower refractive index under the action of the first electrical signal. Correspondingly, the transmission band of the field-chromic film 320 shifts to the short-wave direction, that is, to the left.

[0343] Referring to the first curve shown in Figure 21(b), after the switchable layer 324 switches from a higher refractive index to a lower refractive index, the transmission band of the field-chromic film 320 at small angles (e.g., 0°) shifts from bands D1 and D2 shown in Figure 21(a) to bands E1 and E2 shown in Figure 21(b), i.e., a leftward shift. Referring to the second and third curves shown in Figure 21(b), the band E1 overlaps with the band D3 of the double-pass film 330 in the visible light band E3, while band E2 does not overlap with the band D4 of the double-pass film 330. Therefore, the transmission band of the filter 400 at small angles includes the visible light band E3, but excludes the infrared light band.

[0344] Referring again to the first curve shown in Figure 21(b), due to rule 2) above, the transmission band of the field-chromic film 320 at large angles will shift to the shorter wavelength direction (i.e., shift to the left) relative to the transmission band at small angles. For example, the transmission bands of the field-chromic film 320 at an incident angle of 30° are bands E1' and E2', where bands E1' and E2' shift to the left relative to the transmission bands E1 and E2 at an incident angle of 0°, respectively. Referring to the second and third curves shown in Figure 21(b), the overlapping band of band E1' and the transmission band D3' of the double-pass film 330 at an incident angle of 30° is the visible light band E3', and the non-overlapping band of band E3' and the transmission band D4' of the double-pass film 330 at an incident angle of 30° is the visible light band E3'. That is to say, the transmission band of the filter 400 at large angles includes the visible light band E3', but does not include the infrared band.

[0345] Thus, when the filter 400 is in visible light mode, it can transmit visible light at large angles but not infrared light, thereby avoiding the risk of false colors.

[0346] Figure 22 shows a schematic diagram of the transmittance curve of another filter provided in an embodiment of this application. Unlike Figure 21, the field-chromic film 320 shown in Figure 22 has a continuous transmittance band in infrared mode that includes both visible and infrared light bands.

[0347] As shown in the first curve of Figure 22(a), when a second electrical signal is applied, the transmittance band of the field-chromatic thin film 320 at a small incident angle (e.g., 0°) is band F1, as indicated by the solid line in the figure. Band F1 includes both visible and infrared light bands. Because the angle of incident light may change, the transmittance curve of the field-chromatic thin film 320 will shift. For example, when the incident angle is 30°, the transmittance band of the field-chromatic thin film 320 is band F1', as indicated by the dashed line in the figure. Band F1' shifts to the left relative to band F1, moving towards shorter wavelengths.

[0348] Similarly, as shown in the second curve in Figure 22(a), the transmission bands of the dual-pass film 330 at small angles (e.g., 0°) are the visible light band D3 and the infrared light band D4, as shown by the solid lines in the figure. Since the angle of incident light may change, the transmittance curve of the dual-pass film 330 will shift. For example, when the incident angle is 30°, the transmission bands of the dual-pass film 330 are bands D3' and D4', as shown by the dashed lines in the figure, where bands D3' and D4' shift to shorter wavelengths relative to bands D3 and D4, respectively, i.e., shift to the left.

[0349] As shown in the third curve of Figure 22(a), when a second electrical signal is applied to the field-chromatic thin film 320, the overlapping bands of the field-chromatic thin film 320 and the dual-pass film 330 at small angles (e.g., 0°) are the visible light band F2 and the infrared light band F3, and at large angles (e.g., 30°) the overlapping bands are the visible light band F2' and the infrared light band F3'. Bands F2 and F3 are the passband ranges of the filter 400 at small angles, and bands F2' and F3' are the passband ranges of the filter 400 at large angles. Bands F2' and F3' are shifted to the shortest wavelength direction relative to bands F2 and F3, i.e., shifted to the left.

[0350] When the above physical law 1) is used to design the transmission band of the filter 400 in visible light mode, if the first refractive index is less than the second refractive index, when the filter 400 switches from infrared light mode to visible light mode, the switchable layer 324 switches from a higher refractive index to a lower refractive index under the action of the first electrical signal. Correspondingly, the transmission band of the field-chromic film 320 moves to the short-wave direction, that is, to the left.

[0351] Referring to the first curve shown in Figure 22(b), after the switchable layer 324 switches from a higher refractive index to a lower refractive index, the transmission band of the field-chromic film 320 at small angles (e.g., 0°) shifts from band F1 shown in Figure 22(a) to band F4 shown in Figure 22(b), i.e., shifts to the left. Referring to the second and third curves shown in Figure 22(b), the band F4 overlaps with the band D3 of the double-pass film 330 in the visible light band F5, while band F4 does not overlap with the band D4 of the double-pass film 330. Therefore, the transmission band of the filter 400 at small angles includes the visible light band F5, but excludes the infrared band.

[0352] Referring again to the first curve shown in Figure 22(b), due to rule 2) above, the transmission band of the field-chromic film 320 at large angles will shift to the shorter wavelength direction (i.e., shift to the left) relative to the transmission band at small angles. For example, the transmission band of the field-chromic film 320 at an incident angle of 30° is band F4', where band F4' shifts to the left relative to the transmission band F4 at an incident angle of 0°. Referring to the second and third curves shown in Figure 22(b), the overlapping band of band F4' and the transmission band D3' of the double-pass film 330 at an incident angle of 30° is the visible light band F5', while the band F4' and the transmission band D4' of the double-pass film 330 at an incident angle of 30° do not overlap. In other words, the transmission band of the filter 400 at large angles includes the visible light band F5', but does not include the infrared band.

[0353] Thus, when the filter 400 is in visible light mode, it can transmit visible light at large angles but not infrared light, thereby avoiding the risk of false colors.

[0354] It should be noted that the band ranges shown in the accompanying drawings are merely exemplary, and in application, each band range can be determined according to actual needs. Furthermore, in Figures 20 to 22, the magnitude of the passband shift caused by rule 1) or rule 2) is only illustrative and should not be construed as a limitation of this application. If multiple passbands exist, they may merge during the shift process; for example, two independent passband ranges may form a continuous passband range during the shift. Additionally, the shapes of the transmittance curves shown in the accompanying drawings are merely exemplary; in practical applications, the transmittance curves of optical films may exhibit local fluctuations. Generally, when the transmittance is greater than a certain percentage, the optical film can be considered to be able to transmit light in that band.

[0355] In the above embodiments, the field-chromic film 320 and the dual-pass film 330 can be disposed on the same substrate 310 to form an integral structure.

[0356] In some other embodiments, the field-chromatic film 320 and the dual-pass film 330 can be disposed on different substrates, thereby forming two relatively independent filter structures. Referring to FIG23(a), the first filter 510 includes a first substrate 311 and a field-chromatic film 320 stacked together, and the field-chromatic film 320 can be the field-chromatic film 320 in filter 400. Referring to FIG23(b), the second filter 520 includes a second substrate 312 and a dual-pass film 330 stacked together, and the dual-pass film 330 can be the dual-pass film 330 in filter 400. The function achieved by the combination of the first filter 510 and the second filter 520 is the same as the function achieved by filter 400, and will not be described again here.

[0357] The architecture of the field-chromic thin film 320 has been introduced above with reference to Figures 5 to 23. The design method of the field-chromic thin film 320 is described below.

[0358] In this embodiment, the field-chromatic thin film 320 is a multilayer thin film structure. During the design phase, by rationally designing the thickness and refractive index of each thin film, the transmission and interference effects of light can be controlled, thereby achieving the regulation of the reflection, transmission and absorption characteristics of light, and thus realizing the optical performance of the filter within a specific wavelength range.

[0359] In some embodiments, the field-sensitive film 320 can be designed based on conventional methods, reflection methods, optical similarity techniques, etc.

[0360] The traditional method is a design approach based on optical principles and experience, which determines the optimal thin film structure by analyzing the optical properties and electromagnetic field distribution of the thin film.

[0361] The reflection method is a method to optimize thin film structure by measuring the reflection spectrum or transmission spectrum, which can check and adjust the performance of the thin film in real time.

[0362] Optical similarity techniques are numerical calculation-based methods that simulate the propagation and reflection of light in a thin film structure by building a model on a computer, thereby determining the optimal thin film design. Examples of optical similarity techniques include the transfer matrix method (TMM).

[0363] The Transmission Matrix Method (TMM) is an approximation method based on wave optics theory. It divides the optical system into a series of thin slices, represents the transmission characteristics of each slice as a transmission matrix, and then multiplies the transmission matrices of each slice to obtain the transmission matrix of the entire system, thus describing the transmission characteristics of the whole system. The transmission matrix is ​​a second-order square matrix that can convert the amplitude and phase of the incident light into the amplitude and phase of the outgoing light, thus completely describing the light transmission process. The TMM method uses the product of the transmission matrices of multiple slices to describe the transmission characteristics of the system, avoiding complex differential equation solutions or numerical simulations, and thus accelerating computation.

[0364] To facilitate understanding, the design method of field-chromatic thin film 320 will be introduced below using the transfer matrix method as an example.

[0365] Figure 24 shows a schematic diagram of the ideal transmittance curve of the field-chromic film 320. Specifically, Figure 24(a) shows the ideal transmittance curve of the field-chromic film 320 when the filter is in the aforementioned visible light mode; Figure 24(b) shows the ideal transmittance curve of the field-chromic film 320 when the filter is in the aforementioned infrared light mode. For ease of description, the state of the field-chromic film 320 when the filter is in the aforementioned visible light mode will be referred to as state A; and the state of the field-chromic film 320 when the filter is in the aforementioned infrared light mode will be referred to as state B.

[0366] The field-chromatic thin film 320 is a multilayer optical film system, and its overall characteristic matrix M can be expressed as the following formula (1):

[0367] In formula (1):

[0368] n is the total number of optical film layers included in the field-chromatic thin film 320, and n is an integer greater than 1;

[0369] M jLet be the characteristic matrix of the j-th layer of the field-chromatic thin film 320, where j is an integer greater than or equal to 1 and less than or equal to n.

[0370] Specifically, M j It can be obtained through the following formula (2).

[0371] In formula (2):

[0372] δ j The phase corresponding to the optical path length of a light wave of a preset wavelength traveling in the j-th thin film layer;

[0373] η j The effective admittance of a light wave of a preset wavelength traveling in the j-th thin film layer;

[0374] i is the imaginary unit.

[0375] The combined admittance Y of the field-chromatic thin film 320 and the substrate (such as substrate 310 or the first substrate 311) is obtained by formulas (3) and (4):

[0376] In formula (4):

[0377] M is the overall characteristic matrix of the field-chromatic thin film 320, which can be obtained by the above formulas (1) and (2);

[0378] η n+1 Admittance based on the base.

[0379] Accordingly, the transmittance T of the light wave at the preset wavelength can be obtained by formula (5):

[0380] In formula (5):

[0381] η0 is the admittance of air;

[0382] Y is the combined admittance of the field-chromic thin film 320 and the substrate, which can be obtained by formulas (4) and (5) above.

[0383] It is understandable that light of different wavelengths has different transmittance, and the transmittance of each wavelength can be obtained by formula (5).

[0384] During the design phase, the ideal and actual curves of the field-chromic film 320 in state A can be divided into corresponding multiple bands, and the ideal and actual curves of the field-chromic film 320 in state B can be divided into corresponding multiple bands. For example, as shown in Figure 24(a), the ideal curve of the field-chromic film 320 in state A can be divided into the following bands: b 1,1,tar b 1,2,tar b1,3,tar b 1,4,tar b 1,5,tar Corresponding to the range and number of bands into which the ideal curve for state A is divided, the actual curve of the field-chromatic thin film 320 in state A can be divided into the following bands: b 1,1 b 1,2 b 1,3 b 1,4 b 1,5 , where b 1,1 b 1,2 b 1,3 b 1,4 b 1,5 The wavelength ranges are respectively with b 1,1,tar b 1,2,tar b 1,3,tar b 1,4,tar b 1,5,tar Corresponding to the wavelength range. As shown in Figure 24(b), the ideal curve of the field-chromatic thin film 320 in state B can be divided into the following bands: b 2,1,tar b 2,2,tar b 2,3,tar b 2,4,tar b 2,5,tar Corresponding to the range and number of bands divided for the ideal curve of state B, the actual curve of the field-chromatic thin film 320 in state B can be divided into the following bands: b 2,1 b 2,2 b 2,3 b 2,4 b 2,5 , where b 2,1 b 2,2 b 2,3 b 2,4 b 2,5 The wavelength ranges are respectively with b 2,1,tar b 2,2,tar b 2,3,tar b 2,4,tar b 2,5,tar The wavelength range corresponds to this.

[0385] The quality factor FOM1 of the field-chromic film 320 in state A can be obtained by the following formula (6):

[0386] In formula (6):

[0387] m is the number of bands into which the ideal or actual curve of the field-chromatic thin film 320 is divided when it is in state A.

[0388] The weight of the i-th band when the field-chromatic thin film 320 is in state A;

[0389] When the field-chromatic thin film 320 is in state A, the transmittance of the i-th band on the actual curve can be obtained by formula (5);

[0390] When the field-chromatic thin film 320 is in state A, the transmittance of the i bands on the ideal curve can be obtained from the ideal curve.

[0391] λ is the wavelength;

[0392] The transmittance spectrum of the i-th band on the actual curve and the transmittance spectrum of the i-th band on the ideal curve when the field-chromatic thin film 320 is in state A is the difference between the transmittance spectrum of the i-th band on the actual curve and the transmittance spectrum of the i-th band on the ideal curve.

[0393] The quality factor FOM2 of the field-chromic film 320 in state B can be obtained by the following formula (7):

[0394] In formula (7):

[0395] q is the number of bands into which the ideal or actual curve of the field-chromatic thin film 320 is divided when it is in state B;

[0396] The weight of the i-th band when the field-chromatic thin film 320 is in state B;

[0397] When the field-chromatic thin film 320 is in state B, the transmittance of the i-th band on the actual curve can be obtained by formula (5);

[0398] When the field-chromatic thin film 320 is in state B, the transmittance of the i bands on the ideal curve can be obtained from the ideal curve.

[0399] λ is the wavelength;

[0400] The transmittance spectrum of the i-th band on the actual curve and the transmittance spectrum of the i-th band on the ideal curve when the field-chromatic thin film 320 is in state B.

[0401] Since the field-chromic film 320 has two states, namely state A and state B, it is necessary to design the transmittance curves of the film system in both states. In some embodiments, the overall quality factor (FOM) of the field-chromic film 320 can be expressed as the following formula (8): FOM=w1*FOM1+w2*FOM2 (8)

[0402] In formula (8):

[0403] w1 is the weight of the quality factor FOM1 when the field-chromic film 320 is in state A. FOM1 can be obtained by formula (6).

[0404] w2 is the weight of the quality factor FOM2 when the field-chromic film 320 is in state B. FOM2 can be obtained by formula (7).

[0405] During the design process, the final transmittance curves of the field-chromatic film 320 in state A and state B are obtained by optimizing the FOM to a minimum.

[0406] It is understood that the design method of the field-chromatic thin film 320 provided in the embodiments of this application can be applied to the aforementioned filter 300, filter 400 and first filter 510.

[0407] In this embodiment, the filter with the field-chromatic thin film 320 can be positioned in the camera module in various ways, which will be described below with reference to the accompanying drawings.

[0408] In one example, referring to FIG25, a filter having a field-chromatic film 320, such as the aforementioned filter 300 or 400, can be disposed between the lens group 221 and the image sensor 242.

[0409] In another example, referring to FIG26, a filter having a field-chromatic film 320, such as the aforementioned filter 300 or 400, can be disposed between the lens group 221 and the protective lens 104, for example, disposed on the side of the protective lens 104 facing the lens group 221.

[0410] In yet another example, referring to FIG27, a filter having a field-chromatic film 320, such as the aforementioned filter 300 or 400, can be disposed in lens group 221, for example, between two adjacent lenses, or on the object side of the first lens along the optical axis, or on the image side of the last lens along the optical axis. Exemplarily, the filter can be attached to the lens.

[0411] In another example, referring to FIG28, if the field-chromatic film 320 and the dual-pass film 330 are two relatively independent filters, the filter with the field-chromatic film 320 (e.g., the aforementioned first filter 510) and the filter with the dual-pass film 330 (e.g., the aforementioned second filter 520) can be arranged adjacently or spaced apart. The placement of the first filter 510 or the second filter 520 can be referred to FIG25 to FIG27. For example, as shown in FIG28, the first filter 510 can be disposed between the lens group 221 and the protective lens 104, and the second filter 520 can be disposed between the lens group 221 and the image sensor 242.

[0412] Figure 29 shows a schematic diagram of a camera module provided in an embodiment of this application. The camera module 600 shown in Figure 29 can be a specific example of the camera module 200 shown in Figure 3.

[0413] As shown in Figure 29, the camera module 600 includes a lens assembly 220, an image sensor 242, and a filter provided in the aforementioned embodiments, such as filter 300 or 400. The placement of the filters 300 / 400 can be referred to Figures 25 to 27. For example, the filters 300 / 400 are located between the lens assembly 220 and the image sensor 242. The lens assembly 220 projects an imaging beam from the subject onto the image sensor 242, which can be used for visible light imaging and infrared light imaging. The filters 300 / 400 are used for filtering light and can switch the filtering state to switch the operating mode of the camera module 600. For a brief description of the lens assembly 220 and the image sensor 242, please refer to the foregoing descriptions; for brevity, they will not be repeated here.

[0414] In this embodiment, the camera module 600 can be a front-facing camera or a rear-facing camera.

[0415] In some embodiments, the camera module 600 further includes an infrared emitting module 250 for emitting infrared light. When the filters 300 / 400 are in infrared light mode, the infrared light emitted by the infrared emitting module 250 can pass through the filters 300 / 400. Exemplarily, the infrared emitting module 250 can emit near-infrared light. Exemplarily, the infrared emitting module 250 is used to emit a fourth infrared light band, which at least partially overlaps with a second infrared light band and at least partially overlaps with a first infrared light band. For example, the infrared emitting module 250 emits a beam with a single center wavelength (e.g., 940nm, 810nm, or 850nm). By way of example and not limitation, the range of infrared light emitted by the infrared emitting module 250 is: center wavelength ±10nm.

[0416] In some embodiments, the infrared emitting module 250 can be a laser emitter, such as a vertical-cavity surface-emitting laser. Laser emitters emit lasers with good monochromaticity, high power, and can be modulated at high frequencies, exhibiting the ability to operate stably for extended periods.

[0417] In some embodiments, the infrared emitting module 250 can always be in an active state, which reduces control complexity and, even when the filters 300 / 400 are in visible light mode, can block the infrared light emitted by the infrared emitting module 250, thus preventing it from adversely affecting the performance of the camera module 600. Alternatively, the infrared emitting module 250 can be in an active state only when the filters 300 / 400 are in infrared light mode, and in a non-active state at other times, thus saving power consumption.

[0418] In some other embodiments, the filters 300 / 400 in the camera module 600 can also be replaced with the aforementioned first filter 510 and second filter 520. The filtering state of the first filter 510 can be switched, and in conjunction with the second filter 520, the working mode of the camera module 600 can be switched.

[0419] As mentioned above, the filters 300 / 400 provided in this application have two modes: visible light mode and infrared light mode. In visible light mode, the filters 300 / 400 can transmit visible light, and in infrared light mode, the filters 300 / 400 can transmit infrared light. Optionally, in infrared light mode, the filters 300 / 400 can also transmit visible light. Correspondingly, the camera module 600 has two operating modes: a first operating mode and a second operating mode. These are described in detail below.

[0420] In some embodiments, when the filters 300 / 400 are in visible light mode, since the filters 300 / 400 transmit visible light but not infrared light, the camera module 600 can be in visible light imaging mode, i.e., the first operating mode is visible light imaging mode. When the filters 300 / 400 are in infrared light mode, since the filters 300 / 400 transmit infrared light, the camera module 600 can be in infrared light imaging mode, i.e., the second operating mode is infrared light imaging mode. In practical applications, the operating band of the filters 300 can be switched according to the usage scenario, thereby switching the operating mode of the camera module 600 to improve the user experience in different usage scenarios.

[0421] As an example, when the camera module 600 is used for taking pictures, the filters 300 / 400 can be in visible light mode, and correspondingly, the camera module 600 is in a first operating mode. When the camera module 600 is used for unlocking, the filters 300 / 400 can be in infrared light mode, and correspondingly, the camera module 600 is in a second operating mode.

[0422] For example, an electronic device can determine the usage scenario by detecting the activation mode of the camera module 600. For instance, when the camera module 600 is activated in response to the opening of a camera interface (such as the shooting interface of a camera application or a shooting interface in a non-camera application), it can be determined that the camera module 600 is in a shooting scenario. Therefore, the filters 300 / 400 can be controlled to be in visible light mode, thus putting the camera module 600 into a first operating mode. When the camera module 600 is activated in response to the detection result of a proximity sensor or the clicking of an unlock control, it can be determined that the camera module 600 is in an unlocking scenario (such as unlocking a phone, unlocking an application, or payment verification). Therefore, the filters 300 / 400 can be controlled to be in infrared light mode, thus putting the camera module 600 into a second operating mode.

[0423] In this implementation, when a user wants to take a photo using the camera module, the filters 300 / 400 do not allow infrared light to pass through, preventing infrared light from entering and causing color distortion in the image, thus improving image quality. When a user wants to unlock the camera module, the filters 300 / 400 allow infrared light to pass through for unlocking, reducing unlocking time. Furthermore, the infrared reflection characteristics of skin enable more accurate facial recognition.

[0424] As another example, when the camera module 600 is in a bright light environment, the filters 300 / 400 can be in visible light mode, and correspondingly, the camera module 600 is in a first operating mode. When the camera module 600 is in a dark light environment, the filters 300 / 400 can be in infrared light mode, and correspondingly, the camera module 600 is in a second operating mode.

[0425] For example, an electronic device can determine the ambient light intensity by detecting the light intensity using a light sensor and / or sensing the light intensity signal using an image sensor. For instance, when the light intensity detected by the light sensor and / or the light intensity signal sensed by the image sensor is greater than or equal to a preset threshold, it can be determined that the camera module 600 is in a strong light environment, and thus the filters 300 / 400 can be controlled to be in visible light mode, thereby putting the camera module 600 into a first operating mode. When the light intensity detected by the light sensor and / or the light intensity signal sensed by the image sensor is less than the preset threshold, it can be determined that the camera module 600 is in a low light environment, and thus the filters 300 / 400 can be controlled to be in infrared light mode, thereby putting the camera module 600 into a second operating mode.

[0426] For example, when the camera module 600 is in a bright light environment, the filters 300 / 400 allow visible light to pass through but not infrared light, allowing the camera module 600 to take pictures and unlock based on visible light. When the camera module 600 is in a low light environment, the filters 300 / 400 allow both visible and infrared light to pass through, allowing the camera module 600 to take pictures based on visible light and unlock based on infrared light.

[0427] In this implementation, under strong light conditions, filters 300 / 400 do not transmit infrared light, preventing infrared light from entering the image and causing color distortion, thus improving image quality. Simultaneously, using visible light for unlocking in strong light conditions ensures timely unlocking. In low light conditions, the camera module 600 actively emits infrared light, which filters 300 / 400 can transmit for unlocking, reducing unlocking time. When the camera module 600 is used for taking photos, the intensity of infrared light in the ambient light is low, having minimal impact on the captured image quality.

[0428] As another example, when the camera module 600 is in a low-light environment and used for unlocking scenes, the filters 300 / 400 can be in infrared light mode, and correspondingly, the camera module 600 is in a second operating mode. When the camera module 600 is in a bright light environment or used for taking pictures, the filters 300 / 400 can be in visible light mode, and correspondingly, the camera module 600 is in a first operating mode.

[0429] In this method, when unlocking in low-light environments, filters 300 / 400 can transmit infrared light for unlocking, which can shorten unlocking time and improve unlocking performance. In other scenarios, filters 300 / 400 do not transmit infrared light, thus avoiding the impact of infrared light on the quality of the captured image. In addition, in bright light environments, visible light is used for unlocking, and the electronic device does not need to actively emit infrared light, which can save power consumption.

[0430] In some embodiments, the camera module 600 may include a processing module for controlling the operating state of the switching filter (i.e., changing the filtering wavelength range of the filter, or changing the passband of the filter). In other embodiments, the processing module may not be integrated into the camera module 600, but may be controlled as a separate module.

[0431] In summary, the filter provided in this application embodiment can switch filter modes under preset conditions, thereby enabling the camera module 600 to switch operating modes. Specifically, when the first preset condition is met, the filter provided in this application is in visible light mode, wherein the infrared passband of the filter is closed, and the camera module is in the first operating mode. When the second preset condition is met, the filter provided in this application is in infrared light mode, wherein the infrared passband of the filter is open, and the camera module is in the second operating mode.

[0432] For example, the first preset condition includes: detecting that the display screen shows the shooting interface (i.e., the camera function is turned on, such as when the user clicks the camera app icon or clicks the shooting control in the app to open the shooting interface). The second preset condition includes at least one of the following: the detection result of the proximity sensor is within the first preset range; or the user clicks the control used for unlocking is detected.

[0433] For example, the first preset condition includes: the light intensity in the environment is greater than or equal to a preset threshold. The second preset condition includes: the light intensity in the environment is less than a preset threshold.

[0434] For example, the first preset condition includes at least one of the following: the ambient light intensity is greater than or equal to a preset threshold; the display screen shows the shooting interface. The second preset condition includes: the ambient light intensity is less than a preset threshold, and the detection result of the distance sensor is within the first preset range.

[0435] For ease of understanding, a filter provided in this application is described below with reference to specific, rather than limiting, examples. The filter includes the aforementioned field-chromatic thin film 320 and the aforementioned dual-pass film 330.

[0436] For example, the film layer stacking structure of the field-chromic thin film 320 is shown in Table 1 below.

[0437] Table 1

[0438] In Table 1, SiO₂ is the chemical formula for silicon dioxide, a low-refractive-index material. SBS is the chemical formula for antimony trisulfide, a high-refractive-index material. ITO is the chemical formula for indium tin oxide, a transparent conductive material.

[0439] It should be noted that the ITO layer in Table 1 does not affect the structure of alternating high and low refractive index stacking. Films 27 and 29 can be considered as a low refractive index layer, except that a transparent conductive layer is set in it.

[0440] For example, the film stacking structure of the dual-pass film 330 is shown in Table 2 below.

[0441] Table 2

[0442] In Table 2, SiO2 is the chemical formula for silicon dioxide, which is a low refractive index material. TiO2 is the chemical formula for titanium dioxide, which is a high refractive index material.

[0443] For example, the material of the switchable layer 324 in the field-chromic film 320 can be antimony trisulfide Sb₂S₃ (or denoted as SBS). The refractive index of Sb₂S₃ can be 3.3 in the low refractive index state and 3.8 in the high refractive index state.

[0444] For example, Figure 30(a) shows a schematic diagram of the transmittance curves of the field-chromic film shown in Table 1 and the dual-pass film shown in Table 2. As can be seen from the figure, in visible light mode, the combined two films allow transmission of visible light but not infrared light. In infrared mode, the combined two films allow transmission of both visible light and infrared light with a center wavelength of 850 nm.

[0445] For example, Figure 30(b) shows a schematic diagram of the transmittance curves of the field-chromic film shown in Table 1 above. As can be seen from the figure, in visible light mode, the field-chromic film can transmit visible light wavelengths below 850 nm. In infrared mode, the field-chromic film can transmit both visible light wavelengths and infrared light wavelengths with a center wavelength of 850 nm.

[0446] To accommodate both visible light and infrared imaging, this application also provides a camera module. Figure 31 shows a schematic architecture diagram of the camera module provided in an embodiment of this application. The camera module 700 shown in Figure 31 can be a specific example of the aforementioned camera module 600.

[0447] As shown in Figure 31, the camera module 700 includes a lens assembly 710, a filter 720, and an image sensor 730. The filter 720 can be the aforementioned filter 300 or 400, or the aforementioned filter group composed of the first filter 510 and the second filter 520. The image sensor 730 can be an example of the aforementioned image sensor 242. The lens assembly 710, from the object side to the image side, includes, in sequence: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5. The relevant parameters of the camera module 700 are described below with reference to Tables 3 to 5.

[0448] Table 3 below shows the basic optical parameters of the camera module 700.

[0449] Table 3

[0450] Table 4 below shows the specific parameters of each optical element in the camera module 700, where the units for radius of curvature and thickness are millimeters (mm).

[0451] Table 4

[0452] In Table 3, the meanings of each symbol are as follows:

[0453] Surface 2 and surface 3 are the object-side surface and image-side surface of the first lens L1, respectively;

[0454] Surface 4 and surface 5 are the object-side surface and image-side surface of the second lens L2, respectively;

[0455] Surface 6 and surface 7 are the object-side surface and image-side surface of the third lens L3, respectively;

[0456] Surface 8 and surface 9 are the object-side surface and image-side surface of the fourth lens L4, respectively;

[0457] Surface 10 and surface 11 are the object-side surface and image-side surface of the fifth lens L5, respectively;

[0458] Surface 12 and surface 13 are the object-side surface and image-side surface of filter 720, respectively;

[0459] R: The radius of curvature of the optical surface. A positive value indicates that the optical surface bulges towards the object side near the optical axis, and a negative value indicates that the optical surface bulges towards the image side near the optical axis. When the optical surface is a plane, the value of R is infinite (infinity, inf).

[0460] T: The on-axis thickness of an optical element (such as a lens, aperture, filter, etc.) or the on-axis distance between optical elements. For example, the thickness value corresponding to the object side of an optical element is the on-axis thickness of that optical element, and the thickness value corresponding to the image side of an optical element is the on-axis distance between that optical element and the next optical element, specifically the on-axis distance between the image side of that optical element and the object side of the next optical element.

[0461] In some embodiments, the even-order aspherical surface shape z in the camera module 700 can be expressed using, but is not limited to, the following aspherical curve formula:

[0462] Where z is the aspherical surface's sag, specifically the distance sag from the vertex of the aspherical surface at a height of r along the optical axis; r is the radial coordinate of the aspherical surface; c is the paraxial curvature of the aspherical surface, equal to the reciprocal of its radius; k is the conic coefficient; A i Let A2, A4, A6, A8, ... be the aspherical coefficients of order i. 、 A 30 These represent the aspheric coefficients of the 2nd, 4th, 6th, 8th, ..., 30th orders, respectively.

[0463] As shown in Table 5 below, the aspherical coefficients corresponding to the surfaces of each optical element of the camera module 700 are all 0, where the conic coefficient k is 0, and the aspherical coefficients of the 18th, 20th, 22nd, 24th, 26th, 28th and 30th orders are also 0.

[0464] Table 5

[0465] It should be noted that the aspheric coefficients in Table 5 are expressed in scientific notation, for example, 5.4736E-002 = 5.4736 × 10 -2 1.1302E+000=1.1302×10 0 .

[0466] In summary, this application utilizes field-chromic materials to achieve a switching mechanism between visible and infrared light, thereby enabling the entire imaging system to switch between visible and infrared imaging. The imaging system comprises a switchable operating wavelength filter, a lens compatible with both visible and infrared imaging, an image sensor, and corresponding structural components. The switchable operating wavelength filter can change the refractive index of the color-changing material under external excitation, achieving a switching of the resonant wavelength, and thus switching the infrared light transmittance on or off. In visible light mode, infrared light is reflected or absorbed; in infrared mode, infrared light can pass through normally.

[0467] In this way, by using a single switchable filter, the functions that originally required two separate modules can be achieved using only a single image sensor and occupying only the space required by a single imaging module, thus saving module space and cost.

[0468] This application also provides an electronic device, including an image processor and a camera module described in the foregoing embodiments. The image processor is communicatively connected to the camera module and is used to receive and process images acquired by the camera module.

[0469] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A filter, characterized in that, This includes a substrate, a field-sensitive film, and a double-pass film stacked together; The field-chromic film includes a field-chromic material, which has a first refractive index under the action of a first electrical signal, so that the transmission band of the field-chromic film includes a first visible light band. The field-chromic material has a second refractive index under the action of a second electrical signal, so that the transmission band of the field-chromic film includes a first infrared light band. The first refractive index is less than the second refractive index. The transmission bands of the dual-pass film are a second visible light band and a second infrared light band, wherein the second visible light band at least partially overlaps with the first visible light band, the second infrared light band at least partially overlaps with the first infrared light band, and the second infrared light band does not overlap with the transmission band of the field-chromic film under the first electrical signal.

2. The filter according to claim 1, characterized in that, The minimum wavelength value of the field-chromic film in the transmission band under the first electrical signal is less than or equal to the minimum wavelength value of the field-chromic film in the transmission band under the second electrical signal. The maximum wavelength value of the field-chromic film in the transmission band under the first electrical signal is less than the maximum wavelength value of the field-chromic film in the transmission band under the second electrical signal.

3. The filter according to claim 1 or 2, characterized in that, The transmission band of the field-chromic film under the first electrical signal is obtained by shifting the transmission band of the field-chromic film under the second electrical signal towards the shortwave direction.

4. The filter according to any one of claims 1 to 3, characterized in that, The difference between the second refractive index and the first refractive index is greater than or equal to 0.1 and less than or equal to 4.

5. The filter according to any one of claims 1 to 4, characterized in that, The field-chromic film also includes a third visible light band in the transmission band under the second electrical signal, and the third visible light band at least partially overlaps with the second visible light band.

6. The filter according to any one of claims 1 to 5, characterized in that, The field-chromic film also includes a third infrared light band in the transmission band under the first electrical signal, and the third infrared light band does not overlap with the second infrared light band.

7. The filter according to any one of claims 1 to 6, characterized in that, The field-chromatic thin film includes at least three light-transmitting layers and at least one transparent conductive layer stacked together, wherein any two adjacent light-transmitting layers among the at least three light-transmitting layers have different refractive indices. The light-transmitting layer between two of the at least three light-transmitting layers is the intermediate light-transmitting layer. The intermediate light-transmitting layer has two adjacent light-transmitting layers distributed on opposite sides. The refractive indices of the two adjacent light-transmitting layers are both greater than the refractive index of the intermediate light-transmitting layer, or the refractive indices of the two adjacent light-transmitting layers are both less than the refractive index of the intermediate light-transmitting layer. Wherein, at least a portion of the at least three light-transmitting layers includes the field-induced color-changing material.

8. The filter according to claim 7, characterized in that, The refractive index of the light-transmitting layer furthest from the substrate among the at least three light-transmitting layers is greater than the refractive index of its adjacent light-transmitting layer; and / or The refractive index of the light-transmitting layer closest to the substrate among the at least three light-transmitting layers is greater than the refractive index of the light-transmitting layer adjacent to it.

9. The filter according to claim 7 or 8, characterized in that, The field-chromic film includes a transparent conductive layer, and the field-chromic material is a thermochromic material; or The field-chromic film includes two transparent conductive layers, and the field-chromic material is located between the two transparent conductive layers. The field-chromic material is an electrochromic material.

10. The filter according to claim 9, characterized in that, When the field-chromatic material is a thermochromic material, the field-chromatic material includes at least one of the following: vanadium dioxide, antimony trisulfide, germanium-antimony-tellurium alloy, and antimony selenide. When the field-chromatic material is an electrochromic material, the field-chromatic material includes at least one of the following: nickel oxide, tungsten trioxide, vanadium pentoxide, and liquid crystal.

11. The filter according to any one of claims 7 to 10, characterized in that, The field-chromatic thin film further includes an anti-reflective layer disposed on at least one side surface of the transparent conductive layer in the thickness direction.

12. The filter according to any one of claims 1 to 11, characterized in that, The field-chromic film and the dual-pass film are disposed on both sides of the substrate in the thickness direction; or The field-sensitive color-changing film and the dual-pass film are disposed on the same side of the substrate in the thickness direction.

13. A camera module, characterized in that, include: The image sensor comprises a lens, an image sensor, and a filter as described in any one of claims 1 to 12, wherein the lens is used to project an imaging beam from a subject onto the image sensor, and the filter is disposed in the optical path to filter the imaging beam.

14. The camera module according to claim 13, characterized in that, The filter is disposed between the lens and the image sensor, or on the side of the lens away from the image sensor, or inside the lens.

15. The camera module according to claim 13 or 14, characterized in that, The camera module has a first working mode and a second working mode. In the first working mode, the filter is subjected to the first electrical signal, and in the second working mode, the filter is subjected to the second electrical signal.

16. The camera module according to claim 15, characterized in that, The first working mode is used for taking photos, and the second working mode is used for face unlock; or, The first working mode is used for taking photos and face unlocking in bright light environments, while the second working mode is used for face unlocking in low light environments.

17. The camera module according to any one of claims 13 to 16, characterized in that, The camera module also includes an infrared emitting module, which is used to emit a fourth infrared light band. The fourth infrared light band at least partially overlaps with the second infrared light band and at least partially overlaps with the first infrared light band.

18. A camera module, characterized in that, include: The system comprises a lens, an image sensor, a first filter, and a second filter. The lens projects an imaging beam from a subject onto the image sensor. The first filter and the second filter are disposed in the optical path to filter the imaging beam. The first filter includes a first substrate and a field-chromic film stacked together. The field-chromic film includes a field-chromic material. The field-chromic material has a first refractive index under the action of a first electrical signal, so that the transmission band of the field-chromic film includes a first visible light band. The field-chromic material has a second refractive index under the action of a second electrical signal, so that the transmission band of the field-chromic film includes a first infrared light band. The first refractive index is less than the second refractive index. The second filter includes a second substrate and a double-pass film stacked together. The transmission bands of the double-pass film are a second visible light band and a second infrared light band. The second visible light band at least partially overlaps with the first visible light band, and the second infrared light band at least partially overlaps with the first infrared light band. The second infrared light band does not overlap with the transmission band of the field-chromic film under the first electrical signal.

19. The camera module according to claim 18, characterized in that, The minimum wavelength value of the field-chromic film in the transmission band under the first electrical signal is less than or equal to the minimum wavelength value of the field-chromic film in the transmission band under the second electrical signal. The maximum wavelength value of the field-chromic film in the transmission band under the first electrical signal is less than the maximum wavelength value of the field-chromic film in the transmission band under the second electrical signal.

20. The camera module according to claim 18 or 19, characterized in that, The transmission band of the field-chromic film under the first electrical signal is obtained by shifting the transmission band of the field-chromic film under the second electrical signal towards the shortwave direction.

21. The camera module according to any one of claims 18 to 20, characterized in that, The difference between the second refractive index and the first refractive index is greater than or equal to 0.1 and less than or equal to 4.

22. The camera module according to any one of claims 18 to 21, characterized in that, The field-chromic film also includes a third visible light band in the transmission band under the second electrical signal, and the third visible light band at least partially overlaps with the second visible light band.

23. The camera module according to any one of claims 18 to 22, characterized in that, The field-chromic film also includes a third infrared light band in the transmission band under the first electrical signal, and the third infrared light band does not overlap with the second infrared light band.

24. The camera module according to any one of claims 18 to 23, characterized in that, The field-chromatic thin film includes at least three light-transmitting layers and at least one transparent conductive layer stacked together, wherein any two adjacent light-transmitting layers among the at least three light-transmitting layers have different refractive indices. The light-transmitting layer between two of the at least three light-transmitting layers is the intermediate light-transmitting layer. The intermediate light-transmitting layer has two adjacent light-transmitting layers distributed on opposite sides. The refractive indices of the two adjacent light-transmitting layers are both greater than the refractive index of the intermediate light-transmitting layer, or the refractive indices of the two adjacent light-transmitting layers are both less than the refractive index of the intermediate light-transmitting layer. The field-chromic material is included in at least a portion of the at least three light-transmitting layers.

25. The camera module according to claim 24, characterized in that, The refractive index of the light-transmitting layer furthest from the substrate among the at least three light-transmitting layers is greater than the refractive index of its adjacent light-transmitting layer; and / or The refractive index of the light-transmitting layer closest to the substrate among the at least three light-transmitting layers is greater than the refractive index of the light-transmitting layer adjacent to it.

26. The camera module according to claim 24 or 25, characterized in that, The field-chromic film includes a transparent conductive layer, and the field-chromic material is a thermochromic material; or The field-chromic film includes two transparent conductive layers, and the field-chromic material is located between the two transparent conductive layers. The field-chromic material is an electrochromic material.

27. The camera module according to claim 26, characterized in that, When the field-chromatic material is a thermochromic material, the field-chromatic material includes at least one of the following: vanadium dioxide, antimony trisulfide, germanium-antimony-tellurium alloy, and antimony selenide. When the field-chromatic material is an electrochromic material, the field-chromatic material includes at least one of the following: nickel oxide, tungsten trioxide, vanadium pentoxide, and liquid crystal.

28. The camera module according to any one of claims 24 to 27, characterized in that, The field-chromatic thin film further includes an anti-reflective layer disposed on at least one side surface of the transparent conductive layer in the thickness direction.

29. The camera module according to any one of claims 18 to 28, characterized in that, The first filter or the second filter is disposed between the lens and the image sensor, or disposed on the side of the lens away from the image sensor, or disposed in the lens.

30. The camera module according to any one of claims 18 to 29, characterized in that, The camera module has a first working mode and a second working mode. In the first working mode, the first filter is subjected to the first electrical signal, and in the second working mode, the first filter is subjected to the second electrical signal.

31. The camera module according to claim 30, characterized in that, The first working mode is used for taking photos, and the second working mode is used for face unlock; or, The first working mode is used for taking photos and face unlocking in bright light environments, while the second working mode is used for face unlocking in low light environments.

32. The camera module according to any one of claims 18 to 31, characterized in that, The camera module also includes an infrared emitting module, which is used to emit a fourth infrared light band. The fourth infrared light band at least partially overlaps with the second infrared light band and at least partially overlaps with the first infrared light band.

33. An electronic device, characterized in that, The system includes an image processor and a camera module as described in any one of claims 13 to 32, wherein the image processor is communicatively connected to the camera module and is used to receive and process images acquired by the camera module.

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