Reflective film, folding element, camera module, and electronic device

Abstract

A reflective film (60), a folding element (11), a camera module (10), and an electronic device (100). The folding element (11) comprises a prism (50) and multiple reflective films (60). The prism (50) has multiple non-total internal reflection surfaces, and one reflective film (60) is arranged on each non-total internal reflection surface. Any two of the reflective films (60) have the same number of film stacks; and along the path of light passing through the multiple non-total internal reflection surfaces, among two adjacent reflective films (60), an ith film stack from the prism (50) to the air in one reflective film (60) is used for reflecting light at a central wavelength of λ1, and an nth film stack from the prism (50) to the air in the other reflective film (60) is used for reflecting light at the same central wavelength of λ2, wherein λ1 is the same as λ2, and the ith film stack and the nth film stack have the same optical thickness. The reflectance of each film stack to the reflected light at a central wavelength is greater than or equal to 80%, and the refractive indexes of two adjacent film layers in each film stack are different. Use of the folding element (11) can reduce the size of the camera module (10).

Description

Reflective films, folding elements, camera modules and electronic devices

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 1, 2024, with application number 202410239066.X and application name “Reflective film, folding element, camera module and electronic device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to the field of optical imaging technology, and in particular to a reflective film, a folding element, a camera module, and an electronic device. Background Art

[0003] Camera modules have become an indispensable functional component in electronic products such as mobile phones, tablets, laptops, and wearable devices. As electronic devices become thinner and more multifunctional, the camera modules they use are also becoming increasingly smaller and thinner. With the quality and demand for photographic images increasingly comparable to those of SLR cameras, the size and functionality of camera modules have become key features of electronic devices. A camera module consists of a lens assembly and an image sensor. The lens assembly is typically composed of multiple lens elements arranged in sequence along the optical axis. Light passes through the lens assembly and is projected onto the image sensor for photoelectric conversion, which is then used for imaging. In related technologies, camera modules use a "periscope" design to achieve a long focal length to meet the needs of long-distance photography. However, the large size of periscope camera modules increases the difficulty of miniaturizing electronic devices. Summary of the Invention

[0004] The embodiments of the present application provide a reflective film, a folding element, a camera module, and an electronic device, which can reduce the volume of the camera module and reduce the difficulty of miniaturization of the electronic device.

[0005] In a first aspect, the present application provides a reflective film comprising a plurality of stacked film stacks. Adjacent film stacks have different optical thicknesses, are configured to reflect light of different central wavelengths, and each film stack has a reflectivity greater than or equal to 80% for the reflected light of the central wavelength. Each film stack comprises a plurality of stacked film layers, each of which has a different refractive index. This allows the reflective film to reflect light of different central wavelengths through different numbers of film stacks, thereby improving the reflectivity of the reflective film for light of different central wavelengths.

[0006] In one possible embodiment, the absolute value of the difference in refractive index between two adjacent film layers in at least one film stack is greater than or equal to 0.6. Thus, when the number of film layers is constant, the reflectivity of the film stack to reflected light can be further increased, thereby helping to improve the reflectivity of the reflective film to light.

[0007] In a possible embodiment, the reflectivity of each film stack to the reflected light of the central wavelength is greater than or equal to 98%, which can further increase the reflectivity of the reflecting film to light, thereby further improving the transmittance.

[0008] In one possible embodiment, the refractive index of each film layer of at least one film stack is greater than or equal to 1.6, thereby increasing the reflectivity of the film stack to reflected light.

[0009] In one possible embodiment, the refractive index of each film layer of at least one film stack is less than 1.6, thereby increasing the reflectivity of the film stack to reflected light.

[0010] In one possible embodiment, the refractive index of a portion of the film layers of at least one film stack is greater than or equal to 1.6, and the refractive index of another portion of the film layers is less than 0.6. In this way, the reflectivity of the film stack to the reflected light can be improved.

[0011] In one possible embodiment, the thickness of at least one film layer having a refractive index greater than or equal to 1.6 in the film stack is greater than or equal to 80 nm and less than or equal to 150 nm. In this way, when the number of film layers is constant, the reflectivity of the film stack can be further improved.

[0012] In one possible embodiment, the thickness of at least one film layer with a refractive index less than 1.6 in the film stack is greater than or equal to 100 nm and less than or equal to 180 nm. In this way, when the number of film layers is constant, the reflectivity of the film stack can be further improved.

[0013] In one possible embodiment, at least two film stacks include two film layers with different refractive indices, which can simplify the structure of the film stack and help reduce the difficulty of stacking the film stack.

[0014] In one possible embodiment, the optical thicknesses of any two film stacks are different, which can reduce the number of film stacks and help reduce the thickness of the reflective film.

[0015] In a possible implementation manner, the reflective film is a dielectric film.

[0016] In a possible implementation manner, the reflective film is a metal film.

[0017] In a possible implementation, the reflective film is a metal-dielectric film, which includes a metal layer and a dielectric layer formed by a plurality of film stacks.

[0018] In one possible embodiment, the reflectivity of each film stack to light of other central wavelengths other than the corresponding central wavelength is less than 80%.

[0019] In one possible embodiment, the reflectivity of each film stack to light of other central wavelengths other than the corresponding central wavelength is less than 50%.

[0020] The second aspect of the present application provides a deflection element, comprising a prism and a plurality of reflective films as described in any one of the first aspects. The prism has a plurality of non-total reflection surfaces for reflecting light, and a reflective film is provided on each non-total reflection surface. The number of film stacks of any two reflective films is the same, and along the path of light passing through the plurality of non-total reflection surfaces, in two adjacent reflective films, the i-th film stack from the prism to the air in one reflective film is used to reflect light with a central wavelength of λ1, and the n-th film stack from the prism to the air in the other reflective film is used to reflect light with the same central wavelength of λ2, λ1 is the same as λ2, and the optical thickness of the i-th film stack and the n-th film stack are the same. Wherein, i+n=m+1, i≤m, n≤m, i, n and m are all positive integers, and m is the number of film stacks of each reflective film.

[0021] By providing a reflective film on a non-total reflection surface that does not meet the total reflection conditions, total reflection can be generated at the non-total reflection surface, causing the prism to reflect light multiple times, thereby reducing the volume of the prism and, in turn, the volume of the deflecting element. In addition, by achieving total reflection through the reflective film, the total reflection angle of the prism can be decoupled from the total reflection angle, so that the prism at any angle can reflect light multiple times, thereby achieving high transmittance while also reducing the volume of the prism.

[0022] Furthermore, as light passes through multiple non-total reflection surfaces, adjacent reflective films complement each other, minimizing or eliminating the optical path difference for light of different central wavelengths across all non-total reflection surfaces. This improves transmittance while also improving or resolving chromatic dispersion. Complementary refers to the fact that the two adjacent reflective films have the same number of film stacks, the same composition of the film stacks, and that the order of the film stacks relative to the prism is opposite.

[0023] In a possible implementation, the prism has an even number of non-total reflection surfaces. In this way, the optical path difference of light with different central wavelengths after passing through all the non-total reflection surfaces is zero, which can solve the dispersion problem.

[0024] In a possible implementation, each reflective film is a dielectric film, so that the volume of the deflecting element can be further reduced while solving the dispersion problem and achieving high transmittance.

[0025] In a possible implementation, each reflective film is a metal film, so that the volume of the deflecting element can be further reduced while solving the dispersion problem and achieving high transmittance.

[0026] In one possible embodiment, the reflective film is a metal-dielectric film, comprising a metal layer and a dielectric layer positioned between the metal layer and the prism. This allows for prisms of any angle with an even or odd number of non-total reflective surfaces to resolve or improve dispersion issues and achieve high transmittance through the absorption properties of the metal layer.

[0027] A third aspect of the present application provides a camera module comprising an image sensor, a lens, and a deflecting element as described in any one of the second aspects. The lens and the image sensor are disposed on the same side of the deflecting element, or the lens and the image sensor are disposed on opposite sides of the deflecting element.

[0028] Since the deflecting element is composed of prisms and reflective films at arbitrary angles, the deflecting element has high transmittance and a small size, thereby reducing the size of the camera module and further reducing the difficulty of miniaturization of electronic devices.

[0029] A fourth aspect of the present application provides an electronic device, comprising a housing and a camera module as in the third aspect, wherein the camera module is mounted on the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1 is a cross-sectional view of a camera module in the related art;

[0031] FIG2A is a schematic diagram of a prism reflecting light through an odd number of reflecting surfaces in the related art;

[0032] FIG2B is a schematic diagram of a prism in the related art reflecting light through an even number of reflecting surfaces;

[0033] FIG3 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application;

[0034] FIG4 is a schematic structural diagram of a camera module provided in an embodiment of the present application;

[0035] FIG5 is a schematic structural diagram of another camera module provided in an embodiment of the present application;

[0036] FIG6 is a cross-sectional schematic diagram of a reflective film provided in an embodiment of the present application;

[0037] FIG7 is a schematic structural diagram of a deflection element provided in an embodiment of the present application;

[0038] FIG8 is a schematic structural diagram of another deflection element provided in an embodiment of the present application;

[0039] FIG9 is a graph showing the reflectivity of the first reflective film at different centers in FIG7 ;

[0040] Figure 10 shows the reflectivity curves of the second reflective film for different central wavelengths;

[0041] FIG11 is a schematic cross-sectional view of another reflective film provided in an embodiment of the present application.

[0042] Explanation of the accompanying drawings: 100, electronic device; 10, camera module; 11, folding element; 12, lens; 13, image sensor; 20, housing; 30, horn; 40, data interface; 50, prism; 51, first non-total reflection surface; 52, second non-total reflection surface; 53, total reflection surface; 60, reflective film; 60A, first reflective film; 60B, second reflective film; 61, first film stack; 62, second film stack; 63, third film stack; 64, fourth film stack; 65, dielectric layer; 66, metal layer; c1, blue light; c2, green light; c3, yellow light; c4, red light. DETAILED DESCRIPTION

[0043] The terms used in the implementation section of this application are only used to explain the specific embodiments of this application and are not intended to limit this application.

[0044] To facilitate understanding, the relevant technical terms involved in the embodiments of this application are first explained and illustrated.

[0045] Dispersion refers to the phenomenon that complex light is decomposed into monochromatic light to form a spectrum.

[0046] Transmittance: The ratio of the radiant energy projected and transmitted through the object to the total radiant energy projected onto the object in the process of the incident light flux leaving from the illuminated surface or the incident surface of the medium to the other side is called the transmittance of the object.

[0047] The center wavelength refers to the wavelength corresponding to the center position of the spectral distribution curve. For example, the wavelength range of red light is 760-622nm, with a center wavelength of 660nm, or the wavelength range of green light is 577-492nm, with a center wavelength of 550nm, and so on.

[0048] Optical thickness: The geometric thickness of a medium multiplied by its refractive index is called optical thickness. Geometric thickness refers to the physical thickness or actual thickness of the medium.

[0049] Total internal reflection (TIR) ​​is an optical phenomenon. When light passes from a medium with a higher refractive index into a medium with a lower refractive index, if the angle of incidence is greater than a certain critical angle (the light is far from the normal), the refracted light will disappear and all the incident light will be reflected without entering the medium with a lower refractive index.

[0050] Group delay effect: It is mainly reflected in the different refractive indices corresponding to light of different frequencies, so the reflectivity and reflection depth of different lights are different under the same film system.

[0051] Optical path is a fundamental concept in the field of optics, which is defined as the product of the geometric distance of light propagation and the refractive index of the medium.

[0052] As the name suggests, optical path difference is the difference in the optical path lengths of two light beams.

[0053] 1 is a cross-sectional view of a camera module in the related art, FIG2A is a schematic diagram of a prism in the related art reflecting light through an odd number of reflection surfaces, and FIG2B is a schematic diagram of a prism in the related art reflecting light through an even number of reflection surfaces.

[0054] In related art, as shown in Figure 1, a periscope camera module 200 includes a prism 210, an image sensor 220, and a lens assembly 230. The lens assembly 230 is disposed between the prism 210 and the image sensor 220 and comprises multiple parallel lenses, achieving a long focal length design to meet the needs of long-range photography. However, the periscope camera module 200 is relatively large, which increases the difficulty of miniaturizing electronic devices.

[0055] To reduce the difficulty of miniaturizing electronic devices, in one embodiment, the volume of the periscope camera module 200 can be compressed through multiple reflections of the prism 210. The prism 210 has multiple reflective surfaces for reflecting light, and a total reflection film 240 is coated on the reflective surfaces that do not meet the total reflection conditions (as shown in FIG2A ). This allows the size of the prism 210 to be made smaller, thereby reducing the volume of the periscope camera module 200 and, in turn, reducing the difficulty of miniaturizing electronic devices.

[0056] As shown in FIG2A , the prism 210 has three reflective surfaces, including a total reflection surface d1, a first non-total reflection surface d2, and a second non-total reflection surface d3. Light meets the total reflection condition at the total reflection surface d1, and there is no need to coat the total reflection film 240 on the total reflection surface d1. Light does not meet the total reflection condition at the first non-total reflection surface d2 and the second non-total reflection surface d3, so the first non-total reflection surface d2 and the second non-total reflection surface d3 are both coated with a total reflection film 240, so that the light is totally reflected at the first non-total reflection surface d2 and the second non-total reflection surface d3. However, the total reflection film 240 is a dielectric film, and the dielectric film has a group delay effect, which causes light of different center wavelengths to be reflected at different depths of the total reflection film 240 (as shown by M1 and M2 in FIG2A ). As a result, the optical path lengths of light of different center wavelengths after passing through the total reflection film 240 are different, and thus, light of different center wavelengths has an optical path length difference after passing through the total reflection film 240. Therefore, after the light is reflected an odd number of times in the prism 210, there is an optical path difference between the lights of different central wavelengths leaving the prism 210, so that the lights of different central wavelengths leaving the prism 210 do not overlap, resulting in the emergence of a dispersion problem, causing one of the first non-total reflection surface d2 and the second non-total reflection surface d3 to form a red edge and the other to form a blue edge.

[0057] In another embodiment, as shown in FIG2B , the prism 210 has two reflective surfaces, namely a first non-total reflective surface d2 and a second non-total reflective surface d3. Light does not meet the total reflection condition at the first non-total reflective surface d2 and the second non-total reflective surface d3, so a total reflection film 240 (not shown in FIG2B ) is coated on both the first non-total reflective surface d2 and the second non-total reflective surface d3, so that the light is totally reflected at the first non-total reflective surface d2 and the second non-total reflective surface d3. The total reflection film 240 is a dielectric film, and light of different center wavelengths (as shown by M1 and M2 in FIG2B ) has an optical path difference at both reflective surfaces. As can be seen from FIG2B , when light of different center wavelengths leaving the prism 240 overlaps, no dispersion problem will occur. In this case, β=α, β=180°-3α=α, that is, α=45°. When α≠45°, β≠α, and light of different center wavelengths leaving the prism 240 does not overlap, resulting in dispersion problems. Therefore, when light is reflected an even number of times in the prism 210, if the angle of the prism 210 is not equal to 45°, a dispersion problem will occur.

[0058] In view of this, the embodiment of the present application provides a reflective film 60, a deflecting element 11, a camera module 10, and an electronic device 100. The deflecting element 11 includes a prism 50 and a reflective film 60. The prism 50 has multiple reflective surfaces. The reflective film 60 is plated on a non-total reflective surface among the multiple reflective surfaces, so that light is totally reflected at the non-total reflective surface, and the total reflective surface does not need to be plated with a reflective film 60. Along the path of light passing through all reflective surfaces, two adjacent reflective films 60 complement each other, which can make the prism 50 at any angle have high transmittance while also improving or solving the dispersion problem, reducing the volume of the camera module 10, and reducing the difficulty of miniaturization of the electronic device 100.

[0059] The electronic device 100 may include, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an ultra-mobile personal computer (UMPC), a handheld computer, a walkie-talkie, a netbook, a POS machine, a personal digital assistant (PDA), a wearable device, a virtual reality device, a vehicle-mounted device, and the like having a camera module 10 .

[0060] In the embodiment of the present application, the electronic device 100 is taken as a mobile phone as an example. The mobile phone can be a bar phone, or the mobile phone can also be a foldable phone. The following description is made by taking the electronic device 100 as a bar phone as an example.

[0061] FIG3 is a schematic structural diagram of an electronic device provided in an embodiment of the present application.

[0062] As shown in FIG3 , the electronic device 100 includes a display screen, a housing 20 and a camera module 10. The camera module 10 can be mounted on the housing 20 for taking photos. The display screen is mounted on the housing 20 for displaying text, images and other information.

[0063] The camera module 10 can be located on the front side (the side with the display screen) of the electronic device 100 for taking selfies or other photographs. Alternatively, as shown in FIG3 , the camera module 10 can also be located on the back side (the side facing away from the display screen) of the electronic device 100 for taking photographs of other objects, including selfies.

[0064] The number of the camera module 10 may be one, or the number of the camera module 10 may be multiple to meet different shooting requirements.

[0065] The electronic device 100 may further include other structural components. For example, as shown in FIG3 , the housing 20 of the electronic device 100 may further include a speaker 30 , which may be used to play audio, etc., of the electronic device 100. As shown in FIG3 , the housing 20 of the electronic device 100 may further include a data interface 40 , which may be used to power the electronic device 100 or to connect the electronic device 100 to headphones, external multimedia devices, and the like (such as an external camera or an external projection device).

[0066] Of course, in some other examples, the electronic device 100 may also include other structural components to complete the functions of the electronic device 100, such as sensors, processors, circuit boards, drive structures, etc., which are not limited in the embodiments of the present application.

[0067] FIG4 is a schematic structural diagram of a camera module provided in an embodiment of the present application.

[0068] As shown in Figure 4, the camera module 10 includes an image sensor 13, a lens 12 and a folding element 11. The folding element 11 is used to fold the optical axis so that the camera module 10 has a periscope structure. The folding element 11 is used to receive incident light. The incident light leaves the folding element 11 after multiple total reflections inside the folding element 11 and is received by the photosensitive surface (also referred to as the imaging surface) of the image sensor 13 to achieve imaging. By the folding element 11 reflecting the incident light multiple times, the volume of the folding element 11 can be further reduced, thereby achieving the purpose of achieving a smaller size of the camera module 10. At the same time, the folding element 11 has a high transmittance to the incident light and can improve or solve the dispersion problem.

[0069] The image sensor 13 may be a charge-coupled device (CCD), or a complementary metal oxide semiconductor (CMOS), or other devices capable of achieving a photoelectric conversion function.

[0070] The lens 12 may include one or more lenses, which is not specifically limited here.

[0071] It should be noted that the camera module 10 may also include other components. For example, the camera module 10 may also include a lens barrel, a filter, etc. The lens barrel is used to accommodate the image sensor 13, the filter or the lens 12, etc.

[0072] As shown in FIG. 4 , the lens 12 and the image sensor 13 are disposed on the same side of the deflecting element 11 . At this time, the deflecting element 11 is used to receive incident light emitted by the lens 12 and project the incident light onto the photosensitive surface of the image sensor 13 .

[0073] However, in some implementations, the image sensor 13 and the lens 12 may also be disposed on opposite sides of the deflecting element 11, as shown in Figure 5. Figure 5 is a schematic structural diagram of another camera module provided in an embodiment of the present application.

[0074] In the embodiment of the present application, the deflecting element 11 includes a prism 50 and multiple reflective films 60. The prism 50 has multiple non-total reflective surfaces for reflecting light, each of which is provided with a reflective film 60. Therefore, it can be seen that there is a one-to-one correspondence between the reflective films 60 and the non-total reflective surfaces. For example, as shown in FIG4 , there are two reflective films 60, corresponding to two non-total reflective surfaces. Each reflective film 60 is a dielectric film.

[0075] The specific structure of the prism 50 is not limited here. In some implementations, as shown in FIG4 , the prism 50 can be an isosceles trapezoid. In other implementations, as shown in FIG5 , the prism 50 can also be a parallelogram.

[0076] In some implementations, the prism 50 may have an even number of non-total reflective surfaces. For example, as shown in FIG4 , the prism 50 has two non-total reflective surfaces, and accordingly, the number of reflective films 60 is two. Of course, the number of non-total reflective surfaces may also be more than two, such as 4, 6, or 8.

[0077] In other implementations, the prism 50 may also have an odd number of non-total reflection surfaces. For example, the prism 50 may have three non-total reflection surfaces. Of course, the number of non-total reflection surfaces may also be more than three, for example, 5, 7, 9, etc.

[0078] The prism 50 further includes a total reflection surface 53. The number of total reflection surfaces 53 can be one or more. For example, as shown in FIG4 , there is one total reflection surface 53. Alternatively, as shown in FIG5 , there are two total reflection surfaces 53.

[0079] FIG6 is a schematic cross-sectional view of a reflective film provided in an embodiment of the present application.

[0080] As shown in Figure 6 , each reflective film 60 comprises a plurality of stacked film stacks. Adjacent film stacks have different optical thicknesses and are configured to reflect light of different central wavelengths. Each film stack has a reflectivity greater than or equal to 80% for the reflected light of the central wavelength. Each film stack comprises a plurality of stacked film layers, each with different refractive indices. This allows the reflective film 60 to reflect light of different central wavelengths through different numbers of film stacks, improving its reflectivity for light of different central wavelengths and achieving high optical efficiency. This also addresses or improves the dispersion problem of the prism 50.

[0081] 6 , the reflective film 60 includes four film stacks, which include a first film stack 61, a second film stack 62, a third film stack 63, and a fourth film stack 64. Of course, the number of film stacks may be more or less than four.

[0082] For example, as shown in Figure 6, the membrane stack may include six stacked membrane layers. Of course, the number of membrane layers in the membrane stack may be more or less than six.

[0083] In the embodiments of the present application, each film stack not only reflects light of its corresponding central wavelength, but also reflects light of other central wavelengths other than the corresponding central wavelength, and the reflectivity of light of other central wavelengths is less than 80%. For example, as shown in Figure 6, the first film stack 61 is configured to reflect blue light c1 with a central wavelength of 440nm, while also reflecting light of red light c4, green light c2, and yellow light c3. The reflectivity of the first film stack 61 for light of red light c4, green light c2, and yellow light c3 can be less than 50%.

[0084] The reflectivity of each film stack to light of other central wavelengths other than the corresponding central wavelength may include but is not limited to 20%, 30%, 40%, 50%, 55%, 60% or 70%, etc.

[0085] In some implementations, the reflectivity of each film stack for light at wavelengths other than the corresponding central wavelength can be less than 50%. This can improve the transmittance of each film stack for light at wavelengths other than the corresponding central wavelength, ensuring that the reflective film 60 fully reflects light at each central wavelength through different numbers of film stacks.

[0086] FIG7 is a schematic structural diagram of a deflection element provided in an embodiment of the present application, and FIG8 is a schematic structural diagram of another deflection element provided in an embodiment of the present application.

[0087] As shown in FIG7 , along the path of light passing through multiple non-total reflection surfaces (e.g., the solid lines with arrows in FIG7 or FIG8 ), two adjacent reflective films 60 complement each other, allowing the prism 50 to have high transmittance at any angle while improving or resolving the dispersion problem. Complementary refers to the two adjacent reflective films 60 having the same number of film stacks, the same film stack composition, and the opposite order of the film stacks relative to the prism 50. The same film stack composition can be understood as the same film layer type, arrangement, thickness, and number of film layers in two film stacks of the same optical thickness.

[0088] Specifically, any two reflective films 60 have the same number of film stacks. Along the path of light passing through multiple non-total reflection surfaces (such as the solid line with arrows in Figures 7 or 8), in two adjacent reflective films 60, the i-th film stack from the prism 50 to the air in one reflective film 50 is used to reflect light with a central wavelength of λ1, and the n-th film stack from the prism 50 to the air in the other reflective film 60 is used to reflect light with the same central wavelength of λ2, where λ1 is the same as λ2. In other words, the i-th film stack from the prism 50 to the air in one reflective film 60 and the n-th film stack from the prism 50 to the air in the other reflective film 60 are used to reflect light with the same central wavelength. The i-th film stack and the n-th film stack have the same optical thickness and the same structure as the n-th film stack. Wherein, i+n=m+1, i≤m, n≤m, i, n, and m are all positive integers, and m is the number of film stacks in each reflective film 60. Such an arrangement enables two adjacent reflective films 60 to complement each other, thereby allowing the prism 50 at any angle to have high transmittance while improving or solving the dispersion problem.

[0089] The following example describes the complementary characteristics of two adjacent reflective films 60:

[0090] Exemplarily, as shown in Figure 7, the prism 50 has two non-total reflection surfaces and one total reflection surface 53. Light enters the interior of the prism 50 through the total reflection surface 53, and then passes through the first non-total reflection surface 51, the total reflection surface 53 and the second non-total reflection surface 52 in sequence before leaving the prism 50 through the total reflection surface 53.

[0091] Continuing with FIG7 , along the path of light passing through all the non-total reflection surfaces in the prism 60, the first reflective film 60A and the second reflective film 60B are adjacent. The first reflective film 60A is disposed on the first non-total reflection surface 51. The first reflective film 60A includes four stacked film stacks. The first film stack a1 of the four film stacks is closest to the first non-total reflection surface 51, and the fourth film stack a4 of the four film stacks is the farthest from the first non-total reflection surface 51. The second reflective film 60B is disposed on the second non-total reflection surface 52. The second reflective film 60B includes four stacked film stacks. The first film stack b1 of the four film stacks is closest to the second non-total reflection surface 52, and the fourth film stack b4 of the four film stacks is the farthest from the second non-total reflection surface 52.

[0092] The first film stack a1 in the first reflective film 60A and the fourth film stack b4 in the second reflective film 60B are configured to reflect light of the same central wavelength. The second film stack a2 in the first reflective film 60A and the third film stack b3 in the second reflective film 60B are configured to reflect light of the same central wavelength. The third film stack a3 in the first reflective film 60A and the second film stack b2 in the second reflective film 60B are configured to reflect light of the same central wavelength. The fourth film stack a4 in the first reflective film 60A and the first film stack b1 in the second reflective film 60B are configured to reflect light of the same central wavelength. Therefore, the arrangement order of the film stacks in the first reflective film 60A and the second reflective film 60B is opposite.

[0093] The first film stack a1 in the first reflective film 60A and the fourth film stack b4 in the second reflective film 60B have the same optical thickness and structure. The second film stack a2 in the first reflective film 60A and the third film stack b3 in the second reflective film 60B have the same optical thickness and structure. The third film a3 in the first reflective film 60A and the second film stack b2 in the second reflective film 60B have the same optical thickness and structure. The fourth film stack a4 in the first reflective film 60A and the first film stack b1 in the second reflective film 60B have the same optical thickness and structure.

[0094] The following uses four lights with different central wavelengths, namely, blue light c1 , green light c2 , yellow light c3 and red light c4 , as examples to illustrate how two adjacent reflective films 60 reflect lights with different central wavelengths to achieve complementarity.

[0095] Continuing to refer to Figure 7, in the first reflective film 60A, the first film stack a1 is used to reflect blue light c1 with a central wavelength of 440nm, the second film stack a2 is used to reflect green light c2 with a central wavelength of 550nm, the third film stack a3 is used to reflect yellow light c3 with a central wavelength of 570nm, and the fourth film stack a4 is used to reflect red light c4 with a central wavelength of 660nm.

[0096] Continuing to refer to Figure 7, in the second reflective film 60B, the first film stack b1 is used to reflect red light c4 with a central wavelength of 660nm, the second film stack b2 is used to reflect yellow light c3 with a central wavelength of 570nm, the third film stack b3 is used to reflect green light c2 with a central wavelength of 550nm, and the fourth film stack b4 is used to reflect blue light c1 with a central wavelength of 440nm.

[0097] This shows that the i-th film stack in the first reflective film 60A and the n-th film stack in the second reflective film 60B reflect light of the same central wavelength, and the i-th and n-th film stacks have the same optical thickness. In this case, m = 4, i + n = 5, i ≤ 4, n ≤ 4, and i and n are positive integers. For example, when i = 1 and n = 4, the first film stack a1 in the first reflective film 60A and the fourth film stack b4 in the second reflective film 60B reflect blue light of the same central wavelength c1, and the first film stack a1 and the fourth film stack b4 have the same optical thickness.

[0098] FIG9 is a graph showing the reflectivity of the first reflective film 60A at different centers in FIG7 . In FIG9 , R represents reflectivity, g1 represents the reflectivity curve of the first reflective film 60A for blue light c1, g2 represents the reflectivity curve of the first reflective film 60A for green light c2, g3 represents the reflectivity curve of the first reflective film 60A for yellow light c3, and g4 represents the reflectivity curve of the first reflective film 60A for red light c4.

[0099] In the process of reflecting light of different central wavelengths by the first reflective film 60A in FIG7 , as shown in FIG9 , blue light c1 is reflected by the first film stack a1 in the first reflective film 60A, green light c2 is reflected by the first film stack a1 and the second film stack a2 in the first reflective film 60A, yellow light c3 is reflected by the first film stack a1, the second film stack a2, and the third film stack a3 in the first reflective film 60A, and red light c4 is reflected by the first film stack a1, the second film stack a2, the third film stack a3, and the fourth film stack a4 in the first reflective film 60A. Thus, it can be seen that light of different central wavelengths has an optical path difference after passing through the first reflective film 60A. For example, the optical path difference between red light c4 and green light c2 on the first reflective film 60A is the difference between the second film stack a2 and the third film stack a3.

[0100] It can be understood that the first film stack a1 of the first reflective film 60A can reflect light of various central wavelengths, and completely reflects the corresponding blue light c1 with a central wavelength of 440 nm, allowing light of various central wavelengths other than blue light c1 to reach the second film stack a2. Similarly, the second film stack a2 of the first reflective film 60A can reflect light of various central wavelengths other than blue light c1. The combined action of the first and second film stacks a1 and a2 completely reflects the corresponding green light c2 with a central wavelength of 550 nm. The third film stack a3 of the first reflective film 60A can reflect light of various central wavelengths other than blue light c1 and green light c2. The combined action of the first, second, and third film stacks a1, a2, and a3 completely reflects yellow light c3 with a central wavelength of 570 nm. The fourth film stack a4 of the first reflective film 60A reflects light of all central wavelengths except blue light c1, green light c2, and yellow light c3. The combined effects of the first, second, third, and fourth film stacks a1, a2, a3, and a4 reflect all red light c4, with a central wavelength of 660 nm. Therefore, light of different central wavelengths has an optical path difference after passing through the first reflective film 60A.

[0101] Figure 10 is a reflectivity curve diagram of the second reflective film for different central wavelengths. In Figure 10, R represents reflectivity, g1 represents the reflectivity curve of the second reflective film 60B for blue light c1, g2 represents the reflectivity curve of the second reflective film 60B for green light c2, g3 represents the reflectivity curve of the second reflective film 60B for yellow light c3, and g4 represents the reflectivity curve of the second reflective film 60B for red light c4.

[0102] In the process of reflecting light of different central wavelengths by the second reflective film 60B in FIG7 , as shown in FIG10 , blue light c1 is reflected by the first film stack b1, the second film stack b2, the third film stack b3, and the fourth film stack b4 of the second reflective film 60B; green light c2 is reflected by the first film stack b1, the second film stack b2, and the third film stack b3 of the second reflective film 60B; yellow light c3 is reflected by the first film stack b1 and the second film stack b2 of the second reflective film 60B; and red light c4 is reflected by the first film stack b1 of the second reflective film 60B. Thus, it can be seen that light of different central wavelengths has an optical path difference after passing through the second reflective film 60B. For example, the optical path difference between red light c4 and green light c2 is the difference between the second film stack b2 and the third film stack b3.

[0103] It can be understood that the first film stack of the second reflective film 60B can reflect light of various central wavelengths, and completely reflects the corresponding red light c4 with a central wavelength of 660 nm, allowing light of various central wavelengths other than red light c4 to reach the second film stack b2. Similarly, the second film stack b2 of the second reflective film 60B can reflect light of various central wavelengths other than red light c4. Under the combined action of the first and second film stacks b1 and b2, completely reflects the corresponding yellow light c3 with a central wavelength of 570 nm. The third film stack b3 of the second reflective film 60B can reflect light of various central wavelengths other than red light c4 and yellow light c3. Under the combined action of the first, second, and third film stacks b1, b2, and b3, completely reflects the green light c2 with a central wavelength of 550 nm. The fourth film stack b4 of the second reflective film 60B reflects light of all central wavelengths except red light c4, green light c2, and yellow light c3. The first, second, third, and fourth film stacks b1, b2, b3, and b4 all reflect blue light c1, with a central wavelength of 440 nm. This shows that light of different central wavelengths has an optical path difference after passing through the second reflective film 60B.

[0104] Combining Figures 9 and 10 , it can be seen that the optical path difference between red light c4 and green light c2 on the first reflective film 60A is the same as that between the second film stack a2 and the third film stack a3, and the optical path difference between red light c4 and green light c2 is the same as that between the second film stack b2 and the third film stack b3. The optical thickness of the second film stack a2 of the first reflective film 60A is the same as the optical thickness of the third film stack b3 of the second reflective film 60B, and the optical thickness of the second film stack a3 of the first reflective film 60A is the same as the optical thickness of the third film stack b2 of the second reflective film 60B. Therefore, the absolute value of the optical path difference between red light c4 and green light c2 on the first reflective film 60A is the same as that on the second reflective film 60B.

[0105] As shown in FIG7 , the film stacks of the first reflective film 60A and the second reflective film 60B are arranged in opposite order, resulting in a negative optical path difference between the red light c4 and the green light c2 on the second reflective film 60B. Consequently, the sum of the optical path differences between the red light c4 and the green light c2 at the first reflective film 60A and the second reflective film 60B is zero. Therefore, the optical path length of light of any central wavelength passing through two adjacent reflective films 60 is the same, and the optical path difference between any two central wavelengths passing through two adjacent reflective films 60 is the same. Furthermore, the optical path difference between any two central wavelengths passing through two adjacent reflective films 60 is zero. This ensures that light of different central wavelengths will not be deflected when passing through two adjacent reflective films 60, and thus will not experience dispersion.

[0106] It can be understood that the sum of the optical path difference between the red light c4 and the green light c2 on the first reflective film 60A and the optical path difference between the red light c4 and the green light c2 on the second reflective film 60B = A + (-B). Here, A = B, where A is the optical path difference between the red light c4 and the green light c2 on the first reflective film 60A, and B is the optical path difference between the red light c4 and the green light c2 on the second reflective film 60B. Because the film stacks in the first reflective film and the second reflective film 60B are arranged in opposite orders, the optical path difference between the red light c4 and the green light c2 passing through one of the two adjacent reflective films 60 is positive, and the optical path difference through the other reflective film 60 is negative. Therefore, A has a positive sign and B has a negative sign, or A has a negative sign and B has a positive sign.

[0107] When the number of non-total reflection surfaces is even, the sum of the optical path differences between any two central wavelengths of light after passing through the reflective films 60 on all non-total reflection surfaces is zero, effectively resolving the dispersion issue. Furthermore, the reflectivity of each film stack for light of the corresponding central wavelength is greater than 80%, resulting in a high reflectivity of the reflective films 60, which improves the transmittance of the prism 50. Furthermore, the angle of the prism 50 is decoupled from the dispersion issue, allowing the prism 50 to be positioned at any angle.

[0108] When the number of non-total reflection surfaces is odd, the sum of the optical path differences between any two central wavelengths of light after passing through the reflective films 60 on all non-total reflection surfaces is reduced, effectively improving dispersion. Furthermore, the reflectivity of each film stack for light of the corresponding central wavelength is greater than 80%, resulting in a high reflectivity of the reflective films 60, which improves the transmittance of the prism 50. Furthermore, the angle of the prism 50 is decoupled from the dispersion issue, allowing the prism 50 to be positioned at any angle.

[0109] It should be noted that the positions of the first reflective film 60A and the second reflective film 60B in Figure 7 can also be interchanged, which can also solve or improve the dispersion problem and achieve the same effect. Specifically, the first reflective film 60A can also be set on the second non-total reflection surface 52, and the second reflective film 60B can be set on the first non-total reflection surface 51. The first film stack a1 in the first reflective film 60A is closest to the second non-total reflection surface 52, and the fourth film stack a4 in the first reflective film 60A is farthest from the second non-total reflection surface 52. The first film stack b1 in the second reflective film 60B is closest to the first non-total reflection surface 51, and the fourth film stack b4 in the second reflective film 60B is farthest from the first non-total reflection surface 51.

[0110] When the first reflective film 60A is disposed on the second non-total reflection surface 52, the first film stack a1 of the first reflective film 60A reflects red light c4 with a central wavelength of 660 nm, the second film stack a2 reflects yellow light c3 with a central wavelength of 570 nm, the third film stack a3 reflects green light c2 with a central wavelength of 550 nm, and the fourth film stack a4 reflects blue light c1 with a central wavelength of 440 nm. In this case, the reflectivity curves of the first reflective film 60A for light of various central wavelengths are the same as those in FIG10 .

[0111] When the second reflective film 60B is disposed on the first non-total reflection surface 51, the first film stack b1 of the second reflective film 60B reflects blue light c1 with a central wavelength of 440 nm, the second film stack b2 reflects green light c2 with a central wavelength of 550 nm, the third film stack b3 reflects yellow light c3 with a central wavelength of 570 nm, and the fourth film stack b4 reflects red light c4 with a central wavelength of 660 nm. In this case, the reflectivity curves of the second reflective film 60B for light of various central wavelengths are the same as those in FIG9 .

[0112] In some possible implementations, the optical thicknesses of any two film stacks are different. For example, as shown in FIG6 , the optical thicknesses of the four film stacks in the reflective film 60 are all different. This can reduce the number of film stacks and help reduce the thickness of the reflective film 60.

[0113] It should be noted that, in addition to the different optical thicknesses of any two film stacks in the reflective film 60, in some implementations, the optical thicknesses of some film stacks in the reflective film 60 may be the same, while the optical thicknesses of another part of the film stacks may be different.

[0114] In some possible implementations, the reflectivity of each film stack to the reflected light of the central wavelength is greater than or equal to 98%, which can further increase the reflectivity of the reflection film 60 to light, thereby further improving the transmittance of the deflection element 11.

[0115] Exemplarily, as shown in FIG6 , the reflectivity of each of the four film stacks of the reflective film 60 to the reflected light of the central wavelength is greater than or equal to 98%.

[0116] It should be noted that, in addition to setting the reflectivity of each film stack in the reflective film 60 to be greater than or equal to 98% for the reflected light at the center wavelength, it is also possible to set the reflectivity of some film stacks in the reflective film 60 to be greater than or equal to 98% for the reflected light at the center wavelength, and set the reflectivity of other film stacks in the reflective film 60 to be greater than 80% and less than 98% for the reflected light at the center wavelength. For example, the reflective film 60 may include four film stacks, three of which have a reflectivity of greater than or equal to 98% for the reflected light at the center wavelength, and the remaining film stack has a reflectivity of greater than 80% and less than 98% for the reflected light at the center wavelength.

[0117] In some possible implementations, at least two film stacks of the reflective film 60 have the same number of film layers. For example, as shown in FIG6 , there are four film stacks, each consisting of six film layers. However, the number of film stacks having the same number of film layers may be less than four. For example, three of the four film stacks may consist of six film layers, and the remaining film stack may consist of five film layers.

[0118] In other possible implementations, the number of film layers in any two film stacks in the reflective film 60 may be different. For example, the reflective film 60 includes four film stacks, the first film stack may be composed of two film layers, the second film stack may be composed of three film layers, the third film stack may be composed of four film layers, and the fourth film stack may be composed of five film layers.

[0119] In some possible implementations, the number of film layers in at least one film stack can be greater than or equal to 2 and less than or equal to 50. For example, as shown in FIG6 , the number of film layers in each film stack is greater than 2 and less than 20. This helps reduce the physical thickness of the film stack while achieving high reflectivity when the difference in refractive index between two adjacent film layers is large.

[0120] In some possible implementations, the absolute value of the difference in refractive index between two adjacent film layers in at least one film stack in the reflective film 60 is greater than or equal to 0.6. Thus, when the number of film layers is constant, the reflectivity of the film stack for light of the reflected central wavelength can be further increased, thereby helping to improve the reflectivity of the reflective film 60 for light.

[0121] For example, as shown in FIG6 , the absolute value of the difference in refractive index between two adjacent film layers in the four film stacks of the reflective film 60 is greater than or equal to 0.6. However, in some implementations, the absolute value of the difference in refractive index between two adjacent film layers in some of the four film stacks of the reflective film 60 may be set to be greater than or equal to 0.6, while the absolute value of the difference in refractive index between two adjacent film layers in another portion may be set to be less than 0.6.

[0122] It should be noted that the absolute value of the difference in refractive index between two adjacent film layers in at least one film stack in the reflective film 60 may also be less than 0.6.

[0123] In the embodiment of the present application, each film stack in the reflective film 60 is composed of at least two film layers with different refractive indices. In some implementations, at least two film stacks in the reflective film 60 include two film layers with different refractive indices, which can simplify the film stack structure and help reduce the difficulty of stacking the film stacks. In other implementations, at least one film stack in the reflective film 60 can also include at least three film layers with different refractive indices.

[0124] Exemplarily, as shown in Figure 6, the reflective film 60 includes a first film stack 61, a second film stack 62, a third film stack 63 and a fourth film stack 64, the first film stack 61 includes a first film layer 611 and a second film layer 612 with different refractive indices, the second film stack 62 includes a third film layer 621 and a fourth film layer 622 with different refractive indices, the third film stack 63 includes a fifth film layer 631 and a sixth film layer 632 with different refractive indices, and the fourth film stack 64 includes a seventh film layer 641 and an eighth film layer 642 with different refractive indices.

[0125] In the embodiments of the present application, a material having a refractive index greater than or equal to 1.6 is defined as a high-refractive-index material, for example, a metal oxide or metal nitride having a refractive index greater than or equal to 1.6, such as a metal oxide containing Ti / Ta. A material having a refractive index less than 1.6 is defined as a low-refractive-index material, for example, a metal oxide or metal fluoride having a refractive index less than 1.6, such as SiO2, Al2O3, MgF2, etc.

[0126] There is no limitation on the materials of each film layer in the film stack. In some implementations, the refractive index of each film layer in the film stack is greater than or equal to 1.6. In other words, the film stack can be composed of at least two high-refractive-index materials. In other implementations, the refractive index of each film layer in the film stack is less than 0.6. In other words, the film stack can be composed of at least two low-refractive-index materials. In still other implementations, the refractive index of some film layers in the film stack is greater than or equal to 1.6, and the refractive index of other film layers is less than 1.6. In other words, the film stack can be composed of at least one high-refractive-index material and at least one low-refractive-index material.

[0127] In some possible implementations, the refractive index of each film layer in each film stack of the reflective film 60 is greater than or equal to 1.6, so that each film stack in the reflective film 60 is formed by a high refractive index material.

[0128] In other possible implementations, the refractive index of each film layer of a part of the film stacks in the reflective film 60 is greater than or equal to 1.6, the refractive index of a part of the film layers of another part of the film stacks is greater than or equal to 1.6, and the refractive index of another part of the film layers is less than 1.6, so that a part of the film stacks in the reflective film 60 are composed of high refractive index materials, and another part of the film stacks are composed of high refractive index materials and low refractive index materials.

[0129] In some further possible implementations, the refractive index of each film layer of each film stack of the reflective film 60 is less than 1.6, so that each film stack in the reflective film 60 is formed by a low-refractive-index material.

[0130] In some other possible implementations, the refractive index of a portion of the film layers in each film stack of the reflective film 60 is greater than or equal to 1.6, and the refractive index of another portion of the film layers is less than 1.6, so that each film stack of the reflective film 60 is composed of high refractive index material and low refractive index material.

[0131] In summary, the multiple film stacks of the reflective film 60 can all be composed of high refractive index materials, or the multiple film stacks of the reflective film 60 can all be composed of low refractive index materials and high refractive index materials, or the multiple film stacks of the reflective film 60 can all be composed of low refractive index materials.

[0132] It should be noted that the film stack to which each film layer belongs can be determined by the refractive index of the film layer and the thickness variation of the multiple film layers. Of course, other methods can also be used to determine the film stack to which each film layer belongs.

[0133] For example, as shown in Figure 6, the reflective film 60 includes a first film stack 61, a second film stack 62, a third film stack 63, and a fourth film stack 64. Among them, the first film stack 61 is composed of a first film layer 611 and a second film layer 612 with different refractive indices, and the thickness of multiple first film layers 611 is the same, and the thickness of multiple second film layers 612 is the same. The second film stack 62 is composed of a third film layer 621 and a fourth film layer 622 with different refractive indices, and the thickness of multiple third film layers 621 is the same, and the thickness of multiple fourth film layers 622 is the same. The third film stack 63 is composed of a fifth film layer 631 and a sixth film layer 632 with different refractive indices, and the thickness of multiple fifth film layers 631 is the same, and the thickness of multiple sixth film layers 632 is the same. The fourth film stack 64 is composed of a seventh film layer 641 and an eighth film layer 642, and the thickness of multiple seventh film layers 641 is the same, and the thickness of multiple eighth film layers 642 is the same. It can be seen that in the same film stack, the thickness of film layers with the same refractive index is the same. Therefore, the membrane stack to which the membrane layer belongs can be determined by the thickness change of the membrane layer.

[0134] Due to manufacturing tolerances, the thickness of films with the same refractive index within the same film stack may vary. For example, films with the same refractive index are considered to be the same stack if their thickness fluctuates within ±5%; if the thickness fluctuates beyond this range, they are considered to be different stacks.

[0135] In the embodiments of the present application, there is no limitation on the thickness of the film layer, wherein the thickness of the film layer may include but is not limited to 1 nm, 2 nm, 5 nm, 10 nm, 50 nm, 100 nm, 180 nm, 200 nm, etc.

[0136] In some possible implementations, at least one film layer in the film stack with a refractive index greater than or equal to 1.6 has a thickness greater than or equal to 80 nm and less than or equal to 150 nm. It will be appreciated that setting the thickness of the film layer with a refractive index greater than or equal to 1.6 to between 80 nm and 150 nm means limiting the thickness of the high-refractive-index material to between 80 nm and 150 nm. This can further improve the reflectivity of the film stack while maintaining a constant number of film layers.

[0137] In some possible implementations, the thickness of at least one film layer with a refractive index less than 1.6 in the film stack is greater than or equal to 100 nm and less than or equal to 180 nm. It will be appreciated that setting the thickness of the film layer with a refractive index less than 1.6 to between 100 nm and 180 nm means limiting the thickness of the low-refractive-index material to between 100 nm and 180 nm. This allows the reflectivity of the film stack to be further improved, given a given number of film layers.

[0138] In the above description, the reflective film 60 is a dielectric film. In this case, the dielectric film is composed of a plurality of stacked films, as shown in FIG6 . However, in some implementations, the reflective film 60 may also be a metal film. In this case, the metal film is also composed of a plurality of stacked films. In still other implementations, the reflective film 60 may also be a metal-dielectric film. In this case, as shown in FIG11 , the metal-dielectric film includes a metal layer 66 and a dielectric layer 65. The dielectric layer 65 is composed of a plurality of stacked films. The dielectric layer 65 is disposed between the metal layer 66 and the prism 50. FIG11 is a schematic cross-sectional view of another reflective film provided in an embodiment of the present application.

[0139] It should be noted that when the reflective film 60 is a metal film, since the metal film is composed of a metal material, the metal material has absorption properties and can improve the dispersion problem. Therefore, the complementary reflective film 60 is mainly used to improve the transmittance of the prism 50. When the reflective film 60 is a metal dielectric film, the complementary reflective film 60 can effectively balance the transmittance and dispersion problems, achieving high transmittance while improving or solving the dispersion problem.

[0140] The multiple reflective films 60 in the deflecting element 11 are of the same type. For example, as shown in FIG4 , two reflective films 60 are dielectric films. However, the deflecting element 11 may also include reflective films 60 of different types.

[0141] In some implementations, at least one of the multiple reflective films 60 of the folding element 11 can be set as a dielectric film, and the remaining reflective films 60 can be set as dielectric films or metal-dielectric films. For example, the number of reflective films 60 is two, one of the two reflective films 60 is a dielectric film, and the other is a metal film or a metal-dielectric film.

[0142] In other implementations, the first portion of the reflective films 60 of the deflecting element 11 may be configured as a dielectric film, the second portion of the reflective film 60 may be configured as a metal film, and the third portion of the reflective film 60 may be configured as a metal-dielectric film. For example, if there are three reflective films 60, the first reflective film 60 may be a dielectric film, the second reflective film 60 may be a metal film, and the third reflective film 60 may be a metal-dielectric film.

[0143] In some other implementations, a portion of the multiple reflective films 60 of the deflection element 11 may be set as dielectric films, and another portion of the reflective films 60 may be set as metal dielectric films.

[0144] In the description of the embodiments of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to a fixed connection, an indirect connection via an intermediate medium, internal communication between two components, or an interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on specific circumstances.

[0145] In the embodiments of the present application, any device or element referred to or implied must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present application. In the description of the embodiments of the present application, the meaning of "plurality" is two or more, unless otherwise specifically specified.

[0146] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the embodiments of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0147] The term "plurality" in this document refers to two or more. The term "and / or" in this document simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. Furthermore, the character " / " in this document generally indicates an "or" relationship between the related objects; in a formula, the character " / " indicates a "division" relationship between the related objects.

[0148] It will be understood that the various numerical numbers involved in the embodiments of the present application are merely distinctions for the convenience of description and are not intended to limit the scope of the embodiments of the present application.

Claims

1. A reflective film, characterized in that: comprising a plurality of membrane stacks arranged in a stacked manner; The optical thicknesses of two adjacent film stacks are different. The two adjacent film stacks are used to reflect light of different central wavelengths. The reflectivity of each film stack to the reflected light of the central wavelength is greater than or equal to 80%. Each film stack includes multiple stacked film layers, and the refractive indices of two adjacent film layers are different.

2. The reflective film according to claim 1, wherein The absolute value of the difference in refractive index between two adjacent film layers in at least one of the film stacks is greater than or equal to 0.

6.

3. The reflective film according to claim 1 or 2, wherein: The reflectivity of each film stack to the reflected light of the central wavelength is greater than or equal to 98%.

4. The reflective film according to any one of claims 1 to 3, characterized in that The refractive index of each film layer of at least one of the film stacks is greater than or equal to 1.

6.

5. The reflective film according to any one of claims 1 to 4, characterized in that The refractive index of each film layer of at least one of the film stacks is less than 1.

6.

6. The reflective film according to any one of claims 1 to 5, characterized in that The refractive index of a portion of the film layers of at least one of the film stacks is greater than or equal to 1.6, and the refractive index of another portion of the film layers is less than 0.

6.

7. The reflective film according to any one of claims 1 to 6, characterized in that The thickness of the film layer with a refractive index greater than or equal to 1.6 in at least one of the film stacks is greater than or equal to 80 nm and less than or equal to 150 nm.

8. The reflective film according to any one of claims 1 to 7, wherein The thickness of the film layer with a refractive index less than 1.6 in at least one of the film stacks is greater than or equal to 100 nm and less than or equal to 180 nm.

9. The reflective film according to any one of claims 1 to 8, characterized in that At least two of the film stacks include two film layers having different refractive indices.

10. The reflective film according to any one of claims 1 to 9, characterized in that The optical thicknesses of any two of the film stacks are different.

11. The reflective film according to any one of claims 1 to 10, characterized in that The reflective film is a dielectric film; or The reflective film is a metal film; or The reflective film is a metal dielectric film, which includes a metal layer and a dielectric layer formed by the multiple film stacks.

12. A deflecting element, characterized in that: comprising a prism and a plurality of reflective films according to any one of claims 1 to 11; The prism has a plurality of non-total reflection surfaces for reflecting light, and each of the non-total reflection surfaces is provided with a reflective film; The number of film stacks of any two of the reflective films is the same, and along the path of light passing through the multiple non-total reflection surfaces, in two adjacent reflective films, the i-th film stack from the prism to the air in one of the reflective films is used to reflect light with a central wavelength of λ1, and the n-th film stack from the prism to the air in the other reflective film is used to reflect light with the same central wavelength λ2, the λ1 is the same as the λ2, and the optical thickness of the i-th film stack and the n-th film stack is the same; wherein, i+n=m+1, i≤m, n≤m, i, n and m are all positive integers, and m is the number of the film stacks of each of the reflective films.

13. The deflecting element according to claim 12, characterized in that: The prism has an even number of the non-total reflection surfaces.

14. The deflecting element according to claim 12 or 13, characterized in that: Each of the reflective films is a dielectric film or a metal film.

15. The deflecting element according to claim 12 or 13, characterized in that: The reflective film is a metal dielectric film, which includes a metal layer and a dielectric layer located between the metal layer and the prism.

16. A camera module, characterized in that: comprising an image sensor, a lens, and a deflecting element according to any one of claims 12 to 15; The lens and the image sensor are arranged on the same side of the deflecting element, or the lens and the image sensor are respectively arranged on two opposite sides of the deflecting element.

17. An electronic device, characterized in that: It comprises a housing and the camera module as claimed in claim 16, wherein the camera module is mounted on the housing.

Images