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 film, folding element, camera module and electronic device

[0001] The present application claims priority to the Chinese patent application No. 202410239066.X, filed on March 01, 2024, and entitled "Reflective film, folding element, camera module and electronic device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

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

[0003] Camera modules have become an indispensable functional component in electronic products such as mobile phones, tablets, notebook computers and wearable devices. With the development of lightweight and multifunctional electronic devices, the camera modules thereon are gradually developing towards miniaturization and thinness. The shooting effect and demand are increasingly approaching the level of single-lens reflex cameras, and the size and functional effect of the camera module have gradually become one of the important features of electronic devices. The camera module includes a lens assembly and an image sensor. The lens assembly is usually formed by arranging a plurality of lens lenses in sequence along the optical axis direction. Light is projected to the image sensor after passing through the lens assembly to realize photoelectric conversion and then used for imaging. In the related art, a periscopic design is adopted for the camera module to achieve long focal length to meet the distance shooting requirement. However, the periscopic camera module has a large size, which increases the difficulty of miniaturization of electronic devices. SUMMARY

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

[0005] The first aspect of the present application provides a reflective film, comprising a plurality of film stacks arranged in layers. Wherein the optical thickness of the adjacent two film stacks is different, the adjacent two film stacks are used for reflecting light of different center wavelengths, the reflectivity of each film stack to the reflected center wavelength light is greater than or equal to 80%, each film stack comprises a plurality of film layers arranged in layers, and the refractive index of the adjacent two film layers is different. In this way, the reflective film can reflect light of different center wavelengths through different numbers of film stacks, which can improve the reflectivity of the reflective film to light of different center wavelengths.

[0006] In a possible implementation, the absolute value of the difference between the refractive indices of the adjacent two film layers in at least one film stack is greater than or equal to 0.6. In this way, when the number of film layers is certain, the reflectivity of the film stack to the reflected light can be further improved, which helps to improve the reflectivity of the reflective film to light.

[0007] In one possible implementation, the reflectivity of each film stack to the reflected light of the central wavelength is greater than or equal to 98%, and the reflectivity of the film to the light can be further increased, thereby further increasing the transmittance.

[0008] In one possible implementation, the refractive index of each film layer of the at least one film stack is greater than or equal to 1.6. In this way, the reflectivity of the film stack to the reflected light can be increased.

[0009] In one possible implementation, the refractive index of each film layer of the at least one film stack is less than 1.6. In this way, the reflectivity of the film stack to the reflected light can be increased.

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

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

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

[0013] In one possible implementation, the at least two film stacks include two film layers with different refractive indices. In this way, the structure of the film stack can be simplified, and the difficulty of stacking the film stack can be reduced.

[0014] In one possible implementation, the optical thickness of any two film stacks is different. In this way, the number of film stacks can be reduced, and the thickness of the reflective film can be reduced.

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

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

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

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

[0019] In a possible implementation, each film stack has a reflectivity of less than 50% for light of other center wavelengths than the corresponding center wavelength.

[0020] In a second aspect, the application provides a turning element comprising a prism and a plurality of reflecting films according to any one of the first aspect. The prism has a plurality of non-total reflection surfaces for reflecting light, and each non-total reflection surface is provided with one reflecting film. The number of film stacks of any two reflecting films is the same, and along the path of light passing through the plurality of non-total reflection surfaces, in any two adjacent reflecting films, the i-th film stack from the prism to air in one of the two reflecting films is used for reflecting light of a center wavelength λ1, and the n-th film stack from the prism to air in the other of the two reflecting films is used for reflecting light of the same center wavelength λ2, λ1 is the same as 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 positive integers, and m is the number of film stacks of each reflecting film.

[0021] By providing reflecting films on the non-total reflection surfaces that do not satisfy the total reflection condition, total reflection can occur at the non-total reflection surfaces, so that the prism can reflect light multiple times, thereby reducing the volume of the prism and further reducing the volume of the turning element. In addition, by using reflecting films to achieve total reflection, the total reflection angle of the prism can be decoupled from the total reflection angle, so that the prism can reflect light multiple times at any angle, thereby achieving high transmittance while reducing the volume of the prism.

[0022] In addition, along the path of light passing through the plurality of non-total reflection surfaces, the two adjacent reflecting films are complementary, so that the optical path difference of light of different center wavelengths passing through all the non-total reflection surfaces is zero or smaller, thereby improving or solving the chromatic dispersion while improving the transmittance. Wherein, complementary means that the number of film stacks in the two adjacent reflecting films is the same, the composition of the film stacks is the same, and the arrangement 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, so that the optical path difference of light of different center wavelengths passing through all the non-total reflection surfaces is zero, and the chromatic dispersion problem can be solved.

[0024] In a possible implementation, each reflecting film is a dielectric film. In this way, the volume of the turning element can be further reduced on the basis of solving the chromatic dispersion problem and achieving high transmittance.

[0025] In a possible implementation, each reflecting film is a metal film. In this way, the volume of the turning element can be further reduced on the basis of solving the chromatic dispersion problem and achieving high transmittance.

[0026] In a possible implementation, the reflective film is a metal dielectric film, and the metal dielectric film includes a metal layer and a dielectric layer between the metal layer and the prism. In this way, the dispersion or the improvement problem can be solved by the absorption characteristics of the metal material of the metal layer, and high transmittance can be achieved, when the prism with an arbitrary angle has an even number of or an odd number of non-total reflection surfaces.

[0027] The third aspect of the present application provides a camera module, including an image sensor, a lens and the folding element of any one of the second aspect. The lens and the image sensor are arranged on the same side of the folding element, or the lens and the image sensor are arranged on opposite sides of the folding element.

[0028] Since the folding element is composed of the prism with an arbitrary angle and the reflective film, the folding element has high transmittance while being small in size, so that the size of the camera module can be reduced, and the difficulty of miniaturization of the electronic device can be reduced.

[0029] The fourth aspect of the present application provides an electronic device, including a shell and the camera module of the third aspect, and the camera module is mounted on the shell. BRIEF DESCRIPTION OF DRAWINGS

[0030] FIG. 1 is a cross-sectional view of a camera module in the related art;

[0031] FIG. 2A is a schematic diagram of a prism reflecting light through an odd number of reflection surfaces in the related art;

[0032] FIG. 2B is a schematic diagram of a prism reflecting light through an even number of reflection surfaces in the related art;

[0033] FIG. 3 is a structural schematic diagram of an electronic device provided by an embodiment of the present application;

[0034] FIG. 4 is a structural schematic diagram of a camera module provided by an embodiment of the present application;

[0035] FIG. 5 is a structural schematic diagram of another camera module provided by an embodiment of the present application;

[0036] FIG. 6 is a cross-sectional schematic diagram of a reflective film provided by an embodiment of the present application;

[0037] FIG. 7 is a structural schematic diagram of a folding element provided by an embodiment of the present application;

[0038] FIG. 8 is a structural schematic diagram of another folding element provided by an embodiment of the present application;

[0039] FIG. 9 is a reflectivity curve diagram of a first reflective film in FIG. 7 for different centers;

[0040] FIG. 10 is a reflectivity curve diagram of a second reflective film in FIG. 7 for different center wavelengths;

[0041] FIG. 11 is a schematic cross-sectional view of another reflective film according to embodiments of the present application.

[0042] Marker Description: 100, electronic device; 10, camera module; 11, folding element; 12, lens; 13, image sensor; 20, shell; 30, speaker opening; 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 embodiment part of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0044] For ease of understanding, first, the related technical terms involved in the embodiments of the present application are explained and described.

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

[0046] Transmittance: the ratio of the radiation energy projected and transmitted through an object to the total radiation energy projected onto the object during the process of the incident light flux from the illuminated surface or the medium incident surface to the other surface, which is called the transmittance of the object.

[0047] 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 760-622 nm, and the center wavelength is 660 nm, or the wavelength range of green light is 577-492 nm, and the center wavelength is 550 nm, etc.

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

[0049] Total internal reflection, also known as total reflection (total internal reflection, TIR), is an optical phenomenon. When light enters from a medium with a higher refractive index to a medium with a lower refractive index, if the incident angle is greater than a certain critical angle (the light is far away from the normal), the refracted light will disappear, and all the incident light will be reflected without entering the low refractive index medium.

[0050] Group delay effect: mainly embodied in different frequencies of light corresponding to different refractive index, so that the same film system for different light reflectivity is different, and the reflection depth is different.

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

[0052] Optical path difference, as the name implies, is the difference between the optical paths of two beams of light.

[0053] Figure 1 is a sectional view of a camera module in the related art, Figure 2A is a schematic diagram of a prism reflecting light through an odd number of reflecting surfaces in the related art, and Figure 2B is a schematic diagram of a prism reflecting light through an even number of reflecting surfaces in the related art.

[0054] In the 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. Among them, the lens assembly 230 is arranged between the prism 210 and the image sensor 220, and the lens assembly 230 includes a plurality of parallel placed lenses, which realizes long focal length design and meets the demand of long distance shooting. However, the volume of the periscope camera module 200 is large, which will increase the difficulty of miniaturization of electronic devices.

[0055] In order to reduce the difficulty of miniaturization of electronic devices, in an embodiment, the volume of the periscope camera module 200 can be compressed by multiple reflections of the prism 210. Among them, the prism 210 has a plurality of reflecting surfaces for reflecting light, and at the same time, a total reflection film 240 is coated on the reflecting surface which does not meet the total reflection condition (as shown in Figure 2A), so that the size of the prism 210 can be made smaller, thereby reducing the volume of the periscope camera module 200, and further reducing the difficulty of miniaturization of electronic devices.

[0056] As shown in FIG. 2A, the prism 210 has three reflecting surfaces, including a total reflection surface d1, a first non-total reflection surface d2, and a second non-total reflection surface d3. The light rays satisfy the total reflection condition at the total reflection surface d1, and no total reflection film 240 is coated on the total reflection surface d1. The light rays do not satisfy the total reflection condition at the first non-total reflection surface d2 and the second non-total reflection surface d3, and thus total reflection films 240 are coated on the first non-total reflection surface d2 and the second non-total reflection surface d3, so that the light rays are 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, so that light of different central wavelengths is reflected at different depths of the total reflection film 240 (as shown by M1 and M2 in FIG. 2A), and thus the optical paths of the light of different central wavelengths after passing through the total reflection film 240 are different, and the light of different central wavelengths after passing through the total reflection film 240 has an optical path difference. Therefore, when the light rays are reflected an odd number of times in the prism 210, the light of different central wavelengths leaving the prism 210 has an optical path difference, so that the light of different central wavelengths leaving the prism 210 does not coincide, resulting in a dispersion problem, so that one of the first non-total reflection surface d2 and the second non-total reflection surface d3 forms a red edge, and the other forms a blue edge.

[0057] In another embodiment, as shown in FIG. 2B, the prism 210 has two reflecting surfaces, which are the first non-total reflection surface d2 and the second non-total reflection surface d3. The light rays do not satisfy the total reflection condition at the first non-total reflection surface d2 and the second non-total reflection surface d3, and thus total reflection films 240 (not shown in FIG. 2B) are coated on the first non-total reflection surface d2 and the second non-total reflection surface d3, so that the light rays are totally reflected at the first non-total reflection surface d2 and the second non-total reflection surface d3. The total reflection film 240 is a dielectric film, and the light of different central wavelengths (as shown by M1 and M2 in FIG. 2B) has an optical path difference at the two reflecting surfaces. As shown in FIG. 2B, when the light of different central wavelengths leaving the prism 240 coincides, no dispersion problem occurs, and β = α, β = 180° - 3α = α, i.e., α = 45°. When α ≠ 45°, β ≠ α, and the light of different central wavelengths leaving the prism 240 does not coincide, and a dispersion problem occurs. Therefore, when the light rays are 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 occurs.

[0058] Therefore, the application provides a reflective film 60, a folding element 11, a camera module 10 and an electronic device 100. The folding element 11 includes the prism 50 and the reflective film 60. The prism 50 has a plurality of reflective surfaces. The reflective film 60 is plated on a non-total reflection surface in the plurality of reflective surfaces, so that the light is totally reflected at the non-total reflection surface. The total reflection surface does not need to be plated with the reflective film 60. Along the path of the light passing through all the reflective surfaces, the adjacent two reflective films 60 are complementary. The prism 50 with any angle can have high transmittance, and the dispersion problem can be improved or solved. The volume of the camera module 10 can be reduced, and the difficulty of miniaturization of the electronic device 100 is reduced.

[0059] The electronic device 100 can include, but is not limited to, a mobile phone, a tablet computer, a notebook 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.

[0060] In the application, the electronic device 100 is taken as a mobile phone as an example. The mobile phone can be a straight phone, or the mobile phone can also be a folding phone. Hereinafter, the electronic device 100 is taken as a straight phone as an example.

[0061] FIG. 3 is a structural schematic diagram of an electronic device according to an embodiment of the application.

[0062] Referring to FIG. 3, the electronic device 100 includes a display screen, a housing 20 and a camera module 10. The camera module 10 is installed on the housing 20, and is used to realize the function of shooting. The display screen is installed on the housing 20, and is used to display text, images and the like.

[0063] The camera module 10 can be located on the front surface (the surface with the display screen) of the electronic device 100, and is used for self-shooting or shooting other objects. Alternatively, referring to FIG. 3, the camera module 10 can also be located on the back surface (the surface away from the display screen) of the electronic device 100, and is used for shooting other objects, and of course can also be used for self-shooting.

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

[0065] The electronic device 100 can further include other structural components. For example, referring to FIG. 3, the housing 20 of the electronic device 100 can further have a speaker opening 30 formed therein. The speaker opening 30 can be configured to allow the electronic device 100 to output audio. Referring to FIG. 3, the housing 20 of the electronic device 100 can further have a data port 40 formed therein. The data port 40 can be configured to allow the electronic device 100 to be connected to an external device (e.g., a wired earphone, a wired multimedia device, etc.).

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

[0067] FIG. 4 is a structural schematic diagram of a camera module according to an embodiment of the present application.

[0068] As shown in FIG. 4, the camera module 10 includes an image sensor 13, a lens 12, and a folding element 11. The folding element 11 is configured to fold an optical axis, so that the camera module 10 has a periscopic architecture. The folding element 11 is configured to receive incident light. The incident light exits the folding element 11 after multiple total reflections inside the folding element 11 and is received by a light receiving surface (also referred to as an imaging surface) of the image sensor 13, so as to achieve imaging. By multiple total reflections of the incident light by the folding element 11, the volume of the folding element 11 can be further reduced, so as to achieve the purpose of reducing the volume of the camera module 10. At the same time, the folding element 11 has high transmittance to the incident light, and can improve or solve the problem of chromatic dispersion.

[0069] The image sensor 13 can be a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). Alternatively, the image sensor 13 can be another device capable of photoelectric conversion.

[0070] The lens 12 can include one or more lens pieces, which are not specifically limited herein.

[0071] It should be noted that the camera module 10 can further include other devices. For example, the camera module 10 can further include a lens barrel and a filter. The lens barrel is configured to accommodate the image sensor 13, the filter, or the lens 12.

[0072] As shown in FIG. 4, the lens 12 and the image sensor 13 are disposed on the same side of the folding element 11, and in this case, the folding element 11 is configured to receive the incident light emitted by the lens 12 and project the incident light to the light-sensitive surface of the image sensor 13.

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

[0074] In the embodiment of the present application, the folding element 11 includes a prism 50 and a plurality of reflecting films 60. The prism 50 has a plurality of non-total reflection surfaces for reflecting light, and each non-total reflection surface is provided with a reflecting film 60, so that the reflecting film 60 and the non-total reflection surface are in one-to-one correspondence. For example, as shown in FIG. 4, the number of reflecting films 60 is two, and correspondingly, the number of non-total reflection surfaces is also two. Each reflecting film 60 is a dielectric film.

[0075] The specific structure of the prism 50 is not limited here. In some embodiments, as shown in FIG. 4, the prism 50 can be an isosceles trapezoid. In other embodiments, as shown in FIG. 5, the prism 50 can also be a parallelogram.

[0076] In some embodiments, the prism 50 can have an even number of non-total reflection surfaces. For example, as shown in FIG. 4, the prism 50 has two non-total reflection surfaces, and correspondingly, the number of reflecting films 60 is two. Of course, the number of non-total reflection surfaces can also be more than two, such as 4, 6, 8, etc.

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

[0078] The prism 50 also has a total reflection surface 53, and the number of total reflection surfaces 53 can be one or more. For example, as shown in FIG. 4, the number of total reflection surfaces 53 is one. Or, as shown in FIG. 5, the number of total reflection surfaces 53 is two.

[0079] FIG. 6 is a cross-sectional schematic diagram of a reflecting film provided by an embodiment of the present application.

[0080] Referring to FIG. 6, each reflective film 60 includes a plurality of film stacks arranged in a stack. The optical thickness of adjacent two film stacks is different, and the adjacent two 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 a plurality of film layers arranged in a stack, and the refractive index of adjacent two film layers is different. In this way, the reflective film 60 can reflect light of different central wavelengths through different numbers of film stacks, which can improve the reflectivity of the reflective film 60 to light of different central wavelengths, thereby achieving high optical efficiency, and at the same time, the dispersion problem of the prism 50 can be solved or improved.

[0081] For example, as shown in FIG. 6, the reflective film 60 includes four film stacks, and the four film stacks include a first film stack 61, a second film stack 62, a third film stack 63, and a fourth film stack 64 arranged in a stack. Of course, the number of film stacks can be more than or less than four.

[0082] For example, as shown in FIG. 6, the film stack can include six film layers arranged in a stack. Of course, the number of film layers in the film stack can be more than or less than six.

[0083] In the embodiment of the present application, each film stack reflects light of other central wavelengths in addition to reflecting light of the corresponding central wavelength, and the reflectivity of the film stack to the light of the other central wavelengths is less than 80%. For example, as shown in FIG. 6, the first film stack 61 is used to reflect blue light c1 of a central wavelength of 440 nm, and also reflects red light c4, green light c2, yellow light c3, and light of other central wavelengths. The reflectivity of the first film stack 61 to the red light c4, the green light c2, the yellow light c3, and the light of other central wavelengths can be less than 50%.

[0084] The reflectivity of each film stack to the light of other central wavelengths in addition to the corresponding central wavelength can 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 to the light of other central wavelengths in addition to the corresponding central wavelength can be less than 50%. In this way, the transmittance of each film stack to the light of other central wavelengths in addition to the corresponding central wavelength can be improved, and it is ensured that the reflective film 60 fully reflects light of each central wavelength through different numbers of film stacks.

[0086] FIG. 7 is a structural schematic diagram of a folding element provided in an embodiment of the present application, and FIG. 8 is a structural schematic diagram of another folding element provided in an embodiment of the present application.

[0087] As shown in FIG. 7, along the path of light passing through a plurality of non-total reflection surfaces (such as the solid line with arrows in FIG. 7 or FIG. 8), the two adjacent reflective films 60 are complementary, which can make the prism 50 of any angle have high transmittance while improving or solving the dispersion problem. Among them, complementary refers to the same number of film stacks, the same composition of film stacks, and the opposite arrangement order of film stacks relative to the prism 50 in the two adjacent reflective films 60. The same composition of film stacks can be understood as the same type, arrangement, thickness, and number of film layers in the two film stacks of the same optical thickness.

[0088] Specifically, the number of film stacks of any two reflective films 60 is the same, along the path of light passing through a plurality of non-total reflection surfaces (such as the solid line with arrows in FIG. 7 or FIG. 8), in the two adjacent reflective films 60, the i-th film stack from the prism 50 to the air in one of the two reflective films 60 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, λ1 and λ2 are the same, in other words, the i-th film stack from the prism 50 to the air in one of the two reflective films 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 optical thickness of the i-th film stack and the n-th film stack is the same, and the composition of the i-th film stack and the n-th film stack is the same. Among them, i+n=m+1, i≤m, n≤m, i, n and m are positive integers, and m is the number of film stacks of each reflective film 60. In this way, the two adjacent reflective films 60 are complementary, which can make the prism 50 of any angle have high transmittance while improving or solving the dispersion problem.

[0089] The complementary properties of the two adjacent reflective films 60 are described below by way of example:

[0090] Exemplarily, as shown in FIG. 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 turn after reflection, and then exits the prism 50 through the total reflection surface 53.

[0091] Continuing to refer to FIG. 7, along the path of light through all the non-total internal 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 internal reflection surface 51, and the first reflective film 60A includes four film stacks arranged in a stack, a first film stack al of the four film stacks is closest to the first non-total internal reflection surface 51, and a fourth film stack a4 of the four film stacks is farthest from the first non-total internal reflection surface 51. The second reflective film 60B is disposed on the second non-total internal reflection surface 52, and the second reflective film 60B includes four film stacks arranged in a stack, a first film stack bl of the four film stacks is closest to the second non-total internal reflection surface 52, and a fourth film stack b4 of the four film stacks is farthest from the second non-total internal reflection surface 52.

[0092] In the first reflective film 60A, the first film stack al and the fourth film stack a4 are used to reflect light of the same central wavelength. The second film stack a2 and the third film stack b3 are used to reflect light of the same central wavelength. The third film stack a3 and the second film stack b2 are used to reflect light of the same central wavelength. The fourth film stack a4 and the first film stack bl are used 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] In the first reflective film 60A, the first film stack al and the fourth film stack b4 have the same optical thickness and structure. The second film stack a2 and the third film stack b3 have the same optical thickness and structure. The third film stack a3 and the second film stack b2 have the same optical thickness and structure. The fourth film stack a4 and the first film stack bl have the same optical thickness and structure.

[0094] The following takes blue light cl, green light c2, yellow light c3 and red light c4 of four different central wavelengths of light as an example to illustrate how two adjacent reflective films 60 reflect light of different central wavelengths to achieve complementation.

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

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

[0097] Thus, the ith film stack in the first reflecting film 60A and the nth film stack in the second reflecting film 60B reflect light with the same center wavelength, and the optical thicknesses of the ith film stack and the nth film stack are the same. At this time, 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 al in the first reflecting film 60A and the fourth film stack b4 in the second reflecting film 60B reflect blue light cl with the same center wavelength, and the optical thicknesses of the first film stack al and the fourth film stack b4 are the same.

[0098] FIG. 9 is a graph of reflectivity curves of the first reflecting film in FIG. 7 for different center wavelengths. In FIG. 9, R represents reflectivity, gl represents a reflectivity curve of the first reflecting film 60A for blue light cl, g2 represents a reflectivity curve of the first reflecting film 60A for green light c2, g3 represents a reflectivity curve of the first reflecting film 60A for yellow light c3, and g4 represents a reflectivity curve of the first reflecting film 60A for red light c4.

[0099] In the process in which the first reflecting film 60A in FIG. 7 reflects light with different center wavelengths, referring to FIG. 9, blue light cl is reflected by the first film stack al in the first reflecting film 60A, green light c2 is reflected by the first film stack al and the second film stack a2 in the first reflecting film 60A, yellow light c3 is reflected by the first film stack al, the second film stack a2, and the third film stack a3 in the first reflecting film 60A, and red light c4 is reflected by the first film stack al, the second film stack a2, the third film stack a3, and the fourth film stack a4 in the first reflecting film 60A. Thus, light with different center wavelengths has a path difference after passing through the first reflecting film 60A, for example, the path difference of red light c4 and green light c2 on the first reflecting film 60A is the second film stack a2 and the third film stack a3.

[0100] It can be understood that the first film stack al of the first reflecting film 60A can reflect light of each center wavelength, and reflect all the blue light cl corresponding to the center wavelength of 440 nm, so that light of each center wavelength except the blue light cl reaches the second film stack a2. Similarly, the second film stack a2 of the first reflecting film 60A can reflect light of each center wavelength except the blue light cl, and reflect all the green light c2 corresponding to the center wavelength of 550 nm under the joint action of the first film stack al and the second film stack a2. The third film stack a3 of the first reflecting film 60A can reflect light of each center wavelength except the blue light cl and the green light c2, and reflect all the yellow light c3 corresponding to the center wavelength of 570 nm under the joint action of the first film stack al, the second film stack a2 and the third film stack a3. The fourth film stack a4 of the first reflecting film 60A can reflect light of each center wavelength except the blue light cl, the green light c2 and the yellow light c3, and reflect all the red light c4 corresponding to the center wavelength of 660 nm under the joint action of the first film stack al, the second film stack a2, the third film stack a3 and the fourth film stack a4. Therefore, light of different center wavelengths has a path difference after passing through the first reflecting film 60A.

[0101] The reflectivity curves of the second reflecting film for light of different center wavelengths in FIG. 10 are shown in FIG. 10, where R represents reflectivity, gl represents the reflectivity curve of the second reflecting film 60B for the blue light cl, g2 represents the reflectivity curve of the second reflecting film 60B for the green light c2, g3 represents the reflectivity curve of the second reflecting film 60B for the yellow light c3, and g4 represents the reflectivity curve of the second reflecting film 60B for the red light c4.

[0102] In the process of reflecting light of different center wavelengths by the second reflecting film 60B in FIG. 7, referring to FIG. 10, the blue light cl is reflected by the first film stack bl, the second film stack b2, the third film stack b3 and the fourth film stack b4 in the second reflecting film 60B, the green light c2 is reflected by the first film stack bl, the second film stack b2 and the third film stack b3 in the second reflecting film 60B, the yellow light c3 is reflected by the first film stack bl and the second film stack b2 in the second reflecting film 60B, and the red light c4 is reflected by the first film stack bl in the second reflecting film 60B. It can be understood that light of different center wavelengths has a path difference after passing through the second reflecting film 60B, for example, the path difference between the red light c4 and the green light c2 is the second film stack b2 and the third film stack b3.

[0103] It can be understood that the first film stack of the second reflecting film 60B can reflect light of each center wavelength, and reflect all red light c4 corresponding to a center wavelength of 660 nm, so that light of each center wavelength except red light c4 reaches the second film stack b2. Similarly, the second film stack b2 of the second reflecting film 60B can reflect light of each center wavelength except red light c4, and reflect all yellow light c3 corresponding to a center wavelength of 570 nm under the joint action of the first film stack b1 and the second film stack b2. The third film stack b3 of the second reflecting film 60B can reflect light of each center wavelength except red light c4 and yellow light c3, and reflect all green light c2 corresponding to a center wavelength of 550 nm under the joint action of the first film stack b1, the second film stack b2 and the third film stack b3. The fourth film stack b4 of the second reflecting film 60B can reflect light of each center wavelength except red light c4, green light c2 and yellow light c3, and reflect all blue light c1 corresponding to a center wavelength of 440 nm under the joint action of the first film stack b1, the second film stack b2, the third film stack b3 and the fourth film stack b4. Thus, it can be known that the light of different center wavelengths has a path difference after passing through the second reflecting film 60B.

[0104] It can be known from FIGS. 9 and 10 that the path difference of red light c4 and green light c2 on the first reflecting film 60A is the second film stack a2 and the third film stack a3, and the path difference of red light c4 and green light c2 is the second film stack b2 and the third film stack b3. The optical thickness of the second film stack a2 of the first reflecting film 60A is the same as the optical thickness of the third film stack b3 of the second reflecting film 60B, and the optical thickness of the second film stack a3 of the first reflecting film 60A is the same as the optical thickness of the third film stack b2 of the second reflecting film 60B. Therefore, the absolute value of the path difference of red light c4 and green light c2 on the first reflecting film 60A is the same as the path difference of red light c4 and green light c2 on the second reflecting film 60B.

[0105] It can be known from FIG. 7 that the film stack arrangement order of the first reflecting film 60A and the second reflecting film 60B is opposite, so that the path difference of red light c4 and green light c2 on the second reflecting film 60B is negative, and thus the sum of the path differences of red light c4 and green light c2 at the first reflecting film 60A and the second reflecting film 60B is zero. Therefore, the path of light of any center wavelength passing through adjacent two reflecting films 60 is the same, so that the path difference of light of any two center wavelengths passing through adjacent two reflecting films 60 is the same, and thus the path difference of light of any two center wavelengths at adjacent two reflecting films 60 is zero, so that light of different center wavelengths passing through adjacent two reflecting films 60 will not be deflected, and will not appear color dispersion phenomenon.

[0106] It can be understood that the optical path difference of the red light c4 and the green light c2 on the first reflecting film 60A and the optical path difference of the red light c4 and the green light c2 on the second reflecting film 60B are equal to A+(-B). Wherein, A=B, A is the optical path difference of the red light c4 and the green light c2 on the first reflecting film 60A, and B is the optical path difference of the red light c4 and the green light c2 on the second reflecting film 60B. Since the arrangement order of the film stacks in the first reflecting film and the second reflecting film 60B is opposite, the optical path difference of the red light c4 and the green light c2 passing through one reflecting film 60 of the adjacent two reflecting films 60 is positive, and the optical path difference of the red light c4 and the green light c2 passing through the other reflecting film 60 is negative, therefore, A is positive and B is negative, or A is negative and B is positive.

[0107] When the number of non-total reflecting surfaces is even, the sum of the optical path differences of any two center wavelengths of light passing through the reflecting films 60 on all non-total reflecting surfaces is zero, which can solve the dispersion problem. At the same time, the reflectivity of each film stack to the light of the corresponding center wavelength is greater than 80%, so that the reflectivity of the reflecting film 60 is high, which can improve the transmittance of the prism 50. In addition, the angle of the prism 50 and the dispersion problem can be decoupled, so that the prism 50 can be any angle.

[0108] When the number of non-total reflecting surfaces is odd, the sum of the optical path differences of any two center wavelengths of light passing through the reflecting films 60 on all non-total reflecting surfaces is reduced, which can effectively improve the dispersion problem. At the same time, the reflectivity of each film stack to the light of the corresponding center wavelength is greater than 80%, so that the reflectivity of the reflecting film 60 is high, which can improve the transmittance of the prism 50. In addition, the angle of the prism 50 and the dispersion problem can be decoupled, so that the prism 50 can be any angle.

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

[0110] When the first reflective film 60A is provided on the second non-total reflection surface 52, in the first reflective film 60A, the first film stack al is used to reflect red light c4 having a center wavelength of 660 nm, the second film stack a2 is used to reflect yellow light c3 having a center wavelength of 570 nm, the third film stack a3 is used to reflect green light c2 having a center wavelength of 550 nm, and the fourth film stack a4 is used to reflect blue light cl having a center wavelength of 440 nm. At this time, the reflectance curve of the first reflective film 60A for light having each center wavelength is the same as that of FIG. 10.

[0111] When the second reflective film 60B is provided on the first non-total reflection surface 51, in the second reflective film 60B, the first film stack bl is used to reflect blue light cl having a center wavelength of 440 nm, the second film stack b2 is used to reflect green light c2 having a center wavelength of 550 nm, the third film stack b3 is used to reflect yellow light c3 having a center wavelength of 570 nm, and the fourth film stack b4 is used to reflect red light c4 having a center wavelength of 660 nm. At this time, the reflectance curve of the second reflective film 60B for light having each center wavelength is the same as that of FIG. 9.

[0112] In some possible implementations, the optical thicknesses of any two film stacks are different, for example, as shown in FIG. 6, the optical thicknesses of the four film stacks in the reflective film 60 are all different. In this way, the number of film stacks can be reduced, which helps to reduce the thickness of the reflective film 60.

[0113] It should be noted that the optical thicknesses of any two film stacks in the reflective film 60 are different. In some implementations, the optical thicknesses of some film stacks in the reflective film 60 can be the same, and the optical thicknesses of other film stacks can be different.

[0114] In some possible implementations, the reflectance of each film stack for light having a center wavelength to be reflected is greater than or equal to 98%, and the reflectance of the reflective film 60 for light can be further improved, thereby further improving the transmittance of the turning element 11.

[0115] For example, as shown in FIG. 6, the reflectance of each of the four film stacks in the reflective film 60 for light having a center wavelength to be reflected is greater than or equal to 98%.

[0116] It is to be noted that, in addition to setting the reflectivity of each film stack in the reflection film 60 to be greater than or equal to 98% for the light of the central wavelength to be reflected, the reflectivity of a part of the film stacks in the reflection film 60 can be set to be greater than or equal to 98% and the reflectivity of another part of the film stacks can be set to be greater than 80% and less than 98% for the light of the central wavelength to be reflected. For example, the reflection film 60 includes four film stacks, in which the reflectivity of three of the film stacks is greater than or equal to 98% for the light of the central wavelength to be reflected and the reflectivity of the remaining one of the film stacks is greater than 80% and less than 98% for the light of the central wavelength to be reflected.

[0117] In some possible implementations, the number of film layers of at least two of the film stacks of the reflection film 60 is the same. For example, as shown in FIG. 6, the number of the film stacks is four and each of the film stacks is composed of six film layers. However, the number of the film stacks in which the number of the film layers is the same can also be less than four, for example, three of the four film stacks are composed of six film layers and the remaining one of the film stacks is composed of five film layers.

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

[0119] In some possible implementations, the number of film layers in at least one of the film stacks can be greater than or equal to 2 and less than or equal to 50, for example, as shown in FIG. 6, the number of film layers in each of the film stacks is greater than 2 and less than 20. In this way, when the difference between the refractive indexes of the adjacent two film layers is large, high reflectivity is achieved while helping to reduce the physical thickness of the film stack.

[0120] In some possible implementations, the absolute value of the difference between the refractive indexes of the adjacent two film layers of at least one of the film stacks in the reflection film 60 is greater than or equal to 0.6. In this way, when the number of film layers is fixed, the reflectivity of the film stack for the light of the central wavelength to be reflected can be further improved, which helps to improve the reflectivity of the reflection film 60 for light.

[0121] For example, as shown in FIG. 6, the absolute value of the difference between the refractive indexes of the adjacent two film layers of each of the four film stacks of the reflection film 60 is greater than or equal to 0.6. However, in some implementations, the absolute value of the difference between the refractive indexes of the adjacent two film layers of a part of the four film stacks of the reflection film 60 can be set to be greater than or equal to 0.6 and the absolute value of the difference between the refractive indexes of the adjacent two film layers of another part of the four film stacks can be set to be less than 0.6.

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

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

[0124] For example, as shown in FIG. 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 layer 611 and a second layer 612 with different refractive indexes, the second film stack 62 includes a third layer 621 and a fourth layer 622 with different refractive indexes, the third film stack 63 includes a fifth layer 631 and a sixth layer 632 with different refractive indexes, and the fourth film stack 64 includes a seventh layer 641 and an eighth layer 642 with different refractive indexes.

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

[0126] The material of each layer in the film stack is not limited herein. In some implementations, the refractive index of each layer in the film stack is greater than or equal to 1.6, in other words, the film stack can be formed by at least two high-refractive-index materials. In other implementations, the refractive index of each layer in the film stack is less than 0.6, in other words, the film stack can be formed by at least two low-refractive-index materials. In yet other implementations, the refractive index of some of the layers in the film stack is greater than or equal to 1.6 and the refractive index of some other layers is less than 1.6, in other words, the film stack can be formed by 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 layer in each of the film stacks in the reflective film 60 is greater than or equal to 1.6, so that each of the film stacks in the reflective film 60 is formed by high-refractive-index materials.

[0128] In some possible implementation manners, 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 the part of the film stacks in the reflective film 60 are all composed of high-refractive-index materials, and the other part of the film stacks are all composed of high-refractive-index materials and low-refractive-index materials.

[0129] In some possible implementation manners, the refractive index of each film layer of each film stack in the reflective film 60 is less than 1.6, so that each film stack in the reflective film 60 is composed of low-refractive-index materials.

[0130] In some possible implementation manners, the refractive index of each film layer of each film stack in the reflective film 60 is less than 1.6, so that each film stack in the reflective film 60 is composed of low-refractive-index materials.

[0131] In some possible implementation manners, the refractive index of each film layer of each film stack in the reflective film 60 is less than 1.6, so that each film stack in the reflective film 60 is composed of low-refractive-index materials.

[0132] It should be noted that whether each film layer belongs to which film stack can be determined by the refractive index of the film layer and the thickness change of the plurality of film layers. Of course, whether each film layer belongs to which film stack can also be determined by other manners.

[0133] Exemplarily, as shown in FIG. 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 is composed of first film layers 611 and second film layers 612 with different refractive indexes, the plurality of first film layers 611 have the same thickness, and the plurality of second film layers 612 have the same thickness. The second film stack 62 is composed of third film layers 621 and fourth film layers 622 with different refractive indexes, the plurality of third film layers 621 have the same thickness, and the plurality of fourth film layers 622 have the same thickness. The third film stack 63 is composed of fifth film layers 631 and sixth film layers 632 with different refractive indexes, the plurality of fifth film layers 631 have the same thickness, and the plurality of sixth film layers 632 have the same thickness. The fourth film stack 64 is composed of seventh film layers 641 and eighth film layers 642, the plurality of seventh film layers 641 have the same thickness, and the plurality of eighth film layers 642 have the same thickness. It can be learned that in the same film stack, the film layers with the same refractive index have the same thickness. Therefore, whether each film layer belongs to which film stack can be determined by the thickness change of the film layer.

[0134] Wherein, due to the error in the film layer manufacturing, the thickness of the film layer with the same refractive index in the same film stack is not completely the same, and there can be a certain error. Exemplarily, the thickness of the film layer with the same refractive index is considered to be the same film stack when the thickness fluctuation is less than or equal to ±5%, and is considered to be different film stack when the thickness fluctuation exceeds the range.

[0135] In the embodiments of the present application, the thickness of the film layer is not limited herein. Wherein, the thickness of the film layer can 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, the thickness of the film layer with a refractive index greater than or equal to 1.6 in the at least one film stack is greater than or equal to 80 nm and less than or equal to 150 nm. It can be understood that setting the thickness of the film layer with a refractive index greater than or equal to 1.6 to be 80 nm to 150 nm means that the thickness of the high refractive index material is limited to 80 nm to 150 nm. In this way, when the number of layers of the film layer is certain, the reflectivity of the film stack can be further improved.

[0137] In some possible implementations, the thickness of the film layer with a refractive index less than 1.6 in the at least one film stack is greater than or equal to 100 nm and less than or equal to 180 nm. It can be understood that setting the thickness of the film layer with a refractive index less than 1.6 to be 100 nm to 180 nm means that the thickness of the low refractive index material is limited to 100 nm to 180 nm. In this way, when the number of layers of the film layer is certain, the reflectivity of the film stack can be further improved.

[0138] In the above, the reflective film 60 is a dielectric film, at this time, the dielectric film is composed of a plurality of film stacks arranged in layers, as shown in FIG. 6. However, in some implementations, the reflective film 60 can also be a metal film, at this time, the metal film is also composed of a plurality of film stacks arranged in layers. In yet some implementations, the reflective film 60 can also be a metal-dielectric film, at this time, as shown in FIG. 11, the metal-dielectric film includes a metal layer 66 and a dielectric layer 65, the dielectric layer 65 is composed of a plurality of film stacks arranged in layers, and the dielectric layer 65 is used to be arranged between the metal layer 66 and the prism 50. Wherein, FIG. 11 is a schematic view of another cross-section of a reflective film provided by the embodiments 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 characteristics, which can improve the dispersion problem, so 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 well balance the transmittance and the dispersion problem, achieve high transmittance, and improve or solve the dispersion problem.

[0140] The multiple reflection films 60 in the turning element 11 are of the same type, for example, as shown in FIG. 4, both of the reflection films 60 are dielectric films. However, the turning element 11 can also have multiple reflection films 60 of different types.

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

[0142] In some other implementations, a first portion of the multiple reflection films 60 in the turning element 11 can be set as dielectric films, a second portion of the reflection films 60 can be set as metal films, and a third portion of the reflection films 60 can be set as metal-dielectric films. For example, when the number of the reflection films 60 is three, the first reflection film 60 is a dielectric film, the second reflection film 60 is a metal film, and the third reflection film 60 is a metal-dielectric film.

[0143] In some other implementations, a first portion of the multiple reflection films 60 in the turning element 11 can be set as dielectric films, a second portion of the reflection films 60 can be set as metal films, and a third portion of the reflection films 60 can be set as metal-dielectric films. For example, when the number of the reflection films 60 is three, the first reflection film 60 is a dielectric film, the second reflection film 60 is a metal film, and the third reflection film 60 is a metal-dielectric film.

[0144] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connecting” should be understood in a broad sense, for example, can be fixed connection, can be indirect connection through an intermediate medium, can be internal connection of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0145] In the embodiments of the present application or the devices or elements implied by the embodiments of the present application must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the embodiments of the present application. In the description of the embodiments of the present application, the meaning of “multiple” is two or more, unless otherwise specified and limited.

[0146] The terms "first", "second", "third", "fourth" etc. (if any) in the description and claims of the present application and above drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the embodiments of the present application described herein can be implemented, for example, in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0147] The term "a plurality of" herein refers to two or more. The term "and / or" herein is only a description of the association relationship between the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " herein generally represents that the associated objects before and after are in an "or" relationship; in the formula, the character " / " represents that the associated objects before and after are in a "division" relationship.

[0148] It can be understood that various numerical numbers involved in the embodiments of the present application are only distinguished for convenience of description, and are not used to limit the scope of the embodiments of the present application.

Claims

1. A reflective film, characterized by, The plurality of film stacks are stacked together; The optical thickness of any two adjacent film stacks is different, and the adjacent film stacks are used to reflect light of different central wavelengths, and the reflectivity of each film stack to the reflected light of the central wavelength is greater than or equal to 80%, each film stack comprises a plurality of film layers stacked together, and the refractive index of any two adjacent film layers is different.

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

6.

3. The reflective film according to claim 1 or 2, characterized in that, 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, wherein The refractive index of each film layer of at least one film stack is greater than or equal to 1.

6.

5. The reflective film according to any one of claims 1 to 4, wherein The refractive index of each film layer of at least one film stack is less than 1.

6.

6. The reflective film according to any one of claims 1 to 5, wherein The refractive index of a part of the film layers of at least one film stack is greater than or equal to 1.6, and the refractive index of another part of the film layers is less than 0.

6.

7. The reflective film according to any one of claims 1 to 6, wherein The thickness of the film layer with a refractive index greater than or equal to 1.6 in at least one film stack 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 film stack 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, wherein At least two film stacks comprise two film layers with different refractive indices.

10. The reflective film according to any one of claims 1 to 9, wherein The optical thickness of any two adjacent film stacks is different.

11. The reflective film according to any one of claims 1 to 10, wherein 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 comprises a metal layer and a dielectric layer formed by the plurality of film stacks.

12. A deflection element characterized by, The plurality of reflective films as claimed in any one of claims 1 to 11 and a prism are provided; The prism has a plurality of non-total reflection surfaces for reflecting light, and each non-total reflection surface is provided with one reflective film; The number of film stacks of any two adjacent reflective films is the same, and along the path of light passing through the plurality of non-total reflection surfaces, in adjacent two 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 of λ2, the λ1 and the λ2 are the same, 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 positive integers, and m is the number of film stacks of each reflective film.

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

14. The folding element according to claim 12 or 13, characterized in that Each reflective film is a dielectric film or a metal film.

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

16. A camera module, comprising: The plurality of reflective films as claimed in any one of claims 1 to 11 and a prism are provided; The lens and the image sensor are arranged on the same side of the folding element, or the lens and the image sensor are arranged on opposite sides of the folding element, respectively.

17. An electronic device, comprising: The camera module as claimed in claim 16 and a housing are provided, and the camera module is mounted in the housing.

Images