Prism assembly and camera module

Abstract

The application discloses a prism assembly, which comprises a base, a prism body arranged in the base, and an extinction layer. The prism body comprises an incident surface, an exit surface, a first reflecting surface, a second reflecting surface, and a third reflecting surface. The third reflecting surface is arranged in parallel with the incident surface and the exit surface. The first reflecting surface and the second reflecting surface are respectively arranged at two ends of the third reflecting surface in an inclined manner. The extinction layer is arranged at one end of the third reflecting surface away from the incident surface, and is used for absorbing invalid light rays that are emitted from the third reflecting surface, so as to avoid the invalid light rays from being reflected by the base and re-entering the prism body to participate in imaging. The application further discloses a camera module comprising the prism assembly.

Description

Technical Field

[0001] This utility model relates to the field of optical imaging technology, and in particular to a prism assembly and a camera module. Background Technology

[0002] In multi-stage folding telephoto periscope camera modules, such as those employing a four- or five-reflector optical module, a set of folding optical path structures is typically used to achieve long optical path transmission within a limited thickness. Prism components, as key optical elements, are used to reflect light multiple times to achieve a compact optical path layout. Prism components usually include an incident surface, an exit surface, and multiple reflecting surfaces. Utilizing the total internal reflection effect, externally incident light is sequentially reflected within the prism before entering the image sensor, thereby enabling high-magnification zoom and image acquisition.

[0003] However, in practical applications, while prism structures reflect effective imaging light, they may also introduce some ineffective or stray light into the imaging path, creating interference signals. Since the reflection inside the prism mainly relies on the total internal reflection mechanism at the interface between light and the medium, when light propagates from inside the prism (optically denser medium) to air (optically less dense medium), if the angle of incidence is less than the critical angle, partial transmission will occur, causing some ineffective light to pass through the prism.

[0004] Furthermore, the module structure typically requires the prism to be mounted tightly inside the base, and the surface of this base usually has a certain reflectivity. When the aforementioned transmitted ineffective light encounters the base structure, it is reflected back into the prism and, without effective control, re-enters the main imaging optical path, eventually reaching the image sensor. This manifests as imaging stray light, ghosting, and decreased contrast, severely impacting the module's imaging quality and user experience. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a prism assembly that can effectively suppress imaging stray light problems caused by invalid light transmission and reflection, thereby improving the imaging quality and optical stability of the periscope camera module.

[0006] This utility model provides a prism assembly, including a base, a prism body disposed within the base, and an extinction layer. The prism body includes an incident surface, an exit surface, a first reflecting surface, a second reflecting surface, and a third reflecting surface. The third reflecting surface is arranged parallel to the incident surface and the exit surface. The first reflecting surface and the second reflecting surface are respectively inclinedly disposed at both ends of the third reflecting surface. The extinction layer is disposed at the end of the third reflecting surface away from the incident surface, and is used to absorb invalid light transmitted from the third reflecting surface to prevent it from being reflected by the base and re-entering the prism body to participate in imaging.

[0007] In one embodiment, the incident surface and the exit surface are coplanar to form the top surface of the prism body, the third reflecting surface constitutes the bottom surface of the prism body, and the extinction layer includes a dielectric layer disposed on the bottom surface of the prism body. The dielectric layer is formed by stacking at least two optical materials with different refractive indices to adjust the critical angle of the third reflecting surface to enhance the total internal reflection effect of stray light.

[0008] In one embodiment, the matting layer further includes a reflective film layer disposed at the end of the dielectric layer away from the third reflective surface, for absorbing secondary reflected light from stray light.

[0009] In one embodiment, the reflective film is made of a low-reflectivity ink, film, or optical adhesive material.

[0010] In one embodiment, the angle between the first reflective surface and the second reflective surface and the third reflective surface is 40° to 55°.

[0011] In one embodiment, the prism body further includes a fourth reflecting surface disposed between the incident surface and the exit surface and coplanar with both, for relaying and reflecting light rays propagating along the folded light path.

[0012] In one embodiment, the first reflective surface, the second reflective surface, and the fourth reflective surface are all provided with a reflective coating to enhance the reflection effect on incident light.

[0013] In one embodiment, the reflective coating is an aluminum reflective film or a silver reflective film formed by vacuum evaporation.

[0014] This utility model also provides a camera module, including a lens module, an image sensor, and a prism assembly as described in the above embodiments. The prism assembly is used to guide the incident light captured by the lens module to the image sensor. The lens module and the image sensor are both disposed on the top surface of the prism body. The incident surface faces the lens module, and the exit surface faces the image sensor.

[0015] In one embodiment, the incident light enters from the incident surface of the prism assembly, undergoes multiple reflections within the prism assembly, and exits from the exit surface to the image sensor.

[0016] This invention provides a prism assembly with an extinction layer at the end of the third reflecting surface furthest from the incident surface. This layer absorbs ineffective light transmitted through the third reflecting surface, effectively preventing this light from being reflected back into the prism by the base or other structures and re-entering the imaging optical path. This significantly reduces stray light, ghosting, or blurring, improving image clarity and contrast. Furthermore, by arranging the third reflecting surface parallel to the incident and exit surfaces, combined with the first and second reflecting surfaces tilted at both ends, the invention ensures that the incident light forms a predetermined multiple reflection path inside the prism, thereby achieving stable control of the optical path reflection process and improving overall optical transmission efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the prism assembly provided in a preferred embodiment of this utility model.

[0019] Figure 2 A schematic diagram of the structure of the prism body provided in a preferred embodiment of this utility model.

[0020] Figure 3 A schematic diagram of the prism assembly provided in a preferred embodiment of this utility model.

[0021] Figure 4 This is a schematic diagram of the forming optical path of the prism assembly provided in a preferred embodiment of the present invention.

[0022] Figure label: 1. Prism body; 2. Base; 3. Extinction layer; 11. Incident surface; 12. Exit surface; 13. First reflecting surface; 14. Second reflecting surface; 15. Third reflecting surface; 16. Fourth reflecting surface; 31. Dielectric layer; 32. Reflective film layer. Detailed Implementation

[0023] The specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of this utility model. Based on the description of this utility model, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this utility model.

[0024] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0025] The terms “upper,” “lower,” “left,” “right,” “front,” “back,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of description and simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0026] The terms “first,” “second,” “third,” etc., are used merely to distinguish elements with similar properties, not to indicate or imply relative importance or a specific order.

[0027] The terms “include,” “comprising,” or any other variation thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0028] Please refer to Figure 1 This utility model provides a prism assembly including a base 2, a prism body 1, and an extinction layer 3 disposed on the prism body 1. The prism body 1 is installed inside the base 2 and is used to reflect incident light multiple times to achieve light path reversal. The base 2 is injection molded with the prism body 1 and the extinction layer 3 using a mold, and the base 2 has a fixing function. In another embodiment, it can be made of black anodized aluminum alloy or stainless steel with a light-absorbing coating on the surface, which not only serves a fixing function, but also has a certain light absorption function on its surface, which can reduce the refraction rate of internal stray light.

[0029] like Figure 2As shown, the cross-section of the prism body 1 is trapezoidal, comprising an incident surface 11, an exit surface 12, a third reflecting surface 15, a first reflecting surface 13, and a second reflecting surface 14. The top surface of the prism body 1 is located on the long side of the trapezoid and is formed by the incident surface 11 and the exit surface 12 coplanarly. Correspondingly, the bottom surface of the prism body 1 is located on the short side of the trapezoid and is formed by the third reflecting surface 15, which is arranged parallel to the incident surface 11 and the exit surface 12. The two ends of the prism body 1 are formed by the first reflecting surface 13 and the second reflecting surface 14. The first reflecting surface 13 and the second reflecting surface 14 are respectively inclinedly arranged at the two ends of the third reflecting surface 15. This can be understood as the first reflecting surface 13 and the second reflecting surface 14 being located on both sides of the prism body 1 and inclinedly connected to the top and bottom surfaces of the prism body 1, respectively. The first reflecting surface 13 and the second reflecting surface 14 are used to reflect the incident light. The extinction layer 3 is located on the bottom surface of the prism body 1 (i.e., the side of the prism body 1 facing the base 2) and is used to absorb the invalid light rays passing through the third reflecting surface 15. In traditional structures, this transmitted light is often reflected back into the prism by the bottom base 2 and other structures, mixing into the main imaging path and forming severe stray light. This solution effectively blocks this path by setting the extinction layer 3, controlling the generation of stray light from the source of the light path and improving image contrast and sharpness.

[0030] If the angle between the first reflecting surface 13, the second reflecting surface 14, and the third reflecting surface 15 is too large, the incident light may be transmitted during reflection due to the incident angle approaching or exceeding the critical angle. This causes some light to leak out from both ends of the prism body 1, failing to complete the complete reflection path. This reduces the energy utilization of the main optical path and increases the risk of stray light generated by reflection from the external structure of the prism, affecting imaging contrast and purity. Conversely, if the angle is set too small, the reflection path of the light inside the prism will become too concentrated, easily causing the reflection angle to be too small, beam overlap, or focus shift. This is not only detrimental to the spatial layout required for optical path folding but may also cause image plane skew, image distortion, or edge blurring, affecting the overall imaging quality. Therefore, in this embodiment, based on the refractive index of the prism material, the module spatial structure, and the reflection efficiency, the angle range is selected as 40° to 55° to ensure that the incident light propagates stably within the predetermined reflection path, while reducing light loss and stray shift, and improving imaging accuracy.

[0031] Optionally, the matting layer 3 includes a dielectric layer 31 bonded to the third reflecting surface 15 via a low-temperature bonding process. This low-temperature bonding process is performed at temperatures below 150°C. Surface activation treatment enables molecular-level bonding between the dielectric layer 31 and the bottom surface of the prism body 1, preventing deformation of the prism body 1 due to thermal stress or damage to the coating. The dielectric layer 31 is composed of two or more optical materials with different refractive indices, stacked to form a specific optical interference structure. For example, it can be composed of silicate glass with a refractive index of approximately 1.6 and high-refractive-index rare-earth glass with a refractive index of approximately 1.9, combined with a polymer optical adhesive (such as acrylic adhesive with a refractive index of 1.52) and a low-refractive-index dielectric film (such as a silicon dioxide film with a refractive index of approximately 1.46). This structure can adjust the critical angle, so that stray light that might otherwise be transmitted to the outside of the prism has its incident angle converted to a greater than the critical angle after refraction by the dielectric layer 31, resulting in total internal reflection at the third reflecting surface 15. This totally internalized stray light continues to propagate and reaches the base 2, where it is absorbed.

[0032] Furthermore, such as Figure 3 As shown, a reflective film layer 32 is attached to the end of the dielectric layer 31 away from the third reflective surface 15 to absorb the secondary reflection path of residual stray light. Specifically, in the above embodiment, stray light that has been totally reflected will continue to propagate and reach the base 2. The reflective film layer 32 disposed between the base 2 and the third reflective surface 15 performs weak reflection or dissipative reflection on this part of the stray light until it disappears, further enhancing the stray light suppression effect.

[0033] To improve the overall reflection efficiency of the prism assembly and reduce energy loss, both the first reflecting surface 13 and the second reflecting surface 14 are coated with a reflective layer to enhance the reflection capability of incident light in the main optical path and reduce energy attenuation caused by material boundary losses during reflection. Furthermore, to further extend the light reflection path and achieve longer optical path reversal within a limited module thickness, thereby compressing the camera module volume, the prism body 1 may also include a fourth reflecting surface 16 (e.g., [missing information]) disposed between the incident surface 11 and the exit surface 12, and coplanar with both. Figure 4 As shown in the figure, it is used to relay and reflect light, assisting in the return process after multiple angle jumps.

[0034] Specifically, the fourth reflective surface 16 can be designed as a continuous reflective surface, i.e., a single continuous reflective area to ensure complete reflection of light; or it can be designed as a partially reflected local reflective surface structure to reduce the coating area, lower manufacturing costs, and avoid interference or stray reflections caused by partial reflective areas. Regardless of the structural form adopted, the arrangement can be optimized in conjunction with the specific optical path design to ensure the stability of the propagation angle and path of light between the reflective surfaces, thereby ensuring reflection efficiency and imaging consistency.

[0035] The reflective coatings on each of the aforementioned reflective surfaces are all metal films formed by vacuum evaporation, such as aluminum or silver films. These metal materials have excellent reflective properties, achieving a reflectivity of over 90% in the visible light band, and possess good film adhesion and environmental stability, which helps ensure the reliable maintenance of the reflective performance of the prism assembly during long-term use. Through the synergistic effect of the multi-faceted reflective coatings, not only can optical utilization efficiency be significantly improved, but high-quality image acquisition results can also be achieved under compact structural conditions.

[0036] This embodiment of the invention also provides a camera module, which includes a lens module, an image sensor, and the aforementioned prism assembly. Both the lens module and the image sensor are disposed on the top surface of the prism body 1, with the incident surface 11 facing the lens module and the exit surface 12 facing the image sensor assembly.

[0037] The lens module collects light from the external scene and focuses it to the prism assembly, such as... Figure 4 As shown, incident light enters from the incident surface 11 and is reflected sequentially by the first reflecting surface 13, the fourth reflecting surface 16, the third reflecting surface 15, the fourth reflecting surface 16, and the second reflecting surface 14 inside the prism body 1, forming a refracted light path. Finally, it exits from the exit surface 12 to the image sensor. The image sensor converts the received light signal into an electrical signal to generate an image, completing the conversion from light signal to electrical signal. The incident light path undergoes five reflections within the prism body 1. While achieving light path refracting and compression, the prism assembly effectively suppresses internal stray light interference, ensuring image clarity and consistency, making it suitable for high-magnification zoom periscope camera systems.

[0038] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0039] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the appended claims.

Claims

1. A prism assembly, characterized in that, The device includes a base (2), a prism body (1) disposed within the base (2), and an extinction layer (3). The prism body (1) includes an incident surface (11), an exit surface (12), a first reflecting surface (13), a second reflecting surface (14), and a third reflecting surface (15). The third reflecting surface (15) is arranged parallel to the incident surface (11) and the exit surface (12). The first reflecting surface (13) and the second reflecting surface (14) are respectively inclined at both ends of the third reflecting surface (15). The extinction layer (3) is disposed at the end of the third reflecting surface (15) away from the incident surface (11) and is used to absorb invalid light transmitted from the third reflecting surface (15) to prevent it from being reflected by the base (2) and re-entering the prism body (1) to participate in imaging.

2. The prism assembly as claimed in claim 1, characterized in that, The incident surface (11) and the exit surface (12) are coplanar to form the top surface of the prism body (1), the third reflecting surface (15) constitutes the bottom surface of the prism body (1), and the extinction layer (3) includes a dielectric layer (31) disposed on the bottom surface of the prism body (1). The dielectric layer (31) is formed by stacking at least two optical materials with different refractive indices and is used to adjust the critical angle of the third reflecting surface (15) to enhance the total internal reflection effect of stray light.

3. The prism assembly as described in claim 2, characterized in that, The matting layer (3) also includes a reflective film layer (32) disposed at the end of the dielectric layer (31) away from the third reflective surface (15) for absorbing secondary reflected light from stray light.

4. The prism assembly as described in claim 3, characterized in that, The reflective film layer (32) is made of low-reflectivity ink, film or optical adhesive material.

5. The prism assembly as claimed in claim 1, characterized in that, The angle between the first reflective surface (13) and the second reflective surface (14) and the third reflective surface (15) is 40° to 55°.

6. The prism assembly as claimed in claim 1, characterized in that, The prism body (1) also includes a fourth reflecting surface (16) disposed between the incident surface (11) and the exit surface (12) and coplanar with both, for relaying and reflecting light rays propagating along the folded light path.

7. The prism assembly as claimed in claim 6, characterized in that, The first reflective surface (13), the second reflective surface (14) and the fourth reflective surface (16) are all provided with a reflective coating to enhance the reflection effect on incident light.

8. The prism assembly as claimed in claim 7, characterized in that, The reflective coating is an aluminum reflective film or a silver reflective film formed by vacuum evaporation.

9. A camera module, characterized in that, The prism assembly includes a lens module, an image sensor, and a prism assembly as described in any one of claims 1-8, wherein the lens module and the image sensor are both disposed on the top surface of the prism body (1), the incident surface (11) is disposed facing the lens module, and the exit surface (12) is disposed facing the image sensor.

10. The camera module as described in claim 9, characterized in that, The incident light enters from the incident surface (11) of the prism assembly, undergoes multiple reflections inside the prism assembly, and then exits from the exit surface (12) to the image sensor.

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