A long-focus camera module

Abstract

The application discloses a long-focus camera module, which sequentially comprises a first lens group assembly, a second lens group assembly and a return prism assembly from an object side to an image side; the first lens group assembly sequentially comprises a first lens, a second lens and a third lens; the first lens has positive refractive power; the second lens has negative refractive power and is a double-concave lens; the third lens has positive refractive power and is a double-convex lens or a meniscus lens; the second lens group assembly comprises a fourth lens; the fourth lens has positive refractive power and is a double-convex lens; the return prism assembly comprises an entrance surface, a first reflection surface, a total reflection surface, a second reflection surface and an exit surface; an imaging surface, the first lens group assembly and the second lens group assembly are all located on the same side of the return prism assembly. The long-focus camera module realizes long-focus function, keeps small volume and has good anti-shake performance.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a telephoto camera module. Background Technology

[0002] With the rapid development of mobile communication technology and the widespread adoption of smartphones, the functions and application scenarios of mobile phone cameras are constantly being enriched and expanded. Among them, telephoto camera modules, as functional modules capable of long-distance shooting and optical zoom, have received widespread attention in the smartphone market.

[0003] However, existing telephoto camera modules are quite large due to their long focal length and the resulting increased travel of the OIS (Optical Image Stabilizer). Therefore, developing a new telephoto camera module is of great significance. Summary of the Invention

[0004] In view of the above problems, the purpose of this invention is to provide a telephoto camera module that achieves telephoto functionality while maintaining a small size and having good image stabilization performance.

[0005] This invention provides a telephoto camera module, which includes, from the object side to the image side, a first lens group assembly, a second lens group assembly, and a folding prism assembly. The first lens group assembly includes, from the object side to the image side, a first lens, a second lens, and a third lens. The first lens has positive optical power; the second lens has negative optical power and is a biconcave lens; the third lens has positive optical power and is a biconvex lens or a meniscus lens. The second lens group assembly includes a fourth lens; the fourth lens has positive optical power and is a biconvex lens. The folding prism assembly includes an incident... The prism assembly comprises an incident surface, a first reflecting surface, a total reflection surface, a second reflecting surface, and an exiting surface. Light rays pass along a first optical axis through the first lens group assembly and the second lens group assembly, enter the prism assembly from the incident surface, are reflected by the first reflecting surface, are incident along the second optical axis to the total reflection surface, are reflected by the total reflection surface, are incident along the third optical axis to the second reflecting surface, are reflected by the second reflecting surface, and exit from the exiting surface to the imaging surface along the fourth optical axis. The imaging surface, the first lens group assembly, and the second lens group assembly are all located on the same side of the prism assembly.

[0006] Optionally, the first lens group assembly is moved in a direction perpendicular to the first optical axis by an image stabilization drive assembly for image stabilization compensation; and / or, the second lens group assembly is moved along the first optical axis by a focus drive assembly for autofocus.

[0007] Optionally, the total height HZ1 of the first lens group assembly, the second lens group assembly, and the folding prism assembly in the first optical axis direction, the total height HZ2 of the folding prism assembly and the imaging surface in the fourth optical axis direction, and the effective focal length EFL of the telephoto camera module satisfy: HZ1 < 0.7 EFL, HZ2 < 0.5 EFL.

[0008] Optionally, the operating F-number F.No of the lens of the telephoto camera module, and the total height HZ1 of the first lens group assembly, the second lens group assembly, and the folding prism assembly along the first optical axis direction satisfy: 0.3 <F.No / HZ1<2。

[0009] Optionally, the focal length f of the telephoto camera module and the focal length f1 of the first lens satisfy: 1.2 <f / f1<3。

[0010] Optionally, the center thickness CT1 of the first lens, the center thickness CT2 of the second lens, the center thickness CT3 of the third lens, and the center thickness CT4 of the fourth lens satisfy: 0.5 <CT1 / (CT2+CT3+CT4)<4.0。

[0011] Optionally, the center thickness CT1 of the first lens, the radius of curvature R11 of the object plane of the first lens, and the radius of curvature R12 of the image plane of the first lens satisfy: 5 < CT1 * (R12 / R11) < 30.

[0012] Optionally, the maximum effective diameter of the object side of the first lens DT11, the maximum effective diameter of the image side of the first lens DT12, the maximum effective diameter of the object side of the second lens DT21, and the maximum effective diameter of the image side of the second lens DT22 satisfy: 1≤(DT11+DT21) / (DT12 / DT22)<1.5.

[0013] Optionally, the total height HT1 of the first lens group assembly and the second lens group assembly along the first optical axis, and the total height HZ1 of the first lens group assembly, the second lens group assembly, and the folding prism assembly along the first optical axis, satisfy: 0.3 <HT1 / HZ1<0.8。

[0014] Optionally, the distance HT2 from the exit surface of the folding prism assembly to the image plane, and the total height HZ2 of the folding prism assembly and the imaging surface in the fourth optical axis direction satisfy: 0.1 < HT2 / HZ2 < 0.5.

[0015] The present invention also provides a terminal device, including the telephoto camera module described above.

[0016] The telephoto camera module provided by this invention comprises, from the object side to the image side, a first lens group assembly, a second lens group assembly, and a folding prism assembly. The first lens group assembly comprises, from the object side to the image side, a first lens, a second lens, and a third lens. The second lens group assembly includes a fourth lens. The folding prism assembly includes an incident surface, a first reflecting surface, a total reflection surface, a second reflecting surface, and an exit surface. The folding prism assembly enables three optical path reflections, achieving optical path folding and significantly reducing the overall height and shoulder height of the phone module. By rationally allocating the optical power, spacing, and refractive index of each lens, as well as the thickness and angle of the folding prism, a telephoto periscope function can be achieved while maintaining a small size. Movement of the first lens group assembly and / or the second lens group assembly in a direction perpendicular to the first optical axis can be used for image stabilization compensation, and movement along the first optical axis can be used for autofocus, resulting in excellent image stabilization performance. Specifically, it includes the following beneficial effects:

[0017] 1) Moving the first lens group assembly and / or the second lens group assembly in a direction perpendicular to the first optical axis can be used for image stabilization compensation, and moving it along the first optical axis can be used for autofocus. For example, moving the first lens group assembly in a direction perpendicular to the first optical axis can be used for image stabilization compensation, and moving the second lens group assembly along the first optical axis can be used for autofocus.

[0018] 2) The telephoto camera module can meet the size requirements of HZ1 < 0.7 EFL and HZ2 < 0.5 EFL, where HZ1 is the total height of the first lens group assembly, the second lens group assembly, and the folding prism assembly in the first optical axis direction, HZ2 is the total height of the folding prism assembly and the imaging surface in the fourth optical axis direction, and EFL is the effective focal length of the telephoto camera module, so as to control and reduce the height of the telephoto camera module, which is conducive to the miniaturization of the camera module.

[0019] 3) The angle of the folding prism assembly can be set to 25° < θ1 < 38°, 25° < θ2 < 38°, where θ1 is the angle between the incident surface and the first reflecting surface, and θ2 is the angle between the exit surface and the second reflecting surface, which can effectively balance the length and height of the folding prism.

[0020] 4) θ1 = θ2 can be set, where θ1 is the angle between the incident surface and the first reflecting surface, and θ2 is the angle between the exit surface and the second reflecting surface, which is beneficial for the processing and installation of the folding prism assembly. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention 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.

[0022] Figure 1 A schematic diagram of the front structure of the folded optical path of a telephoto camera module according to an embodiment of this application is shown.

[0023] Figure 2 A schematic diagram of the folded optical path structure of a telephoto camera module according to an embodiment of this application is shown.

[0024] Figure 3 A schematic diagram of the front structure of the folded optical path of the telephoto camera module according to Embodiment 1 of this application is shown;

[0025] Figures 4 to 11 The MTF curves of the telephoto camera module in Example 1 at infinity, at macro, and with OIS compensation are shown respectively, as well as the relative illumination and Y field of view diagram, field curvature diagram, distortion diagram, dot plot and lateral chromatic aberration diagram.

[0026] Figure 12 A schematic diagram of the front structure of the folded optical path of the telephoto camera module according to Embodiment 2 of this application is shown;

[0027] Figures 13 to 20 The MTF curves of the telephoto camera module in Embodiment 2 at infinity, at macro distance, at OIS compensation, relative illumination and Y field of view, field curvature, distortion, dot plot and lateral chromatic aberration are shown respectively. Detailed Implementation

[0028] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of preferred embodiments with reference to the accompanying drawings. Through the description of the specific embodiments, a more in-depth and specific understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the present invention; some well-known parts may not be shown. In the various drawings, the same elements are represented by similar reference numerals. For clarity, the various parts in the drawings are not necessarily drawn strictly to scale.

[0029] It is important to understand that the terms "first," "second," "third," "fourth," etc., are used merely to distinguish elements or circuits with similar properties, and do not indicate or imply relative importance or a specific order. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, which includes not only the listed elements but also other elements not expressly listed.

[0030] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0031] In this text, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane S13 is called the image-side surface of the lens.

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] Figure 1 A schematic diagram of the folded optical path front structure of a telephoto camera module according to an embodiment of this application is shown. Figure 2 A schematic diagram of the folded optical path structure of a telephoto camera module according to an embodiment of this application is shown. Please refer to... Figure 1 and Figure 2 The features, principles and other aspects of this application are described in detail below.

[0034] According to an exemplary embodiment of this application, a telephoto camera module comprises, sequentially from the object side to the image side, a first lens group assembly 1, a second lens group assembly 2, and a folding prism assembly 3. The first lens group assembly 1 comprises, sequentially from the object side to the image side, a first lens L1, a second lens L2, and a third lens L3; the first lens L1 has positive optical power; the second lens L2 has negative optical power and is a biconcave lens; the third lens L3 has positive optical power and is a biconvex lens or a meniscus lens; the second lens group assembly 2 includes a fourth lens L4; the fourth lens L4 has positive optical power and is a biconvex lens. The folding prism assembly 3 includes an incident surface P1, a first reflecting surface P2, a total reflection surface P3, a second reflecting surface P4, and an exit surface S10. Light rays pass through the first lens group assembly 1 and the second lens group assembly 2 along the first optical axis, enter the folding prism assembly 3 from the incident surface P1, are reflected by the first reflecting surface P2, and then pass along the second optical axis to the total reflection surface P3. After being reflected by the total reflection surface P3, the light rays pass along the third optical axis to the second reflecting surface P4. After being reflected by the second reflecting surface P4, the light rays exit from the exit surface S10 along the fourth optical axis to the imaging surface S13. The imaging surface S13, the first lens group assembly 1, and the second lens group assembly 2 are all located on the same side of the folding prism assembly 3.

[0035] Specifically, firstly, the light rays from the object side pass along the first optical axis through the first lens group assembly 1 and the second lens group assembly 2, that is, sequentially through the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4; wherein, the first lens L1 has positive optical power and can be spherical or aspherical, and the material can be glass or resin, etc.; the second lens L2 has negative optical power and is a meniscus lens; the third lens L3 has negative optical power and is a biconvex lens or a meniscus lens, used to correct aberrations; the fourth lens L4 has positive optical power and is used to converge the light rays, and the lens shape is a biconvex structure, wherein the convex surface of the object surface is beneficial to the overall size arrangement of the lens. Then, light enters the retroreflective prism assembly 3 from the incident surface P1, undergoes three reflections in sequence through the first reflecting surface P2, the total reflection surface P3, and the second reflecting surface P4, and exits from the exit surface S10 to the imaging surface S13. The imaging surface S13, the first lens group assembly 1, and the second lens group assembly 2 are all located on the same side of the retroreflective prism assembly 3. The retroreflective prism assembly 3 can be a retroreflective prism, such as a trapezoidal prism, which changes the original straight-line direction of the light. The back focal length of the lens can be folded inside the retroreflective prism assembly 3, so that the light emitted from the retroreflective prism assembly 3 can reach the imaging surface S13 after a shorter optical path, thereby shortening the back focal length of the lens and significantly reducing the overall height and shoulder height of the mobile phone module. By reasonably allocating the optical power, spacing, and refractive index of each lens, as well as the angle and thickness of the retroreflective prism assembly 3, the height of the camera module can be reduced to meet the thickness requirements of smartphones and other terminal devices. The lens is designed in a clustered structure. The first lens group assembly 1 and / or the second lens group assembly 2 are moved in a direction perpendicular to the first optical axis for image stabilization compensation. For example, when OIS image stabilization is enabled, the first lens group assembly 1 can be moved in a direction perpendicular to the first optical axis for image stabilization compensation, resulting in good image quality. The movement of the first lens group assembly 1 and / or the second lens group assembly 2 along the first optical axis allows for focusing from infinity to macro. For example, at infinity, the first lens group assembly 1 and the second lens group assembly 2 can focus at a small distance. When switching the object distance from infinity to macro, such as 40cm, the second lens group assembly 2 can be moved along the first optical axis, increasing the distance between the first lens group assembly 1 and the second lens group assembly 2 for macro focusing. Thus, the camera can focus from infinity to macro, achieving good image quality when shooting distant scenes and macro close-ups. Therefore, the telephoto camera module of this embodiment achieves telephoto periscope functionality while maintaining a small size and good image stabilization performance.

[0036] In an exemplary embodiment, according to the telephoto camera module of this application, the first lens group assembly 1 moves in a direction perpendicular to the first optical axis via an image stabilization drive assembly for image stabilization compensation; and / or, the second lens group assembly 2 moves along the first optical axis via a focusing drive assembly for autofocus. In one exemplary embodiment, focusing can be performed at object distances from 20cm to infinity via the second lens group assembly 2, and the focusing travel Z1 satisfies 0.3 < Z1 < 1mm. Therefore, a small change in travel can achieve a large change in focal length, which is beneficial for improving the focusing capability of the optical lens.

[0037] However, the present invention is not limited thereto. During image stabilization compensation, the image stabilization drive component can be used to drive at least one of the first lens group assembly 1, the second lens group assembly 2 and the imaging surface S13 to move in a direction perpendicular to the first optical axis; during autofocus, the focus drive component can also drive the first lens group assembly 1 to move along the first optical axis, both of which fall within the protection scope of the present invention.

[0038] In an exemplary embodiment, the telephoto camera module according to this application satisfies the following: HZ1 < 0.7 EFL, HZ2 < 0.5 EFL, where HZ1 is the total height of the first lens group assembly 1, the second lens group assembly 2, and the reflecting prism assembly 3 in the first optical axis direction, HZ2 is the total height of the reflecting prism assembly 3 and the imaging surface S13 in the fourth optical axis direction, and EFL is the effective focal length of the telephoto camera module. By satisfying HZ1 < 0.7 EFL and HZ2 < 0.5 EFL, and controlling the ratio of the total height HZ1 of the first lens group assembly 1, the second lens group assembly 2, and the reflecting prism assembly 3 in the first optical axis direction, the total height HZ2 of the reflecting prism assembly 3 and the imaging surface S13 in the fourth optical axis direction, to the effective focal length EFL of the telephoto camera module, the height of the telephoto camera module can be reduced, which is beneficial for miniaturizing the camera module.

[0039] In an exemplary embodiment, the telephoto camera module according to this application also includes an aperture stop STO. The aperture stop STO may be disposed, for example, between the first lens L1 and the second lens L2, or between other adjacent lenses, or on the object side of the first lens L1.

[0040] In an exemplary embodiment, the telephoto camera module according to this application further includes an IR filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface.

[0041] In an exemplary embodiment, the telephoto camera module according to this application has a first reflective surface P2 coated with a reflective film, and / or a second reflective surface P4 coated with a reflective film; the reflective film may be a metal film or a dielectric film, used to ensure that light is reflected and reduce the risk of being refracted out of the refracting prism assembly 3.

[0042] In an exemplary embodiment, for the telephoto camera module according to the present application, an antireflection film is coated on the incident surface P1, and / or an antireflection film is coated on the exit surface S10; which is used to reduce or eliminate the reflected light on the surface and ensure that there is sufficient light for better imaging.

[0043] In an exemplary embodiment, for the telephoto camera module according to the present application, the angles of the retroreflecting prism assembly 3 can be set as 25° < θ1 < 38° and 25° < θ2 < 38°, where θ1 is the angle between the incident surface P1 and the first reflecting surface P2, and θ2 is the angle between the exit surface S10 and the second reflecting surface P4, which can effectively balance the length and height of the retroreflecting prism assembly 3.

[0044] In one exemplary embodiment, θ1 = θ2, where θ1 is the angle between the incident surface P1 and the first reflecting surface P2, and θ2 is the angle between the exit surface S10 and the second reflecting surface P4, which is beneficial to the processing and installation of the retroreflecting prism assembly 3.

[0045] In an exemplary embodiment, for the telephoto camera module according to the present application, it can satisfy 0.3 < F.No / HZ1 < 2, where F.No is the working F-number of the lens of the telephoto camera module, and HZ1 is the total height of the first lens group assembly 1, the second lens group assembly 2, and the retroreflecting prism assembly 3 in the first optical axis direction. By controlling the ratio of the working F-number F.No of the lens of the telephoto camera module and the total height HZ1 of the first lens group assembly 1, the second lens group assembly 2, and the retroreflecting prism assembly 3 in the first optical axis direction, it can ensure that the lens assembly (i.e., the first lens group assembly 1 and the second lens group assembly 2) can receive a sufficient amount of light and guarantee the imaging quality.

[0046] In an exemplary embodiment, for the telephoto camera module according to the present application, it can satisfy 1.2 < f / f1 < 3, where f is the focal length of the telephoto camera module, and f1 is the focal length of the first lens L1. By controlling the ratio of the focal length f of the telephoto camera module and the focal length f1 of the first lens L1, a larger optical power can converge light and satisfy the focal length of the lens.

[0047] In an exemplary embodiment, the telephoto camera module according to the present application can satisfy 0.5 < CT1 / (CT2 + CT3 + CT4) < 4.0, where CT1 is the central thickness of the first lens L1, CT2 is the central thickness of the second lens L2, CT3 is the central thickness of the third lens L3, and CT4 is the central thickness of the fourth lens L4. By satisfying 0.5 < CT1 / (CT2 + CT3 + CT4) < 4.0 and controlling the ratio of the central thickness CT1 of the first lens L1, the central thickness CT2 of the second lens L2, the central thickness CT3 of the third lens L3, and the central thickness CT4 of the fourth lens L4, the central thickness CT1 of the first lens L1 is relatively large, which is beneficial for converging light and controlling the total height of the first lens group component 1 and the second lens group component 2.

[0048] In an exemplary embodiment, the telephoto camera module according to the present application can satisfy 5 < CT1 * (R12 / R11) < 30, where CT1 is the central thickness of the first lens L1, R11 is the curvature radius of the object surface of the first lens L1, and R12 is the curvature radius of the image surface of the first lens L1. By satisfying 5 < CT1 * (R12 / R11) < 30 and controlling the ratio of the central thickness CT1 of the first lens L1, the curvature radius R11 of the object surface of the first lens L1, and the curvature radius R12 of the image surface of the first lens L1, it is beneficial for controlling the smooth convergence of light.

[0049] In an exemplary embodiment, the telephoto camera module according to the present application can satisfy 1 ≤ (DT11 + DT21) / (DT12 / DT22) < 1.5, where DT11 is the maximum effective diameter of the object side of the first lens L1, DT12 is the maximum effective diameter of the image side of the first lens L1, DT21 is the maximum effective diameter of the object side of the second lens L2, and DT22 is the maximum effective diameter of the image side of the second lens L2. By satisfying 1 ≤ (DT11 + DT21) / (DT12 / DT22) < 1.5 and controlling the maximum effective diameter DT11 of the object side of the first lens L1, the maximum effective diameter DT12 of the image side of the first lens L1, the maximum effective diameter DT21 of the object side of the second lens L2, and the maximum effective diameter DT22 of the image side of the second lens L2, it is beneficial to avoid problems such as astigmatism, distortion, and chromatic aberration and ensure the imaging quality.

[0050] In an exemplary embodiment, for the telephoto camera module according to the present application, 0.3 < HT1 / HZ1 < 0.8 can be satisfied, where HT1 is the total height of the first lens group component 1 and the second lens group component 2 in the first optical axis direction, and HZ1 is the total height of the first lens group component 1, the second lens group component 2, and the folding prism component 3 in the first optical axis direction. Satisfying 0.3 < HT1 / HZ1 < 0.8 helps to reasonably allocate the height by controlling the ratio of the total height HT1 of the first lens group component 1 and the second lens group component 2 in the first optical axis direction to the total height HZ1 of the first lens group component 1, the second lens group component 2, and the folding prism component 3 in the first optical axis direction.

[0051] In an exemplary embodiment, for the telephoto camera module according to the present application, 0.1 < HT2 / HZ2 < 0.5 can be satisfied, where HT2 is the distance from the exit surface S10 of the folding prism component 3 to the image plane, and HZ2 is the total height of the folding prism component 3 and the imaging surface S13 in the fourth optical axis direction. Satisfying 0.1 < HT2 / HZ2 < 0.5 can control the module shoulder height located at the imaging surface S13 by controlling the ratio of the distance HT2 from the exit surface S10 of the folding prism component 3 to the image plane to the total height HZ2 of the folding prism component 3 and the imaging surface S13 in the fourth optical axis direction.

[0052] In an exemplary embodiment, for the telephoto camera module according to the present application, GT3 > 0.4 mm can be satisfied, where GT3 is the air gap between the third lens L3 and the fourth lens L4. Satisfying GT3 > 0.4 mm can be used to ensure the stroke space during focusing by controlling the size of the air gap GT3 between the third lens L3 and the fourth lens L4.

[0053] In an exemplary embodiment, for the telephoto camera module according to the present application, GT4 > 0.4 mm can be satisfied, where GT4 is the air gap between the fourth lens L4 and the entrance surface P1 of the folding prism component 3. Satisfying GT4 > 0.4 mm can be used to ensure the stroke space during focusing by controlling the size of the air gap GT4 between the fourth lens L4 and the entrance surface P1 of the folding prism component 3.

[0054] In an exemplary embodiment, for the telephoto camera module according to the present application, 0.7 < EFL / BFL < 1.1 can be satisfied, where EFL is the effective focal length of the telephoto camera module and BFL is the distance from the last image-side surface of the fourth lens L4 to the imaging surface S13. Satisfying 0.7 < EFL / BFL < 1.1 can help to obtain an appropriate depth of field and better image resolution, and ensure the imaging quality by controlling the ratio of the effective focal length EFL of the telephoto camera module to the distance BFL from the image-side surface of the fourth lens L4 to the imaging surface S13.

[0055] In an exemplary embodiment, the telephoto camera module according to this application satisfies 11mm < CT5 < 120mm, where CT5 is the equivalent prism thickness of the folding prism assembly 3. By controlling the size of the equivalent prism thickness CT5 of the folding prism assembly 3, the back focal length of the lens can be controlled within the folding prism assembly 3, allowing light emitted from the folding prism assembly 3 to reach the imaging surface S13 after a shorter optical path, thus correspondingly shortening the back focal length of the lens.

[0056] In an exemplary embodiment, the telephoto camera module according to this application satisfies 2.8mm < CT6 < 4mm, where CT6 is the thickness of the prism after the folded optical path of the folding prism assembly 3. By controlling the size of the prism thickness CT6 after the folded optical path of the folding prism assembly 3, the overall height and shoulder height of the camera module can be significantly reduced, thus satisfying 2.8mm < CT6 < 4mm.

[0057] In an exemplary embodiment, the telephoto camera module according to this application satisfies 1.55≤n1≤1.1.98; 45≤V1≤90, where n1 is the refractive index of the first lens L1 and V1 is the dispersion coefficient of the first lens L1. Satisfying 1.55≤n1≤1.1.98; 45≤V1≤90, controlling the refractive index n1 and dispersion coefficient V1 of the first lens L1, helps reduce the burden of correcting chromatic aberration for other lenses and leaves room for freedom in correcting other aberrations.

[0058] In an exemplary embodiment, the telephoto camera module according to this application can be assembled as an integral part of the driving component and the imaging component (i.e., the first lens group component 1, the second lens group component 2 and the folding prism component 3) or assembled separately.

[0059] In an exemplary embodiment, according to the telephoto camera module of this application, the incident surface P1, the first reflecting surface P2, the second reflecting surface P4, the total reflection surface P3 and the exit surface S10 of the folding prism assembly 3 suppress stray light influence by means of ink coating, screen printing and other methods, and the screen printing area is defined by a light spot with a short side of 0.7F and a long side of 0.9F as the boundary.

[0060] In an exemplary embodiment, according to the telephoto camera module of this application, the folding prism assembly 3 can be in the form of two prisms bonded together or a single prism with a slot.

[0061] In an exemplary embodiment, the telephoto camera module according to this application can have its folding prism assembly 3 modified by chamfering or rounding corners. The chamfered and rounded corners are treated with coating, screen printing, or other methods to suppress stray light, which helps to improve the reliability of the module and reduce stray light.

[0062] In an exemplary embodiment, the telephoto camera module according to this application, when adapted to a 1 / 2.8” chip, has a chip body height of only 2.8mm on the imaging surface S13 of the mobile phone camera, which is extremely suitable for foldable phones and is an important telephoto architecture for foldable phones.

[0063] In an exemplary embodiment, the telephoto camera module according to this application has a chip disposed on the imaging surface S13, the lens architecture can achieve 3-6x optical zoom, and the chip size can be adapted to all chip sizes below 1 / 1.56”.

[0064] In an exemplary embodiment, the telephoto camera module according to this application, based on a 1 / 2” chip, can achieve a body height of less than 6.1mm for the mobile phone camera and a shoulder height of less than 5.3mm on the imaging surface S13, thus making full use of the space of the mobile phone back cover decorative parts.

[0065] Based on the same inventive concept, the terminal device according to the exemplary embodiments of this application includes the aforementioned telephoto camera module. The terminal device includes, but is not limited to, smartphones, tablets, laptops, gimbal cameras, surveillance cameras, and other imaging devices. Implementation of this terminal device can be found in the embodiments of the telephoto camera module; repeated details will not be elaborated further.

[0066] However, those skilled in the art will understand that the number of lenses constituting the optical imaging lens can be varied to obtain the various results and advantages described herein without departing from the technical solutions claimed in this application. For example, although four lenses are described as an example in the embodiments, the optical imaging lens is not limited to including four lenses. If desired, the optical imaging lens may also include other numbers of lenses.

[0067] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the telephoto camera module applicable to the above-described embodiments.

[0068] Example 1

[0069] The following is for reference Figure 3 This application describes a telephoto camera module according to Embodiment 1 of this application. Figure 3 A schematic diagram of the folded optical path front structure of a telephoto camera module according to Embodiment 1 of this application is shown.

[0070] The telephoto camera module of Embodiment 1 includes, from the object side to the image side, a first lens group assembly 1, a second lens group assembly 2, and a folding prism assembly 3. The first lens group assembly 1 includes, from the object side to the image side, a first lens L1, a second lens L2, and a third lens L3. The second lens group assembly 2 includes a fourth lens L4. The first lens L1 to the fourth lens L4 can all be aspherical, and each includes an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through. The imaging surface S13, the first lens group assembly 1, and the second lens group assembly 2 are all located on the same side of the folding prism assembly 3. An aperture stop can be disposed between the first lens L1 and the second lens L2. A filter IR can be disposed between the exit surface S10 and the imaging surface S13 of the folding prism assembly 3.

[0071] The first lens L1 has positive optical power, with a convex object-side surface and a concave image-side surface. The second lens L2 has negative optical power and is a biconcave lens, with both its object-side and image-side surfaces being concave. The third lens L3 has positive optical power and is either a biconvex lens or a meniscus lens, for example, a meniscus lens, with a convex object-side surface and a concave image-side surface. The fourth lens L4 has positive optical power and is a biconvex lens, with both its object-side and image-side surfaces being convex. The folding prism assembly 3 includes an incident surface P1, a first reflecting surface P2, a total reflection surface P3, a second reflecting surface P4, and an exit surface S10. The light rays pass along the first optical axis through the first lens group assembly 1 and the second lens group assembly 2, that is, sequentially through the first lens L1, the aperture, the second lens L2, the third lens L3 and the fourth lens L4; then, they enter the folding prism assembly 3 from the incident surface P1, are reflected by the first reflecting surface P2, and are incident along the second optical axis to the total reflection surface P3. After being reflected by the total reflection surface P3, they are incident along the third optical axis to the second reflecting surface P4. After being reflected by the second reflecting surface P4, they are emitted from the exit surface S10 along the fourth optical axis, and after passing through the filter IR, they are finally imaged on the imaging surface S13.

[0072] Table 1 shows the basic parameters of the telephoto camera module of Embodiment 1 at infinity, where the units for radius of curvature, thickness / distance, focal length, and half-aperture are all millimeters (mm).

[0073] Table 1:

[0074]

[0075] Wherein, S1 represents the object-side surface of the first lens L1, S2 represents the image-side surface of the first lens L1, S3 represents the aperture STO, S4 represents the object-side surface of the second lens L2, S5 represents the image-side surface of the second lens L2, S6 represents the object-side surface of the third lens L3, S7 represents the image-side surface of the third lens L3, S8 represents the object-side surface of the fourth lens L4, S9 represents the image-side surface of the fourth lens L4, S10 represents the exit surface of the folding prism assembly 3, S11 represents the object-side surface of the filter IR, S12 represents the image-side surface of the filter IR, and S13 represents the imaging surface.

[0076] Table 2 shows the relevant parameters of the telephoto camera module of Embodiment 1, which are focused by moving only the second lens group assembly 2 at infinity object distance, 30 cm object distance and OIS stabilization at infinity object distance. In the table, H1 represents the distance between the third lens L3 and the fourth lens L4 in millimeters (mm), H2 represents the distance between the fourth lens L4 and the incident surface P1 of the folding prism assembly 3 in millimeters (mm), θ1 represents the offset angle of the first lens group assembly 1, and S1 represents the compensation displacement of the first lens group assembly 1 perpendicular to the first optical axis.

[0077] Table 2:

[0078] INF 30CM OIS H1 4.59E-01 1.44E-01 4.59E-01 H2 3.97E-01 7.12E-01 3.97E-01 θ1 0 0 1 S1 0 0 -0.16

[0079] In Embodiment 1, the object-side surface and image-side surface of any one of the first lens L1 to the fourth lens L4 can both be even-order aspherical surfaces, and the surface shape of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0080]

[0081] Where Z represents the height along the optical axis, c is the reciprocal of the surface radius, k is the conic coefficient, and r is the aperture along the radial direction; α represents the aspherical coefficient, α1 represents the aspherical coefficient A2, α2 represents the aspherical coefficient A4, and so on. Table 3 gives the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for each aspherical mirror in Example 1.

[0082] Table 3:

[0083]

[0084] In Example 1, the telephoto camera module has a focal length f of 11.16mm, an operating wavelength of 430-650nm, an aperture of F.No. 2.7, an imaging circle diameter of 6.65mm, a field of view of 31.4°, and a total optical length of 16.3mm. The focal length f1 of the first lens L1 is 5.07mm, so f / f1 = 2.20. The center thickness CT1 of the first lens L1 is 0.71mm, and the sum of the center thicknesses of the second lens L2 to the fourth lens L4 is CT2 + CT3 + CT4 = 0.22 + 0.522 + 0.529 = 1.271mm, so CT1 / (CT2 + CT3 + CT4) = 0.56. The center thickness CT1 of the first lens L1 is 0.71 mm. The radius of curvature of the object plane of the first lens L1 is R11 = 4.82 mm, and the radius of curvature of the image plane of the first lens L1 is R12 = 73.55 mm. Therefore, CT1*(R12 / R11) = 10.83. The maximum effective diameter of the object plane of the first lens L1 is DT11 = 2.11 mm, and the maximum effective diameter of the image plane of the first lens L1 is DT12 = 2.11 mm. The maximum effective diameter of the object plane of the second lens L2 is DT21 = 1.81 mm, and the maximum effective diameter of the image plane of the second lens L2 is DT22 = 1.81 mm. Therefore, (DT11+DT21) / (DT12 / DT22) = 1.

[0085] Figure 4 The MTF curve of the telephoto camera module of Embodiment 1 at infinity object distance is shown. The MTF curve shows the transmission of image details (i.e. image contrast) at different spatial frequencies of the imaging system. The MTF value is greater than 0.2 at a spatial frequency of 250 lp / mm, indicating good imaging effect. Figure 5 The MTF curve of the telephoto camera module in Embodiment 1 at macro distance is shown. The MTF value is greater than 0.1 at a spatial frequency of 250 lp / mm, indicating good imaging effect. Figure 6 The MTF curve of the telephoto camera module in Embodiment 1 during OIS compensation is shown. Its MTF value is greater than 0.05 at a spatial frequency of 250 lp / mm, indicating good imaging effect. Figure 7 The diagram shows the relative illumination and Y-field angle of the telephoto camera module in Embodiment 1. The relative illumination is greater than 75%, and the image brightness is uniform. Figure 8 The field curvature diagram of the telephoto camera module of Embodiment 1 is shown. The field curvature is less than ±0.1mm, indicating good correction. Figure 9 The distortion diagram of the telephoto camera module of Embodiment 1 is shown. The absolute value of the distortion is less than 1.0%, indicating good correction. Figure 10The diagram shows a dot plot of the telephoto camera module of Embodiment 1, with a scale of ±20µm, that is, the scale range in the horizontal and vertical directions is ±20µm (various aberration corrections are very good, and the overall aberration of the system is very small). Figure 11 The diagram shows the chromatic aberration of the telephoto camera module in Embodiment 1. It illustrates the focal deviation of different wavelengths of light along the optical axis on the focal plane when the pupil radius is 2.1550 mm, with a chromatic aberration of less than 0.02 mm and good color reproduction. According to... Figures 4 to 11 It can be seen that the telephoto camera module given in Example 1 can achieve good imaging quality.

[0086] Example 2

[0087] The following is for reference Figure 12 This application describes a telephoto camera module according to Embodiment 2. For the sake of brevity, descriptions similar to those in Embodiment 1 are omitted in this embodiment. Figure 12 A schematic diagram of the folded optical path front structure of a telephoto camera module according to Embodiment 2 of this application is shown.

[0088] The telephoto camera module of Embodiment 2 includes, from the object side to the image side, a first lens group assembly 1, a second lens group assembly 2, and a folding prism assembly 3. The first lens group assembly 1 includes, from the object side to the image side, a first lens L1, a second lens L2, and a third lens L3. The second lens group assembly 2 includes a fourth lens L4. The first lens L1 to the fourth lens L4 can all be aspherical, and each includes an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through. The imaging surface S13, the first lens group assembly 1, and the second lens group assembly 2 are all located on the same side of the folding prism assembly 3. An aperture stop can be disposed between the first lens L1 and the second lens L2. A filter IR can be disposed between the exit surface S10 and the imaging surface S13 of the folding prism assembly 3.

[0089] The first lens L1 has positive optical power, with a convex object-side surface and a concave image-side surface. The second lens L2 has negative optical power and is a biconcave lens, with both its object-side and image-side surfaces being concave. The third lens L3 has positive optical power and is either a biconvex lens or a meniscus lens, for example, a meniscus lens, with a convex object-side surface and a concave image-side surface. The fourth lens L4 has positive optical power and is a biconvex lens, with both its object-side and image-side surfaces being convex. The folding prism assembly 3 includes an incident surface P1, a first reflecting surface P2, a total reflection surface P3, a second reflecting surface P4, and an exit surface S10. The light rays pass along the first optical axis through the first lens group assembly 1 and the second lens group assembly 2, that is, sequentially through the first lens L1, the aperture, the second lens L2, the third lens L3 and the fourth lens L4; then, they enter the folding prism assembly 3 from the incident surface P1, are reflected by the first reflecting surface P2, and are incident along the second optical axis to the total reflection surface P3. After being reflected by the total reflection surface P3, they are incident along the third optical axis to the second reflecting surface P4. After being reflected by the second reflecting surface P4, they are emitted from the exit surface S10 along the fourth optical axis, and after passing through the filter IR, they are finally imaged on the imaging surface S13.

[0090] Table 4 shows the basic parameters of the telephoto camera module of Example 2 at infinity, where the units for radius of curvature, thickness / distance, focal length, and half-aperture are all millimeters (mm).

[0091] Table 4:

[0092]

[0093] Table 5 shows the relevant parameters of the telephoto camera module of Embodiment 2, which are achieved by focusing only by moving the second lens group assembly 2 at object distances of infinity, 30 cm, and OIS stabilization at infinity. In the table, H1 represents the distance between the third lens L3 and the fourth lens L4 in millimeters (mm), H2 represents the distance between the fourth lens L4 and the incident surface P1 of the folding prism assembly 3 in millimeters (mm), θ1 represents the offset angle of the first lens group assembly 1, and S1 represents the compensation displacement of the first lens group assembly 1 perpendicular to the first optical axis.

[0094] Table 5:

[0095] IN F 30CM OIS H1 2.98E-01 1.68E-01 2.98E-01 H2 6.97E-01 1.05E+00 6.97E-01 θ1 0 0 1 S1 0 0 -0.16

[0096] Table 6 shows the higher-order coefficients that can be used for each aspherical mirror in Example 2, wherein each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0097] Table 6:

[0098] Face number A4 A6 A8 A10 A12 A14 A16 S4 3.99E-02 -9.11E-03 3.02E-03 -8.71E-04 1.75E-04 -1.95E-05 8.87E-07 S5 2.44E-02 -7.13E-03 2.93E-03 5.57E-04 -4.93E-04 2.85E-05 1.34E-05 S6 1.97E-02 -8.19E-03 4.02E-03 -4.08E-04 -5.38E-05 -8.58E-05 2.58E-05 S7 3.84E-02 -5.19E-03 2.38E-03 -1.55E-03 5.37E-04 -9.24E-05 6.00E-06 S8 -2.47E-03 4.18E-04 4.51E-04 -5.05E-04 1.99E-04 -3.67E-05 2.64E-06 S9 -2.19E-03 1.41E-03 -6.33E-04 1.42E-04 -1.07E-05 -1.92E-06 3.14E-07

[0099] The telephoto camera module has a focal length f of 11.16mm, an operating wavelength of 430-650nm, an aperture of F.No. 2.7, an imaging circle diameter of 6.65mm, a field of view of 31.4°, and a total optical length of 16.3mm. The focal length f1 of the first lens L1 is 5.15mm, so f / f1 = 2.17. The center thickness CT1 of the first lens L1 is 0.905mm. The sum of the center thicknesses of the second lens L2 to the fourth lens L4, CT2 + CT3 + CT4 = 0.186 + 0.538 + 0.64 = 1.364mm, therefore CT1 / (CT2 + CT3 + CT4) = 0.66. The center thickness CT1 of the first lens L1 is 0.905 mm. The radius of curvature of the object plane of the first lens L1 is R11 = 4.96 mm, and the radius of curvature of the image plane of the first lens L1 is R12 = 94.3 mm. Therefore, CT1*(R12 / R11) = 17.21. The maximum effective diameter of the object plane of the first lens L1 is DT11 = 2.14 mm, and the maximum effective diameter of the image plane of the first lens L1 is DT12 = 2.00 mm. The maximum effective diameter of the object plane of the second lens L2 is DT21 = 1.79 mm, and the maximum effective diameter of the image plane of the second lens L2 is DT22 = 1.64 mm. Therefore, (DT11+DT21) / (DT12 / DT22) = 1.08.

[0100] Figure 13 The MTF curve of the telephoto camera module in Example 2 at infinity is shown. The MTF (Modulation Transfer Function) curve shows the transmission of image details (i.e. image contrast) at different spatial frequencies by the imaging system. The MTF value is greater than 0.1 at a spatial frequency of 250 lp / mm, indicating good imaging effect. Figure 14 The MTF curve of the telephoto camera module in Embodiment 2 at macro distance is shown. Its MTF value is greater than 0.05 at a spatial frequency of 250 lp / mm, indicating good imaging effect. Figure 15 The MTF curve of the telephoto camera module in Embodiment 2 during OIS compensation is shown. Its MTF value is greater than 0.1 at a spatial frequency of 250 lp / mm, indicating good imaging effect. Figure 16 The diagram shows the relative illumination and Y-field angle of the telephoto camera module in Embodiment 2. The relative illumination is greater than 75%, and the image brightness is uniform. Figure 17 The field curvature diagram of the telephoto camera module of Embodiment 2 is shown. The field curvature is less than ±0.1mm, indicating good correction. Figure 18 The distortion diagram of the telephoto camera module of Embodiment 2 is shown. The absolute value of the distortion is less than 1.0%, indicating good correction. Figure 19The diagram shows a dot plot of the telephoto camera module of Embodiment 2, with a scale of ±20µm, that is, the scale range in the horizontal and vertical directions is ±20µm (various aberration corrections are very good, and the overall aberration of the system is very small). Figure 20 The diagram shows the chromatic aberration of the telephoto camera module in Embodiment 2. It illustrates the focal deviation of different wavelengths of light along the optical axis on the focal plane when the pupil radius is 2.1550 mm, with a chromatic aberration of less than 0.04 mm and good color reproduction. According to... Figures 13 to 20 It can be seen that the telephoto camera module given in Example 2 can achieve good imaging quality.

[0101] In summary, Examples 1 and 2 satisfy the relationships shown in Table 7.

[0102] Table 7:

[0103]

[0104] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A telephoto camera module, characterized in that, The assembly includes, in sequence from the object side to the image side, a first lens group assembly, a second lens group assembly, and a folding prism assembly; The first lens group assembly includes a first lens, a second lens, and a third lens sequentially from the object side to the image side; the first lens has positive optical power; the second lens has negative optical power and is a biconcave lens; the third lens has positive optical power and is a biconvex lens or a meniscus lens. The second lens group assembly includes a fourth lens; the fourth lens has positive optical power and is a biconvex lens; The catadioptric prism assembly includes an incident surface, a first reflecting surface, a total reflection surface, a second reflecting surface, and an exit surface. The incident surface of the catadioptric prism assembly is positioned opposite to the exit surface of the second lens group assembly. Light rays pass through the first lens group assembly and the second lens group assembly along a first optical axis, enter the catadioptric prism assembly from the incident surface, are reflected by the first reflecting surface, are incident on the total reflection surface along a second optical axis, are reflected by the total reflection surface, are incident on the second reflecting surface along a third optical axis, are reflected by the second reflecting surface, and are exited from the exit surface onto the imaging surface along a fourth optical axis. The imaging surface, the first lens group assembly, and the second lens group assembly are all located on the same side of the catadioptric prism assembly.

2. The telephoto camera module according to claim 1, characterized in that, The first lens group assembly moves in a direction perpendicular to the first optical axis via an image stabilization drive assembly for image stabilization compensation; and / or, the second lens group assembly moves along the first optical axis via a focus drive assembly for autofocus.

3. The telephoto camera module according to claim 1, characterized in that, The total height HZ1 of the first lens group assembly, the second lens group assembly, and the folding prism assembly in the first optical axis direction, the total height HZ2 of the folding prism assembly and the imaging surface in the fourth optical axis direction, and the effective focal length EFL of the telephoto camera module satisfy: HZ1 < 0.7 EFL, HZ2 < 0.5 EFL.

4. The telephoto camera module according to claim 1, characterized in that, The operating F-number F.No of the lens of the telephoto camera module, and the total height HZ1 of the first lens group assembly, the second lens group assembly, and the folding prism assembly along the first optical axis direction, satisfy: 0.

3. <F.No / HZ1<2。 5. The telephoto camera module according to claim 1, characterized in that, The focal length f of the telephoto camera module and the focal length f1 of the first lens satisfy: 1.2 <f / f1<3。 6. The telephoto camera module according to claim 1, characterized in that, The center thickness CT1 of the first lens, the center thickness CT2 of the second lens, the center thickness CT3 of the third lens, and the center thickness CT4 of the fourth lens satisfy: 0.5 <CT1 / (CT2+CT3+CT4)<4.0。 7. The telephoto camera module according to claim 1, characterized in that, The center thickness CT1 of the first lens, the radius of curvature R11 of the object plane of the first lens, and the radius of curvature R12 of the image plane of the first lens satisfy: 5 < CT1 * (R12 / R11) < 30.

8. The telephoto camera module according to claim 1, characterized in that, The maximum effective diameter of the object side of the first lens DT11, the maximum effective diameter of the image side of the first lens DT12, the maximum effective diameter of the object side of the second lens DT21, and the maximum effective diameter of the image side of the second lens DT22 satisfy: 1≤(DT11+DT21) / (DT12 / DT22)<1.

5.

9. The telephoto camera module according to claim 1, characterized in that, The total height HT1 of the first lens group assembly and the second lens group assembly along the first optical axis, and the total height HZ1 of the first lens group assembly, the second lens group assembly, and the folding prism assembly along the first optical axis, satisfy: 0.3 <HT1 / HZ1<0.8。 10. The telephoto camera module according to claim 1, characterized in that, The distance HT2 from the exit surface of the folding prism assembly to the image plane, and the total height HZ2 of the folding prism assembly and the imaging surface in the fourth optical axis direction satisfy: 0.1 < HT2 / HZ2 < 0.5.

Images