Reduced height mobile phone telephoto lens

Abstract

The application discloses a height-reduced mobile phone long-focus lens, which sequentially comprises, from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens, a prism and an image plane; the first lens has positive refractive power; the second lens has positive refractive power; the third lens has positive refractive power; the fourth lens has negative refractive power; the prism has an incident surface, a first reflecting surface, a total reflecting surface, a second reflecting surface and an emitting surface; light emitted from the fourth lens is incident into the prism from the incident surface, is reflected at least once by the first reflecting surface, the total reflecting surface and the second reflecting surface, and is emitted from the emitting surface to the image plane. The height-reduced mobile phone long-focus lens can realize a large aperture, a small size, a long-focus section and high imaging quality.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a telephoto lens for mobile phones with reduced height. Background Technology

[0002] With the development of mobile phone camera modules, the use cases for telephoto lenses in mobile phones are gradually increasing, and telephoto has become an indispensable part of mobile phone telephoto lenses. However, due to the space limitations of mobile phones and the requirements of long optical path, conventional periscope lenses cannot meet the requirements of telephoto lenses to balance focal length, large aperture, and small size. There is a situation where the longer the focal length, the larger the aperture and the thicker the required mobile phone module, which makes it impossible to use telephoto large aperture lenses in mobile phones. Summary of the Invention

[0003] In view of the above problems, the purpose of this invention is to provide a telephoto lens for mobile phones with reduced height, which can achieve a large aperture, small size, long focal length and high image quality.

[0004] This invention provides a telephoto lens for mobile phones with reduced height, comprising a first lens, a second lens, a third lens, a fourth lens, a prism, and an image plane; wherein, the first lens has positive optical power; the second lens has positive optical power; the third lens has positive optical power; the fourth lens has negative optical power; the prism has an incident surface, a first reflecting surface, a total reflection surface, a second reflecting surface, and an exit surface, wherein light rays emitted from the fourth lens enter the prism from the incident surface, are reflected at least once by the first reflecting surface, the total reflection surface, and the second reflecting surface, and then exit the image plane via the exit surface.

[0005] Optionally, the light rays emitted from the fourth lens are incident into the prism along the first optical axis, reflected by the first reflecting surface to the total reflection surface along the second optical axis, reflected again by the total reflection surface to the second reflecting surface along the third optical axis, reflected again by the second reflecting surface to the exiting surface along the fourth optical axis, and then exiting the image plane through the exiting surface.

[0006] 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, the center thickness CT4 of the fourth lens, the spatial gap T1 between the first lens and the second lens, the spatial gap T2 between the second lens and the third lens, and the spatial gap T3 between the third lens and the fourth lens satisfy: CT1+CT2+CT3+CT4+T1+T2+T3<3.3mm.

[0007] Optionally, the air gap T4 between the fourth lens and the prism satisfies: 0.33mm < T4 < 0.55mm.

[0008] Optionally, the effective focal length f of the telephoto lens of the mobile phone and the distance BFL from the image plane of the fourth lens to the image plane satisfy: 0.7 < f / BFL < 1.

[0009] Optionally, the effective focal length f of the telephoto lens of the mobile phone, the effective focal length f2 of the second lens, and the effective focal length f4 of the fourth lens satisfy: 0 < ((f / f4) - (f / f2)) < 3.

[0010] Optionally, the thickness CT5 of the prism satisfies: 11mm < CT5 < 14mm.

[0011] 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: 19 < (DT11 + DT21) / (DT12 / DT22) < 21.

[0012] Optionally, the thickness CT6 of the prism after folding the optical path and the total length L1 of the prism after optical conversion satisfy: 0.2 < CT6 / L1 < 0.3.

[0013] The height-reduced telephoto lens for mobile phones provided by this invention, through reasonable allocation of optical power, can achieve focusing and imaging within a range of 25cm to infinity using a 1 / 2.76″ telephoto lens. It can achieve excellent image quality at both 25cm and infinity. Furthermore, by combining multiple lenses and prisms into an L-shaped periscope architecture to fully utilize space, it achieves a telephoto optical lens design with a large aperture, small size, and long focal length. The optical design has a low shoulder height, making it suitable for lightweight foldable phones. The height-reduced telephoto lens for mobile phones provided by this invention can achieve the following beneficial effects:

[0014] 1) A 72mm equivalent focal length high-definition telephoto lens was designed, which achieves good image quality from 25cm to infinity when the aperture is large at F2.6.

[0015] 2) The optical design has a shoulder height of 3.08mm, which is a perfect fit for the design of slim and lightweight folding phones;

[0016] 3) The lens body is 7.5mm high, making full use of the space in the decorative parts of the phone back cover. Attached Figure Description

[0017] 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.

[0018] Figure 1 An equivalent lens structure diagram of a telephoto lens for a mobile phone with reduced height according to an embodiment of this application is shown.

[0019] Figure 2 An equivalent lens structure diagram of a telephoto lens for a mobile phone with reduced height according to an embodiment of this application is shown.

[0020] Figure 3 An equivalent structure diagram of a telephoto lens for a mobile phone with reduced height according to Embodiment 1 of this application is shown.

[0021] Figures 4 to 8 The MTF curve, relative illumination and Y field of view, distortion diagram, light fan diagram and lateral chromatic aberration diagram of the telephoto lens of the mobile phone with reduced height in Example 1 are shown respectively.

[0022] Figure 9 A diagram showing the equivalent structure of a telephoto lens for a mobile phone with reduced height according to Embodiment 2 of this application is provided.

[0023] Figures 10 to 14 The MTF curve, relative illumination and Y field of view, distortion diagram, light fan diagram and lateral chromatic aberration diagram of the telephoto lens of the mobile phone with reduced height in Example 2 are shown respectively. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shape of the sphere shown in the drawings is illustrated by way of example. That is, the shape of the sphere is not limited to that shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.

[0027] In this article, 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 plane of the lens, and the surface of each lens closest to the image plane is called the image plane of the lens.

[0028] 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.

[0029] The features, principles and other aspects of this application are described in detail below.

[0030] like Figure 1 As shown, the telephoto lens for a mobile phone with reduced height according to an exemplary embodiment of this application, along the optical axis from the object side to the image side, sequentially includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a prism G5, and an image plane IMG; wherein, the first lens G1 has positive optical power; the second lens G2 has positive optical power; the third lens G3 has positive optical power; the fourth lens G4 has negative optical power; the prism G5 has an incident surface, a first reflecting surface, a total reflection surface, a second reflecting surface, and an exit surface (…). Figure 1 Not shown, please refer to Figure 2 The light rays emitted from the fourth lens G4 enter the prism G5 from the incident surface, are reflected at least once by the first reflecting surface, the total reflection surface, and the second reflecting surface, and then exit the image plane IMG through the exit surface.

[0031] In this embodiment, the optical power of the telephoto lens for mobile phones with reduced height follows a positive-positive-positive-negative arrangement, which is beneficial for correcting spherical aberration and chromatic aberration. The third lens G3 can be a double concave lens, meaning that both its object and image surfaces are concave. The light emitted from the fourth lens G4 enters the prism G5 from the incident surface, is reflected at least once by the first reflecting surface, the total internal reflection surface, and the second reflecting surface, and then exits through the exit surface to the image plane IMG. This folds the back focal length inside the prism G5, shortening the lens's back focal length and reducing the camera height. By rationally allocating the optical power of each lens, a 1 / 2.76″ telephoto lens can be used to achieve focusing and imaging within a range from 25cm to infinity, providing excellent image quality at both 25cm and infinity. By combining multiple lenses with the prism G5 into an L-shaped periscope architecture to fully utilize space, a telephoto optical lens design with a large aperture, small size, and long focal length is achieved. The optical design has a small shoulder height, making it suitable for lightweight folding phones.

[0032] In an exemplary implementation, reference may be made to Figure 2 According to the telephoto lens of the mobile phone with reduced height according to this application, the light rays emitted from the fourth lens G4 are incident on the prism G5 along the first optical axis, reflected by the first reflecting surface to the total reflection surface along the second optical axis, reflected again by the total reflection surface to the second reflecting surface along the third optical axis, reflected again by the second reflecting surface to the exiting surface along the fourth optical axis, and then exiting onto the image plane IMG.

[0033] In one exemplary embodiment, according to the height-reduced telephoto lens of the present application, the angle θ1 between the first optical axis and the second optical axis satisfies 0° < θ1 < 90°; the angle θ2 between the second optical axis and the third optical axis satisfies 90° < θ2 < 180°; and the angle θ3 between the third optical axis and the fourth optical axis satisfies 0° < θ3 < 90°. Furthermore, in one exemplary embodiment, according to the height-reduced telephoto lens of the present application, the first optical axis and the fourth optical axis are parallel.

[0034] In one exemplary embodiment, the reduced-height telephoto lens for mobile phones according to this application has a common plane for the incident surface, the total internal reflection surface, and the exit surface. In another exemplary embodiment, the reduced-height telephoto lens for mobile phones according to this application has a trapezoidal prism G5, where the incident surface, the total internal reflection surface, and the exit surface can be jointly disposed on the longer base edge of the trapezoidal prism, and the first and second reflecting surfaces can be respectively disposed on the two sides of the trapezoidal prism.

[0035] In an exemplary embodiment, the telephoto lens for mobile phones with reduced height according to this application has one or more of the first reflective surface, the total reflection surface, and the second reflective surface coated with a reflective film, which can ensure that light can be completely reflected and reduce the risk of light being refracted out of the prism G5.

[0036] In an exemplary embodiment, the reduced-height telephoto lens for mobile phones according to this application satisfies CT1+CT2+CT3+CT4+T1+T2+T3<3.3mm; wherein the center thickness of the first lens G1 is CT1, the center thickness of the second lens G2 is CT2, the center thickness of the third lens G3 is CT3, the center thickness of the fourth lens G4 is CT4, the spatial gap between the first lens G1 and the second lens G2 is T1, the spatial gap between the second lens G2 and the third lens G3 is T2, and the spatial gap between the third lens G3 and the fourth lens G4 is T3. Satisfying CT1+CT2+CT3+CT4+T1+T2+T3<3.3mm, by controlling the center thicknesses CT1-CT4 of the first lens G1 to the fourth lens G4 and the air gaps T1-T3 between the lenses, facilitates the miniaturization of the mobile phone telephoto lens.

[0037] In an exemplary embodiment, the reduced-height telephoto lens for mobile phones according to this application satisfies 0.33mm < T4 < 0.55mm; wherein, the air gap between the fourth lens G4 and the prism G5 is T4. Satisfying 0.33mm < T4 < 0.55mm, by controlling the air gap T4 between the fourth lens G4 and the prism G5, facilitates the miniaturization of the mobile phone telephoto lens.

[0038] In an exemplary embodiment, the telephoto lens for a lower-height mobile phone according to this application satisfies 0.7 < f / BFL < 1; wherein, the effective focal length of the telephoto lens for a lower-height mobile phone is f, and the distance from the image plane of the fourth lens G4 to the image plane IMG is BFL. Satisfying 0.7 < f / BFL < 1 means that by controlling the effective focal length f of the telephoto lens for a lower-height mobile phone and the distance BFL from the image plane of the fourth lens G4 to the image plane IMG, if the value of f / BFL is less than the lower limit, astigmatism, distortion, etc., may occur; if the value of f / BFL is greater than the upper limit, it may lead to insufficient lens resolution, affecting image quality; and a suitable value of f / BFL can be used to achieve excellent image quality from object distances from 25cm to infinity.

[0039] In an exemplary embodiment, the telephoto lens for mobile phones with reduced height according to this application satisfies 1 < ((f / f4) + (f / f2)) < 4; wherein, the effective focal length of the telephoto lens for mobile phones with reduced height is f, the effective focal length of the second lens G2 is f2, and the effective focal length of the fourth lens G4 is f4. By satisfying 1 < ((f / f4) + (f / f2)) < 4, and by controlling the effective focal length f of the telephoto lens for mobile phones with reduced height, the effective focal length f2 of the second lens G2, and the effective focal length f4 of the fourth lens G4, suitable focal lengths and depths of field can be obtained, avoiding astigmatism, distortion, and chromatic aberration, and enabling excellent imaging quality from object distances from 25cm to infinity.

[0040] In an exemplary embodiment, the reduced-height telephoto lens for mobile phones according to this application satisfies 0 < ((f / f4) - (f / f2)) < 3; wherein, the effective focal length of the reduced-height telephoto lens is f, the effective focal length of the second lens G2 is f2, and the effective focal length of the fourth lens G4 is f4. By satisfying 0 < ((f / f4) - (f / f2)) < 3, and by controlling the effective focal length f of the reduced-height telephoto lens, the effective focal length f2 of the second lens G2, and the effective focal length f4 of the fourth lens G4, suitable focal lengths and depths of field can be obtained, avoiding astigmatism, distortion, and chromatic aberration, and enabling excellent imaging quality from object distances from 25cm to infinity.

[0041] In an exemplary implementation, reference may be made to Figure 1 According to this application, the reduced-height telephoto lens for mobile phones satisfies 11mm < CT5 < 14mm; wherein, the thickness CT5 of the prism G5 satisfies 11mm < CT5 < 14mm. By controlling the thickness CT5 of the prism G5, the optical path of light inside the prism G5 can be adjusted, allowing the light to be correctly focused on the image plane IMG, thereby improving image quality.

[0042] In an exemplary embodiment, the reduced-height telephoto lens for mobile phones according to this application can satisfy...

[0043] 1.55≤n1≤1.98, and 45≤V1≤90; where the refractive index of the first lens G1 is n1, and the dispersion coefficient of the first lens G1 is V1. By satisfying 1.55≤n1≤1.98 and 45≤V1≤90, the chromatic aberration of the first lens G1 can be controlled through its refractive index n1 and dispersion coefficient V1, reducing the burden of chromatic aberration correction on other lenses and leaving room for correction of other aberrations.

[0044] In an exemplary embodiment, the telephoto lens for mobile phones with reduced height according to this application satisfies 19 < (DT11 + DT21) / (DT12 / DT22) < 21; wherein, the maximum effective object-side diameter of the first lens G1 is DT11, the maximum effective image-side diameter of the first lens G1 is DT12, the maximum effective object-side diameter of the second lens G2 is DT21, and the maximum effective image-side diameter of the second lens G2 is DT22. By satisfying 19 < (DT11 + DT21) / (DT12 / DT22) < 21, and by controlling the maximum effective object-side diameter DT11, the maximum effective image-side diameter DT12 of the first lens G1, the maximum effective object-side diameter DT21 of the second lens G2, and the maximum effective image-side diameter DT22 of the second lens G2, a balance between increasing light intake and reducing aberrations can be achieved, thereby improving image quality.

[0045] In an exemplary implementation, reference may be made to Figure 2According to this application, the reduced-height telephoto lens for mobile phones satisfies 0.2 < CT6 / L1 < 0.3; wherein, the thickness of the prism G5 after folding the optical path is CT6, and the total length is L1. By satisfying 0.2 < CT6 / L1 < 0.3, and by controlling the thickness CT6 and the total length L1 of the prism G5 after folding the optical path, the reflection of light at a specific angle inside the prism G5 can be controlled, thereby controlling the thickness CT6 of the prism G5 after folding the optical path, which is beneficial for miniaturizing the telephoto lens for mobile phones.

[0046] In an exemplary embodiment, the reduced-height telephoto lens for mobile phones according to this application satisfies 31° < A < 35°; wherein, the angle after the prism G5 folds the optical path is A. Satisfying 31° < A < 35°, by controlling the angle A after the prism G5 folds the optical path, and thus controlling the thickness CT6 of the prism G5 after folding the optical path, it is beneficial to achieve miniaturization of the mobile phone telephoto lens.

[0047] In an exemplary embodiment, the reduced-height telephoto lens for mobile phones according to this application further includes an aperture stop STO, which is disposed between the first lens G1 and the second lens G2 to further improve overall performance. In other exemplary embodiments, the aperture stop STO may be disposed between other lenses.

[0048] In an exemplary embodiment, the telephoto lens for mobile phones with reduced height 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 image plane IMG.

[0049] 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.

[0050] The following describes in further detail, with reference to the accompanying drawings, a specific embodiment of a telephoto lens for mobile phones with reduced height that is applicable to the above-described embodiments.

[0051] Example 1

[0052] The following is for reference Figure 3 This application describes a telephoto lens for mobile phones with reduced height according to Embodiment 1. Figure 3 An equivalent structure diagram of a telephoto lens for a mobile phone with reduced height according to Embodiment 1 of this application is shown.

[0053] like Figure 3As shown, the telephoto lens of a mobile phone with reduced height includes, in order from the object side to the image side, a first lens G1, an aperture STO, a second lens G2, a third lens G3, a fourth lens G4, a prism G5, an IR filter, and an image plane IMG. Each of the first lens G1 to the fourth lens G4 includes an object-side surface that faces the object side and allows imaging light to pass through, and an image-side surface that faces the image side and allows imaging light to pass through.

[0054] The first lens G1 has positive optical power, with its object surface 11 being convex and its image surface 12 being convex. The second lens G2 has positive optical power, with its object surface 21 being concave and its image surface 22 being convex. The third lens G3 has positive optical power, with its object surface 31 being concave and its image surface 32 being concave. The fourth lens G4 has negative optical power, with its object surface 41 being convex and its image surface 42 being convex. The prism G5 is a trapezoidal prism, with an object surface 51 and an image surface 52. The filter IR has an object surface 61 and an image surface 62. Light from the object passes sequentially through the first lens G1, the aperture STO, the second lens G2, the third lens G3, the fourth lens G4, the prism G5, and the filter IR, and is finally imaged on the image plane IMG.

[0055] Table 1 shows the basic parameters of the reduced-height telephoto lens for mobile phones in Example 1, where the units for radius of curvature, thickness, focal length, and aperture are all millimeters (mm).

[0056] Table 1:

[0057]

[0058] In Example 1, the object and image surfaces of the first lens G1 are both standard surfaces, and the object and image surfaces of any one of the second to fourth lenses G4 are both extended aspherical surfaces. The surface shape of each extended aspherical surface can be defined using, but is not limited to, the following aspherical formula:

[0059] (1)

[0060] Where x is the distance vector from the vertex of the extended aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the extended aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the extended aspherical surface. Table 2 below shows the higher-order coefficients A4, A6, A8, A10, A12, A14 and A16 that can be used for each of the extended aspherical mirrors 21-42 in Example 1.

[0061] Table 2:

[0062]

[0063] In this embodiment, the focal length of the reduced-height mobile phone telephoto lens is 11.2mm, its operating wavelength is 430-650nm, its aperture is f / 2.65, its imaging circle diameter is 7mm, its field of view is 32.6°, and its total optical length is 17.04mm. The relationship between the center thicknesses CT1-CT4 of the first lens G1 to the fourth lens G4 and the air gaps T1-T3 between the lenses is CT1+CT2+CT3+CT4+T1+T2+T3=3.09mm. The relationship between the air gap T4 between the fourth lens G4 and the prism G5 is T4=0.5mm. The relationship between the effective focal length f of the mobile phone telephoto lens and the distance BFL from the image plane to the image plane of the fourth lens is f / BFL=0.8.

[0064] Figure 4 The diagram shows the MTF curve of the telephoto lens of the mobile phone with reduced height in Example 1. The MTF (Modulation Transfer Function) curve is the change in the degree to which the lens reproduces the details of the subject onto the image plane (IMG) as a function of spatial frequency. The MTF meets the design requirements, and the lens has good image quality. Figure 5 The diagram shows the relative illumination and Y-field of view of the telephoto lens of the mobile phone with reduced height in Example 1. The relative illumination is greater than 72%, and the brightness of the image is uniform. Figure 6 The distortion diagram of the reduced-height telephoto lens of the mobile phone in Example 1 is shown. The absolute value of the distortion is less than 0.2%, which is well corrected. Figure 7 The image shows the light field diagram of the reduced-height mobile phone telephoto lens of Example 1, with a scale of ±10μm. The imaging magnification error values ​​are all within an acceptable range. Figure 8 The diagram shows the transverse chromatic aberration of the telephoto lens for a mobile phone with reduced height according to Example 1. In the example, at a maximum field of view of 16.8000Deg, the focal deviation of different wavelengths of light formed on the imaging plane along a direction perpendicular to the optical axis is within 2.4μm, indicating good color reproduction. According to... Figures 4 to 8 It can be seen that the telephoto lens for mobile phones with reduced height given in Example 1 can achieve good image quality.

[0065] Example 2

[0066] The following is for reference Figure 9 This application describes a telephoto lens for mobile phones with reduced height according to Embodiment 2. Figure 9 An equivalent lens structure diagram of a reduced-height mobile phone telephoto lens according to Embodiment 2 of this application is shown. In this embodiment, for the sake of brevity, descriptions similar to those in Embodiment 1 are omitted.

[0067] like Figure 9 As shown, the telephoto lens of a mobile phone with reduced height includes, in order from the object side to the image side, a first lens G1, an aperture STO, a second lens G2, a third lens G3, a fourth lens G4, a prism G5, an IR filter, and an image plane IMG. Each of the first lens G1 to the fourth lens G4 includes an object-side surface that faces the object side and allows imaging light to pass through, and an image-side surface that faces the image side and allows imaging light to pass through.

[0068] The first lens G1 has positive optical power, with its object surface 11 being convex and its image surface 12 being convex. The second lens G2 has positive optical power, with its object surface 21 being convex and its image surface 22 being concave. The third lens G3 has positive optical power, with its object surface 31 being concave and its image surface 32 being concave. The fourth lens G4 has negative optical power, with its object surface 41 being convex and its image surface 42 being convex. The prism G5 is a trapezoidal prism, with an object surface 51 and an image surface 52. The filter IR has an object surface 61 and an image surface 62. Light from the object passes sequentially through the first lens G1, the aperture STO, the second lens G2, the third lens G3, the fourth lens G4, the prism G5, and the filter IR, and is finally imaged on the image plane IMG.

[0069] Table 3 shows the basic parameters of the reduced-height mobile phone telephoto lens of Example 2, where the units for radius of curvature, thickness, focal length, and aperture are all millimeters (mm).

[0070] Table 3:

[0071]

[0072] Table 4 shows the higher-order coefficients that can be used for each of the extended aspherical mirrors 21-42 in Example 2, wherein the surface shape of each of the extended aspherical mirrors 21-42 can be defined by the formula (1) given in Example 1 above.

[0073] Table 4:

[0074]

[0075] In this embodiment, the focal length of the reduced-height mobile phone telephoto lens is 11.6mm, its operating wavelength is 430-650nm, its aperture is f / 2.65, its imaging circle diameter is 7mm, its field of view is 31.6°, and its total optical length is 17.04mm. The relationship between the center thicknesses CT1-CT4 of the first lens G1 to the fourth lens G4 and the air gaps T1-T3 between the lenses is CT1+CT2+CT3+CT4+T1+T2+T3=3.10mm. The relationship between the air gap T4 between the fourth lens G4 and the prism G5 is T4=0.5mm. The relationship between the effective focal length f of the mobile phone telephoto lens and the distance BFL from the image plane to the image plane of the fourth lens is f / BFL=0.8.

[0076] Figure 10 The diagram shows the MTF curve of the telephoto lens of the mobile phone with reduced height in Example 2. The MTF (Modulation Transfer Function) curve is the change in the degree to which the lens reproduces the details of the subject onto the image plane (IMG) as a function of spatial frequency. The MTF meets the design requirements, and the lens has good image quality. Figure 11 The diagram shows the relative illumination and Y-field of view of the telephoto lens of the mobile phone with reduced height in Example 2. The relative illumination is greater than 70%, and the brightness of the image is uniform. Figure 12 The distortion diagram of the reduced-height mobile phone telephoto lens of Example 2 is shown. The absolute value of the distortion is less than 1%, indicating good correction. Figure 13 The image fan diagram of the reduced-height mobile phone telephoto lens of Example 2 is shown, with a scale of ±40μm. The imaging magnification error values ​​are all within an acceptable range. Figure 14 The diagram shows the transverse chromatic aberration of the telephoto lens for a mobile phone with reduced height in Example 2. In the example, at a maximum field of view of 3.6000 mm, the focal deviation of different wavelengths of light formed on the imaging plane along a direction perpendicular to the optical axis is shown, with a transverse chromatic aberration within 4 μm and good color reproduction. According to... Figures 10 to 14 It can be seen that the telephoto lens for mobile phones with reduced height given in Example 2 can achieve good image quality.

[0077] 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 lens for mobile phones with reduced height, characterized in that, The sequence from object to image includes: first lens, second lens, third lens, fourth lens, prism, and image plane; among which, The first lens has positive optical power; the second lens has positive optical power; the third lens has positive optical power; the fourth lens has negative optical power; the first lens to the fourth lens are arranged opposite to the incident surface of the prism; The prism has an incident surface, a first reflecting surface, a total reflection surface, a second reflecting surface, and an exit surface. The light rays emitted from the fourth lens enter the prism from the incident surface, are reflected at least once by the first reflecting surface, the total reflection surface, and the second reflecting surface, and then exit to the image plane through the exit surface.

2. The telephoto lens for mobile phones with reduced height according to claim 1, characterized in that, The light rays emitted from the fourth lens enter the prism along the first optical axis through the incident surface, are reflected by the first reflecting surface to the total reflection surface along the second optical axis, are reflected by the total reflection surface to the second reflecting surface along the third optical axis, are reflected by the second reflecting surface to the exiting surface along the fourth optical axis, and are then emitted from the exiting surface to the image plane.

3. The telephoto lens for mobile phones with reduced height 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, the center thickness CT4 of the fourth lens, the spatial gap T1 between the first lens and the second lens, the spatial gap T2 between the second lens and the third lens, and the spatial gap T3 between the third lens and the fourth lens satisfy: CT1+CT2+CT3+CT4+T1+T2+T3<3.3mm.

4. The mobile phone telephoto lens with reduced height according to claim 1, characterized in that, The air gap T4 between the fourth lens and the prism satisfies the condition: 0.33mm < T4 < 0.55mm.

5. The mobile phone telephoto lens with reduced height according to claim 1, characterized in that, The effective focal length f of the telephoto lens of the mobile phone and the distance BFL from the image plane of the fourth lens to the image plane satisfy: 0.7 < f / BFL < 1.

6. The mobile phone telephoto lens with reduced height according to claim 1, characterized in that, The effective focal length f of the telephoto lens of the mobile phone, the effective focal length f2 of the second lens, and the effective focal length f4 of the fourth lens satisfy: 1 ​​< ((f / f4) + (f / f2)) < 4.

7. The mobile phone telephoto lens with reduced height according to claim 1, characterized in that, The effective focal length f of the telephoto lens of the mobile phone, the effective focal length f2 of the second lens, and the effective focal length f4 of the fourth lens satisfy: 0 < ((f / f4) - (f / f2)) < 3.

8. The telephoto lens for mobile phones with reduced height according to claim 1, characterized in that, The thickness CT5 of the prism satisfies the following condition: 11mm < CT5 < 14mm.

9. The telephoto lens for mobile phones with reduced height 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: 19 < (DT11 + DT21) / (DT12 / DT22) < 21.

10. The telephoto lens for mobile phones with reduced height according to claim 1, characterized in that, The thickness CT6 of the prism after folding the optical path and the total length L1 of the prism after optical conversion satisfy: 0.2 < CT6 / L1 < 0.3.

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