External lens and imaging device

Abstract

The present invention provides an external lens and an imaging device. The external lens has a total of five lenses, which sequentially include, along the optical axis from the object side to the imaging surface: a first lens with a negative optical power, whose object side is convex and whose image side is concave; a second lens with a negative optical power, whose object side is convex and whose image side is concave; a third lens with a negative optical power, whose object side is concave and whose image side is convex; a fourth lens with a positive optical power, whose image side is convex; a fifth lens with a negative optical power, whose object side is concave and whose image side is convex; the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are cylindrical lenses; wherein, the total optical length TTL of the external lens and the effective focal length f of the external lens satisfy: -0.03 < TTL / f < 0. The external lens and the imaging device provided by the present invention can obtain picture information with a larger field of view, improve the aspect ratio of wide-screen imaging, and greatly improve the user experience effect.

Description

Technical Field

[0001] The present invention relates to the technical field of imaging lenses, and particularly to an external lens and an imaging device. Background Art

[0002] With the popularization of intelligent mobile devices such as smart phones, and in order to meet the pursuit of obtaining better shooting effects in different scenarios, the functions of imaging modules are constantly being improved and expanded. In order to obtain better shooting effects, an external lens is usually mounted at the lens of an electronic device. Since the external lens is configured, the aspect ratio of widescreen imaging can be increased. However, the field of view range is still small, and when shooting, the center of the captured image is clear, but the periphery of the image is relatively blurred; moreover, the resolution of existing external lenses is not high and cannot be matched with high-pixel imaging devices. Summary of the Invention

[0003] Aiming at the above problems, the purpose of the present invention is to provide an external lens and an imaging device, which have the characteristics of excellent imaging quality, can increase the aspect ratio of widescreen imaging, and greatly improve the user experience effect.

[0004] The technical solution adopted by the present invention is as follows:

[0005] An external lens, comprising a total of five lenses, which sequentially include, along the optical axis from the object side to the imaging surface: a first lens with a negative optical power, the object side surface of which is convex and the image side surface of which is concave;

[0006] A second lens with a negative optical power, the object side surface of which is convex and the image side surface of which is concave;

[0007] A third lens with a negative optical power, the object side surface of which is concave and the image side surface of which is convex;

[0008] A fourth lens with a positive optical power, the image side surface of which is convex;

[0009] A fifth lens with a negative optical power, the object side surface of which is concave and the image side surface of which is convex;

[0010] The first lens, the second lens, the third lens, the fourth lens and the fifth lens are cylindrical lenses;

[0011] Wherein, the optical total length TTL of the external lens and the effective focal length f of the external lens satisfy: -0.03 < TTL / f < 0.

[0012] Further preferably, the optical total length TTL of the external lens and the clear aperture radius d1 of the object side surface of the first lens satisfy: 0.88 < TTL / d1 < 0.97.

[0013] More preferably, the total optical length TTL of the external lens and the sum ∑CT of the central thicknesses of the first to fifth lenses along the optical axis satisfy: 0.5 < ∑CT / TTL < 0.54; the sum ∑CT of the central thicknesses of the first to fifth lenses along the optical axis and the effective focal length f of the external lens satisfy: -0.02 < ΣCT / f < 0.

[0014] More preferably, the focal length f1 of the first lens and the effective focal length f of the external lens satisfy: 1.8 < f1 / f < 4.8; the curvature radius R1 of the object side surface of the first lens and the effective focal length f of the external lens satisfy: -0.05 < R1 / f < -0.02; the curvature radius R2 of the image side surface of the first lens and the effective focal length f of the external lens satisfy: -0.05 < R2 / f < -0.02.

[0015] More preferably, the focal length f2 of the second lens and the effective focal length f of the external lens satisfy: 0.04 < f2 / f < 0.1; the equivalent curvature radius R3’ of the object side surface of the second lens and the effective focal length f of the external lens satisfy: -0.53 < R3’ / f < -0.46; the equivalent curvature radius R4’ of the image side surface of the second lens and the effective focal length f of the external lens satisfy: -0.06 < R4’ / f < -0.02.

[0016] More preferably, the focal length f3 of the third lens and the effective focal length f of the external lens satisfy: 0.24 < f3 / f < 0.43; the equivalent curvature radius R5’ of the object side surface of the third lens and the effective focal length f of the external lens satisfy: 0.04 < R5’ / f < 0.11; the equivalent curvature radius R6’ of the image side surface of the third lens and the effective focal length f of the external lens satisfy: 0.08 < R6’ / f < 0.19.

[0017] More preferably, the focal length f4 of the fourth lens and the effective focal length f of the external lens satisfy: -0.04 < f4 / f < -0.01; the equivalent curvature radius R8’ of the image side surface of the fourth lens and the effective focal length f of the external lens satisfy: 0 < R8’ / f < 0.03.

[0018] More preferably, the focal length f5 of the fifth lens and the effective focal length f of the external lens satisfy: 0.01 < f5 / f < 0.05; the equivalent curvature radius R9’ of the object side surface of the fifth lens and the effective focal length f of the external lens satisfy: 0 < R9’ / f < 0.03; the equivalent curvature radius R10’ of the image side surface of the fifth lens and the effective focal length f of the external lens satisfy: 0.09 < R10’ / f < 0.19.

[0019] Further preferably, the focal length f1 of the first lens and the combined focal length f2345 of the second lens, the third lens, the fourth lens, and the fifth lens satisfy: 1 < f1 / f2345 < 4; the clear aperture radius d1 of the object side surface of the first lens and the clear aperture radius d10 of the image side surface of the fifth lens satisfy: 2.8 < d1 / d10 < 3.

[0020] An imaging device, including a total of thirteen lenses, which sequentially include, along the optical axis from the object side to the imaging surface: the above-mentioned external lens and the own lens; the own lens is composed of eight lenses, and along the optical axis from the object side to the imaging surface are:

[0021] The sixth lens with negative optical power, its object side surface is convex, and its image side surface is concave;

[0022] The seventh lens with negative optical power, its object side surface is convex, and its image side surface is concave;

[0023] The eighth lens with negative optical power, its object side surface is concave, and its image side surface is convex;

[0024] The ninth lens with positive optical power, its object side surface is convex, and its image side surface is convex;

[0025] The tenth lens with positive optical power, its object side surface is concave, and its image side surface is convex;

[0026] The eleventh lens with positive optical power, its object side surface is convex, and its image side surface is convex;

[0027] The twelfth lens with negative optical power, its object side surface is concave, and its image side surface is concave;

[0028] The thirteenth lens with positive optical power, its object side surface is convex, and its image side surface is convex.

[0029] Compared with the prior art, the external lens and the imaging device provided by the present invention improve the imaging quality through specific surface shape matching and reasonable optical power distribution, and have one or more advantages such as miniaturization, ultra-wide angle, large target surface, large aperture, and high-quality imaging, can obtain picture information with a larger field of view angle, improve the aspect ratio of the wide-screen imaging, and greatly improve the user experience effect. Brief Description of the Drawings

[0030] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, in which:

[0031] Figure 1 It is a schematic structural diagram of the external lens in Embodiment 1 of the present invention.

[0032] Figure 2It is a perspective view of an external lens in Embodiment 1 of the present invention.

[0033] Figure 3 It is a schematic structural diagram of an external lens in Embodiment 2 of the present invention.

[0034] Figure 4 It is a schematic structural diagram of an external lens in Embodiment 3 of the present invention.

[0035] Figure 5 It is a schematic structural diagram of an external lens in Embodiment 4 of the present invention.

[0036] Figure 6 It is a schematic structural diagram of an imaging device in Embodiment 5 of the present invention.

[0037] Figure 7 It is a field curvature curve graph of the imaging device in Embodiment 5 of the present invention.

[0038] Figure 8 It is an F-Tan(Theta) distortion curve graph of the imaging device in Embodiment 5 of the present invention.

[0039] Figure 9 It is an axial aberration curve graph of the imaging device in Embodiment 5 of the present invention.

[0040] Figure 10 It is an MTF curve graph of the imaging device in Embodiment 5 of the present invention.

[0041] Figure 11 It is a relative illuminance curve graph of the imaging device in Embodiment 5 of the present invention.

[0042] Figure 12 It is a schematic structural diagram of an imaging device in Embodiment 6 of the present invention.

[0043] Figure 13 It is a field curvature curve graph of the imaging device in Embodiment 6 of the present invention.

[0044] Figure 14 It is an F-Tan(Theta) distortion curve graph of the imaging device in Embodiment 6 of the present invention.

[0045] Figure 15 It is an axial aberration curve graph of the imaging device in Embodiment 6 of the present invention.

[0046] Figure 16 It is an MTF curve graph of the imaging device in Embodiment 6 of the present invention.

[0047] Figure 17 It is a relative illuminance curve graph of the imaging device in Embodiment 6 of the present invention.

[0048] Figure 18 It is a schematic structural diagram of an imaging device in Embodiment 7 of the present invention.

[0049] Figure 19 It is the field curvature curve graph of the imaging device in Embodiment 7 of the present invention.

[0050] Figure 20 It is the F-Tan(Theta) distortion curve graph of the imaging device in Embodiment 7 of the present invention.

[0051] Figure 21 It is the axial aberration curve graph of the imaging device in Embodiment 7 of the present invention.

[0052] Figure 22 It is the MTF curve graph of the imaging device in Embodiment 7 of the present invention.

[0053] Figure 23 It is the relative illumination curve graph of the imaging device in Embodiment 7 of the present invention.

[0054] Figure 24 It is the structural schematic diagram of the imaging device in Embodiment 8 of the present invention.

[0055] Figure 25 It is the field curvature curve graph of the imaging device in Embodiment 8 of the present invention.

[0056] Figure 26 It is the F-Tan(Theta) distortion curve graph of the imaging device in Embodiment 8 of the present invention.

[0057] Figure 27 It is the axial aberration curve graph of the imaging device in Embodiment 8 of the present invention.

[0058] Figure 28 It is the MTF curve graph of the imaging device in Embodiment 8 of the present invention.

[0059] Figure 29 It is the relative illumination curve graph of the imaging device in Embodiment 8 of the present invention.

[0060] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific Embodiments

[0061] To better understand the present application, more detailed descriptions of various aspects of the present application will be made with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the embodiments of the present application and do not limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0062] It should be noted that in this specification, the expressions such as first, second, third, etc. are only used to distinguish one feature from another, and do not represent any limitation on the features. Therefore, without departing from the teachings of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0063] In the drawings, for ease of explanation, the thickness, dimensions, and shape of the lens have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are for illustrative purposes only and are not drawn to an exact scale.

[0064] In this context, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface 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 position of the concave surface 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 object being photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0065] It should also be understood that the terms "comprise", "comprising", "have", "include", and / or "including", when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features rather than an individual element in the list. In addition, when describing the embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplary" is intended to refer to an example or illustration.

[0066] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0067] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments may be combined with each other. The following will refer to the drawings and combine with the embodiments to detail the present application.

[0068] The external lens provided by the embodiment of the present invention has a total of five lenses, which sequentially include: a first lens, a second lens, a third lens, a fourth lens, and a fifth lens along the optical axis from the object side to the imaging surface. The first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all cylindrical lenses. The cylindrical lens of the present application has a focal power in the Y-axis direction (vertical field of view) and no focal power in the X-axis direction (horizontal field of view). The cylindrical lens can control the asymmetric optical path and is suitable for applications requiring one-dimensional focusing, beam shaping, or astigmatism correction.

[0069] In some embodiments, the first lens may have a negative focal power, with its object side being convex and its image side being concave. The second lens may have a negative focal power, with its object side being convex and its image side being concave. The third lens may have a negative focal power, with its object side being concave and its image side being convex. The fourth lens may have a positive focal power, with its object side being concave or convex and its image side being convex. The fifth lens may have a negative focal power, with its object side being concave and its image side being convex.

[0070] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are cylindrical lenses. Among them, the first lens may be made of glass, and the second lens, the third lens, the fourth lens, and the fifth lens may be made of plastic.

[0071] In some embodiments, the optical total length TTL of the external lens and the effective focal length f of the external lens satisfy: -0.03 < TTL / f < 0. Meeting the above range can effectively limit the length of the lens while achieving a long focal length, which is beneficial to the miniaturization of the external lens.

[0072] In some embodiments, the optical total length TTL of the external lens and the clear aperture radius d1 of the object side of the first lens satisfy: 0.88 < TTL / d1 < 0.97. It can be understood that the clear aperture radius of the object side of the first lens is the clear aperture radius in the Y direction. Meeting the above range is beneficial to the miniaturization of the external lens.

[0073] In some embodiments, the optical total length TTL of the external lens and the sum ∑CT of the central thicknesses of the first lens to the fifth lens along the optical axis respectively satisfy: 0.5 < ∑CT / TTL < 0.54. Meeting the above range can effectively compress the total length of the external lens, and is beneficial to the structural design and production process of the external lens.

[0074] In some embodiments, the sum ∑CT of the central thicknesses of the first lens to the fifth lens along the optical axis respectively and the effective focal length f of the external lens satisfy: -0.02 < ΣCT / f < 0. Meeting the above range can effectively correct the field curvature and distortion of the external lens and improve the imaging quality of the external lens.

[0075] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the external lens satisfy: 1.8 < f1 / f < 4.8; the object-side curvature radius R1 of the first lens and the effective focal length f of the external lens satisfy: -0.05 < R1 / f < -0.02; the image-side curvature radius R2 of the first lens and the effective focal length f of the external lens satisfy: -0.05 < R2 / f < -0.02. It can be understood that the object-side curvature radius of the first lens is the same as the object-side equivalent curvature radius of the first lens, and the image-side curvature radius of the first lens is the same as the image-side equivalent curvature radius of the first lens. Satisfying the above ranges, by setting the first lens to have a negative refractive power and a suitable surface shape, it is beneficial for the first lens to accommodate a larger angle of light and collect as much light as possible into the rear optical system, increasing the light flux while achieving a large field of view. More specifically, 1.91 < f1 / f < 4.469.

[0076] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the external lens satisfy: 0.04 < f2 / f < 0.1; the object-side equivalent curvature radius R3’ of the second lens and the effective focal length f of the external lens satisfy: -0.53 < R3’ / f < -0.46; the image-side equivalent curvature radius R4’ of the second lens and the effective focal length f of the external lens satisfy: -0.06 < R4’ / f < -0.02. Satisfying the above ranges can diverge a large range of light entering the system to a certain extent, which is beneficial for sharing the negative optical power of the first lens, avoiding excessive light deflection, and reducing the difficulty of aberration correction.

[0077] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the external lens satisfy: 0.24 < f3 / f < 0.43; the object-side equivalent curvature radius R5’ of the third lens and the effective focal length f of the external lens satisfy: 0.04 < R5’ / f < 0.11; the image-side equivalent curvature radius R6’ of the third lens and the effective focal length f of the external lens satisfy: 0.08 < R6’ / f < 0.19. Satisfying the above ranges is beneficial for the smooth transition of light and improving the imaging quality of the external lens.

[0078] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the external lens satisfy: -0.04 < f4 / f < -0.01; the image-side equivalent curvature radius R8’ of the fourth lens and the effective focal length f of the external lens satisfy: 0 < R8’ / f < 0.03. Satisfying the above conditions, by reasonably setting the focal length and surface shape of the fourth lens, it is beneficial for light convergence, enabling the light trend to smoothly transition to the rear, reducing the height of the light incident on the rear, slowing down the upward trend of the light, avoiding light energy loss of the large field of view light reaching the rear system, facilitating the improvement of the illuminance of the edge field of view, balancing aberrations, and being beneficial for achieving a short optical total length.

[0079] In some embodiments, the focal length f5 of the fifth lens and the effective focal length f of the external lens satisfy: 0.01 < f5 / f < 0.05; the equivalent curvature radius R9' of the object side of the fifth lens and the effective focal length f of the external lens satisfy: 0 < R9' / f < 0.03; the equivalent curvature radius R10' of the image side of the fifth lens and the effective focal length f of the external lens satisfy: 0.09 < R10' / f < 0.19. Meeting the above conditions can diverge the light rays, making the light rays in the edge field of view show an upward trend, which is beneficial for the image points on the imaging surface to be away from the optical axis, so as to facilitate the realization of a large target surface and obtain a larger picture, effectively eliminate aberrations, and improve the resolution ability of the external lens.

[0080] In some embodiments, the focal length f1 of the first lens and the combined focal length f2345 of the second, third, fourth, and fifth lenses satisfy: 1 < f1 / f2345 < 4. Meeting the above range, by reasonably setting the focal length relationship of each lens, it is beneficial for the light rays to transition smoothly, and at the same time correct various aberrations of the external lens, improving the imaging quality of the external lens. More specifically, 1.04 < f1 / f2345 < 3.84.

[0081] In some embodiments, the clear aperture radius d1 of the object side of the first lens and the clear aperture radius d10 of the image side of the fifth lens satisfy: 2.8 < d1 / d10 < 3. It can be understood that the clear aperture radii of the object side of the first lens and the image side of the fifth lens are both the clear aperture radii in the Y direction. Meeting the above range can reasonably configure the clear aperture radii of the object side of the first lens and the image side of the fifth lens, which is beneficial for restricting the size of the first lens, can provide a larger entrance pupil for the external lens to expand the aperture, so that the external lens has sufficient light transmission, and further improve the imaging quality of the external lens. More specifically, 2.88 < d1 / d10 < 2.95.

[0082] In some embodiments, the curvature radius R1 of the object side of the first lens, the curvature radius R2 of the image side of the first lens, and the central thickness CT1 of the first lens satisfy: 0.99 < R1 / (R2 + CT1) < 1.04; 1 < R1 / R2 < 1.1. Meeting the above range can make the object side and the image side close to a concentric circle structure, which is beneficial for the light rays to enter the rear lens smoothly, can reduce the field curvature, correct off-axis point aberrations, and is beneficial for the correction of the aberrations of the entire external lens, improving the imaging quality of the external lens. More specifically, 1.01 < R1 / R2 < 1.06.

[0083] In some embodiments, the radius of curvature R1 of the object side surface of the first lens and the radius of curvature R2 of the image side surface of the first lens satisfy: 0 < (R1 - R2) / (R1 + R2) < 0.04. Satisfying the above range can effectively control the surface shape of the first lens, which is beneficial to increasing the field of view angle and at the same time controlling the front aperture of the external lens, achieving a balance between a large field of view and miniaturization.

[0084] In some embodiments, the external lens satisfies the conditional formula: -1350 mm < f < -800 mm, 15 mm < TTL < 17 mm, 2.4 < Fno < 2.5, 61° < CRA < 62°, where f represents the effective focal length of the external lens, TTL represents the overall optical length of the external lens, Fno represents the aperture value of the external lens, and CRA represents the principal ray incident angle at the maximum image height of the external lens. Satisfying the above conditions indicates that the optical lens provided by the embodiments of the present invention has at least the characteristics of a large CRA, miniaturization, a large aperture, etc. More specifically, -1314.2 mm < f < -817.13 mm, 15.7 mm < TTL < 16.76 mm, 2.42 < Fno < 2.44, 61.4° < CRA < 61.9°.

[0085] The present invention also provides an imaging device, which has a total of thirteen lenses, and sequentially includes, along the optical axis from the object side to the imaging surface: the above-mentioned external lens and an in-house lens. The in-house lens is composed of eight lenses, and sequentially along the optical axis from the object side to the imaging surface are: the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, the twelfth lens, and the thirteenth lens. The external lens can be mounted in front of the object side of the lens of the imaging device. The imaging device can be an electronic device such as a smart phone, a mobile terminal, a sports camera, etc. The external lens is detachably mounted on the imaging device, which can achieve convenient installation and disassembly, and at the same time improve the aspect ratio of the wide-screen imaging, creating a visual experience comparable to that of a cinema. During the shooting process, it can also capture the unique glare effect under strong point light sources.

[0086] The external lens has a focal power in the Y direction and no focal power in the X direction, and can obtain the picture information with a larger field of view angle in the Y direction. Then, the light rays entering the lens in the Y direction are compressed. On the premise that the image height remains unchanged, the imaging information becomes more dense. After being restored by the subsequent in-house lens, the compressed picture information is expanded, and the Y direction contains more picture information. Therefore, the imaging device equipped with the external lens can obtain the picture information with a larger field of view angle in the Y direction and improve the aspect ratio of the wide-screen imaging.

[0087] Specifically, the sixth lens may have a negative focal power, with its object side being convex and its image side being concave. The seventh lens may have a negative focal power, with its object side being convex and its image side being concave. The eighth lens has a negative focal power, with its object side being concave and its image side being convex. The ninth lens may have a positive focal power, with its object side being convex and its image side being convex. The tenth lens may have a positive focal power, with its object side being concave and its image side being convex. The eleventh lens may have a positive focal power, with its object side being convex and its image side being convex. The twelfth lens may have a negative focal power, with its object side being concave and its image side being concave. The thirteenth lens may have a positive focal power, with its object side being convex and its image side being convex.

[0088] In some embodiments, the imaging device may further include a diaphragm, which may be located between the ninth lens and the tenth lens. It can be understood that the diaphragm is used to limit the amount of incident light to change the brightness of the image formation.

[0089] In some embodiments, the imaging device may further include a filter, which is disposed between the thirteenth lens and the imaging surface. The filter is used to filter out interfering light to prevent the interfering light from reaching the imaging surface of the imaging lens and affecting normal imaging.

[0090] In some embodiments, the eleventh lens and the twelfth lens may form a cemented lens group with a negative focal power, which can effectively correct the chromatic aberration of the imaging device, reduce the decentration sensitivity of the imaging device, balance the aberration of the imaging device, and improve the imaging quality of the imaging device; it can also reduce the assembly sensitivity of the imaging device, thereby reducing the processing difficulty of the imaging device and improving the assembly yield of the imaging device.

[0091] In some embodiments, the sixth lens, the eighth lens, the tenth lens, the eleventh lens, and the twelfth lens all adopt glass spherical lenses; the seventh lens, the ninth lens, and the thirteenth lens all adopt glass aspherical lenses.

[0092] In some embodiments, the imaging device satisfies the conditional expressions: 2.35mm < f’ < 2.4mm, 0.95 < EPD’ < 1, 38mm < TTL’ < 40mm, 2.4 < Fno’ < 2.45, 14° < CRA’ < 15°, where f’ represents the effective focal length of the imaging device, EPD’ represents the entrance pupil diameter of the imaging device, TTL’ represents the overall optical length of the imaging device, and Fno’ represents the f-number of the imaging device. Meeting the above conditions indicates that the imaging device provided by the embodiments of the present invention has at least: a relatively small overall optical length; a relatively large imaging surface, which can be matched with a larger-sized chip to achieve high-definition imaging; and a relatively large f-number, enabling the lens to achieve high-definition imaging even in a relatively dark environment. More specifically, 2.36mm < f’ < 2.39mm, 0.97 < EPD’ < 0.99, 38.7mm < TTL’ < 39.76mm, 2.42 < Fno’ < 2.44, 14.41° < CRA’ < 14.54°.

[0093] The present invention will be further described in multiple embodiments below. In each embodiment, the thickness, radius of curvature, and material selection of each lens are partially different. For specific differences, refer to the parameter tables of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following embodiments. Any other changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be regarded as equivalent replacement methods and are included in the protection scope of the present invention.

[0094] Embodiment 1

[0095] Please refer to Figure 1 , Figure 1 , which is a schematic structural diagram of the external lens 100 provided in Embodiment 1 of the present invention, Figure 2 and is a perspective view of the external lens 100. The external lens 100 sequentially includes, along the optical axis from the object side to the virtual plane S11: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5.

[0096] The first lens L1 has a negative optical power. Its object side surface S1 is convex, and its image side surface S2 is concave;

[0097] The second lens L2 has a negative optical power. Its object side surface S3 is convex, and its image side surface S4 is concave;

[0098] The third lens L3 has a negative optical power. Its object side surface S5 is concave, and its image side surface S6 is convex;

[0099] The fourth lens L4 has a positive optical power. Its object side surface S7 is convex, and its image side surface S8 is convex;

[0100] The fifth lens L5 has a negative optical power. Its object side S9 is concave, and its image side S10 is convex.

[0101] The first lens L1 is a glass cylindrical lens, and the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are all plastic cylindrical lenses. It can be understood that in this application, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are all cylindrical lenses. The cylindrical lenses in this application have optical power in the Y-axis direction (vertical field of view) and no optical power in the X-axis direction (horizontal field of view). The cylindrical lenses can control the asymmetric optical path and are suitable for applications requiring one-dimensional focusing, beam shaping, or astigmatism correction.

[0102] The relevant parameters of each lens in the external lens 100 in Embodiment 1 are shown in Table 1-1.

[0103] Table 1-1

[0104]

[0105] The surface shape parameters of the cylindrical lenses of the external lens 100 in Embodiment 1 are shown in Table 1-2.

[0106] Table 1-2

[0107]

[0108] The cylindrical surface shapes of each lens satisfy the following equation:

[0109] ;

[0110] where z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, y is the distance from the optical axis to the curved surface in the Y-axis direction, c is the curvature of the vertex of the curved surface, K is the conic coefficient, and A2, A4, A6, A8, A 10 、A 12 are the second-order, fourth-order, sixth-order, eighth-order, tenth-order, and twelfth-order surface coefficients respectively.

[0111] Specifically, the equivalent radius of curvature R' of each surface of the cylindrical lens is R / (1 + 2×A2×R), where A2 is the second-order surface coefficient corresponding to each surface in Table 1-2, and R is the radius of curvature corresponding to each surface in Table 1-1. It can be understood that the radius of curvature of the object side of the first lens is the equivalent radius of curvature of the object side of the first lens, and the radius of curvature of the image side of the first lens is the equivalent radius of curvature of the image side of the first lens. The convexity and concavity of the surface shape can be judged by the equivalent radius of curvature.

[0112] Embodiment 2

[0113] Please refer to Figure 3, which shows the structural schematic diagram of the external lens 200 provided in Embodiment 2 of the present invention. Compared with Embodiment 1, the main difference is that the object side surface S7 of the fourth lens L4 is a concave surface; the optical parameters such as the curvature radius of each lens surface, the lens thickness, and the distance between lenses are different.

[0114] The relevant parameters of each lens in the external lens 200 in Embodiment 2 are shown in Table 2-1.

[0115] Table 2-1

[0116]

[0117] The surface type parameters of the cylindrical lens of the external lens 200 in Embodiment 2 are shown in Table 2-2.

[0118] Table 2-2

[0119]

[0120] Embodiment 3

[0121] Please refer to Figure 4 , which shows the structural schematic diagram of the external lens 300 provided in Embodiment 3 of the present invention. Compared with Embodiment 1, the main difference is that the optical parameters such as the curvature radius of each lens surface, the lens thickness, and the distance between lenses are different.

[0122] The relevant parameters of each lens in the external lens 300 in Embodiment 3 are shown in Table 3-1.

[0123] Table 3-1

[0124]

[0125] The surface type parameters of the cylindrical lens of the external lens 300 in Embodiment 3 are shown in Table 3-2.

[0126] Table 3-2

[0127]

[0128] Embodiment 4

[0129] Please refer to Figure 5 , which shows the structural schematic diagram of the external lens 400 provided in Embodiment 4 of the present invention. Compared with Embodiment 1, the main difference is that the object side surface S7 of the fourth lens L4 is a concave surface; the optical parameters such as the curvature radius of each lens surface, the lens thickness, and the distance between lenses are different.

[0130] The relevant parameters of each lens in the external lens 400 in Embodiment 4 are shown in Table 4-1.

[0131] Table 4-1

[0132]

[0133] The surface shape parameters of the cylindrical lens of the external lens 400 in Example 4 are shown in Table 4-2.

[0134] Table 4-2

[0135]

[0136] Please refer to Table 5 for the optical characteristics of the external lenses in the above Examples 1 to 4, including the effective focal length f, the total optical length TTL, the aperture value Fno, the chief ray angle of incidence CRA at the maximum image height, and the values corresponding to each conditional formula in each example.

[0137] Table 5

[0138]

[0139] Example 5

[0140] The external lens of any of the above embodiments can be mounted in front of the object side of the lens of the imaging device, and the imaging device can be an electronic device such as a smart phone, a mobile terminal, a sports camera, etc.

[0141] Please refer to Figure 6 , which shows a schematic structural diagram of the imaging device 500 equipped with the external lens provided in Example 5 of the present invention, including the external lens 100 in Example 1 above. The imaging device 500 further includes a built-in own lens 510 and an imaging element. The own lens 510 may be a multi-lens combination. In this application, the own lens 510 is composed of eight lenses. The imaging element may be a CMOS image sensor or a CCD image sensor.

[0142] The own lens 510 includes, in order from the object side to the imaging plane S29 along the optical axis: a sixth lens L6, a seventh lens L7, an eighth lens L8, a diaphragm ST, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13, and a filter G1.

[0143] Among them, the sixth lens L6 has a negative optical power, its object side S12 is convex, and its image side S13 is concave. The seventh lens L7 has a negative optical power, its object side S14 is convex, and its image side S15 is concave. The eighth lens L8 has a negative optical power, its object side S16 is concave, and its image side S17 is convex. The ninth lens L9 has a positive optical power, its object side S18 is convex, and its image side S19 is convex. The tenth lens L10 has a positive optical power, its object side S20 is concave, and its image side S21 is convex. The eleventh lens L11 and the twelfth lens L12 form a cemented lens group with a negative optical power. The eleventh lens L11 has a positive optical power, its object side S22 is convex, and its image side S23 is convex. The twelfth lens L12 has a negative optical power, its object side S23 is concave, and its image side S24 is concave. The thirteenth lens L13 has a positive optical power, its object side S25 is convex, and its image side S26 is convex.

[0144] The sixth lens L6, the eighth lens L8, the tenth lens L10, the eleventh lens L11, and the twelfth lens L12 are all glass spherical lenses; the seventh lens L7, the ninth lens L9, and the thirteenth lens L13 are all glass aspherical lenses.

[0145] The relevant parameters of each lens in the imaging device 500 in Embodiment 5 are shown in Table 6-1.

[0146] Table 6-1

[0147]

[0148] The surface shape parameters of the aspherical lenses of the imaging device 500 in Embodiment 5 are shown in Table 6-2.

[0149] Table 6-2

[0150]

[0151] The aspherical surface shapes of each lens satisfy the following equations:

[0152] ;

[0153] where z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance from the optical axis to the curved surface, c is the curvature of the vertex of the curved surface, K is the conic coefficient, and B, C, D, E, F are the surface coefficients of the fourth, sixth, eighth, tenth, and twelfth orders respectively.

[0154] Figure 7The field curvature curve of Example 5 is shown, which represents the curvature of light rays with different wavelengths in the meridional image plane and the sagittal image plane. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field of view angle (unit: °). It can be seen from the figure that the field curvature of the meridional image plane and the sagittal image plane is controlled within -0.03 mm to 0.04 mm, indicating that the imaging device can well correct the field curvature.

[0155] Figure 8 The F-Tan(Theta) distortion curve of Example 5 is shown, which represents the F-Tan(Theta) distortion of light rays with different wavelengths at different image heights on the imaging plane. The horizontal axis represents the F-Tan(Theta) distortion value (unit: %), and the vertical axis represents the half field of view angle (unit: °). It can be seen from the figure that the F-Tan(Theta) distortion of the imaging device is controlled within -85% to 0, and the image compression in the edge angle region is relatively gentle, effectively improving the clarity of the unfolded image.

[0156] Figure 9 The axial aberration curve graph of Example 5 is shown, which represents the aberration of each wavelength on the optical axis at the imaging plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. It can be seen from the figure that the offset of the axial aberration is controlled within ±0.02 mm, indicating that the imaging device can better correct the axial aberration.

[0157] Figure 10 The MTF (Modulation Transfer Function) curve graph of Example 5 is shown, which represents the modulation of the lens imaging at different spatial frequencies under each field of view. The horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that the MTF value of this embodiment is above 0.2 within the entire field of view. In the range of 0 to 160 lp / mm, the MTF curve decreases uniformly and smoothly from the center to the edge field of view, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases.

[0158] Figure 11 The relative illumination curve of Example 5 is shown, which represents the relative illumination values at different field of view angles on the imaging plane. The horizontal axis represents the half field of view angle (unit: °), and the vertical axis represents the relative illumination (unit: %). It can be seen from the figure that the relative illumination value of the imaging device is still greater than 70% at the maximum half field of view angle, indicating that the imaging device has good relative illumination.

[0159] Example 6

[0160] Please refer to Figure 12, which shows the schematic structural diagram of the imaging device 600 equipped with an external lens provided in Embodiment 6 of the present invention. The structure of this embodiment is basically the same as that of the imaging device in Embodiment 5, and the main difference is that: the external lens mounted in this embodiment is the external lens 200 in the above-mentioned Embodiment 2.

[0161] Figure 13 The field curvature curve of Embodiment 6 is shown. It can be seen from the figure that the field curvature of the meridional image plane and the sagittal image plane is controlled within -0.03 mm to 0.04 mm, indicating that the imaging device can well correct the field curvature. Figure 14 The F-Tan(Theta) distortion curve of Embodiment 6 is shown. It can be seen from the figure that the F-Tan(Theta) distortion of the imaging device is controlled within -85% to 0, and the image compression in the edge angle region is relatively gentle, effectively improving the clarity of the unfolded image. Figure 15 The axial aberration curve graph of Embodiment 5 is shown, which represents the aberration of each wavelength on the optical axis at the imaging plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. It can be seen from the figure that the offset of the axial aberration is controlled within ±0.02 mm, indicating that the imaging device can well correct the axial aberration. Figure 16 The MTF (Modulation Transfer Function) curve graph of Embodiment 5 is shown. It can be seen from the figure that the MTF value in this embodiment is above 0.3 within the entire field of view. In the range of 0 to 160 lp / mm, the MTF curve smoothly decreases uniformly from the center to the edge of the field of view, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases. Figure 17 The relative illumination curve of Embodiment 5 is shown. It can be seen from the figure that the relative illumination value of the imaging device is still greater than 70% at the maximum semi-field angle, indicating that the imaging device has good relative illumination.

[0162] Embodiment 7

[0163] Please refer to Figure 18 , which shows the schematic structural diagram of the imaging device 700 equipped with an external lens provided in Embodiment 7 of the present invention. The structure of this embodiment is basically the same as that of the imaging device in Embodiment 5, and the main difference is that: the external lens mounted in this embodiment is the external lens 300 in the above-mentioned Embodiment 3.

[0164] Figure 19 The field curvature curve of Embodiment 7 is shown. It can be seen from the figure that the field curvature of the meridional image plane and the sagittal image plane is controlled within -0.03 mm to 0.04 mm, indicating that the imaging device can well correct the field curvature. Figure 20The F-Tan(Theta) distortion curve of Example 7 is shown. It can be seen from the figure that the F-Tan(Theta) distortion of the imaging device is controlled within -85% to 0, and the image compression in the edge angle region is relatively gentle, effectively improving the clarity of the unfolded image. Figure 21 The axial aberration curve graph of Example 7 is shown, which represents the aberration of each wavelength on the optical axis at the imaging plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. It can be seen from the figure that the offset of the axial aberration is controlled within ±0.02 mm, indicating that the imaging device can correct the axial aberration well. Figure 22 The MTF (Modulation Transfer Function) curve graph of Example 7 is shown. It can be seen from the figure that the MTF value of this embodiment is above 0.3 within the entire field of view. In the range of 0 to 160 lp / mm, the MTF curve decreases uniformly and smoothly from the center to the edge of the field of view, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases. Figure 23 The relative illumination curve of Example 7 is shown. It can be seen from the figure that the relative illumination value of the imaging device is still greater than 70% at the maximum half field angle, indicating that the imaging device has good relative illumination.

[0165] Example 8

[0166] Please refer to Figure 24 , which shows the structural schematic diagram of the imaging device 800 equipped with an external lens provided in Embodiment 8 of the present invention. The structure of the imaging device in this embodiment is basically the same as that in Embodiment 5, and the main difference is that: the external lens mounted in this embodiment is the external lens 400 in the above-mentioned Embodiment 4.

[0167] Figure 25 The field curvature curve of Example 8 is shown. It can be seen from the figure that the field curvatures of the meridional image plane and the sagittal image plane are controlled within -0.03 mm to 0.04 mm, indicating that the imaging device can correct the field curvature well. Figure 26 The F-Tan(Theta) distortion curve of Example 8 is shown. It can be seen from the figure that the F-Tan(Theta) distortion of the imaging device is controlled within -85% to 0, and the image compression in the edge angle region is relatively gentle, effectively improving the clarity of the unfolded image. Figure 27 The axial aberration curve graph of Example 8 is shown, which represents the aberration of each wavelength on the optical axis at the imaging plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. It can be seen from the figure that the offset of the axial aberration is controlled within ±0.02 mm, indicating that the imaging device can correct the axial aberration well. Figure 28The MTF (Modulation Transfer Function) curve graph of Embodiment 8 is shown. It can be seen from the graph that the MTF value of this embodiment is above 0.3 within the entire field of view. In the range of 0 - 160 lp / mm, the MTF curve smoothly decreases uniformly from the center to the edge of the field of view, and it has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases. Figure 29 The relative illumination curve of Embodiment 8 is shown. It can be seen from the graph that when the maximum semi-field angle is reached, the relative illumination value of the imaging device is still greater than 70%, indicating that the imaging device has good relative illumination.

[0168] Please refer to Table 7, which provides the optical parameters of the proprietary lens 510 from Embodiment 5 to Embodiment 8 and the imaging device after mounting the external lens, including the effective focal length f’ of the imaging device, the aperture value Fno’, the maximum field of view angle FOVy in the Y direction, the maximum field of view angle FOVx in the X direction, the semi-image height ihy corresponding to the maximum field of view angle in the Y direction, and the semi-image height ihx corresponding to the maximum field of view angle in the X direction.

[0169] Table 7

[0170]

[0171] It can be seen from Table 7 that the imaging device with the external lens mounted can obtain the picture information with a larger field of view angle in the Y direction, improving the aspect ratio of widescreen imaging.

[0172] Based on the above embodiments, the external lens and the imaging device provided by the present invention have the following advantages:

[0173] The external lens and the imaging device provided by the present invention, through specific surface shape matching and reasonable optical power distribution, improve the imaging quality, and have one or more advantages such as miniaturization, ultra-wide angle, large target surface, large aperture, and high-quality imaging. They can obtain the picture information with a larger field of view angle, improve the aspect ratio of widescreen imaging, and greatly improve the user experience.

[0174] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0175] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended claims.

Claims

1. An external lens, consisting of five lenses in total, characterized in that, From the object side to the imaging surface along the optical axis, it sequentially includes: A first lens with a negative optical power, whose object side is convex and whose image side is concave; A second lens with a negative optical power, whose object side is convex and whose image side is concave; A third lens with a negative optical power, whose object side is concave and whose image side is convex; A fourth lens with a positive optical power, whose image side is convex; A fifth lens with a negative optical power, whose object side is concave and whose image side is convex; The first lens, the second lens, the third lens, the fourth lens, and the fifth lens are cylindrical lenses; Wherein, the total optical length TTL of the external lens and the effective focal length f of the external lens satisfy: -0.03 < TTL / f < 0.

2. The external lens according to claim 1, wherein The total optical length TTL of the external lens and the clear aperture radius d1 of the object side of the first lens satisfy: 0.88 < TTL / d1 < 0.

97.

3. The external lens according to claim 1, wherein The total optical length TTL of the external lens and the sum ∑CT of the central thicknesses of the first lens to the fifth lens along the optical axis respectively satisfy: 0.5 < ∑CT / TTL < 0.54; the sum ∑CT of the central thicknesses of the first lens to the fifth lens along the optical axis respectively and the effective focal length f of the external lens satisfy: -0.02 < ΣCT / f < 0.

4. The external lens according to claim 1, characterized in that, The focal length f1 of the first lens and the effective focal length f of the external lens satisfy: 1.8 < f1 / f < 4.8; the curvature radius R1 of the object side of the first lens and the effective focal length f of the external lens satisfy: -0.05 < R1 / f < -0.02; the curvature radius R2 of the image side of the first lens and the effective focal length f of the external lens satisfy: -0.05 < R2 / f < -0.

02.

5. The external lens according to claim 1, wherein The focal length f2 of the second lens and the effective focal length f of the external lens satisfy: 0.04 < f2 / f < 0.1; the equivalent curvature radius R3’ of the object side of the second lens and the effective focal length f of the external lens satisfy: -0.53 < R3’ / f < -0.46; the equivalent curvature radius R4’ of the image side of the second lens and the effective focal length f of the external lens satisfy: -0.06 < R4’ / f < -0.

02.

6. The external lens according to claim 1, wherein The focal length f3 of the third lens and the effective focal length f of the external lens satisfy: 0.24 < f3 / f < 0.43; the equivalent curvature radius R5’ of the object side of the third lens and the effective focal length f of the external lens satisfy: 0.04 < R5’ / f < 0.11; the equivalent curvature radius R6’ of the image side of the third lens and the effective focal length f of the external lens satisfy: 0.08 < R6’ / f < 0.

19.

7. The external lens according to claim 1, wherein The focal length f4 of the fourth lens and the effective focal length f of the external lens satisfy: -0.04 < f4 / f < -0.01; the equivalent curvature radius R8’ of the image side of the fourth lens and the effective focal length f of the external lens satisfy: 0 < R8’ / f < 0.

03.

8. The external lens according to claim 1, characterized in that, The focal length f5 of the fifth lens and the effective focal length f of the external lens satisfy: 0.01 < f5 / f < 0.05; the equivalent curvature radius R9' of the object side of the fifth lens and the effective focal length f of the external lens satisfy: 0 < R9' / f < 0.03; the equivalent curvature radius R10' of the image side of the fifth lens and the effective focal length f of the external lens satisfy: 0.09 < R10' / f < 0.

19.

9. The external lens according to claim 1, characterized in that, The focal length f1 of the first lens and the combined focal length f2345 of the second lens, the third lens, the fourth lens, and the fifth lens satisfy: 1 < f1 / f2345 < 4; the clear aperture radius d1 of the object side of the first lens and the clear aperture radius d10 of the image side of the fifth lens satisfy: 2.8 < d1 / d10 < 3.

10. An imaging device, characterized in that, Along the optical axis from the object side to the imaging surface, it sequentially includes: the external lens according to any one of claims 1-9 and the self-owned lens; the self-owned lens is composed of eight lenses, and along the optical axis from the object side to the imaging surface, they are: The sixth lens with a negative optical power, its object side is convex, and its image side is concave; The seventh lens with a negative optical power, its object side is convex, and its image side is concave; The eighth lens with a negative optical power, its object side is concave, and its image side is convex; The ninth lens with a positive optical power, its object side is convex, and its image side is convex; The tenth lens with a positive optical power, its object side is concave, and its image side is convex; The eleventh lens with a positive optical power, its object side is convex, and its image side is convex; The twelfth lens with a negative optical power, its object side is concave, and its image side is concave; The thirteenth lens with a positive optical power, its object side is convex, and its image side is convex.

Images