An optical imaging system

Abstract

The invention discloses an optical imaging system. The optical imaging system is a seven-piece aspherical structure, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an infrared filter and an image sensor, which are arranged in sequence from the object side to the image side. The first lens has a positive refractive power, the second lens has a negative refractive power, the third lens has a positive refractive power, the fourth lens has a refractive power, and the fifth lens has a refractive power. The object side surface of the fifth lens is a reverse curved shape, and the central part is convex toward the object surface direction. The edge part of the fifth lens is all curved toward the object surface direction, and its shape is an Arabic numeral "3". The sixth lens has a refractive power, and the seventh lens has a refractive power. The optical imaging system can well solve the stray light problem, greatly reduce the tolerance sensitivity of the camera module to the surface error, eccentricity, concentricity and tilt error, and improve the yield rate of the camera module.

Description

Technical Field

[0001] The present invention relates to an optical imaging system, and in particular to a miniaturized optical imaging system applied to electronic products. Background Art

[0002] The newly launched smartphones have been continuously upgraded in their rear camera. In just a few years, the mobile phone camera has experienced an upgrade from 6M→8M→13M→16M→24M→48M→64M→108M, and the rear pixel is almost upgraded once a year. According to the supply chain channels of the camera industry, some well-known mobile phone manufacturers have planned to include 216M pixels in the development agenda in the next two years. Mobile phone manufacturers win the market by continuously upgrading the camera pixels and increasing the camera functions.

[0003] In order to continuously upgrade the pixel of mobile phone cameras, a major change in mobile phone camera technology is the use of larger CMOS used in digital cameras to improve image quality. 1 / 1.7-inch CMOS has now become a new choice for mobile phone camera sensors. More mobile phones are also using 1 / 2.3-inch sensors. The sensors used by these traditional card DC cameras have become the choice of the new generation of camera phones. Obviously, mobile phones have begun to eliminate traditional digital cameras in terms of hardware parameters.

[0004] Due to the increasing requirements for the number of pixels and resolution, the top specifications of all smartphone cameras with more than 20 million pixels are generally six-piece aspherical lenses. Six-piece aspherical lenses have been used for many years, but they can generally only be used for mobile phone cameras below 24M. For mobile phone cameras with higher pixels, it is difficult to meet the requirements due to the increase in sensor panel size and field of view. This requires the use of seven-piece aspherical lenses or more plastic aspherical lenses. With the expansion of the application of mobile phone cameras with multiple lenses and seven-piece aspherical lenses, smartphones will trigger new demands for cameras in the future.

[0005] Currently, all well-known mobile phone manufacturers have three-lens or multi-lens solutions, and are also discussing the introduction of seven-piece aspherical lenses for mobile phone cameras. Each single lens in the three-lens camera has a very high specification, and in the future, we may also see one or two seven-piece aspherical lenses in the three-lens camera.

[0006] As for the mobile phone camera with seven aspherical lenses, its specifications are higher and can achieve better imaging quality, but at the same time it poses huge challenges to the optical design, ultra-precision processing of lenses, assembly accuracy, and the final assembly yield. First of all, for the mobile phone camera with seven aspherical lenses, since each lens is a plastic aspherical surface, the requirements for the surface error, concentricity, tilt, and assembly error of the lens are very strict. First of all, the surface error and Yas of the lens are generally required to be within 1 Newton ring (that is, the surface error is about 0.3 microns), and the assembly error between the lens itself and the lenses is generally required to be within 2 microns. The concentricity of the two surfaces of the lens and the concentricity between the lenses are also required to be within 1 micron, so as to ensure clear imaging on the sensor. At the same time, due to the use of seven plastic aspherical surfaces, the overall transmittance of mobile phone cameras is also reduced a lot, generally not exceeding 70%; in addition, since the number of mobile phone cameras is more, the Fresnel partial reflections between each surface are also more, and the stray light or ghosting problems will be more serious than the previous six- and five-element cameras. This requires that each lens of the camera must be coated with an anti-reflection film to improve the transmittance and stray light problems.

[0007] In recent years, there have been designs for seven-piece mobile phone cameras, such as the Taiwan patent TW201403166A, which solves the problem of large field of view (field of view angle greater than 80 degrees) and large panel sensors, and can obtain clear imaging. However, these structures also have some problems. The second surface 162 of the sixth lens 160 is too convex in the center, and the center thickness of the lens exceeds twice the thickness of the edge of the lens, which will cause the surface 162 to be very sensitive to surface error, eccentricity, concentricity, and tilt error. In addition, the uneven thickness of the lens can easily cause the lens to produce an uneven surface error in the XY direction during the injection molding and demolding process, resulting in blurring and ghosting when the camera takes pictures, reducing the yield rate of the camera. Another major problem is that the partial reflection of the convex part in the middle of the second surface 162 of the sixth lens 160 will cause stray light and ghosting. When facing strong light, the position within the 0.707 field of view of the image plane is prone to produce stray light that cannot be eliminated. The solution is to coat the surface of the lens with a high transmittance anti-reflection film to improve the stray light problem to a certain extent. Summary of the invention

[0008] The purpose of the present invention is to overcome the above-mentioned defects in the prior art and to provide an optical imaging system that can effectively solve the stray light problem, greatly reduce the tolerance sensitivity of the camera module to surface error, eccentricity, concentricity and tilt error, and improve the yield rate of the camera module.

[0009] To achieve the above-mentioned purpose, the present invention provides an optical imaging system, which is a seven-piece aspherical structure, including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an infrared filter and an image sensor, which are arranged in sequence from the object side to the image side, the first lens has a positive refractive power, the second lens has a negative refractive power, the third lens has a positive refractive power, the fourth lens has a refractive power, the fifth lens has a refractive power, the fifth lens has a refractive power, the fifth lens has an object side surface of the fifth lens and an image side surface of the fifth lens, the object side surface of the fifth lens is a reverse curved shape, and the central part is convex toward the object plane. The area between the center and the edge is curved toward the image plane, the edge of the fifth lens is all curved toward the object plane, and its shape is an Arabic numeral "3", the sixth lens has a refractive power, the sixth lens has a sixth lens object side surface and a sixth lens image side surface, the center of the object side surface of the sixth lens is convex toward the object plane, and the center of the image side surface of the sixth lens is convex toward the image plane, the seventh lens has a refractive power, the seventh lens has a seventh lens object side surface and a seventh lens image side surface, the center of the object side surface of the seventh lens is concave toward the inside of the lens, and the center of the image side surface of the seventh lens is concave toward the inside of the lens.

[0010] Preferably, the ratio of the edge thickness to the center thickness of the fourth lens, the fifth lens and the sixth lens is: 0.2<DT / DC<4.

[0011] Preferably, the combined focal length of the optical imaging system is in the range of 3.65 mm < f < 7.5 mm, and the diagonal size of the image plane is greater than 6.4 mm.

[0012] Preferably, the first lens has a first lens object side surface and a first lens image side surface, the first lens object side surface and the first lens image side surface are both curved toward the image plane, and the ratio of the focal length f1 of the first lens to the combined focal length f of the optical imaging system is The first lens is a low-refractive-index, high-abbe number optical material component, wherein the refractive index nd is less than 1.58 and the abe number vd is greater than 50.

[0013] Preferably, the center thickness of the second lens is thinner than the edge thickness, and the ratio of the focal length f2 of the second lens to the combined focal length f of the optical imaging system is The second lens is a component made of an optical material with a high refractive index and a low dispersion coefficient, wherein the refractive index nd is greater than 1.6 and the dispersion coefficient vd is less than 30.

[0014] Preferably, the ratio of the focal length f3 of the third lens to the combined focal length f of the optical imaging system is The third lens is a component made of an optical material with a low refractive index and a high dispersion coefficient, wherein the refractive index nd is less than 1.58 and the dispersion coefficient vd is greater than 50.

[0015] Preferably, the fourth lens has a fourth lens object side surface and a fourth lens image side surface, the fourth lens object side surface is curved toward the object plane, and the ratio of the focal length f4 of the fourth lens to the combined focal length f of the optical imaging system is The fourth lens is a component made of an optical material with a high refractive index and a low dispersion coefficient, wherein the refractive index nd is greater than 1.6 and the dispersion coefficient vd is less than 30.

[0016] Preferably, the fifth lens has a fifth lens object side surface and a fifth lens image side surface, the curved surface of the fifth lens object side surface is designed to be relatively gentle, and the ratio of its sagittal height to the optical clear aperture is less than 0.2, that is, Its radius of curvature R 251 The ratio of the combined focal length f of the optical imaging system is The ratio of the focal length f5 of the fifth lens to the combined focal length f of the optical imaging system is

[0017] Preferably, the ratio of the focal length f6 of the sixth lens to the combined focal length f of the optical imaging system is

[0018] Preferably, the seventh lens is thinner in the middle, gradually thickens from the middle to the edge, and then thins again, the ratio of the thickest part to the thinnest part of the seventh lens is less than 3, the object side surface and the image side surface of the seventh lens are both relatively flat, and the ratio of the sagitta to the aperture is less than 0.2, that is, and

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention is provided with an optical imaging system, which is a seven-piece aspherical structure, including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an infrared filter and an image sensor, which are arranged in sequence from the object side to the image side, wherein the first lens has a positive refractive power, the second lens has a negative refractive power, the third lens has a positive refractive power, the fourth lens has a refractive power, the fifth lens has a refractive power, the fifth lens has a refractive power, the fifth lens has an object side surface of the fifth lens and an image side surface of the fifth lens, the object side surface of the fifth lens is in a reverse curve shape, the central portion is convex toward the object plane, the area between the central portion and the edge portion is curved toward the image plane, the edge portion of the fifth lens is all curved toward the object plane, and the shape is an Arabic numeral "3", the sixth lens has a refractive power, the sixth lens has an object side surface of the sixth lens and an image side surface of the sixth lens, the central portion of the object side surface of the sixth lens The center of the image side surface of the sixth lens is convex toward the object plane, and the center of the image side surface of the sixth lens is convex toward the image plane. The seventh lens has a refractive power. The seventh lens has a seventh lens object side surface and a seventh lens image side surface. The center of the object side surface of the seventh lens is concave toward the inside of the lens. The center of the image side surface of the seventh lens is concave toward the inside of the lens. The optical imaging system designs the fifth lens into a reverse curved shape, which can share a part of the refractive power of the sixth lens, so that the sixth lens can be thinned. The optical imaging system can control the edge thickness and center thickness ratio of the fourth lens, the fifth lens and the sixth lens to within 0.5<DT / DC<2, and at the same time electrically controls the thickness ratio of the seventh lens, and can improve the image plane curvature problem caused by the large sensor size. The optical imaging system can well solve the stray light problem, greatly reduce the tolerance sensitivity of the camera module to the surface error, eccentricity, concentricity and tilt error, and improve the yield rate of the camera module. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a cross-sectional view of a seven-element optical imaging system proposed in patent TW201403166A;

[0023] Figure 2 is a cross-sectional view of an optical imaging system according to Embodiment 1 of the present invention;

[0024] Figure 3is a cross-sectional view of a first lens of an optical imaging system according to Embodiment 1 of the present invention;

[0025] Figure 4 is a cross-sectional view of a second lens of an optical imaging system according to Embodiment 1 of the present invention;

[0026] Figure 5 is a cross-sectional view of a third lens of an optical imaging system according to Embodiment 1 of the present invention;

[0027] Figure 6 is a cross-sectional view of a fourth lens of an optical imaging system according to Embodiment 1 of the present invention;

[0028] Figure 7 is a cross-sectional view of a fifth lens element of an optical imaging system according to Embodiment 1 of the present invention;

[0029] Figure 8 is a cross-sectional view of a sixth lens of an optical imaging system according to Embodiment 1 of the present invention;

[0030] Fig. 9 is a cross-sectional view of a seventh lens element of an optical imaging system according to Embodiment 1 of the present invention;

[0031] Fig.10 is a light path diagram of an optical imaging system according to Embodiment 1 of the present invention;

[0032] Fig.11 is a modulation transfer function MTF curve of an optical imaging system according to embodiment 1 of the present invention;

[0033] Fig.12 is an MTF-focal depth curve of an optical imaging system according to Embodiment 1 of the present invention;

[0034] Fig.13 is a point diagram of an optical imaging system according to Embodiment 1 of the present invention;

[0035] Fig.14 The first embodiment of the present invention is a field curvature and F-Tan (θ) distortion of an optical imaging system;

[0036] Fig.15 is a cross-sectional view of an optical imaging system according to a second embodiment of the present invention;

[0037] Fig.16 is a cross-sectional view of a first lens of an optical imaging system according to a second embodiment of the present invention;

[0038] Fig.17 is a cross-sectional view of a second lens of an optical imaging system according to a second embodiment of the present invention;

[0039] Fig.18 is a cross-sectional view of a third lens of an optical imaging system according to a second embodiment of the present invention;

[0040] Fig.19 is a cross-sectional view of a fourth lens of an optical imaging system according to a second embodiment of the present invention;

[0041] Fig. 20 is a cross-sectional view of a fifth lens of an optical imaging system according to a second embodiment of the present invention;

[0042] Fig.21 is a cross-sectional view of a sixth lens of an optical imaging system according to a second embodiment of the present invention;

[0043] Fig. 22 is a cross-sectional view of a seventh lens of an optical imaging system according to a second embodiment of the present invention;

[0044] Fig.23 is a light path diagram of an optical imaging system according to a second embodiment of the present invention;

[0045] Fig.24 is a point diagram of an optical imaging system according to a second embodiment of the present invention;

[0046] Fig.25 The field curvature and F-Tan(θ) distortion of an optical imaging system according to the second embodiment of the present invention;

[0047] Fig.26 is a cross-sectional view of an optical imaging system according to a third embodiment of the present invention;

[0048] Fig. 27 is a cross-sectional view of a first lens of an optical imaging system according to a third embodiment of the present invention;

[0049] Fig.28 is a cross-sectional view of a second lens and a third lens of an optical imaging system according to a third embodiment of the present invention;

[0050] Fig.29 is a cross-sectional view of a fourth lens of an optical imaging system according to a third embodiment of the present invention;

[0051] Fig.30 is a cross-sectional view of a fifth lens element of an optical imaging system according to a third embodiment of the present invention;

[0052] Fig.31 is a cross-sectional view of a sixth lens element of an optical imaging system according to a third embodiment of the present invention;

[0053] Fig.32 is a cross-sectional view of a seventh lens element of an optical imaging system according to a third embodiment of the present invention;

[0054] Fig.33 is a light path diagram of an optical imaging system according to a third embodiment of the present invention;

[0055] Fig.34is a point diagram of an optical imaging system according to a third embodiment of the present invention;

[0056] Fig.35 This is the field curvature and F-Tan (θ) distortion of an optical imaging system according to the third embodiment of the present invention.

[0057] Included in the figure are:

[0058] 2-optical imaging system, 21-first lens, 22-second lens, 23-third lens, 24-fourth lens, 25-fifth lens, 26-sixth lens, 27-seventh lens, 28-infrared filter, 29-image sensor, 211-object side surface of the first lens, 212-image side surface of the first lens, 221-object side surface of the second lens, 222-image side surface of the second lens, 231-object side surface of the third lens, 232-image side surface of the third lens, 241-object side surface of the fourth lens, 242-image side surface of the fourth lens, 251-object side surface of the fifth lens, 252-image side surface of the fifth lens, 261-object side surface of the sixth lens, 262-image side surface of the sixth lens, 271-object side surface of the seventh lens, 272-image side surface of the seventh lens, 281-object side surface of the infrared filter, 282-image side surface of the infrared filter, 291-image plane. DETAILED DESCRIPTION

[0059] The technical scheme in this embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in this embodiment of the present invention. Obviously, the described embodiment is one embodiment of the present invention, not all embodiments of the present invention. Based on this embodiment of the present invention, all other embodiments of the present invention obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] Embodiment 1

[0061] Please refer to Figures 2 to 9 The first embodiment provides an optical imaging system, wherein the optical imaging system 2 is a seven-piece aspherical structure, including a first lens 21, a second lens 22, a third lens 23, a fourth lens 24, a fifth lens 25, a sixth lens 26, a seventh lens 27, an infrared filter 28 and an image sensor 29, which are arranged in sequence from the object side to the image side, and the aperture stop is located on the object side surface 211 of the first lens.

[0062] The combined focal length of the optical imaging system 2 is in the range of 3.65mm<f<7.5mm, and the diagonal size of the image plane is greater than 6.4mm. In the first embodiment, the combined focal length of the optical imaging system 2 is preferably f=3.827817451978569mm.

[0063] The cross-sectional view of the first lens 21 is as follows Figure 3 As shown, it has positive refractive power, the first lens 21 has a first lens object side surface 211 and a first lens image side surface 212, the first lens object side surface 211 and the first lens image side surface 212 are curved toward the image plane, and the ratio of the focal length f1 of the first lens 21 to the combined focal length f of the optical imaging system 2 is The first lens 21 is a low-refractive-index, high-abbe number optical material component, wherein the refractive index nd is less than 1.58, and the abe number vd is greater than 50.

[0064] The cross-sectional view of the second lens 22 is as follows Figure 4 As shown, it has a negative refractive power, the center thickness of the second lens 22 is thinner than the edge thickness, the second lens 22 has a second lens object side surface 221 and a second lens image side surface 222, the second lens object side surface 221 is slightly recurved, the center portion of the second lens object side surface 221 is curved toward the image plane, and the edge portion is slightly curved toward the object side; the second lens image side surface 222 is curved toward the image plane, and the ratio of the focal length f2 of the second lens 22 to the combined focal length f of the optical imaging system 2 is The second lens 22 is a component made of an optical material with a high refractive index and a low dispersion coefficient, wherein the refractive index nd is greater than 1.6 and the dispersion coefficient vd is less than 30.

[0065] The cross-sectional view of the third lens 23 is as follows: Figure 5 As shown, it has positive refractive power, the third lens 23 has a third lens object side surface 231 and a third lens image side surface 232, the third lens object side surface 231 is curved toward the image plane, and the third lens image side surface 232 is curved toward the object plane. The ratio of the focal length f3 of the third lens 23 to the combined focal length f of the optical imaging system 2 is The third lens 23 is a low-refractive-index, high-abbe number optical material component, wherein the refractive index nd is less than 1.58, and the abe number vd is greater than 50.

[0066] The cross-sectional view of the fourth lens 24 is as follows Figure 6 As shown, it has a refractive power, the fourth lens 24 has a fourth lens object side surface 241 and a fourth lens image side surface 242, the fourth lens object side surface 241 and the fourth lens image side surface 242 are curved toward the object plane, and the ratio of the focal length f4 of the fourth lens 24 to the combined focal length f of the optical imaging system 2 is The fourth lens 24 is a component made of an optical material with a high refractive index and a low dispersion coefficient, wherein the refractive index nd is greater than 1.6 and the dispersion coefficient vd is less than 30.

[0067] The cross-sectional view of the fifth lens 25 is as follows: Figure 7As shown, it has a diopter, the fifth lens 25 has a fifth lens object side surface 251 and a fifth lens image side surface 252, the fifth lens object side surface 251 is in an inverse shape, the central portion is convex toward the object plane, and the area between the central portion and the edge portion is curved toward the image plane, the fifth lens object side surface 251 and the edge portion of the fifth lens image side surface 252 are all curved toward the object plane, and the shape thereof is an Arabic numeral "3". By designing the inverse shape of the fifth lens 25, it can share a part of the diopter of the sixth lens 26, so that the thickness of the sixth lens 26 can be designed to be thinner, the curved surface design of the fifth lens object side surface 251 is relatively gentle, and the ratio of its sagittal height to the optical clear aperture is less than 0.2, that is, The fifth lens object side surface 251 has a curvature radius R 251 The ratio of the combined focal length f of the optical imaging system 2 is The ratio of the focal length f5 of the fifth lens 25 to the combined focal length f of the optical imaging system 2 is

[0068] The cross-sectional view of the sixth lens 26 is as follows Figure 8 As shown, it has a refractive power, the sixth lens 26 has a sixth lens object side surface 261 and a sixth lens image side surface 262, the sixth lens object side surface 261 has a slightly reversed shape, the center portion of which is curved toward the image plane and convex toward the object plane, while the edge portion is curved toward the object plane, the sixth lens image side surface 262 is curved toward the object plane and convex toward the image plane, and the ratio of the focal length f6 of the sixth lens 26 to the combined focal length f of the optical imaging system 2 is

[0069] The cross-sectional view of the seventh lens 27 is as follows Fig. 9 As shown, it has a refractive power, the seventh lens 27 is thinner in the middle, gradually thickens from the middle to the edge, and then thins again, the ratio of the thickest to the thinnest part of the seventh lens 27 is less than 3, the seventh lens 27 has a seventh lens object side surface 271 and a seventh lens image side surface 272, the central part of the seventh lens object side surface 271 is curved toward the object plane, concave toward the inside of the lens, and the edge part is curved toward the image plane, the central part of the seventh lens image side surface 272 is curved toward the image plane, concave toward the inside of the lens, and the edge part is curved toward the object plane, the seventh lens object side surface 271 and the seventh lens image side surface 272 are both relatively flat, and the ratio of the sagittal height to the aperture is less than 0.2, that is, and

[0070] The optical imaging system 2 of the seven-piece aspherical structure proposed in the first embodiment designs the fifth lens 25 into a reverse curved shape, which can share a part of the refractive power of the sixth lens 26, so that the sixth lens 26 can be thinned. The optical imaging system 2 can control the ratio of the edge thickness to the center thickness of the fourth lens 24, the fifth lens 25 and the sixth lens 26 to within 0.2<DT / DC<4, and also controls the thickness ratio of the seventh lens 27, and can improve the image curvature problem caused by the large sensor size. The optical imaging system 2 can well solve the stray light problem, greatly reduce the tolerance sensitivity of the camera module to the surface error, eccentricity, concentricity and tilt error, and improve the yield rate of the camera module.

[0071] The optical path parameters of the lenses in the optical imaging system 2 of the first embodiment, including the radius of curvature, thickness, refractive index nd, Abbe coefficient Vd, clear aperture, cone coefficient and focal length of each lens are shown in Table 1.

[0072] The first lens 21 has positive refractive power. The first lens 21 is an optical material component with low refractive index and high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In this embodiment 1, its refractive index nd is preferably 1.544502, the Abbe coefficient vd is 55.986991, and the focal length is 5.6502358 mm.

[0073] The second lens 22 has negative refractive power. The second lens 22 is an optical material component with high refractive index and low dispersion coefficient. Its refractive index nd>1.60 and its dispersion coefficient vd<30. In this embodiment 1, its refractive index nd=1.661319, Abbe coefficient vd=20.374576, and focal length are preferably -12.584821 mm.

[0074] The third lens 23 has positive refractive power. The third lens 23 is an optical material component with low refractive index and high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In this embodiment 1, its refractive index nd is preferably 1.544502, the Abbe coefficient vd is 55.986991, and the focal length is 6.4870885 mm.

[0075] The fourth lens 24 has a refractive power. The fourth lens 24 is an optical material component with a high refractive index and a low dispersion coefficient. Its refractive index nd>1.60 and its dispersion coefficient vd<30. In the first embodiment, its refractive index nd=1.661319, Abbe coefficient vd=20.374576, and focal length are preferably -5.3258553 mm.

[0076] The fifth lens 25 has a refractive power. The fifth lens 25 is an optical material component with a low refractive index and a high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In this embodiment 1, its refractive index nd is preferably 1.544502, its Abbe coefficient vd is preferably 55.986991, and its focal length is 3.7967055 mm.

[0077] The sixth lens 26 has a refractive power. The sixth lens 26 is an optical material component with a high refractive index and a low dispersion coefficient. Its refractive index nd>1.60 and its dispersion coefficient vd<30. In the first embodiment, its refractive index nd=1.661319, Abbe coefficient vd=20.374576, and focal length are preferably 5.3048433 mm.

[0078] The seventh lens 27 has a refractive power. The seventh lens 27 is an optical material component with a low refractive index and a high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In this embodiment 1, its refractive index nd is preferably 1.544919, the Abbe coefficient vd is 55.929938, and the focal length is -2.4182302 mm.

[0079] Table 1 Optical path parameters of lenses in the optical imaging system 2 of this embodiment 1:

[0080]

[0081]

[0082] The aspheric coefficients of each mirror surface in the optical imaging system 2 of the first embodiment, from the quadratic coefficient a1 to the sixteenth coefficient a8, are shown in Table 2. The aspheric surface is expressed as follows:

[0083]

[0084] Wherein z is the vector height (SAG); c is the curvature, which is the inverse of the radius of curvature; r is the radius of the aspheric aperture; a1, a2, a3... are the various aspheric coefficients.

[0085] Table 2 shows the aspheric coefficient of each mirror surface in the optical imaging system 2 of the first embodiment:

[0086]

[0087]

[0088] The optical path diagram of the optical imaging system 2 of this embodiment is as follows: Fig.10 As shown, its MTF curve is as follows Fig.11As shown in the figure, at the position of 110 line pairs, the modulation transfer function of the central field of view exceeds 0.82, the worst modulation transfer function of the edge 1 field of view also exceeds 0.55, and the modulation transfer functions of other fields of view are all above 0.6. Its MTF-focal depth curve is as follows Fig.12 As shown in the figure, the MTF at the focal position is relatively concentrated, and there is almost no focus shift caused by field curvature. The point diagram is as follows Fig.13 As shown, the minimum root mean square point diagram size of the central field of view is about 1 micron, and the field curvature and distortion curves are as follows Fig.14 As shown, its F-Tan(θ) is controlled within 1.5%, and the design result reaches the expected goal. At the same time, since the fourth lens 24, the fifth lens 25 and the sixth lens 26 are designed to be relatively flat, the image side surface 262 of the sixth lens does not have a particularly protruding part, which greatly improves the tolerance sensitivity of the lens, solves the problem of stray light, and improves the yield rate of the camera.

[0089] Embodiment 2

[0090] Please refer to Figures 15 to 22 The second embodiment provides an optical imaging system, wherein the optical imaging system 2 is a seven-piece aspherical structure, including a first lens 21, a second lens 22, a third lens 23, a fourth lens 24, a fifth lens 25, a sixth lens 26, a seventh lens 27, an infrared filter 28 and an image sensor 29, which are arranged in sequence from the object side to the image side, and the aperture stop is located on the image side surface 212 of the first lens.

[0091] The second embodiment provides an optical imaging system 2, the cross-sectional view of which is shown in FIG. Fig.15 As shown, the combined focal length of the optical imaging system 2 is in the range of 3.65mm<f<7.5mm, and the image plane diagonal size is greater than 6.4mm. In the second embodiment, the combined focal length of the optical imaging system 2 is preferably f=4.2878353mm.

[0092] The cross-sectional view of the first lens 21 is as follows Fig.16 As shown, it has positive refractive power, the first lens 21 has a first lens object side surface 211 and a first lens image side surface 212, the first lens object side surface 211 and the first lens image side surface 212 are curved toward the image plane, and the ratio of the focal length f1 of the first lens 21 to the combined focal length f of the optical imaging system 2 is The first lens 21 is a low-refractive-index, high-abbe number optical material component, wherein the refractive index nd is less than 1.58, and the abe number vd is greater than 50.

[0093] The cross-sectional view of the second lens 22 is as follows Fig.17As shown, it has a negative refractive power, the center thickness of the second lens 22 is thinner than the edge thickness, the second lens 22 has a second lens object side surface 221 and a second lens image side surface 222, the second lens object side surface 221 is curved toward the image plane, the second lens image side surface 222 is also curved toward the image plane, and the ratio of the focal length f2 of the second lens 22 to the combined focal length f of the optical imaging system 2 is The second lens 22 is a component made of an optical material with a high refractive index and a low dispersion coefficient, wherein the refractive index nd is greater than 1.6 and the dispersion coefficient vd is less than 30.

[0094] The cross-sectional view of the third lens 23 is as follows: Fig.18 As shown, it has positive refractive power, the third lens 23 has a third lens object side surface 231 and a third lens image side surface 232, the third lens object side surface 231 has a slightly reversed shape, the center portion of which is curved toward the image plane, and the edge portion is curved toward the object side, the third lens image side surface 232 is curved toward the object plane, and the ratio of the focal length f3 of the third lens 23 to the combined focal length f of the optical imaging system 2 is The third lens 23 is a low-refractive-index, high-abbe number optical material component, wherein the refractive index nd is less than 1.58, and the abe number vd is greater than 50.

[0095] The cross-sectional view of the fourth lens 24 is as follows Fig.19 As shown, it has a refractive power, the fourth lens 24 has a fourth lens object side surface 241 and a fourth lens image side surface 242, the fourth lens object side surface 241 and the fourth lens image side surface 242 are curved toward the object plane, and the ratio of the focal length f4 of the fourth lens 24 to the combined focal length f of the optical imaging system 2 is The fourth lens 24 is a component made of an optical material with a high refractive index and a low dispersion coefficient, wherein the refractive index nd is greater than 1.6 and the dispersion coefficient vd is less than 30.

[0096] The cross-sectional view of the fifth lens 25 is as follows: Fig. 20 As shown, it has a diopter, the fifth lens 25 has a fifth lens object side surface 251 and a fifth lens image side surface 252, the fifth lens object side surface 251 is in an inverse shape, the central portion is convex toward the object plane, and the area between the central portion and the edge portion is curved toward the image plane, the fifth lens object side surface 251 and the edge portion of the fifth lens image side surface 252 are all curved toward the object plane, and the shape thereof is an Arabic numeral "3". By designing the inverse shape of the fifth lens 25, it can share a part of the diopter of the sixth lens 26, so that the thickness of the sixth lens 26 can be designed to be thinner, the curved surface design of the fifth lens object side surface 251 is relatively gentle, and the ratio of its sagittal height to the optical clear aperture is less than 0.2, that is, The fifth lens object side surface 251 has a curvature radius R 251 The ratio of the combined focal length f of the optical imaging system 2 is The ratio of the focal length f5 of the fifth lens 25 to the combined focal length f of the optical imaging system 2 is

[0097] The cross-sectional view of the sixth lens 26 is as follows Fig.21 As shown, it has a refractive power, the sixth lens 26 has a sixth lens object side surface 261 and a sixth lens image side surface 262, the sixth lens object side surface 261 has a slightly reversed shape, the center portion of which is curved toward the image plane and convex toward the object plane, while the edge portion is curved toward the object plane, the sixth lens image side surface 262 is curved toward the object plane and convex toward the image plane, and the ratio of the focal length f6 of the sixth lens 26 to the combined focal length f of the optical imaging system 2 is

[0098] The cross-sectional view of the seventh lens 27 is as follows Fig. 22 As shown, it has a refractive power, the seventh lens 27 is thinner in the middle, gradually thickens from the middle to the edge, and then thins again, the ratio of the thickest to the thinnest part of the seventh lens 27 is less than 3, the seventh lens 27 has a seventh lens object side surface 271 and a seventh lens image side surface 272, the central part of the seventh lens object side surface 271 is curved toward the object plane, concave toward the inside of the lens, and the edge part is curved toward the image plane, the central part of the seventh lens image side surface 272 is curved toward the image plane, concave toward the inside of the lens, and the edge part is curved toward the object plane, the seventh lens object side surface 271 and the seventh lens image side surface 272 are both relatively flat, and the ratio of the sagittal height to the aperture is less than 0.2, that is, and

[0099] The optical imaging system 2 of the seven-piece aspherical structure proposed in the second embodiment designs the fifth lens 25 into a reverse curved shape, which can share a part of the refractive power of the sixth lens 26, so that the sixth lens 26 can be thinned. The optical imaging system 2 can control the ratio of the edge thickness to the center thickness of the fourth lens 24, the fifth lens 25 and the sixth lens 26 to within 0.2<DT / DC<4, and also controls the thickness ratio of the seventh lens 27, and can improve the image curvature problem caused by the large sensor size. The optical imaging system 2 can well solve the stray light problem, greatly reduce the tolerance sensitivity of the camera module to the surface error, eccentricity, concentricity and tilt error, and improve the yield rate of the camera module.

[0100] The optical path parameters of the lenses in the optical imaging system 2 of the second embodiment, including the radius of curvature, thickness, refractive index nd, Abbe coefficient Vd, clear aperture, cone coefficient and focal length of each lens are shown in Table 3.

[0101] The first lens 21 has positive refractive power. The first lens 21 is an optical material component with low refractive index and high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In this embodiment 2, its refractive index nd is preferably 1.544502, the Abbe coefficient vd is 55.986991, and the focal length is 5.7430798 mm.

[0102] The second lens 22 has negative refractive power. The second lens 22 is an optical material component with high refractive index and low dispersion coefficient. Its refractive index nd>1.60 and its dispersion coefficient vd<30. In the second embodiment, its refractive index nd=1.661319, Abbe coefficient vd=20.374576, and focal length are preferably -17.3394354 mm.

[0103] The third lens 23 has positive refractive power. The third lens 23 is an optical material component with low refractive index and high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In the second embodiment, its refractive index nd is preferably 1.544502, the Abbe coefficient vd is 55.986991, and the focal length is 9.1200987 mm.

[0104] The fourth lens 24 has a refractive power and is a component of an optical material with a high refractive index and a low dispersion coefficient. Its refractive index nd>1.60 and its dispersion coefficient vd<30. In the second embodiment, its refractive index nd=1.635517, Abbe coefficient vd=23.971841 and focal length are preferably -10.2106903 mm.

[0105] The fifth lens 25 has a refractive power. The fifth lens 25 is an optical material component with a high refractive index and a low dispersion coefficient. Its refractive index nd>1.60 and its dispersion coefficient vd<30. In the second embodiment, its refractive index nd=1.671371, Abbe coefficient vd=19.244900, and focal length are preferably -65.7029839 mm.

[0106] The sixth lens 26 has a refractive power. The sixth lens 26 is an optical material component with a low refractive index and a high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In the second embodiment, its refractive index nd is preferably 1.544502, its Abbe coefficient vd is 55.986991, and its focal length is 2.6088521 mm.

[0107] The seventh lens 27 has a refractive power. The seventh lens 27 is an optical material component with a low refractive index and a high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In the second embodiment, its refractive index nd is preferably 1.544502, its Abbe coefficient vd is preferably 55.986991, and its focal length is -2.2351735 mm.

[0108] Table 3 Optical path parameters of the lens in the optical imaging system 2 of the second embodiment:

[0109]

[0110] The aspheric coefficients of each mirror surface in the optical imaging system 2 of the second embodiment, from the quadratic coefficient a1 to the sixteenth coefficient a8, are shown in Table 4. The aspheric surface is expressed as follows:

[0111]

[0112] Wherein z is the vector height (SAG); c is the curvature, which is the inverse of the radius of curvature; r is the radius of the aspheric aperture; a1, a2, a3... are the various aspheric coefficients.

[0113] Table 4 shows the aspheric coefficients of each mirror surface in the optical imaging system 2 of the second embodiment:

[0114]

[0115]

[0116] The optical path diagram of the optical imaging system 2 of the second embodiment is as follows: Fig.23 As shown, its point diagram is as follows Fig.24 As shown, the minimum root mean square point diagram size of the central field of view is about 1 micron, and the field curvature and distortion curves are as follows Fig.25 As shown, its F-Tan(θ) is controlled within 1.5%, and the design result reaches the expected goal. At the same time, since the fourth lens 24, the fifth lens 25 and the sixth lens 26 are designed to be relatively flat, the image side surface 262 of the sixth lens does not have a particularly protruding part, and the thickest part in the center is no more than 2 times thicker than the thinnest part at the edge, the tolerance sensitivity of the lens is greatly improved, the problem of stray light is also solved, and the yield rate of the camera is improved.

[0117] Embodiment 3

[0118] Please refer to Figure 26 to Figure 32, this embodiment three provides an optical imaging system, the optical imaging system 2 is a seven-piece aspherical structure, including a first lens 21, a second lens 22, a third lens 23, a fourth lens 24, a fifth lens 25, a sixth lens 26, a seventh lens 27, an infrared filter 28 and an image sensor 29 arranged in sequence from the object side to the image side, wherein the second lens 22 and the third lens 23 are glued together by Canadian glue, and the aperture stop is located on the image side surface 212 of the first lens.

[0119] The third embodiment provides an optical imaging system 2, the cross-sectional view of which is shown in FIG. Fig.26 As shown, the combined focal length of the optical imaging system 2 is in the range of 3.65mm<f<7.5mm, and the image plane diagonal size is greater than 6.4mm. In the first embodiment, the combined focal length of the optical imaging system 2 is preferably f=3.8186254mm.

[0120] The cross-sectional view of the first lens 21 is as follows Fig. 27 As shown, it has positive refractive power, the first lens 21 has a first lens object side surface 211 and a first lens image side surface 212, the first lens object side surface 211 and the first lens image side surface 212 are curved toward the image plane, and the ratio of the focal length f1 of the first lens 21 to the combined focal length f of the optical imaging system 2 is The first lens 21 is a low-refractive-index, high-abbe number optical material component, wherein the refractive index nd is less than 1.58, and the abe number vd is greater than 50.

[0121] The second lens 22 and the third lens 23 are glued together to form a set of aspheric glued lenses, the cross-sectional view of which is shown in FIG. Fig.28 As shown, the second lens 22 has a negative refractive power, the center thickness of the second lens 22 is thinner than the edge thickness, the second lens 22 has a second lens object side surface 221 and a second lens image side surface 222, the second lens object side surface 221 is slightly recurved, the center portion of the second lens object side surface 221 is curved toward the image plane, and the edge portion is slightly curved toward the object side; the second lens image side surface 222 is curved toward the image plane, and the ratio of the focal length f2 of the second lens 22 to the combined focal length f of the optical imaging system 2 is The second lens 22 is a component made of an optical material with a high refractive index and a low dispersion coefficient, wherein the refractive index nd is greater than 1.6 and the dispersion coefficient vd is less than 30.

[0122] The third lens 23 has positive refractive power, and has a third lens object side surface 231 and a third lens image side surface 232. The third lens object side surface 231 is the same as the second lens image side surface 222, and the third lens object side surface 231 and the second lens image side surface 222 have the same aspheric coefficient. The third lens object side surface 231 is curved toward the image plane, and the third lens object side surface 231 and the second lens image side surface 222 are glued together by Canadian gum. The third lens image side surface 232 is curved toward the object plane. The ratio of the focal length f3 of the third lens 23 to the combined focal length f of the optical imaging system 2 is The third lens 23 is a low-refractive-index, high-abbe number optical material component, wherein the refractive index nd is less than 1.58, and the abe number vd is greater than 50.

[0123] The cross-sectional view of the fourth lens 24 is as follows Fig.29 As shown, it has a refractive power, the fourth lens 24 has a fourth lens object side surface 241 and a fourth lens image side surface 242, the fourth lens object side surface 241 and the fourth lens image side surface 242 are curved toward the object plane, and the ratio of the focal length f4 of the fourth lens 24 to the combined focal length f of the optical imaging system 2 is The fourth lens 24 is a component made of an optical material with a high refractive index and a low dispersion coefficient, wherein the refractive index nd is greater than 1.6 and the dispersion coefficient vd is less than 30.

[0124] The cross-sectional view of the fifth lens 25 is as follows: Fig.30 As shown, it has a diopter, the fifth lens 25 has a fifth lens object side surface 251 and a fifth lens image side surface 252, the fifth lens object side surface 251 is in an inverse shape, the central portion is convex toward the object plane, and the area between the central portion and the edge portion is curved toward the image plane, the fifth lens object side surface 251 and the edge portion of the fifth lens image side surface 252 are all curved toward the object plane, and the shape thereof is an Arabic numeral "3". By designing the inverse shape of the fifth lens 25, it can share a part of the diopter of the sixth lens 26, so that the thickness of the sixth lens 26 can be designed to be thinner, the curved surface design of the fifth lens object side surface 251 is relatively gentle, and the ratio of its sagittal height to the optical clear aperture is less than 0.2, that is, The fifth lens object side surface 251 has a curvature radius R 251 The ratio of the combined focal length f of the optical imaging system 2 is The ratio of the focal length f5 of the fifth lens 25 to the combined focal length f of the optical imaging system 2 is

[0125] The cross-sectional view of the sixth lens 26 is as follows Fig.31As shown, it has a refractive power, the sixth lens 26 has a sixth lens object side surface 261 and a sixth lens image side surface 262, the sixth lens object side surface 261 has a slightly reversed shape, the center portion of which is curved toward the image plane and convex toward the object plane, while the edge portion is curved toward the object plane, the sixth lens image side surface 262 is curved toward the object plane and convex toward the image plane, and the ratio of the focal length f6 of the sixth lens 26 to the combined focal length f of the optical imaging system 2 is

[0126] The cross-sectional view of the seventh lens 27 is as follows Fig.32 As shown, it has a refractive power, the seventh lens 27 is thinner in the middle, gradually thickens from the middle to the edge, and then thins again, the ratio of the thickest to the thinnest part of the seventh lens 27 is less than 3, the seventh lens 27 has a seventh lens object side surface 271 and a seventh lens image side surface 272, the central part of the seventh lens object side surface 271 is curved toward the object plane, concave toward the inside of the lens, and the edge part is curved toward the image plane, the central part of the seventh lens image side surface 272 is curved toward the image plane, concave toward the inside of the lens, and the edge part is curved toward the object plane, the seventh lens object side surface 271 and the seventh lens image side surface 272 are both relatively flat, and the ratio of the sagittal height to the aperture is less than 0.2, that is, and

[0127] The optical imaging system 2 of the seven-piece aspherical structure proposed in the third embodiment designs the fifth lens 25 into a reverse curved shape, which can share a part of the refractive power of the sixth lens 26, so that the sixth lens 26 can be thinned. The optical imaging system 2 can control the ratio of the edge thickness to the center thickness of the fourth lens 24, the fifth lens 25 and the sixth lens 26 to within 0.2<DT / DC<4, and also controls the thickness ratio of the seventh lens 27, and can improve the image curvature problem caused by the large sensor size. The optical imaging system 2 can well solve the stray light problem, greatly reduce the tolerance sensitivity of the camera module to the surface error, eccentricity, concentricity and tilt error, and improve the yield rate of the camera module.

[0128] The optical path parameters of the lenses in the optical imaging system 2 of the third embodiment, including the radius of curvature, thickness, refractive index nd, Abbe coefficient Vd, clear aperture, cone coefficient and focal length of each lens are shown in Table 5.

[0129] The first lens 21 has positive refractive power. The first lens 21 is an optical material component with low refractive index and high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In this embodiment three, its refractive index nd is preferably 1.544502, the Abbe coefficient vd is 55.986991, and the focal length is 5.3818184 mm.

[0130] The second lens 22 has a negative refractive power. The second lens 22 is an optical material component with a high refractive index and a low dispersion coefficient. Its refractive index nd>1.60 and its dispersion coefficient vd<30. In the third embodiment, its refractive index nd=1.661319, Abbe coefficient vd=20.374576, and focal length are preferably -10.7468271 mm.

[0131] The third lens 23 has positive refractive power. The third lens 23 is an optical material component with low refractive index and high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In this embodiment three, its refractive index nd is preferably 1.544502, the Abbe coefficient vd is 55.986991, and the focal length is 6.4297160 mm.

[0132] The fourth lens 24 has a refractive power. The fourth lens 24 is an optical material component with a high refractive index and a low dispersion coefficient. Its refractive index nd>1.60 and its dispersion coefficient vd<30. In the third embodiment, its refractive index nd=1.661319, Abbe coefficient vd=20.374576 and focal length are preferably -4.7478218 mm.

[0133] The fifth lens 25 has a refractive power. The fifth lens 25 is an optical material component with a low refractive index and a high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In the third embodiment, its refractive index nd is preferably 1.544502, its Abbe coefficient vd is 55.986991, and its focal length is 2.9569209 mm.

[0134] The sixth lens 26 has a refractive power. The sixth lens 26 is an optical material component with a high refractive index and a low dispersion coefficient. Its refractive index nd>1.60 and its dispersion coefficient vd<30. In the third embodiment, its refractive index nd=1.661319, Abbe coefficient vd=20.374576, and focal length are preferably 6.4275854 mm.

[0135] The seventh lens 27 has a refractive power. The seventh lens 27 is an optical material component with a low refractive index and a high dispersion coefficient. Its refractive index nd is less than 1.58, and its dispersion coefficient vd is greater than 50. In this embodiment three, its refractive index nd is preferably 1.544502, the Abbe coefficient vd is 55.986991, and the focal length is -2.3091884 mm.

[0136] Table 5: Optical path parameters of the lens in the optical imaging system 2 of the third embodiment:

[0137]

[0138] The aspheric coefficients of each mirror surface in the optical imaging system 2 of the third embodiment, from the quadratic coefficient a1 to the sixteenth coefficient a8, are shown in Table 6. The aspheric surface is expressed as follows:

[0139]

[0140] Wherein z is the vector height (SAG); c is the curvature, which is the inverse of the radius of curvature; r is the radius of the aspheric aperture; a1, a2, a3... are the various aspheric coefficients.

[0141] Table 6 Aspheric coefficients of each mirror surface in the optical imaging system 2 of the third embodiment:

[0142]

[0143]

[0144] The optical path diagram of the optical imaging system 2 of the third embodiment is as follows: Fig.33 As shown, its point diagram is as follows Fig.34 As shown in the figure, the minimum root mean square point diagram size of the central field of view is about 1.5 microns, and the field curvature and distortion curves are as follows Fig.35 As shown, its F-Tan(θ) is controlled within 1.5%, and the design result reaches the expected goal. At the same time, since the fourth lens 24, the fifth lens 25 and the sixth lens 26 are designed to be relatively flat, the image side surface 262 of the sixth lens does not have a particularly protruding part, and the thickest part in the center is no more than 2 times thicker than the thinnest part at the edge, the tolerance sensitivity of the lens is greatly improved, and the problem of stray light is solved at the same time, thereby improving the yield rate of the camera.

Claims

1. An optical imaging system, characterized in that: The optical imaging system (2) is a seven-piece aspherical structure, comprising a first lens (21), a second lens (22), a third lens (23), a fourth lens (24), a fifth lens (25), a sixth lens (26), a seventh lens (27), an infrared filter (28) and an image sensor (29) which are arranged in sequence from the object side to the image side. The first lens (21) has a positive refractive power; the first lens (21) has a first lens object side surface (211) and a first lens image side surface (212), and the first lens object side surface (211) and the first lens image side surface (212) are both curved toward the image plane; the second lens (22) has a negative refractive power; the center thickness of the second lens (22) is thinner than the edge thickness; the second lens (22) has a second lens object side surface (221) and a second lens image side surface (222), and the center of the second lens object side surface (221) is curved toward the image plane, and the second lens image side surface (222) is curved toward the image plane; the third lens (23) has a positive refractive power. The third lens (23) has a third lens object side surface (231) and a third lens image side surface (232), the central part of the third lens object side surface (231) is curved toward the image plane, and the third lens image side surface (232) is curved toward the object plane; the fourth lens (24) has a negative refractive power; the fourth lens (24) has a fourth lens object side surface (241) and a fourth lens image side surface (242), both of which are curved toward the object plane; the fifth lens (25) has a refractive power, the fifth lens (25) has a fifth lens object side surface (251) and a fifth lens image side surface (252); 52), the object side surface (251) of the fifth lens is in an inverse shape, the central portion is convex toward the object plane, and the area between the central portion and the edge portion is curved toward the image plane. The edge portions of the object side surface (251) of the fifth lens and the image side surface (252) of the fifth lens are all curved toward the object plane, and the shape thereof is an Arabic numeral "3". The sixth lens (26) has a positive refractive power. The sixth lens (26) has a sixth lens object side surface (261) and a sixth lens image side surface (262). The object side surface (261) of the sixth lens has an inverse shape, the central portion thereof is curved toward the image plane, convex toward the object plane, and the edge portion thereof is curved toward the object plane. The image side surface (262) is curved toward the object plane and convex toward the image plane; the seventh lens (27) has a negative refractive power; the seventh lens (27) is thinner in the middle, gradually thickens from the middle to the edge, and then becomes thinner; the ratio of the thickest part to the thinnest part of the seventh lens (27) is less than 3; the seventh lens (27) has a seventh lens object side surface (271) and a seventh lens image side surface (272); the central part of the seventh lens object side surface (271) is curved toward the object plane and concave toward the inside of the lens, while the edge part is curved toward the image plane; the central part of the seventh lens image side surface (272) is curved toward the image plane and concave toward the inside of the lens, while the edge part is curved toward the object plane; The ratio of the edge thickness to the center thickness of the fourth lens (24), the fifth lens (25) and the sixth lens (26) is: 0.2<DT / DC<4; The ratios of the sagitta to the aperture of the object side surface (271) of the seventh lens and the image side surface (272) of the seventh lens are both less than 0.

2.

2. An optical imaging system according to claim 1, characterized in that: The combined focal length of the optical imaging system (2) is in the range of 3.8186254 mm < f < 4.2878353 mm, and the diagonal dimension of the image plane is greater than 6.4 mm.

3. An optical imaging system according to claim 1, characterized in that: The first lens (21) has a first lens object side surface (211) and a first lens image side surface (212), the first lens object side surface (211) and the first lens image side surface (212) are both curved toward the image plane, and the ratio of the focal length f1 of the first lens (21) to the combined focal length f of the optical imaging system (2) is The first lens (21) is a low-refractive-index, high-abbe number optical material component, with a refractive index nd<1.58 and an abe number vd>50.

4. An optical imaging system according to claim 1, characterized in that: The center thickness of the second lens (22) is thinner than the edge thickness, and the ratio of the focal length f2 of the second lens (22) to the combined focal length f of the optical imaging system (2) is The second lens (22) is a component of an optical material with a high refractive index and a low dispersion coefficient, wherein the refractive index nd is greater than 1.6 and the dispersion coefficient vd is less than 30.

5. The optical imaging system according to claim 1, characterized in that: The ratio of the focal length f3 of the third lens (23) to the combined focal length f of the optical imaging system (2) is The third lens (23) is a low-refractive-index, high-abbe number optical material component, with a refractive index nd<1.58 and an abe number vd>50.

6. An optical imaging system according to claim 1, characterized in that: The fourth lens (24) has a fourth lens object side surface (241) and a fourth lens image side surface (242), the fourth lens object side surface (241) is curved toward the object plane, and the ratio of the focal length f4 of the fourth lens (24) to the combined focal length f of the optical imaging system (2) is The fourth lens (24) is a component of an optical material with a high refractive index and a low dispersion coefficient, wherein the refractive index nd is greater than 1.6 and the dispersion coefficient vd is less than 30.

7. An optical imaging system according to claim 1, characterized in that: The fifth lens (25) has a fifth lens object side surface (251) and a fifth lens image side surface (252), the ratio of the sagittal height of the fifth lens object side surface (251) to the optical clear aperture is less than 0.2, and the curvature radius R 251 The ratio of the combined focal length f of the optical imaging system (2) is The ratio of the focal length f5 of the fifth lens (25) to the combined focal length f of the optical imaging system (2) is 8. An optical imaging system according to claim 1, characterized in that: The ratio of the focal length f6 of the sixth lens (26) to the combined focal length f of the optical imaging system (2) is

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