Large-aperture optical system and camera module applying same

Abstract

The invention provides a large-aperture optical system and a camera module applying the same, the large-aperture optical system is mainly composed of five lenses, the object plane side of the first lens is a convex surface, the image plane side is a concave surface, and the focal power of the first lens is negative; the object plane side of the second lens is a concave surface, the image plane side is a convex surface, and the focal power is positive; the object surface side and the image surface side of the third lens are convex surfaces, and the focal power of the third lens is positive; the object plane side and the image plane side of the fourth lens are concave surfaces, and the focal power of the fourth lens is negative; the object surface side and the image surface side of the fifth lens are convex surfaces, and the focal power of the fifth lens is positive; the lens is reasonable in number and simple in structure, the imaging quality of an optical system is improved by reasonably distributing the focal power of the lenses and optimizing the aberration of the lens, the characteristics of ultra-wide angle, high illumination, day and night confocal and excellent temperature characteristic are considered, and the lens has huge potential in the IPC market.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical imaging, in particular to a large-aperture optical system and a camera module using the same. BACKGROUND

[0002] With the progress of science and technology and the development of social economy, camera lenses are widely used in various fields, especially in the field of security monitoring. However, the previous camera lenses or optical systems have defects such as low pixel, small field of view, poor day and night effect, and small light quantity, which are difficult to meet the needs of users. SUMMARY

[0003] In order to overcome the technical problems of low pixel, small field of view, poor day and night effect, and small light quantity of the existing optical lenses, the present application provides a large-aperture optical system. By reasonably distributing the surface shape and optical power of each lens, the lens aberration is optimized, and the optical system has excellent resolving power, high pixel, large aperture, no thermalization, day and night focusing, light weight, and other characteristics, and has greater competitiveness in the IPC market.

[0004] An optical system, sequentially comprising a first lens, a second lens, a third lens, a fourth lens and a fifth lens from an object plane to an image plane along an optical axis: The object side of the first lens is convex, and the image side is concave, and the optical power is negative; The object side of the second lens is concave, and the image side is convex, and the optical power is positive; The object side and the image side of the third lens are both convex, and the optical power is positive; The object side and the image side of the fourth lens are both concave, and the optical power is negative; The object side and the image side of the fifth lens are both convex, and the optical power is positive.

[0005] Preferably, each lens of the optical system satisfies the following conditions: -13.5mm < f1 < -3.2mm; 50mm < f2 < 200mm; 4.5mm < f3 < 8.2mm; -6.5mm < f4 < -3.5mm; 3.1mm < f5 < 7.5mm; Wherein, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens.

[0006] Preferably, each lens of the optical system satisfies the following conditions: Nd1 > 1.7, Vd1 < 56; Nd2 > 1.6, Vd2 < 30; Nd3>1.51, Vd3<75; Nd4>1.6, Vd4<30; Nd5>1.51, Vd5<60; Wherein, Nd1 is the refractive index of the first lens, Vd1 is the Abbe number of the first lens; Nd2 is the refractive index of the second lens, Vd2 is the Abbe number of the second lens; Nd3 is the refractive index of the third lens, Vd3 is the Abbe number of the third lens; Nd4 is the refractive index of the fourth lens, Vd4 is the Abbe number of the fourth lens; Nd5 is the refractive index of the fifth lens, Vd5 is the Abbe number of the fifth lens.

[0007] Preferably, the relative luminance of the maximum field of view of the optical system satisfies: RI ≥ 30%.

[0008] Preferably, the radius of curvature R1 of the object side of the first lens satisfies: R1 ≤ 30mm.

[0009] Preferably, the total optical length TTL and the aperture FNO of the optical system satisfy: TTL ≤ 23 mm, FNO ≤ 1.7.

[0010] Preferably, the third lens is a glass lens.

[0011] Preferably, the horizontal field angle FOV of the optical system satisfies: FOV ≥ 145°, and the maximum image circle MIC satisfies: MIC ≥ 6.9mm.

[0012] Preferably, the diaphragm is arranged between the second lens and the third lens.

[0013] Preferably, the fourth lens and the fifth lens are bonded to form a combined lens.

[0014] In another aspect, the embodiment of the present application also provides a camera module, which at least comprises an optical lens, and the optical lens is internally mounted with the lens optical system described above.

[0015] Compared with the prior art, the beneficial effects of the present application are as follows: The present application provides a large-aperture optical system and a camera module using the same, which is mainly composed of six lenses, the number of lenses is reasonable, the structure is simple, the lens power is reasonably distributed, the lens aberration is optimized, the imaging quality of the optical system is improved, and the characteristics of ultra-wide angle, high luminance, day and night focusing, and excellent temperature characteristics are considered, which has great potential in the IPC market. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows.

[0017] Figure 1 is a structural schematic diagram of an optical system or camera module of Embodiment 1 of the present application; Figure 2 is a curve graph of astigmatism and distortion of the optical system or camera module of Embodiment 1 of the present application; Figure 3 is a curve graph of MTF of the optical system or camera module of Embodiment 1 of the present application; Figure 4 is a structural schematic diagram of an optical system or camera module of Embodiment 2 of the present application; Figure 5 is a curve graph of astigmatism and distortion of the optical system or camera module of Embodiment 2 of the present application; Figure 6 is a curve graph of MTF of the optical system or camera module of Embodiment 2 of the present application; Figure 7 is a structural schematic diagram of an optical system or camera module of Embodiment 3 of the present application; Figure 8 is a curve graph of astigmatism and distortion of the optical system or camera module of Embodiment 3 of the present application; Figure 9 is a curve graph of MTF of the optical system or camera module of Embodiment 3 of the present application. DETAILED DESCRIPTION

[0018] As shown in Figures 1-9 , the present application provides a large aperture optical system, which is composed of a first lens 1, a second lens 2, a stop STO, a third lens 3, a fourth lens 4, a fifth lens 5, and an infrared filter 6 in sequence along the optical axis from the object plane to the image plane.

[0019] The object plane side S1 of the first lens 1 is a convex surface, and the image plane side S2 is a concave surface, with a negative refractive power; The object plane side S3 of the second lens 2 is a concave surface, and the image plane side S4 is a convex surface, with a positive refractive power; The object plane side S5 and the image plane side S6 of the third lens 3 are both convex surfaces, with a positive refractive power; The object plane side S7 and the image plane side S8 of the fourth lens 4 are both concave surfaces, with a negative refractive power; The object plane side S8 and the image plane side S9 of the fifth lens 5 are both convex surfaces, with a positive refractive power; The application provides a large-aperture optical system and an application camera module thereof, which mainly comprises five lenses.

[0020] Further, as a preferred embodiment of the application but not limited, each lens of the optical system satisfies the following conditions, wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens: -13.5 mm < f1 < -3.2 mm, which can make the first lens 1 have a large negative focal length, and is beneficial to reduce the astigmatism and field curvature of the optical system; 50 mm < f2 < 200 mm, by limiting the ratio of the focal length of the second lens 2 to the effective focal length of the optical imaging system in a reasonable range, the spherical aberration of the system is fine-tuned and controlled, and the imaging quality of the system is effectively improved; 4.5 mm < f3 < 8.2 mm, by limiting the ratio of the focal length of the third lens 3 to the effective focal length of the optical imaging system in a reasonable range, the optical system has the advantages of super wide angle, large aperture, small volume and excellent temperature characteristics; -6.5 mm < f4 < 3.5 mm, by limiting the ratio of the focal length of the fourth lens 4 to the effective focal length of the optical imaging system in a reasonable range, the spherical aberration of the system is fine-tuned and controlled, and the imaging quality of the system is effectively improved; 3.1 mm < f5 < 7.5 mm, by limiting the ratio of the focal length of the fifth lens 5 to the effective focal length of the optical imaging system in a reasonable range, the optical system has the advantages of super wide angle, large aperture, small volume and excellent temperature characteristics; Further, the refractive index Nd1 and Abbe number Vd1 of the first lens 1 satisfy: Nd1 > 1.7, Vd1 < 56, which can effectively reduce chromatic aberration, optimize lens aberration, and effectively improve the imaging quality of the system; Further, the refractive index Nd2 and Abbe number Vd2 of the second lens 2 satisfy: Nd2 > 1.6, Vd2 < 20, which can effectively reduce chromatic aberration, optimize lens aberration, and effectively improve the imaging quality of the system; Further, the third lens 3 has a refractive index Nd3 and an Abbe number Vd3, and Nd3>1.51 and Vd3<75, which can effectively reduce chromatic aberration, optimize lens aberration, and improve the imaging quality of the system. Further, the fourth lens 4 has a refractive index Nd4 and an Abbe number Vd4, and Nd4<1.6 and Vd4<30, which can effectively reduce chromatic aberration, optimize lens aberration, and improve the imaging quality of the system. Further, the fifth lens 5 has a refractive index Nd5 and an Abbe number Vd5, and Nd5>1.51 and Vd5<60, which can effectively reduce chromatic aberration, optimize lens aberration, and improve the imaging quality of the system. Further, as a preferred embodiment of the present application, the relative illumination of the maximum field of view of the optical system satisfies RI≥30%, which can improve the brightness of the edge field of view of the lens by controlling the relative illumination. Further, as a preferred embodiment of the present application, the curvature radius R1 of the object side of the first lens satisfies R1≤30mm, which can reasonably control the total deflection angle of the object side of the first lens 1 at the edge field of view within a reasonable range.

[0021] Further, as a preferred embodiment of the present application, the third lens is glass, which can effectively improve the focal point shift at high and low temperatures.

[0022] Further, as a preferred embodiment of the present application, the optical total length TTL and the aperture FNO of the optical system satisfy TTL≤23mm and FNO≤1.7, which can reduce the optical total length, effectively miniaturize the lens, and increase the light amount of the system.

[0023] Further, as a preferred embodiment of the present application, the horizontal field angle FOV of the optical system satisfies FOV≥145°, and the maximum image circle MIC satisfies MIC≥6.9mm, which is beneficial to expand the field of view and meet the user's use demand. Further, as a preferred embodiment of the present application, the fourth lens and the fifth lens are adhered to each other to form a combined lens, which can effectively reduce chromatic aberration by increasing the difference between the refractive index and the Abbe number of the lens.

[0024] Specifically, as a preferred embodiment of the present application, as shown in Figures 1-3In the embodiment 1, the focal length f1 of the first lens 1 is -4.85mm, the focal length f2 of the second lens 2 is 165mm, the focal length f3 of the third lens 3 is 6.19mm, the focal length f4 of the fourth lens 4 is -5.25mm, the focal length f5 of the fifth lens 5 is 4.95mm, and the total track length TTL is 22.679mm. The surface type, the radius of curvature, the thickness and the material parameters of each lens are shown in Table 1. Table 1: Basic parameters of the optical system in embodiment 1

[0025] In Table 1, along the optical axis from the object plane to the image plane, OBJ is the object plane; S1 and S2 correspond to the two surfaces of the first lens 1; S3 and S4 correspond to the two surfaces of the second lens 2; S5 and S6 correspond to the two surfaces of the third lens 3; S7 and S8 correspond to the two surfaces of the fourth lens 4; S8 and S9 correspond to the two surfaces of the fifth lens 5; STO is the position of the stop; S10 and S11 correspond to the two surfaces of the filter; and IMA corresponds to the image plane.

[0026] Further, in Table 1, the surface type of each aspheric lens can be defined by, but not limited to, the following aspheric formula:

[0027] wherein x is the distance from the corresponding point on the aspheric surface to the plane tangent to the vertex of the surface, h is the distance from the corresponding point on the aspheric surface to the optical axis, c is the curvature of the vertex of the aspheric surface, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th high-order term in the aspheric surface formula. Table 2 shows the conic coefficients and high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of each aspheric surface that can be used in embodiment 1.

[0028] Table 2: Aspheric surface related values of the lenses in embodiment 1

[0029] Figure 2 The astigmatism and distortion curves of the optical imaging lens in embodiment 1 are shown, wherein the astigmatism represents the meridional image surface curvature and the sagittal image surface curvature, and the distortion represents the distortion size value corresponding to different image heights; Figure 3 The MTF curve of the optical imaging lens in embodiment 1 is shown, which represents the MTF values in the meridional direction and the sagittal direction of different fields of view under different spatial frequencies, and the MTF values are shown in Table 3. Figure 2 and Figure 3 It can be seen that the optical imaging system in embodiment 1 can achieve good imaging quality and has higher imaging quality.

[0030] In particular, as a preferred embodiment of the present application but not limited, as shown in Table 1, in the first embodiment, the focal length f1 of the first lens 1 is -5.17 mm, the focal length f2 of the second lens 2 is 142 mm, the focal length f3 of the third lens 3 is 5.96 mm, the focal length f4 of the fourth lens 4 is -4.18 mm, the focal length f5 of the fifth lens 5 is 4.41 mm, the total optical length TTL is 22.676 mm, and the surface type, curvature radius, thickness and material parameters of each lens are shown in Table 2: Figures 4-6 Table 2: Basic parameters of the optical system of embodiment 1

[0031] In Table 2, along the optical axis from the object plane to the image plane, OBJ is the object plane; S1 and S2 correspond to the two surfaces of the first lens 1; S3 and S4 correspond to the two surfaces of the second lens 2; S5 and S6 correspond to the two surfaces of the third lens 3; S7 and S8 correspond to the two surfaces of the fourth lens 4; S8 and S9 correspond to the two surfaces of the fifth lens 5; STO is the position of the stop; S10 and S11 correspond to the two surfaces of the filter; and IMA corresponds to the image plane.

[0032] Further, the surface type of each aspheric lens can be defined by, but not limited to, the following aspheric formula:

[0033] Wherein, x is the distance from the corresponding point on the aspheric surface to the plane tangent to the surface vertex, h is the distance from the corresponding point on the aspheric surface to the optical axis, c is the curvature of the aspheric vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th high-order term in the aspheric surface formula. Table 3 gives the conic coefficients and high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspheric surfaces that can be used in embodiment 2.

[0034] Table 3: Aspheric surface related values of the lenses in embodiment 2

[0035] Figure 5 The astigmatism and distortion curves of the optical imaging lens of embodiment 2 are shown, where the astigmatism represents the meridional image surface curvature and sagittal image surface curvature, and the distortion represents the distortion size value corresponding to different image heights; Figure 6 The MTF curve of the optical imaging lens of embodiment 2 is shown, which represents the MTF values in the meridional direction and the sagittal direction of different fields of view under different spatial frequencies, as shown in Figure 5 and Figure 6 It can be seen that the optical imaging system of embodiment 2 can achieve good imaging quality and has higher imaging quality. ​

[0036] Specifically, this is a preferred embodiment of the invention and not a limitation thereof, such as Figures 7-9 As shown, in this embodiment 3, the focal length of the first lens 1 is f1 = -5.74mm, the focal length of the second lens 2 is f2 = 130mm, the focal length of the third lens 3 is f3 = 6.33mm, the focal length of the fourth lens 4 is f4 = -4.15mm, the focal length of the fifth lens 5 is f5 = 4.33mm, and the total optical length TTL is 22.679mm. The surface type, radius of curvature, thickness, and material parameters of each lens are shown in Table 5. Table 5: Basic parameters of the optical system in Example 3

[0037] In Table 5 above, along the optical axis from the object plane to the image plane, OBJ is the object plane; S1 and S2 correspond to the two surfaces of the first lens 1; S3 and S4 correspond to the two surfaces of the second lens 2; S5 and S6 correspond to the two surfaces of the third lens 3; S7 and S8 correspond to the two surfaces of the fourth lens 4; S8 and S9 correspond to the two surfaces of the fifth lens 5; STO is the location of the aperture stop; S10 and S11 correspond to the two surfaces of the filter; IMA corresponds to the image plane.

[0038] Furthermore, in Table 5, the object-side surface and image-side surface of any one of the second lens 2, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are aspherical. The surface shape of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0039] Where x is the distance from the corresponding point on the aspherical surface to the plane tangent to the vertex of the surface, h is the distance from the corresponding point on the aspherical surface to the optical axis, c is the curvature of the vertex of the aspherical surface, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th higher-order term in the aspherical surface shape formula. Table 6 gives the conic coefficients and higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 of each aspherical surface that can be used in Example 3.

[0040] Table 6: Aspherical Correlation Values ​​of Lens Surface in Example 3

[0041] Figure 8 The astigmatism and distortion curves of the optical imaging lens in Example 3 are shown. Astigmatism represents the curvature of the meridional image plane and the curvature of the sagittal image plane, and distortion represents the magnitude of distortion at different image heights. Figure 9 The MTF curve of the optical imaging lens of Example 3 is shown, which represents the MTF values ​​in the meridional and sagittal directions of different fields of view at different spatial frequencies. Figure 8 andFigure 9 It can be seen that the optical imaging system given in embodiment 3 can achieve good imaging quality and has higher imaging quality.

[0042] Further, in embodiments 1-3, the basic data are as follows: Table 7: Basic data of embodiments 1-3

[0043] A camera module at least includes an optical lens, and an optical system is sequentially composed of a first lens, a second lens, a third lens, a fourth lens and a fifth lens from an object plane to an image plane along an optical axis. By reasonably distributing the surface shape and optical power of each lens, the lens aberration is optimized, and the lens has excellent resolving power, high pixels, large aperture, no thermalization, day and night confocal, light weight and other characteristics, and has greater competitiveness in the IPC market.

[0044] The above is one or more embodiments provided in combination with specific content, and it is not intended that the specific implementation of the present application is limited to these descriptions. Any approximation, similarity or replacement of the method and structure of the present application, or any technical deduction or replacement made on the basis of the concept of the present application, should be considered as the protection scope of the present application.

Claims

1. A large aperture optical system, sequentially comprising a first lens, a second lens, a third lens, a fourth lens and a fifth lens from an object plane to an image plane along an optical axis, characterized in that: the object plane side of the first lens is convex, the image plane side of the first lens is concave, and the focal power of the first lens is negative; the object plane side of the second lens is concave, the image plane side of the second lens is convex, and the focal power of the second lens is positive; the object plane side and the image plane side of the third lens are both convex, and the focal power of the third lens is positive; the object plane side and the image plane side of the fourth lens are both concave, and the focal power of the fourth lens is negative; the object plane side and the image plane side of the fifth lens are both convex, and the focal power of the fifth lens is positive; each lens of the optical system satisfies the following conditions: -13.5mm < f1 < -3.2mm; 50mm < f2 < 200mm; 4.5mm < f3 < 8.2mm; -6.5mm < f4 < -3.5mm; 3.1mm < f5 < 7.5mm; wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens. each lens of the optical system satisfies the following conditions: Nd1 > 1.7, Vd1 < 56; Nd2 > 1.6, Vd2 < 30; Nd3 > 1.51, Vd3 < 75; Nd4 > 1.6, Vd4 < 30; Nd5 > 1.51, Vd5 < 60; wherein Nd1 is the refractive index of the first lens, Vd1 is the Abbe number of the first lens; Nd2 is the refractive index of the second lens, Vd2 is the Abbe number of the second lens; Nd3 is the refractive index of the third lens, Vd3 is the Abbe number of the third lens; Nd4 is the refractive index of the fourth lens, Vd4 is the Abbe number of the fourth lens; and Nd5 is the refractive index of the fifth lens, Vd5 is the Abbe number of the fifth lens. the relative luminance of the maximum field of view of the optical system satisfies: RI ≥ 30%. the curvature radius R1 of the object plane side of the first lens satisfies: R1 ≤ 30mm. the total optical length TTL and the aperture of the optical system satisfy: TTL ≤ 23mm, FNO ≤ 1.

7. the third lens is a glass lens. the horizontal field angle FOV of the optical system satisfies: FOV ≥ 145°, and the maximum image circle MIC satisfies: MIC ≥ 6.9mm. a diaphragm is arranged between the second lens and the third lens. the fourth lens and the fifth lens are adhered to each other to form a combined lens. the optical lens is provided with the optical system according to any one of claims 1-9. ​ ​ ​ 2. The high-aperture optical system according to claim 1, characterized by: ​ ​ ​ ​ ​ ​ ​ 3. The high-aperture optical system according to any one of claims 1 to 3, characterized by: ​ 4. The high-aperture optical system according to any one of claims 1 to 3, characterized by: ​ 5. The high-aperture optical system according to any one of claims 1 to 3, characterized by: ​ 6. The high-aperture optical system according to any one of claims 1 to 3, characterized by: ​ 7. The high-aperture optical system according to any one of claims 1 to 3, characterized by: ​ 8. The high-aperture optical system according to claim 1, characterized by: ​ 9. The high-aperture optical system according to claim 1, characterized by: ​ 10. An image capturing module comprising at least an optical lens, characterized in that: ​

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