Large-aperture day and night confocal optical system and camera module applying same

Abstract

The invention provides a large-aperture day and night confocal optical system and a camera module applying the same, the large-aperture day and night confocal optical system is mainly composed of six lenses, the object plane side of the first lens is a convex surface, the image plane side is a concave surface, 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, the focal power of the second lens is positive, the object plane side of the third lens is a convex surface, the image plane side is a convex surface, and the focal power of the third lens is positive. The focal power of the sixth lens is positive, the fourth lens has focal power, the fifth lens has focal power, the object plane side of the sixth lens is a convex surface, the image plane side of the sixth lens is a convex surface or a concave surface, the focal power is positive, the number of the lenses is reasonable, the structure is simple, through reasonable distribution of the surface types and the focal power of all the lenses, the lens aberration is optimized, and the imaging quality of the optical system is improved. The characteristics of ultra-wide angle, high illumination, day and night confocal property and excellent temperature property are considered, and the wide-angle lens has huge potential in the IPC market.

Description

Technical Field

[0001] The present application relates to the field of optical imaging, and in particular to a large-aperture day-night confocal optical system and a camera module used therein. Background Art

[0002] With the advancement of science and technology and social and economic development, camera modules have been widely used in various fields, especially in the field of security monitoring. However, previous camera modules or optical systems have defects such as low pixels, small field of view, poor day and night effects, and low light input, which make it difficult to meet the needs of users. Summary of the Invention

[0003] In order to overcome the technical problems of existing optical lenses such as low pixels, small field of view, poor day and night effects, and small amount of light entering, the present application provides a day and night confocal optical system. By rationally distributing the surface shape and optical focal length of each lens, it optimizes lens aberrations and has the characteristics of excellent resolution, high pixels, large aperture, athermalization, day and night confocality, light weight, etc., which makes it more competitive in the IPC market.

[0004] To achieve the purpose, the present invention adopts the following technical solutions: A large aperture day and night confocal optical system, which is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens in sequence from the object plane to the image plane along the optical axis; The object side of the first lens is convex, the image side is concave, and its optical power is negative; The object side of the second lens is concave, the image side is convex, and its optical power is positive; The object side and image side of the third lens are convex, and its optical power is positive; The fourth lens has optical power; The fifth lens has optical power; The object side of the sixth lens is convex, the image side is convex or concave, and its optical power is positive.

[0005] For the large aperture day and night confocal optical system described above, each lens of the optical system meets the following conditions: -7.5mm<f1<-3.5mm; 5mm<f2<100mm; 4.5mm<f3<10.3mm; -7.3mm<f4<9.2mm; -6.5mm<f5<5.2mm; 5.1mm<f6<29mm; Among them, 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, f5 is the focal length of the fifth lens, and f6 is the focal length of the sixth lens.

[0006] For the large aperture day and night confocal optical system described above, each lens of the optical system meets the following conditions: Nd1>1.71,Vd1<63; Nd2>1.62,Vd2<30; Nd3>1.55,Vd3<72; Nd4>1.45,Vd4<60; Nd5>1.45,Vd5<60; Nd6>1.45,Vd6<60; Wherein, Nd1 is the refractive index of the first lens element, and Vd1 is the Abbe number of the first lens element; Nd2 is the refractive index of the second lens element, and Vd2 is the Abbe number of the second lens element; Nd3 is the refractive index of the third lens element, and Vd3 is the Abbe number of the third lens element; Nd4 is the refractive index of the fourth lens element, and Vd4 is the Abbe number of the fourth lens element; Nd5 is the refractive index of the fifth lens element, and Vd5 is the Abbe number of the fifth lens element; Nd6 is the refractive index of the sixth lens element, and Vd6 is the Abbe number of the sixth lens element.

[0007] For the large aperture day and night confocal optical system as described above, the relative illumination of the maximum field of view of the optical system satisfies: RI ≥ 45%.

[0008] In the large aperture day and night confocal optical system described above, the curvature radius R1 of the object surface side of the first lens satisfies: R1 > 20 mm.

[0009] For the large aperture day and night confocal optical system as described above, the total optical length TTL of the system satisfies: TTL ≤ 23.5 mm.

[0010] In the large aperture day and night confocal optical system as described above, the third lens is a glass lens.

[0011] For the large aperture day and night confocal optical system as described above, the horizontal field angle FOV of the optical system satisfies: FOV≥140°, and the maximum image circle satisfies: MIC≥6.9mm.

[0012] In the large aperture day and night confocal optical system as described above, the aperture is arranged between the second lens and the third lens.

[0013] In the large aperture day and night confocal optical system as described above, the fourth lens and the fifth lens are cemented together to form a combined lens.

[0014] On the other hand, an embodiment of the present application also provides a camera module, in which the above-mentioned large aperture day and night confocal optical system is installed.

[0015] Compared with the prior art, the present invention has the following advantages: The present invention provides a large-aperture day-night confocal optical system and a camera module used therein. The system is mainly composed of six lenses, with a reasonable number of lenses and a simple structure. By rationally allocating the surface shape and optical power of each lens, lens aberrations are optimized, and the imaging quality of the optical system is improved. The system has the characteristics of ultra-wide angle, high illumination, day-night confocality, and excellent temperature characteristics, and has great potential in the IPC market. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments.

[0017] Figure 1 Schematic diagram of the structure of the optical system or camera module of Example 1 of the present application; Figure 2 1 is a graph showing field curvature and distortion of the optical system or camera module according to Example 1 of the present application; Figure 3 is an MTF curve diagram of the optical system or camera module of Example 1 of the present application; Figure 4 2 is a schematic structural diagram of an optical system or camera module according to embodiment 2 of the present application; Figure 5 2 is a graph showing field curvature and distortion of the optical system or camera module according to Example 2 of the present application; Figure 6 : is an MTF curve diagram of the optical system or camera module of Example 2 of the present application; Figure 7 Schematic diagram of the structure of the optical system or camera module according to Example 3 of the present application; Figure 8 3 is a graph showing field curvature and distortion of the optical system or camera module according to Example 3 of the present application; Figure 9 This is the MTF curve diagram of the optical system or camera module of Example 3 of the present application. DETAILED DESCRIPTION

[0018] like Figure 1-9 As shown, the present application provides a large aperture day and night confocal optical system, which is composed of a first lens E1, a second lens E2, an aperture STO, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, and an infrared filter E7 along the optical axis from the object plane to the image plane.

[0019] The first lens E1 has a convex object side and a concave image side, and its refractive power is negative. The second lens E2 has a concave object side and a convex image side, and has positive refractive power. The third lens E3 has a convex object side surface and a convex image side surface, and its optical power is positive; The fourth lens E4 has optical power; The fifth lens E5 has optical power; The sixth lens E6 has a convex object-side surface and a convex or concave image-side surface, and has positive refractive power. The optical system of the embodiment of the present invention is mainly composed of 6 lenses. The number of lenses is reasonable and the structure is simple. By rationally distributing the optical power of the lenses and optimizing the lens aberrations, the imaging quality of the optical system is improved. It takes into account the characteristics of ultra-wide angle, high illumination, day and night confocality, and excellent temperature characteristics. It has great potential in the IPC market.

[0020] Furthermore, as a preferred embodiment of the present invention but not limiting, 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, f5 is the focal length of the fifth lens, and f6 is the focal length of the sixth lens: -7.5 mm<f1<-3.5 mm. This design allows the first lens E1 to have a large negative focal power, which helps reduce astigmatism and field curvature of the optical system. 5mm<f2<100mm, by constraining the ratio of the optical power of the second lens E2 to the effective focal length of the optical imaging system within a reasonable range, the spherical aberration of the system is fine-tuned and controlled, thereby effectively improving the imaging quality of the system; 4.5mm<f3<10.3mm. By constraining the ratio of the optical power of the third lens E3 to the effective focal length of the optical imaging system within a reasonable range, the optical system has the advantages of ultra-wide angle, large aperture, small size, and excellent temperature characteristics. -7.3mm<f4<9.2mm. By constraining the ratio of the optical power of the fourth lens E4 to the effective focal length of the optical imaging system within a reasonable range, the spherical aberration of the system is fine-tuned and controlled, thereby effectively improving the imaging quality of the system. -6.5mm<f5<5.2mm. By limiting the ratio of the fifth lens's E5 focal length to the effective focal length of the optical imaging system to a reasonable range, the optical system has the advantages of ultra-wide angle, large aperture, compact size, and excellent temperature characteristics. 5.1mm<f6<29mm. By constraining the ratio of the sixth lens's E6 focal length to the effective focal length of the optical imaging system to a reasonable range, the configured optical system has the advantages of ultra-wide angle, small aperture, high illumination, and excellent temperature characteristics. It also has a compact structure and is easy to process and install. At the same time, the large aperture configuration can increase the amount of light entering the optical system and achieve higher imaging quality.

[0021] Furthermore, the refractive index Nd1 and Abbe number Vd1 of the first lens element E1 satisfy the following conditions: Nd1>1.71, Vd1<63. This design can effectively reduce chromatic aberration, optimize lens aberrations, and thereby effectively improve the imaging quality of the system. Furthermore, the refractive index Nd2 and Abbe number Vd2 of the second lens element E2 satisfy: Nd2>1.62, Vd2<30. This design can effectively reduce chromatic aberration, optimize lens aberrations, and thus effectively improve the imaging quality of the system. Furthermore, the refractive index Nd3 and Abbe number Vd3 of the third lens element E3 satisfy the following conditions: Nd3>1.55, Vd3<72. This design can effectively reduce chromatic aberration, optimize lens aberrations, and thereby effectively improve the imaging quality of the system. Furthermore, the refractive index Nd4 and Abbe number Vd4 of the fourth lens element E4 satisfy the following conditions: Nd4>1.45, Vd4<60. This design can effectively reduce chromatic aberration, optimize lens aberrations, and thereby effectively improve the imaging quality of the system. Furthermore, the refractive index Nd5 and Abbe number Vd5 of the fifth lens element E5 satisfy the following requirements: Nd5>1.45, Vd5<60. This design can effectively reduce chromatic aberration, optimize lens aberrations, and thus effectively improve the imaging quality of the system. Furthermore, the refractive index Nd6 and Abbe number Vd6 of the sixth lens element E6 satisfy the following conditions: Nd6>1.45, Vd6<60. This design can effectively reduce chromatic aberration, optimize lens aberrations, and thereby effectively improve the imaging quality of the system. Furthermore, as a preferred embodiment of the present invention but not limiting, the relative illumination of the maximum field of view of the optical system satisfies: RI ≥ 45%. By controlling the relative illumination, the brightness of the peripheral field of view of the lens can be improved; Furthermore, as a preferred embodiment of the present invention but not a limitation thereof, the curvature radius R1 of the object side of the first lens E1 satisfies: R1 > 20 mm. By controlling the object side of the first lens E1, the total deflection angle of the object side of the first lens 1 at the edge of the field of view can be reasonably controlled to be within a reasonable range.

[0022] Furthermore, as a preferred embodiment of the present invention but not limitation, the third lens is made of glass, which can effectively improve the focus offset under high and low temperature conditions.

[0023] Furthermore, as a preferred embodiment of the present invention but not a limitation, the total optical length TTL of the optical system satisfies: TTL ≤ 23.5 mm. This design can reduce the total optical length and effectively miniaturize the lens.

[0024] Furthermore, as a preferred embodiment of the present invention but not limiting, the horizontal field angle FOV of the optical system satisfies: FOV ≥ 140°, and the maximum image circle satisfies: MIC ≥ 6.9 mm, which is conducive to expanding the field of view and meeting user needs; Furthermore, as a preferred embodiment of the present invention but not a limitation, the fourth lens and the fifth lens are bonded together to form a combined lens. This design increases the difference between the refractive index and the Abbe number of the lens, which can effectively reduce chromatic aberration.

[0025] Specifically, as a preferred embodiment of the present invention but not limiting, Figure 1-3 As shown, in this embodiment 1, the focal length f1 of the first lens 1 is -5.1 mm, the focal length f2 of the second lens 2 is 12.8 mm, the focal length f3 of the third lens 3 is 6.4 mm, the focal length f4 of the fourth lens 4 is -3.1 mm, the focal length f5 of the fifth lens 5 is 4 mm, the focal length f6 of the sixth lens 6 is 24.6 mm, and the total optical length TTL is 22.69 mm. The surface type, curvature radius, thickness and material parameters of each lens are shown in Table 1: Table 1: Basic parameters of the optical system of Example 1

[0026] In Table 1 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 E1; S3 and S4 correspond to the two surfaces of the second lens E2; S6 and S7 correspond to the two surfaces of the third lens E3; S8 and S9 correspond to the two surfaces of the fourth lens E4; S9 and S10 correspond to the two surfaces of the fifth lens E5; S11 and S12 correspond to the two surfaces of the sixth lens E6; STO is the location of the aperture; S13 and S14 correspond to the two surfaces of the filter E7; and IMA corresponds to the image plane.

[0027] Furthermore, in Table 1, any one of the object side and image side of the second lens E2, the third lens E4, the fifth lens E5, and the sixth lens E6 is an aspherical surface. The surface shape of each aspherical lens can be defined by, but not limited to, the following aspherical surface formula:

[0028] Where 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 aspheric vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th higher-order term in the aspheric surface shape formula. Table 2 shows the conic coefficients and higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 for various aspheric surfaces that can be used in Example 1.

[0029] Table 2: Aspheric surface related values ​​of the lens surface of Example 1

[0030] Figure 2 The astigmatism and distortion curves of the optical imaging lens of Example 1 are shown. Astigmatism represents meridional image curvature and sagittal image curvature, and distortion represents the distortion magnitude corresponding to different image heights. Figure 3 The MTF curve of the optical imaging lens of Example 1 is shown, which represents the MTF values ​​in the meridian and sagittal directions of different fields of view at different spatial frequencies. Figure 2 and Figure 3 It can be seen that the optical imaging system provided in Example 1 can achieve good imaging quality and has higher imaging quality.

[0031] Specifically, as another preferred embodiment of the present invention but not limiting, Figure 4-6 As shown, in this embodiment 2, the focal length f1 of the first lens element E1 is -5.9 mm, the focal length f2 of the second lens element E2 is 73.2 mm, the focal length f3 of the third lens element E3 is 7.1 mm, the focal length f4 of the fourth lens element E4 is 7.1 mm, the focal length f5 of the fifth lens element E5 is -4 mm, the focal length f6 of the sixth lens element E6 is 8.8 mm, and the total optical length TTL is 22.68 mm. The surface type, curvature radius, thickness, and material parameters of each lens are shown in Table 3: Table 3: Basic parameters of the optical system of Example 2

[0032] In Table 3 above, OBJ is the object plane; S1 and S2 correspond to the two surfaces of the first lens E1; S3 and S4 correspond to the two surfaces of the second lens E2; S6 and S7 correspond to the two surfaces of the third lens E3; S8 and S9 correspond to the two surfaces of the fourth lens E4; S9 and S10 correspond to the two surfaces of the fifth lens E5; S11 and S12 correspond to the two surfaces of the sixth lens E6; STO is the position of the aperture; S13 and S14 correspond to the two surfaces of the filter E7; and IMA corresponds to the image plane.

[0033] Furthermore, in Table 3, the object side and image side of any one of the second lens 2, the third lens 4, the fifth lens 5, and the sixth lens 6 are aspherical surfaces. The surface shape of each aspherical lens can be defined by, but not limited to, the following aspherical surface formula:

[0034] Where 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 aspheric vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th higher-order term in the aspheric surface shape formula. Table 4 shows the conic coefficients and higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 for various aspheric surfaces that can be used in Example 2.

[0035] Table 4: Aspheric surface related values ​​of the lens surface of Example 2

[0036] Figure 5 The astigmatism and distortion curves of the optical imaging lens of Example 2 are shown. Astigmatism represents meridional image curvature and sagittal image curvature, and distortion represents the distortion magnitude corresponding to different image heights. Figure 6 The MTF curve of the optical imaging lens of Example 2 is shown, which represents the MTF values ​​in the meridian and sagittal directions of different fields of view at different spatial frequencies. Figure 5 and Figure 6 It can be seen that the optical imaging system provided in Example 2 can achieve good imaging quality and has higher imaging quality.

[0037] Specifically, as another preferred embodiment of the present invention but not limiting, Figure 7-9 As shown, in this embodiment 3, the focal length f1 of the first lens element E1 is -5.9 mm, the focal length f2 of the second lens element E2 is 62.5 mm, the focal length f3 of the third lens element E3 is 7.2 mm, the focal length f4 of the fourth lens element E4 is 7.4 mm, the focal length f5 of the fifth lens element E5 is -4.1 mm, the focal length f6 of the sixth lens element E6 is 8.5 mm, and the total optical length TTL is 22.67 mm. The surface type, curvature radius, thickness, and material parameters of each lens are shown in Table 5: Table 5: Basic parameters of the optical system of Example 3

[0038] 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 E1; S3 and S4 correspond to the two surfaces of the second lens E2; S6 and S7 correspond to the two surfaces of the third lens E3; S8 and S9 correspond to the two surfaces of the fourth lens E4; S9 and S10 correspond to the two surfaces of the fifth lens E5; S11 and S12 correspond to the two surfaces of the sixth lens E6; STO is the position of the aperture; S13 and S14 correspond to the two surfaces of the filter E7; and IMA corresponds to the image plane.

[0039] Furthermore, in Table 5, any one of the object side and image side of the second lens E2, the third lens E4, the fifth lens E5, and the sixth lens E6 is aspherical. The surface shape of each aspherical lens can be defined using, but not limited to, the following aspherical surface formula:

[0040] Where 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 aspheric vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th higher-order term in the aspheric surface shape formula. Table 6 shows the conic coefficients and higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 for various aspheric surfaces that can be used in Example 3.

[0041] Table 6: Aspheric surface related values ​​of the lens surface of Example 3

[0042] Figure 8 The astigmatism and distortion curves of the optical imaging lens of Example 3 are shown. Astigmatism represents meridional image curvature and sagittal image curvature, and distortion represents the distortion magnitude corresponding to 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 meridian and sagittal directions of different fields of view at different spatial frequencies. Figure 8 and Figure 9 It can be seen that the optical imaging system provided in Example 3 can achieve good imaging quality and has higher imaging quality.

[0043] Furthermore, in Examples 1-3, the basic data are as follows: Table 7: Basic data of Examples 1-3

[0044] A camera module includes at least an optical lens. The optical system is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens in sequence along the optical axis from the object plane to the image plane. By rationally allocating the surface shape and optical focal length of each lens and optimizing the lens aberration, the module has excellent resolution, high pixel count, large aperture, athermalization, day and night confocality, and light weight, making it more competitive in the IPC market.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A large aperture day and night confocal optical system, comprising, in order from the object plane to the image plane along the optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, characterized in that: The object side of the first lens is convex, the image side is concave, and its optical power is negative; The second lens has a concave object side and a convex image side, and its optical power is positive; The object side and image side of the third lens are convex, and its optical power is positive; The fourth lens has optical power; The fifth lens has optical power; The sixth lens has a convex object side surface and a convex or concave image side surface, and has positive refractive power. Each lens of the optical system meets the following conditions: -7.5mm<f1<-3.5mm; 5mm<f2<100mm; 4.5mm<f3<10.3mm; -7.3mm<f4<9.2mm; -6.5mm<f5<5.2mm; 5.1mm<f6<29mm; Among them, 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, f5 is the focal length of the fifth lens, and f6 is the focal length of the sixth lens.

2. The large aperture day and night confocal optical system according to claim 1, characterized in that: Each lens of the optical system meets the following conditions: Nd1>1.71,Vd1<63; Nd2>1.62,Vd2<30; Nd3>1.55,Vd3<72; Nd4>1.45,Vd4<60; Nd5>1.45,Vd5<60; Nd6>1.45,Vd6<60; Wherein, Nd1 is the refractive index of the first lens element, and Vd1 is the Abbe number of the first lens element; Nd2 is the refractive index of the second lens element, and Vd2 is the Abbe number of the second lens element; Nd3 is the refractive index of the third lens element, and Vd3 is the Abbe number of the third lens element; Nd4 is the refractive index of the fourth lens element, and Vd4 is the Abbe number of the fourth lens element; Nd5 is the refractive index of the fifth lens element, and Vd5 is the Abbe number of the fifth lens element; Nd6 is the refractive index of the sixth lens element, and Vd6 is the Abbe number of the sixth lens element.

3. The large aperture day and night confocal optical system according to claim 1, characterized in that: The relative illumination of the maximum field of view of the optical system meets the following requirements: RI ≥ 45%.

4. The large aperture day and night confocal optical system according to any one of claims 1 to 3, characterized in that: The curvature radius R1 of the object surface side of the first lens satisfies: R1 > 20 mm.

5. The large aperture day and night confocal optical system according to any one of claims 1 to 3, characterized in that: The total optical length TTL of the system meets the following requirements: TTL ≤ 23.5mm.

6. The large aperture day and night confocal optical system according to any one of claims 1 to 3, characterized in that: The third lens is a glass lens.

7. The large aperture day and night confocal optical system according to any one of claims 1 to 3, characterized in that: The horizontal field angle FOV of the optical system satisfies: FOV ≥ 140°, and the maximum image circle satisfies: MIC ≥ 6.9 mm.

8. The large aperture day and night confocal optical system according to any one of claims 1 to 3, characterized in that: The aperture is arranged between the second lens and the third lens.

9. The large aperture day and night confocal optical system according to any one of claims 1 to 3, characterized in that: The fourth lens and the fifth lens are cemented together to form a combined lens.

10. A camera module, comprising at least an optical lens, characterized in that: The optical system according to any one of claims 1 to 9 is installed in the optical lens.

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