A camera system

Abstract

The present invention discloses an imaging system, which sequentially includes, from the object side to the image side along the optical axis: a first lens with a positive optical power, the concave surface on its image side; a second lens with a negative optical power, the concave surface on its object side and the concave surface on its image side; a third lens with a positive optical power; wherein, the f-number Fno of the imaging system satisfies: Fno < 1.3. When the above optical power and surface type conditions are satisfied, it is beneficial to the reasonable spatial distribution of the optical power from the first lens to the third lens, beneficial to reducing the aberration of the lens. At the same time, the large aperture is beneficial to increasing the light passing aperture of the imaging system, allowing more light to enter the image plane, and is beneficial to improving the shooting effect under dark night conditions.

Description

Technical Field

[0001] The present invention belongs to the field of optical imaging, and particularly relates to an imaging system including three lenses. Background Art

[0002] In recent years, consumers have increasingly higher requirements for the shooting functions of mobile phones. Functions such as face recognition and ranging have emerged as the times require. However, due to the complexity of the shooting environment, it is very difficult to obtain clear images in a dim environment. The current mobile phone lenses are limited in imaging in an environment with insufficient light and cannot achieve extremely clear imaging effects. At this time, an infrared lens can well solve this problem. The infrared lens can enhance the light input of the entire imaging system by collecting infrared light in the shooting environment. Compared with the multiple shooting algorithm synthesis of the night scene mode of the previous mobile phone lenses, the image resolution obtained by the infrared lens will not decrease, which is another simpler and more effective solution; and since this function is required for mobile phones of different price ranges, a low-cost solution that meets the performance requirements is more competitive.

[0003] Therefore, the present solution provides an optical imaging lens group with the characteristics of infrared, large aperture, and low cost, which can effectively improve the imaging quality, meet the shooting requirements in a dim environment, and better control the cost. Summary of the Invention

[0004] The present invention aims to provide a small-sized imaging system with high imaging quality and a small system volume, having the characteristics of infrared, large aperture, and low cost, and can effectively improve the imaging quality, etc.

[0005] The present application provides an imaging system, which sequentially includes, from the object side to the image side along the optical axis:

[0006] A first lens with positive optical power, having a concave surface on its image side;

[0007] A second lens with negative optical power, having a concave surface on its object side and a concave surface on its image side;

[0008] A third lens with positive optical power;

[0009] Wherein, the f-number Fno of the imaging system satisfies: Fno < 1.3.

[0010] According to an embodiment of the present application, the effective focal length f of the imaging system and half of the maximum field of view angle semi-fov of the imaging system satisfy: 1.1 mm < f × tan(semi-fov).

[0011] According to an embodiment of the present application, the effective semi-aperture DT12 of the image side of the first lens and half of the diagonal length ImgH of the effective pixel area on the imaging surface satisfy: 0.4 < DT12 / ImgH < 0.6.

[0012] According to an embodiment of the present application, the combined focal length f23 of the second lens and the third lens and the effective focal length f of the imaging system satisfy: 1 < f23 / f < 1.5.

[0013] According to an embodiment of the present application, the effective focal length f1 of the first lens and the effective focal length f of the imaging system satisfy: 2 < f1 / f < 3.

[0014] According to an embodiment of the present application, the entrance pupil diameter EPD of the imaging system and the effective focal length f3 of the third lens satisfy: 1.2 < EPD / f3 < 1.8.

[0015] According to an embodiment of the present application, the edge thickness ET2 of the second lens and the central thickness CT2 of the second lens on the optical axis satisfy: 0.6 < ET2 / CT2 < 0.7.

[0016] According to an embodiment of the present application, the distance TD on the optical axis from the object side surface of the first lens to the image side surface of the third lens in the imaging system and the distance BFL on the optical axis from the image side surface of the third lens to the imaging surface in the imaging system satisfy: TD / BFL < 1.4.

[0017] According to an embodiment of the present application, the central thickness CT1 of the first lens on the optical axis, the central thickness CT3 of the third lens on the optical axis, and the air gap distance T23 on the optical axis between the second lens and the third lens satisfy: 11 < (CT1 + CT3) / T23 < 17.

[0018] According to an embodiment of the present application, the radius of curvature R3 of the object side surface of the second lens and the radius of curvature R4 of the image side surface of the second lens satisfy: R3 / R4 < -7.1.

[0019] The present application also provides an imaging system, which sequentially includes, from the object side to the image side along the optical axis:

[0020] A first lens with positive optical power, whose object side surface is convex and image side surface is concave;

[0021] A second lens with negative optical power, whose object side surface is concave and image side surface is concave;

[0022] A third lens with positive optical power;

[0023] Wherein, the f-number Fno of the imaging system satisfies: Fno < 1.3.

[0024] According to an embodiment of the present application, the effective focal length f of the imaging system and half of the maximum field of view semi-fov of the imaging system satisfy: 1.1 mm < f × tan(semi-fov).

[0025] According to an embodiment of the present application, the effective semi-aperture DT12 of the image side of the first lens and half of the diagonal length ImgH of the effective pixel region on the imaging surface satisfy: 0.4 < DT12 / ImgH < 0.6.

[0026] According to an embodiment of the present application, the combined focal length f23 of the second lens and the third lens and the effective focal length f of the imaging system satisfy: 1 < f23 / f < 1.5.

[0027] According to an embodiment of the present application, the effective focal length f1 of the first lens and the effective focal length f of the imaging system satisfy: 2 < f1 / f < 3.

[0028] According to an embodiment of the present application, the entrance pupil diameter EPD of the imaging system and the effective focal length f3 of the third lens satisfy: 1.2 < EPD / f3 < 1.8.

[0029] According to an embodiment of the present application, the edge thickness ET2 of the second lens and the central thickness CT2 of the second lens on the optical axis satisfy: 0.6 < ET2 / CT2 < 0.7.

[0030] According to an embodiment of the present application, the distance TD on the optical axis from the object side of the first lens to the image side of the third lens in the imaging system and the distance BFL on the optical axis from the image side of the third lens to the imaging surface in the imaging system satisfy: TD / BFL < 1.4.

[0031] According to an embodiment of the present application, the central thickness CT1 of the first lens on the optical axis, the central thickness CT3 of the third lens on the optical axis, and the air spacing distance T23 of the second lens and the third lens on the optical axis satisfy: 11 < (CT1 + CT3) / T23 < 17.

[0032] According to an embodiment of the present application, the radius of curvature R3 of the object side of the second lens and the radius of curvature R4 of the image side of the second lens satisfy: R3 / R4 < -7.1.

[0033] Advantages of the present invention:

[0034] The imaging system provided by the present invention includes multiple lenses, such as the first lens to the third lens. When the above-mentioned optical power and surface type conditions are satisfied, it is beneficial to the reasonable spatial distribution of the optical power from the first lens to the third lens, which is beneficial to reducing the aberration of the lens. At the same time, the large aperture is beneficial to increasing the light passing aperture of the imaging system, allowing more light to enter the image plane, which is beneficial to improving the shooting effect under dark night conditions. Description of the Drawings

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 Schematic diagram of the lens group structure of Embodiment 1 of the camera system of the present invention;

[0037] Figures 2a to 2c Respectively, the distortion curve, the axial chromatic aberration curve, and the astigmatism curve of Embodiment 1 of the camera system of the present invention;

[0038] Figure 3 Schematic diagram of the lens group structure of Embodiment 2 of the camera system of the present invention;

[0039] Figures 4a to 4c Respectively, the distortion curve, the axial chromatic aberration curve, and the astigmatism curve of Embodiment 2 of the camera system of the present invention;

[0040] Figure 5 Schematic diagram of the lens group structure of Embodiment 3 of the camera system of the present invention;

[0041] Figures 6a to 6c Respectively, the distortion curve, the axial chromatic aberration curve, and the astigmatism curve of Embodiment 3 of the camera system of the present invention;

[0042] Figure 7 Schematic diagram of the lens group structure of Embodiment 4 of the camera system of the present invention;

[0043] Figures 8a to 8c Respectively, the distortion curve, the axial chromatic aberration curve, and the astigmatism curve of Embodiment 4 of the camera system of the present invention. Detailed implementation manners

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0045] It should be noted that in this specification, the expressions such as first, second, and third are only used to distinguish one feature from another feature, and do not represent any limitation on the feature. Therefore, without departing from the teachings of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0046] It should also be understood that the terms "comprises", "comprising", "has", "including" and / or "including" when used in this specification denote the presence of the stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. Further, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features rather than individual elements in the list. Further, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the term "exemplary" is intended to refer to an example or illustration.

[0047] In the drawings, for ease of illustration, the thickness, dimensions and shape of the lens have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are for illustrative purposes only and are not drawn to an exact scale.

[0048] In the description of the present invention, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region. If the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object being photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0049] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0050] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other. The features, principles and other aspects of the present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0051] Exemplary Embodiments

[0052] The imaging system according to an exemplary embodiment of the present invention includes three lenses, which are sequentially arranged from the object side to the image side along the optical axis: a first lens, a second lens, and a third lens, wherein each lens is independent of each other.

[0053] In the present exemplary embodiment, along the optical axis from the object side to the image side, it sequentially includes: a first lens with a positive optical power, having a concave surface on the image side; a second lens with a negative optical power, having a concave surface on the object side and a concave surface on the image side; a third lens with a positive optical power. When the above-mentioned optical power and surface shape conditions are satisfied, it is beneficial to the reasonable spatial distribution of the optical power from the first lens to the third lens, beneficial to reducing the aberration of the lens. At the same time, the large aperture is beneficial to increasing the light passing aperture of the imaging system, allowing more light to enter the image plane, and is beneficial to improving the shooting effect under dark night conditions.

[0054] More specifically, along the optical axis from the object side to the image side, it sequentially includes: a first lens with a positive optical power, having a convex surface on the object side and a concave surface on the image side; a second lens with a negative optical power, having a concave surface on the object side and a concave surface on the image side; a third lens with a positive optical power. When the above-mentioned optical power and surface shape conditions are satisfied, it is beneficial to the reasonable spatial distribution of the optical power from the first lens to the third lens, beneficial to reducing the aberration of the lens. At the same time, the large aperture is beneficial to increasing the light passing aperture of the imaging system, allowing more light to enter the image plane, and is beneficial to improving the shooting effect under dark night conditions.

[0055] In the present exemplary embodiment, the effective focal length f of the imaging system and half of the maximum field of view angle semi - fov of the imaging system satisfy: 1.1mm < f × tan(semi - fov). This meets the large field of view angle; the large field of view angle is beneficial to broadening the shooting view range. More specifically, the effective focal length f of the imaging system and half of the maximum field of view angle semi - fov of the imaging system satisfy: 1.15mm < f × tan(semi - fov).

[0056] In the present exemplary embodiment, the effective semi - aperture DT12 of the image side surface of the first lens and half of the diagonal length ImgH of the effective pixel region on the imaging plane satisfy: 0.4 < DT12 / ImgH < 0.6. By controlling the effective semi - aperture of the image side surface of the first lens, it is beneficial to reducing the structural step difference and beneficial to the stability of lens assembly. More specifically, the effective semi - aperture DT12 of the image side surface of the first lens and half of the diagonal length ImgH of the effective pixel region on the imaging plane satisfy: 0.45 < DT12 / ImgH < 0.55.

[0057] In the present exemplary embodiment, the combined focal length f23 of the second lens and the third lens and the effective focal length f of the imaging system satisfy: 1 < f23 / f < 1.5. By controlling the effective focal length of the lens and the combined focal length of the second lens and the third lens, it is beneficial to the distribution of optical power and improves the imaging quality. More specifically, the combined focal length f23 of the second lens and the third lens and the effective focal length f of the imaging system satisfy: 1.10 < f23 / f < 1.45.

[0058] In this exemplary embodiment, the effective focal length f1 of the first lens and the effective focal length f of the imaging system satisfy: 2 < f1 / f < 3. By controlling the effective focal length of the lens, the effective focal length of the first lens is beneficial to the distribution of the optical power and improves the imaging quality. More specifically, the effective focal length f1 of the first lens and the effective focal length f of the imaging system satisfy: 2.05 < f1 / f < 2.95.

[0059] In this exemplary embodiment, the entrance pupil diameter EPD of the imaging system and the effective focal length f3 of the third lens satisfy: 1.2 < EPD / f3 < 1.8. By controlling the entrance pupil diameter and the effective focal length of the third lens, it is beneficial to increase the light passing aperture of the imaging system, allow more light to enter the image plane, and is beneficial to improving the shooting effect under dark night conditions. More specifically, the entrance pupil diameter EPD of the imaging system and the effective focal length f3 of the third lens satisfy: 1.30 < EPD / f3 < 1.70.

[0060] In this exemplary embodiment, the edge thickness ET2 of the second lens and the central thickness CT2 of the second lens on the optical axis satisfy: 0.6 < ET2 / CT2 < 0.7. By controlling the central thickness and the edge thickness of the second lens, it is beneficial to control the shape of the second lens and reduce the lens processing difficulty. More specifically, the edge thickness ET2 of the second lens and the central thickness CT2 of the second lens on the optical axis satisfy: 0.61 ≤ ET2 / CT2 ≤ 0.69.

[0061] In this exemplary embodiment, the distance TD on the optical axis from the object side surface of the first lens to the image side surface of the third lens in the imaging system and the distance BFL on the optical axis from the image side surface of the third lens to the imaging plane in the imaging system satisfy: TD / BFL < 1.4. By controlling the distance on the optical axis from the object side surface of the first lens to the image side surface of the third lens and the distance on the optical axis from the image side surface of the third lens to the imaging plane, the system processability can be ensured and the manufacturing cost can be reduced. More specifically, the distance TD on the optical axis from the object side surface of the first lens to the image side surface of the third lens in the imaging system and the distance BFL on the optical axis from the image side surface of the third lens to the imaging plane in the imaging system satisfy: TD / BFL < 1.39.

[0062] In this exemplary embodiment, the central thickness CT1 of the first lens on the optical axis, the central thickness CT3 of the third lens on the optical axis, and the air gap distance T23 between the second lens and the third lens on the optical axis satisfy: 11 < (CT1 + CT3) / T23 < 17. By controlling the central thickness of the first lens, the central thickness of the third lens, and the air gap distance between the second and third lenses, it is beneficial to the processability of the first lens and the third lens, as well as the assembly stability, and reduces the processing and assembly difficulties. More specifically, the central thickness CT1 of the first lens on the optical axis, the central thickness CT3 of the third lens on the optical axis, and the air gap distance T23 between the second lens and the third lens on the optical axis satisfy: 11.50 < (CT1 + CT3) / T23 < 16.80.

[0063] In this exemplary embodiment, the radius of curvature R3 of the object side surface of the second lens and the radius of curvature R4 of the image side surface of the second lens satisfy: R3 / R4 < -7.1. By controlling the radius of curvature of the object side surface and the image side surface of the second lens, it is beneficial to control the shape of the second lens and meet the processability requirements. More specifically, the radius of curvature R3 of the object side surface of the second lens and the radius of curvature R4 of the image side surface of the second lens satisfy: R3 / R4 < -7.20.

[0064] In this exemplary embodiment, the object side surface and the image side surface of any one of the first lens E1 to the third lens E3 are aspherical surfaces, and the surface profile x of each aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0065]

[0066] where x is the sagitta of the distance from the vertex of the aspherical surface when the aspherical surface is along the optical axis at a position with a height of h; c is the paraxial curvature of the aspherical surface, c = 1 / R (that is, the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1); k is the conic coefficient; and Ai is the correction coefficient of the i-th order of the aspherical surface.

[0067] In this exemplary embodiment, the above imaging system may further include a diaphragm. The diaphragm can be set at an appropriate position as needed. For example, the diaphragm can be set between the object side and the first lens. Optionally, the above imaging system may further include a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface.

[0068] The imaging system according to the above embodiment of the present invention can adopt multiple lenses, such as the three lenses described above. By reasonably distributing the optical power, surface profile, central thickness of each lens, and the axial spacing between each lens, etc., the imaging system has a large imaging image plane, has the characteristics of a wide imaging range and high imaging quality, and ensures the miniaturization of the volume of the imaging system.

[0069] In an exemplary embodiment, at least one of the mirror surfaces of each lens is an aspherical mirror surface, that is, at least one of the mirror surfaces from the object side surface of the first lens to the image side surface of the third lens is an aspherical mirror surface. The characteristic of an aspherical lens is that the curvature continuously changes from the center of the lens to the periphery of the lens. Different from a spherical lens with a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has better curvature radius characteristics and has the advantages of improving distortion aberration and astigmatism aberration. After using an aspherical lens, it is possible to eliminate as much as possible the aberration that appears during imaging, thereby improving the imaging quality. Optionally, at least one of the object side surface and the image side surface of each of the first lens, the second lens, and the third lens is an aspherical mirror surface. Optionally, both the object side surface and the image side surface of each of the first lens, the second lens, and the third lens are aspherical mirror surfaces.

[0070] However, those skilled in the art should understand that without departing from the technical solutions claimed in the present application, the number of lenses constituting the imaging system can be changed to obtain the various results and advantages described in this specification. For example, although three lenses are described as an example in the embodiment, the imaging system is not limited to including three lenses. If necessary, the imaging system may also include other numbers of lenses.

[0071] The following further describes specific embodiments of the imaging system applicable to the above embodiments with reference to the accompanying drawings. Specific Embodiment 1

[0073] Figure 1 FIG. is a schematic structural diagram of a lens group of Embodiment 1 of the imaging system of the present invention. The imaging system sequentially includes, along the optical axis from the object side to the image side: a stop STO, a first lens E1, a second lens E2, a third lens E3, a filter E4, and an imaging surface S9.

[0074] The first lens E1 has a positive optical power. Its object side surface S1 is a convex surface, and its image side surface S2 is a concave surface. The second lens E2 has a negative optical power. Its object side surface S3 is a concave surface, and its image side surface S4 is a concave surface. The third lens E3 has a positive optical power. Its object side surface S5 is a convex surface, and its image side surface S6 is a concave surface. The filter E4 has an object side surface S7 and an image side surface S8. The light from the object sequentially passes through the surfaces S1 to S8 and finally forms an image on the imaging surface S9.

[0075] As shown in Table 1, it is a basic parameter table of the imaging system of Embodiment 1, where the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0076]

[0077] Table 1

[0078] As shown in Table 2, in Embodiment 1, the total effective focal length f of the imaging system is 1.33 mm, and half of the maximum field of view angle of the optical imaging lens, Semi-FOV = 42.4°. The aperture value Fno of the optical imaging system is 1.20.

[0079]

[0080] Table 2

[0081] The imaging system in Embodiment 1 satisfies:

[0082] f×tan(semi-fov) = 1.22 mm; where f is the effective focal length of the imaging system, and semi-fov is half of the maximum field of view angle of the imaging system.

[0083] DT12 / ImgH = 0.49; where DT12 is the effective semi-aperture of the image side of the first lens, and Imgh is half of the diagonal length of the effective pixel region on the imaging surface.

[0084] f23 / f = 1.28; where f23 is the combined focal length of the second lens and the third lens, and f is the effective focal length of the imaging system.

[0085] f1 / f = 2.56; where f1 is the effective focal length of the first lens, and f is the effective focal length of the imaging system.

[0086] EPD / f3 = 1.38; where EPD is the entrance pupil diameter of the imaging system, and f3 is the effective focal length of the third lens.

[0087] ET2 / CT2 = 0.63; where ET2 is the edge thickness of the second lens, and CT2 is the central thickness of the second lens on the optical axis.

[0088] TD / BFL = 1.21; where TD is the distance on the optical axis from the object side of the first lens to the image side of the third lens in the imaging system, and BFL is the distance on the optical axis from the image side of the third lens to the imaging surface in the imaging system.

[0089] (CT1 + CT3) / T23 = 11.75; where CT1 is the central thickness of the first lens on the optical axis, CT3 is the central thickness of the third lens on the optical axis, and T23 is the air interval distance between the second lens and the third lens on the optical axis.

[0090] R3 / R4 = -8.50; where R3 is the curvature radius of the object side of the second lens, and R4 is the curvature radius of the image side of the second lens.

[0091] In Embodiment 1, the object side and the image side of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 3 shows the higher-order term coefficients A4, A6, a8, a 10 , A 12 , A 14 , A 16 , A 18 , A 20 , A 22 , A 24 , A 26 , A 28 and A 30 .

[0092]

[0093]

[0094] Table 3

[0095] Figure 2a shows the distortion curve of the imaging system of Embodiment 1, which represents the distortion magnitude values corresponding to different image heights. Figure 2b shows the axial chromatic aberration curve of the imaging system of Embodiment 1, which represents the deviation of the convergence points of light rays of different wavelengths after passing through the lens. Figure 2c shows the astigmatism curve of the imaging system of Embodiment 1, which represents the meridional image plane curvature and the sagittal image plane curvature. According to Figures 2a to 2c shown, the imaging system given in Embodiment 1 can achieve good imaging quality. Specific Embodiment 2

[0097] Figure 3 is a schematic structural diagram of the lens group of Embodiment 2 of the imaging system of the present invention. The imaging system sequentially includes, along the optical axis from the object side to the image side: a stop STO, a first lens E1, a second lens E2, a third lens E3, a filter E4, and an imaging surface S9.

[0098] The first lens E1 has a positive optical power. Its object side S1 is a convex surface, and its image side S2 is a concave surface. The second lens E2 has a negative optical power. Its object side S3 is a concave surface, and its image side S4 is a concave surface. The third lens E3 has a positive optical power. Its object side S5 is a convex surface, and its image side S6 is a concave surface. The filter E4 has an object side S7 and an image side S8. Light from the object sequentially passes through the surfaces S1 to S8 and finally forms an image on the imaging surface S9.

[0099] As shown in Table 4, it is the basic parameter table of the imaging system of Embodiment 2, where the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0100]

[0101] Table 4

[0102] As shown in Table 5, in Embodiment 2, the total effective focal length f of the imaging system is 1.48 mm, and half of the maximum field of view angle of the optical imaging lens, Semi-FOV = 38.4°. The aperture value Fno of the optical imaging system is 1.20.

[0103]

[0104] Table 5

[0105] The imaging system in Embodiment 2 satisfies:

[0106] f × tan(semi-fov) = 1.17 mm; where f is the effective focal length of the imaging system, and semi-fov is half of the maximum field of view angle of the imaging system.

[0107] DT12 / ImgH = 0.53; where DT12 is the effective semi-aperture of the image side of the first lens, and Imgh is half of the diagonal length of the effective pixel area on the imaging surface.

[0108] f23 / f = 1.42; where f23 is the combined focal length of the second lens and the third lens, and f is the effective focal length of the imaging system.

[0109] f1 / f = 2.06; where f1 is the effective focal length of the first lens, and f is the effective focal length of the imaging system.

[0110] EPD / f3 = 1.67; where EPD is the entrance pupil diameter of the imaging system, and f3 is the effective focal length of the third lens.

[0111] ET2 / CT2 = 0.69; where ET2 is the edge thickness of the second lens, and CT2 is the central thickness of the second lens on the optical axis.

[0112] TD / BFL = 1.36; where TD is the distance on the optical axis from the object side of the first lens to the image side of the third lens in the imaging system, and BFL is the distance on the optical axis from the image side of the third lens to the imaging surface in the imaging system.

[0113] (CT1 + CT3) / T23 = 16.60; where CT1 is the central thickness of the first lens on the optical axis, CT3 is the central thickness of the third lens on the optical axis, and T23 is the air spacing distance on the optical axis between the second lens and the third lens.

[0114] R3 / R4 = -8.71; where R3 is the curvature radius of the object side of the second lens, and R4 is the curvature radius of the image side of the second lens.

[0115] In Embodiment 2, the object side and the image side of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 6 shows the higher-order term coefficients A4, A6, A8, A 10 , A 12 , A 14 ), 16 ), 18 , A 20 , A 22 , A 24 , A 26 , A 28 and A 30 .

[0116]

[0117]

[0118] Table 6

[0119] Figure 4a shows the distortion curve of the imaging system of Embodiment 2, which represents the distortion magnitude values corresponding to different image heights. Figure 4b shows the axial chromatic aberration curve of the imaging system of Embodiment 2, which represents the deviation of the convergence points of light rays of different wavelengths after passing through the lens. Figure 4c shows the astigmatism curve of the imaging system of Embodiment 2, which represents the meridional image plane curvature and the sagittal image plane curvature. According to Figures 4a to 4c shown, the imaging system given in Embodiment 2 can achieve good imaging quality. Specific Embodiment 3

[0121] Figure 5 This is a schematic structural diagram of the lens group of Embodiment 3 of the imaging system of the present invention. The imaging system sequentially includes, from the object side to the image side along the optical axis: a stop STO, a first lens E1, a second lens E2, a third lens E3, a filter E4, and an imaging surface S9.

[0122] The first lens E1 has a positive optical power. Its object side S1 is a convex surface, and its image side S2 is a concave surface. The second lens E2 has a negative optical power. Its object side S3 is a concave surface, and its image side S4 is a concave surface. The third lens E3 has a positive optical power. Its object side S5 is a convex surface, and its image side S6 is a concave surface. The filter E4 has an object side S7 and an image side S8. Light from the object sequentially passes through the surfaces S1 to S8 and finally forms an image on the imaging surface S9.

[0123] As shown in Table 7, it is the basic parameter table of the imaging system of Embodiment 3, where the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0124]

[0125] Table 7

[0126] As shown in Table 8, in Embodiment 3, the total effective focal length f of the imaging system is 1.38 mm, and half of the maximum field of view angle of the optical imaging lens, Semi-FOV = 40.8°. The aperture value Fno of the optical imaging system is 1.20.

[0127]

[0128]

[0129] Table 8

[0130] The imaging system in Embodiment 3 satisfies:

[0131] f × tan(semi-fov) = 1.20 mm; where f is the effective focal length of the imaging system, and semi-fov is half of the maximum field of view angle of the imaging system.

[0132] DT12 / ImgH = 0.51; where DT12 is the effective semi-aperture of the image side of the first lens, and Imgh is half of the diagonal length of the effective pixel region on the imaging surface.

[0133] f23 / f = 1.32; where f23 is the combined focal length of the second lens and the third lens, and f is the effective focal length of the imaging system.

[0134] f1 / f = 2.32; where f1 is the effective focal length of the first lens, and f is the effective focal length of the imaging system.

[0135] EPD / f3 = 1.51; where EPD is the entrance pupil diameter of the imaging system, and f3 is the effective focal length of the third lens.

[0136] ET2 / CT2 = 0.67; where ET2 is the edge thickness of the second lens, and CT2 is the central thickness of the second lens on the optical axis.

[0137] TD / BFL = 1.26; where TD is the distance on the optical axis from the object side of the first lens to the image side of the third lens in the imaging system, and BFL is the distance on the optical axis from the image side of the third lens to the imaging surface in the imaging system.

[0138] (CT1 + CT3) / T23 = 13.56; where CT1 is the central thickness of the first lens on the optical axis, CT3 is the central thickness of the third lens on the optical axis, and T23 is the air separation distance on the optical axis between the second lens and the third lens.

[0139] R3 / R4 = -9.14; where R3 is the curvature radius of the object side of the second lens, and R4 is the curvature radius of the image side of the second lens.

[0140] In Embodiment 3, the object side and the image side of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 9 shows the higher-order term coefficients A4, A6, a8, a 10 , A 12 , A 14 , A 16 , A 18 , A 20 , A 22 , A 24 , A 26 , A 28 and A 30 .

[0141]

[0142]

[0143] Table 9

[0144] Figure 6a shows the distortion curve of the imaging system of Embodiment 3, which represents the distortion magnitude values corresponding to different image heights. Figure 6b shows the axial chromatic aberration curve of the imaging system of Embodiment 3, which represents the deviation of the convergence points of light rays of different wavelengths after passing through the lens. Figure 6c shows the astigmatism curve of the imaging system of Embodiment 3, which represents the meridional image plane curvature and the sagittal image plane curvature. According to Figures 6a to 6c shown, the imaging system given in Embodiment 3 can achieve good imaging quality. Specific Embodiment 4

[0146] Figure 7 is a schematic structural diagram of the lens group of Embodiment 4 of the imaging system of the present invention. The imaging system sequentially includes, from the object side to the image side along the optical axis: a diaphragm STO, a first lens E1, a second lens E2, a third lens E3, a filter E4, and an imaging surface S9.

[0147] The first lens E1 has a positive optical power. Its object side S1 is a convex surface, and its image side S2 is a concave surface. The second lens E2 has a negative optical power. Its object side S3 is a concave surface, and its image side S4 is a concave surface. The third lens E3 has a positive optical power. Its object side S5 is a convex surface, and its image side S6 is a concave surface. The filter E4 has an object side S7 and an image side S8. Light from the object sequentially passes through the surfaces S1 to S8 and finally forms an image on the imaging surface S9.

[0148] As shown in Table 10, it is the basic parameter table of the imaging system in Embodiment 4, where the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0149]

[0150] Table 10

[0151] As shown in Table 11, in Embodiment 4, the total effective focal length f of the imaging system is 1.28 mm, and half of the maximum field of view angle of the optical imaging lens, Semi - FOV = 43.8°. The aperture value Fno of the optical imaging system is 1.20.

[0152]

[0153]

[0154] Table 11

[0155] The imaging system in Embodiment 4 satisfies:[[]]

[0156] f×tan(semi - fov)=1.23 mm; where f is the effective focal length of the imaging system, and semi - fov is half of the maximum field of view angle of the imaging system.

[0157] DT12 / ImgH = 0.48; where DT12 is the effective semi - aperture of the image side of the first lens, and Imgh is half of the diagonal length of the effective pixel area on the imaging surface.

[0158] f23 / f = 1.21; where f23 is the combined focal length of the second lens and the third lens, and f is the effective focal length of the imaging system.

[0159] f1 / f = 2.92; where f1 is the effective focal length of the first lens, and f is the effective focal length of the imaging system.

[0160] EPD / f3 = 1.39; where EPD is the entrance pupil diameter of the imaging system, and f3 is the effective focal length of the third lens.

[0161] ET2 / CT2 = 0.61; where ET2 is the edge thickness of the second lens, and CT2 is the central thickness of the second lens on the optical axis.

[0162] TD / BFL = 1.16; where TD is the distance on the optical axis from the object side of the first lens to the image side of the third lens in the imaging system, and BFL is the distance on the optical axis from the image side of the third lens to the imaging surface in the imaging system.

[0163] (CT1 + CT3) / T23 = 13.32; where CT1 is the central thickness of the first lens on the optical axis, CT3 is the central thickness of the third lens on the optical axis, and T23 is the air separation distance between the second lens and the third lens on the optical axis.

[0164] R3 / R4 = -7.28; where R3 is the curvature radius of the object side surface of the second lens, and R4 is the curvature radius of the image side surface of the second lens.

[0165] In Embodiment 4, the object side surface and the image side surface of any one of the first lens E1 to the third lens E3 are aspherical surfaces. Table 12 shows the higher-order term coefficients A4, A6, A8, A 10 、) 12 、A 14 、A 16 、A 18 、A 20 、A 22 、A 24 、A 26 、A 28 and A 30 .

[0166] Face number A4 A6 A8 A10 A12 A14 A16 S1 1.0180E+00 -7.7641E+01 4.4430E+03 -1.7189E+05 4.1509E+06 -6.4823E+07 6.8276E+08 S2 -1.3136E+00 7.6447E+00 2.2425E+03 -1.0443E+05 2.3327E+06 -3.1794E+07 2.8764E+08 S3 -2.2707E+00 7.3520E+01 -2.0516E+03 4.6948E+04 -7.9254E+05 9.3345E+06 -7.6420E+07 S4 -9.3665E+00 -1.7399E+02 1.0046E+04 -2.3866E+05 3.5316E+06 -3.5548E+07 2.5246E+08 S5 -7.6758E+00 6.1167E+01 -3.8555E+02 3.4417E+03 -5.5248E+04 6.3271E+05 -4.5053E+06 S6 4.8691E+00 -8.2215E+01 1.2686E+03 -1.5363E+04 1.2662E+05 -7.1230E+05 2.8015E+06 Face number A18 A20 A22 A24 A26 A28 A30 S1 -4.9891E+09 2.5623E+10 -9.2268E+10 2.2821E+11 -3.6933E+11 3.5223E+11 -1.5007E+11 S2 -1.7962E+09 7.8668E+09 -2.4120E+10 5.0702E+10 -6.9592E+10 5.6145E+10 -2.0174E+10 S3 4.3898E+08 -1.7791E+09 5.0615E+09 -9.8972E+09 1.2676E+10 -9.5801E+09 3.2410E+09 S4 -1.2860E+09 4.7136E+09 -1.2312E+10 2.2333E+10 -2.6696E+10 1.8884E+10 -5.9793E+09 S5 2.0964E+07 -6.6056E+07 1.4252E+08 -2.0788E+08 1.9626E+08 -1.0835E+08 2.6579E+07 S6 -7.8360E+06 1.5679E+07 -2.2286E+07 2.1978E+07 -1.4300E+07 5.5213E+06 -9.5842E+05

[0167] Table 12

[0168] Figure 8a shows the distortion curve of the imaging system of Embodiment 4, which represents the distortion magnitude values corresponding to different image heights. Figure 8b shows the axial chromatic aberration curve of the imaging system of Embodiment 4, which represents the deviation of the focusing points of light rays of different wavelengths after passing through the lens. Figure 8c shows the astigmatism curve of the imaging system of Embodiment 4, which represents the meridional image plane curvature and the sagittal image plane curvature. According to Figures 8a to 8c as shown, the imaging system given in Embodiment 4 can achieve good imaging quality.

[0169] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, improvements, equivalent replacements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A camera system, characterized in that, The number of lenses with optical power in the imaging system is three. The imaging system sequentially includes, from the object side to the image side along the optical axis: A first lens with positive optical power, having a convex surface on the object side and a concave surface on the image side; A second lens with negative optical power, having a concave surface on the object side and a concave surface on the image side; A third lens with positive optical power, having a convex surface on the object side and a concave surface on the image side; Among them, the f-number Fno of the imaging system satisfies: Fno = 1.2; The entrance pupil diameter EPD of the imaging system and the effective focal length f3 of the third lens satisfy: 1.38 ≤ EPD / f3 ≤ 1.

67.

2. The imaging system according to claim 1, wherein The effective focal length f of the imaging system and half of the maximum field of view angle semi-fov of the imaging system satisfy: 1.17 mm ≤ f × tan(semi-fov) ≤ 1.23 mm.

3. The imaging system according to claim 1, characterized in that The effective semi-aperture DT12 of the image side surface of the first lens and half ImgH of the diagonal length of the effective pixel region on the imaging surface satisfy: 0.48 ≤ DT12 / ImgH ≤ 0.

53.

4. The imaging system according to claim 1, wherein The combined focal length f23 of the second lens and the third lens and the effective focal length f of the imaging system satisfy: 1.21 ≤ f23 / f ≤ 1.

42.

5. The imaging system according to claim 1, wherein The effective focal length f1 of the first lens and the effective focal length f of the imaging system satisfy: 2.06 ≤ f1 / f ≤ 2.

92.

6. The imaging system according to claim 1, characterized in that The edge thickness ET2 of the second lens and the central thickness CT2 of the second lens on the optical axis satisfy: 0.6 < ET2 / CT2 < 0.

7.

7. The imaging system according to claim 1, characterized in that, The distance TD on the optical axis from the object side surface of the first lens to the image side surface of the third lens in the imaging system and the distance BFL on the optical axis from the image side surface of the third lens to the imaging surface in the imaging system satisfy: 1.16 ≤ TD / BFL < 1.

4.

8. The imaging system according to claim 1, wherein The central thickness CT1 of the first lens on the optical axis, the central thickness CT3 of the third lens on the optical axis, and the air separation distance T23 between the second lens and the third lens on the optical axis satisfy: 11.75 ≤ (CT1 + CT3) / T23 ≤ 16.

6.

9. The imaging system according to claim 1, wherein The curvature radius R3 of the object side surface of the second lens and the curvature radius R4 of the image side surface of the second lens satisfy: -9.14 ≤ R3 / R4 ≤ -7.28.

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