Optical System, Camera Module, and Electronic Device

Abstract

An optical system, a camera module, and an electronic device. The optical system sequentially includes, from the object side to the image side: a first lens having a positive refractive power, with the object side being convex near the optical axis; a second lens having a refractive power; a third lens having a refractive power, with the image side being concave near the optical axis; a fourth lens having a negative refractive power, with the object side being convex near the optical axis and the image side being concave near the optical axis; a fifth lens having a refractive power, with the object side being concave near the optical axis; a sixth lens having a refractive power, with the image side being convex near the optical axis; a seventh lens having a negative refractive power, with the image side being concave near the optical axis, and both the object side and the image side being aspherical, and at least one of them is provided with at least one inflection point. By reasonably configuring the refractive powers and surface shapes of the first lens to the seventh lens and setting the inflection point, the optical system can balance the effective focal length and the overall length of the system, thereby having a sufficiently long effective focal length and a short overall length of the system.

Description

Technical Field

[0001] The present invention belongs to the field of optical imaging, and particularly relates to an optical system, a camera module, and an electronic device. Background Art

[0002] With the continuous development of the manufacturing technology of various photographing devices such as mobile phones and cameras, in order to meet the photographing needs of the majority of users, their cameras are also developing rapidly synchronously. For example, in recent years, there have been cameras that simultaneously carry multiple cameras with different functions to meet the shooting requirements of various scenarios, such as simultaneously carrying a wide-angle camera and a telephoto camera.

[0003] Currently, the trend of the development of photographing devices is towards miniaturization, making it difficult for the telephoto cameras on them to balance the effective focal length and the total system length. Either the effective focal length is too short to perform telephoto shooting, or the total system length is too long to be adapted to small photographing devices such as mobile phones. Summary of the Invention

[0004] The purpose of the present invention is to provide an optical system, a camera module, and an electronic device that can balance the effective focal length and the total system length, so as to have a sufficiently long effective focal length and a short total system length, and can simultaneously meet the requirements of miniaturization and telephoto imaging.

[0005] To achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides an optical system. The optical system sequentially includes, from the object side to the image side: a first lens having a positive refractive power, and the object side surface of the first lens is convex near the optical axis; a second lens having a refractive power; a third lens having a refractive power, and the image side surface of the third lens is concave near the optical axis; a fourth lens having a negative refractive power, the object side surface of the fourth lens is convex near the optical axis, and the image side surface of the fourth lens is concave near the optical axis; a fifth lens having a refractive power, the object side surface of the fifth lens is concave near the optical axis; a sixth lens having a refractive power, the image side surface of the sixth lens is convex near the optical axis; a seventh lens having a negative refractive power, the image side surface of the seventh lens is concave near the optical axis, both the object side surface and the image side surface of the seventh lens are aspherical surfaces, and at least one of the object side surface and the image side surface of the seventh lens is provided with at least one inflection point.

[0007] By reasonably configuring the refractive powers and surface types of the first lens to the seventh lens, and setting an inflection point on the seventh lens, the optical system can balance the effective focal length and the total system length, so as to have a sufficiently long effective focal length and a short total system length, and can simultaneously meet the requirements of miniaturization and telephoto imaging.

[0008] In one embodiment, the optical system satisfies the conditional formula: f / TTL > 1; where f is the effective focal length of the optical system, and TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis. By satisfying that the value of f / TTL is higher than 1, the effective focal length of the optical system is longer, thus having a telephoto characteristic.

[0009] In one embodiment, the optical system satisfies the conditional formula: 0mm -1 <FNO / (ImgH*2)<5mm -1 ; where FNO is the aperture number of the optical system, and Imgh is half of the diagonal length of the effective photosensitive area on the imaging surface of the optical system. It can be understood that Imgh determines the size of the electronic photosensitive chip. The larger Imgh is, the larger the size of the maximum electronic photosensitive chip that the optical system can support. By satisfying that the value of FNO / (ImgH*2) is between 0mm -1 and 5mm -1 , the optical system can support a high-pixel electronic photosensitive chip; at the same time, a relatively large aperture number is provided, and a higher light input amount can be obtained. The optical system can more easily highlight the subject to be photographed and blur the background under telephoto shooting.

[0010] In one embodiment, the optical system satisfies the conditional formula: Y11 / Y72 < 0.6; where Y11 is the effective semi-aperture of the object side surface of the first lens, and Y72 is the effective semi-aperture of the image side surface of the seventh lens. By satisfying that the value of Y11 / Y72 is lower than 0.6, the effective aperture of the object side surface of the first lens is smaller, and the optical system has the characteristic of a small head size, which is beneficial to realizing a miniaturized design.

[0011] In one embodiment, the optical system satisfies the conditional formula: 1 < BF / CT67 < 3; where BF is the shortest distance from the image side surface of the seventh lens to the imaging surface, and CT67 is the distance between the image side surface of the sixth lens and the object side surface of the seventh lens on the optical axis. By satisfying that the value of BF / CT67 is between 1 and 3, good matching with the electronic photosensitive chip can be ensured, and at the same time, the sixth lens and the seventh lens have a reasonable distance, which helps to reduce aberration and improve resolution.

[0012] In one embodiment, the optical system satisfies the conditional formula: 6 < (Y72 * TTL) / (ET7 * f) < 13; where Y72 is the effective semi-aperture of the image side of the seventh lens, TTL is the distance from the object side of the first lens to the imaging surface of the optical system on the optical axis, ET7 is the thickness at the edge of the optical effective area of the seventh lens, and f is the effective focal length of the optical system. By satisfying that the value of (Y72 * TTL) / (ET7 * f) is between 6 and 13, the long focal length characteristic of the optical system and the total system length can be balanced, and while ensuring the molding yield of the seventh lens, the maximum diameter of the optical system can be reduced.

[0013] In one embodiment, the optical system satisfies the conditional formula: 0 < f123 / R32 < 10; where f123 is the combined effective focal length of the first lens, the second lens, and the third lens, and R32 is the curvature radius of the image side of the third lens on the optical axis. By satisfying that the value of f123 / R32 is between 0 and 10, the change in the curvature of the third lens rapidly compresses the aperture of the light in the optical system, which is beneficial for the subsequent lenses to further control the light; at the same time, a relatively large combined effective focal length from the first lens to the third lens is provided, which provides certain help for the improvement of the effective focal length of the optical system.

[0014] In one embodiment, the optical system satisfies the conditional formula: 2.5 < TTL / ∑AT < 4; where TTL is the distance from the object side of the first lens to the imaging surface of the optical system on the optical axis, and ∑AT is the sum of the air gaps on the optical axis between any two adjacent lenses from the first lens to the seventh lens. By satisfying that the value of TTL / ∑AT is between 2.5 and 4, it is beneficial to reduce the spacing between adjacent lenses on the optical axis within the processable range, thereby reducing the total system length and realizing the ultra-thin characteristic of the optical system. It can be understood that when TTL / ∑AT > 4, the spacing between adjacent lenses on the optical axis is too small, increasing the tolerance sensitivity, which is not conducive to lens assembly and increases the processing difficulty. When TTL / ∑AT < 2.5, the total system length is too short, which is not conducive to realizing the long focal length characteristic.

[0015] In one embodiment, the optical system satisfies the conditional formula: TTL / EPD < 3; where TTL is the distance from the object side of the first lens to the imaging surface of the optical system on the optical axis, and EPD is the entrance pupil diameter of the optical system. By satisfying that the value of TTL / EPD is less than 3, the total system length can be made smaller and the light input amount can be increased.

[0016] In one embodiment, the optical system satisfies the conditional formula: 0.5 < |f4567 / f| < 2; where f4567 is the combined effective focal length of the fourth lens, the fifth lens, the sixth lens, and the seventh lens, and f is the effective focal length of the optical system. By satisfying that the value of |f4567 / f| is between 0.5 and 2, it is beneficial to correct chromatic aberration and field curvature of the optical system, as well as slow down the light deflection angle, reduce sensitivity, and reduce the lens forming difficulty. It can be understood that when |f4567 / f| < 0.5, the combined effective focal length contributed by the fourth lens to the seventh lens to the entire system is too small, causing excessive light deflection and being unfavorable for aberration correction, ultimately resulting in a decrease in imaging quality. When |f4567 / f| > 2, the total length of the fourth lens to the seventh lens accounts for too high a proportion of the total system length, which is not conducive to system miniaturization; moreover, the overall bending power of the fourth lens to the seventh lens is insufficient, making it difficult to effectively balance the aberration of the first lens and the second lens as a whole.

[0017] In one embodiment, the optical system satisfies the conditional formula: Y11 / f < 0.3; where Y11 is the effective semi-aperture of the object side of the first lens, and f is the effective focal length of the optical system. By satisfying that the value of Y11 / f is less than 0.3, when the effective focal length of the optical system is fixed, it can ensure that the aperture of the first lens is as small as possible, thus meeting the small head requirement and being beneficial to achieving miniaturization.

[0018] In a second aspect, the present invention further provides an imaging module. The imaging module includes a lens barrel, a photosensitive element, and the optical system according to any one of the embodiments in the first aspect. The first lens to the seventh lens of the optical system are all installed in the lens barrel, and the photosensitive element is arranged on the image side of the optical system. By adding the optical system provided by the present invention to the imaging module, the imaging module can simultaneously meet the design requirements of miniaturization and telephoto imaging, which is beneficial for the imaging module to be applied to various small-sized photographing devices with high requirements for telephoto imaging.

[0019] In a third aspect, the present invention further provides an electronic device. The electronic device includes a housing and the imaging module described in the second aspect, and the imaging module is arranged in the housing. By adding the imaging module provided by the present invention to the electronic device, the electronic device can meet the design requirements of a thinner body and a smaller volume, and at the same time can perform high-definition imaging of distant views. Description of the Drawings

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings 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.

[0021] Figure 1a is a schematic structural diagram of the optical system of the first embodiment;

[0022] Figure 1b are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the first embodiment;

[0023] Figure 2a is a schematic structural diagram of the optical system of the second embodiment;

[0024] Figure 2b are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the second embodiment;

[0025] Figure 3a is a schematic structural diagram of the optical system of the third embodiment;

[0026] Figure 3b are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the third embodiment;

[0027] Figure 4a is a schematic structural diagram of the optical system of the fourth embodiment;

[0028] Figure 4b are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the fourth embodiment;

[0029] Figure 5a is a schematic structural diagram of the optical system of the fifth embodiment;

[0030] Figure 5b are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the fifth embodiment. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] The embodiments of the present invention provide an electronic device, which includes a housing and the camera module provided by the embodiments of the present invention, and the camera module is disposed in the housing. The electronic device can be a smart phone, a personal digital assistant (PDA), a tablet computer, a smart watch, a drone, an e-book reader, a driving recorder, a wearable device, a monitoring device, various driving assistance systems, etc. By adding the camera module provided by the present invention to the electronic device, the electronic device can meet the design requirements of a thinner body and a smaller volume, and at the same time can perform high-definition imaging of distant views.

[0033] An embodiment of the present invention provides an imaging module. The imaging module includes a lens barrel, an electronic photosensitive element, and the optical system provided by the embodiment of the present invention. The first lens to the seventh lens of the optical system are installed in the lens barrel, and the electronic photosensitive element is arranged on the image side of the optical system, and is used to convert the light of an object incident on the electronic photosensitive element through the first lens to the seventh lens into an electrical signal of an image. The electronic photosensitive element may be a Complementary Metal Oxide Semiconductor (CMOS) or a Charge-coupled Device (CCD). The imaging module may be an independent lens of a digital camera or an imaging module integrated on an electronic device such as a smart phone. By adding the optical system provided by the present invention to the imaging module, the imaging module can simultaneously meet the design requirements of miniaturization and telephoto imaging, which is beneficial to the application of the imaging module in various small-sized photographing devices with high requirements for telephoto imaging.

[0034] The present invention provides an optical system, which sequentially includes from the object side to the image side:

[0035] A first lens, having a positive refractive power, and the object side surface of the first lens is convex near the optical axis;

[0036] A second lens, having a refractive power;

[0037] A third lens, having a refractive power, and the image side surface of the third lens is concave near the optical axis;

[0038] A fourth lens, having a negative refractive power, the object side surface of the fourth lens is convex near the optical axis, and the image side surface of the fourth lens is concave near the optical axis;

[0039] A fifth lens, having a refractive power, and the object side surface of the fifth lens is concave near the optical axis;

[0040] A sixth lens, having a refractive power, and the image side surface of the sixth lens is convex near the optical axis;

[0041] A seventh lens, having a negative refractive power, the image side surface of the seventh lens is concave near the optical axis, both the object side surface and the image side surface of the seventh lens are aspherical surfaces, and at least one of the object side surface and the image side surface of the seventh lens is provided with at least one inflection point.

[0042] By reasonably configuring the bending power and surface profile of the first to seventh lenses, and setting an anastigmatism point on the seventh lens, it is convenient to reduce the bending degree of the lens, thereby reducing the axial thickness of the lens, contributing to reducing the overall length of the system. The optical system can balance the effective focal length and the overall length of the system, thus having a sufficiently long effective focal length and a short overall length of the system, and can meet the requirements of miniaturization and telephoto imaging simultaneously.

[0043] In one embodiment, the optical system satisfies the conditional formula: f / TTL > 1; where f is the effective focal length of the optical system, and TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system. By satisfying that the value of f / TTL is higher than 1, the optical system has a longer effective focal length and thus has telephoto characteristics. Specifically, the value of f / TTL can be 1, 1.05, 1.1, 1.26, 2, 5, etc.

[0044] In one embodiment, the optical system satisfies the conditional formula: 0mm -1 <FNO / (ImgH*2)<5mm -1 ; where FNO is the aperture number of the optical system, and Imgh is half of the diagonal length of the effective photosensitive area on the imaging surface of the optical system. It can be understood that Imgh determines the size of the electronic photosensitive chip. The larger Imgh is, the larger the size of the maximum electronic photosensitive chip that the optical system can support. By satisfying that the value of FNO / (ImgH*2) is between 0mm -1 and 5mm -1 , the optical system can support a high-pixel electronic photosensitive chip; at the same time, a relatively large aperture number is provided, enabling a higher light input. The optical system can more easily highlight the subject and blur the background in telephoto shooting. Specifically, the value of FNO / (ImgH*2) can be 0mm -1 , 0.7mm -1 , 1.35mm -1 , 2.4mm -1 , 3.2mm -1 , 4.8mm -1 , 5mm -1 , etc.

[0045] In one embodiment, the optical system satisfies the conditional formula: Y11 / Y72 < 0.6; where Y11 is the effective semi-aperture of the object side surface of the first lens, and Y72 is the effective semi-aperture of the image side surface of the seventh lens. By satisfying that the value of Y11 / Y72 is lower than 0.6, the effective aperture of the object side surface of the first lens is smaller, and the optical system has the characteristic of a small head size, which is beneficial to realizing miniaturized design. Specifically, the value of Y11 / Y72 can be 0.6, 0.58, 0.54, 0.4, 0.3, etc.

[0046] In one embodiment, the optical system satisfies the conditional formula: 1 < BF / CT67 < 3; where BF is the shortest distance from the image side surface of the seventh lens to the imaging surface, and CT67 is the distance between the image side surface of the sixth lens and the object side surface of the seventh lens on the optical axis. By ensuring that the value of BF / CT67 is between 1 and 3, good matching with the electronic photosensitive chip can be ensured. At the same time, a reasonable distance between the sixth lens and the seventh lens helps to reduce aberration and improve resolution. Specifically, the value of BF / CT67 can be 1, 1.2, 1.5, 1.9, 2.4, 2.8, 3, etc.

[0047] In one embodiment, the optical system satisfies the conditional formula: 6 < (Y72 * TTL) / (ET7 * f) < 13; where Y72 is the effective semi-aperture of the image side surface of the seventh lens, TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system, ET7 is the thickness at the edge of the optical effective area of the seventh lens, and f is the effective focal length of the optical system. By ensuring that the value of (Y72 * TTL) / (ET7 * f) is between 6 and 13, the telephoto characteristics of the optical system and the total system length can be balanced, while ensuring the molding yield of the seventh lens and reducing the maximum diameter of the optical system. Specifically, the value of (Y72 * TTL) / (ET7 * f) can be 6, 7.5, 8.5, 9.2, 11, 12.2, 13, etc.

[0048] In one embodiment, the optical system satisfies the conditional formula: 0 < f123 / R32 < 10; where f123 is the combined effective focal length of the first lens, the second lens, and the third lens, and R32 is the curvature radius of the image side surface of the third lens on the optical axis. By ensuring that the value of f123 / R32 is between 0 and 10, the change in the curvature of the third lens rapidly compresses the aperture of the light in the optical system, facilitating the further control of the light by the subsequent lenses; at the same time, a relatively large combined effective focal length from the first lens to the third lens is provided, which helps to increase the effective focal length of the optical system. Specifically, the value of f123 / R32 can be 0, 1, 3, 5, 8, 10, etc.

[0049] In one embodiment, the optical system satisfies the conditional expression: 2.5 < TTL / ∑AT < 4; where TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system, and ∑AT is the sum of the air spaces on the optical axis between any two adjacent lenses from the first lens to the seventh lens. By satisfying that the value of TTL / ∑AT is between 2.5 and 4, it is beneficial to reduce the spacing between adjacent lenses on the optical axis within the machinable range, thereby reducing the overall system length and achieving the ultra-thin characteristic of the optical system. It can be understood that when TTL / ∑AT > 4, the spacing between adjacent lenses on the optical axis is too small, increasing the tolerance sensitivity, which is not conducive to lens assembly and increases the processing difficulty. When TTL / ∑AT < 2.5, the overall system length is too short, which is not conducive to achieving the long focal length characteristic. Specifically, the value of TTL / ∑AT can be 2.5, 2.78, 3.15, 3.54, 3.8, 4, etc.

[0050] In one embodiment, the optical system satisfies the conditional expression: TTL / EPD < 3; where TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system, and EPD is the entrance pupil diameter of the optical system. By satisfying that the value of TTL / EPD is less than 3, the overall system length can be made smaller and the light incident amount can be increased. Specifically, the value of TTL / EPD can be 3, 2.5, 2.1, 1.8, 1.5, 1, 0.2, etc.

[0051] In one embodiment, the optical system satisfies the conditional expression: 0.5 < |f4567 / f| < 2; where f4567 is the combined effective focal length of the fourth lens, the fifth lens, the sixth lens, and the seventh lens, and f is the effective focal length of the optical system. By satisfying that the value of |f4567 / f| is between 0.5 and 2, it is beneficial to correct the chromatic aberration and field curvature of the optical system, as well as slow down the light deflection angle, reduce the sensitivity, and reduce the lens forming difficulty. It can be understood that when |f4567 / f| < 0.5, the combined effective focal length contributed by the fourth lens to the seventh lens to the entire system is too small, causing excessive light deflection, which is also not conducive to aberration correction, and finally resulting in a reduction in imaging quality. When |f4567 / f| > 2, the total length of the fourth lens to the seventh lens accounts for too high a proportion of the overall system length, which is not conducive to system miniaturization; moreover, the overall bending power of the fourth lens to the seventh lens is insufficient, making it difficult to effectively balance the aberrations of the first lens and the second lens as a whole. Specifically, the value of |f4567 / f| can be 0.5, 0.8, 1.2, 1.5, 1.8, 2, etc.

[0052] In one embodiment, the optical system satisfies the conditional formula: Y11 / f < 0.3; where Y11 is the effective semi-aperture of the object side surface of the first lens, and f is the effective focal length of the optical system. By satisfying that the value of Y11 / f is lower than 0.3, when the effective focal length of the optical system is fixed, it can ensure that the aperture of the first lens is as small as possible, thus meeting the requirement of a small head and facilitating miniaturization. Specifically, the value of Y11 / f can be 0.3, 0.28, 0.21, 0.15, 0.04, etc.

[0053] First Embodiment

[0054] Please refer to Figure 1a and Figure 1b , the optical system of this embodiment sequentially includes, from the object side to the image side:

[0055] The first lens L1, having a positive refractive power. The object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is concave near the optical axis;

[0056] The second lens L2, having a positive refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is convex near the optical axis;

[0057] The third lens L3, having a negative refractive power. The object side surface S5 of the third lens L3 is concave near the optical axis, and the image side surface S6 is concave near the optical axis;

[0058] The fourth lens L4, having a negative refractive power. The object side surface S7 of the fourth lens L4 is convex near the optical axis, and the image side surface S8 is concave near the optical axis;

[0059] The fifth lens L5, having a negative refractive power. The object side surface S9 of the fifth lens L5 is concave near the optical axis, and the image side surface S10 is concave near the optical axis.

[0060] The sixth lens L6, having a positive refractive power. The object side surface S11 of the sixth lens L6 is convex near the optical axis, and the image side surface S12 is convex near the optical axis.

[0061] The seventh lens L7, having a negative refractive power. The object side surface S13 of the seventh lens L7 is concave near the optical axis, and the image side surface S14 is concave near the optical axis.

[0062] The materials of the above-mentioned first lens L1 to seventh lens L7 are all plastics, which can help the optical system achieve a lightweight design.

[0063] In addition, the optical system further includes a diaphragm ST0, an infrared filter IR, and an imaging surface IMG. The diaphragm ST0 is disposed on the object side of the first lens L1 and can be provided at the circumference of the first lens L1, on the object side surface S1 of the first lens L1, or at a position spaced apart from the object side surface S1 of the first lens L1. The diaphragm STO is used to control the amount of incident light. In other embodiments, the diaphragm ST0 can also be provided on the object side surface and the image side surface of other lenses. The infrared filter IR is disposed on the image side of the seventh lens L7 and includes an object side surface S15 and an image side surface S16. The infrared filter IR is used to filter out infrared light so that the light incident on the imaging surface IMG is visible light, and the wavelength of the visible light is 380 nm - 780 nm. The material of the infrared filter IR is glass and a film can be coated on the glass. The imaging surface IMG is the image surface of the optical system, and most of its area overlaps with the effective pixel area of the electronic photosensitive element.

[0064] Table 1a shows a table of the characteristics of the optical system of this embodiment, and the data therein are obtained using light with a wavelength of 587.5618 nm. The units of the Y radius, thickness, and focal length are all millimeters (mm).

[0065] Table 1a

[0066]

[0067] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, Semi-FOV is half of the maximum field of view angle of the optical system in the diagonal direction of the electronic photosensitive element, and TTL is the distance on the optical axis from the object side surface S1 of the first lens L1 to the imaging surface IMG.

[0068] In this embodiment, the object side surfaces and the image side surfaces of each of the first lens L1 to the seventh lens L7 are aspherical surfaces. The surface profile x of the aspherical lens can be defined by, but not limited to, the following aspherical formula:

[0069]

[0070] Among them, x is the maximum sagitta distance from the vertex of the aspherical surface when the aspherical surface is along the optical axis direction 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 Y radius R in Table 1a above); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspherical surface.

[0071] Table 1b gives the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each aspherical mirror surface in the first embodiment.

[0072] Table 1b

[0073]

[0074] Figure 1b The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the first embodiment are shown. The ray reference wavelengths of the astigmatism curve and the distortion curve are 587.5618 nm. Among them, the longitudinal spherical aberration curve represents the deviation of the focusing points of rays with different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image plane curvature and the sagittal image plane curvature; the distortion curve represents the distortion magnitude values corresponding to different field angles. According to Figure 1b it can be known that the optical system given in the first embodiment can achieve good imaging quality.

[0075] Second Embodiment

[0076] Please refer to Figure 2a and Figure 2b , the optical system of this embodiment sequentially includes, from the object side to the image side:

[0077] The first lens L1, having a positive refractive power, the object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is concave near the optical axis;

[0078] The second lens L2, having a positive refractive power, the object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is convex near the optical axis;

[0079] The third lens L3, having a negative refractive power, the object side surface S5 of the third lens L3 is convex near the optical axis, and the image side surface S6 is concave near the optical axis;

[0080] The fourth lens L4, having a negative refractive power, the object side surface S7 of the fourth lens L4 is convex near the optical axis, and the image side surface S8 is concave near the optical axis;

[0081] The fifth lens L5, having a positive refractive power, the object side surface S9 of the fifth lens L5 is concave near the optical axis, and the image side surface S10 is convex near the optical axis.

[0082] The sixth lens L6, having a negative refractive power, the object side surface S11 of the sixth lens L6 is concave near the optical axis, and the image side surface S12 is convex near the optical axis.

[0083] The seventh lens L7, having a negative refractive power, the object side surface S13 of the seventh lens L7 is convex near the optical axis, and the image side surface S14 is concave near the optical axis.

[0084] Table 2a shows a table of the characteristics of the optical system of this embodiment, where the data are obtained using rays with a wavelength of 587.5618 nm, and the units of the Y radius, thickness, and focal length are all millimeters (mm).

[0085] Table 2a

[0086]

[0087]

[0088] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, Semi-FOV is half of the maximum field angle of the optical system in the diagonal direction of the electronic photosensitive element, and TTL is the distance on the optical axis from the object side surface S1 of the first lens L1 to the imaging surface IMG.

[0089] Table 2b gives the coefficients of the higher-order terms of the aspherical mirrors that can be used in the second embodiment. Among them, the aspherical surface types can be defined by the formulas given in the first embodiment.

[0090] Table 2b

[0091]

[0092] Figure 2b shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the second embodiment. The ray reference wavelength of the astigmatism curve and the distortion curve is 587.5618 nm. According to Figure 2b it can be seen that the optical system given in the second embodiment can achieve good imaging quality.

[0093] Third Embodiment

[0094] Please refer to Figure 3a and Figure 3b , the optical system of this embodiment sequentially includes, from the object side to the image side:

[0095] The first lens L1 has a positive refractive power. The object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is concave near the optical axis;

[0096] The second lens L2 has a positive refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is concave near the optical axis;

[0097] The third lens L3 has a positive refractive power. The object side surface S5 of the third lens L3 is convex near the optical axis, and the image side surface S6 is concave near the optical axis;

[0098] The fourth lens L4 has a negative refractive power. The object side surface S7 of the fourth lens L4 is convex near the optical axis, and the image side surface S8 is concave near the optical axis;

[0099] The fifth lens L5 has a positive refractive power. The object side surface S9 of the fifth lens L5 is concave near the optical axis, and the image side surface S10 is convex near the optical axis.

[0100] The sixth lens L6 has a negative refractive power. The object side S11 of the sixth lens L6 is concave near the optical axis, and the image side S12 is convex near the optical axis.

[0101] The seventh lens L7 has a negative refractive power. The object side S13 of the seventh lens L7 is convex near the optical axis, and the image side S14 is concave near the optical axis.

[0102] Table 3a shows a table of the characteristics of the optical system of this embodiment, where the data are obtained with light of a wavelength of 587.5618 nm. The units of the Y radius, thickness, and focal length are all millimeters (mm).

[0103] Table 3a

[0104]

[0105] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, Semi-FOV is half of the maximum field angle of the optical system in the diagonal direction of the electronic photosensitive element, and TTL is the distance on the optical axis from the object side S1 of the first lens L1 to the imaging surface IMG.

[0106] Table 3b gives the higher-order term coefficients of the aspherical mirror surfaces that can be used in the third embodiment. Among them, the aspherical surface types can be defined by the formulas given in the first embodiment.

[0107] Table 3b

[0108]

[0109] Figure 3b Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the third embodiment. The light reference wavelength of the astigmatism curve and the distortion curve is 587.5618 nm. According to Figure 3b It can be seen that the optical system given in the third embodiment can achieve good imaging quality.

[0110] Fourth Embodiment

[0111] Please refer to Figure 4a and Figure 4b , the optical system of this embodiment includes, in order from the object side to the image side:

[0112] The first lens L1 has a positive refractive power. The object side S1 of the first lens L1 is convex near the optical axis, and the image side S2 is convex near the optical axis;

[0113] The second lens L2 has a negative refractive power. The object side S3 of the second lens L2 is concave near the optical axis, and the image side S4 is convex near the optical axis;

[0114] The third lens L3 has a negative refractive power. The object side surface S5 of the third lens L3 is convex near the optical axis, and the image side surface S6 of the third lens L3 is concave near the optical axis;

[0115] The fourth lens L4 has a negative refractive power. The object side surface S7 of the fourth lens L4 is convex near the optical axis, and the image side surface S8 of the fourth lens L4 is concave near the optical axis;

[0116] The fifth lens L5 has a positive refractive power. The object side surface S9 of the fifth lens L5 is concave near the optical axis, and the image side surface S10 of the fifth lens L5 is convex near the optical axis.

[0117] The sixth lens L6 has a negative refractive power. The object side surface S11 of the sixth lens L6 is concave near the optical axis, and the image side surface S12 of the sixth lens L6 is convex near the optical axis.

[0118] The seventh lens L7 has a negative refractive power. The object side surface S13 of the seventh lens L7 is convex near the optical axis, and the image side surface S14 of the seventh lens L7 is concave near the optical axis.

[0119] Table 4a shows a table of the characteristics of the optical system of this embodiment, where the data are obtained with light rays of a wavelength of 587.5618 nm. The units of the Y radius, thickness, and focal length are all millimeters (mm).

[0120] Table 4a

[0121]

[0122] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, Semi-FOV is half of the maximum field of view angle of the optical system in the diagonal direction of the electronic photosensitive element, and TTL is the distance on the optical axis from the object side surface S1 of the first lens L1 to the imaging surface IMG.

[0123] Table 4b gives the high-order term coefficients that can be used for each aspherical mirror surface in the fourth embodiment. Among them, each aspherical surface type can be defined by the formula given in the first embodiment.

[0124] Table 4b

[0125]

[0126] Figure 4b Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the fourth embodiment. The reference wavelength of the light rays for the astigmatism curve and distortion curve is 587.5618 nm. According to Figure 4b It can be seen that the optical system given in the fourth embodiment can achieve good imaging quality.

[0127] The fifth embodiment

[0128] Please refer to Figure 5a andFigure 5b The optical system of this embodiment sequentially includes, from the object side to the image side:

[0129] The first lens L1, having a positive refractive power, the object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is concave near the optical axis;

[0130] The second lens L2, having a positive refractive power, the object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is convex near the optical axis;

[0131] The third lens L3, having a negative refractive power, the object side surface S5 of the third lens L3 is convex near the optical axis, and the image side surface S6 is concave near the optical axis;

[0132] The fourth lens L4, having a negative refractive power, the object side surface S7 of the fourth lens L4 is convex near the optical axis, and the image side surface S8 is concave near the optical axis;

[0133] The fifth lens L5, having a positive refractive power, the object side surface S9 of the fifth lens L5 is concave near the optical axis, and the image side surface S10 is convex near the optical axis.

[0134] The sixth lens L6, having a negative refractive power, the object side surface S11 of the sixth lens L6 is concave near the optical axis, and the image side surface S12 is convex near the optical axis.

[0135] The seventh lens L7, having a negative refractive power, the object side surface S13 of the seventh lens L7 is convex near the optical axis, and the image side surface S14 is concave near the optical axis.

[0136] Table 5a shows a table of the characteristics of the optical system of this embodiment, where the data is obtained with light of a wavelength of 587.5618 nm, and the units of the Y radius, thickness, and focal length are all millimeters (mm).

[0137] Table 5a

[0138]

[0139] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, Semi-FOV is half of the maximum field of view angle of the optical system in the diagonal direction of the electronic photosensitive element, and TTL is the distance on the optical axis from the object side surface S1 of the first lens L1 to the imaging surface IMG.

[0140] Table 5b gives the high-order term coefficients that can be used for each aspherical mirror surface in the fifth embodiment, where each aspherical surface type can be defined by the formula given in the first embodiment.

[0141] Table 5b

[0142]

[0143]

[0144] Figure 5b Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the fifth embodiment. The reference wavelength of the light rays for the astigmatism curve and distortion curve is 587.5618 nm. According to Figure 5b It can be seen that the optical system given in the fifth embodiment can achieve good imaging quality.

[0145] Table 6 shows the values of f / TTL, FNO / (ImgH*2), Y11 / Y72, BF / CT67, (Y72*TTL) / (ET7*f), f123 / R32, TTL / ∑AT, TTL / EPD, |f4567 / f|, and Y11 / f of the optical systems in the first to fifth embodiments. Among them, the unit of FNO / (ImgH*2) is millimeters -1 (mm -1 )

[0146] Table 6

[0147] f / TTL FNO / (ImgH*2) Y11 / Y72 BF / CT67 (Y72*TTL) / (ET7*f) First Embodiment 1.04 0.38 0.55 2.32 6.75 Second Embodiment 1.01 0.36 0.50 2.86 7.40 Third Embodiment 1.02 0.32 0.51 1.23 11.31 Fourth Embodiment 1.04 0.32 0.55 1.13 10.55 Fifth Embodiment 1.02 0.30 0.57 2.11 12.75 f123 / R32 TTL / ∑AT TTL / EPD |f4567 / f| Y11 / f First Embodiment 1.28 3.61 2.65 1.14 0.18 Second Embodiment 9.68 3.35 2.56 1.36 0.19 Third Embodiment 0.37 2.88 2.30 0.52 0.21 Fourth Embodiment 0.62 2.90 2.22 0.66 0.22 Fifth Embodiment 1.83 3.20 2.15 1.76 0.23

[0148] As can be seen from Table 6, the optical systems in the first to fifth embodiments all satisfy the following conditional expressions: f / TTL > 1.0 mm -1 <FNO / (ImgH*2)<5 mm -1 、Y11 / Y72 < 0.6, 1 < BF / CT67 < 3, 6 < (Y72*TTL) / (ET7*f) < 13, 0 < f123 / R32 < 10, 2.5 < TTL / ∑AT < 4, TTL / EPD < 3, 0.5 < |f4567 / f| < 2, Y11 / f < 0.3.

[0149] The above-disclosed are only some preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Those of ordinary skill in the art can understand the entire or partial processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.

Claims

1. An optical system, characterized in that, There are a total of seven lenses with refractive power, which successively include from the object side to the image side: The first lens, which has a positive refractive power, and the object side surface of the first lens is convex near the optical axis; The second lens, which has refractive power; The third lens, which has refractive power, and the image side surface of the third lens is concave near the optical axis; The fourth lens, which has a negative refractive power, the object side surface of the fourth lens is convex near the optical axis, and the image side surface of the fourth lens is concave near the optical axis; The fifth lens, which has refractive power, and the object side surface of the fifth lens is concave near the optical axis; The sixth lens, which has refractive power, and the image side surface of the sixth lens is convex near the optical axis; The seventh lens, which has a negative refractive power, the image side surface of the seventh lens is concave near the optical axis, both the object side surface and the image side surface of the seventh lens are aspherical, and at least one of the object side surface and the image side surface of the seventh lens is provided with at least one inflection point; The optical system satisfies the conditional formula: 0.5 ≤ Y11 / Y72 < 0.6; Wherein, Y11 is the effective semi-aperture of the object side surface of the first lens, and Y72 is the effective semi-aperture of the image side surface of the seventh lens.

2. The optical system according to claim 1, characterized in that, The optical system satisfies the conditional formula: f / TTL > 1; Wherein, f is the effective focal length of the optical system, and TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system.

3. The optical system according to claim 1, wherein, The optical system satisfies the conditional formula: 0 mm -1 <FNO / (Imgh * 2) < 5 mm -1 ; Wherein, FNO is the f-number of the optical system, and Imgh is half of the diagonal length of the effective photosensitive area on the imaging surface of the optical system.

4. The optical system according to claim 1, characterized in that, The optical system satisfies the conditional formula: 1 < BF / CT67 < 3; Wherein, BF is the shortest distance from the image side surface of the seventh lens to the imaging surface, and CT67 is the distance on the optical axis between the image side surface of the sixth lens and the object side surface of the seventh lens.

5. The optical system according to claim 1, wherein The optical system satisfies the conditional formula: 6 < (Y72 * TTL) / (ET7 * f) < 13; Wherein, Y72 is the effective semi-aperture of the image side surface of the seventh lens, TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system, ET7 is the thickness of the edge of the optical effective area of the seventh lens, and f is the effective focal length of the optical system.

6. The optical system according to claim 1, characterized in that, The optical system satisfies the conditional formula: 0 < f123 / R32 < 10; Wherein, f123 is the combined effective focal length of the first lens, the second lens, and the third lens, and R32 is the radius of curvature of the image side surface of the third lens at the optical axis.

7. The optical system according to claim 1, characterized in that, The optical system satisfies the conditional formula: 2.5 < TTL / ∑AT < 4; Wherein, TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system, and ∑AT is the sum of the air gaps on the optical axis between any two adjacent lenses from the first lens to the seventh lens.

8. The optical system according to claim 1, characterized in that, The optical system satisfies the conditional formula: 2.15 ≤ TTL / EPD < 3; Wherein, TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system, and EPD is the entrance pupil diameter of the optical system.

9. The optical system according to claim 1, wherein The optical system satisfies the conditional formula: 0.5 < |f4567 / f| < 2; Wherein, f4567 is the combined effective focal length of the fourth lens, the fifth lens, the sixth lens and the seventh lens, and f is the effective focal length of the optical system.

10. The optical system according to claim 1, characterized in that, The optical system satisfies the conditional formula: 0.18 ≤ Y11 / f < 0.3; Wherein, Y11 is the effective semi-aperture of the object side surface of the first lens, and f is the effective focal length of the optical system.

11. An imaging module, characterized in that, It includes a lens barrel, a photosensitive element and the optical system according to any one of claims 1 to 10. The first lens to the seventh lens of the optical system are all installed in the lens barrel, and the photosensitive element is arranged on the image side of the optical system.

12. An electronic device, characterized in that, It includes a housing and the imaging module according to claim 11. The imaging module is arranged in the housing.

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