Optical systems, lens modules and electronic devices

Abstract

The present invention provides an optical system, a lens module and an electronic device. The optical system includes, from the object side to the image side along the optical axis direction: a first lens having positive refractive power, the object side surface of the first lens is convex near the optical axis, and the image side surface of the first lens is concave near the optical axis; a second lens having negative refractive power, the object side surface of the second lens is convex near the optical axis, and the image side surface of the second lens is concave near the optical axis; a third lens having refractive power; a fourth lens having refractive power; a fifth lens having negative refractive power, the image side surface of the fifth lens is concave near the optical axis, and the object side surface or the image side surface of the fifth lens has at least one inflection point; the optical system satisfies the conditional formula: ET2 / CT2<2; wherein ET2 is the edge thickness of the second lens, and CT2 is the center thickness of the second lens. The present invention solves the technical problem that a five-piece lens cannot meet the requirements of high pixel and high resolution.

Description

Technical Field

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

[0002] With the rapid advancement of technology, consumers are demanding increasingly higher image quality from mobile electronic products. Currently, five-element imaging lenses are relatively mature, but their pixels are small, and their resolution is increasingly insufficient to meet market demand. Consequently, consumers are increasingly seeking lenses with higher pixels and resolution. This is often achieved by using more lenses, but a larger number of lenses increases the manufacturing process complexity and costs. Existing five-element lenses cannot meet these high pixel and resolution requirements. Therefore, increasing the pixel and resolution within a five-element optical system design is a key factor in improving camera quality. Summary of the Invention

[0003] The purpose of the present application is to provide an optical system, a lens module and an electronic device for solving the above-mentioned technical problems. The present invention provides an optical system, which comprises, from the object side to the image side along the optical axis direction: a first lens having positive refractive power, the object side surface of the first lens is convex near the optical axis, and the image side surface of the first lens is concave near the optical axis; a second lens having negative refractive power, the object side surface of the second lens is convex near the optical axis, and the image side surface of the second lens is concave near the optical axis; a third lens having refractive power; a fourth lens having refractive power; a fifth lens having negative refractive power, the image side surface of the fifth lens is concave near the optical axis, and there is at least one inflection point on the object side or image side surface of the fifth lens; the optical system satisfies the conditional formula: ET2 / CT2<2; wherein ET2 is the edge thickness of the second lens, and CT2 is the center thickness of the second lens. The present application reasonably configures the surface shape and refractive power of each lens from the first lens to the fifth lens, so that the five-piece optical system can meet the requirements of high pixel and good image quality. When the optical system satisfies the above conditional expression, the ratio of the edge thickness of the second lens to the center thickness of the second lens can be reasonably controlled within a certain range, which is beneficial to the processing and production of the second lens.

[0004] In certain embodiments, the optical system satisfies the conditional equation: f*tan(HFOV)>4.1mm, where f is the focal length of the optical system and HFOV is the half field of view of the optical system. When the optical system satisfies this conditional equation, it can have a large image plane, resulting in high pixel count and high definition.

[0005] In some embodiments, the optical system satisfies the conditional formula: 1 < TTL / f < 1.5; where 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, and f is the focal length of the optical system. When the optical system satisfies the above conditional formula, the ratio of the total length of the optical system to the focal length can be reasonably controlled to be less than a certain range, enabling the system to have the characteristic of miniaturization. At the same time, controlling the ratio of the total length of the optical system to the focal length to be greater than a certain range can reduce the sensitivity of the optical system, which is beneficial to the processing and production of the product.

[0006] In some embodiments, the optical system satisfies the conditional formula: |R5 / R6| < 15; where R5 is the curvature radius of the object side surface of the third lens on the optical axis, and R6 is the curvature radius of the image side surface of the third lens on the optical axis. When the optical system satisfies the above conditional formula, the curvature radius of the object side surface and the curvature radius of the image side surface of the third lens can be reasonably controlled within a certain range, which is beneficial to the processing and shaping of the third lens and can effectively reduce the sensitivity of the optical system at the third lens.

[0007] In some embodiments, the optical system satisfies the conditional formula: |f1 / f| < 1.5; where f1 is the focal length of the first lens, and f is the focal length of the optical system. When the optical system satisfies the above conditional formula, the ratio of the focal length of the first lens to the focal length of the optical system can be reasonably controlled, and the position chromatic aberration of the optical system can be effectively corrected.

[0008] In some embodiments, the optical system satisfies the conditional formula: f / EPD < 2.0, where f is the focal length of the optical system, and EPD is the entrance pupil diameter of the optical system. When the optical system satisfies the above conditional formula, the optical system can have the characteristic of a large aperture, so that the optical system has a larger light entrance amount and improves the shooting effect under dark conditions.

[0009] In certain embodiments, the optical system satisfies the conditional formula: (L41p1-L41p2)-(L32p1-L32p2)<0.4mm, wherein L32p1 represents the maximum vertical distance between the intersection of the edge field of view and the image side surface of the third lens and the optical axis, L32p2 represents the minimum vertical distance between the intersection of the edge field of view and the image side surface of the third lens and the optical axis, L41p1 represents the maximum vertical distance between the intersection of the edge field of view and the object side surface of the fourth lens and the optical axis, and L41p2 represents the minimum vertical distance between the intersection of the edge field of view and the object side surface of the fourth lens and the optical axis, and the edge field of view is the light beam that is incident and converges onto the imaging surface of the optical imaging system at the point farthest from the optical axis. When the optical system satisfies the above conditional formula, the difference between the clear aperture of the object side surface of the fourth lens and the clear aperture of the image side surface of the third lens can be reasonably controlled within a certain range, which can effectively reduce the fault difference between the third and fourth lens structures, make the edge field of view light smoother, and facilitate product processing and production stability.

[0010] In certain embodiments, the optical system satisfies the conditional equation: |R5|>27, where R5 is the radius of curvature of the object side surface of the third lens at the optical axis. When the optical system satisfies this conditional equation, the radius of curvature of the object side surface of the third lens can be reasonably controlled within a certain range, which is beneficial for improving imaging quality.

[0011] The present invention provides a lens module comprising a lens barrel, an electronic photosensitive element, and the optical system described above. The first through fifth lenses of the optical system are mounted within the lens barrel, and the electronic photosensitive element is disposed on the image side of the optical system, configured to convert light from an object that passes through the first through fifth lenses and is incident on the electronic photosensitive element into an electrical signal representing an image. By mounting the first through fifth lenses of the optical system within the lens module and rationally configuring the surface shape and refractive power of each of the first through fifth lenses, the present application enables a five-lens optical system to meet both high pixel and high resolution requirements.

[0012] The present invention provides an electronic device, comprising a housing and the above-mentioned lens module, wherein the lens module is disposed in the housing. By disposing the above-mentioned lens module in the electronic device, the electronic device can meet the requirements of high pixel and high resolution.

[0013] In summary, the present invention proposes a five-element large-image-surface, large-aperture optical system, which can enable the optical system to obtain high pixels and high resolution, and thus provide the optical system with better imaging effects; and the optical system design has the characteristics of a large aperture, which has a larger amount of light input compared to a camera lens, and can improve low-light shooting conditions. While meeting the requirements of high-definition image shooting, it can also be suitable for shooting in low-light environments such as night scenes, rainy days, and starry skies, and has better imaging effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1a is a schematic structural diagram of the optical system of the first embodiment;

[0016] Figure 1b 1. The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the first embodiment;

[0017] Figure 2a is a schematic structural diagram of the optical system of the second embodiment;

[0018] Figure 2b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the second embodiment;

[0019] Figure 3a is a schematic structural diagram of an optical system according to a third embodiment;

[0020] Figure 3b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the third embodiment;

[0021] Figure 4a is a schematic structural diagram of an optical system according to a fourth embodiment;

[0022] Figure 4b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the fourth embodiment;

[0023] Figure 5a is a schematic structural diagram of an optical system according to a fifth embodiment;

[0024] Figure 5b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the fifth embodiment;

[0025] Figure 6a is a schematic structural diagram of the optical system of the sixth embodiment;

[0026] Figure 6b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the sixth embodiment;

[0027] Figure 7 This is a schematic diagram of the optical system and light path provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] An embodiment of the present application provides a lens module, which includes a lens barrel, an electronic photosensitive element and an optical system provided by an embodiment of the present invention, wherein the first lens to the fifth 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 the object incident on the electronic photosensitive element through the first lens to the fifth lens into an electrical signal of an image. The electronic photosensitive element can be a complementary metal oxide semiconductor (CMOS) or a charge-coupled device (CCD). The lens module can be an independent lens of a digital camera, or an imaging module integrated in an electronic device such as a smartphone. The present application can make a five-piece optical system meet the requirements of high pixel and high resolution by installing the first lens to the fifth lens of the optical system in the lens module and reasonably configuring the surface shape and refractive power of each lens of the first lens to the fifth lens.

[0030] An embodiment of the present application provides an electronic device, comprising a housing and a lens module provided in an embodiment of the present application. The lens module and the electronic photosensitive element are disposed within the housing. The electronic device may be a smartphone, a personal digital assistant (PDA), a tablet computer, a smartwatch, a drone, an e-book reader, a driving recorder, a wearable device, or the like. By providing a lens module in the electronic device, the present application enables the electronic device to meet the requirements of high pixel and high resolution.

[0031] The present invention provides an optical system comprising, in order from the object side to the image side along the optical axis, a stop, a first lens, a second lens, a third lens, a fourth lens, and a fifth lens. Among the first to fifth lenses, any two adjacent lenses may have an air gap between them.

[0032] Specifically, the specific shape and structure of the five lenses are as follows:

[0033] The first lens has a positive refractive power. The object side of the first lens near the optical axis is convex, and the image side of the first lens near the optical axis is concave. The second lens has a negative refractive power. The object side of the second lens near the optical axis is convex, and the image side of the second lens near the optical axis is concave. The third lens has a refractive power. The fourth lens has a refractive power. The fifth lens has a negative refractive power. The image side of the fifth lens near the optical axis is concave, and there is at least one inflection point on the object side or the image side of the fifth lens. The optical system satisfies the conditional formula: ET2 / CT2 < 2; where ET2 is the edge thickness of the second lens, and CT2 is the central thickness of the second lens. In this application, by reasonably configuring the surface types and refractive powers of the first lens to the fifth lens, the five-piece optical system can meet the requirements of high pixels and good image quality. When the optical system satisfies the above conditional formula, the ratio of the edge thickness of the second lens to the central thickness of the second lens can be reasonably controlled within a certain range, which is beneficial to the processing and production of the second lens.

[0034] In a specific embodiment, the optical system satisfies the conditional formula: f * tan(HFOV) > 4.1 mm; where f is the focal length of the optical system, and HFOV is the half field angle of the optical system. When the optical system satisfies the above conditional formula, the optical system can have the characteristic of a large image plane, so that the optical system has high pixels and high definition.

[0035] In a specific embodiment, the optical system satisfies the conditional formula: 1 < TTL / f < 1.5; where TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis, and f is the focal length of the optical system. When the optical system satisfies the above conditional formula, the ratio of the total length of the optical system to the focal length can be reasonably controlled to be less than a certain range, which can make the system have the characteristic of miniaturization. At the same time, controlling the ratio of the total length of the optical system to the focal length to be greater than a certain range can weaken the sensitivity of the optical system, which is beneficial to the processing and production of the product.

[0036] In a specific embodiment, the optical system satisfies the conditional formula: |R5 / R6| < 15; where R5 is the radius of curvature of the object side of the third lens at the optical axis, and R6 is the radius of curvature of the image side of the third lens at the optical axis. When the optical system satisfies the above conditional formula, the radius of curvature of the object side and the radius of curvature of the image side of the third lens can be reasonably controlled within a certain range, which is beneficial to the processing and molding of the third lens and can effectively reduce the sensitivity of the optical system at the third lens.

[0037] In a specific embodiment, the optical system satisfies the conditional equation: |f1 / f| < 1.5, where f1 is the focal length of the first lens, and f is the focal length of the optical system. When the optical system satisfies this conditional equation, the ratio of the focal lengths of the first lens and the optical system can be reasonably controlled, effectively correcting positional chromatic aberration of the optical system.

[0038] In a specific embodiment, the optical system satisfies the conditional formula: f / EPD < 2.0, where f is the focal length of the optical system and EPD is the entrance pupil diameter of the optical system. When the optical system satisfies this conditional formula, the optical system can have a large aperture, thereby allowing the optical system to receive more light and improving photography in dark conditions.

[0039] See also Figure 7 In a specific embodiment, the optical system satisfies the conditional formula: (L41p1-L41p2)-(L32p1-L32p2)<0.4mm, wherein L32p1 represents the maximum vertical distance between the intersection of the edge field of view and the image side surface of the third lens and the optical axis, L32p2 represents the minimum vertical distance between the intersection of the edge field of view and the image side surface of the third lens and the optical axis, L41p1 represents the maximum vertical distance between the intersection of the edge field of view and the object side surface of the fourth lens and the optical axis, and L41p2 represents the minimum vertical distance between the intersection of the edge field of view and the object side surface of the fourth lens and the optical axis. The edge field of view is the light beam that is incident on and converges to the imaging surface of the optical imaging system at the point farthest from the optical axis. When the optical system satisfies the above conditional formula, the difference between the clear aperture of the object side surface of the fourth lens and the clear aperture of the image side surface of the third lens can be reasonably controlled within a certain range, which can effectively reduce the fault difference between the third and fourth lens structures, make the edge field of view light smoother, and facilitate product processing and production stability.

[0040] In a specific embodiment, the optical system satisfies the conditional equation: |R5|>27, where R5 is the radius of curvature of the object side surface of the third lens at the optical axis. When the optical system satisfies this conditional equation, the radius of curvature of the object side surface of the third lens can be reasonably controlled within a certain range, which is beneficial for improving imaging quality.

[0041] First embodiment,

[0042] Please refer to Figure 1a and Figure 1b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0043] The first lens L1 has 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. The object-side surface S1 of the first lens L1 is convex at the circumference, and the image-side surface S2 is convex at the circumference.

[0044] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 is convex near the optical axis, and the image-side surface S4 is concave near the optical axis. The object-side surface S3 of the second lens element L2 is convex at the circumference, and the image-side surface S4 is concave at the circumference.

[0045] The third lens L3 has positive 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 convex near the optical axis. The object-side surface S5 of the third lens L3 is concave at the circumference, and the image-side surface S6 is convex at the circumference.

[0046] The fourth lens L4 has positive refractive power. The object-side surface S7 of the fourth lens L4 is concave near the optical axis, and the image-side surface S8 is convex near the optical axis. The object-side surface S7 of the fourth lens L4 is concave at the circumference, and the image-side surface S8 is convex at the circumference.

[0047] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 is convex near the optical axis, and the image-side surface S10 is concave near the optical axis. The object-side surface S9 of the fifth lens element L5 is convex along the circumference, and the image-side surface S10 is convex along the circumference.

[0048] The first lens L1 to the fifth lens L5 are all made of plastic.

[0049] In addition, the optical system also includes an aperture STO, an infrared filter L6 and an image plane S13. The aperture STO is arranged on the side of the first lens L1 away from the second lens L2, and is used to control the amount of light entering. In other embodiments, the aperture STO can also be arranged between two adjacent lenses, or on other lenses. The infrared filter L6 is arranged on the image side of the fifth lens L5, and includes an object side surface S11 and an image side surface S12. The infrared filter L6 is used to filter out infrared light so that the light incident on the image plane S13 is visible light, and the wavelength of visible light is 380nm-780nm. The material of the infrared filter L6 is glass, and a film can be coated on the glass. The image plane S13 is the surface where the image of the object is formed after the light passes through the optical system.

[0050] Table 1a shows the characteristics of the optical system of this embodiment, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0051] Table 1a

[0052]

[0053]

[0054] Wherein, f is the focal length of the optical system, FNO is the aperture number of the optical system, FOV is the field of view of the optical system, and TTL is the distance from the object side surface of the first lens to the imaging plane of the optical system on the optical axis.

[0055] In this embodiment, the object-side surface and the image-side surface of any lens from the first lens L1 to the fifth lens L5 are aspherical surfaces. The surface shape x of each aspherical lens can be defined by, but is not limited to, the following aspherical surface formula:

[0056]

[0057] Where x is the distance vector from the vertex of the aspheric surface at a height h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., 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 for the i-th order of the aspheric surface. Table 1b lists the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 for each aspheric mirror surface S1-S14 that can be used in the first embodiment.

[0058] Table 1b

[0059]

[0060] Figure 1b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the first embodiment are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image curvature and sagittal image curvature; the distortion curve represents the distortion value corresponding to different field angles. Figure 1b It can be seen that the optical system provided in the first embodiment can achieve good imaging quality.

[0061] Second embodiment,

[0062] Please refer to Figure 2a and Figure 2b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0063] The first lens L1 has 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. The object-side surface S1 of the first lens L1 is convex at the circumference, and the image-side surface S2 is convex at the circumference.

[0064] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 is convex near the optical axis, and the image-side surface S4 is concave near the optical axis. The object-side surface S3 of the second lens element L2 is convex at the circumference, and the image-side surface S4 is concave at the circumference.

[0065] The third lens L3 has 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 convex near the optical axis. The object-side surface S5 of the third lens L3 is concave at the circumference, and the image-side surface S6 is convex at the circumference.

[0066] The fourth lens L4 has positive refractive power. The object-side surface S7 of the fourth lens L4 is concave at the near optical axis, and the image-side surface S8 is convex at the near optical axis. The object-side surface S7 of the fourth lens L4 is concave at the circumference, and the image-side surface S8 is convex at the circumference.

[0067] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 is convex near the optical axis, and the image-side surface S10 is concave near the optical axis. The object-side surface S9 of the fifth lens element L5 is convex along the circumference, and the image-side surface S10 is convex along the circumference.

[0068] The other structures of the second embodiment are the same as those of the first embodiment, and can be used as a reference.

[0069] Table 2a shows the characteristics of the optical system of this embodiment, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0070] Table 2a

[0071]

[0072] The meanings of the parameters in Table 2a are the same as those in the first embodiment.

[0073] Table 2b gives the high-order coefficients of each aspherical mirror surface that can be used in the second embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0074] Table 2b

[0075]

[0076] Figure 2b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment are shown. Figure 2b It can be seen that the optical system provided in the second embodiment can achieve good imaging quality.

[0077] Third embodiment

[0078] Please refer to Figure 3a and Figure 3b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0079] The first lens L1 has 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. The object-side surface S1 of the first lens L1 is convex at the circumference, and the image-side surface S2 is convex at the circumference.

[0080] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 is convex near the optical axis, and the image-side surface S4 is concave near the optical axis. The object-side surface S3 of the second lens element L2 is convex at the circumference, and the image-side surface S4 is concave at the circumference.

[0081] The third lens L3 has positive refractive power. The object-side surface S1 of the third lens L3 is concave near the optical axis, and the image-side surface S2 is convex near the optical axis. The object-side surface S5 of the third lens L3 is concave at the circumference, and the image-side surface S6 is convex at the circumference.

[0082] The fourth lens L4 has negative refractive power. The object-side surface S7 of the fourth lens L4 is concave near the optical axis, and the image-side surface S8 is convex near the optical axis. The object-side surface S7 of the fourth lens L4 is concave at the circumference, and the image-side surface S8 is convex at the circumference.

[0083] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 is convex near the optical axis, and the image-side surface S10 is concave near the optical axis. The object-side surface S9 of the fifth lens element L5 is convex along the circumference, and the image-side surface S10 is convex along the circumference.

[0084] The other structures of the third embodiment are the same as those of the first embodiment, and can be used as a reference.

[0085] Table 3a shows the characteristics of the optical system of this embodiment, where the units of Y radius, thickness and focal length are all millimeters (mm).

[0086] Table 3a

[0087]

[0088] The meanings of the parameters in Table 3a are the same as those in the first embodiment.

[0089] Table 3b gives the high-order coefficients of each aspheric mirror surface that can be used in the third embodiment, wherein each aspheric surface shape can be defined by the formula given in the first embodiment.

[0090] Table 3b

[0091]

[0092] Figure 3b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the third embodiment are shown. Figure 3bIt can be seen that the optical system provided in the third embodiment can achieve good imaging quality.

[0093] Fourth embodiment,

[0094] 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 along the optical axis:

[0095] The first lens L1 has 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. The object-side surface S1 of the first lens L1 is convex at the circumference, and the image-side surface S2 is convex at the circumference.

[0096] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 is convex near the optical axis, and the image-side surface S4 is concave near the optical axis. The object-side surface S3 of the second lens element L2 is convex at the circumference, and the image-side surface S4 is concave at the circumference.

[0097] The third lens L3 has positive refractive power. The object-side surface S1 of the third lens L3 is convex near the optical axis, and the image-side surface S2 is convex near the optical axis. The object-side surface S5 of the third lens L3 is concave at the circumference, and the image-side surface S6 is convex at the circumference.

[0098] The fourth lens L4 has positive refractive power. The object-side surface S7 of the fourth lens L4 is concave at the near optical axis, and the image-side surface S8 is convex at the near optical axis. The object-side surface S7 of the fourth lens L4 is concave at the circumference, and the image-side surface S8 is convex at the circumference.

[0099] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 is convex near the optical axis, and the image-side surface S10 is concave near the optical axis. The object-side surface S9 of the fifth lens element L5 is convex along the circumference, and the image-side surface S10 is convex along the circumference.

[0100] The other structures of the fourth embodiment are the same as those of the first embodiment, and can be used as a reference.

[0101] Table 4a shows the characteristics of the optical system of this embodiment, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0102] Table 4a

[0103]

[0104] The meanings of the parameters in Table 4a are the same as those in the first embodiment.

[0105] Table 4b gives the high-order coefficients of the aspheric mirror surfaces that can be used in the fourth embodiment, wherein the aspheric surface shapes can be defined by the formula given in the first embodiment.

[0106] Table 4b

[0107]

[0108] Figure 4b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment are shown. Figure 4b It can be seen that the optical system provided in the fourth embodiment can achieve good imaging quality.

[0109] The fifth embodiment,

[0110] Please refer to Figure 5a and Figure 5b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0111] The first lens L1 has 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. The object-side surface S1 of the first lens L1 is convex at the circumference, and the image-side surface S2 is convex at the circumference.

[0112] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 is convex near the optical axis, and the image-side surface S4 is concave near the optical axis. The object-side surface S3 of the second lens element L2 is convex at the circumference, and the image-side surface S4 is concave at the circumference.

[0113] The third lens L3 has positive 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 convex near the optical axis. The object-side surface S5 of the third lens L3 is concave at the circumference, and the image-side surface S6 is convex at the circumference.

[0114] The fourth lens L4 has positive 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 convex near the optical axis. The object-side surface S7 of the fourth lens L4 is concave at the circumference, and the image-side surface S8 is convex at the circumference.

[0115] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 is convex near the optical axis, and the image-side surface S10 is concave near the optical axis. The object-side surface S9 of the fifth lens element L5 is convex along the circumference, and the image-side surface S10 is convex along the circumference.

[0116] The other structures of the fifth embodiment are the same as those of the first embodiment, and can be referred to for reference.

[0117] Table 5a shows the characteristics of the optical system of this embodiment, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0118] Table 5a

[0119]

[0120]

[0121] The meanings of the parameters in Table 5a are the same as those in the first embodiment.

[0122] Table 5b gives the high-order coefficients of each aspherical mirror surface that can be used in the fifth embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0123] Table 5b

[0124]

[0125] Figure 5b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment are shown. Figure 5b It can be seen that the optical system provided in the fifth embodiment can achieve good imaging quality.

[0126] Sixth embodiment,

[0127] Please refer to Figure 6a and Figure 6b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0128] The first lens L1 has 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. The object-side surface S1 of the first lens L1 is convex at the circumference, and the image-side surface S2 is convex at the circumference.

[0129] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 is convex near the optical axis, and the image-side surface S4 is concave near the optical axis. The object-side surface S3 of the second lens element L2 is convex at the circumference, and the image-side surface S4 is concave at the circumference.

[0130] The third lens element L3 has negative refractive power. The object-side surface S1 of the third lens element L3 is concave near the optical axis, and the image-side surface S2 is concave near the optical axis. The object-side surface S5 of the third lens element L3 is concave at the circumference, and the image-side surface S6 is convex at the circumference.

[0131] The fourth lens L4 has positive 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 convex near the optical axis. The object-side surface S7 of the fourth lens L4 is concave at the circumference, and the image-side surface S8 is convex at the circumference.

[0132] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 is convex near the optical axis, and the image-side surface S10 is concave near the optical axis. The object-side surface S9 of the fifth lens element L5 is convex along the circumference, and the image-side surface S10 is convex along the circumference.

[0133] The other structures of the sixth embodiment are the same as those of the first embodiment, and can be used as a reference.

[0134] Table 6a shows the characteristics of the optical system of this embodiment, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0135] Table 6a

[0136]

[0137] The meanings of the parameters in Table 6a are the same as those in the first embodiment.

[0138] Table 6b gives the high-order coefficients of each aspheric mirror surface that can be used in the sixth embodiment, wherein each aspheric surface shape can be defined by the formula given in the first embodiment.

[0139] Table 6b

[0140]

[0141]

[0142] Figure 6b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the sixth embodiment are shown. Figure 6b It can be seen that the optical system provided in the sixth embodiment can achieve good imaging quality.

[0143] Table 7 shows the values ​​of f / EPD, f*tan(HFOV), TTL / f, |R5 / R6|, |f1 / f|, ET2 / CT2, (L41p1-L41p2)-(L32p1-L32p2), and |R5| of the optical systems of the first to sixth embodiments.

[0144] Table 7

[0145] f / EPD f*tan(HFOV) TTL / f |R5 / R6| First embodiment 1.99 4.14 1.18 1.60 Second embodiment 1.97 4.14 1.18 0.36 Third embodiment 1.99 4.14 1.19 3.20 Fourth embodiment 1.99 4.23 1.18 10.10 Fifth embodiment 1.99 4.14 1.18 1.36 Sixth embodiment 1.99 4.14 1.18 13.46 |f1 / f| ET2 / CT2 (L41p1-L41p2)-(L32p1-L32p2) |R5| First embodiment 0.81 1.45 0.35 |-35.27| Second embodiment 0.83 1.42 0.35 |-34| Third embodiment 0.81 1.49 0.36 |-27.97| Fourth embodiment 0.80 1.33 0.36 |1000| Fifth embodiment 0.84 1.46 0.34 |-71.15 / | Sixth embodiment 0.85 1.50 0.36 |-1346.29|

[0146] As can be seen from Table 7, all embodiments satisfy the following conditions: f / EPD<2.0, f*tan(HFOV)>4.1, 1 <TTL / f<1.5、|R5 / R6|<15、|f1 / f|<1.5、ET2 / CT2<2、(L41p1-L41p2)-(L32p1-L32p2)<0.4mm、|R5|>27。

[0147] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope of this specification.

[0148] The above embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An optical system, characterized in that: There are five lenses with refractive power in total, which successively include from the object side to the image side along the optical axis direction: The first lens, which has positive refractive power. The object side surface of the first lens is convex near the optical axis, and the image side surface of the first lens is concave near the optical axis. The second lens, which has negative refractive power. The object side surface of the second lens is convex near the optical axis, and the image side surface of the second lens is concave near the optical axis. The third lens, which has refractive power. The fourth lens, which has refractive power. The image side surface of the fourth lens is convex near the optical axis. The fifth lens, which has negative refractive power. The image side surface of the fifth lens is concave near the optical axis, and there is at least one inflection point on the object side surface or the image side surface of the fifth lens. The optical system satisfies the conditional formula: 1.33 ≤ ET2 / CT2 < 2; where ET2 is the edge thickness of the second lens, and CT2 is the center thickness of the second lens. 3.2 ≤ |R5 / R6| < 15; where R5 is the curvature radius of the object side surface of the third lens at the optical axis, and R6 is the curvature radius of the image side surface of the third lens at the optical axis. 4.1mm < f * tan(HFOV) ≤ 4.23mm; where f is the focal length of the optical system, and HFOV is the half field angle of view of the optical system.

2. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 1 < TTL / f < 1.5; where 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, and f is the focal length of the optical system.

3. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 1.33 ≤ ET2 / CT2 ≤ 1.

5.

4. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 0.80 ≤ |f1 / f| < 1.5; where f1 is the focal length of the first lens, and f is the focal length of the optical system.

5. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: f / EPD < 2.0, where f is the focal length of the optical system, and EPD is the entrance pupil diameter of the optical system.

6. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 0.36mm ≤ (L41p1 - L41p2) - (L32p1 - L32p2) < 0.4mm, where L32p1 represents the maximum perpendicular distance from the intersection point of the marginal field of view and the image side surface of the third lens to the optical axis, L32p2 represents the minimum perpendicular distance from the intersection point of the marginal field of view and the image side surface of the third lens to the optical axis, L41p1 represents the maximum perpendicular distance from the intersection point of the marginal field of view and the object side surface of the fourth lens to the optical axis, and L41p2 represents the minimum perpendicular distance from the intersection point of the marginal field of view and the object side surface of the fourth lens to the optical axis.

7. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 1346.29 ≥ |R5| > 27, where R5 is the curvature radius of the object side surface of the third lens at the optical axis.

8. A lens module, characterized in that: It includes a lens barrel, an electronic photosensitive element, and the optical system according to any one of claims 1 to 7. The first lens to the fifth lens of the optical system are installed in the lens barrel.

9. An electronic device, characterized in that: It includes a housing and the lens module according to claim 8. The lens module is arranged in the housing.

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