WO2022227016A1

WO2022227016A1 - Optical system, lens module, and electronic device

Info

Publication number: WO2022227016A1
Application number: PCT/CN2021/091536
Authority: WO
Inventors: 谢晗; 刘彬彬; 李明
Original assignee: 江西晶超光学有限公司
Priority date: 2021-04-30
Filing date: 2021-04-30
Publication date: 2022-11-03

Abstract

An optical system, a lens module, and an electronic device. The optical system sequentially comprises, from an object side to an image side in an optical axis direction: a first lens (L1) having a negative refractive power; a second lens (L2) having a positive refractive power; a third lens (L3) having a negative refractive power; a fourth lens (L4) having a positive refractive power; a fifth lens (L5) having a negative refractive power; and the optical system satisfies the conditional expression: 0.5 < D1/ImgH < 0.73, wherein D1 is an optical effective radius of an object-side surface (S1) of the first lens (L1), and ImgH is half of the image height corresponding to the maximum field angle of the optical system. The five-sheet optical system having the structure can simultaneously meet the requirements of a larger field angle and high imaging quality.

Description

Optical systems, lens modules and electronics

technical field

The invention belongs to the technical field of optical imaging, and in particular relates to an optical system, a lens module and an electronic device.

Background technique

Today, with the rapid development of technology, consumers have higher and higher requirements for imaging quality of mobile electronic products. In order to meet high-end imaging systems and achieve wide-angle shooting effects, the five-piece lens can be used as one of the accessories for various types of camera-capable portable electronic devices. However, the existing five-piece lens cannot meet the requirements of a large field of view and high imaging quality at the same time.

SUMMARY OF THE INVENTION

The purpose of this application is to provide an optical system, a lens module and an electronic device for solving the above technical problems.

The present invention provides an optical system, comprising in sequence from the object side to the image side along the optical axis direction: a first lens with negative refractive power, the object side of the first lens is convex at the near optical axis, and the image side is near the optical axis. The optical axis is concave; the second lens has positive refractive power; the object side of the second lens is convex at the near optical axis, and the image side is convex at the near optical axis; the third lens has negative refractive power, The image side of the third lens is concave at the near optical axis; the fourth lens has positive refractive power; the object side of the fourth lens is concave at the near optical axis, and the image side is convex at the near optical axis The fifth lens has negative refractive power; the object side of the fifth lens is convex at the near optical axis, and the image side is concave at the near optical axis; the optical system satisfies the conditional formula: 0.5<D1/ImgH< 0.73, wherein D1 is the optical effective radius of the object side of the first lens, and ImgH is half of the image height corresponding to the maximum angle of view of the optical system. In this application, the first lens and the third lens have strong negative refractive power, so as to diverge the light entering the optical system from the object side, which is beneficial to increase the field angle of the optical system; the second lens has a strong positive refractive power The force and the biconvex design of the object side and the image side produce strong positive refractive power, which can well correct the aberration generated by the first lens, and is conducive to shortening the total length; the fifth lens with negative refractive power can easily ensure the back focus; The positive and negative and concave-convex matching of the lens is conducive to shortening the total length of the optical system, realizing a miniaturized design, and also helping the light to better converge on the imaging surface of the optical system. When the optical system satisfies the above conditional formula, the size of the effective aperture on the object side of the first lens of the optical system is optimized, which can satisfy the good imaging quality and at the same time expand the field of view, so that more light can be incident on the optical system . When D1/ImgH≤0.5, the aperture of the first lens is too small. When matched with a large-sized and high-pixel chip, the field of view is limited to a small size, which is not conducive to capturing images with a large viewing angle. When D1/ImgH≥0.73, the image size is small. , the image resolution is insufficient, it is difficult to meet the high pixel requirements, and the aperture of the first lens is too large and not fully compressed, resulting in a large-scale lens module, which is difficult to meet the requirements of small electronic equipment.

In some possible embodiments, the second lens is made of glass, and the optical system satisfies the conditional formula: 2.9<f/CT2<6.7, where f is the focal length of the optical system, and CT2 is the first The thickness of the two lenses on the optical axis. When the optical system satisfies the above conditional formula, the thickness of the second lens can be reasonably controlled, and in different environments, the performance of the second lens will show a small temperature drift change. At the same time, the second lens is made of glass material, and the focal length control of the entire lens is more stable than that of plastic lenses, which can solve the problem of image distortion that may be caused by temperature difference changes. Glass material is more stable than plastic material under different temperature changes. The change is small, and the glass lens with high refractive index is used to optimize the modulation transfer function of the lens, improve the resolution of the lens, and ensure the high pixel of the optical system while expanding the field of view, so that the object can be photographed more comprehensively. The optical system of the present application can adopt a lens combination of glass lens and plastic lens, which has a better cost advantage than an all-glass lens group.

In some possible embodiments, the second lens is made of glass, and the optical system satisfies the conditional formula: 0.3<f2/TTL<0.5, where f2 is the focal length of the second lens, and TTL is the The distance from the object side of the first lens to the imaging plane of the optical system on the optical axis. The second lens has a positive refractive power, is made of glass, and the temperature drift change is small. The focal length control of the entire lens is more stable than that of the plastic lens, which can solve the problem of image distortion that may be caused by the temperature difference. Compared with plastic materials, the performance is more stable, the focal length change is small, and the glass lens with high refractive index is used to optimize the modulation transfer function of the lens, improve the resolution of the lens, and ensure high pixels of the optical system while expanding the field of view. shooting object. When the optical system satisfies the above conditional formula, the total length of the optical system is too suitable, the thickness of the glass lens is suitable, the processing difficulty is small, the focal length of the second lens is suitable, the refractive power is suitable, and the aberration correction is easy. When f2/TTL≥0.5, the total length of the optical system is excessively compressed, the thickness of the glass lens is too thin, and the processing difficulty increases, which is not conducive to the stability of mass production; when f2/TTL≤0.3, the total length of the optical system is not compressed enough, and the second The focal length of the lens is short, the refractive power is large, and aberration correction becomes difficult.

In some possible embodiments, the optical system satisfies the conditional formula: 0.27<tanω/FNO<0.33, where ω is half of the maximum angle of view of the optical system, and FNO is the aperture number of the optical system. When the optical system satisfies the above conditional formula, the light transmission amount of the optical system can be reasonably controlled, which is beneficial to increase the field of view of the optical system and meet the requirements of wide-angle. If tanω/FNO≥0.33, the FNO is too small, the aperture is too large, and it becomes difficult to correct aberrations with the five-piece optical system; if tanω/FNO≤0.27, the field of view is too small, which is not conducive to expanding the image range.

In some possible embodiments, the optical system satisfies the conditional formula: -10<f1/R2<-2, where f1 is the focal length of the first lens, and R2 is the distance between the image side of the first lens and the light The radius of curvature at the axis. When the optical system satisfies the above conditional expression, the first lens provides negative refractive power, so that light with a large viewing angle enters the optical system, and the first image side is convex, which is conducive to the convergence of light. If f1/R2≤-10, the radius of curvature of the image side of the first lens is small, the curvature is large, and the molding process is poor. If f1/R2≥-2, the refractive power of the first lens is too large, the light deflection angle is too large, and the system is sensitive , which is not conducive to maintaining high resolution.

In some possible embodiments, the optical system satisfies the conditional formula: 0.7<ET1/CT1<1.0, wherein CT1 is the thickness of the first lens on the optical axis, and ET1 is the object of the first lens The distance from the side surface at the maximum optical effective diameter to the image side surface of the first lens at the maximum optical effective diameter on the optical axis. When the optical system satisfies the above conditional expression, the ratio of ET1/CT1 is optimized, so that the thickness ratio of the first lens is within the range of easy processing and molding.

In some possible embodiments, the optical system satisfies the conditional formula: 0.01<|f12/f345|<0.5, where f12 is the composite focal length of the first lens and the second lens, and f345 is the The combined focal length of the third lens, the fourth lens, and the fifth lens. When the optical system satisfies the above conditional expression, the first lens and the second lens control the effective focal length of the lens, thereby limiting the total length of the entire optical system, the third lens, the fourth lens and the fifth lens cooperate with the second lens to correct chromatic aberration, The first lens collects light, and the second lens provides a strong positive refractive power. Adjusting the refractive power and shape of the first lens and the second lens can make the light better enter the optical system. While shortening the overall length of the optical system, Guarantee good image quality.

In some possible embodiments, the optical system satisfies the conditional formula: 0.68<f2/f<0.91, where f2 is the focal length of the second lens, and f is the focal length of the optical system. When the optical system satisfies the above conditional expression, by reasonably configuring the ratio of f2/f, the aberration and field curvature of the optical system can be corrected, and the focal length of the optical system can be adjusted.

In some possible embodiments, the optical system satisfies the conditional formula: 7.0<TTL/BFL≤9.3, 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 BFL is The shortest distance from the image side surface of the fifth lens to the imaging surface of the optical system in a direction parallel to the optical axis. When the optical system satisfies the above conditional expression, the total length of the optical system is suitable, which is conducive to the optimization of the lens surface shape, the back focal length is suitable, and the chief ray incident angle (CRA) of the optical system can be easily matched to the chip. When TTL/BFL≤7.0, the total length of the optical system is excessively compressed, which is not conducive to the optimization of the lens surface; when TTL/BFL>9.3, the back focal length is compressed too short, and it becomes difficult to match the CRA chip.

In some possible embodiments, the optical system satisfies the conditional formula: 1.3<(R7+R8)/(R7-R8)<2.6, where R7 is the curvature of the object side of the fourth lens at the optical axis Radius, R8 is the curvature radius of the image side surface of the fourth lens at the optical axis. When the optical system satisfies the above conditional expression, the fourth lens provides positive refractive power. By optimizing the shape of the fourth lens, the aberration of the peripheral field of view can be better corrected, the image of the peripheral field of view can be improved, and it is conducive to lightening Peripheral reflection ghost image.

The present invention provides a lens module, comprising a lens barrel, an electronic photosensitive element and the above-mentioned optical system, wherein the optical system is arranged in the lens barrel, and the electronic photosensitive element is arranged on the image side of the optical system. The electronic photosensitive element is disposed on the image side of the optical system, and is used for converting the light rays of objects incident on the electronic photosensitive element through the first lens to the fifth lens into electrical signals of an image. In the present application, the first lens to the fifth lens of the optical system are installed in the lens module to diverge the light entering the optical system from the object side, which is conducive to increasing the field of view of the optical system and shortening the total length of the optical system. , to achieve a miniaturized design, and at the same time, it is also beneficial for the light to be better concentrated on the imaging surface of the optical system.

The present invention provides an electronic device, comprising a casing and the above-mentioned lens module, wherein the lens module is arranged in the casing. In the present application, by arranging the above-mentioned lens module in the electronic equipment, the light entering the optical system from the object side is diffused, which is conducive to increasing the field of view of the optical system, shortening the overall length, and realizing a miniaturized design. It is beneficial for the light to be better concentrated on the imaging surface of the optical system.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1a is a schematic structural diagram of an optical system of the first embodiment;

Fig. 1b is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the first embodiment;

2a is a schematic structural diagram of an optical system of a second embodiment;

Fig. 2b is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the second embodiment;

3a is a schematic structural diagram of an optical system of a third embodiment;

Fig. 3b is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the third embodiment;

4a is a schematic structural diagram of an optical system of a fourth embodiment;

Fig. 4b is the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the fourth embodiment;

Fig. 5a is the structural schematic diagram of the optical system of the fifth embodiment;

Fig. 5b is a longitudinal spherical aberration curve, astigmatism curve and distortion curve of the fifth embodiment.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to 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, but not all of 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.

An embodiment of the present application provides a lens module, the lens 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 fifth lens of the optical system are installed in the lens barrel. The electronic photosensitive element is disposed on the image side of the optical system, and is used for converting 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 may be a complementary metal oxide semiconductor (Complementary Metal Oxide Semiconductor, CMOS) or a charge-coupled device (Charge-coupled Device, CCD). The lens module can be an independent lens of a digital camera, or an imaging module integrated on an electronic device such as a smart phone. In the present application, by installing the first lens to the fifth lens of the optical system in the lens module, and rationally configuring the surface shape and refractive power of each lens of the first lens to the fifth lens, the optical system of five lenses can be made at the same time. Meet the requirements of larger field of view and miniaturization.

The embodiments of the present application provide an electronic device, and the electronic device includes a housing and the lens module provided by the embodiments of the present application. The lens module and the electronic photosensitive element are arranged in the casing. The electronic device may be a smart phone, a smart home appliance, a robot, a personal digital assistant (PDA), a tablet computer, a smart watch, a drone, an electronic book reader, a driving recorder, a wearable device, and the like. In the present application, by arranging a lens module in an electronic device, the electronic device can meet the requirements of a larger field of view and miniaturization at the same time.

An embodiment of the present application provides an optical system, which includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens in sequence from the object side to the image side along the optical axis direction. In the first to fifth lenses, any two adjacent lenses may have an air space between them.

Specifically, the specific shapes and structures of the five lenses are as follows:

The first lens has a negative refractive power, the object side of the first lens is convex at the near-optical axis, and the image side is concave at the near-optical axis; the second lens has a positive refractive power; the second lens has a The object side is convex at the near optical axis, and the image side is convex at the near optical axis; the third lens has a negative refractive power, and the image side of the third lens is concave at the near optical axis; the fourth lens has a positive refractive power; the object side of the fourth lens is concave at the near optical axis, and the image side is convex at the near optical axis; the fifth lens has a negative refractive power; the object side of the fifth lens is at the low beam The axis is convex, and the image side is concave at the near optical axis; the optical system satisfies the conditional formula: 0.5<D1/ImgH<0.73, where D1 is the optical effective radius of the object side of the first lens, and ImgH is the half of the image height corresponding to the maximum angle of view of the optical system. In this application, the first lens and the third lens have strong negative refractive power, so as to diverge the light entering the optical system from the object side, which is beneficial to increase the field angle of the optical system; the second lens has a strong positive refractive power The force and the biconvex design of the object side and the image side produce strong positive refractive power, which can well correct the aberration generated by the first lens, and is conducive to shortening the total length; the fifth lens with negative refractive power can easily ensure the back focus; The positive and negative and concave-convex matching of the lens is conducive to shortening the total length of the optical system, realizing a miniaturized design, and also helping the light to better converge on the imaging surface of the optical system. When the optical system satisfies the above conditional formula, the size of the effective aperture on the object side of the first lens of the optical system is optimized, which can satisfy the good imaging quality and at the same time expand the field of view, so that more light can be incident on the optical system . When D1/ImgH≤0.5, the aperture of the first lens is too small. When matched with a large-sized and high-pixel chip, the field of view is limited to a small size, which is not conducive to capturing images with a large viewing angle. When D1/ImgH≥0.73, the image size is small. , the image resolution is insufficient, it is difficult to meet the high pixel requirements, and the aperture of the first lens is too large and not fully compressed, resulting in a large-scale lens module, which is difficult to meet the requirements of small electronic equipment.

In a specific embodiment, the second lens is made of glass, and the optical system satisfies the conditional formula: 2.9<f/CT2<6.7, where f is the focal length of the optical system, and CT2 is the second The thickness of the lens on the optical axis. When the optical system satisfies the above conditional formula, the thickness of the second lens can be reasonably controlled, and under different environments, the performance of the second lens will show a small temperature drift change. At the same time, the second lens is made of glass material, and the focal length control of the entire lens is more stable than that of plastic lenses, which can solve the problem of image distortion that may be caused by temperature difference changes. Glass material is more stable than plastic material under different temperature changes. The change is small, and the glass lens with high refractive index is used to optimize the modulation transfer function of the lens, improve the resolution of the lens, and ensure the high pixel of the optical system while expanding the field of view, so that the object can be photographed more comprehensively. The optical system of the present application can adopt a lens combination of glass lens and plastic lens, which has a better cost advantage than an all-glass lens group.

In a specific embodiment, the second lens is made of glass, and the optical system satisfies the conditional formula: 0.3<f2/TTL<0.5, where f2 is the focal length of the second lens, and TTL is the first The distance from the object side of a lens to the imaging plane of the optical system on the optical axis. The second lens has a positive refractive power, is made of glass, and the temperature drift change is small. The focal length control of the entire lens is more stable than that of the plastic lens, which can solve the problem of image distortion that may be caused by the temperature difference. Compared with plastic materials, the performance is more stable, the focal length change is small, and the glass lens with high refractive index is used to optimize the modulation transfer function of the lens, improve the resolution of the lens, and ensure high pixels of the optical system while expanding the field of view. shooting object. When the optical system satisfies the above conditional formula, the total length of the optical system is too suitable, the thickness of the glass lens is suitable, the processing difficulty is small, the focal length of the second lens is suitable, the refractive power is suitable, and the aberration correction is easy. When f2/TTL≥0.5, the total length of the optical system is excessively compressed, the thickness of the glass lens is too thin, and the processing difficulty increases, which is not conducive to the stability of mass production; when f2/TTL≤0.3, the total length of the optical system is not compressed enough, and the second The focal length of the lens is short, the refractive power is large, and aberration correction becomes difficult.

In a specific embodiment, the optical system satisfies the conditional formula: 0.27<tanω/FNO<0.33, where ω is half of the maximum field angle of the optical system, and FNO is the aperture number of the optical system. When the optical system satisfies the above conditional formula, the light transmission amount of the optical system can be reasonably controlled, which is beneficial to increase the field of view of the optical system and meet the requirements of wide-angle. If tanω/FNO≥0.33, the FNO is too small, the aperture is too large, and it becomes difficult to correct aberrations with the five-piece optical system; if tanω/FNO≤0.27, the field of view is too small, which is not conducive to expanding the image range.

In a specific embodiment, the optical system satisfies the conditional formula: -10<f1/R2<-2, where f1 is the focal length of the first lens, and R2 is the image side of the first lens on the optical axis The radius of curvature at . When the optical system satisfies the above conditional expression, the first lens provides negative refractive power, so that light with a large viewing angle enters the optical system, and the first image side is convex, which is conducive to the convergence of light. If f1/R2≤-10, the radius of curvature of the image side of the first lens is small, the curvature is large, and the molding process is poor. If f1/R2≥-2, the refractive power of the first lens is too large, the light deflection angle is too large, and the system is sensitive , which is not conducive to maintaining high resolution.

In a specific embodiment, the optical system satisfies the conditional formula: 0.7<ET1/CT1<1.0, wherein CT1 is the thickness of the first lens on the optical axis, and ET1 is the object side surface of the first lens The distance from the maximum optical effective diameter to the image side surface of the first lens where the maximum optical effective diameter is on the optical axis. When the optical system satisfies the above conditional expression, the ratio of ET1/CT1 is optimized, so that the thickness ratio of the first lens is within the range of easy processing and molding.

In a specific embodiment, the optical system satisfies the conditional formula: 0.01<|f12/f345|<0.5, where f12 is the combined focal length of the first lens and the second lens, and f345 is the third lens , the composite focal length of the fourth lens and the fifth lens. When the optical system satisfies the above conditional expression, the first lens and the second lens control the effective focal length of the lens, thereby limiting the total length of the entire optical system, the third lens, the fourth lens and the fifth lens cooperate with the second lens to correct chromatic aberration, The first lens collects light, and the second lens provides a strong positive refractive power. Adjusting the refractive power and shape of the first lens and the second lens can make the light better enter the optical system. While shortening the overall length of the optical system, Guarantee good image quality.

In a specific embodiment, the optical system satisfies the conditional formula: 0.68<f2/f<0.91, where f2 is the focal length of the second lens, and f is the focal length of the optical system. When the optical system satisfies the above conditional expression, by reasonably configuring the ratio of f2/f, the aberration and field curvature of the optical system can be corrected, and the focal length of the optical system can be adjusted.

In a specific embodiment, the optical system satisfies the conditional formula: 7.0<TTL/BFL≤9.3, 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 BFL is the The shortest distance from the image side surface of the fifth lens to the imaging surface of the optical system in the direction parallel to the optical axis. When the optical system satisfies the above conditional expression, the total length of the optical system is suitable, which is conducive to the optimization of the lens surface shape, the back focal length is suitable, and the chief ray incident angle (CRA) of the optical system can be easily matched to the chip. When TTL/BFL≤7.0, the total length of the optical system is excessively compressed, which is not conducive to the optimization of the lens surface; when TTL/BFL>9.3, the back focal length is compressed too short, and it becomes difficult to match the CRA chip.

In a specific embodiment, the optical system satisfies the conditional formula: 1.3<(R7+R8)/(R7-R8)<2.6, where R7 is the radius of curvature of the object side of the fourth lens at the optical axis , R8 is the radius of curvature of the image side surface of the fourth lens at the optical axis. When the optical system satisfies the above conditional expression, the fourth lens provides positive refractive power. By optimizing the shape of the fourth lens, the aberration of the peripheral field of view can be better corrected, the image of the peripheral field of view can be improved, and it is conducive to lightening Peripheral reflection ghost image.

The first embodiment,

Please refer to FIG. 1a and FIG. 1b. The optical system of this embodiment includes sequentially from the object side to the image side along the optical axis direction:

The first lens L1 has a negative bending force, the object side S1 of the first lens L1 is convex at the near optical axis, and the image side S2 is concave at the near optical axis; the object side S1 of the first lens L1 is convex at the circumference. , like the side surface S2 is concave at the circumference.

The second lens L2 has a positive refracting power, the object side S3 of the second lens L2 is convex at the near optical axis, and the image side S4 is convex at the near optical axis; the object side S3 of the second lens L2 is convex at the circumference , like the side S4 is convex at the circumference.

The third lens L3 has a negative bending force, the object side S5 of the third lens L3 is convex at the near optical axis, and the image side S6 is concave at the near optical axis; the object side S5 of the third lens L3 is convex at the circumference , like the side surface S6 is concave at the circumference.

The fourth lens L4 has a positive refracting power, the object side S7 of the fourth lens is concave at the near optical axis, and the image side S8 is convex at the near optical axis; the object side S7 of the fourth lens L4 is concave at the circumference, The image side S8 is convex at the circumference.

The fifth lens L5 has a negative bending force, the object side S9 of the fifth lens L5 is convex at the near optical axis, and the image side S10 is concave at the near optical axis; the object side S9 of the fifth lens L5 is concave at the circumference , like the side S10 is convex at the circumference.

In addition, the optical system also includes a diaphragm STO, an infrared filter L6 and an image plane S13. The diaphragm STO is disposed between the first lens L1 and the second lens L2 for controlling the amount of incoming light. In other embodiments, the stop STO may also be disposed on other lenses, or between the other two lenses. The infrared filter L6 is arranged on the image side of the fifth lens L5, which includes the object side S11 and the image side S12, and the infrared filter L6 is used to filter out infrared light, so that the light entering the image surface S13 is visible light, visible light The wavelength is 380nm-780nm. The material of the infrared filter L6 is glass, and can be coated on the glass. The image plane S13 is the plane where the image formed by the light of the object passing through the optical system is located.

Table 1a shows a table of characteristics of the optical system of the present embodiment, and the reference wavelength of the refractive index, Abbe number, and focal length of each lens in the table is all 587.56 nm. Y radius, thickness, and focal length are in millimeters (mm).

Table 1a

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

In this embodiment, the object side and the image side of any one of the first lens L1, the third lens L3, the fourth lens L4, and the fifth lens L5 are aspherical, and the surface type x of each aspherical lens can be used But not limited to the following aspheric formulas:

Among them, x is the distance vector height of the aspheric surface from the vertex of the aspheric surface when the height is h along the optical axis; c is the paraxial curvature of the aspheric surface, c=1/R (that is, the paraxial curvature c is the above table The reciprocal of the Y radius R in 1a); k is the conic coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 1b gives the coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of higher order terms that can be used for each of the aspheric mirror surfaces S1-S13 in the first embodiment.

Table 1b

FIG. 1b shows longitudinal spherical aberration curves, astigmatism curves and distortion curves of the optical system of the first embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the focusing point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the curvature of the sagittal image plane; the distortion curve represents the magnitude of distortion corresponding to different field angles . According to the longitudinal spherical aberration diagram in Figure 1b, the longitudinal spherical aberration generated by the optical system for light with wavelengths of 486.1327nm, 587.5618nm, and 656.2725nm is between -0.02mm and 0.02mm; according to the astigmatism diagram in Figure 1b, the optical The astigmatism of the system to the light with a wavelength of 587.5618nm in the meridional and sagittal directions is between -0.1mm and 0.1mm; according to the distortion diagram in Figure 1b, it can be seen that the distortion of the optical system to the light of 587.5618nm is between -3.0 % to 3.0%. It can be seen from FIG. 1b that the optical system provided in the first embodiment can achieve good imaging quality.

The second embodiment,

Please refer to FIG. 2a and FIG. 2b. The optical system of this embodiment includes sequentially from the object side to the image side along the optical axis direction:

The fourth lens L4 has a positive refracting power, the object side S7 of the fourth lens L4 is concave at the near optical axis, and the image side S8 is convex at the near optical axis; the object side S7 of the fourth lens L4 is concave at the circumference , like the side surface S8 is convex at the circumference.

Other structures of the second embodiment are the same as those of the first embodiment, which can be referred to.

Table 2a shows a table of characteristics of the optical system of the present embodiment, and the reference wavelength of the refractive index, Abbe number, and focal length of each lens in the table is all 587.56 nm. Y radius, thickness, and focal length are in millimeters (mm).

Table 2a

Wherein, the meanings of the parameters in Table 2a are the same as the meanings of the parameters in the first embodiment.

Table 2b shows the coefficients of higher-order terms that can be used for each aspherical mirror surface in the second embodiment, wherein each aspherical surface type can be defined by the formula given in the first embodiment.

Table 2b

FIG. 2b shows longitudinal spherical aberration curves, astigmatism curves and distortion curves of the optical system of the second embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the focusing point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the curvature of the sagittal image plane; the distortion curve represents the magnitude of distortion corresponding to different field angles . According to the longitudinal spherical aberration diagram in Figure 2b, the longitudinal spherical aberration generated by the optical system for light with wavelengths of 486.1327nm, 587.5618nm, and 656.2725nm is between -0.02mm and 0.02mm; according to the astigmatism diagram in Figure 2b, the optical The astigmatism of the system to the light with a wavelength of 587.5618nm in the meridional and sagittal directions is between -0.1mm and 0.1mm; according to the distortion diagram in Figure 2b, it can be seen that the distortion of the optical system to the light of 587.5618nm is between 0% to 3.0%. It can be seen from FIG. 2b that the optical system provided in the second embodiment can achieve good imaging quality.

The third embodiment,

Please refer to FIG. 3a and FIG. 3b. The optical system of this embodiment includes sequentially from the object side to the image side along the optical axis direction:

The third lens L3 has a negative bending force, the object side S1 of the third lens L3 is convex at the near optical axis, the image side S2 is concave at the near optical axis; the object side S5 of the third lens L3 is concave at the circumference , like the side S6 is convex at the circumference.

The fourth lens L4 has a positive refracting power, the object side S7 of the fourth lens L4 is concave at the near optical axis, and the image side S8 is convex at the near optical axis; the object side S7 of the fourth lens L4 is convex at the circumference , like the side surface S8 is convex at the circumference.

Other structures of the third embodiment are the same as those of the first embodiment, which can be referred to.

Table 3a shows a table of characteristics of the optical system of the present embodiment, and the reference wavelength of the refractive index, Abbe number, and focal length of each lens in the table is all 587.56 nm. Y radius, thickness, and focal length are in millimeters (mm).

Table 3a

Wherein, the meanings of the parameters in Table 3a are the same as the meanings of the parameters in the first embodiment.

Table 3b shows the coefficients of higher-order terms that can be used for each aspherical mirror surface in the third embodiment, wherein each aspherical surface type can be defined by the formula given in the first embodiment.

Table 3b

FIG. 3b shows longitudinal spherical aberration curves, astigmatism curves and distortion curves of the optical system of the third embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the focusing point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the curvature of the sagittal image plane; the distortion curve represents the magnitude of distortion corresponding to different field angles . According to the longitudinal spherical aberration diagram in Fig. 3b, the longitudinal spherical aberration generated by the optical system for light with wavelengths of 486.1327 nm, 587.5618 nm, and 656.2725 nm is between -0.02 mm and 0.02 mm; The astigmatism of the system to the light with a wavelength of 587.5618nm in the meridional and sagittal directions is between -0.1mm and 0.1mm; according to the distortion diagram in Figure 3b, it can be seen that the distortion of the optical system to the light of 587.5618nm is between -2.5 % to 5.0%. It can be seen from FIG. 3b that the optical system provided in the third embodiment can achieve good imaging quality.

Fourth embodiment,

Referring to FIG. 4a and FIG. 4b, the optical system of the present embodiment includes sequentially from the object side to the image side along the optical axis direction:

The third lens L3 has a negative bending force, the object side S1 of the third lens L3 is concave at the near optical axis, the image side S2 is concave at the near optical axis; the object side S5 of the third lens L3 is concave at the circumference , like the side surface S6 is concave at the circumference.

Other structures of the fourth embodiment are the same as those of the first embodiment, and can be referred to.

Table 4a shows a table of characteristics of the optical system of this embodiment, and the reference wavelength of the refractive index, Abbe number, and focal length of each lens in the table is all 587.56 nm. Y radius, thickness, and focal length are in millimeters (mm).

Table 4a

Wherein, the meanings of the parameters in Table 4a are the same as the meanings of the parameters in the first embodiment.

Table 4b shows the coefficients of higher-order terms that can be used for each aspherical mirror surface in the fourth embodiment, wherein each aspherical surface type can be defined by the formula given in the first embodiment.

Table 4b

FIG. 4b shows longitudinal spherical aberration curves, astigmatism curves and distortion curves of the optical system of the fourth embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the focusing point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the curvature of the sagittal image plane; the distortion curve represents the magnitude of distortion corresponding to different field angles . According to the longitudinal spherical aberration diagram in Figure 4b, the longitudinal spherical aberration generated by the optical system for light with wavelengths of 486.1327nm, 587.5618nm, and 656.2725nm is between -0.004mm and 0.008mm; according to the astigmatism diagram in Figure 4b, the optical The astigmatism of the system to the light with a wavelength of 587.5618nm in the meridional and sagittal directions is between -0.1mm and 0.1mm; according to the distortion diagram in Figure 4b, it can be seen that the distortion of the optical system to the light of 587.5618nm is between 0% to 2.5%. It can be seen from FIG. 4b that the optical system provided in the fourth embodiment can achieve good imaging quality.

The fifth embodiment,

Please refer to FIG. 5a and FIG. 5b , the optical system of this embodiment includes sequentially from the object side to the image side along the optical axis direction:

The other structures of the fifth embodiment are the same as those of the first embodiment, which can be referred to.

Table 5a shows a table of characteristics of the optical system of the present embodiment, and the reference wavelength of the refractive index, Abbe number, and focal length of each lens in the table is all 587.56 nm. Y radius, thickness, and focal length are in millimeters (mm).

Table 5a

Wherein, the meanings of the parameters in Table 5a are the same as the meanings of the parameters in the first embodiment.

Table 5b shows the coefficients of higher-order terms that can be used for each aspherical mirror surface in the fifth embodiment, wherein each aspherical surface type can be defined by the formula given in the first embodiment.

Table 5b

FIG. 5b shows longitudinal spherical aberration curves, astigmatism curves and distortion curves of the optical system of the fifth embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the focusing point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the curvature of the sagittal image plane; the distortion curve represents the magnitude of distortion corresponding to different field angles . According to the longitudinal spherical aberration diagram in Figure 5b, the longitudinal spherical aberration generated by the optical system for light with wavelengths of 486.1327nm, 587.5618nm, and 656.2725nm is between -0.01mm and 0.02mm; according to the astigmatism diagram in Figure 5b, the optical The astigmatism of the system to the light with a wavelength of 587.5618nm in the meridional and sagittal directions is between -0.1mm and 0.1mm; according to the distortion diagram in Figure 5b, it can be seen that the distortion of the optical system to the light of 587.5618nm is between 0% to 2.5%. It can be seen from FIG. 5b that the optical system provided in the fifth embodiment can achieve good imaging quality.

Table 6 shows D1/ImgH, f/CT2, f2/TTL, tanω/FNO, f1/R2, ET1/CT1, 0.01<|f12/f345|<0.5, Values of f2/f, TTL/BFL, (R7+R8)/(R7-R8).

Table 6

	D1/ImgHD1/ImgH	f/CT2f/CT2	f2/TTLf2/TTL	tanω/FNOtanω/FNO	f1/R2f1/R2
第一实施例first embodiment	0.7230.723	6.6236.623	0.4800.480	0.3000.300	-4.8-4.8
第二实施例Second Embodiment	0.5060.506	3.5823.582	0.4030.403	0.2790.279	-7.7-7.7
第三实施例Third Embodiment	0.5370.537	4.0744.074	0.3940.394	0.3090.309	-2.1-2.1
第四实施例Fourth Embodiment	0.4900.490	3.7073.707	0.3600.360	0.2790.279	-9.0-9.0
第五实施例Fifth Embodiment	0.5310.531	2.9322.932	0.3800.380	0.3250.325	-6.4-6.4
	ET1/CT1ET1/CT1	0.01<\|f12/f345\|<0.50.01<\|f12/f345\|<0.5	f2/ff2/f	TTL/BFLTTL/BFL	(R7+R8)/(R7-R8)(R7+R8)/(R7-R8)
第一实施例first embodiment	0.9180.918	0.3070.307	0.9080.908	7.5007.500	1.3041.304
第二实施例Second Embodiment	0.7780.778	0.0170.017	0.7690.769	7.8697.869	1.3631.363
第三实施例Third Embodiment	0.9850.985	0.4230.423	0.7970.797	8.2178.217	1.5811.581
第四实施例Fourth Embodiment	0.7450.745	0.1860.186	0.6830.683	7.8697.869	1.5571.557
第五实施例Fifth Embodiment	0.8250.825	0.3430.343	0.6980.698	9.3009.300	2.5192.519

It can be seen from Table 6 that each embodiment satisfies the following conditional formulas: 0.5<D1/ImgH<0.73, 2.9<f/CT2<6.7, 0.3<f2/TTL<0.5, 0.27<tanω/FNO<0.33, -10<f1/ R2<-2, 0.7<ET1/CT1<1.0, 0.01<|f12/f345|<0.5, 0.68<f2/f<0.91, 7.0<TTL/BFL≤9.3, 1.3<(R7+R8)/(R7- R8) < 2.6.

In some embodiments, the present invention also provides a lens module, which is applied to a mobile camera device of an unmanned aerial vehicle. In the present application, the first lens to the fifth lens of the optical system are installed in the lens module to diverge the light entering the optical system from the object side, which is conducive to increasing the field of view of the optical system and shortening the total length of the optical system. , to achieve a miniaturized design, and at the same time, it is also beneficial for the light to be better concentrated on the imaging surface of the optical system.

The present invention also provides an electronic device in some embodiments. The electronic device may be, but is not limited to, a portable phone, a video phone, a smart phone, an electronic book reader, a drone, a driving recorder, or other in-vehicle camera equipment, or a wearable device such as a smart watch. The following will take the electronic device as the drone as an example. The electronic device includes the above-mentioned lens module. The first lens and the third lens have strong negative refractive power, so as to diverge the light entering the optical system from the object side, which is beneficial to increase the field angle of the optical system; the second lens has strong positive refractive power and the object side The biconvex design on the side of the image and the image produces a strong positive refractive power, which can well correct the aberration caused by the first lens, and is conducive to shortening the overall length; the fifth lens with negative refractive power can easily ensure the back focus; The concave-convex collocation is conducive to shortening the total length of the optical system, realizing a miniaturized design, and also helping the light to better converge on the imaging surface of the optical system. The size of the effective aperture on the object side of the first lens of the optical system is optimized, which can satisfy the good imaging quality and at the same time expand the field of view, so that more light can be incident on the optical system. Compared with the general wide-angle lens, the first lens of the common wide-angle lens has a large diameter, which is not conducive to being placed in a small drone. The present application optimizes the aperture, surface curvature, shape, etc. of the first lens while expanding the viewing angle range, so as to reduce the aperture, which is more conducive to the design of the miniaturized head. At the same time, the second lens is made of glass material, and the focal length control of the entire lens is more stable than that of plastic lenses, which can solve the problem of image distortion that may be caused by temperature difference changes. Glass material is more stable than plastic material under different temperature changes. The change is small, and the glass lens with high refractive index is used to optimize the modulation transfer function of the lens, improve the resolution of the lens, and ensure the high pixel of the optical system while expanding the field of view, so that the object can be photographed more comprehensively. The optical system of the present application can adopt a lens combination of glass lens and plastic lens, which has a better cost advantage than an all-glass lens group.

The technical features of the above embodiments can be combined arbitrarily. For the sake of brief description, 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 that is the range described in this manual.

The above embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

An optical system, characterized in that, from the object side to the image side along the optical axis direction, it sequentially comprises:

The first lens has a negative refractive power, and the object side of the first lens is convex at the near-optical axis, and the image side is concave at the near-optical axis;

The second lens has a positive refractive power; the object side of the second lens is convex at the near-optical axis, and the image side is convex at the near-optical axis;

The third lens has a negative refractive power, and the image side of the third lens is concave at the near optical axis;

The fourth lens has a positive refractive power; the object side of the fourth lens is concave at the near-optical axis, and the image side is convex at the near-optical axis;

The fifth lens has a negative refractive power; the object side of the fifth lens is convex at the near-optical axis, and the image side is concave at the near-optical axis;

The optical system satisfies the conditional formula: 0.5<D1/ImgH<0.73, where D1 is the optical effective radius of the object side of the first lens, and ImgH is half of the image height corresponding to the maximum angle of view of the optical system .
The optical system according to claim 1, wherein the second lens is made of glass, and the optical system satisfies the conditional formula: 2.9<f/CT2<6.7, where f is the focal length of the optical system, CT2 is the thickness of the second lens on the optical axis.
The optical system according to claim 1, wherein the second lens is made of glass, and the optical system satisfies the conditional formula: 0.3<f2/TTL<0.5, wherein f2 is the focal length of the second lens , TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis.
The optical system according to claim 1, wherein the optical system satisfies the conditional formula: 0.27<tanω/FNO<0.33, wherein ω is half of the maximum field angle of the optical system, and FNO is the optical system The aperture number of the system.
The optical system according to claim 1, wherein the optical system satisfies the conditional formula: -10<f1/R2<-2, wherein f1 is the focal length of the first lens, and R2 is the first lens The radius of curvature of the image side of the lens at the optical axis.
The optical system according to claim 1, wherein the optical system satisfies the conditional formula: 0.7<ET1/CT1<1.0, wherein CT1 is the thickness of the first lens on the optical axis, and ET1 is the thickness of the first lens on the optical axis. The distance from the object side of the first lens at the maximum optical effective diameter to the image side of the first lens at the maximum optical effective diameter on the optical axis.
The optical system according to claim 1, wherein the optical system satisfies the conditional formula: 0.01<|f12/f345|<0.5, wherein f12 is the composite focal length of the first lens and the second lens , f345 is the combined focal length of the third lens, the fourth lens and the fifth lens.
The optical system according to claim 1, wherein the optical system satisfies the conditional formula: 0.68<f2/f<0.91, wherein f2 is the focal length of the second lens, and f is the focal length of the optical system .
The optical system according to claim 1, wherein the optical system satisfies the conditional formula: 7.0<TTL/BFL≤9.3, wherein, TTL is on the optical axis from the object side of the first lens to the imaging plane of the optical system BFL is the shortest distance from the image side of the fifth lens to the image plane of the optical system in a direction parallel to the optical axis.
The optical system according to claim 1, characterized in that, the optical system satisfies the conditional formula: 1.3<(R7+R8)/(R7-R8)<2.6, wherein R7 is the object side of the fourth lens at The curvature radius at the optical axis, R8 is the curvature radius of the image side surface of the fourth lens at the optical axis.
A lens module, characterized by comprising a lens barrel, an electronic photosensitive element and the optical system according to any one of claims 1 to 10, wherein the optical system is arranged in the lens barrel, and the electronic photosensitive element arranged on the image side of the optical system.
An electronic device is characterized by comprising a casing and the lens module according to claim 11 , wherein the lens module is arranged in the casing.