CN110351470B - Camera module - Google Patents

Abstract

The invention discloses a camera module, wherein: the lens module comprises a lens module, a shell, a bottom plate and a photosensitive chip; the mean square error radius of the focusing image point when the distance from the object point on the optical axis to the object principal surface of the lens module is smaller than 40mm is smaller than that when the object point on the optical axis is at infinity; the lens module sequentially comprises the following components from an object side to an image side along an optical axis: a first lens group, an aperture, a second lens group; the first lens group and the second lens group are both positive focal power; the object-side light-transmitting aperture of the first lens group is larger than the image Fang Tongguang aperture of the first lens group, and the object-side light-transmitting aperture of the second lens group is smaller than the image Fang Tongguang aperture of the second lens group; and specific technological parameters of the position relation between the lens module and the photosensitive surface of the photosensitive chip are given. This structure is favorable to reducing the distance of camera lens's image side terminal surface to sensitization chip when closely imaging, avoids adopting the increase apart from mode to realize closely photographing, does benefit to the miniaturization of structure.

Description

A camera module

Technical Field

The present invention belongs to the field of imaging, and specifically relates to a camera module, and in particular to a camera module for macro or microscopic imaging.

Background technique

Imaging devices are becoming more and more popular in our lives. Mobile phone cameras, computer cameras, driving recorders, surveillance cameras and other imaging devices appear in people's daily lives every day. Imaging is also increasingly moving towards miniaturization, and it can still maintain high imaging quality while miniaturization. In addition to the demand for taking photos of portraits, landscapes, etc., people also have the demand for taking photos of close-up objects. Taking mobile phones as an example, models with macro photography functions have appeared in recent years.

Existing macro cameras mostly use the method of increasing the image distance of the camera lens to achieve macro. Since general camera lenses are used for long-distance imaging, the imaging effect is not good in the case of macro. Even if the distance is increased, it can only increase the magnification but cannot obtain sufficient resolution.

Summary of the invention

In view of at least one of the above defects or improvement needs of the prior art, the present invention uses a unique lens design and determines the positional relationship between the lens and the photosensitive chip to construct a camera module, wherein the positional relationship between the lens and the photosensitive chip satisfies Formula 1. This structure is conducive to reducing the distance from the image side end face of the lens to the photosensitive chip during close-range imaging, avoiding the use of a distance increase method to achieve close-range photography, and is conducive to the miniaturization of the structure. At the same time, the lens includes a front lens group and a rear lens group, which are constructed into a structure of a compound microscope. At this time, the front lens group is equivalent to an objective lens, which can obtain excellent imaging quality.

To achieve the above object, according to one aspect of the present invention, a camera module is provided, which includes: a lens module, a housing, a base plate and a photosensitive chip;

The housing is used to fix the lens module and the base plate;

The photosensitive chip is mounted on the bottom plate;

The mean square error radius of the focused image point when the distance from the object point on the optical axis to the object principal surface of the lens module is less than 40 mm is smaller than the mean square error radius of the focused image point when the object point on the optical axis is located at infinity;

The lens module includes, from the object side to the image side of the optical axis, a first lens group, an aperture, and a second lens group;

The first lens group and the second lens group both have positive optical power; the object-side clear aperture of the first lens group is larger than the image-side clear aperture, and the object-side clear aperture of the second lens group is smaller than the image-side clear aperture;

The positional relationship between the lens module and the photosensitive surface of the photosensitive chip satisfies the following conditions:

0.5f ₂₀₀ <S _ima <1.5f ₂₀₀ (Formula 1);

Wherein _f200 is the focal length of the second lens group, that is, the distance from the image-side principal surface of the second lens group to the image-side focal plane of the second lens group, and _{Sima is} the distance from the photosensitive surface of the photosensitive chip to the image-side principal surface of the second lens group.

Preferably, the camera module further includes a filter;

The filter is installed on the object side of the photosensitive chip and fixed on the housing;

The position from the image-side principal surface of the second lens group to the image-side focal plane of the second lens group is the position after the refraction effect of the filter is taken into account.

Preferably, the camera module further includes a focus motor;

The focus motor is used to move the lens module relative to the housing, and within the focus range of the lens module, Formula 1 is valid.

Preferably, the focusing motor is a voice coil motor or an ultrasonic motor.

Preferably, the camera module further comprises a magnet, a front spring pad, a rear spring pad, and a coil;

The magnet and the coil constitute the focus motor;

The magnet is fixed to the inner wall of the housing, the front spring pad and the rear spring pad are used to limit the moving position of the lens module, and the coil is fixed to the outer wall of the lens module.

Preferably, the camera module does not have a focusing function, and the distance between the lens module and the photosensitive chip is a fixed value;

The camera modules of different specifications produce a series of different constants, but all satisfy Formula 1.

Preferably, when the camera module does not have a focusing function, the positional relationship between the lens module and the photosensitive surface of the photosensitive chip satisfies the following conditions:

_{Sima＝ f200} (Formula 2).

Preferably, the image-side medium of the first lens group and the object-side medium of the second lens group are air;

The aperture is located on the surface of the first lens group or the second lens group, or in the air medium on the object side or the image side thereof.

Preferably, the image-side medium of the first lens group and the object-side medium of the second lens group are made of transparent materials including plastic or glass;

In this case, the first lens group and the second lens group have a common lens, all lenses on the object side of the lens and the object side surface of the lens constitute the first lens group, and the image side surface of the lens and all lenses on the image side constitute the second lens group;

The aperture is located on the surface of the lens or in the transparent medium of the lens.

Preferably, the camera module is a camera module for a portable electronic product.

Preferably, the focal length f ₁₀₀ of the first lens group is ≤40 mm, and the focal length f ₂₀₀ of the second lens group is ≤20 mm;

When in use, the distance od ₁₀₀ between the object to be photographed and the object-side principal surface of the first lens group is less than 2 times the focal length of the first lens group 100, that is,

od ₁₀₀ <2f ₁₀₀ (Equation 1);

And the distance id ₂₀₀ from the image side principal surface to the image plane of the second lens group is less than twice the focal length of the second lens group, that is,

id ₂₀₀ <2f ₂₀₀ (relation 2);

The image-side numerical aperture NA _img100 of the first lens group and the object-side numerical aperture NA _obj200 of the second lens group satisfy the following conditions:

0<NA _img100 , NA _obj200 <0.05 (Equation 3).

Preferably, the distance _sd100 from the aperture to the edge of the first lens group along the optical axis direction satisfies the relationship:

sd ₁₀₀ <f ₁₀₀ (Equation 4);

The distance _sd200 from the aperture to the edge of the second lens group along the optical axis direction satisfies the relationship:

sd ₂₀₀ <f ₂₀₀ (Equation 5).

Preferably, the second lens group includes at least three lenses in sequence from the object side to the image side of the optical axis.

Preferably, the last two lenses of the second lens group arranged in sequence from the object side to the image side of the optical axis are arranged as follows:

The image-side surface of the penultimate lens is convex, and at least one of the object-side surface and the image-side surface is aspherical;

The object side surface and the image side surface of the last lens are both concave surfaces, and at least one of the object side surface and the image side surface is aspherical.

Preferably, the last two lenses of the second lens group arranged in sequence from the object side to the image side of the optical axis are arranged as follows:

The image-side surface of the penultimate lens is convex, and at least one of the object-side surface and the image-side surface is aspherical;

The object side surface of the last lens is convex, the image side surface is concave, at least one of the object side surface and the image side surface is aspherical, and has a region with the smallest central thickness and a greater thickness as it moves away from the axis.

Preferably, the last two lenses of the second lens group arranged in sequence from the object side to the image side of the optical axis are arranged as follows:

The object side surface of the penultimate lens is concave, the image side surface is convex, and at least one of the object side surface and the image side surface is aspherical;

The object side surface of the last lens is concave, the image side surface is convex, and at least one of the object side surface and the image side surface is aspherical.

Preferably, the last two lenses of the second lens group arranged in sequence from the object side to the image side of the optical axis are arranged as follows:

The image-side surface of the penultimate lens is convex, and at least one of the object-side surface and the image-side surface is aspherical;

The object side surface of the last lens is convex, the image side surface is concave, at least one of the object side surface and the image side surface is aspherical, and has a region with the largest central thickness and a decreasing thickness as it moves away from the axis.

Preferably, at least one of the object-side surface and the image-side surface of the last lens has an inflection point.

Preferably, the second lens group includes, in sequence from the object side to the image side along the optical axis:

The first lens has a convex object-side surface and an image-side surface;

The second lens has a concave object-side surface and an image-side surface;

The third lens has a convex surface at the center of the object side and then becomes concave at the off-axis periphery, and a concave surface at the center of the image side and then becomes convex at the off-axis periphery;

The image-side surface of the fourth lens is convex, and at least one of the object-side surface and the image-side surface is aspherical;

The object-side surface and the image-side surface of the fifth lens are both concave surfaces, and at least one of the object-side surface and the image-side surface is aspherical.

Preferably, the second lens group includes, in sequence from the object side to the image side along the optical axis:

The first lens has a convex object-side surface and an image-side surface;

The second lens has an object-side surface and an image-side surface both of which are concave surfaces, wherein the object-side surface is more concave than the image-side surface, and the image-side surface has an inflection point;

The third lens has an image-side surface that is convex, and at least one of its object-side surface and image-side surface that is aspherical;

The fourth lens has a convex object surface and a concave image surface. At least one of the object surface and the image surface is aspherical and has a region with the smallest central thickness and a greater thickness as it moves away from the axis.

Preferably, the second lens group includes, in sequence from the object side to the image side along the optical axis:

The first lens has a convex object-side surface and an image-side surface;

The second lens has a convex object surface and a concave image surface;

The third lens has a convex surface at the center of the object side and then becomes concave at the off-axis periphery, and a concave surface at the center of the image side and then becomes convex at the off-axis periphery;

The fourth lens has a concave object surface and a convex image surface;

a fifth lens having a concave object-side surface and a convex image-side surface, and at least one of the object-side surface and the image-side surface is aspherical;

The sixth lens has a concave object-side surface and a convex image-side surface, and at least one of the object-side surface and the image-side surface is an aspherical surface.

Preferably, the second lens group includes, in sequence from the object side to the image side along the optical axis:

The first lens has a convex object-side surface and an image-side surface;

The second lens has an image-side surface that is convex, and at least one of an object-side surface and an image-side surface that is aspherical;

The third lens has a convex object surface and a concave image surface. At least one of the object surface and the image surface is aspherical and has a region with the largest central thickness and a decreasing thickness as the thickness deviates from the axis.

Preferably, the first lens group includes at least three lenses in sequence from the object side to the image side of the optical axis.

Preferably, the first two lenses of the first lens group arranged in sequence from the object side to the image side of the optical axis are arranged as follows:

The object side surface and the image side surface of the first lens are both concave surfaces, and at least one of the object side surface and the image side surface is aspherical;

The image-side surface of the second lens is a convex surface, and at least one of the object-side surface and the image-side surface is an aspherical surface.

Preferably, the first two lenses of the first lens group arranged in sequence from the object side to the image side of the optical axis are arranged as follows:

The object side surface of the first lens is concave, the image side surface is convex, at least one of the object side surface and the image side surface is aspherical, and has a region with the largest thickness at the center and a decreasing thickness as the distance from the axis increases;

The object side surface of the second lens is convex, the image side surface is concave, and at least one of the object side surface and the image side surface is aspherical.

Preferably, the first two lenses of the first lens group arranged in sequence from the object side to the image side of the optical axis are arranged as follows:

The object side surface and the image side surface of the first lens are both concave surfaces, and at least one of the object side surface and the image side surface is aspherical;

The object-side surface of the second lens is a convex surface, and at least one of the object-side surface and the image-side surface is an aspherical surface.

Preferably, at least one of the object-side surface and the image-side surface of the first lens has an inflection point.

Preferably, the first lens group includes, in order from the object side to the image side along the optical axis:

The first lens has an object-side surface and an image-side surface both of which are concave surfaces, and at least one of the object-side surface and the image-side surface is an aspherical surface;

The second lens has a convex object surface and a concave image surface, and at least one of the object surface and the image surface is an aspherical surface and has a region with a maximum thickness at the center and a decreasing thickness as the thickness deviates from the axis.

The third lens has a concave object surface, but the concave degree is less than that of the object surface of the first lens, and the image surface is concave;

The fourth lens has convex object-side and image-side surfaces.

Preferably, the first lens group includes, in order from the object side to the image side along the optical axis:

The first lens has a concave object surface and a convex image surface, and at least one of the object surface and the image surface is an aspherical surface and has a region with a maximum thickness at the center and a decreasing thickness as the thickness increases away from the axis;

The second lens has a convex object surface and a concave image surface, and at least one of the object surface and the image surface is aspherical;

The third lens has convex object and image surfaces.

Preferably, the first lens group includes, in order from the object side to the image side along the optical axis:

The first lens has an object-side surface and an image-side surface both of which are concave surfaces, and at least one of the object-side surface and the image-side surface is an aspherical surface;

The second lens has a convex object surface and a concave image surface, and at least one of the object surface and the image surface is an aspherical surface and has a region with a maximum thickness at the center and a decreasing thickness as the thickness deviates from the axis.

The object side surface of the third lens is concave, but the concave degree is less than that of the object side surface of the first lens, and the image side surface is convex;

The fourth lens has concave object and image surfaces;

The fifth lens has convex object and image surfaces.

The above-mentioned preferred technical features can be combined with each other as long as they do not conflict with each other.

In general, the above technical solution conceived by the present invention has the following beneficial effects compared with the prior art:

1. In the prior art, the photosensitive surface of the photosensitive chip is located on the focal plane of the lens; when there is a focusing function, the photosensitive surface of the photosensitive chip is located between two planes determined by one focal length to two focal lengths of the lens within the focusing range. The present invention is different from the prior art, and the positional relationship between the lens and the photosensitive chip satisfies the relationship. This structure is conducive to reducing the distance from the image side end face of the lens to the photosensitive chip during close-range imaging, avoiding the use of a distance increase method to achieve close-range photography, and is conducive to the miniaturization of the structure.

2. As mentioned above, the structure of the present invention can avoid the need to increase the distance to achieve close-up photography, thereby making the module structure more compact, reducing the total thickness of the air medium on the image side, and thus avoiding wasting space. On this basis, the saved space can be used to increase the number of lenses in the lens, thereby enabling the lens to obtain more degrees of freedom for aberration correction, thereby achieving higher optical resolution and lower distortion.

3. In the camera module of the present invention, the lens includes a first lens group and a second lens group, which are constructed into a structure of a compound microscope. In this case, the first lens group is equivalent to an objective lens. This structure is conducive to obtaining excellent imaging quality under close-range imaging.

4. In the camera module of the present invention, the aperture in the lens is located in the middle position. The structure of the central aperture is beneficial to reducing lateral chromatic aberration during imaging and is also beneficial to achieving imaging with a large field of view angle.

5. In the camera module of the present invention, during the imaging process, the first lens group of the lens is in a state where the object distance is small and the image distance is large, and the second lens group is in a state where the object distance is large and the image distance is small. At this time, when there is an installation error between the first lens group and the second lens group, the installation error, especially the distance error, is much smaller than the image distance of the first lens group and the object distance of the second lens group, so that the installation error has less impact on the imaging quality, which is beneficial to reducing the sensitivity of the imaging quality to the installation error, thereby obtaining a higher yield rate.

6. Most traditional miniature lenses are photographic lenses, which are designed for situations where the object distance is much greater than the image distance and are not suitable for close-range macro and microscopic imaging. The camera module of the present invention proposes a lens configuration of a sandwich structure consisting of a first lens group, an aperture, and a second lens group, which can obtain a higher close-range imaging effect in a miniaturized state and can effectively reduce the aberrations during close-range imaging, especially distortion and chromatic aberration. The lens that meets the structural characteristics and parameter relationship of the present invention can effectively reduce the diameter of the lens, reduce the size of the lens, and reduce the difficulty and cost of processing, and can effectively reduce the total optical tube length of the structure consisting of the lens and the detector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a first type of camera module of the present invention;

FIG2 is a schematic diagram of a lens module of the first type of camera module of the present invention;

3 is a schematic structural diagram of a lens module of the first type of camera module of the present invention;

FIG4 is a schematic diagram of a second type of camera module of the present invention;

FIG5 is a schematic structural diagram of a camera module of the present invention;

FIG6 is a schematic diagram of the structure of Embodiment 1 of the present invention;

FIG7 is a schematic diagram of the structure of Embodiment 2 of the present invention;

FIG8 is a schematic diagram of the structure of Embodiment 3 of the present invention;

FIG9 is a schematic diagram of the structure of Embodiment 4 of the present invention;

FIG10 is a schematic diagram of distortion within the viewing angle of Embodiment 4 of the present invention;

FIG11 is a schematic diagram of the structure of Embodiment 5 of the present invention;

FIG12 is a diagram of a parameter table of Embodiment 1 of the present invention;

FIG13 is a second parameter table diagram of the first embodiment of the present invention;

FIG14 is a diagram of a parameter table of Embodiment 2 of the present invention;

FIG15 is a second parameter table diagram of the second embodiment of the present invention;

FIG16 is a diagram of a parameter table of Embodiment 3 of the present invention;

FIG17 is a second parameter table diagram of the third embodiment of the present invention;

FIG18 is a diagram showing a parameter table of the fourth embodiment of the present invention;

FIG19 is a second parameter table diagram of the fourth embodiment of the present invention;

FIG20 is a diagram of a parameter table of Embodiment 5 of the present invention;

FIG. 21 is a second parameter table diagram of the fifth embodiment of the present invention.

Detailed ways

In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention is further described in detail below in conjunction with specific embodiments.

As shown in FIGS. 1-4 , the present invention provides a camera module, which includes a lens module 10 , a housing 20 , a base plate 30 and a photosensitive chip 600 .

The lens module 10 includes a lens group and a required supporting mechanical structure.

The housing 20 is used to fix the lens module 10 and the base plate 30 ; preferably, the housing 20 is made of metal or plastic.

The bottom plate 30 is fixed to the housing 20, and a photosensitive chip 600 is mounted on the bottom plate 30. The bottom plate 30 is used to provide mechanical support and circuit connection. A circuit is printed on the bottom plate 30, and if necessary, includes electronic components that cooperate with the photosensitive chip 600.

The photosensitive chip 600 is a planar array photoelectric detector. Preferably, the photosensitive chip 600 is a CMOS image sensor or a CCD image sensor.

The lens group of the lens module 10 is a lens suitable for close-range imaging (including but not limited to macro imaging and microscopic imaging). Specifically, when the lens module 10 is imaging, the mean square error radius of the focused image point when the distance from the object point on the optical axis to the object side principal surface of the lens module 10 is less than 40 mm is smaller than the mean square error radius of the focused image point when the object point on the optical axis is at infinity.

The lens module 10 includes, in order from the object side to the image side along the optical axis: a first lens group 100 , an aperture 300 , and a second lens group 200 .

The first lens group 100 and the second lens group 200 are both positive optical power; the object side aperture of the first lens group 100 is larger than the image side aperture, and the object side aperture of the second lens group 200 is smaller than the image side aperture; the first lens group 100 and the second lens group 200 are both lens groups consisting of two or more lenses, and both include aspherical lenses. The materials of the lenses in the first lens group 100 and the second lens group 200 are transparent plastic or glass.

The positional relationship between the lens module 10 and the photosensitive surface of the photosensitive chip 600 satisfies the following conditions:

0.5f ₂₀₀ <S _ima <1.5f ₂₀₀ (Formula 1);

Wherein _f200 is the focal length of the second lens group 200, that is, the distance from the image-side principal surface 2001 of the second lens group to the image-side focal plane 2002 of the second lens group, and _Sima is the distance from the photosensitive surface of the photosensitive chip 600 to the image-side principal surface 2001 of the second lens group, as shown in FIG2 .

The image-side medium of the first lens group 100 and the object-side medium of the second lens group 200 can be air, plastic, glass or other transparent materials.

When the image-side medium of the first lens group 100 and the object-side medium of the second lens group 200 are air, the aperture 300 is located on the surface of the first lens group 100 or the second lens group 200 , or in the air medium on the object side or the image side thereof.

When the image-side medium of the first lens group 100 and the object-side medium of the second lens group 200 are transparent materials including plastic or glass; in this case, the first lens group 100 and the second lens group 200 have a common lens, all the lenses on the object side of the lens and the object-side surface of the lens constitute the first lens group 100, and the image-side surface of the lens and all the lenses on its image side constitute the second lens group 200; the aperture 300 is located on the surface of the lens or in the transparent medium of the lens. In this case where the first lens group 100 and the second lens group 200 share a lens, the number of lenses can be reduced, making the structure of the lens module 10 more compact, thereby facilitating miniaturization.

As the first type of structure, as shown in FIG1 , if necessary, there is a filter 400 in front of the photosensitive chip. Preferably, the filter 400 is an infrared filter. Specifically, the camera module further includes a filter 400; the filter 400 is installed on the object side of the photosensitive chip 600 and fixed on the housing 20.

When a filter 400 is further included between the lens module 10 and the photosensitive chip 600, the filter 400, as a flat optical element, will affect the image-side optical parameters of the lens module 10, and the position from the image-side principal surface 2001 of the second lens group to the image-side focal plane 2002 of the second lens group is the position after considering the refraction effect of the filter 400.

For situations where focusing is required, the camera module further includes a focusing motor, which is a voice coil motor or an ultrasonic motor. The focusing motor is used to move the lens module 10 relative to the housing 20 .

As shown in FIG3 , the camera module further includes a magnet 1001, a front spring pad 1002, a rear spring pad 1003, and a coil 1004; the magnet 1001 and the coil 1004 constitute the focus motor; the magnet 1001 is fixed to the inner wall of the housing 20, the front spring pad 1002 and the rear spring pad 1003 are used to limit the moving position of the lens module 10, and the coil 1004 is fixed to the outer wall of the lens module 10. At this time, the lens module 10 has a focus function.

When the lens module 10 has a focusing function, after focusing by a focusing motor, the positional relationship between the lens module 10 and the photosensitive chip 600 also satisfies Formula 1.

As the second type of structure, as shown in FIG. 4 , the camera module does not have a focusing function, and the distance between the lens module 10 and the photosensitive chip 600 is a fixed value; camera modules of different specifications produce a series of different fixed values, but all satisfy Formula 1.

Preferably, when the camera module does not have a focusing function, the positional relationship between the lens module 10 and the photosensitive surface of the photosensitive chip 600 satisfies the following conditions:

_{Sima＝ f200} (Formula 2).

The camera module of the present invention is described in further detail below.

As shown in FIG. 5 , the present invention provides a miniature imaging lens for close-range imaging, wherein: along an optical axis from the object side to the image side, the lens comprises: a first lens group 100 , an aperture 300 , and a second lens group 200 .

The first lens group 100 and the second lens group 200 both have positive optical power; the object-side clear aperture of the first lens group 100 is larger than the image-side clear aperture, and the object-side clear aperture of the second lens group 200 is smaller than the image-side clear aperture; the focal length f 100 of the first lens group 100 is ≤40 _mm , and the focal length f ₂₀₀ of the second lens group 200 is ≤20 mm;

When in use, the distance _od100 between the object 500 to be photographed and the object-side principal surface of the first lens group 100 is less than twice the focal length of the first lens group 100, that is,

od ₁₀₀ <2f ₁₀₀ (Equation 1);

And the distance id ₂₀₀ from the image side principal surface of the second lens group (200) to the image plane is less than twice the focal length of the second lens group 200, that is,

id ₂₀₀ <2f ₂₀₀ (relation 2);

Under the conditions determined by the above two equations, for close-range imaging, especially ultra-close-range imaging, the distance from the image surface of the second lens group 200 to the detector 600 can be significantly reduced, which is beneficial to reducing the total optical tube length and facilitating miniaturization of the equipment.

The image-side numerical aperture NA _img100 of the first lens group 100 and the object-side numerical aperture NA _obj200 of the second lens group 200 satisfy the following conditions:

0<NA _img100 , NA _obj200 <0.05 (Equation 3).

After the object 500 to be photographed is imaged by the first lens group 100 and the second lens group 200, it is finally imaged on the photosensitive surface of the detector 600. Further, when there is a requirement for wavelength selection, a filter 400 is also included between the second lens group 200 and the photosensitive surface of the detector 600. Since the numerical aperture of the light beam in the space between the first lens group 100 and the second lens group 200 is small, it is convenient to reduce the influence of manufacturing and assembly errors on the quality of the light beam, so this design is conducive to improving the yield rate during production. The second lens group 200 has at least one lens, whose image side surface is aspherical, the curved surface is concave near the optical axis, and the slope of the curved surface (referring to the absolute value of the arc tangent of the angle between the tangent of the curve formed by the intersection of the curved surface and the meridian plane and the optical axis) decreases after a distance away from the optical axis. This design is conducive to suppressing the aberration of the off-axis field of view under the condition of large field of view, especially suppressing astigmatism and field curvature, so as to improve the imaging quality of the present invention under the condition of large object side field of view.

The aperture 300 is a physical entity that can define the aperture. The outer side of the first lens group 100 is defined as the object side of the entire lens, and the outer side of the second lens group is defined as the image side of the entire lens. The aperture 300 is located between the first lens group 100 and the second lens group 200, which is conducive to correcting distortion and chromatic aberration in imaging.

The distance _sd100 from the aperture 300 to the edge of the first lens group 100 along the optical axis direction satisfies the relationship:

sd ₁₀₀ <f ₁₀₀ (Equation 4);

The distance _sd200 from the aperture 300 to the edge of the second lens group 200 along the optical axis direction satisfies the relationship:

sd ₂₀₀ <f ₂₀₀ (Equation 5).

When the distance between the aperture 300 and the first lens group 100 and the second lens group 200 satisfies the relationship expressed by equations 4 and 5, it is beneficial to reduce the light height on the image surface of the first lens group 100 and the object surface of the second lens group 200 (i.e., the distance from the intersection of the light and the surface to the optical axis) in the case of large field of view imaging, thereby facilitating the reduction of the diameter of the first lens group 100 and the second lens group 200, facilitating miniaturization and reducing processing costs (large diameter lenses have high processing costs); further, it is also convenient for the first lens on the image side of the first lens group 100 and the first lens on the object side of the second lens group 200 to correct low-order spherical aberrations, thereby improving imaging quality. In summary, the beneficial effects of the present invention are: a sandwich-structured lens consisting of a first lens group 100, an aperture 300 and a second lens group 200 is proposed, which can effectively reduce aberrations, especially distortion and chromatic aberrations, during close-range imaging. A lens that satisfies the structural characteristics and parameter relationships described above can effectively reduce the diameter of the lens, reduce the size of the lens, reduce the difficulty and cost of processing, and can effectively reduce the total optical tube length of the structure consisting of the lens and the detector.

In the present invention, the second lens group 200 includes at least three lenses in sequence from the object side to the image side of the optical axis; the first lens group 100 includes at least three lenses in sequence from the object side to the image side of the optical axis. The number of the first lens group 100 and the second lens group 200 can be freely combined, and different structural settings can also be freely combined; the first lens group 100 and/or the second lens group 200 have an integral axial adjustment device; further, at least one lens in the first lens group 100 and/or the second lens group 200 has its own separate axial adjustment device.

The last two lenses of the second lens group 200 are arranged in sequence from the object side to the image side of the optical axis in the following four ways:

The first type of second lens group: the image surface of the penultimate lens is convex, and at least one of its object surface and image surface is aspherical; the object surface and image surface of the last lens are both concave, and at least one of its object surface and image surface is aspherical.

The second lens group of the second type: the image surface of the penultimate lens is convex, and at least one of its object surface and image surface is aspherical; the object surface of the last lens is convex, the image surface is concave, and at least one of its object surface and image surface is aspherical, and has a region with the smallest central thickness and increasing thickness as it moves away from the axis.

The third type of the second lens group: the object surface of the penultimate lens is concave, the image surface is convex, and at least one of the object surface and the image surface is aspherical; the object surface of the last lens is concave, the image surface is convex, and at least one of the object surface and the image surface is aspherical.

The fourth type of the second lens group: the image surface of the penultimate lens is convex, and at least one of its object surface and image surface is aspherical; the object surface of the last lens is convex, the image surface is concave, and at least one of its object surface and image surface is aspherical, and has a region with the largest central thickness and a region with decreasing thickness as it moves away from the axis.

In various second lens groups: at least one of the object-side surface and the image-side surface of the last lens has an inflection point.

The first two lenses of the first lens group 100 are arranged in sequence from the object side to the image side of the optical axis in the following three ways:

The first lens group of the first type: the object side surface and the image side surface of the first lens are both concave, and at least one of the object side surface and the image side surface is aspherical; the image side surface of the second lens is convex, and at least one of the object side surface and the image side surface is aspherical.

The second type of first lens group: the object surface of the first lens is concave, the image surface is convex, at least one of the object surface and the image surface is aspherical, and has a region with the largest central thickness and decreasing thickness as it moves away from the axis; the object surface of the second lens is convex, the image surface is concave, and at least one of the object surface and the image surface is aspherical.

The third first lens group: the object side surface and the image side surface of the first lens are both concave, and at least one of the object side surface and the image side surface is aspherical; the object side surface of the second lens is convex, and at least one of the object side surface and the image side surface is aspherical.

At least one of the object-side surface and the image-side surface of the first lens in each first lens group has an inflection point.

All lenses have their applicable object distance range. A situation in which the present invention works well is that the object plane 500 is located at the object-side focal plane of the first lens group 100, and the photosensitive surface of the detector 600 is located at the image-side focal plane of the second lens group 200. When the second lens group 200 further includes a filter 400, the image-side focal plane of the second lens group 200 is the actual focal plane after considering the refraction effect of the filter 400. In this case, the light emitted by an object point on the object plane 500 after passing through the first lens group 100 is approximately collimated light, and the collimated light forms an object point on the photosensitive surface of the detector 600 after being focused by the second lens group 200. When the object plane 500 is not in the above-mentioned ideal position, further focusing is required, which can be achieved by adjusting the distance of the first lens group 100 and the second lens group 200 of the present invention relative to the detector 600, or by adjusting one of the first lens group 100 or the second lens group 200 of the present invention.

The lens in the lens of the present invention can be glass, plastic or other light-transmitting materials. When plastic materials are used, the weight and cost can be effectively reduced. The light-transmitting surface of the lens can be aspherical, so as to obtain more degrees of freedom for aberration correction, thereby better correcting aberrations. And the second lens group 200 of the present invention has at least one lens whose image-side surface is aspherical, and the curve formed by the cross-section through the optical axis of the lens contains an inflection point, that is, the concave-convexity of the surface is changed. This design is conducive to suppressing the aberration of the off-axis field of view in the case of a large field of view, so as to improve the imaging quality of the present invention when the object-side field of view is large.

The aperture 300 of the present invention is placed in the middle of the lens, and the so-called middle of the lens means that both the object side and the image side of the aperture contain lenses. This aperture setting method is called a center aperture. Centering the aperture helps to improve the field of view and has a good inhibitory effect on distortion and chromatic aberration. Preferably, the micro imaging lens for close-range imaging is a micro imaging lens for portable electronic products.

Furthermore, the lens described in the present invention includes a mechanical housing as a package, and forms an imaging module with a motor, an array photodetector (such as a CMOS image sensor, etc.), etc., which can be used in electronic products such as mobile phones, tablet computers, wearable devices (such as smart bracelets, smart watches, etc.), small cameras (such as sports cameras, etc.), etc., to achieve close-range imaging functions and even microscopic imaging functions.

Specific embodiments of the present invention are presented below.

<First Embodiment>

The first embodiment of the present invention is shown in FIG6 . The first lens group 100 includes 4 lenses, and the second lens group 200 includes 5 lenses. The above 9 lenses are all aspherical lenses. The surface shape of the aspherical lens is expressed by the curve equation as follows (the aspherical surface is formed by rotating the curve around the optical axis):

in:

X: The relative distance between the point on the aspheric surface that is Y away from the optical axis and the tangent plane that is tangent to the focus on the optical axis of the aspheric surface;

Y: the vertical distance between the point on the aspheric curve and the optical axis;

r: radius of curvature;

k: cone coefficient;

A _i : i-th order aspheric coefficient.

The parameters of each surface of the lens in this embodiment are shown in FIG. 12 and FIG. 13 .

In Figure 12, the units of length-type physical quantities such as the radius of curvature r and thickness t are all millimeters; surfaces 1 to 18 are the surfaces from the object side to the image side of the present invention, and surfaces 19 to 20 are filters. In Figure 13, A2 to A14 are the aforementioned 2nd to 14th order aspheric coefficients.

The object side surface of the first lens of the first lens group 100 of this embodiment is an aspherical surface, and the curved surface is concave near the optical axis, and there is an inflection point when the curved surface is away from the optical axis for a certain distance, and the image side surface is an aspherical surface, which is a concave surface; the object side surface of the second lens is an aspherical surface, and it is convex near the optical axis, and the image side surface is a concave surface. The second lens as a whole is thicker in the center than around; the object side surface of the third lens is also a concave surface, but the degree of concavity is weaker than that of the object side surface of the first lens, and the image side surface is a concave surface, and both the object side surface and the image side surface are aspherical surfaces; the object side surface and the image side surface of the fourth lens are both convex surfaces of aspherical surfaces.

The object side surface and the image side surface of the first lens of the second lens group 200 of this embodiment are both convex aspherical surfaces; the object side surface and the image side surface of the second lens are both concave aspherical surfaces; the object side surface of the third lens is convex at the center, and then a concave surface appears at an off-axis position, and the image side surface is concave at the center, and then a convex surface appears at an off-axis position; the object side surface of the fourth lens is a relatively flat aspherical surface, and the image side surface is a convex aspherical surface; the object side surface of the last lens is a concave aspherical surface, and its image side surface is an aspherical surface, the curved surface is concave near the optical axis, and there is an inflection point when the curved surface is away from the optical axis for a certain distance.

The lens shown in this embodiment can obtain an object-side numerical aperture of more than 0.15 under a field of view angle of ±30°, and the Strehl ratio in most areas within the entire field of view can be higher than 0.9, thereby achieving good imaging quality.

<Second Embodiment>

The second embodiment of the present invention is shown in FIG7 . The first lens group 100 includes 4 lenses, and the second lens group 200 includes 4 lenses. The parameters of each surface of the lens in this embodiment are shown in FIG14 and FIG15 , and the definition of variables is similar to the above, and will not be repeated.

The object side surface of the first lens of the first lens group 100 of this embodiment is an aspherical surface, and the curved surface is concave near the optical axis, and there is an inflection point when the curved surface is away from the optical axis for a certain distance, and the image side surface is an aspherical surface, which is a concave surface; the object side surface of the second lens is an aspherical surface, and it is convex near the optical axis, and the image side surface is a concave surface. The second lens as a whole is thicker in the center than around; the object side surface of the third lens is also a concave surface, but the degree of concavity is weaker than that of the object side surface of the first lens, and the image side surface is a concave surface, and both the object side surface and the image side surface are aspherical surfaces; the object side surface and the image side surface of the fourth lens are both convex surfaces of aspherical surfaces.

In the second lens group 200 of this embodiment, the object side surface and the image side surface of the first lens are both convex aspheric surfaces; the object side surface and the image side surface of the second lens are both concave aspheric surfaces, wherein the object side surface is more concave than the image side surface, and the image side surface has an inflection point at an off-axis position; the object side surface of the third lens is concave at the center, and the image side surface is a convex aspheric surface; the object side surface of the last lens is a convex aspheric surface, and the image side surface is a concave aspheric surface, and the center thickness is less than the thickness at the off-axis position.

Compared with the first embodiment, this embodiment has a smaller magnification ratio and is suitable for occasions requiring a smaller magnification ratio.

<Third Embodiment>

The third embodiment of the present invention is shown in Fig. 8, the first lens group 100 includes 3 lenses, and the second lens group 200 includes 4 lenses. The parameters of the lens surfaces in this embodiment are shown in Fig. 16 and Fig. 17, and the variable definitions are similar to the above, and will not be repeated.

The object-side surface of the first lens of the first lens group 100 of this embodiment is an aspherical surface, the curved surface is concave near the optical axis, and there is an inflection point when the curved surface is a certain distance away from the optical axis, and the image-side surface is a convex surface of the aspherical surface; the object-side surface of the second lens is a convex surface of the aspherical surface, and the image-side surface is a concave surface of the aspherical surface; the object-side surface and the image-side surface of the third lens are both convex surfaces of the aspherical surface.

The object side surface and the image side surface of the first lens of the second lens group 200 of this embodiment are both convex aspherical surfaces; the object side surface and the image side surface of the second lens are both concave aspherical surfaces; the object side surface of the third lens is convex at the center, and then a concave surface appears at an off-axis position, and the image side surface is concave at the center, and then a convex surface appears at an off-axis position; the object side surface of the fourth lens is a relatively flat aspherical surface, and the image side surface is a convex aspherical surface; the object side surface of the last lens is a concave aspherical surface, and its image side surface is an aspherical surface, the curved surface is concave near the optical axis, and there is an inflection point when the curved surface is away from the optical axis for a certain distance.

This embodiment has fewer lenses, which can reduce costs, but the wide-angle performance is weaker than the previous embodiment.

<Fourth Embodiment>

The fourth embodiment of the present invention is shown in Figure 9, the first lens group 100 includes 5 lenses, and the second lens group 200 includes 6 lenses. The parameters of the lens surfaces in this embodiment are shown in Figures 18 and 19, and the variable definitions are similar to the above, and will not be repeated.

The object side surface of the first lens of the first lens group 100 of this embodiment is an aspheric surface, the curved surface is concave near the optical axis, and there is an inflection point when the curved surface is away from the optical axis for a certain distance, and the image side surface is a concave surface of the aspheric surface; the object side surface of the second lens is an aspheric surface, and is convex near the optical axis, and the image side surface is a relatively flat aspheric concave surface, and the second lens as a whole is thicker in the center than around; the object side surface of the third lens is also a concave surface of the aspheric surface, but the degree of concavity is weaker than that of the object side surface of the first lens, and the image side surface is a convex surface of the aspheric surface; the object side surface and the image side surface of the fourth lens are both concave surfaces of the aspheric surface; the object side surface and the image side surface of the last lens are both convex surfaces of the aspheric surface.

The object side surface and the image side surface of the first lens of the second lens group 200 of this embodiment are both convex aspherical surfaces; the object side surface of the second lens is a convex aspherical surface, and the image side surface is a concave aspherical surface; the object side surface of the third lens is convex at the center, and then a concave surface appears at an off-axis position, and the image side surface is concave at the center, and then a convex surface appears at an off-axis position; the object side surface of the fourth lens is a relatively flat aspherical surface, and the image side surface is a convex aspherical surface; the object side surface of the fifth lens is a concave aspherical surface, and its image side surface is a convex aspherical surface; for the last lens, the object side surface is concave near the optical axis, and the image side surface is a relatively flat aspherical surface, with a slight convex surface at the center.

This embodiment uses more lenses to correct aberrations, and can obtain good wide-angle performance, especially the distortion within the ±30° field angle is less than 0.7% (as shown in FIG. 10 ), which is very excellent for wide-angle imaging.

<Fifth Embodiment>

The fifth embodiment of the present invention is shown in Figure 11, the first lens group 100 includes 3 lenses, and the second lens group 200 includes 3 lenses. The parameters of the lens surfaces in this embodiment are shown in Figures 20 and 21, and the variable definitions are similar to the above, which will not be repeated.

The object-side surface of the first lens of the first lens group 100 of this embodiment is an aspherical surface, the curved surface is concave near the optical axis, and there is an inflection point when the curved surface is a certain distance away from the optical axis, and the image-side surface is a convex surface of the aspherical surface; the object-side surface of the second lens is a convex surface of the aspherical surface, and the image-side surface is a concave surface of the aspherical surface; the object-side surface and the image-side surface of the third lens are both convex surfaces of the aspherical surface.

In the second lens group 200 of this embodiment, the object-side surface and the image-side surface of the first lens are both aspherical convex surfaces, the object-side surface of the second lens is a concave aspherical surface, and the image-side surface is a convex aspherical surface; the object-side surface center of the third lens is a convex aspherical surface, and the image-side surface center is a concave aspherical surface, and there is an inflection point when the curved surface is away from the optical axis for a certain distance.

This embodiment has a small number of lenses, which is convenient for reducing costs, but the flat field performance is reduced.

It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (30)

1. A camera module, characterized in that it comprises a lens module (10), a housing (20), a base plate (30) and a photosensitive chip (600); The housing (20) is used to fix the lens module (10) and the base plate (30); The photosensitive chip (600) is mounted on the bottom plate (30); The mean square error radius of the focused image point when the distance from the object point on the optical axis to the object side principal surface of the lens module (10) is less than 40 mm is smaller than the mean square error radius of the focused image point when the object point on the optical axis is located at infinity; The lens module (10) comprises, in order from the object side to the image side of the optical axis: a first lens group (100), an aperture (300), and a second lens group (200); The first lens group (100) and the second lens group (200) both have positive optical power; the object-side clear aperture of the first lens group (100) is larger than the image-side clear aperture, and the object-side clear aperture of the second lens group (200) is smaller than the image-side clear aperture; The positional relationship between the lens module (10) and the photosensitive surface of the photosensitive chip (600) satisfies the following conditions: 0.5f ₂₀₀ <S _ima <1.5f ₂₀₀ (Formula 1) Wherein _f200 is the focal length of the second lens group (200), that is, the distance from the image-side principal surface (2001) of the second lens group to the image-side focal surface (2002) of the second lens group, and _Sima is the distance from the photosensitive surface of the photosensitive chip (600) to the image-side principal surface (2001) of the second lens group. 2. The camera module according to claim 1, wherein: The camera module also includes a filter (400); The optical filter (400) is mounted on the object side of the photosensitive chip (600) and fixed on the housing (20); The position from the image-side principal surface (2001) of the second lens group to the image-side focal surface (2002) of the second lens group is the position after the refraction effect of the filter (400) is taken into account. 3. The camera module according to claim 1, wherein: The camera module also includes a focus motor; The focus motor is used to move the lens module (10) relative to the housing (20), and within the focus range of the lens module (10), Formula 1 is established. 4. The camera module according to claim 3, wherein: The focusing motor is a voice coil motor or an ultrasonic motor. 5. The camera module according to claim 3, wherein: The camera module also includes a magnet (1001), a front spring pad (1002), a rear spring pad (1003), and a coil (1004); The magnet (1001) and the coil (1004) constitute the focus motor; The magnet (1001) is fixed to the inner wall of the housing (20), the front spring pad (1002) and the rear spring pad (1003) are used to limit the moving position of the lens module (10), and the coil (1004) is fixed to the outer wall of the lens module (10). 6. The camera module according to claim 1, wherein: The camera module does not have a focusing function, and the distance between the lens module (10) and the photosensitive chip (600) is a fixed value; The camera modules of different specifications produce a series of different constants, but all satisfy Formula 1. 7. The camera module according to claim 6, wherein: When the camera module does not have a focusing function, the positional relationship between the lens module (10) and the photosensitive surface of the photosensitive chip (600) satisfies the following conditions: _{Sima＝ f200} (Formula 2). 8. The camera module according to claim 1, wherein: The image-side medium of the first lens group (100) and the object-side medium of the second lens group (200) are air; The aperture (300) is located on the surface of the first lens group (100) or the second lens group (200), or in the air medium on the object side or the image side thereof. 9. The camera module according to claim 1, wherein: The image-side medium of the first lens group (100) and the object-side medium of the second lens group (200) are made of transparent materials including plastic or glass; In this case, the first lens group (100) and the second lens group (200) have a common lens, all lenses on the object side of the lens and the object side surface of the lens constitute the first lens group (100), and the image side surface of the lens and all lenses on the image side constitute the second lens group (200); The aperture (300) is located on the surface of the lens or in the transparent medium of the lens. 10. The camera module according to claim 1, wherein: The camera module is a camera module used for portable electronic products. 11. The camera module according to any one of claims 1 to 10, characterized in that: The focal length _f100 of the first lens group (100) is ≤40 mm, and the focal length _f200 of the second lens group (200) is ≤20 mm; When in use, the distance _od100 between the object to be photographed (500) and the object-side principal surface of the first lens group (100) is less than twice the focal length of the first lens group 100, that is, od ₁₀₀ <2f ₁₀₀ ; And the distance id ₂₀₀ from the image side principal surface of the second lens group (200) to the image plane is less than twice the focal length of the second lens group (200), that is, id ₂₀₀ <2f ₂₀₀ ; Furthermore, the image-side numerical aperture NA _img100 of the first lens group (100) and the object-side numerical aperture NA _obj200 of the second lens group (200) satisfy the following conditions: 0<NA _img100 , NA _obj200 <0.05. 12. The camera module according to claim 11, wherein: The distance _sd100 from the aperture (300) to the edge of the first lens group (100) along the optical axis direction satisfies the relationship: sd ₁₀₀ < f ₁₀₀ ; The distance _sd200 from the aperture (300) to the edge of the second lens group (200) along the optical axis direction satisfies the relationship: sd ₂₀₀ <f ₂₀₀ . 13. The camera module according to claim 11, wherein: The second lens group (200) includes at least three lenses in sequence from the object side to the image side of the optical axis. 14. The camera module according to claim 13, wherein: The last two lenses of the second lens group (200) arranged in sequence from the object side to the image side of the optical axis are arranged as follows: The image-side surface of the penultimate lens is convex, and at least one of the object-side surface and the image-side surface is aspherical; The object side surface and the image side surface of the last lens are both concave surfaces, and at least one of the object side surface and the image side surface is aspherical. 15. The camera module according to claim 13, wherein: The last two lenses of the second lens group (200) arranged in sequence from the object side to the image side of the optical axis are arranged as follows: The image-side surface of the penultimate lens is convex, and at least one of the object-side surface and the image-side surface is aspherical; The object side surface of the last lens is convex, the image side surface is concave, at least one of the object side surface and the image side surface is aspherical, and has a region with the smallest central thickness and a greater thickness as it moves away from the axis. 16. The camera module according to claim 13, wherein: The last two lenses of the second lens group (200) arranged in sequence from the object side to the image side of the optical axis are arranged as follows: The object side surface of the penultimate lens is concave, the image side surface is convex, and at least one of the object side surface and the image side surface is aspherical; The object side surface of the last lens is concave, the image side surface is convex, and at least one of the object side surface and the image side surface is aspherical. 17. The camera module according to claim 13, wherein: The last two lenses of the second lens group (200) arranged in sequence from the object side to the image side of the optical axis are arranged as follows: The image-side surface of the penultimate lens is convex, and at least one of the object-side surface and the image-side surface is aspherical; The object side surface of the last lens is convex, the image side surface is concave, at least one of the object side surface and the image side surface is aspherical, and has a region with the largest central thickness and a decreasing thickness as it moves away from the axis. 18. The camera module according to any one of claims 14 to 17, characterized in that: At least one of the object-side surface and the image-side surface of the last lens has an inflection point. 19. The camera module according to claim 13, wherein: The second lens group (200) comprises, in order from the object side to the image side along the optical axis: The first lens has a convex object-side surface and an image-side surface; The second lens has a concave object-side surface and an image-side surface; The third lens has a convex surface at the center of the object side and then becomes concave at the off-axis periphery, and a concave surface at the center of the image side and then becomes convex at the off-axis periphery; The image-side surface of the fourth lens is convex, and at least one of the object-side surface and the image-side surface is aspherical; The object-side surface and the image-side surface of the fifth lens are both concave surfaces, and at least one of the object-side surface and the image-side surface is aspherical. 20. The camera module according to claim 13, wherein: The second lens group (200) comprises, in order from the object side to the image side along the optical axis: The first lens has a convex object-side surface and an image-side surface; The second lens has an object-side surface and an image-side surface both of which are concave surfaces, wherein the object-side surface is more concave than the image-side surface, and the image-side surface has an inflection point; The third lens has an image-side surface that is convex, and at least one of its object-side surface and image-side surface that is aspherical; The fourth lens has a convex object surface and a concave image surface. At least one of the object surface and the image surface is aspherical and has a region with the smallest central thickness and a greater thickness as it moves away from the axis. 21. The camera module according to claim 13, wherein: The second lens group (200) comprises, in order from the object side to the image side along the optical axis: The first lens has a convex object-side surface and an image-side surface; The second lens has a convex object surface and a concave image surface; The third lens has a convex surface at the center of the object side and then becomes concave at the off-axis periphery, and a concave surface at the center of the image side and then becomes convex at the off-axis periphery; The fourth lens has a concave object surface and a convex image surface; a fifth lens having a concave object-side surface and a convex image-side surface, and at least one of the object-side surface and the image-side surface is aspherical; The sixth lens has a concave object-side surface and a convex image-side surface, and at least one of the object-side surface and the image-side surface is an aspherical surface. 22. The camera module according to claim 13, wherein: The second lens group (200) comprises, in order from the object side to the image side along the optical axis: The first lens has a convex object-side surface and an image-side surface; The second lens has an image-side surface that is convex, and at least one of an object-side surface and an image-side surface that is aspherical; The third lens has a convex object surface and a concave image surface. At least one of the object surface and the image surface is aspherical and has a region with the largest central thickness and a decreasing thickness as the thickness deviates from the axis. 23. The camera module according to claim 11, wherein: The first lens group (100) includes at least three lenses in sequence from the object side to the image side of the optical axis. 24. The camera module according to claim 23, wherein: The first two lenses of the first lens group (100) arranged in sequence from the object side to the image side of the optical axis are arranged as follows: The object side surface and the image side surface of the first lens are both concave surfaces, and at least one of the object side surface and the image side surface is aspherical; The image-side surface of the second lens is a convex surface, and at least one of the object-side surface and the image-side surface is an aspherical surface. 25. The camera module according to claim 23, wherein: The first two lenses of the first lens group (100) arranged in sequence from the object side to the image side of the optical axis are arranged as follows: The object side surface of the first lens is concave, the image side surface is convex, at least one of the object side surface and the image side surface is aspherical, and has a region with the largest thickness at the center and a decreasing thickness as the distance from the axis increases; The object side surface of the second lens is convex, the image side surface is concave, and at least one of the object side surface and the image side surface is aspherical. 26. The camera module according to claim 23, wherein: The first two lenses of the first lens group (100) arranged in sequence from the object side to the image side of the optical axis are arranged as follows: The object side surface and the image side surface of the first lens are both concave surfaces, and at least one of the object side surface and the image side surface is aspherical; The object-side surface of the second lens is a convex surface, and at least one of the object-side surface and the image-side surface is an aspherical surface. 27. The camera module according to any one of claims 24 to 26, characterized in that: At least one of the object-side surface and the image-side surface of the first lens has an inflection point. 28. The camera module according to claim 23, wherein: The first lens group (100) comprises, in order from the object side to the image side along the optical axis: The first lens has an object-side surface and an image-side surface both of which are concave surfaces, and at least one of the object-side surface and the image-side surface is an aspherical surface; The second lens has a convex object surface and a concave image surface, and at least one of the object surface and the image surface is an aspherical surface and has a region with a maximum thickness at the center and a decreasing thickness as the thickness deviates from the axis. The third lens has a concave object surface, but the concave degree is less than that of the object surface of the first lens, and the image surface is concave; The fourth lens has convex object-side and image-side surfaces. 29. The camera module according to claim 23, wherein: The first lens group (100) comprises, in order from the object side to the image side along the optical axis: The first lens has a concave object surface and a convex image surface, and at least one of the object surface and the image surface is an aspherical surface and has a region with a maximum thickness at the center and a decreasing thickness as the thickness increases away from the axis; The second lens has a convex object surface and a concave image surface, and at least one of the object surface and the image surface is aspherical; The third lens has convex object and image surfaces. 30. The camera module according to claim 23, wherein: The first lens group (100) comprises, in order from the object side to the image side along the optical axis: The first lens has an object-side surface and an image-side surface both of which are concave surfaces, and at least one of the object-side surface and the image-side surface is an aspherical surface; The second lens has a convex object surface and a concave image surface, and at least one of the object surface and the image surface is an aspherical surface and has a region with a maximum thickness at the center and a decreasing thickness as the thickness deviates from the axis. The object side surface of the third lens is concave, but the concave degree is less than that of the object side surface of the first lens, and the image side surface is convex; The fourth lens has concave object and image surfaces; The fifth lens has convex object and image surfaces.