CN112505884A

CN112505884A - Optical system, image capturing module and electronic device

Info

Publication number: CN112505884A
Application number: CN202011422653.0A
Authority: CN
Inventors: 邹金华; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2020-12-08
Filing date: 2020-12-08
Publication date: 2021-03-16

Abstract

The application relates to an optical system, an image capturing module and an electronic device. The optical system comprises, in order from an object side to an image side along an optical axis: a first lens having a positive optical power; a second lens element having a negative power, the object-side surface of the second lens element being convex at a paraxial region and convex at a peripheral region; a third lens having optical power; a fourth lens having a positive optical power; the optical lens comprises a fifth lens with negative focal power, wherein the object-side surface of the fifth lens is a concave surface at a paraxial region and a concave surface at a peripheral region, both the object-side surface and the image-side surface of the fifth lens are aspheric, and at least one surface of the object-side surface and the image-side surface of the fifth lens comprises at least one inflection point; and a sixth lens element having negative optical power, the sixth lens element having a convex object-side surface at a paraxial region and a convex object-side surface at a peripheral region. The above optical system can balance the realization of a small head, the expansion of the field angle range, and the guarantee of high-quality imaging while satisfying a specific relationship.

Description

Optical system, image capturing module and electronic device

Technical Field

The present invention relates to the field of optical imaging technologies, and in particular, to an optical system, an image capturing module and an electronic device.

Background

With the continuous development of the related camera shooting technology, the camera shooting function becomes a standard matching function of the intelligent electronic product, the demand of consumers on the electronic product with ideal camera shooting effect is higher and higher, and the camera shooting effect is excellent under the application of some high-pixel optical lenses matched with an optimization software algorithm, so that excellent experience is brought to the consumers. However, as the performance and size of the conventional photosensitive elements such as Charge Coupled Devices (CCD) and Complementary Metal Oxide Semiconductor (CMOS) devices increase, the number of pixels on the photosensitive elements also increases and the size of the pixels becomes smaller, so as to provide higher requirements for the imaging resolution and miniaturization of the imaging lens.

On the other hand, the appearance of the mobile phone hole digging screen attracts the attention of consumers, and the camera module is packaged in a small area of the screen, which is closely related to the design of the appearance of the lens, and the requirement on the specification of the lens is higher and higher. Therefore, how to design a mobile phone lens with a small head caliber and a long depth, which can obtain a large visual field range and ensure high imaging quality becomes a problem to be solved at present.

Disclosure of Invention

In view of the above, there is a need to provide an improved optical system for the problem that the conventional wide-angle lens is difficult to balance the small head and the high imaging quality.

An optical system comprising, in order from an object side to an image side along an optical axis:

a first lens having a positive optical power;

a second lens element having a negative optical power, said second lens element having a convex object-side surface at a paraxial region and a convex object-side surface at a peripheral region;

a third lens having optical power;

a fourth lens having a positive optical power;

the optical lens comprises a fifth lens with negative focal power, wherein the object-side surface of the fifth lens is a concave surface at a paraxial region and a concave surface at a peripheral region, both the object-side surface and the image-side surface of the fifth lens are aspheric, and at least one surface of the object-side surface and the image-side surface of the fifth lens comprises at least one inflection point; and the number of the first and second groups,

a sixth lens element having a negative optical power, an object-side surface of the sixth lens element being convex at a paraxial region and convex at a peripherical region;

the optical system satisfies the following relation:

0.24mm^-1＜tan(HFOV)/TTL＜0.34mm^-1；

wherein HFOV denotes a half of a maximum field angle of the optical system, and TTL denotes a distance on an optical axis from an object side surface of the first lens to an imaging surface of the optical system.

According to the optical system, the proper number of lenses are selected and the refractive power and the surface type of each lens are reasonably distributed, so that the imaging analysis capability of the system can be enhanced, the aberration can be effectively corrected, and the definition of an image is ensured; in addition, when the relational expression is satisfied, the field angle is not too large, which is beneficial to the light collection of the system, thereby improving the imaging quality of the system, and meanwhile, the total length of the system is not too large, which is beneficial to the close arrangement of the system structure and the miniaturization.

In one embodiment, the optical system satisfies the following relationship: -13 < f2/f1 < -1; wherein f1 represents the effective focal length of the first lens and f2 represents the effective focal length of the second lens.

When the relational expression is satisfied, the refractive powers of the first lens and the second lens can be reasonably distributed and the lens shapes can be reasonably arranged, so that the field angle of the system can be favorably enlarged. Meanwhile, the positive lens and the negative lens are matched to mutually offset the spherical aberration generated by each other, and when the second lens provides negative refractive power, the spherical aberration generated by the first lens can be corrected, and the field angle of the optical system can be further enlarged.

In one embodiment, the optical system satisfies the following relationship: the HFOV is more than or equal to 45deg and less than or equal to 51 deg; and TTL is less than 4.1 mm.

When the relational expression is satisfied, the characteristics of a large visual angle and a short total length of the optical system can be more specifically shown, and the overlarge field angle can be avoided, so that the situation that the marginal light ray collecting capability of the system is insufficient, the marginal visual field is low in illumination and the imaging quality is reduced is prevented.

In one embodiment, the optical system satisfies the following relationship: 0.25 < ET4/CT4 < 0.4; wherein CT4 represents the thickness of the fourth lens in the optical axis, and ET4 represents the distance in the optical axis direction from the maximum effective aperture of the object-side surface of the fourth lens to the maximum effective aperture of the image-side surface thereof.

When the relational expression is satisfied, the shape and the thickness ratio of the fourth lens can be effectively controlled, so that the forming difficulty of the lens is reduced, the system distortion is effectively corrected, and the imaging quality of the optical system is ensured.

In one embodiment, the optical system satisfies the following relationship:

0.8 < (CT1+ CT2+ CT3)/SD32 < 1.1; wherein CT1 denotes an optical-axis thickness of the first lens, CT2 denotes an optical-axis thickness of the second lens, CT3 denotes an optical-axis thickness of the third lens, and SD32 denotes a maximum effective half aperture of an image-side surface of the third lens.

When the relation is satisfied, the head depth of the system can be increased, so that the head of the system extends out during assembly and can be closer to the screen glass, and the design of a small-head lens module is facilitated; meanwhile, by selecting the ratio of the thickness of the front group lens to the maximum effective half aperture of the third lens, the head aperture of the system is reduced, the screen occupation ratio is improved, and the tolerance and the assembly sensitivity of the optical system are reduced.

In one embodiment, the optical system satisfies the following relationship: -3 < f4/RS8 < -2; wherein f4 represents an effective focal length of the fourth lens, and RS8 represents a radius of curvature of an image side surface of the fourth lens at an optical axis.

When the relation is satisfied, the relation between the effective focal length of the fourth lens and the curvature radius of the image side surface of the fourth lens at the optical axis can be reasonably configured, so that the incident angle of light rays entering the photosensitive element can be effectively controlled, the optical distortion of the system is improved, the system has smaller TV distortion, and the imaging quality is improved.

In one embodiment, the optical system satisfies the following relationship: 1 < RS10/f5 < 8; wherein f5 represents an effective focal length of the fifth lens, and RS10 represents a radius of curvature of an image-side surface of the fifth lens at an optical axis.

When the relational expression is satisfied, the field angle of the system can be effectively enlarged, and simultaneously, the astigmatic aberration of the system can be favorably improved, and the imaging quality of the optical system can be improved.

In one embodiment, the optical system satisfies the following relationship: f6/f5 is more than 0.5 and less than 2; wherein f5 denotes an effective focal length of the fifth lens, and f6 denotes an effective focal length of the sixth lens.

When satisfying above-mentioned relational expression, be favorable to the effective focal length of rational configuration fifth lens and sixth lens to can effectively offset the spherical aberration that the preceding lens group of optical system produced, also be favorable to increasing the optics back focal of system simultaneously, for the photosensitive element provides sufficient matching space, the equipment and the adjustment of the photosensitive element of being convenient for, and then help realizing the incident angle of chief ray on the photosensitive element better and match, promote the formation of image quality.

In one embodiment, the optical system satisfies the following relationship: 1 < vd2-vd3 < 40; wherein vd2 represents the d-ray abbe number of the second lens, and vd3 represents the d-ray abbe number of the third lens.

When the relation is satisfied, the method is favorable for selecting proper lens materials, so that chromatic aberration can be effectively corrected, serious purple fringing phenomenon during system shooting is avoided, the imaging definition of the optical system is improved, and the imaging quality of the optical system is improved.

In one embodiment, the optical system satisfies the following relationship: RS6/RS5 is more than 0.5 and less than 10; wherein RS5 denotes a radius of curvature of an object-side surface of the third lens at an optical axis, and RS6 denotes a radius of curvature of an image-side surface of the third lens at the optical axis.

When the relation is satisfied, the surface shape of the third lens can be effectively controlled, so that when the third lens has negative focal power, the increase of the field angle of the system is facilitated, when the third lens has positive focal power, the first lens can be helped to share partial positive refractive power, the surface shapes of the front and the rear adjacent lenses are compact, the overall surface shape of the system is smooth, the lens arrangement is tighter, the arrangement space of the rear lens group can be reasonably compressed, the total length of the optical system is further shortened, meanwhile, sufficient light focusing can be provided for the rear lens group, and the balance of various aberrations is facilitated while the total length is shortened.

In one embodiment, the optical system satisfies the following relationship: -9.5mm²＜f6*RS11＜-4.5mm²(ii) a Where f6 denotes an effective focal length of the sixth lens, and RS11 denotes a radius of curvature of an object side surface of the sixth lens at an optical axis.

When the relational expression is satisfied, the curvature radius of the object side surface of the sixth lens at the optical axis can be corrected, so that the incident angle of the light rays entering the object side surface of the sixth lens is reduced, and the astigmatic aberration of the system is effectively corrected; meanwhile, stray light can be reduced, and the generation probability of ghost image is reduced; in addition, the surface type of the sixth lens can be effectively controlled, and the problem that the surface type change of the sixth lens greatly affects the arrangement of the lens group is avoided, so that the total length of the optical system is conveniently compressed, and the thinning of the system is realized.

The application also provides an image capturing module.

An image capturing module includes the optical system and a photosensitive element, wherein the photosensitive element is disposed at an image side of the optical system.

Above-mentioned get for instance the module, utilize aforementioned optical system can shoot and obtain the wide, high-quality image of visual angle, get for instance the module simultaneously and still have little head, total length's structural feature, can effectively improve the screen and account for than, make things convenient for the adaptation to the restricted device of size such as cell-phone, flat board, satisfy the market demand better.

The application also provides an electronic device.

An electronic device comprises a shell and the image capturing module, wherein the image capturing module is arranged on the shell.

Above-mentioned electronic device has lightweight characteristics, and utilizes aforementioned getting for instance the module and can realizing that clear big scene scenery shoots, is favorable to promoting user's shooting experience.

Drawings

Fig. 1 shows a schematic structural view of an optical system of embodiment 1 of the present application;

fig. 2 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 1;

fig. 3 is a schematic structural view showing an optical system of embodiment 2 of the present application;

fig. 4 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 2;

fig. 5 is a schematic structural view showing an optical system of embodiment 3 of the present application;

fig. 6 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 3;

fig. 7 is a schematic structural view showing an optical system of embodiment 4 of the present application;

fig. 8 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 4;

fig. 9 is a schematic structural view showing an optical system of embodiment 5 of the present application;

fig. 10 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 5;

fig. 11 is a schematic structural view showing an optical system of embodiment 6 of the present application;

fig. 12 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph, respectively, of the optical system of example 6;

fig. 13 is a schematic diagram illustrating an image capturing module according to an embodiment of the present application;

fig. 14 is a schematic diagram illustrating an electronic device applying an image capturing module according to an embodiment of the disclosure.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical," "horizontal," "left," "right," "upper," "lower," "front," "rear," "circumferential," and the like are based on the orientation or positional relationship shown in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the present description, the expressions first, second, third and the like are used only for distinguishing one feature from another feature, and do not indicate any limitation on the features. Thus, the first lens discussed below may also be referred to as the second lens or the third lens without departing from the teachings of the present application. For ease of illustration, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.

In this specification, a space on a side of the optical element where the object is located is referred to as an object side of the optical element, and correspondingly, a space on a side of the optical element where the object is located is referred to as an image side of the optical element. The surface of each lens closest to the object is called the object side surface, and the surface of each lens closest to the image plane is called the image side surface. And defines the positive direction with distance from the object side to the image side.

In addition, in the following description, if it appears that a lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least near the optical axis; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least at the position near the optical axis. Here, the paraxial region means a region near the optical axis. Specifically, the irregularity of the lens surface region is determined on the image side or the object side by the intersection point of the light ray passing through the region in parallel with the optical axis. For example, when the parallel light passes through the region, the light is focused toward the image side, and the intersection point of the light and the optical axis is located at the image side, the region is a convex surface; on the contrary, if the light ray passes through the region, the light ray is diverged, and the intersection point of the extension line of the light ray and the optical axis is at the object side, the region is a concave surface. In addition, the lens includes an optical axis vicinity region, a circumference vicinity region, and an extension portion for fixing the lens. Ideally, the imaging light does not pass through the extension portion, and therefore the range from the region near the optical axis to the region near the circumference can be defined as the effective aperture range of the lens. The following embodiments omit portions of the extensions for clarity of the drawings. Further, the method of determining the range of the optical axis vicinity region, the circumference vicinity region, or the plurality of regions is as follows:

first, a midpoint is defined as an intersection point of the lens surface and the optical axis, the distance from the midpoint to the boundary of the effective aperture range of the lens is the effective semi-aperture of the lens, and a point of inflection is located on the lens surface and is not located on the optical axis, and a tangent line passing through the point of inflection is perpendicular to the optical axis (i.e. the surface shapes of both sides of the point of inflection on the lens surface are opposite). If there are several points of inflection from the middle point to the outside in the radial direction of the lens, it is the first point of inflection and the second point of inflection in sequence, and the point of inflection farthest from the middle point in the effective aperture range of the lens is the Nth point of inflection. Defining the range between the middle point and the first inflection point as an area near the optical axis, defining the area radially outward of the Nth inflection point as an area near the circumference, and dividing the area between the first inflection point and the Nth inflection point into different areas according to the inflection points; if there is no inflection point on the lens surface, the region near the optical axis is defined as a region corresponding to 0 to 50% of the effective half-aperture, and the region near the circumference is defined as a region corresponding to 50 to 100% of the effective half-aperture.

The features, principles and other aspects of the present application are described in detail below.

Referring to fig. 1, fig. 3, fig. 5, fig. 7, fig. 9 and fig. 11, the present application provides an optical system having a small head and capable of achieving both a wide viewing angle and high imaging quality. The optical system comprises a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element, wherein the six lens elements are sequentially arranged from the first lens element to the sixth lens element along an optical axis from an object side to an image side, and an image plane of the optical system is located at the image side of the sixth lens element. In detail, the six lenses are not jointed, that is, any two adjacent lenses have a space therebetween. Since the process of the cemented lens is more complicated than that of the non-cemented lens, especially the cemented surface of the two lenses needs to have a curved surface with high accuracy so as to achieve high degree of conformity when the two lenses are cemented, and the degree of conformity may be poor due to misalignment during the cementing process, which affects the overall optical imaging quality. Therefore, the six lenses in the optical system of the invention are non-cemented lenses, which can effectively improve the problems generated by cemented lenses.

Specifically, the first lens has positive focal power, so that light rays can be converged into the system and focused on an imaging surface, the total length of the system can be shortened, and the miniaturization of the system can be realized.

The second lens has negative focal power, so that the spherical aberration generated by the first lens can be corrected, and the field angle of the optical system can be further enlarged. Furthermore, the object side surface of the second lens is convex at a position near the optical axis and convex at a position near the circumference, so that light focusing is facilitated, and imaging definition is guaranteed.

The third lens has positive power or negative power. When the third lens has positive power, it can help the first lens to share part of the positive power and can further shorten the total length of the system, and when the third lens has negative power, it can help to enlarge the field angle of the optical system.

The fourth lens has positive focal power, so that the optical distortion of the system can be effectively improved, and the imaging quality of the system is further improved.

The fifth lens has negative focal power, and the object-side surface of the fifth lens is concave at a paraxial region and concave at a peripheral region, so that the system field angle can be enlarged, the spherical aberration of the system can be corrected, the optical back focus of the system can be increased, and the imaging quality of the system can be improved.

Further, the object-side surface and the image-side surface of the fifth lens are both aspheric surfaces. The aspheric lens is characterized in that: the curvature is continuously varied from the lens center to the lens periphery, and the aspherical lens has better imaging characteristics and has an advantage of improving peripheral aberration and astigmatic field curvature, unlike a spherical lens having a constant curvature from the lens center to the lens periphery. By the mode, the flexibility of lens design can be improved, aberration can be effectively corrected, and the imaging quality of the optical system can be improved. Furthermore, at least one surface of the object side surface and the image side surface of the fifth lens comprises at least one inflection point, so that the incidence angle of the chief ray of the off-axis field on the imaging surface is reduced, the response efficiency of the pixel unit of the marginal area of the photosensitive element is improved, the illumination of the marginal field is ensured, the generation of off-axis field aberration is reduced, and the imaging analysis capability of the system is improved.

The sixth lens has negative focal power, and the object side surface of the sixth lens is a convex surface at a position close to the optical axis and a convex surface at a position close to the circumference, so that the sixth lens can be matched with the fifth lens to correct the spherical aberration generated by the front lens group of the system, and simultaneously, the sixth lens is favorable for correcting the astigmatic aberration of the system, reducing stray light and reducing the generation probability of ghost images. In addition, the optical system can be reduced in overall length and reduced in thickness.

Further, the optical system satisfies the following relation: 0.24mm^-1＜tan(HFOV)/TTL＜0.34mm^-1(ii) a Wherein HFOV denotes a half of the maximum field angle of the optical system, and TTL denotes a distance on the optical axis from the object-side surface of the first lens to the imaging surface of the optical system. Further, the half of the maximum field angle in the present application refers to the angle between the light ray incident at the maximum field angle and the optical axis of the system. tan (HFOV)/TTL may be 0.25mm^-1、0.26mm^-1、0.27mm^-1、0.28mm^-1、0.29mm^-1、0.3mm^-1、0.31mm^-1、0.32mm^-1Or 0.33mm^-1. When the relation is satisfied, the field angle is not too large, which is beneficial to the light collection of the system, thereby improving the imaging quality of the system, and meanwhile, the total length of the system is not too large, which is beneficial to the close arrangement of the system structure and realizes the miniaturization. When tan (HFOV)/TTL is lower than the lower limit, the system view angle is too small to meet the shooting requirement, or the total length of the system is too long, which is not beneficial to miniaturization; when tan (hfov)/TTL is higher than the upper limit, the system viewing angle is too large, which tends to result in insufficient light collection capability, thereby reducing the imaging quality.

When the optical system is used for imaging, light rays emitted or reflected by a shot object enter the optical system from the object side direction, sequentially pass through the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens, and finally converge on an imaging surface.

According to the optical system, the imaging analysis capability of the optical system can be enhanced and the aberration can be effectively corrected by selecting a proper number of lenses and reasonably distributing the refractive power and the surface type of each lens, so that the definition of an image is ensured; in addition, when the field angle and the total length of the system meet a specific relationship, the system is favorable for collecting light rays of the system, so that the imaging quality of the system is improved, meanwhile, the total length of the system is not too large, the compact arrangement of the system structure is facilitated, and the miniaturization is realized.

In an exemplary embodiment, the object-side surface and the image-side surface of the first to sixth lenses may each be aspheric. The characteristics of the aspherical lens are described above and will not be described herein. By the mode, the flexibility of lens design can be improved, aberration can be effectively corrected, the imaging quality of the optical system is improved, and the aberration generated in the light transmission process can be better corrected by setting the object side surface and the image side surface of the first lens to the sixth lens to be aspheric surfaces. It should be noted that the surface of each lens may be any combination of a spherical surface and an aspherical surface without departing from the technical solution of the optical system of the present application, and the present application is not limited thereto.

In an exemplary embodiment, the optical system satisfies the following relationship: -13 < f2/f1 < -1; where f1 denotes an effective focal length of the first lens, and f2 denotes an effective focal length of the second lens. f2/f1 can be-12, -11, -9, -7, -6, -5, -4, -3, or-2. When the relational expression is satisfied, the refractive powers of the first lens and the second lens can be reasonably distributed and the lens shapes can be reasonably arranged, so that the field angle of the system can be favorably enlarged. Meanwhile, the positive lens and the negative lens are matched to mutually offset spherical aberration generated by each other, and the second lens provides negative refractive power, so that the spherical aberration generated by the first lens can be corrected, and the field angle of the optical system can be further enlarged. When f2/f1 is lower than the lower limit or higher than the upper limit, the power of the first lens or the second lens is easily beyond a reasonable value, so that the field angle of the system cannot be ensured, extra aberration is easily introduced, and the imaging quality is reduced.

In an exemplary embodiment, the optical system satisfies the following relationship: the HFOV is more than or equal to 45deg and less than or equal to 51 deg; and TTL is less than 4.1 mm. The HFOV may be 45deg, 46deg, 47deg, 48deg, 49deg, 50deg or 51deg, and the TTL may be 3.7mm, 3.8mm, 3.85mm, 3.9mm, 3.95mm or 4.0 mm. By controlling the HFOV and the TTL to meet the relation, the characteristics of a large visual angle and short total length of the optical system can be more specifically shown, meanwhile, the overlarge field angle can be avoided, the low illumination of the edge visual field caused by insufficient edge light collecting capability of the system is prevented, and the imaging quality is reduced.

In an exemplary embodiment, the optical system satisfies the following relationship: 0.25 < ET4/CT4 < 0.4; wherein CT4 denotes the thickness of the fourth lens in the optical axis, and ET4 denotes the distance in the optical axis direction from the maximum effective aperture of the object-side surface of the fourth lens to the maximum effective aperture of the image-side surface thereof. ET4/CT4 may be 0.28, 0.3, 0.32, 0.33, 0.34, 0.35, 0.36, or 0.38. When the relational expression is satisfied, the shape and the thickness ratio of the fourth lens can be effectively controlled, so that the forming difficulty of the lens is reduced, the system distortion is effectively corrected, and the imaging quality of the optical system is ensured. When ET4/CT4 is lower than the lower limit, the thickness of the edge of the fourth lens is too thin, the thickness of the middle part of the fourth lens is too thick, and the lens is difficult to form; when ET4/CT4 is higher than the upper limit, the thickness of the edge of the fourth lens is too thick, and the space for correcting the distortion aberration of the system is insufficient, which affects the imaging quality of the system.

In an exemplary embodiment, the optical system satisfies the following relationship:

0.8 < (CT1+ CT2+ CT3)/SD32 < 1.1; wherein CT1 denotes the thickness of the first lens on the optical axis, CT2 denotes the thickness of the second lens on the optical axis, CT3 denotes the thickness of the third lens on the optical axis, and SD32 denotes the maximum effective half aperture of the image-side surface of the third lens. (CT1+ CT2+ CT3)/SD32 may be 0.85, 0.9, 0.93, 0.95, 1.0, 1.02, or 1.05. When the relation is satisfied, the head depth of the system can be increased, so that the head of the system extends out during assembly and can be closer to the screen glass, and the design of a small-head lens module is facilitated; meanwhile, by selecting the ratio of the thickness of the front group lens to the maximum effective half aperture of the third lens, the head aperture of the system is reduced, the screen occupation ratio is improved, and the tolerance and the assembly sensitivity of the optical system are reduced. When (CT1+ CT2+ CT3)/SD32 is below the lower limit, the thicknesses of the middle portions of the first lens, the second lens, and the third lens are too thin, easily resulting in an increase in the sensitivity of the optical system; when (CT1+ CT2+ CT3)/SD32 is higher than the upper limit, the thicknesses of the middle portions of the first lens, the second lens, and the third lens are too thick, which is disadvantageous for the miniaturization of the optical system.

In an exemplary embodiment, the optical system satisfies the following relationship: -3 < f4/RS8 < -2; where f4 denotes an effective focal length of the fourth lens, and RS8 denotes a radius of curvature of an image-side surface of the fourth lens at the optical axis. f4/RS8 can be-2.9, -2.8, -2.7, -2.6, -2.5, -2.4, -2.3, -2.2, or-2.1. When the relation is satisfied, the relation between the effective focal length of the fourth lens and the curvature radius of the image side surface of the fourth lens at the optical axis can be reasonably configured, so that the incident angle of light rays entering the photosensitive element can be effectively controlled, the optical distortion of the system is improved, the system has smaller TV distortion, and the imaging quality is improved. When f4/RS8 is lower than the lower limit or higher than the upper limit, the refractive power of the fourth lens is too strong or too weak, which is not favorable for controlling the chief ray incident angle of the system, so that the distortion correction is difficult.

In an exemplary embodiment, the optical system satisfies the following relationship: 1 < RS10/f5 < 8; where f5 denotes an effective focal length of the fifth lens, and RS10 denotes a radius of curvature of an image-side surface of the fifth lens at the optical axis. RS10/f5 may be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 2, 4, 6, 7, or 7.5. When the relational expression is satisfied, the field angle of the system can be effectively enlarged, and simultaneously, the astigmatic aberration of the system can be favorably improved, and the imaging quality of the optical system can be improved. When the RS10/f5 is lower than the lower limit, the negative refractive power provided by the fifth lens is insufficient, and the spherical aberration of the system is easily overlarge; when the RS10/f5 is higher than the upper limit, the edge of the fifth lens is excessively bent, so that stray light in the system is increased, and the imaging quality is affected.

In an exemplary embodiment, the optical system satisfies the following relationship: f6/f5 is more than 0.5 and less than 2; wherein f5 denotes an effective focal length of the fifth lens, and f6 denotes an effective focal length of the sixth lens. f6/f5 can be 0.6, 0.8, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, or 1.9. When satisfying above-mentioned relational expression, be favorable to the effective focal length of rational configuration fifth lens and sixth lens to can effectively offset the spherical aberration that the preceding lens group of optical system produced, also be favorable to increasing the optics back focal of system simultaneously, for the photosensitive element provides sufficient matching space, the equipment and the adjustment of the photosensitive element of being convenient for, and then help realizing the incident angle of chief ray on the photosensitive element better and match, promote the formation of image quality. When f6/f5 is lower than the lower limit, the fifth lens has insufficient refractive power and is liable to cause difficulty in spherical aberration correction of the system; when f6/f5 is higher than the upper limit, the refractive power of the fifth lens is too strong, which easily causes the system aberration to be corrected too much, and affects the imaging quality of the system.

In an exemplary embodiment, the optical system satisfies the following relationship: 1 < vd2-vd3 < 40; wherein vd2 represents the d-ray abbe number of the second lens, vd3 represents the d-ray abbe number of the third lens, and d-ray represents yellow light with a wavelength of 587.56 nm. vd2-vd3 can be 2, 2.5, 4, 10, 13, 15, 18, 20, 25, 30, or 35. When the relation is satisfied, the method is favorable for selecting proper lens materials, so that chromatic aberration can be effectively corrected, serious purple fringing phenomenon during system shooting is avoided, the imaging definition of the optical system is improved, and the imaging quality of the optical system is improved.

In an exemplary embodiment, the optical system satisfies the following relationship: RS6/RS5 is more than 0.5 and less than 10; wherein RS5 denotes a radius of curvature of the object-side surface of the third lens at the optical axis, and RS6 denotes a radius of curvature of the image-side surface of the third lens at the optical axis. RS6/RS5 can be 0.7, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, or 9. When the relation is satisfied, the surface shape of the third lens can be effectively controlled, so that when the third lens has negative focal power, the increase of the field angle of the system is facilitated, when the third lens has positive focal power, the surface shapes of the front and rear adjacent lenses are compact, the overall surface shape of the system is smooth, the arrangement of the lenses is tighter, the arrangement space of the rear lens group can be reasonably compressed, the total length of the optical system is further shortened, meanwhile, sufficient light focusing can be provided for the rear lens group, and the balance of various aberrations is facilitated while the total length is shortened. When RS6/RS5 is lower than the lower limit or higher than the upper limit, the image side or the object side of the third lens is easily over-bent, which is not favorable for lens formation, and is easy to cause increased stray light and lower imaging quality.

In an exemplary embodiment, the optical system satisfies the following relationship: -9.5mm²＜f6*RS11＜-4.5mm²(ii) a Where f6 denotes an effective focal length of the sixth lens, and RS11 denotes a radius of curvature of an object side surface of the sixth lens at the optical axis. f6 RS11 may be-9 mm²、-8.5mm²、-8mm²、-7.5mm²、-7mm²、-6.5mm²、-6mm²、-5.5mm²Or-5 mm². When the relational expression is satisfied, the curvature radius of the object side surface of the sixth lens can be corrected, so that the incident angle of light rays entering the object side surface of the sixth lens is reduced, and the astigmatic aberration of the system is effectively corrected; meanwhile, stray light can be reduced, and the generation probability of ghost image is reduced; in addition, the optical system is advantageous in reducing the total length of the optical system and realizing the thinning of the system. When f6 × RS11 is lower than the lower limit or higher than the upper limit, the object-side surface of the sixth lens element is easily over-flat or over-curved, so that the refractive power of the sixth lens element is insufficient or too large, which is not favorable for controlling the incident angle on the object-side surface of the sixth lens element, and the astigmatic aberration of the system cannot be effectively corrected, and the system is also affected by the thinning.

In an exemplary embodiment, a diaphragm is further disposed in the optical system to better control the size of the incident light beam and improve the imaging quality of the optical system. Further, the diaphragm is disposed on the object side of the first lens, or between the first lens and the second lens. Preferably, the diaphragm is an aperture diaphragm. The aperture stop may be located on a surface of the lens (e.g., the object side and the image side) and in operative relationship with the lens, for example, by applying a light blocking coating to the surface of the lens to form the aperture stop at the surface; or the lens is fixedly clamped on the surface of the lens through a clamping piece, and the width of the imaging light beam of the on-axis object point can be limited by the structure of the clamping piece on the surface, so that the aperture stop is formed on the surface.

In an exemplary embodiment, an optical filter is further disposed between the sixth lens and the imaging surface of the optical system, and is used for filtering light rays in a non-working wavelength band, so that a phenomenon of generating false colors or ripples due to interference of light rays in the non-working wavelength band is prevented, and distortion of imaging colors is avoided. Specifically, the filter may be an infrared cut filter, and the material of the filter is glass.

In an exemplary embodiment, each lens in the optical system may be made of glass or plastic, the plastic lens can reduce the weight and production cost of the optical system, and the glass lens can provide the optical system with better temperature tolerance and excellent optical performance. Further, when the optical system is applied to a mobile phone or a tablet, the material of each lens is preferably plastic, so as to reduce the weight of the optical system and reduce the production cost on the premise of satisfying the imaging performance. It should be noted that the material of each lens in the optical system may be any combination of glass and plastic, and is not necessarily all glass or all plastic.

In an exemplary embodiment, the optical system may further include a protective glass. The protective glass is arranged at the image side of the sixth lens or the image side of the optical filter, plays a role in protecting the photosensitive element, and can also prevent the photosensitive element from being polluted and dust falling, thereby further ensuring the imaging quality. When the optical system is applied to an electronic device such as a mobile phone or a tablet, the cover glass may not be provided, so as to further reduce the weight of the electronic device.

The optical system of the above-described embodiment of the present application may employ a plurality of lenses, for example, the six lenses described above. By reasonably distributing the focal length, the refractive power, the surface shape, the thickness, the on-axis distance between the lenses and the like of each lens, the optical system can have the characteristics of large field angle, small overall length and high imaging quality, thereby better meeting the application requirements of electronic equipment such as mobile phones, flat plates and the like. However, it will be understood by those skilled in the art that the number of lenses constituting the optical system may be varied to obtain the respective results and advantages described in the present specification without departing from the technical solutions claimed in the present application.

Specific examples of optical systems that can be applied to the above-described embodiments are further described below with reference to the drawings.

Example 1

An optical system 100 of embodiment 1 of the present application is described below with reference to fig. 1 to 2.

Fig. 1 shows a schematic configuration diagram of an optical system 100 of embodiment 1. As shown in fig. 1, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, and an image plane S15.

The first lens element L1 with positive refractive power has an object-side surface S1 and an image-side surface S2 that are aspheric, wherein the object-side surface S1 is convex at a paraxial region and convex at a paraxial region, and the image-side surface S2 is concave at a paraxial region and concave at a peripheral region.

The second lens element L2 with negative refractive power has an object-side surface S3 and an image-side surface S4 that are aspheric, wherein the object-side surface S3 is convex at a paraxial region and convex at a paraxial region, and the image-side surface S4 is concave at a paraxial region and concave at a peripheral region.

The third lens element L3 with negative refractive power has an object-side surface S5 and an image-side surface S6 that are aspheric, wherein the object-side surface S5 is concave at a paraxial region and concave at a paraxial region, and the image-side surface S6 is convex at a paraxial region and convex at a paraxial region.

The fourth lens element L4 with positive refractive power has an object-side surface S7 and an image-side surface S8 that are aspheric, wherein the object-side surface S7 is concave at a paraxial region and convex at a paraxial region, and the image-side surface S8 is convex at a paraxial region and convex at a paraxial region.

The fifth lens element L5 with negative refractive power has an object-side surface S9 and an image-side surface S10 that are aspheric, wherein the object-side surface S9 is concave at a paraxial region and concave at a paraxial region, and the image-side surface S10 is concave at a paraxial region and convex at a paraxial region.

The sixth lens element L6 with negative refractive power has an object-side surface S11 and an image-side surface S12 that are aspheric, wherein the object-side surface S11 is convex at a paraxial region and convex at a paraxial region, and the image-side surface S12 is concave at a paraxial region and convex at a paraxial region.

Since the object-side surface and the image-side surface of each of the first lens element L1 through the sixth lens element L6 are aspheric, it is advantageous to correct aberrations and solve the problem of image surface distortion, and the optical system 100 can be miniaturized by realizing an excellent optical imaging effect even when the lens elements are small, thin, and flat.

The object side of the first lens L1 is further provided with a stop STO to limit the size of the incident light beam, so as to further improve the imaging quality of the optical system 100. The optical system 100 further includes a filter 110 disposed on the image side of the sixth lens L6 and having an object-side surface S13 and an image-side surface S14. Light from the object OBJ sequentially passes through the respective surfaces S1 to S14 and is finally imaged on the imaging plane S15. The optical filter 110 is used for filtering the light rays in the non-working wavelength band, thereby preventing the phenomenon of generating false color or moire caused by the interference of the light rays in the non-working wavelength band, and avoiding the distortion of the imaging color. Specifically, the filter 110 is an infrared cut filter, and is made of glass.

Table 1 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of the lens of the optical system 100 of example 1, in which the reference wavelengths of the effective focal length, refractive index, and abbe number are 587.56nm, and the unit of the radius of curvature, thickness, and effective focal length of the lens is millimeters (mm). In addition, the first value in the "thickness" parameter column of the lens is the thickness of the lens on the optical axis, and the second value is the distance between the image side surface of the lens and the rear surface of the lens in the image side direction on the optical axis; the numerical value of the stop ST0 in the "thickness" parameter column is the distance on the optical axis from the stop ST0 to the vertex of the next surface (the vertex refers to the intersection point of the surface and the optical axis), and we default that the direction from the object side surface to the image side surface of the last lens of the first lens L1 is the positive direction of the optical axis, when the value is negative, it indicates that the stop ST0 is disposed on the right side of the vertex of the surface, and if the thickness of the stop STO is positive, the stop is on the left side of the vertex of the surface.

TABLE 1

The aspherical surface shape in the lens is defined by the following formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 1); k is a conic coefficient; ai is the ith order coefficient of the aspheric surface. Table 2 below gives the high-order term coefficients a4, a6, A8, a10, a12, a14, a16, a18, and a20 that can be used for the aspherical surfaces S1 to S12 of the lens in example 1.

TABLE 2

The distance TTL on the optical axis from the object-side surface S1 of the first lens L1 to the image forming surface S15 of the optical system 100 is 4.0 mm. As can be seen from the data in tables 1 and 2, the optical system 100 in example 1 satisfies:

tan(HFOV)/TTL＝0.259mm^-1here, HFOV denotes a half of the maximum angle of view of the optical system 100, and TTL denotes a distance on the optical axis from the object side surface S1 of the first lens L1 to the image forming surface S15 of the optical system 100.

f2/f1 is-11.73, where f1 denotes an effective focal length of the first lens L1, and f2 denotes an effective focal length of the second lens L2.

HFOV＝46deg，TTL＝4.0mm。

ET4/CT4 is 0.358, where CT4 denotes the thickness of the fourth lens L4 in the optical axis direction, and ET4 denotes the distance in the optical axis direction from the maximum effective aperture of the object-side surface S7 of the fourth lens L4 to the maximum effective aperture of the image-side surface S8 thereof.

(CT1+ CT2+ CT3)/SD32 is 0.969, where CT1 denotes an optical axial distance of the first lens L1, CT2 denotes an optical axial distance of the second lens L2, CT3 denotes an optical axial distance of the third lens L3, and SD32 denotes a maximum effective half aperture of the image side surface S6 of the third lens L3.

f4/RS8 is-2.215, where f4 denotes an effective focal length of the fourth lens L4, and RS8 denotes a radius of curvature of the image side surface S8 of the fourth lens L4 at a paraxial region.

RS10/f5 is 1.107, where f5 denotes an effective focal length of the fifth lens L5, and RS10 denotes a radius of curvature of the image side surface S10 of the fifth lens L5 at a paraxial region.

f6/f5 is 1.643, where f5 denotes an effective focal length of the fifth lens L5, and f6 denotes an effective focal length of the sixth lens L6.

vd2-vd3 ═ 34.62, where vd2 denotes the d-ray abbe number of the second lens L2, and vd3 denotes the d-ray abbe number of the third lens L3.

RS6/RS5 is 9.448, where RS5 denotes a radius of curvature of the object side surface S5 of the third lens L3 at a paraxial region, and RS6 denotes a radius of curvature of the image side surface S6 of the third lens L3 at a paraxial region.

f6*RS11＝-5.718mm²Where f6 denotes an effective focal length of the sixth lens L6, and RS11 denotes a radius of curvature of the object-side surface S11 of the sixth lens L6 at the paraxial region.

Fig. 2 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph of the optical system 100 of example 1, respectively. Wherein the longitudinal spherical aberration plots show the convergent focus deviations of light rays with wavelengths of 486.13nm, 587.56nm and 656.27nm through the optical system 100; the astigmatism graphs show meridional (T) and sagittal (S) field curvatures of a ray having a wavelength of 587.56nm after passing through the optical system 100; the distortion plot shows the distortion at different image heights for a light ray having a wavelength of 587.56nm passing through the optical system 100. As can be seen from fig. 2, the optical system 100 according to embodiment 1 can achieve good image quality.

Example 2

The optical system 100 of embodiment 2 of the present application is described below with reference to fig. 3 to 4. In this embodiment, a description of parts similar to those of embodiment 1 will be omitted for the sake of brevity.

Fig. 3 shows a schematic configuration of the optical system 100 of embodiment 2. As shown in fig. 3, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, and an image plane S15.

The first lens element L1 with positive refractive power has an object-side surface S1 and an image-side surface S2 that are aspheric, wherein the object-side surface S1 is convex at a paraxial region and convex at a paraxial region, and the image-side surface S2 is concave at a paraxial region and convex at a paraxial region.

The second lens element L2 with negative refractive power has an object-side surface S3 and an image-side surface S4 that are aspheric, wherein the object-side surface S3 is convex at a paraxial region and convex at a paraxial region, and the image-side surface S4 is concave at a paraxial region and convex at a paraxial region.

The third lens element L3 with negative refractive power has an object-side surface S5 and an image-side surface S6 that are aspheric, wherein the object-side surface S5 is concave at a paraxial region and concave at a paraxial region, and the image-side surface S6 is convex at a paraxial region and concave at a paraxial region.

The fourth lens element L4 with positive refractive power has an object-side surface S7 and an image-side surface S8 that are aspheric, wherein the object-side surface S7 is concave at a paraxial region and concave at a paraxial region, and the image-side surface S8 is convex at a paraxial region and convex at a paraxial region.

The first lens L1 to the sixth lens L6 are all made of plastic. The object side of the first lens L1 is further provided with a stop STO to limit the size of the incident light beam, so as to further improve the imaging quality of the optical system 100. The optical system 100 further includes a filter 110 disposed on the image side of the sixth lens L6 and having an object-side surface S13 and an image-side surface S14. Light from the object OBJ sequentially passes through the respective surfaces S1 to S14 and is finally imaged on the imaging plane S15. Specifically, the filter 110 is an infrared cut filter, and is made of glass.

Table 3 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of each lens of the optical system 100 of example 2, where the reference wavelengths of the effective focal length, refractive index, and abbe number are 587.56nm, and the unit of the radius of curvature, thickness, and effective focal length of each lens is millimeters (mm); table 4 shows high-order term coefficients that can be used for the lens aspherical surfaces S1 to S12 in embodiment 2, wherein the aspherical surface type can be defined by formula (1) given in embodiment 1.

TABLE 3

TABLE 4

Fig. 4 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph of the optical system 100 of example 2, respectively. Wherein the longitudinal spherical aberration plots show the convergent focus deviations of light rays with wavelengths of 486.13nm, 587.56nm and 656.27nm through the optical system 100; the astigmatism graphs show meridional (T) and sagittal (S) field curvatures of a ray having a wavelength of 587.56nm after passing through the optical system 100; the distortion plot shows the distortion at different image heights for a light ray having a wavelength of 587.56nm passing through the optical system 100. As can be seen from fig. 4, the optical system 100 according to embodiment 2 can achieve good imaging quality.

Example 3

The optical system 100 of embodiment 3 of the present application is described below with reference to fig. 5 to 6. In this embodiment, a description of parts similar to those of embodiment 1 will be omitted for the sake of brevity.

Fig. 5 shows a schematic configuration diagram of the optical system 100 of embodiment 3. As shown in fig. 5, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, and an image plane S15.

The first lens element L1 with positive refractive power has an object-side surface S1 and an image-side surface S2 that are aspheric, wherein the object-side surface S1 is convex at a paraxial region and convex at a paraxial region, and the image-side surface S2 is convex at a paraxial region and convex at a paraxial region.

The third lens element L3 with positive refractive power has an object-side surface S5 and an image-side surface S6 that are aspheric, wherein the object-side surface S5 is concave at a paraxial region and concave at a paraxial region, and the image-side surface S6 is convex at a paraxial region and concave at a paraxial region.

Table 5 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of each lens of the optical system 100 of example 3, in which the reference wavelengths of the effective focal length, refractive index, and abbe number are 587.56nm, and the unit of the radius of curvature, thickness, and effective focal length of each lens is millimeters (mm); table 6 shows high-order term coefficients that can be used for the lens aspherical surfaces S1 to S12 in embodiment 3, wherein the aspherical surface type can be defined by formula (1) given in embodiment 1.

TABLE 5

TABLE 6

Fig. 6 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph of the optical system 100 of example 3, respectively. Wherein the longitudinal spherical aberration plots show the convergent focus deviations of light rays with wavelengths of 486.13nm, 587.56nm and 656.27nm through the optical system 100; the astigmatism graphs show meridional (T) and sagittal (S) field curvatures of a ray having a wavelength of 587.56nm after passing through the optical system 100; the distortion plot shows the distortion at different image heights for a light ray having a wavelength of 587.56nm passing through the optical system 100. As can be seen from fig. 6, the optical system 100 according to embodiment 3 can achieve good imaging quality.

Example 4

The optical system 100 of embodiment 4 of the present application is described below with reference to fig. 7 to 8. In this embodiment, a description of parts similar to those of embodiment 1 will be omitted for the sake of brevity.

Fig. 7 shows a schematic configuration of an optical system 100 of embodiment 4. As shown in fig. 7, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, and an image plane S15.

Table 7 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of each lens of the optical system 100 of example 4, where the reference wavelengths of the effective focal length, refractive index, and abbe number are 587.56nm, and the unit of the radius of curvature, thickness, and effective focal length of each lens is millimeters (mm); table 8 shows high-order term coefficients that can be used for the lens aspherical surfaces S1 to S12 in example 4, wherein the aspherical surface type can be defined by formula (1) given in example 1.

TABLE 7

TABLE 8

Fig. 8 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph of the optical system 100 of example 4, respectively. Wherein the longitudinal spherical aberration plots show the convergent focus deviations of light rays with wavelengths of 486.13nm, 587.56nm and 656.27nm through the optical system 100; the astigmatism graphs show meridional (T) and sagittal (S) field curvatures of a ray having a wavelength of 587.56nm after passing through the optical system 100; the distortion plot shows the distortion at different image heights for a light ray having a wavelength of 587.56nm passing through the optical system 100. As can be seen from fig. 8, the optical system 100 according to embodiment 4 can achieve good imaging quality.

Example 5

An optical system 100 of embodiment 5 of the present application is described below with reference to fig. 9 to 10. In this embodiment, a description of parts similar to those of embodiment 1 will be omitted for the sake of brevity.

Fig. 9 shows a schematic configuration of an optical system 100 of embodiment 5. As shown in fig. 9, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, and an image plane S15.

The third lens element L3 with positive refractive power has an object-side surface S5 and an image-side surface S6 that are aspheric, wherein the object-side surface S5 is concave at a paraxial region and concave at a paraxial region, and the image-side surface S6 is convex at a paraxial region and convex at a paraxial region.

The first lens L1 to the sixth lens L6 are all made of plastic. A stop STO is further disposed between the first lens L1 and the second lens L2 to limit the size of an incident light beam, and further improve the imaging quality of the optical system 100. The optical system 100 further includes a filter 110 disposed on the image side of the sixth lens L6 and having an object-side surface S13 and an image-side surface S14. Light from the object OBJ sequentially passes through the respective surfaces S1 to S14 and is finally imaged on the imaging plane S15. Specifically, the filter 110 is an infrared cut filter, and is made of glass.

Table 9 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of each lens of the optical system 100 of example 5, in which the reference wavelengths of the effective focal length, refractive index, and abbe number are 587.56nm, and the unit of the radius of curvature, thickness, and effective focal length of each lens is millimeters (mm); table 10 shows high-order term coefficients that can be used for the lens aspherical surfaces S1 to S12 in example 5, wherein the aspherical surface type can be defined by formula (1) given in example 1.

TABLE 9

Watch 10

Fig. 10 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph of the optical system 100 of example 5, respectively. Wherein the longitudinal spherical aberration plots show the convergent focus deviations of light rays with wavelengths of 486.13nm, 587.56nm and 656.27nm through the optical system 100; the astigmatism graphs show meridional (T) and sagittal (S) field curvatures of a ray having a wavelength of 587.56nm after passing through the optical system 100; the distortion plot shows the distortion at different image heights for a light ray having a wavelength of 587.56nm passing through the optical system 100. As can be seen from fig. 10, the optical system 100 according to embodiment 5 can achieve good image quality.

Example 6

An optical system 100 of embodiment 6 of the present application is described below with reference to fig. 11 to 12. In this embodiment, a description of parts similar to those of embodiment 1 will be omitted for the sake of brevity.

Fig. 11 shows a schematic configuration diagram of an optical system 100 of embodiment 6. As shown in fig. 11, the optical system 100 includes, in order from an object side to an image side along an optical axis, a first lens element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, a sixth lens element L6, and an image plane S15.

Table 11 shows the surface type, radius of curvature, thickness, material, refractive index, abbe number (i.e., abbe number), and effective focal length of each lens of the optical system 100 of example 6, in which the reference wavelengths of the effective focal length, refractive index, and abbe number are 587.56nm, and the unit of the radius of curvature, thickness, and effective focal length of each lens is millimeters (mm); table 12 shows high-order term coefficients that can be used for the lens aspherical surfaces S1 to S12 in embodiment 6, wherein the aspherical surface type can be defined by formula (1) given in embodiment 1.

TABLE 11

TABLE 12

Fig. 12 shows a longitudinal spherical aberration graph, an astigmatism graph, and a distortion graph of the optical system 100 of example 6, respectively. Wherein the longitudinal spherical aberration plots show the convergent focus deviations of light rays with wavelengths of 486.13nm, 587.56nm and 656.27nm through the optical system 100; the astigmatism graphs show meridional (T) and sagittal (S) field curvatures of a ray having a wavelength of 587.56nm after passing through the optical system 100; the distortion plot shows the distortion at different image heights for a light ray having a wavelength of 587.56nm passing through the optical system 100. As can be seen from fig. 12, the optical system 100 according to embodiment 6 can achieve good imaging quality.

Table 13 shows the numerical values of the correlation equations of the present invention in the above embodiments.

Watch 13

	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6
							f(mm)	2.87	2.88	2.88	2.75	2.66	2.67
FNO	2.2	2.2	2.2	2.2	2.2	2.4
							HFOV(deg)	46	45.9	45.9	49.3	50.3	50
TTL(mm)	4.0	4.0	3.997	3.948	3.928	3.866
							tan(HFOV)/TTL(mm^-1)	0.259	0.258	0.258	0.294	0.307	0.308
f2/f1	-11.73	-3.23	-2.95	-3.34	-5.91	-5.36
							ET4/CT4	0.358	0.358	0.399	0.286	0.282	0.355
(CT1+CT2+CT3)/SD32	0.969	1.022	1.022	0.954	0.90	0.935
							f4/RS8	-2.215	-2.369	-2.59	-2.41	-2.548	-2.826
RS10/f5	1.107	1.427	1.758	1.706	1.417	7.225
							f6/f5	1.643	1.207	1.075	1.113	1.665	0.761
vd2-vd3	34.62	2.37	2.37	4.26	18.18	13.47
							RS6/RS5	9.448	3.185	0.8	1.601	0.7	0.803
f6*RS11(mm²)	-5.718	-5.649	-5.185	-6.22	-8.08	-7.206

As shown in fig. 13, the present application further provides an image capturing module 200, which includes the optical system 100 (shown in fig. 1) as described above; and a photosensitive element 210, the photosensitive element 210 being disposed on the image side of the optical system 100, a photosensitive surface of the photosensitive element 210 coinciding with the image forming surface S15. Specifically, the photosensitive element 210 may be a Complementary Metal Oxide Semiconductor (CMOS) image sensor or a Charge-coupled Device (CCD) image sensor, and the imaging surface S15 may be a plane or a curved surface with any curvature, especially a curved surface with a concave surface facing the object side, depending on the photosensitive element 210.

In other embodiments, the image capturing module 200 further includes a lens barrel (not shown) for carrying the optical system 100 and a corresponding supporting device (not shown).

In addition, the image capturing module 200 further includes a driving device (not shown) and an image stabilizing module (not shown). The driving device may have an Auto-Focus (Auto-Focus) function, and the driving method may use a driving system such as a Voice Coil Motor (VCM), a Micro Electro-Mechanical Systems (MEMS), a Piezoelectric system (piezo electric), and a Memory metal (Shape Memory Alloy). The driving device can make the optical system 100 obtain a better imaging position, so that the shot object can be shot to obtain a clear image under the state of different object distances; the image stabilization module may be an accelerometer, a gyroscope, or a Hall Effect Sensor. The driving device and the Image stabilizing module together serve as an Optical anti-shake device (OIS), and compensate a blurred Image generated by shaking at the moment of shooting by adjusting the displacement of the Optical axis of the Optical system 100, or provide an Electronic anti-shake function (EIS) by using an Image compensation technology in Image software, so as to further improve the imaging quality of shooting of dynamic and low-illumination scenes.

The image capturing module 200 can capture images with wide viewing angle and high quality by using the optical system 100, and has the structural characteristics of small head and short total length, so that the screen occupation ratio can be effectively improved. The image capturing module 200 can be applied to the fields of mobile phones, automobiles, monitoring, medical treatment and the like. The camera can be used as a mobile phone camera, a vehicle-mounted camera, a monitoring camera or an endoscope and the like, and has a wide market application range.

As shown in fig. 14, the present application further provides an electronic device 300, which includes a housing 310 and the image capturing module 200 as described above, wherein the image capturing module 200 is mounted on the housing 310. Specifically, the image capturing module 200 is disposed in the housing 310 and exposed from the housing 310 to acquire an image, the housing 310 can provide protection for the image capturing module 200, such as dust prevention, water prevention, falling prevention, and the like, and the housing 310 is provided with a hole corresponding to the image capturing module 200, so that light rays penetrate into or out of the housing through the hole.

Above-mentioned electronic device 300 has lightweight characteristics, and utilizes aforementioned module 200 of getting for instance can realize that clear big scene scenery shoots, is favorable to promoting user's shooting experience. In other embodiments, the electronic device 300 is further provided with a corresponding processing system, and the electronic device 300 can transmit the image to the corresponding processing system in time after the image of the object is captured, so that the system can make accurate analysis and judgment.

In other embodiments, the use of "electronic device" may also include, but is not limited to, devices configured to receive or transmit communication signals via a wireline connection and/or via a wireless interface. Electronic devices arranged to communicate over a wireless interface may be referred to as "wireless communication terminals", "wireless terminals", or "mobile terminals". Examples of mobile terminals include, but are not limited to, satellite or cellular telephones; personal Communication System (PCS) terminals that may combine a cellular radiotelephone with data processing, facsimile and data communication capabilities; personal Digital Assistants (PDAs) that may include radiotelephones, pagers, internet/intranet access, Web browsers, notepads, calendars, and/or Global Positioning System (GPS) receivers; and conventional laptop and/or palmtop receivers or other electronic devices that include a radiotelephone transceiver. In addition, the "electronic device" may further include a three-dimensional image capturing device, a digital camera, a tablet computer, a smart television, a network monitoring device, a car recorder, a car backing developing device, a multi-lens device, an identification system, a motion sensing game machine, a wearable device, and the like. The electronic device is only an exemplary embodiment of the present invention, and the application scope of the image capturing module of the present invention is not limited.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. An optical system, in order from an object side to an image side along an optical axis, comprising:

a first lens having a positive optical power;

a third lens having optical power;

a fourth lens having a positive optical power;

the optical system satisfies the following relation:

0.24mm^-1＜tan(HFOV)/TTL＜0.34mm^-1；

2. The optical system according to claim 1, wherein the optical system satisfies the following relation:

-13＜f2/f1＜-1；

wherein f1 represents the effective focal length of the first lens and f2 represents the effective focal length of the second lens.

3. The optical system according to claim 1, wherein the optical system satisfies the following relation:

the HFOV is more than or equal to 45deg and less than or equal to 51 deg; and the number of the first and second electrodes,

TTL＜4.1mm。

4. the optical system according to claim 1, wherein the optical system satisfies the following relation:

0.25＜ET4/CT4＜0.4；

wherein CT4 represents the thickness of the fourth lens in the optical axis, and ET4 represents the distance in the optical axis direction from the maximum effective aperture of the object-side surface of the fourth lens to the maximum effective aperture of the image-side surface thereof.

5. The optical system according to claim 1, wherein the optical system satisfies the following relation:

0.8＜(CT1+CT2+CT3)/SD32＜1.1；

wherein CT1 denotes an optical-axis thickness of the first lens, CT2 denotes an optical-axis thickness of the second lens, CT3 denotes an optical-axis thickness of the third lens, and SD32 denotes a maximum effective half aperture of an image-side surface of the third lens.

6. The optical system according to claim 1, wherein the optical system satisfies the following relation:

-3＜f4/RS8＜-2；

wherein f4 represents an effective focal length of the fourth lens, and RS8 represents a radius of curvature of an image side surface of the fourth lens at an optical axis.

7. The optical system according to claim 1, wherein the optical system satisfies the following relation:

1＜RS10/f5＜8；

wherein f5 represents an effective focal length of the fifth lens, and RS10 represents a radius of curvature of an image-side surface of the fifth lens at an optical axis.

8. The optical system according to claim 1, wherein the optical system satisfies the following relation:

0.5＜f6/f5＜2；

wherein f5 denotes an effective focal length of the fifth lens, and f6 denotes an effective focal length of the sixth lens.

9. The optical system according to claim 1, wherein the optical system satisfies the following relation:

1＜vd2-vd3＜40；

wherein vd2 represents the d-ray abbe number of the second lens, and vd3 represents the d-ray abbe number of the third lens.

10. The optical system according to claim 1, wherein the optical system satisfies the following relation:

0.5＜RS6/RS5＜10；

wherein RS5 denotes a radius of curvature of an object-side surface of the third lens at an optical axis, and RS6 denotes a radius of curvature of an image-side surface of the third lens at the optical axis.

11. The optical system according to claim 1, wherein the optical system satisfies the following relation:

-9.5mm²＜f6*RS11＜-4.5mm²；

where f6 denotes an effective focal length of the sixth lens, and RS11 denotes a radius of curvature of an object side surface of the sixth lens at an optical axis.

12. An image capturing module, comprising the optical system according to any one of claims 1 to 11 and a photosensitive element, wherein the photosensitive element is disposed on an image side of the optical system.

13. An electronic device, comprising a housing and the image capturing module as claimed in claim 12, wherein the image capturing module is mounted on the housing.