Camera Module and Terminal Device

Abstract

A camera module and a terminal device having the camera module, the camera module including a plurality of lenses, where lenses of the plurality of lenses are sequentially arranged from an object side to an image side along a direction of an optical axis, where at least one of the plurality of lenses is a free-form lens, where the free-form lens is a non-rotationally symmetric lens, where a first lens of the plurality of lenses is a lens of the plurality of lenses nearest the object side in a direction from the object side to the image side, where a distance on the optical axis between an object-side surface of the first lens and an imaging surface is TTL, where an effective focal length of the camera module is EFL, and TTL/EFL≤2.0.

Claims

1. A camera module, comprising: a plurality of lenses, wherein lenses of the plurality of lenses are sequentially arranged from an object side to an image side along a direction of an optical axis, wherein at least one of the plurality of lenses is a free-form lens, wherein the free-form lens is a non-rotationally symmetric lens, wherein a first lens of the plurality of lenses is a lens of the plurality of lenses nearest the object side in a direction from the object side to the image side, wherein a distance on the optical axis between an object-side surface of the first lens and an imaging surface is TTL, wherein an effective focal length of the camera module is EFL, and wherein TTL/EFL≤2.0.

2. The camera module according to claim 1, wherein the free-form lens is symmetric with respect to a first plane, and wherein the free-form lens is also symmetric with respect to a second plane; wherein the first plane is a plane comprising an X-axis and the optical axis, wherein the second plane is a plane comprising a Y-axis and the optical axis, and wherein the X-axis and the Y-axis are two central axes that are perpendicular to each other on the imaging surface of the camera module.

3-4. (canceled)

5. The camera module according to claim 2, wherein one or more of an object-side surface or an image-side surface of the free-form lens are free-form surfaces, and wherein a surface type expression of the free-form lens is: $z=\frac{c_x{x}^2+c_y{y}^2}{1+\sqrt{1-\left(1+k_x\right)c_x^2{x}^2-\left(1+k_y\right)c_y^2{y}^2}}+\underset{i=1}{\overset{M}{.Math.}}{A}_i.Math.x^i.Math.+\underset{i=1}{\overset{M}{.Math.}}{B}_i.Math.y^i.Math.$ wherein z is a sag of an optical surface, wherein x is an X-axis coordinate, and y is a Y-axis coordinate, wherein k.sub.x and k.sub.y are conic coefficients, wherein c.sub.x and c.sub.y are curvature radii, and wherein A.sub.i and B.sub.i are polynomial coefficients.

6. The camera module according to claim 2, wherein the X-axis and the Y-axis are each central axes passing through a center of the imaging surface and are respectively parallel to a long side and a short side of the imaging surface.

7. The camera module according to claim 6, wherein a quantity of lenses of the plurality of lenses is N, wherein N≥3, and wherein the plurality of lenses comprise the first lens to the N.sup.th lens sequentially arranged in the direction from the object side to the image side; and wherein surfaces of object-side surfaces and image-side surfaces of the first lens to the (N−1).sup.th lens are all aspheric surfaces, and wherein the N.sup.th lens is a free-form lens.

8. The camera module according to claim 2, wherein a half of a diagonal length of an effective pixel region on the imaging surface of the camera module is ImgH, and wherein TTL/ImgH≤2.0.

9. The camera module according to claim 2, wherein an entrance pupil diameter of the camera module is EPD, and wherein EFL/EPD≤2.2.

10. The camera module according to claim 2, wherein a field of view of the camera module is FOV, wherein FOV≥100 degrees, and wherein EFL<20 mm.

11. The camera module according to claim 1, wherein the quantity of the plurality of lenses is N, wherein three lenses that are of the plurality of lenses and that are nearest the object side are arranged sequentially in the direction from the object side to the image side and are, respectively, the first lens, a second lens, and a third lens; wherein the camera module further comprises a vignetting stop, and wherein the vignetting stop is disposed on an object side of the second lens or on an object side of the third lens.

12. The camera module according to claim 1, wherein a lens of the plurality of lenses adjacent to the imaging surface is the free-form lens, wherein a curvature radius of the object-side surface of the free-form lens is R61, wherein a curvature radius of an image-side surface of the free-form lens is R62, and wherein |EFL/R61|+|EFL/R62|<2.

13. The camera module according to claim 1, further comprising an electronic image sensor, wherein the electronic image sensor is disposed on the imaging surface, and wherein the imaging surface of the camera module is a rectangular region that matches an image sensing area of the electronic image sensor and is not less than the image sensing area of the electronic image sensor.

14. The camera module according to claim 13, wherein a diagonal length of an image sensing surface of the electronic image sensor is not less than 5.5 mm.

15. A terminal device, comprising: a camera-module comprising a plurality of lenses having lenses sequentially arranged from an object side to an image side along a direction of an optical axis, wherein at least one lens of the plurality of lenses is a free-form lens, wherein the free-form lens is a non-rotationally symmetric lens, wherein a first lens of the plurality of lenses is a lens of the plurality of lenses nearest the object side in a direction from the object side to the image side, wherein a distance on the optical axis between an object-side surface of the first lens and an imaging surface is TTL, wherein an effective focal length of the camera module is EFL, and wherein TTL/EFL≤2.0.

16. The terminal device according to claim 15, wherein the free-form lens is symmetric with respect to a first plane, and wherein the free-form lens is symmetric with respect to a second plane; and wherein the first plane is a plane comprising an X-axis and the optical axis, wherein the second plane is a plane comprising a Y-axis and the optical axis, and wherein the X-axis and the Y-axis are each central axes that are perpendicular to each other on the imaging surface of the camera module.

17. A device, comprising: a plurality of lenses having lenses, including a first lens and a free-form lens, sequentially arranged from an object side to an image side along a direction of an optical axis; wherein the free-form lens is spaced apart from the first lens, wherein a first lens of the plurality of lenses is a lens of the plurality of lenses nearest the object side in a direction from the object side to the image side, wherein a distance on the optical axis between an object-side surface of the first lens and an imaging surface is TTL, wherein an effective focal length of the device is EFL, and wherein TTL/EFL≤2.0.

18. The device according to claim 17, wherein the free-form lens is non-rotationally symmetric and is symmetric with respect to a first plane and symmetric with respect to a second plane different from the first plane; wherein the first plane is a plane comprising an X-axis and the optical axis, wherein the second plane is a plane comprising a Y-axis and the optical axis, and wherein the X-axis and the Y-axis are two central axes that are perpendicular to each other on the imaging surface.

19. The device according to claim 18, wherein a quantity of lenses of the plurality of lenses is N, wherein N≥3, and wherein the plurality of lenses comprise the first lens to an N.sup.th lens sequentially arranged in the direction from the object side to the image side; and wherein surfaces of object-side surfaces and image-side surfaces of the first lens to the (N−1).sup.th lens are all aspheric surfaces, and wherein the N.sup.th lens is the free-form lens.

20. The device according to-claim 18, wherein the X-axis and the Y-axis are each central axes passing through a center of the imaging surface and are respectively parallel to a long side and a short side of the imaging surface.

21. The device according to claim 17, wherein a half of a diagonal length of an effective pixel region on the imaging surface of the device is ImgH, and wherein TTL/ImgH≤2.0.

22. The device according to claim 17, wherein a lens of the plurality of lenses adjacent to the imaging surface is the free-form lens, wherein a curvature radius of the object-side surface of the free-form lens is R61, wherein a curvature radius of an image-side surface of the free-form lens is R62, and wherein |EFL/R61|+|EFL/R62|<2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To describe the technical solutions in the embodiments of this application or the background more clearly, the following describes the accompanying drawings required for use in the embodiments of this application or the background.

[0031] FIG. 1 is a schematic diagram of a camera module applied to a terminal device according to this application;

[0032] FIG. 1a is a schematic diagram of a free-form lens that has line symmetry in a direction of an X-axis and in a direction of a Y-axis;

[0033] FIG. 2a and FIG. 2b are schematic diagrams of a camera module according to Embodiment 1 of this application;

[0034] FIG. 2C is a distortion curve of an optical system in Embodiment 1;

[0035] FIG. 2d is a lateral chromatic aberration curve of an optical system in Embodiment 1;

[0036] FIG. 3a and FIG. 3b are schematic diagrams of a camera module according to Embodiment 2 of this application;

[0037] FIG. 3c is a distortion curve of an optical system in Embodiment 2;

[0038] FIG. 3d is a lateral chromatic aberration curve of an optical system in Embodiment 2;

[0039] FIG. 4a and FIG. 4b are schematic diagrams of a camera module according to Embodiment 3 of this application;

[0040] FIG. 4c is a distortion curve of an optical system in Embodiment 3; and

[0041] FIG. 4d is a lateral chromatic aberration curve of an optical system in Embodiment 3.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0042] The following describes the embodiments of this application with reference to the accompanying drawings in the embodiments of this application.

[0043] Refer to FIG. 1. A camera module 10 in this application is applied to a terminal device 100. The terminal device 100 may be a portable terminal such as a mobile phone or a tablet, and the camera module 10 may be an ultra wide-angle lens set. The camera module 10 is assembled inside the terminal device 100, and may be a rear camera or a front camera of the terminal device 100, or a retractable camera that may extend out of a housing of the terminal device 100.

[0044] In an implementation, the camera module provided in this application includes six lenses (six lenses are used as a specific embodiment for description, and a quantity of lenses is not limited in this application). The six lenses are sequentially distributed from an object side to an image side along a direction of an optical axis as follows: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. The quantity of the lenses is not limited to six, and may be another quantity, such as three, four, five, seven. At least one lens of the plurality of lenses is a free-form lens, and the free-form lens is a non-rotationally symmetric surface type. The non-rotationally symmetric free-form lens can increase freedom of optical design of the camera module. A distance on the optical axis between an object-side surface of the first lens and an imaging surface is TTL, an effective focal length of the camera module is EFL, and TTL/EFL≤2.0, to implement relatively short TTL, thereby facilitating a compact structure of the camera module. At least one lens is limited to being a non-rotationally symmetric free-form surface, so that an optical distortion problem of the ultra wide-angle lens set can be alleviated, and the camera module has a compact structure, thereby improving user experience. Aspheric curve equation of lenses 1 to 5 is as follows:

[00006]$z=\frac{c{r}^2}{1+\sqrt{1-\left(1+k\right)c^2{r}^2}}+\underset{i=1}{\overset{M}{.Math.}}{\alpha }_i{\rho }^i$

[0045] z is a sag of an optical surface, and z is an expression of x and y; k is a conic coefficient; c is a curvature radius; r is a radius height in the direction of the optical axis; r.sup.2=x.sup.2+y.sup.2; x is an X-axis coordinate, and y is a Y-axis coordinate; is a polynomial coefficient; and ρ.sub.i is a normalized radial coordinate.

[0046] In this application, a surface type expression (three different surface type expressions are listed below) of the free-form lens is defined, to implement symmetry of the free-form lens in a direction of an X-axis and a direction of a Y-axis. The direction of the X-axis and the direction of the Y-axis are two directions perpendicular to each other on the imaging surface of the camera module.

[0047] In a first implementation, a surface type expression (namely, a free-form sphere curve equation) of the non-rotationally symmetric free-form lens is expressed as follows:

[00007]$z=\frac{c{r}^2}{1+\sqrt{1-\left(1+k\right)c^2{r}^2}}+\underset{i=1}{\overset{M}{.Math.}}{A}_i{E}_i$

[0048] z is a sag of an optical surface, and z is an expression of x and y; k is a conic coefficient; c is a curvature radius; r is a radius height in the direction of the optical axis; r.sup.2=x.sup.2+y.sup.2; A.sub.i is a polynomial coefficient; and E.sub.i is a monomial of an X-axis coordinate and a Y-axis coordinate. Directions of the x-axis and the y-axis herein are consistent with the foregoing directions of the X-axis and the Y-axis about which the free-form lens is symmetric.

[00008]$\underset{i=1}{\overset{N}{.Math.}}{A}_i{E}_i=A_1{x}^0{y}^2+A_2{x}^2{y}^0+A_3{x}^2{y}^2+A_4{x}^4{y}^0+A_5{x}^0{y}^4+A_6{x}^6{y}^0+A_7{x}^0{y}^6+A_8{x}^4{y}^2+A_9{x}^4{y}^2+.Math.$

[0049] A.sub.i is a polynomial coefficient.

[0050] Exponents of x and yin E.sub.i of the surface type expression of the free-form lens are both even numbers, x is an X-axis coordinate, and y is a Y-axis coordinate, so that the surface type of the free-form lens has symmetry.

[0051] In a second implementation, a surface type expression of the free-form lens is:

[00009]$z=\frac{c{r}^2}{1+\sqrt{1-\left(1+k\right)c^2{r}^2}}+\underset{i=1}{\overset{M}{.Math.}}{A}_i{E}_i$

[0052] z is a sag of an optical surface, and z is an expression of x and y; k is a conic coefficient; c is a curvature radius; r is a radius height in the direction of the optical axis; r.sup.2=x.sup.2+y.sup.2; A.sub.i is a polynomial coefficient; and E.sub.i is a monomial of an X-axis coordinate and a Y-axis coordinate.

[00010]$\underset{i=1}{\overset{N}{.Math.}}{A}_i{E}_i=A_1.Math.x^1{y}^0.Math.+A_2.Math.x^0{y}^1.Math.+A_3.Math.x^1{y}^1.Math.+A_4.Math.x^0{y}^2.Math.+A_5.Math.x^3{y}^0.Math.+A_6.Math.x^2{y}^1.Math.+A_7.Math.x^1{y}^2.Math.+A_8.Math.x^0{y}^3.Math.+A_9.Math.x^4{y}^0.Math.+.Math.$

[0053] A.sub.i is a polynomial coefficient, x is an X-axis coordinate, and y is a Y-axis coordinate.

[0054] In a third implementation, a surface type expression of the free-form lens is:

[00011]$z=\frac{c_x{x}^2+c_y{y}^2}{1+\sqrt{1-\left(1+k_x\right)c_x^2{x}^2-\left(1+k_y\right)c_y^2{y}^2}}+\underset{i=1}{\overset{M}{.Math.}}{A}_i.Math.x^i.Math.+\underset{i=1}{\overset{M}{.Math.}}{B}_i.Math.y^i.Math.$

[0055] z is a sag of an optical surface; x is an X-axis coordinate, and y is a Y-axis coordinate; k.sub.x and k.sub.y are conic coefficients; c.sub.x and c.sub.y are curvature radii; and A.sub.i and B.sub.i are polynomial coefficients.

[0056] In the foregoing implementations, the free-form lens may have one surface that is a free-form surface, for example, an object-side surface or an image-side surface is a free-form surface, or both the surfaces may be free-form surfaces, that is, both the object-side surface and the image-side surface are free-form surfaces.

[0057] In an implementation, FIG. 1a is a schematic diagram of a free-form lens that is symmetric in a direction of an X-axis and in a direction of a Y-axis, an imaging surface S14 is a rectangular region, and the X-axis and the Y-axis are two central axes perpendicular to each other on the imaging surface S14. An intersection of the X-axis and the Y-axis is located on an optical axis. Specifically, the direction of the X-axis is a central axis that passes through a center of the rectangular imaging surface S14 and is parallel to a long side of the rectangular imaging surface S14. The direction of the Y-axis is a central axis that passes through the center of the rectangular imaging surface S14 and is parallel to a short side of the rectangular imaging surface S14. The X-axis and the optical axis form a first plane, and the Y-axis and the optical axis form a second plane. The free-form lens L6 is a centrosymmetric structure by using the first plane as a center, and the free-form lens is also a centrosymmetric structure by using the second plane as a center. Keeping the free-form lens L6 centrosymmetric with respect to the first plane and centrosymmetric with respect to the second plane helps ensure imaging quality, and helps implement that imaging quality of a middle region close to the optical axis is better than imaging quality of an edge region away from the optical axis.

[0058] The following describes this application in detail by using three specific embodiments.

Embodiment 1

[0059] As shown in FIG. 2a and FIG. 2b, a straight line in the middle represents an optical axis, a left side of a camera module is an object side, and a right side of the camera module is an image side. In the camera module provided in this embodiment, a first lens L1, a stop STO, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, an infrared filter element IRCF, and an electronic image sensor are sequentially arranged along the optical axis from the object side to the image side. The electronic image sensor may be placed at a position of an imaging surface S14. In this implementation, the stop STO is placed after the first lens L1, and is close to a middle position of the camera module, to help balance an aberration of the camera module.

[0060] The first lens L1 has a positive refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S1 of the first lens L1 is convex. A region, near the optical axis, of an image-side surface S2 of the first lens L1 is convex. Both the regions are aspheric surfaces.

[0061] The second lens L2 has a positive refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S3 of the second lens L2 is convex. A region, near the optical axis, of an image-side surface S4 of the second lens L2 is concave. Both the regions are aspheric surfaces.

[0062] The third lens L3 has a negative refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S5 of the third lens L3 is concave. A region, near the optical axis, of an image-side surface S6 of the third lens L3 is concave. Both the regions are aspheric surfaces.

[0063] The fourth lens L4 has a positive refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S7 of the fourth lens L4 is concave. A region, near the optical axis, of an image-side surface S8 of the fourth lens L4 is concave. Both the regions are aspheric surfaces.

[0064] The fifth lens L5 has a negative refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S9 of the fifth lens L5 is concave. A region, near the optical axis, of an image-side surface S1lo of the fifth lens L5 is concave. Both the regions are aspheric surfaces.

[0065] The sixth lens L6 has a negative refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S11 of the sixth lens L6 is concave. A region, near the optical axis, of an image-side surface S12 of the sixth lens L6 is convex. Both the regions are free-form surfaces.

[0066] An object-side surface S13 and an image-side surface S14 of the infrared filter element IRCF are both flat surfaces.

[0067] In Embodiment 1, a distance on the optical axis between the object-side surface S1 of the first lens L1 and an imaging surface S14 of an infinitely far-away object is TTL, and an effective focal length of the camera module is EFL. The following condition can be met: TTL/EFL≤2.0, to implement shorter TTL, thereby facilitating miniaturization design of the camera module, saving internal space of a terminal device, and facilitating thinning development of the terminal device.

[0068] In Embodiment 1, the exponents of x and yin E.sub.i of the surface type expression of the free-form surface of the sixth lens L6 are both even numbers. This can make the surface type of the lens better symmetric, and facilitate lens processing and detection.

[0069] In an extension of Embodiment 1, optionally, a vignetting stop ST1 (not shown) may be disposed before (namely, on the object side of) the first lens L1, and a vignetting stop ST2 (not shown) may be disposed after (on the image side of) the sixth lens L6, to effectively reduce a diameter of the camera module.

[0070] In Embodiment 1, a focal length of the camera module is f, a curvature radius of the object-side surface S11 of the sixth lens L6 is R61, and a curvature radius of the image-side surface S12 of the sixth lens L6 is R62. The following condition is met: |f/R61|+|f/R62|=1.37, to help correct a comprehensive aberration of a camera set, so that a lateral chromatic aberration of the camera module is less than.sub.3 um and a distortion is less than 2%.

[0071] Table 1a is a table showing characteristics of an optical system in this embodiment. A curvature radius and a thickness are both expressed in millimeters (mm).

TABLE-US-00001 TABLE 1a Surface Surface Curvature Refractive Dispersion number type radius Thickness Material index coefficient S1 Aspheric 5.5545 0.2145 Resin 1.65 22.9 surface S2 Aspheric 43.3006 0.3991 surface STO Flat Infinite 0.0856 surface S3 Aspheric 72.4020 0.8450 Resin 1.54 56 surface S4 Aspheric −2.2277 0.5156 surface S5 Aspheric −4.1395 0.2371 Resin 1.65 22.9 surface S6 Aspheric −6.0243 0.1468 surface S7 Aspheric −12.8096 1.3511 Resin 1.54 56 surface S8 Aspheric −1.5405 0.0811 surface S9 Aspheric −1.3990 0.2261 Resin 1.65 22.9 surface S10 Aspheric −1.7201 0.0691 surface S11 Extended −3.2543 0.5182 Resin 1.65 22.9 aspheric surface S12 Extended 0.5324 1.2303 aspheric surface S13 Flat Infinite 0.2184 Glass 1.52 54.5 surface Flat Infinite 0.0520 surface S14 Flat Infinite 0.0000 surface

[0072] Table 1b gives conic coefficients k and polynomial coefficients a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, and a15 that can be used for aspheric lenses surfaces S1 to S10 in Embodiment 1.

TABLE-US-00002 TABLE 1b Parameter S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 K −89.0714 130.6859 −4655.9692 −0.5553 6.5588 0.9185 45.9472 −0.7741 −0.6498 −0.4395 a1 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 a2 −0.0152 0.2774 0.1147 −0.0006 −0.1417 0.1306 −0.1796 −0.7795 −0.8846 −0.6002 a3 0.3160 0.3257 −0.0143 0.0382 −0.0718 −0.1298 −0.0613 0.2977 0.7433 0.6135 a4 0.1162 −0.2224 −0.1036 −0.7000 −0.1193 0.0432 0.1270 0.4062 0.6841 0.3106 a5 1.3304 1.3382 −0.0501 0.5297 −0.1721 0.1261 −0.3324 0.2381 0.0375 −0.3944 a6 −0.2317 3.3063 −0.0793 −0.6215 −0.1170 0.0307 −0.2253 −0.0309 −0.0484 −0.0173 a7 −1.3109 −0.8758 −0.4983 −0.1927 −0.0370 −0.0910 0.2503 −0.2238 −0.0885 0.0731 a8 0.6204 −11.8832 −0.4727 −0.3596 −0.0438 −0.1312 0.7093 −0.2444 −0.2185 0.1842 a9 −0.8465 −2.1909 0.3526 −1.7055 −0.1584 −0.1027 0.2254 −0.1653 0.0489 0.0459 a10 −0.6141 41.7733 −4.2841 −0.1863 −0.2957 −0.0327 −0.6322 −0.0264 0.1733 −0.0481 a11 3.1749 −7.4454 1.0910 −1.6257 −0.3721 0.0085 −0.1870 0.0887 0.0527 0.0010 a12 5.3311 −45.5026 4.8330 −4.4567 −0.2846 0.0541 −0.1634 0.1337 0.0051 −0.0070 a13 3.6623 33.6188 −0.5357 15.8836 0.0727 0.0683 0.0005 0.1275 −0.0144 −0.0087 a14 −0.9079 85.3587 15.6750 19.4730 0.7811 0.0624 0.2713 0.0584 −0.0541 −0.0043 a15 −12.2109 97.2852 −157.7664 −8.8749 1.9354 0.0098 0.4500 −0.0086 −0.0277 0.0034

[0073] Table 1c gives conic coefficients k and higher-order term coefficients X2Y0, X0Y2, X4Y0, X2Y2, X0Y4, X6Y0, X4Y2, X2Y4, X0Y6, X8Y0, X6Y2, X4Y4, X2Y6, and X0Y8 that can be used for the free-form surfaces S11 and S12 in Embodiment 1.

TABLE-US-00003 TABLE 1c Parameter S11 S12 K −0.2054 −1.4469 X2Y0 1.7232 −1.0737 X0Y2 1.7480 −1.0137 X4Y0 −1.5261 0.0639 X2Y2 −3.0799 −0.0764 X0Y4 −1.4951 −0.0559 X6Y0 1.1911 −0.0397 X4Y2 3.4068 0.2676 X2Y4 3.0357 0.3088 X0Y6 0.8664 0.0968 X8Y0 −0.7572 0.0372 X6Y2 −2.6574 −0.1552 X4Y4 −2.2974 −0.2318 X2Y6 −1.3632 −0.2295 X0Y8 −0.1705 −0.0414

[0074] FIG. 2C shows a distortion curve of the optical system in Embodiment 1, which represents distortion values corresponding to different fields of view.

[0075] FIG. 2d shows a lateral chromatic aberration curve of the optical system in Embodiment 1, which represents lateral chromatic aberration values corresponding to five different wavelengths of light at different fields of view. Arrow indication lines are used to represent the five different wavelengths of light. The wavelengths are 510 nanometers, 470 nanometers, 610 nanometers, 550 nanometers, and 650 nanometers, respectively.

[0076] It can be learned from FIG. 2c and FIG. 2d that the optical system provided in Embodiment 1 can achieve good imaging quality.

Embodiment 2

[0077] As shown in FIG. 3a and FIG. 3b, in a camera module in this implementation, a first lens L1, a second lens L2, a stop STO, a third lens L3, a fourth lens L4, and a fifth lens L5, a sixth lens L6, an infrared filter element IRCF, and an electronic image sensor are sequentially arranged along an optical axis from an object side to an image side. The electronic image sensor can be placed on a position of an imaging surface S14 (also referred to as an image surface). In this implementation, the stop STO is placed after the second lens L2, and is close to a middle position of the camera module, to help balance an aberration of the camera module.

[0078] The first lens L1 has a positive refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S1 of the first lens L1 is concave. A region, near the optical axis, of an image-side surface S2 of the first lens L1 is convex. Both the regions are aspheric surfaces.

[0079] The second lens L2 has a negative refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S3 of the second lens L2 is convex. A region, near the optical axis, of an image-side surface S4 of the second lens L2 is convex. Both the regions are aspheric surfaces.

[0080] The third lens L3 has a positive refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S5 of the third lens L3 is convex. A region, near the optical axis, of an image-side surface S6 of the third lens L3 is concave. Both the regions are aspheric surfaces.

[0081] The fourth lens L4 has a positive refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S7 of the fourth lens L4 is concave. A region, near the optical axis, of an image-side surface S8 of the fourth lens L4 is concave. Both the regions are aspheric surfaces.

[0082] The fifth lens L5 has a negative refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S9 of the fifth lens L5 is concave. A region, near the optical axis, of an image-side surface S110 of the fifth lens L5 is concave. Both the regions are aspheric surfaces.

[0083] The sixth lens L6 has a negative refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S11 of the sixth lens L6 is concave. A region, near the optical axis, of an image-side surface S12 of the sixth lens L6 is convex. Both the regions are free-form surfaces.

[0084] In Embodiment 2, a distance on the optical axis between the object-side surface S1 of the first lens L1 and an imaging surface S14 of an infinitely far-away object is TTL, and an effective focal length of the camera module is EFL. The following condition can be met: TTL/EFL≤2, to implement shorter TTL, thereby facilitating miniaturization design of the camera module, saving internal space of a terminal device, and facilitating thinning development of the terminal device.

[0085] In Embodiment 2, the exponents of x and yin E.sub.i of the surface type expression of the free-form surface of the sixth lens L6 are both even numbers. This can make the surface type of the lens better symmetric, and facilitate lens processing and detection.

[0086] In an extension of Embodiment 2, optionally, a vignetting stop ST1 (not shown) may be disposed before (namely, on the object side of) the first lens L1, and a vignetting stop ST2 (not shown) may be disposed after (on the image side of) the sixth lens L6, to effectively reduce a diameter of the camera module.

[0087] In Embodiment 2, a focal length of the camera module is f, a curvature radius of the object-side surface S11 of the sixth lens L6 is R61, and a curvature radius of the image-side surface S12 of the sixth lens L6 is R62. The following condition is met: |f/R61|+|f/R62|=0.71, to help correct a comprehensive aberration of a camera set, so that a lateral chromatic aberration of the camera module is less than 3 um and a distortion is less than 2%.

[0088] Table 2a is a table showing characteristics of an optical system in this embodiment. A curvature radius and a thickness are both expressed in millimeters (mm).

TABLE-US-00004 TABLE 2a Surface Surface Curvature Refractive Dispersion number type radius Thickness Material index coefficient Material S1 Aspheric −2.3847 0.3458 Resin 1.65 22.9 EP7000 surface S2 Aspheric 1.8127 0.0363 surface S3 Aspheric 1.458 0.2855 Resin 1.67 19.243 EP9000 surface S4 Aspheric 3.0075 0.5178 surface STO Flat Infinite −0.0091 surface S5 Aspheric 47.486 0.7245 Resin 1.54 55.99 APL5014CL surface S6 Aspheric −2.3808 0.6004 surface S7 Aspheric −7.4388 0.9962 Resin 1.54 55.99 APL5014CL surface S8 Aspheric −1.4872 0.096 surface S9 Aspheric −1.0653 0.2928 Resin 1.67 19.243 EP9000 surface S10 Aspheric −1.6155 0.0363 surface S11 Extended −0.2474 0.9056 Resin 1.65 22.9 EP7000 aspheric surface S12 Extended 1.6942 1.2628 aspheric surface S13 Flat Infinite 0.2096 Glass 1.52 54.5 D263T surface Flat Infinite 0.0499 surface S14 Flat Infinite 0 surface

[0089] Table 2b gives conic coefficients k and polynomial coefficients a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, and a15 that can be used for aspheric lenses surfaces S1 to S10 in Embodiment 2.

TABLE-US-00005 TABLE 2b Parameter S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 K −20.2834 −2.3818 −6.3801 −57.3023 −100.0000 0.3347 23.0097 −0.5407 −0.6057 −0.7241 a1 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 a2 0.3807 −1.1425 −0.0770 0.6250 0.1903 0.1292 −0.4347 −0.8528 −0.9073 −0.5643 a3 0.0540 1.0089 0.8594 0.2524 0.0154 0.0458 0.2969 1.1047 1.4486 0.3965 a4 0.2938 −0.0461 −0.9054 −0.1618 −0.1345 −0.4954 −0.5458 −0.2717 0.7216 0.8305 a5 −0.0688 −0.0713 0.6027 −0.0884 0.0204 0.6727 −0.1883 0.1518 −0.3589 −0.5759 a6 −0.0549 −0.3815 −0.8218 1.7311 0.0268 −0.9452 0.2630 0.0884 −0.0851 −0.2502 a7 −0.0334 0.3001 −1.0009 −3.0152 −0.3675 −0.5039 0.3214 −0.1407 −0.1323 0.0253 a8 0.0225 0.3473 1.0333 −8.5801 −0.5188 1.2010 0.5801 −0.3391 −0.1651 0.2075 a9 0.0821 −0.3709 −0.5461 −0.0307 0.4198 0.1419 0.0467 −0.2976 −0.0121 0.1278 a10 0.0606 0.1619 −0.6811 47.1165 −3.5227 0.0874 −0.7888 −0.1074 −0.0245 0.0155 a11 −0.0499 −0.1433 1.7402 −1.9290 3.3752 −5.1732 −0.3589 −0.0821 −0.0951 0.0291 a12 −0.0466 −0.0746 1.4197 −54.5390 10.0663 −10.3682 −0.1919 −0.0458 −0.0297 −0.0061 a13 −0.0083 0.0858 1.4019 −16.3711 10.5950 13.9387 −0.3328 −0.1357 −0.0921 −0.0237 a14 0.0474 −0.2141 −0.1854 −50.7892 −12.5135 25.7124 0.5221 −0.0465 0.3056 −0.0251 a15 0.0322 −0.2401 −1.3685 15.2032 −156.0708 9.4206 0.7632 0.2883 0.4513 −0.0132 a16 −0.0819 0.4074 −2.0867 193.8807 170.3787 −57.1594 1.0040 0.9630 0.3100 0.0046

[0090] Table 2C gives conic coefficients k and higher-order term coefficients X2Y0, X0Y2, X4Y0, X2Y2, X0Y4, X6Y0, X4Y2, X2Y4, X0Y6, X8Y0, X6Y2, X4Y4, X2Y6, and X0Y8 that can be used for the free-form surfaces S11 and S12 in Embodiment 2.

TABLE-US-00006 TABLE 2c Parameter S11 S12 K −1.0178 −4.3499 X2Y0 6.5795 0.0633 X0Y2 6.5725 0.0489 X4Y0 −1.725 −0.2768 X2Y2 −3.4771 −0.5611 X0Y4 −1.7136 −0.2535 X6Y0 0.4593 0.1003 X4Y2 1.6453 0.4314 X2Y4 1.527 0.3351 X0Y6 0.4794 0.0951 X8Y0 0.1257 0.0157 X6Y2 −0.2977 −0.2672 X4Y4 0.028 −0.1712 X2Y6 −0.0265 −0.1196 X0Y8 0.0337 −0.0193

[0091] FIG. 3c shows a distortion curve of the optical system in Embodiment 2, which represents distortion values corresponding to different fields of view.

[0092] FIG. 3d shows a lateral chromatic aberration curve of the optical system in Embodiment 2, which represents lateral chromatic aberration values corresponding to five different wavelengths of light at different fields of view. Arrow indication lines are used to represent the five different wavelengths of light. The wavelengths are 510 nanometers, 470 nanometers, 610 nanometers, 550 nanometers, and 650 nanometers, respectively.

[0093] It can be learned from FIG. 3c and FIG. 3d that the optical system provided in Embodiment 2 can achieve good imaging quality.

Embodiment 3

[0094] As shown in FIG. 4a and FIG. 4b, in a camera module in this implementation, a first lens L1, a second lens L2, a stop STO, a third lens L3, a fourth lens L4, and a fifth lens L5, a sixth lens L6, an infrared filter element IRCF, and an electronic image sensor are sequentially arranged along an optical axis from an object side to an image side. The electronic image sensor can be placed on a position of an imaging surface S14.

[0095] The first lens L1 has a positive refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S1 of the first lens L1 is concave. A region, near the optical axis, of an image-side surface S2 of the first lens L1 is convex. Both the regions are aspheric surfaces.

[0096] The second lens L2 has a negative refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S3 of the second lens L2 is convex. A region, near the optical axis, of an image-side surface S4 of the second lens L2 is convex. Both the regions are aspheric surfaces.

[0097] The third lens L3 has a positive refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S5 of the third lens L3 is convex. A region, near the optical axis, of an image-side surface S6 of the third lens L3 is concave. Both the regions are aspheric surfaces.

[0098] The fourth lens L4 has a positive refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S7 of the fourth lens L4 is concave. A region, near the optical axis, of an image-side surface S8 of the fourth lens L4 is concave. Both the regions are aspheric surfaces.

[0099] The fifth lens L5 has a negative refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S9 of the fifth lens L5 is concave. A region, near the optical axis, of an image-side surface S110 of the fifth lens L5 is concave. Both the regions are aspheric surfaces.

[0100] The sixth lens L6 has a negative refractive power and is made of a resin material. A region, near the optical axis, of an object-side surface S11 of the sixth lens L6 is concave. A region, near the optical axis, of an image-side surface S12 of the sixth lens L6 is convex. Both the regions are free-form surfaces.

[0101] In Embodiment 3, a distance on the optical axis between the object-side surface S1 of the first lens L1 and an imaging surface S14 of an infinitely far-away object is TTL, and an effective focal length of the camera module is EFL. The following condition can be met: TTL/EFL≤2, to implement shorter TTL, thereby facilitating miniaturization design of the camera module, saving internal space of a terminal device, and facilitating thinning development of the terminal device.

[0102] In Embodiment 3, the exponents of x and y in E.sub.i of the surface type expression of the free-form surface of the sixth lens L6 are both even numbers, which makes the surface type of the lens better symmetric, and facilitates lens processing and detection.

[0103] In an extension of Embodiment 3, optionally, a vignetting stop ST1 (not shown) may be disposed before (namely, on the object side of) the first lens L1, and a vignetting stop ST2 (not shown) may be disposed after (on the image side of) the sixth lens L6, to effectively reduce a diameter of the camera module.

[0104] In Embodiment 3, a focal length of the camera module is f, a curvature radius of the object-side surface S11 of the sixth lens L6 is R61, and a curvature radius of the image-side surface S12 of the sixth lens L6 is R62. The following condition is met: |f/R61|+|f/R62|=1.92, to help correct a comprehensive aberration of a camera set, so that a lateral chromatic aberration of the camera module is less than 3 um and a distortion is less than 2%.

[0105] Table 3a is a table showing characteristics of an optical system in this embodiment. A curvature radius and a thickness are both expressed in millimeters (mm).

TABLE-US-00007 TABLE 3a Surface Surface Curvature Refractive Dispersion number type radius Thickness Material index coefficient Material S1 Aspheric −3.1589 0.2953 Resin 1.65 22.9 EP7000 surface S2 Aspheric 3.5364 0.0237 surface S3 Aspheric 1.7330 0.2483 Resin 1.65 22.9 EP7000 surface S4 Aspheric 3.3108 0.4889 surface STO Flat Infinite 0.0136 surface S5 Aspheric 19.8218 0.4821 Resin 1.54 56 APL5014CL surface S6 Aspheric −2.5251 0.7337 surface S7 Aspheric −10.0889 1.3051 Resin 1.54 56 APL5014CL surface S8 Aspheric −1.5229 0.0760 surface S9 Aspheric −1.4148 0.2782 Resin 1.65 22.9 EP7000 surface S10 Aspheric −1.9785 0.0500 surface S11 Extended −2.2632 0.7622 Resin 1.65 22.9 EP7000 aspheric surface S12 Extended 0.8529 1.0613 aspheric surface S13 Flat Infinite 0.2100 Glass 1.52 54.5 D263T surface Flat Infinite 0.0500 surface S14 Flat Infinite 0.0000 surface

[0106] Table 3b gives conic coefficients k and polynomial coefficients a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, and a15 that can be used for aspheric lenses surfaces S1 to S10 in Embodiment 3.

TABLE-US-00008 TABLE 3b Parameter S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 K −19.1982 −6.7071 −10.5697 −94.8320 −92.1353 −1.8945 39.5657 −0.6213 −0.6096 −0.5025 a1 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 a2 0.0956 −0.9439 −0.1502 0.4913 0.0435 0.1196 −0.1316 −0.3738 −0.6654 −0.5632 a3 0.1720 0.6845 0.5477 0.2394 0.0128 0.0550 −0.0684 0.1254 0.8416 0.6787 a4 0.0986 0.1394 −0.5466 −0.6546 −0.0759 −0.5139 0.2599 0.3174 0.5371 −0.0965 a5 −0.1024 −0.0329 0.8873 0.4402 0.0738 0.4193 −0.3706 0.5159 −0.4902 −0.4410 a6 −0.0022 −0.5623 −0.1384 2.7731 0.0413 −0.6119 −0.1841 0.0359 −0.1847 −0.0280 a7 −0.0098 0.1792 −0.9765 0.4146 −0.4024 0.2886 0.2694 −0.3266 0.0420 0.0990 a8 −0.0333 0.3229 0.6770 −9.6616 −0.2291 0.4303 0.6533 −0.3749 −0.0774 0.2199 a9 0.0279 −0.2649 −1.2748 −1.5490 0.6105 −1.1976 0.1466 −0.2612 0.0200 0.0806 a10 0.0284 0.2324 −1.1899 32.7032 −2.3182 −0.8407 −0.6587 −0.0882 0.0473 −0.0266 a11 −0.0325 −0.1094 1.5365 −15.6447 3.9257 −3.4558 −0.2067 0.0396 −0.0928 0.0011 a12 −0.0176 −0.1524 2.5773 −61.9447 7.7852 −5.5869 −0.1438 0.0833 −0.0936 −0.0157 a13 0.0005 0.1188 1.7996 17.9166 −0.9105 15.6206 0.1141 0.0908 −0.0681 −0.0193 a14 0.0203 0.0183 −0.9110 88.2484 7.6825 24.6383 0.3079 0.0386 −0.0172 −0.0141 a15 0.0196 0.0024 −2.7400 131.1438 −159.2654 2.0639 0.4387 0.0331 0.0679 −0.0040 a16 −0.0192 −0.0171 −1.9357 −227.7872 166.8148 −66.9990 −0.4919 0.0731 0.1369 0.0094

[0107] Table 3c gives conic coefficients k and higher-order term coefficients X2Y0, X0Y2, X4Y0, X2Y2, X0Y4, X6Y0, X4Y2, X2Y4, X0Y6, X8Y0, X6Y2, X4Y4, X2Y6, and X0Y8 that can be used for the free-form surfaces S11 and S12 in Embodiment 3.

TABLE-US-00009 TABLE 3c Parameter S11 S12 K −0.7265 −2.3120 X2Y0 1.2459 −0.4049 X0Y2 1.2611 −0.3527 X4Y0 −1.2282 −0.1014 X2Y2 −2.5043 −0.4262 X0Y4 −1.1911 −0.1977 X6Y0 0.9985 0.0226 X4Y2 2.8791 0.3820 X2Y4 2.6747 0.4401 X0Y6 0.7212 0.1124 X8Y0 −0.5561 0.0280 X6Y2 −1.7777 −0.1859 X4Y4 −1.6110 −0.1588 X2Y6 −0.9485 −0.1983 X0Y8 −0.0621 −0.0308

[0108] FIG. 4C shows a distortion curve of the optical system in Embodiment 3, which represents distortion values corresponding to different fields of view.

[0109] FIG. 4d shows a lateral chromatic aberration curve of the optical system in Embodiment 3, which represents lateral chromatic aberration values corresponding to five different wavelengths of light at different fields of view. Arrow indication lines are used to represent the five different wavelengths of light. The wavelengths are 510 nanometers, 470 nanometers, 610 nanometers, 550 nanometers, and 650 nanometers, respectively.

[0110] It can be learned from FIG. 4c and FIG. 4d that the optical system provided in Embodiment 3 can achieve good imaging quality.

[0111] Example embodiments of this application are described above. It should be noted that a person of ordinary skill in the art may further make several improvements and modifications without departing from the principle of this application, and these improvements and modifications are also considered to be within the protection scope of this application.