An optical imaging lens

Abstract

The present invention belongs to the field of optical imaging technology. An optical imaging lens includes, from the object side to the image side, in order: an aperture; a first lens with positive refractive power, whose object side surface is convex at the near optical axis, and whose image side surface is concave at the near optical axis; a second lens with positive refractive power, whose object side surface is concave at the near optical axis, and whose image side surface is convex at the near optical axis; a third lens with refractive power, whose object side surface is convex at the near optical axis, and whose image side surface is concave at the near optical axis; the imaging lens satisfies the following relationship: ∑CT / ImgH<0.6, (SAG12+SAG21) / f<0.6. The present invention can still maintain good optical performance under the condition of reducing the overall volume of the lens.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical imaging, and in particular relates to an optical imaging lens. Background Art

[0002] With the rapid development of science and technology, especially electronic technology, mobile and lightweight electronic devices have been rapidly popularized, driving the rapid development of imaging module-related technologies used in electronic devices. Image modules have been used more and more widely, such as in smartphones, tablets, driving recorders, and sports cameras, and the trend of thinning and lightweight electronic products such as smartphones has also led to an increasing demand for miniaturization of image modules. With the advancement of semiconductor manufacturing process technology, the pixel size of photosensitive devices has been reduced, and the optical imaging lens loaded in the imaging module also needs to be shortened accordingly. Traditional thin and light optical imaging lenses mostly use four-piece and five-piece lens structures, but the four-piece and five-piece lens structures have limitations in terms of refractive power distribution, aberration and astigmatism correction, and sensitivity distribution, and cannot further meet the imaging requirements of large aperture and high pixels. Therefore, how to effectively compress the total length of the optical imaging lens while taking into account good imaging quality is a problem that technicians in this field need to solve urgently. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an optical imaging lens which can still maintain good optical performance under the condition of reducing the overall volume of the lens.

[0004] The technical solution of the present invention is as follows:

[0005] An optical imaging lens comprises, from the object side to the image side, an aperture; a first lens with positive refractive power, whose object side surface is convex at the near optical axis, and whose image side surface is concave at the near optical axis; a second lens with positive refractive power, whose object side surface is concave at the near optical axis, and whose image side surface is convex at the near optical axis; a third lens with refractive power, whose object side surface is convex at the near optical axis, and whose image side surface is concave at the near optical axis; the imaging lens satisfies the following relationship: ∑CT / ImgH<0. 6, (SAG12+SAG21) / f<0.6; wherein, ∑CT is the sum of the center thicknesses of all lenses on the optical axis, ImgH is half of the diagonal length of the effective imaging area of ​​the imaging lens, SAG12 is the axial distance between the intersection of the object side surface of the first lens and the optical axis to the vertex of the effective radius of the object side surface of the first lens, SAG21 is the axial distance between the intersection of the image side surface of the second lens and the optical axis to the vertex of the effective radius of the image side surface of the second lens, and f is the focal length of the lens group.

[0006] Furthermore, the imaging lens satisfies the relationship: 2.3<(CT1 / ET1)+(CT2 / ET2)+(CT3 / ET3)<3.6; wherein CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, CT3 is the center thickness of the third lens on the optical axis, ET1 is the edge thickness of the first lens, ET2 is the edge thickness of the second lens, and ET3 is the edge thickness of the third lens.

[0007] Furthermore, the imaging lens satisfies the relationship: |(L2R1-L2R2) / f2|<0.1; wherein L2R1 is the curvature radius of the image side of the second lens, L2R2 is the curvature radius of the object side of the second lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

[0008] Furthermore, the imaging lens satisfies the relationship: f / (f3-f2)<0.5; wherein f is the focal length of the lens group, f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

[0009] Furthermore, the imaging lens satisfies the relationship: FNO<2.5, wherein FNO is the relative aperture of the lens group.

[0010] Furthermore, the imaging lens satisfies the relationship: 0.3<BFL / ImgH<0.6; wherein BFL is the distance from the image side of the third lens to the imaging surface of the lens group on the optical axis, and ImgH is half of the diagonal length of the effective imaging area of ​​the imaging lens.

[0011] Furthermore, the imaging lens satisfies the relationship: CT2 / ΣCT>0.3; wherein CT2 is the center thickness of the second lens on the optical axis, and ΣCT is the sum of the center thicknesses of all lenses on the optical axis.

[0012] Furthermore, the imaging lens satisfies the relationship: OTTL / f1<1; wherein OTTL is the distance from the front end of the first lens to the imaging surface, and f1 is the focal length of the first lens.

[0013] Furthermore, the imaging lens satisfies the relationship: 0.45<sin 2 (Semi-FOV)<0.5; where Semi-FOV is half of the maximum field of view of the imaging lens.

[0014] Furthermore, the object-side surface and the image-side surface of the first lens, the second lens and the third lens are all aspherical surfaces.

[0015] Compared with the prior art, the present invention has the following beneficial effects: adopting a three-piece structure, the optical system of this structure can improve optical performance by improving phase difference, reduce the tolerance sensitivity of the lens, and make the lens have better light focusing ability, while reducing the volume of the lens head and the depth of viewpoint, it can still maintain good optical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the structure of an imaging lens according to a first embodiment of the present invention;

[0017] Figure 2 is a graph showing astigmatism and distortion of the imaging lens according to the first embodiment of the present invention;

[0018] Figure 3 is a spot diagram of the imaging lens according to the first embodiment of the present invention;

[0019] Figure 4 Schematic diagram of the structure of an imaging lens according to a second embodiment of the present invention;

[0020] Figure 5 is a graph showing astigmatism and distortion of the imaging lens according to the second embodiment of the present invention;

[0021] Figure 6 is a spot diagram of an imaging lens according to a second embodiment of the present invention;

[0022] Figure 7 Schematic diagram of the structure of an imaging lens according to a third embodiment of the present invention;

[0023] Figure 8 is a graph showing astigmatism and distortion of the imaging lens according to the third embodiment of the present invention;

[0024] Fig. 9 is a spot diagram of an imaging lens according to a third embodiment of the present invention;

[0025] Fig.10 is a schematic structural diagram of an imaging lens according to a fourth embodiment of the present invention;

[0026] Fig.11 is a graph showing astigmatism and distortion of the imaging lens according to the fourth embodiment of the present invention;

[0027] Fig.12 is a spot diagram of an imaging lens according to a fourth embodiment of the present invention;

[0028] Fig.13 is a schematic structural diagram of an imaging lens according to a fifth embodiment of the present invention;

[0029] Fig.14 is a graph showing astigmatism and distortion of the imaging lens according to the fifth embodiment of the present invention;

[0030] Fig.15is a spot diagram of an imaging lens according to a fifth embodiment of the present invention;

[0031] Fig.16 is a schematic structural diagram of an imaging lens according to a sixth embodiment of the present invention;

[0032] Fig.17 is a graph showing astigmatism and distortion of the imaging lens according to the sixth embodiment of the present invention;

[0033] Fig.18 FIG. 4 is a spot diagram of an imaging lens according to a sixth embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The drawings show preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

[0035] In the description of the present invention, the object side refers to the side of the lens facing the subject, and the image side refers to the side of the lens facing the imaging surface. When a section is made at any point on the object side surface of the lens, the object side surface is always located on the image side of the section, and its curvature radius is positive, then the object side surface of the lens is convex; otherwise, the object side surface of the lens is concave.

[0036] When a section is made at any point on the image side surface of the lens, the image side surface is always on the object side of the section, and its radius of curvature is negative, then the image side surface of the lens is convex; otherwise, the image side surface of the lens is concave.

[0037] If a section is made at any point on the object side surface or image side surface of the lens, and the surface has part on the image side of the section and part on the object side of the section, then there is an inflection point on the surface. The above method still applies to judging the convexity of the object side and image side surfaces near the optical axis.

[0038] In addition, the aspheric curve equation of each lens is expressed as follows:

[0039]

[0040] Wherein, Z is the distance vector height from the origin of the aspheric surface when the aspheric surface is at a height of r along the optical axis direction, c is the paraxial curvature of the aspheric surface (radius of curvature R = 1 / c, i.e., the inverse of the curvature); k is the cone coefficient; Ai is the i-th order coefficient of the aspheric surface, and the high-order coefficients used in the present invention are A4, A6, A8, A 10 , A 12 , A 14 , A 16 , A 18 , A 20 .

[0041] like Figure 1 As shown, in the first embodiment, an optical imaging lens of the present invention includes, from the object side to the image side, an aperture 10, a first lens 11, a second lens 12, a third lens 13, and a filter 14. Among them, the object side surface and the image side surface of the first lens 11, the second lens 12, and the third lens 13 are all aspherical surfaces.

[0042] The first lens 11 has positive refractive power, and its object side surface is convex at the near optical axis, and its image side surface is concave at the near optical axis. The second lens 12 is a second lens with positive refractive power, and its object side surface is concave at the near optical axis, and its image side surface is convex at the near optical axis. The third lens 13 is a third lens with refractive power, and its object side surface is convex at the near optical axis, and its image side surface is concave at the near optical axis.

[0043] In the above structure, the first lens 11 has positive refractive power, and its object side surface is convex at the near optical axis, and the positive refractive power configuration can be adjusted to strengthen the shortening of the total optical length; its image side surface is concave at the near optical axis, which can effectively balance low-order aberrations, facilitate light convergence, and eliminate off-axis astigmatism. The second lens 12 has positive refractive power and its object side surface is convex at the near optical axis, and the image side surface is convex at the near optical axis, which can effectively correct the paraxial spherical aberration, while reducing the peripheral astigmatism field curvature, improving the imaging quality, and balancing the high-order aberrations of the optical system. The object side surface of the third lens 13 is convex at the near optical axis, and the image side surface is concave at the near optical axis, which helps to keep the main point of the optical photography system away from the image side end, thereby effectively shortening the overall length of the optical imaging system, which is conducive to the miniaturization of the system, and can correct off-axis aberrations to improve the peripheral imaging quality. The combination of three-piece structure using plastic aspherical lenses can better correct aberrations and achieve lightweight imaging lenses.

[0044] With the above structure, reasonable material selection and refractive force matching, when specific conditions are met, the entire optics has better light focusing ability and meets high pixel requirements.

[0045] The imaging lens satisfies the relationship: ∑CT / ImgH<0.6, (SAG12+SAG21) / f<0.6; wherein ∑CT is the sum of the center thicknesses of all lenses on the optical axis, ImgH is half the diagonal length of the effective imaging area of ​​the imaging lens, SAG12 is the axial distance between the intersection of the object side of the first lens and the optical axis to the vertex of the effective radius of the object side of the first lens, SAG21 is the axial distance between the intersection of the image side of the second lens and the optical axis to the vertex of the effective radius of the image side of the second lens, and f is the focal length of the lens group. Controlling the ratio within this range can effectively control the overall length of the optical system, control the thickness of each lens, balance the size of each lens, reduce the size of the optical system, avoid excessive lens volume, and realize miniaturization of the imaging lens.

[0046] The imaging lens satisfies the relationship: 2.3<(CT1 / ET1)+(CT2 / ET2)+(CT3 / ET3)<3.6; where CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, CT3 is the center thickness of the third lens on the optical axis, ET1 is the edge thickness of the first lens, ET2 is the edge thickness of the second lens, and ET3 is the edge thickness of the third lens. By controlling the ratio of the lens optical axis focus to the effective diameter vertex axis distance and focal length, the overall shape of the lens can be controlled to achieve miniaturization of the lens. At the same time, the lens has a high space utilization rate. Under the same volume, the lens has more sufficient assembly space, which reduces the difficulty of lens assembly.

[0047] The imaging lens satisfies the relationship: (L2R1-L2R2) / f2<0.1; where L2R1 is the curvature radius of the image side of the second lens, L2R2 is the curvature radius of the object side of the second lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens. Controlling the ratio relationship is conducive to controlling the curvature radius of the second lens. A reasonable ratio relationship helps to better converge the light of the lens with positive refractive power, helps to eliminate spherical aberration, and helps to make its shape more uniform and reduce its tolerance sensitivity.

[0048] The imaging lens satisfies the relationship: f / (f3-f2)<0.5; where f is the focal length of the lens group, f2 is the focal length of the second lens, and f3 is the focal length of the third lens. Controlling the ratio can ensure that each lens group has a relatively balanced refractive power configuration, which helps to eliminate high-order aberrations and reduce the tolerance sensitivity of each lens.

[0049] The imaging lens satisfies the relationship: FNO<2.5, where FNO is the relative aperture of the lens group. A reasonable aperture value helps to ensure the imaging quality while increasing the amount of light entering the overall optical system.

[0050] The imaging lens satisfies the relationship: 0.3<BFL / ImgH<0.6; wherein BFL is the distance from the image side of the third lens to the imaging surface of the lens group on the optical axis, and ImgH is half of the diagonal length of the effective imaging area of ​​the imaging lens. Controlling the ratio helps to constrain the distance from the third lens to the imaging surface on the optical axis to be reasonable, leaving a margin for the structure and better processing space while ensuring the imaging quality.

[0051] The imaging lens satisfies the relationship: CT2 / ΣCT>0.3; wherein CT2 is the center thickness of the second lens on the optical axis, and ΣCT is the sum of the center thicknesses of all lenses on the optical axis.

[0052] The imaging lens satisfies the relationship: OTTL / f1<1; where OTTL is the distance from the front end of the first lens to the imaging surface, and f1 is the focal length of the first lens. Controlling the ratio can ensure the uniformity of the lens size and facilitate the processing and assembly of the lens.

[0053] The imaging lens satisfies the relationship: 0.45<sin 2 (Semi-FOV)<0.5; where Semi-FOV is half of the maximum field of view of the imaging lens. Controlling the ratio can control the total length of the lens while ensuring that the refractive power of the second lens is within a reasonable range, which helps to converge light and eliminate off-axis astigmatism, and improve imaging quality. Controlling the ratio is conducive to controlling the incident angle of the optical imaging lens, so that the optical imaging lens has better imaging quality, and is conducive to ensuring that the lens has a larger imaging surface while achieving miniaturization.

[0054] The imaging lens of the present invention will be described in detail through the following specific embodiments with reference to the accompanying drawings.

[0055] In the first embodiment, please combine Figure 2 and Figure 3 In the first embodiment, the imaging lens satisfies Table 1-1, Table 1-2 and Table 1-3.

[0056] Table 1-1 shows the basic parameters of the optical lens of the first embodiment:

[0057]

[0058] Table 1-2 shows the aspheric coefficients of each lens in the first embodiment:

[0059]

[0060]

[0061] Table 1-3 shows the values ​​of the conditional expressions in the first embodiment:

[0062]

[0063] In the second embodiment, please combine Figure 4 , Figure 5 and Figure 6 The present invention provides an optical imaging lens, which includes, from the object side to the image side, an aperture 20, a first lens 21, a second lens 22, a third lens 23, and a filter 24. The object side surface and the image side surface of the first lens 21, the second lens 22, and the third lens 23 are all aspherical surfaces. In the second embodiment, the imaging lens satisfies Table 2-1, Table 2-2, and Table 2-3.

[0064] Table 2-1 shows the basic parameters of the optical lens of the second embodiment:

[0065]

[0066] Table 2-2 shows the aspheric coefficients of each lens in the second embodiment:

[0067]

[0068] Table 2-3 shows the values ​​of the conditional expressions in the second embodiment:

[0069]

[0070] The third embodiment, please combine Figure 7 , Figure 8 and Fig. 9 The present invention provides an optical imaging lens, which includes, from the object side to the image side, an aperture 30, a first lens 31, a second lens 32, a third lens 33, and a filter 34. The object side surface and the image side surface of the first lens 31, the second lens 32, and the third lens 33 are all aspherical surfaces. In the third embodiment, the imaging lens satisfies Table 3-1, Table 3-2, and Table 3-3.

[0071] Table 3-1 shows the basic parameters of the optical lens of the third embodiment:

[0072]

[0073]

[0074] Table 3-2 shows the aspheric coefficients of each lens in the third embodiment:

[0075]

[0076] Table 3-3 shows the values ​​of the conditional expressions in the third embodiment:

[0077]

[0078] Fourth embodiment, please combine Fig.10 , Fig.11 and Fig.12 The present invention provides an optical imaging lens, which includes, from the object side to the image side, an aperture 40, a first lens 41, a second lens 42, a third lens 43, and a filter 44. The object side surface and the image side surface of the first lens 41, the second lens 42, and the third lens 43 are all aspherical surfaces. In the fourth embodiment, the imaging lens satisfies Table 4-1, Table 4-2, and Table 4-3.

[0079] Table 4-1 shows the basic parameters of the optical lens of the fourth embodiment:

[0080]

[0081]

[0082] Table 4-2 shows the aspheric coefficients of each lens in the fourth embodiment:

[0083]

[0084] Table 4-3 shows the values ​​of the conditional expressions in the fourth embodiment:

[0085]

[0086] The fifth embodiment, please combine Fig.13 , Fig.14 and Fig.15 The present invention provides an optical imaging lens, which includes, from the object side to the image side, an aperture 50, a first lens 51, a second lens 52, a third lens 53, and a filter 54. The object side surface and the image side surface of the first lens 51, the second lens 52, and the third lens 53 are all aspherical surfaces. In the fifth embodiment, the imaging lens satisfies Table 5-1, Table 5-2, and Table 5-3.

[0087] Table 5-1 shows the basic parameters of the optical lens of the fifth embodiment:

[0088]

[0089] Table 5-2 shows the aspheric coefficients of each lens in the fifth embodiment:

[0090]

[0091] Table 5-3 shows the values ​​of the conditional expressions in the fifth embodiment:

[0092]

[0093]

[0094] The sixth embodiment, please combine Fig.16 , Fig.17 and Fig.18 The present invention provides an optical imaging lens, which includes, from the object side to the image side, an aperture 60, a first lens 61, a second lens 62, a third lens 63, and a filter 64. The object side surface and the image side surface of the first lens 61, the second lens 62, and the third lens 63 are all aspherical surfaces. In the sixth embodiment, the imaging lens satisfies Table 6-1, Table 6-2, and Table 6-3.

[0095] Table 6-1 shows the basic parameters of the optical lens of the sixth embodiment:

[0096]

[0097] Table 6-2 shows the aspheric coefficients of each lens in the sixth embodiment:

[0098]

[0099]

[0100] Table 6-3 shows the values ​​of the conditional expressions in the sixth embodiment:

[0101]

[0102] In order to facilitate comparison of the above six embodiments, the following Table 6 summarizes the values ​​obtained by each expression under the corresponding conditions of each embodiment:

[0103]

[0104] The above optical imaging lens adopts a three-piece lens structure with a small overall volume, which is conducive to the miniaturization of the lens. By limiting the refractive force, surface shape and basic parameters of each lens, the imaging lens can maintain good optical performance while reducing the volume of the lens head and the depth of viewpoint. The optical lens has low sensitivity and good imaging quality.

[0105] Although the present invention is described in conjunction with the above specific embodiments, it is obvious that those skilled in the art can make many substitutions, modifications and changes according to the above content. Therefore, all such substitutions, improvements and changes are included in the spirit and scope of the appended claims.

Claims

1. An optical imaging lens, characterized in that: From the object side to the image side, they include: Aperture; A first lens element having positive refractive power, whose object side surface is convex at the near optical axis and whose image side surface is concave at the near optical axis; A second lens element with positive refractive power, whose object side surface is concave at the near optical axis and whose image side surface is convex at the near optical axis; A third lens element having a refractive power, whose object side surface is convex at the near optical axis and whose image side surface is concave at the near optical axis; The imaging lens satisfies the following relationship: 0.458<ΣCT / ImgH<0.551, (SAG12+SAG21) / f<0.6; Wherein, ΣCT is the sum of the center thicknesses of all lenses on the optical axis, ImgH is half the diagonal length of the effective imaging area of ​​the imaging lens, SAG12 is the on-axis distance between the intersection of the object side surface of the first lens and the optical axis to the vertex of the effective radius of the object side surface of the first lens, SAG21 is the on-axis distance between the intersection of the image side surface of the second lens and the optical axis to the vertex of the effective radius of the image side surface of the second lens, and f is the focal length of the lens group; The imaging lens satisfies the relationship: 2.848<(CT1 / ET1)+(CT2 / ET2)+(CT3 / ET3)<3.449; wherein CT1 is the center thickness of the first lens on the optical axis, CT2 is the center thickness of the second lens on the optical axis, CT3 is the center thickness of the third lens on the optical axis, ET1 is the edge thickness of the first lens, ET2 is the edge thickness of the second lens, and ET3 is the edge thickness of the third lens; The imaging lens satisfies the relationship: 0.846<OTTL / f1<0.992; wherein OTTL is the distance from the front end of the first lens to the imaging surface, and f1 is the focal length of the first lens.

2. The optical imaging lens according to claim 1, wherein: The imaging lens satisfies the relationship: |(L2R1-L2R2) / f2|<0.1; wherein L2R1 is the curvature radius of the image side surface of the second lens, L2R2 is the curvature radius of the object side surface of the second lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

3. The optical imaging lens according to claim 1, wherein: The imaging lens satisfies the relationship: f / (f3-f2)<0.5; wherein f is the focal length of the lens group, f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

4. The optical imaging lens according to claim 1, wherein: The imaging lens satisfies the relationship: FNO<2.5, where FNO is the relative aperture of the lens group.

5. The optical imaging lens according to claim 1, wherein: The imaging lens satisfies the relationship: 0.3<BFL / ImgH<0.6; wherein BFL is the distance from the image side of the third lens to the imaging surface of the lens group in the optical The distance on the axis, ImgH, is half the diagonal length of the effective imaging area of ​​the imaging lens.

6. The optical imaging lens according to claim 1, wherein: The imaging lens satisfies the relationship: CT2 / ΣCT>0.3; wherein CT2 is the center thickness of the second lens on the optical axis, and ΣCT is the sum of the center thicknesses of all lenses on the optical axis.

7. The optical imaging lens according to claim 1, wherein: The imaging lens satisfies the relationship: 0.45<sin2(Semi-FOV)<0.5; wherein Semi-FOV is half of the maximum field of view of the imaging lens.

8. The optical imaging lens according to claim 1, wherein: The object-side surfaces and image-side surfaces of the first lens, the second lens and the third lens are all aspherical surfaces.

Images