Imaging lens

Abstract

To provide an image capturing lens which satisfies a requirement of a low F-number, and yet offers good optical characteristics.SOLUTION: An image capturing lens provided herein consists of a first lens having positive refractive power, a second lens, a third lens, a fourth lens having positive refractive power, and a fifth lens having negative refractive power arranged in order from an object side to an image side, where the first lens has an object-side surface that is convex near an optical axis, the third lens has an image-side surface that is concave near the optical axis, the fourth lens has an object-side surface that is convex near the optical axis, and the fifth lens has an image-side surface that is concave near the optical axis. The image capturing lens satisfies predetermined conditional expressions.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an imaging lens that forms an image of a subject on a solid-state imaging element such as a CCD sensor or a C-MOS sensor used in an imaging device. [Background technology]

[0002] In recent years, camera functions have been installed in a variety of products, including home appliances, information terminal devices, and automobiles. It is expected that the development of various products incorporating camera functions will continue in the future.

[0003] The imaging lenses mounted on such devices are required to be compact yet have high resolution performance.

[0004] As a conventional imaging lens aiming at high performance, for example, an imaging lens as disclosed in Patent Document 1 below is known.

[0005] Patent Document 1 discloses an imaging lens which is composed of, in order from the object side, a first lens which faces a convex surface toward the object side and has a convex surface toward the image side and has positive refractive power, a second lens which faces a concave surface toward the object side and has a concave surface toward the image side and has negative refractive power, a third lens which has a flat surface toward the object side and has a convex surface toward the image side and has positive refractive power, a fourth lens which faces a concave surface toward the object side and has a concave surface toward the image side and has negative refractive power, and a fifth lens which faces a concave surface toward the object side and has a convex surface toward the image side and has negative refractive power, and which is configured so that the relationship between the distance on the optical axis from the object-side surface of the first lens to the imaging plane and the focal length of the entire imaging lens system satisfies a certain condition. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] China Patent Application Publication No. 107621684 Summary of the Invention [Problem to be solved by the invention]

[0007] If an attempt is made to reduce the F-number with the lens configuration described in Patent Document 1, it is extremely difficult to correct aberrations in the peripheral areas, and good optical performance cannot be obtained.

[0008] The present invention has been made in view of the above-mentioned problems, and has an object to provide an imaging lens that has high resolving power with various aberrations well corrected, while satisfying the demand for a low F-number in a well-balanced manner.

[0009] Regarding the terms used in the present invention, the convex, concave, and flat surfaces of a lens are defined as the shapes in the paraxial direction. The refractive power is defined as the refractive power in the paraxial direction. The pole is defined as a point on an aspheric surface other than on the optical axis where the tangent plane intersects the optical axis perpendicularly. The total optical length is defined as the distance on the optical axis from the object-side surface of the optical element located closest to the object to the imaging surface. The total optical length and back focus are the distances obtained by converting the thicknesses of an IR cut filter, a cover glass, etc., placed between the imaging lens and the imaging surface into air. [Means for solving the problem]

[0010] An imaging lens according to the present invention is composed of a first lens having positive refractive power, a second lens, a third lens, a fourth lens having positive refractive power, and a fifth lens having negative refractive power, arranged in this order from the object side to the image side, in which the first lens has a convex surface toward the object side in the paraxial direction, the third lens has a concave surface toward the image side in the paraxial direction, the fourth lens has a convex surface toward the object side in the paraxial direction, and the fifth lens has a concave surface toward the image side in the paraxial direction.

[0011] The first lens has positive refractive power and has a convex surface on the object side in the paraxial direction, thereby suppressing spherical aberration, coma, astigmatism, curvature of field, and distortion.

[0012] The second lens has aspheric surfaces on both sides, which effectively corrects coma, astigmatism, field curvature, and distortion.

[0013] The third lens has a concave surface on the image side paraxially, which provides excellent correction for coma, astigmatism, and distortion.

[0014] The fourth lens has positive refractive power and has a convex surface on the object side in the paraxial direction, thereby providing excellent correction for spherical aberration, coma, astigmatism, curvature of field, and distortion.

[0015] The fifth lens has negative refractive power and is concave on the image side at paraxial direction to effectively correct chromatic aberration, coma, astigmatism, curvature of field, and distortion. Also, by making the image side concave on paraxial direction, the back focus is secured while maintaining a low height.

[0016] In the imaging lens having the above configuration, it is preferable that the first lens has a concave surface on the image side paraxially.

[0017] By making the image-side surface of the first lens a concave surface paraxially, it becomes possible to satisfactorily correct spherical aberration, coma aberration, astigmatism, curvature of field, and distortion aberration.

[0018] By adopting the above-mentioned configuration, the imaging lens of the present invention achieves a low F-number of 4.7 or less.

[0019] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (1). (1) 26.5<|r4| / T2<100.0 Here, r4 is the paraxial radius of curvature of the image-side surface of the second lens, and T2 is the distance on the optical axis from the image-side surface of the second lens to the object-side surface of the third lens.

[0020] By satisfying the range of conditional expression (1), a low height can be achieved and coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0021] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (2). (2) 17<(D3 / |f3|)×100<60 Here, D3 is the thickness of the third lens on the optical axis, and f3 is the focal length of the third lens.

[0022] By satisfying the range of conditional expression (2), a low height can be achieved and coma, astigmatism, and distortion can be favorably corrected.

[0023] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (3). (3) -0.20 <r2 / r8<-0.02 Here, r2 is the paraxial radius of curvature of the image-side surface of the first lens, and r8 is the paraxial radius of curvature of the image-side surface of the fourth lens.

[0024] By satisfying the range of conditional expression (3), coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0025] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (4). (4)9.6 <r3 / r7×D2<25.0 Here, r3 is the paraxial radius of curvature of the object-side surface of the second lens, r7 is the paraxial radius of curvature of the object-side surface of the fourth lens, and D2 is the thickness of the second lens on the optical axis.

[0026] By satisfying the range of conditional expression (4), a low height can be achieved and coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0027] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (5). (5) 0.6 <r6 / r2<1.7 Here, r6 is the paraxial radius of curvature of the image-side surface of the third lens, and r2 is the paraxial radius of curvature of the image-side surface of the first lens.

[0028] By satisfying the range of conditional expression (5), coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0029] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (6). (6)-50 <r8 / f<-3 Here, r8 is the paraxial radius of curvature of the image-side surface of the fourth lens, and f is the focal length of the entire imaging lens system.

[0030] By satisfying the range of conditional expression (6), coma, astigmatism, and distortion can be corrected satisfactorily.

[0031] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (7). (7)-10.75 <r10 / (D5-T4)<-0.50 where r10 is the paraxial radius of curvature of the image-side surface of the fifth lens, D5 is the thickness of the fifth lens on the optical axis, and T4 is the distance on the optical axis from the image-side surface of the fourth lens to the object-side surface of the fifth lens.

[0032] By satisfying the range of conditional expression (7), a low height can be achieved and coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0033] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (8). (8)11<νd4<27 Here, νd4 is the Abbe number for the d-line of the fourth lens.

[0034] By satisfying the range of conditional expression (8), chromatic aberration can be corrected satisfactorily.

[0035] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (9). (9) 11<νd5<36 Here, νd5 is the Abbe number for the d-line of the fifth lens.

[0036] By satisfying the range of conditional expression (9), chromatic aberration can be corrected satisfactorily.

[0037] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (10). (10)0.03 <r2 / r3<0.20 Here, r2 is the paraxial radius of curvature of the image-side surface of the first lens, and r3 is the paraxial radius of curvature of the object-side surface of the second lens.

[0038] By satisfying the range of conditional expression (10), coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0039] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (11). (11) 0.25<(r2 / r3 / r7)×100<1.45 Here, r2 is the paraxial radius of curvature of the image-side surface of the first lens, r3 is the paraxial radius of curvature of the object-side surface of the second lens, and r7 is the paraxial radius of curvature of the object-side surface of the fourth lens.

[0040] By satisfying the range of conditional expression (11), coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0041] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (12). (12)-0.05 <r2 / |r5| / r8<0.00 Here, r2 is the paraxial radius of curvature of the image-side surface of the first lens, r5 is the paraxial radius of curvature of the object-side surface of the third lens, and r8 is the paraxial radius of curvature of the image-side surface of the fourth lens.

[0042] By satisfying the range of conditional expression (12), coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0043] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (13). (13)0.10<(r2 / r3 / |r9|)×100<0.40 Here, r2 is the paraxial radius of curvature of the image-side surface of the first lens, r3 is the paraxial radius of curvature of the object-side surface of the second lens, and r9 is the paraxial radius of curvature of the object-side surface of the fifth lens.

[0044] By satisfying the range of conditional expression (13), coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0045] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (14). (14)2.5 <r3 / f<10.0 Here, r3 is the paraxial radius of curvature of the object side surface of the second lens, and f is the focal length of the entire imaging lens system.

[0046] By satisfying the range of conditional expression (14), coma, astigmatism, and distortion can be corrected satisfactorily.

[0047] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (15). (15)8 <r3 / |r4|<41 Here, r3 is the paraxial radius of curvature of the object-side surface of the second lens, and r4 is the paraxial radius of curvature of the image-side surface of the second lens.

[0048] By satisfying the range of conditional expression (15), coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0049] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (16). (16) 0.1<|r5| / f<0.4 Here, r5 is the paraxial radius of curvature of the object side surface of the third lens, and f is the focal length of the entire imaging lens system.

[0050] By satisfying the range of conditional expression (16), coma, astigmatism, and distortion can be corrected satisfactorily.

[0051] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (17). (17) 0.01<|r5| / r3<0.10 Here, r5 is the paraxial radius of curvature of the object-side surface of the third lens, and r3 is the paraxial radius of curvature of the object-side surface of the second lens.

[0052] By satisfying the range of conditional expression (17), coma, astigmatism, and distortion can be corrected satisfactorily.

[0053] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (18). (18)0.3 <r7 / T4<4.5 Here, r7 is the paraxial radius of curvature of the object-side surface of the fourth lens, and T4 is the distance on the optical axis from the image-side surface of the fourth lens to the object-side surface of the fifth lens.

[0054] By satisfying the range of conditional expression (18), a low height can be achieved and good correction of astigmatism, curvature of field, and distortion can be achieved.

[0055] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (19). (19)-0.08 <r7 / r8<-0.02 Here, r7 is the paraxial radius of curvature of the object-side surface of the fourth lens, and r8 is the paraxial radius of curvature of the image-side surface of the fourth lens.

[0056] By satisfying the range of conditional expression (19), coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0057] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (20). (20)-22.5 <r8 / f4<-4.0 Here, r8 is the paraxial radius of curvature of the image-side surface of the fourth lens, and f4 is the focal length of the fourth lens.

[0058] By satisfying the range of conditional expression (20), a low height can be achieved and spherical aberration, coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0059] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (21). (21)-20.0 <r8 / |r9|<-2.2 Here, r8 is the paraxial radius of curvature of the image-side surface of the fourth lens, and r9 is the paraxial radius of curvature of the object-side surface of the fifth lens.

[0060] By satisfying the range of conditional expression (21), coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0061] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (22). (22) 1.50<|r9| / T4<15.75 Here, r9 is the paraxial radius of curvature of the object-side surface of the fifth lens, and T4 is the distance on the optical axis from the image-side surface of the fourth lens to the object-side surface of the fifth lens.

[0062] By satisfying the range of conditional expression (22), a low height can be achieved and coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0063] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (23). (23) 1.5<|r9| / r10<6.5 Here, r9 is the paraxial radius of curvature of the object-side surface of the fifth lens, and r10 is the paraxial radius of curvature of the image-side surface of the fifth lens.

[0064] By satisfying the range of conditional expression (23), coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0065] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (24). (24)0.02 <r10 / r3<0.20 Here, r10 is the paraxial radius of curvature of the image-side surface of the fifth lens, and r3 is the paraxial radius of curvature of the object-side surface of the second lens.

[0066] By satisfying the range of conditional expression (24), coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0067] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (25). (25) 3<(D1 / f1)×100<11 Here, D1 is the thickness of the first lens on the optical axis, and f1 is the focal length of the first lens.

[0068] By satisfying the range of conditional expression (25), a low height can be achieved and spherical aberration, coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0069] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (26). (26) 9<(D4 / f4)×100<30 Here, D4 ​​is the thickness of the fourth lens on the optical axis, and f4 is the focal length of the fourth lens.

[0070] By satisfying the range of conditional expression (26), a low height can be achieved and spherical aberration, coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0071] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (27): (27)45<|f2| / T2<160 Here, f2 is the focal length of the second lens, and T2 is the distance on the optical axis from the image-side surface of the second lens to the object-side surface of the third lens.

[0072] By satisfying the range of conditional expression (27), a low height can be achieved and coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0073] According to the present invention, it is possible to obtain an imaging lens having high resolution and in which various aberrations are well corrected while satisfying the demand for a low F-number in a well-balanced manner. [Brief description of the drawings]

[0074] [Figure 1] 1 is a diagram showing a schematic configuration of an imaging lens according to a first embodiment of the present invention. [Diagram 2] 4A to 4C are diagrams illustrating spherical aberration, astigmatism, and distortion of the imaging lens according to the first embodiment of the present invention. [Diagram 3] FIG. 11 is a diagram showing a schematic configuration of an imaging lens according to a second embodiment of the present invention. [Figure 4] 5A to 5C are diagrams illustrating spherical aberration, astigmatism, and distortion of the imaging lens according to Example 2 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0075] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0076] 1 and 3 are schematic configuration diagrams of imaging lenses according to Examples 1 and 2 of the embodiments of the present invention, respectively. Details of the embodiments of the present invention will be described below with reference to FIG.

[0077] As shown in FIG. 1, the imaging lens according to the present invention is composed of a first lens L1 having positive refractive power, a second lens L2, a third lens L3, a fourth lens L4 having positive refractive power, and a fifth lens L5 having negative refractive power, arranged in this order from the object side to the image side, in which the first lens L1 has a convex surface on the object side in the paraxial direction, the third lens L3 has a concave surface on the image side in the paraxial direction, the fourth lens L4 has a convex surface on the object side in the paraxial direction, and the fifth lens L5 has a concave surface on the image side in the paraxial direction.

[0078] In addition, a filter IR such as an infrared cut filter or a cover glass is disposed between the fifth lens L5 and the imaging surface IMG (that is, the imaging surface of the imaging element). Note that this filter IR can be omitted.

[0079] The aperture stop ST is disposed on the object side of the first lens L1, which facilitates correction of various aberrations and facilitates control of the angle at which light rays with high image heights enter the image sensor. The position of the aperture stop ST is not limited to between the first lens L1 and the second lens L2. It may be disposed as appropriate according to the specifications of the image sensor.

[0080] The first lens L1 has positive refractive power and is a meniscus shape with a convex surface on the object side paraxially, thereby suppressing spherical aberration, coma, astigmatism, curvature of field, and distortion.

[0081] The second lens L2 has positive refractive power and is biconvex on the paraxial direction, thereby providing excellent correction for coma, astigmatism, curvature of field, and distortion.

[0082] The refractive power of the second lens L2 may be negative, as in Example 2 shown in Fig. 3. In this case, it is advantageous for correcting chromatic aberration.

[0083] The shape of the second lens L2 may be a meniscus shape with a convex surface on the object side paraxially, as in Example 2 shown in Fig. 3. In this case, it is advantageous for correcting astigmatism, curvature of field, and distortion.

[0084] The third lens L3 has negative refractive power and is biconcave on the paraxial direction, thereby effectively correcting coma, astigmatism, and distortion.

[0085] The refractive power of the third lens L3 may be positive as in Example 2 shown in Fig. 3. In this case, it is advantageous for reducing the height.

[0086] The shape of the third lens L3 may be a meniscus shape with a concave surface on the image side paraxially, as in Example 2 shown in Fig. 3. In this case, it is advantageous for correcting coma, astigmatism, and distortion.

[0087] The fourth lens L4 has a positive refractive power and is a biconvex shape on the paraxial line. Therefore, spherical aberration, coma aberration, astigmatism, field curvature, and distortion aberration are well corrected. The shape of the fourth lens L4 is not limited to the shape according to the first numerical example. The shape of the fourth lens L4 may be a meniscus shape with a convex surface on the object side on the paraxial line.

[0088] The fifth lens L5 has negative refractive power and is a meniscus shape with a concave surface on the image side at paraxial position. Therefore, chromatic aberration, coma aberration, astigmatism, curvature of field, and distortion aberration are corrected well. In addition, by making the image side concave at paraxial position, the back focus is secured while maintaining a low height.

[0089] The shape of the fifth lens L5 may be a paraxial biconcave shape as in Example 2 shown in Fig. 3. In this case, the negative refractive power on both sides is advantageous for correcting chromatic aberration.

[0090] In the imaging lens according to this embodiment, it is preferable that each of the first lens L1 to the fifth lens L5 is composed of a single lens. A composition consisting of only single lenses can make extensive use of aspherical surfaces. In this embodiment, by forming appropriate aspherical surfaces on all lens surfaces, various aberrations are corrected satisfactorily. In addition, since the number of steps can be reduced compared to the case of using cemented lenses, it is possible to manufacture the lens at low cost.

[0091] Moreover, in the imaging lens according to this embodiment, it is desirable to form all lens surfaces aspheric surfaces, but depending on the required performance, spherical surfaces, which are easier to manufacture, may be used.

[0092] The imaging lens of this embodiment exerts favorable effects by satisfying the following conditional expressions (1) to (27). (1) 26.5<|r4| / T2<100.0 (2) 17<(D3 / |f3|)×100<60 (3) -0.20 <r2 / r8<-0.02 (4)9.6 <r3 / r7×D2<25.0 (5) 0.6 <r6 / r2<1.7 (6)-50 <r8 / f<-3 (7)-10.75 <r10 / (D5-T4)<-0.50 (8)11<νd4<27 (9) 11<νd5<36 (10)0.03 <r2 / r3<0.20 (11) 0.25<(r2 / r3 / r7)×100<1.45 (12)-0.05 <r2 / |r5| / r8<0.00 (13)0.10<(r2 / r3 / |r9|)×100<0.40 (14)2.5 <r3 / f<10.0 (15)8 <r3 / |r4|<41 (16) 0.1<|r5| / f<0.4 (17) 0.01<|r5| / r3<0.10 (18)0.3 <r7 / T4<4.5 (19)-0.08 <r7 / r8<-0.02 (20)-22.5 <r8 / f4<-4.0 (21)-20.0 <r8 / |r9|<-2.2 (22) 1.50<|r9| / T4<15.75 (23) 1.5<|r9| / r10<6.5 (24)0.02 <r10 / r3<0.20 (25) 3<(D1 / f1)×100<11 (26) 9<(D4 / f4)×100<30 (27) 45<|f2| / T2<160, where however, νd4: Abbe number for the d line of the fourth lens L4 νd5: Abbe number for the d line of the fifth lens L5 D1: Thickness of the first lens L1 on the optical axis X D2: Thickness of the second lens L2 on the optical axis X D3: Thickness of the third lens L3 on the optical axis X D5: Thickness of the fifth lens L5 on the optical axis X T2: the distance on the optical axis X from the image-side surface of the second lens L2 to the object-side surface of the third lens L3 T4: the distance on the optical axis X from the image-side surface of the fourth lens L4 to the object-side surface of the fifth lens L5 f: focal length of the entire imaging lens system f1: focal length of the first lens L1 f2: focal length of second lens L2 f3: focal length of the third lens L3 f4: focal length of the fourth lens L4 r2: paraxial radius of curvature of the image-side surface of the first lens L1 r3: paraxial radius of curvature of the object side surface of the second lens L2 r4: paraxial radius of curvature of the image-side surface of the second lens L2 r5: paraxial radius of curvature of the object-side surface of the third lens L3 r6: Paraxial curvature radius of the image side surface of the third lens L3 r7: Paraxial radius of curvature of the object side surface of the fourth lens L4 r8: Paraxial curvature radius of the image side surface of the fourth lens L4 r9: paraxial radius of curvature of the object side surface of the fifth lens L5 r10: Paraxial curvature radius of the image side surface of the fifth lens L5 It is not necessary to satisfy all of the above conditional expressions. By satisfying each conditional expression individually, it is possible to obtain the effect corresponding to each conditional expression.

[0093] Moreover, the imaging lens of this embodiment exerts more preferable effects by satisfying the following conditional expressions (1a) to (27a). (1a) 39.5<|r4| / T2<80.0 (2a) 23<(D3 / |f3|)×100<44 (3a)-0.13 <r2 / r8<-0.03 (4a)11 <r3 / r7×D2<20 (5a) 0.8 <r6 / r2<1.4 (6a)-32.5 <r8 / f<-6.5 (7a)-9.5 <r10 / (D5-T4)<-0.9 (8a)15<νd4<23 (9a)15<νd5<31 (10a) 0.06 <r2 / r3<0.15 (11a) 0.6<(r2 / r3 / r7)×100<1.2 (12a)-0.03 <r2 / |r5| / r8<0.00 (13a)0.18<(r2 / r3 / |r9|)×100<0.30 (14a)3.2 <r3 / f<8.0 (15a)12 <r3 / |r4|<34 (16a) 0.15<|r5| / f<0.30 (17a) 0.02<|r5| / r3<0.08 (18a) 0.6 <r7 / T4<3.5 (19a)-0.06 <r7 / r8<-0.03 (20a)-20 <r8 / f4<-11 (21a)-13 <r8 / |r9|<-4 (22a) 2.50<|r9| / T4<13.50 (23a) 2.5<|r9| / r10<5.5 (24a) 0.05 <r10 / r3<0.15 (25a) 4.5<(D1 / f1)×100<8.5 (26a) 14<(D4 / f4)×100<25 (27a) 65<|f2| / T2<130 However, the symbols in each conditional expression are the same as those explained in the previous paragraph. Note that only the lower limit value or only the upper limit value of each of the conditional expressions (1a) to (27a) may be applied to the corresponding conditional expressions (1) to (27).

[0094] In this embodiment, the aspheric shape adopted for the aspheric surface of the lens surface is expressed by Formula 1, where Z is the axis in the optical axis direction, H is the height in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, k is the conic coefficient, and A4, A6, A8, A10, A12, A14, and A16 are aspheric coefficients.

[0095]

number

[0096] Next, examples of the imaging lens according to this embodiment are shown. In each example, f denotes the focal length of the entire imaging lens system, Fno denotes the F-number, ω denotes the half angle of view, ih denotes the maximum image height, and TTL denotes the total optical length. Also, i denotes the surface number counted from the object side, r denotes the paraxial radius of curvature, d denotes the distance between lens surfaces on the optical axis (surface spacing), Nd denotes the refractive index of the d-line (reference wavelength), and νd denotes the Abbe number for the d-line. Aspheric surfaces are indicated by adding an asterisk (*) after the surface number i.

[0097] Example 1

[0098] Basic lens data is shown in Table 1 below.

[0099] [Table 1]

[0100] The imaging lens of Example 1 achieves an F-number of 4.5, and satisfies conditional expressions (1) to (27) as shown in Table 3.

[0101] Fig. 2 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens of Example 1. The spherical aberration diagram shows the amount of aberration for each wavelength of the F-line (486 nm), d-line (588 nm), and C-line (656 nm). The astigmatism diagram also shows the amount of aberration for the d-line at the sagittal image plane S (solid line) and the amount of aberration for the d-line at the tangential image plane T (dashed line) (the same applies to Fig. 4). As shown in Fig. 2, it can be seen that each aberration is well corrected.

[0102] Example 2

[0103] Basic lens data is shown in Table 2 below.

[0104] [Table 2]

[0105] The imaging lens of Example 2 achieves an F-number of 4.5 and satisfies conditional expressions (1) to (27) as shown in Table 3.

[0106] Fig. 4 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 2. As shown in Fig. 4, it can be seen that each aberration is well corrected.

[0107] Table 3 shows values ​​of conditional expressions (1) to (27) according to the first and second embodiments.

[0108] [Table 3] [Industrial Applicability]

[0109] When the imaging lens according to the present invention is applied to a product equipped with a camera function, it contributes to a lower F-number of the camera and also improves the performance. [Explanation of symbols]

[0110] ST aperture stop L1 First lens L2 Second lens L3 Third lens L4 4th lens L5 5th lens IR Filter IMG Imaging surface

Claims

1. Arranged in order from the object side to the image side, a first lens having a positive refractive power; A second lens; A third lens; a fourth lens having a positive refractive power; a fifth lens having a negative refractive power; the first lens has a convex surface on the object side in a paraxial direction; the third lens has a paraxial concave surface on the image side, the fourth lens has a paraxial convex surface facing the object side, the fifth lens has a paraxial concave surface on the image side, An imaging lens characterized by satisfying the following conditional expressions (1) and (2): (1) 26.5<|r4| / T2<100.0 (2) 17<(D3 / |f3|)×100<60 however, r4: paraxial radius of curvature of the image side surface of the second lens T2: the distance on the optical axis from the image side surface of the second lens to the object side surface of the third lens D3: Thickness of the third lens on the optical axis f3: focal length of the third lens

2. 2. The imaging lens according to claim 1, wherein the first lens has a concave surface on the image side in a paraxial direction.

3. 2. The imaging lens according to claim 1, wherein the following conditional expression (3) is satisfied: (3) -0.20<r2 / r8<-0.02 however, r2: paraxial radius of curvature of the image side surface of the first lens r8: paraxial radius of curvature of the image side surface of the fourth lens

4. 2. The imaging lens according to claim 1, wherein the following conditional expression (4) is satisfied: (4) 9.6<r3 / r7×D2<25.0 however, r3: paraxial radius of curvature of the object side surface of the second lens r7: paraxial radius of curvature of the object side surface of the fourth lens D2: Thickness of the second lens on the optical axis

5. 2. The imaging lens according to claim 1, wherein the following conditional expression (5) is satisfied: (5) 0.6<r6 / r2<1.7 however, r6: paraxial radius of curvature of the image side surface of the third lens r2: paraxial radius of curvature of the image side surface of the first lens

6. 2. The imaging lens according to claim 1, wherein the following conditional expression (6) is satisfied: (6) -50<r8 / f<-3 however, r8: paraxial radius of curvature of the image side surface of the fourth lens f: focal length of the entire imaging lens system

7. 2. The imaging lens according to claim 1, wherein the following conditional expression (7) is satisfied: (7) -10.75<r10 / (D5-T4)<-0.50 however, r10: paraxial radius of curvature of the image side surface of the fifth lens D5: Thickness of the fifth lens on the optical axis T4: The distance on the optical axis from the image side surface of the fourth lens to the object side surface of the fifth lens

Images