Imaging lens

Abstract

To provide an imaging lens having an excellent optical characteristic, while satisfying requirements for a height reduction and a small F number.SOLUTION: The imaging lens comprises a first lens having negative refractive power, a second lens having positive refractive power, a third lens having negative refractive power, 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. The first lens has a concave surface on the image side on a paraxial axis and the fifth lens has a concave surface on the image side on the paraxial axis. The imaging lens satisfies a predetermined conditional expression.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 having negative refractive power, a second lens having positive refractive power, a third lens having negative refractive power, a fourth lens having positive refractive power, and a fifth lens having negative refractive power, in which the relationship between the focal length of the third lens and the focal length of the entire imaging lens system, the relationship between the paraxial radius of curvature of the object-side surface of the second lens and the optical axial thickness of the second lens, the relationship between the paraxial radius of curvature of the object-side surface of the third lens and the paraxial radius of curvature of the image-side surface of the third lens, the optical axial thickness of the first lens, and the optical axial distance from the image-side surface of the first lens to the object-side surface of the second lens satisfy certain conditions. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] China Patent Application Publication No. 110850562 Summary of the Invention [Problem to be solved by the invention]

[0007] When attempting to reduce the height and 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 in a well-balanced manner the requirements for a low height and a low F-number.

[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, arranged in order from the object side to the image side, a first lens having negative refractive power, a second lens having positive refractive power, a third lens having negative refractive power, a fourth lens having positive refractive power, and a fifth lens having negative refractive power, wherein the first lens has a concave surface on the image side paraxially, and the fifth lens has a concave surface on the image side paraxially.

[0011] The first lens has negative refractive power and has a concave surface on the image side paraxially, thereby suppressing chromatic aberration, coma, astigmatism, and distortion.

[0012] The second lens has a positive refractive power, thereby achieving a low height and effectively correcting spherical aberration, astigmatism, curvature of field, and distortion.

[0013] The third lens has a negative refractive power, and thereby effectively corrects chromatic aberration, coma aberration, astigmatism, curvature of field, and distortion.

[0014] The fourth lens has a positive refractive power, thereby achieving a low height and effectively correcting 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 position to effectively correct chromatic aberration, astigmatism, curvature of field, and distortion. Also, by making the image side concave at paraxial position, the back focus is secured while maintaining a low height.

[0016] In the imaging lens having the above configuration, it is preferable that the second lens has a convex surface on the object side in the paraxial direction.

[0017] By making the object-side surface of the second lens a convex surface in the paraxial direction, it becomes possible to satisfactorily correct astigmatism, curvature of field, and distortion.

[0018] In the imaging lens having the above configuration, it is preferable that the third lens has a convex surface on the object side in the paraxial direction.

[0019] By making the object-side surface of the third lens a convex surface on the paraxial direction, coma, astigmatism, curvature of field, and distortion can be effectively corrected.

[0020] In the imaging lens having the above configuration, it is preferable that the fourth lens has a concave surface on the object side paraxially.

[0021] By making the object-side surface of the fourth lens a concave surface paraxially, coma, astigmatism, curvature of field, and distortion can be effectively corrected.

[0022] In the imaging lens having the above configuration, it is preferable that the fifth lens has a convex surface on the object side paraxially.

[0023] By making the object-side surface of the fifth lens a convex surface on the paraxial direction, it becomes possible to satisfactorily correct astigmatism, curvature of field, and distortion.

[0024] In the imaging lens having the above configuration, it is preferable that the object-side surface of the fifth lens is formed as an aspheric surface having a pole at a position other than on the optical axis.

[0025] By forming an aspheric surface having a pole point at a position other than on the optical axis on the object side surface of the fifth lens, it becomes possible to more effectively correct astigmatism, curvature of field, and distortion.

[0026] In the imaging lens having the above configuration, it is preferable that the image-side surface of the fifth lens is formed as an aspheric surface having a pole at a position other than on the optical axis.

[0027] By forming an aspheric surface having a pole point at a position other than on the optical axis on the image-side surface of the fifth lens, it becomes possible to more effectively correct astigmatism, curvature of field, and distortion.

[0028] By adopting the above-mentioned configuration, the imaging lens of the present invention achieves a low height with a total-to-diagonal ratio (the ratio of the total optical length to the diagonal length of the effective imaging surface of the image sensor) of 0.95 or less, and a low F-number of 2.5 or less.

[0029] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (1). (1)-400 mm <r1×r2 / f1<-1 mm Here, r1 is the paraxial radius of curvature of the object-side surface of the first lens, r2 is the paraxial radius of curvature of the image-side surface of the first lens, and f1 is the focal length of the first lens.

[0030] By satisfying the range of conditional expression (1), chromatic aberration, coma, astigmatism, and distortion can be favorably corrected.

[0031] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (2). (2)-2.00 mm -1 <r3 / r7 / D2<-0.55 mm -1 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.

[0032] By satisfying the range of conditional expression (2), 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 (3). (3)20 <r5 / T2<120 Here, r5 is the paraxial radius of curvature of the object-side surface of the third 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.

[0034] By satisfying the range of conditional expression (3), a low height can be achieved and coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0035] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (4). (4) -1.50 <r9 / f5<-0.65 Here, r9 is the paraxial radius of curvature of the object side surface of the fifth lens, and f5 is the focal length of the fifth lens.

[0036] By satisfying the range of conditional expression (4), chromatic aberration, astigmatism, curvature of field, and distortion can be favorably corrected.

[0037] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (5). (5) 15<νd5<36 Here, νd5 is the Abbe number for the d-line of the fifth lens.

[0038] By satisfying the range of conditional expression (5), chromatic aberration can be corrected satisfactorily.

[0039] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (6). (6)-65.0 <r4 / T2<-7.3 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.

[0040] By satisfying the range of conditional expression (6), a low height can be achieved and spherical aberration, astigmatism, curvature of field, and distortion can be favorably corrected.

[0041] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (7). (7)-875 <r7 / (T3-T2)<-10 where r7 is the paraxial radius of curvature of the object-side surface of the fourth lens, T3 is the distance on the optical axis from the image-side surface of the third lens to the object-side surface of the fourth 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.

[0042] 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.

[0043] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (8). (8)-20.5 mm -1 <(r2 / r3 / r7)×100<-6.5 mm -1 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.

[0044] By satisfying the range of conditional expression (8), coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0045] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (9). (9)-40 <r8 / T4<-7 Here, r8 is the paraxial radius of curvature of the image-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.

[0046] By satisfying the range of conditional expression (9), a low height can be achieved and coma, astigmatism, curvature of field, and distortion can be favorably corrected.

[0047] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (10). (10)-10.5<(D1 / f1)×100<-5.0 Here, D1 is the thickness of the first lens on the optical axis, and f1 is the focal length of the first lens.

[0048] By satisfying the range of conditional expression (10), a low height can be achieved and chromatic aberration, coma, astigmatism, and distortion can be favorably corrected.

[0049] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (11). (11)-6.0 <f5 / D5<-1.5 Here, f5 is the focal length of the fifth lens, and D5 is the thickness of the fifth lens on the optical axis.

[0050] By satisfying the range of conditional expression (11), a low height can be achieved and chromatic aberration, astigmatism, curvature of field, and distortion can be favorably corrected.

[0051] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (12). (12)3.5 <r1 / f<400.0 Here, r1 is the paraxial radius of curvature of the object side surface of the first lens, and f is the focal length of the entire imaging lens system.

[0052] By satisfying the range of conditional expression (12), 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 (13). (13)2.2 <r2 / T1<13.0 Here, r2 is the paraxial radius of curvature of the image-side surface of the first lens, and T1 is the distance on the optical axis from the image-side surface of the first lens to the object-side surface of the second lens.

[0054] By satisfying the range of conditional expression (13), a low height can be achieved and coma, astigmatism, and distortion can be favorably corrected.

[0055] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (14). (14)0.4 mm -1 <(r5 / r6 / r1)×100<40.0 mm -1 Here, r5 is the paraxial radius of curvature of the object side surface of the third lens, r6 is the paraxial radius of curvature of the image side surface of the third lens, and r1 is the paraxial radius of curvature of the object side surface of the first lens.

[0056] By satisfying the range of conditional expression (14), 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 (15). (15) 0.3<(r2 / r1)×100<30.0 Here, r2 is the paraxial radius of curvature of the image-side surface of the first lens, and r1 is the paraxial radius of curvature of the object-side surface of the first lens.

[0058] By satisfying the range of conditional expression (15), coma, astigmatism, and distortion can be corrected satisfactorily.

[0059] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (16). (16)-1.40 mm -1 <r2 / r5 / r8<-0.25 mm -1 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.

[0060] By satisfying the range of conditional expression (16), 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 (17). (17)1.0 <r5 / r2<5.5 Here, r5 is the paraxial radius of curvature of the object side surface of the third lens, and r2 is the paraxial radius of curvature of the image side surface of the first lens.

[0062] By satisfying the range of conditional expression (17), coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0063] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (18). (18)0.45 <r6 / r2<1.90 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.

[0064] By satisfying the range of conditional expression (18), coma, astigmatism, 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 (19). (19)0.7 <f3 / f1<2.2 Here, f3 is the focal length of the third lens, and f1 is the focal length of the first lens.

[0066] By satisfying the range of conditional expression (19), chromatic aberration, 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 (20). (20)0.30 <f4 / f<0.85 Here, f4 is the focal length of the fourth lens, and f is the focal length of the entire imaging lens system.

[0068] By satisfying the range of conditional expression (20), it becomes possible to satisfactorily correct spherical aberration, coma, astigmatism, curvature of field, and distortion.

[0069] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (21). (21)-1.1 <f5 / f<-0.2 Here, f5 is the focal length of the fifth lens, and f is the focal length of the entire imaging lens system.

[0070] By satisfying the range of conditional expression (21), chromatic aberration, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0071] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (22). (22)-1.25 <f4 / f5<-0.70 Here, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens.

[0072] By satisfying the range of conditional expression (22), chromatic aberration, spherical aberration, coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0073] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (23). (23)-1.8 <f2 / f5<-0.9 Here, f2 is the focal length of the second lens, and f5 is the focal length of the fifth lens.

[0074] By satisfying the range of conditional expression (23), chromatic aberration, spherical aberration, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0075] Moreover, in the imaging lens having the above configuration, it is desirable to satisfy the following conditional expression (24). (24)-0.40<(f4 / f)+(f5 / f)<-0.05 Here, f4 is the focal length of the fourth lens, f5 is the focal length of the fifth lens, and f is the focal length of the entire imaging lens system.

[0076] By satisfying the range of conditional expression (24), chromatic aberration, spherical aberration, coma, astigmatism, curvature of field, and distortion can be corrected satisfactorily.

[0077] 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 requirements for a low height and a low F-number in a well-balanced manner. [Brief description of the drawings]

[0078] [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] 3A to 3C 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. [Diagram 5] FIG. 11 is a diagram showing a schematic configuration of an imaging lens according to a third embodiment of the present invention. [Figure 6] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion of the imaging lens according to Example 3 of the present invention. [Figure 7] FIG. 11 is a diagram showing a schematic configuration of an imaging lens according to a fourth embodiment of the present invention. [Figure 8] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion of the imaging lens according to Example 4 of the present invention. [Figure 9] FIG. 11 is a diagram showing a schematic configuration of an imaging lens according to a fifth embodiment of the present invention. [Figure 10] 13A to 13C are diagrams illustrating spherical aberration, astigmatism, and distortion of the imaging lens according to Example 5 of the present invention. [Figure 11] FIG. 13 is a diagram showing a schematic configuration of an imaging lens according to a sixth embodiment of the present invention. [Figure 12] 13 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to Example 6 of the present invention. [Figure 13] FIG. 13 is a diagram showing a schematic configuration of an imaging lens according to a seventh embodiment of the present invention. [Figure 14] 13 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to Example 7 of the present invention. FIG. [Figure 15] FIG. 13 is a diagram showing a schematic configuration of an imaging lens according to an eighth embodiment of the present invention. [Figure 16] 13 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to Example 8 of the present invention. FIG. [Figure 17] FIG. 13 is a diagram showing a schematic configuration of an imaging lens according to a ninth embodiment of the present invention. [Figure 18] 13 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to Example 9 of the present invention. FIG. [Figure 19] FIG. 15 is a diagram showing a schematic configuration of an imaging lens according to a tenth embodiment of the present invention. [Figure 20] 13A to 13C are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens according to Example 10 of the present invention. [Figure 21] FIG. 23 is a diagram showing a schematic configuration of an imaging lens according to an eleventh embodiment of the present invention. [Figure 22] 13 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to Example 11 of the present invention. FIG. [Figure 23] FIG. 23 is a diagram showing a schematic configuration of an imaging lens according to a twelfth embodiment of the present invention. [Figure 24] 13A to 13C are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens according to Example 12 of the present invention. [Diagram 25] FIG. 23 is a diagram showing a schematic configuration of an imaging lens according to a thirteenth embodiment of the present invention. [Figure 26] 13A to 13C are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens according to Example 13 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0079] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0080] Figures 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, and 25 respectively show schematic configuration diagrams of imaging lenses according to Examples 1 to 13 of embodiments of the present invention. Details of the embodiments of the present invention will be described below with reference to Figure 1.

[0081] As shown in FIG. 1, an imaging lens according to the present invention is composed of, arranged in order from the object side to the image side, a first lens L1 having negative refractive power, a second lens L2 having positive refractive power, a third lens L3 having negative refractive power, a fourth lens L4 having positive refractive power, and a fifth lens L5 having negative refractive power, wherein the first lens L1 has a concave surface on the image side in a paraxial direction, and the fifth lens L5 has a concave surface on the image side in a paraxial direction.

[0082] 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.

[0083] The aperture stop ST is disposed between the first lens L1 and the second lens L2, which facilitates correction of distortion. 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 appropriately according to the specifications of the image sensor.

[0084] The first lens L1 has negative refractive power and is a meniscus shape with a concave surface on the image side paraxially, thereby suppressing chromatic aberration, coma, astigmatism, and distortion.

[0085] The second lens L2 has positive refractive power and is biconvex on the paraxial direction, which allows for a low height and excellent correction of spherical aberration, astigmatism, curvature of field, and distortion.

[0086] The third lens L3 has a negative refractive power and is a meniscus shape with a convex surface on the object side in the paraxial direction. Therefore, chromatic aberration, coma aberration, astigmatism, field curvature, and distortion aberration are well corrected. The shape of the third lens L3 is not limited to the shape according to the present Numerical Example 1. The shape of the third lens L3 may be a reverse meniscus shape, that is, a meniscus shape with a concave surface on the object side in the paraxial direction.

[0087] The fourth lens L4 has positive refractive power and a meniscus shape with a concave surface on the object side paraxially, which allows for a low height and excellent correction of spherical aberration, coma, astigmatism, curvature of field, and distortion.

[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, 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] In addition, the aspheric surface formed on the object side surface of the fifth lens L5 has a pole point at a position other than on the optical axis X. Therefore, astigmatism, curvature of field, and distortion are corrected more satisfactorily.

[0090] Furthermore, the aspheric surface formed on the image-side surface of the fifth lens L5 has a pole point at a position other than on the optical axis X. Therefore, astigmatism, field curvature, and distortion are corrected more satisfactorily.

[0091] 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.

[0092] Furthermore, the imaging lens according to this embodiment is easy to manufacture by using plastic materials for all the lenses, enabling mass production at low cost.

[0093] The lens material is not limited to plastic materials. It is possible to aim for even higher performance by using glass materials. It is also preferable to form all lens surfaces aspheric, but depending on the required performance, spherical surfaces, which are easier to manufacture, may be used.

[0094] The imaging lens of this embodiment exerts favorable effects by satisfying the following conditional expressions (1) to (24). (1)-400 mm <r1×r2 / f1<-1 mm (2)-2.00 mm -1 <r3 / r7 / D2<-0.55 mm -1 (3)20 <r5 / T2<120 (4) -1.50 <r9 / f5<-0.65 (5) 15<νd5<36 (6)-65.0 <r4 / T2<-7.3 (7)-875 <r7 / (T3-T2)<-10 (8)-20.5 mm -1 <(r2 / r3 / r7)×100<-6.5 mm -1 (9)-40 <r8 / T4<-7 (10)-10.5<(D1 / f1)×100<-5.0 (11)-6.0 <f5 / D5<-1.5 (12)3.5 <r1 / f<400.0 (13)2.2 <r2 / T1<13.0 (14)0.4 mm -1 <(r5 / r6 / r1)×100<40.0 mm -1 (15) 0.3<(r2 / r1)×100<30.0 (16)-1.40 mm -1 <r2 / r5 / r8<-0.25 mm -1 (17)1.0 <r5 / r2<5.5 (18)0.45 <r6 / r2<1.90 (19)0.7 <f3 / f1<2.2 (20)0.30 <f4 / f<0.85 (21)-1.1 <f5 / f<-0.2 (22)-1.25 <f4 / f5<-0.70 (23)-1.8 <f2 / f5<-0.9 (24)-0.40<(f4 / f)+(f5 / f)<-0.05 however, 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 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 T3: the distance on the optical axis X from the image-side surface of the third lens L3 to the object-side surface of the fourth lens L4 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 f5: focal length of the fifth lens L5 r1: paraxial radius of curvature of the object side surface of the first lens L1 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 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.

[0095] Moreover, the imaging lens of this embodiment exerts more preferable effects by satisfying the following conditional expressions (1a) to (24a). (1a)-300 mm <r1×r2 / f1<-2 mm (2a) -1.70 mm -1 <r3 / r7 / D2<-0.65 mm -1 (3a)25 <r5 / T2<110 (4a)-1.2 <r9 / f5<-0.8 (5a)20<νd5<32 (6a)-52.0 <r4 / T2<-9.5 (7a)-730 <r7 / (T3-T2)<-13 (8a)-19.5 mm -1 <(r2 / r3 / r7)×100<-8.0 mm -1 (9a)-30.0 <r8 / T4<-7.5 (10a)-9.5<(D1 / f1)×100<-5.3 (11a)-5.4 <f5 / D5<-2.8 (12a)4 <r1 / f<330 (13a)3.2 <r2 / T1<10.5 (14a)0.6 mm -1 <(r5 / r6 / r1)×100<33.0 mm -1 (15a) 0.5<(r2 / r1)×100<24.0 (16a)-1.25 mm -1 <r2 / r5 / r8<-0.35 mm -1 (17a)1.3 <r5 / r2<4.5 (18a) 0.7 <r6 / r2<1.6 (19a) 0.85 <f3 / f1<2.05 (20a)0.5 <f4 / f<0.8 (21a)-1.07 <f5 / f<-0.55 (22a)-1.00 <f4 / f5<-0.71 (23a)-1.50 <f2 / f5<-0.95 (24a)-0.35<(f4 / f)+(f5 / f)<-0.10 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 (24a) may be applied to the corresponding conditional expressions (1) to (24).

[0096] 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, A16, A18, and A20 are aspheric coefficients.

[0097]

number

[0098] 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.

[0099] Example 1

[0100] Basic lens data is shown in Table 1 below.

[0101] [Table 1]

[0102] The imaging lens of Example 1 achieves a total length to diagonal ratio of 0.83 and an F-number of 2.28. Also, as shown in Table 14, the imaging lens satisfies conditional expressions (1) to (24).

[0103] 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 (solid line) at the sagittal image plane S and the amount of aberration for the d-line (broken line) at the tangential image plane T (the same applies to FIGS. 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, and 26). As shown in FIG. 2, it can be seen that each aberration is well corrected.

[0104] Example 2

[0105] Basic lens data is shown in Table 2 below.

[0106] [Table 2]

[0107] The imaging lens of Example 2 achieves a total length to diagonal ratio of 0.82 and an F-number of 2.28. Also, as shown in Table 14, it satisfies conditional expressions (1) to (24).

[0108] 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.

[0109] Example 3

[0110] Basic lens data is shown in Table 3 below.

[0111] [Table 3]

[0112] The imaging lens of Example 3 achieves a total length to diagonal ratio of 0.82 and an F-number of 2.28. Also, as shown in Table 14, the imaging lens satisfies conditional expressions (1) to (24).

[0113] Fig. 6 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 3. As shown in Fig. 6, it can be seen that each aberration is well corrected.

[0114] Example 4

[0115] Basic lens data is shown in Table 4 below.

[0116] [Table 4]

[0117] The imaging lens of Example 4 achieves a total length to diagonal ratio of 0.82 and an F-number of 2.28. Also, as shown in Table 14, it satisfies conditional expressions (1) to (24).

[0118] Fig. 8 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 4. As shown in Fig. 8, it can be seen that each aberration is well corrected.

[0119] Example 5

[0120] Basic lens data is shown in Table 5 below.

[0121] [Table 5]

[0122] The imaging lens of Example 5 achieves a total length to diagonal ratio of 0.82 and an F-number of 2.28. Also, as shown in Table 14, the imaging lens satisfies conditional expressions (1) to (24).

[0123] Fig. 10 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 5. As shown in Fig. 10, it can be seen that each aberration is well corrected.

[0124] Example 6

[0125] Basic lens data is shown in Table 6 below.

[0126] [Table 6]

[0127] The imaging lens of Example 6 achieves a total length to diagonal ratio of 0.82 and an F-number of 2.28. Also, as shown in Table 14, it satisfies conditional expressions (1) to (24).

[0128] Fig. 12 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 6. As shown in Fig. 12, it can be seen that each aberration is well corrected.

[0129] Example 7

[0130] Basic lens data is shown in Table 7 below.

[0131] [Table 7]

[0132] The imaging lens of Example 7 achieves a total length to diagonal ratio of 0.81 and an F-number of 2.28. Also, as shown in Table 14, it satisfies conditional expressions (1) to (24).

[0133] Fig. 14 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 7. As shown in Fig. 14, it can be seen that each aberration is well corrected.

[0134] Example 8

[0135] Basic lens data is shown in Table 8 below.

[0136] [Table 8]

[0137] The imaging lens of Example 8 achieves a total length to diagonal ratio of 0.82 and an F-number of 2.23. Also, as shown in Table 14, the imaging lens satisfies conditional expressions (1) to (24).

[0138] Fig. 16 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 8. As shown in Fig. 16, it can be seen that each aberration is well corrected.

[0139] Example 9

[0140] Basic lens data is shown in Table 9 below.

[0141] [Table 9]

[0142] The imaging lens of Example 9 achieves a total length to diagonal ratio of 0.82 and an F-number of 2.23. Also, as shown in Table 14, the imaging lens satisfies conditional expressions (1) to (24).

[0143] Fig. 18 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 9. As shown in Fig. 18, it can be seen that each aberration is well corrected.

[0144] Example 10

[0145] Basic lens data is shown in Table 10 below.

[0146] [Table 10]

[0147] The imaging lens of Example 10 achieves a total length to diagonal ratio of 0.82 and an F-number of 2.23. Also, as shown in Table 14, the imaging lens satisfies conditional expressions (1) to (24).

[0148] Fig. 20 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 10. As shown in Fig. 20, it can be seen that each aberration is well corrected.

[0149] Example 11

[0150] Basic lens data is shown in Table 11 below.

[0151] [Table 11]

[0152] The imaging lens of Example 11 achieves a total length to diagonal ratio of 0.82 and an F-number of 2.23. Also, as shown in Table 14, the imaging lens satisfies conditional expressions (1) to (24).

[0153] Fig. 22 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 11. As shown in Fig. 22, it is clear that each aberration is well corrected.

[0154] Example 12

[0155] Basic lens data is shown in Table 12 below.

[0156] [Table 12]

[0157] The imaging lens of Example 12 achieves a total length to diagonal ratio of 0.82 and an F-number of 2.31. Also, as shown in Table 14, the imaging lens satisfies conditional expressions (1) to (24).

[0158] Fig. 24 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 12. As shown in Fig. 24, it is clear that each aberration is well corrected.

[0159] Example 13

[0160] Basic lens data is shown in Table 13 below.

[0161] [Table 13]

[0162] The imaging lens of Example 13 achieves a total length to diagonal ratio of 0.83 and an F-number of 2.20. Also, as shown in Table 14, the imaging lens satisfies conditional expressions (1) to (24).

[0163] Fig. 26 shows the spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 13. As shown in Fig. 26, it is clear that each aberration is well corrected.

[0164] Table 14 shows the values ​​of conditional expressions (1) to (24) according to Examples 1 to 13.

[0165] [Table 14] [Industrial Applicability]

[0166] When the imaging lens according to the present invention is applied to a product equipped with a camera function, it is possible to contribute to a reduction in the height and F-number of the camera, and to improve the performance. [Explanation of symbols]

[0167] 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 negative refractive power; a second lens having a positive refractive power; a third lens having a negative refractive power; a fourth lens having a positive refractive power; and a fifth lens having a negative refractive power, the first lens has a paraxial concave surface on the image side, the fifth lens has a paraxial concave surface on the image side, An imaging lens characterized by satisfying the following conditional expressions (1), (2), (3), (4), (5') and (9): (1) -400mm<r1×r2 / f1<-1mm <h2 style=";text-align:left;direction:ltr">(2) -2.00mm<h2 style=";text-align:left;direction:ltr"> －１ <h2 style=";text-align:left;direction:ltr"> 25665 ...<h2 style=";text-align:left;direction:ltr"> －１ (3) 20<r5 / T2<120 (4) -1.50<r9 / f5<-0.65 (5') 25.59≦νd5<36 (9) -40<r8 / T4<-7 however, r1: paraxial radius of curvature of the object side surface of the first lens r2: paraxial radius of curvature of the image side surface of the first lens f1: focal length of the first lens 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 r5: paraxial radius of curvature of the object side surface of the third 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 r9: paraxial radius of curvature of the object side surface of the fifth lens f5: focal length of the fifth lens νd5: Abbe number of the fifth lens for the d line r8: paraxial radius of curvature of the image side surface of the fourth lens 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

2. 2. The imaging lens according to claim 1, wherein the following conditional expression (6) is satisfied: (6) -65.0<r4 / T2<-7.3 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

3. 2. The imaging lens according to claim 1, wherein the following conditional expression (7) is satisfied: (7) -875<r7 / (T3-T2)<-10 however, r7: paraxial radius of curvature of the object side surface of the fourth lens T3: the distance on the optical axis from the image side surface of the third lens to the object side surface of the fourth 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

4. 2. The imaging lens according to claim 1, wherein the following conditional expression (8) is satisfied: <h2 style=";text-align:left;direction:ltr">(8)-20.5mm<h2 style=";text-align:left;direction:ltr"> －１ <h2 style=";text-align:left;direction:ltr"> <(r2 / r3 / r7)×1100<-6.5mm<h2 style=";text-align:left;direction:ltr"> －１ however, r2: paraxial radius of curvature of the image side surface of the first lens 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

5. 2. The imaging lens according to claim 1, wherein the following conditional expression (10) is satisfied: (10) -10.5<(D1 / f1)×100<-5.0 however, D1: Thickness of the first lens on the optical axis f1: focal length of the first lens

Images