阅读说明：本技术 摄像镜头 (Camera lens ) 是由 黄志宇 于 2020-12-03 设计创作，主要内容包括：本发明提供一种摄像镜头,其能够满足低背以及低F值的要求,并且具有良好的光学特性。该摄像镜头,从物侧朝向像侧依次包括：第一透镜,呈在近轴区凸面朝向物侧的弯月形状,具有正的光焦度；第二透镜,在近轴区具有正的光焦度；第三透镜,在近轴区具有负的光焦度；第四透镜,在近轴区具有正的光焦度；第五透镜,其双面形成为非球面；以及第六透镜,在近轴区凹面朝向像侧,具有负的光焦度；满足预定条件式。(The invention provides an imaging lens which can meet the requirements of low back and low F value and has good optical characteristics. The imaging lens includes, in order from an object side to an image side: a first lens having a meniscus shape with a convex surface facing the object side in a paraxial region, and having a positive refractive power; a second lens having a positive focal power in a paraxial region; a third lens having a negative focal power in a paraxial region; a fourth lens having a positive focal power in a paraxial region; a fifth lens, both surfaces of which are formed to be aspherical; and a sixth lens element having a negative refractive power, the concave surface of which faces the image side in the paraxial region; the predetermined conditional expression is satisfied.)

1. An imaging lens includes, in order from an object side to an image side:

a first lens having a meniscus shape with a convex surface facing the object side in a paraxial region, and having a positive refractive power;

a second lens having a positive focal power in a paraxial region;

a third lens having a negative focal power in a paraxial region;

a fourth lens having a positive focal power in a paraxial region;

a fifth lens, both surfaces of which are formed to be aspherical; and

a sixth lens element having a negative refractive power and a concave surface facing the image side in the paraxial region; the following conditional expressions (1) and (2) are satisfied:

(1)0.30＜f1/f4＜1.85

(2)-3.30＜r6/f＜-0.70

wherein the content of the first and second substances,

f 1: the focal length of the first lens is such that,

f 4: the focal length of the fourth lens element is,

r 6: the paraxial radius of curvature of the image-side surface of the third lens,

f: the focal length of the whole system of the camera lens.

2. The imaging lens according to claim 1, characterized in that the following conditional expression (3) is satisfied:

(3)15.00＜νd6＜36.00

wherein the content of the first and second substances,

ν d 6: the dispersion coefficient of the sixth lens with respect to the d-line.

3. The imaging lens according to claim 1, characterized in that the following conditional expression (4) is satisfied:

(4)1.50＜(T2/f2)×100＜5.50

wherein the content of the first and second substances,

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,

f 2: focal length of the second lens.

4. The imaging lens according to claim 1, characterized in that the following conditional expression (5) is satisfied:

(5)-12.50＜r6/r12＜-3.20

wherein the content of the first and second substances,

r 6: the paraxial radius of curvature of the image-side surface of the third lens,

r 12: a paraxial radius of curvature of an image-side surface of the sixth lens.

5. The imaging lens according to claim 1, characterized in that the following conditional expression (6) is satisfied:

(6)-3.50＜r8/r11＜-1.10

wherein the content of the first and second substances,

r 8: the paraxial radius of curvature of the image-side surface of the fourth lens,

r 11: paraxial radius of curvature of the object side of the sixth lens.

6. The imaging lens according to claim 1, characterized in that the following conditional expression (7) is satisfied:

(7)0.40＜r2/r4/r6＜1.20

wherein the content of the first and second substances,

r 2: a paraxial radius of curvature of an image-side surface of the first lens,

r 4: the paraxial radius of curvature of the image-side surface of the second lens,

r 6: a paraxial radius of curvature of an image-side surface of the third lens.

7. The imaging lens according to claim 1, characterized in that the following conditional expression (8) is satisfied:

(8)3.75＜|r3|/f＜70.00

wherein the content of the first and second substances,

r 3: the paraxial radius of curvature of the object-side surface of the second lens,

f: the focal length of the whole system of the camera lens.

Technical Field

The present invention relates to an imaging lens for forming an image of an object on a solid-state imaging element of a CCD sensor or a C-MOS sensor used in an imaging device.

Background

In recent years, camera functions have been widely mounted in various products such as home electric appliances, information terminal devices, and automobiles. In the future, development of a product incorporating a camera function is currently being carried out.

Imaging lenses mounted in such apparatuses are required to be small and high-resolution.

As a conventional imaging lens aiming at high performance, for example, an imaging lens of the following patent document 1 is known.

Patent document 1 (japanese unexamined patent application, first publication No. 109828355) discloses an imaging lens including, in order from an object side: a first lens; a second lens having a positive focal power; a third lens having a positive focal power; a fourth lens; a fifth lens; and a sixth lens; the relationship between the paraxial radius of curvature of the object-side surface of the second lens and the paraxial radius of curvature of the image-side surface of the second lens satisfies a certain condition.

Disclosure of Invention

Problems to be solved by the invention

When the lens structure described in patent document 1 is intended to achieve low back and low F-number, it is very difficult to correct aberrations in the peripheral portion, and good optical performance cannot be obtained.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an imaging lens having high resolution and capable of satisfactorily correcting aberrations while satisfying the requirements for low back and low F-number.

In the terms used in the present invention, the convex surface, concave surface, and flat surface of the lens surface mean shapes near the optical axis (paraxial). The optical power refers to the optical power near the optical axis (paraxial). The pole is a point on the aspheric surface other than the optical axis where the tangent plane perpendicularly intersects the optical axis. The total optical length is a distance on the optical axis from the object-side surface of the optical element located closest to the object side to the imaging surface. The optical total length and the back focal length are distances obtained by converting the thickness of an IR cut filter, a cover glass, or the like disposed between the imaging lens and the imaging surface into air.

Means for solving the problems

An imaging lens according to the present invention includes, in order from an object side to an image side: a first lens having a meniscus shape with a convex surface facing the object side in a paraxial region, and having a positive refractive power; a second lens having a positive focal power in a paraxial region; a third lens having a negative focal power in a paraxial region; a fourth lens having a positive focal power in a paraxial region; a fifth lens, both surfaces of which are formed to be aspherical; and a sixth lens having a negative refractive power and a concave surface facing the image side in the paraxial region.

By increasing the optical power, the first lens achieves low back. In addition, by having the convex surface facing the object side in the paraxial region, spherical aberration and distortion are suppressed.

The second lens realizes low back and well corrects astigmatism, curvature of field and distortion.

The third lens corrects chromatic aberration, coma, astigmatism, and distortion well.

The fourth lens realizes low back and excellently corrects astigmatism and distortion.

The fifth lens corrects astigmatism, curvature of field, and distortion well.

The sixth lens corrects chromatic aberration, astigmatism, curvature of field, and distortion well. In addition, the concave surface faces the image side in the paraxial region, thereby maintaining the low back and ensuring the back focus.

In the imaging lens having the above configuration, the image-side surface of the second lens element is preferably convex toward the image side in the paraxial region.

Astigmatism, curvature of field, and distortion can be corrected well by the image side surface of the second lens element being convex toward the image side in the paraxial region.

In the imaging lens having the above configuration, it is preferable that the image-side surface of the fourth lens element is convex toward the image side in the paraxial region.

Astigmatism and distortion can be corrected well by the image side surface of the fourth lens element being convex toward the image side in the paraxial region.

In the imaging lens having the above configuration, it is preferable that the object-side surface of the sixth lens element is convex toward the object side in the paraxial region.

Astigmatism, curvature of field, and distortion can be corrected well by the convex surface of the object side surface of the sixth lens element in the paraxial region toward the object side.

In the imaging lens having the above configuration, it is preferable that the object-side surface of the fifth lens element is formed into an aspherical surface having a pole at a position other than the optical axis.

The object side surface of the fifth lens is formed as an aspherical surface having a pole at a position other than the optical axis, whereby astigmatism and distortion can be corrected well.

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

The image side surface of the fifth lens is formed as an aspherical surface having a pole at a position other than the optical axis, whereby astigmatism and distortion can be corrected satisfactorily.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (1) is satisfied,

(1)0.30＜f1/f4＜1.85

wherein the content of the first and second substances,

f 1: the focal length of the first lens is such that,

f 4: focal length of the fourth lens.

The conditional expression (1) defines the relationship between the focal length of the first lens and the focal length of the fourth lens in an appropriate range. By satisfying the range of the conditional expression (1), the power of the first lens and the power of the fourth lens can be appropriately balanced. As a result, the lower back can be achieved, and spherical aberration, astigmatism, and distortion can be corrected well.

In the imaging lens having the above configuration, it is preferable that the following conditional expression (2) is satisfied,

(2)-3.30＜r6/f＜-0.70

wherein the content of the first and second substances,

r 6: the paraxial radius of curvature of the image-side surface of the third lens,

f: the focal length of the whole system of the camera lens.

The conditional expression (2) defines the paraxial radius of curvature of the image-side surface of the third lens element within an appropriate range. By satisfying the range of conditional expression (2), coma, astigmatism, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (3) is satisfied,

(3)15.00＜νd6＜36.00

wherein the content of the first and second substances,

ν d 6: the dispersion coefficient of the sixth lens with respect to the d-line.

Conditional expression (3) defines the dispersion coefficient of the sixth lens with respect to the d-line within an appropriate range. By satisfying the range of the conditional expression (3), chromatic aberration can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (4) is satisfied,

(4)1.50＜(T2/f2)×100＜5.50

wherein the content of the first and second substances,

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,

f 2: focal length of the second lens.

Conditional expression (4) defines the relationship between the distance on the optical axis from the image-side surface of the second lens to the object-side surface of the third lens and the focal length of the second lens in an appropriate range. By satisfying the range of the conditional expression (4), the reduction in the back can be achieved, the power of the second lens is an appropriate value, and astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (5) is satisfied,

(5)-12.50＜r6/r12＜-3.20

wherein the content of the first and second substances,

r 6: the paraxial radius of curvature of the image-side surface of the third lens,

r 12: a paraxial radius of curvature of an image-side surface of the sixth lens.

The conditional expression (5) defines the relationship between the paraxial radius of curvature of the image-side surface of the third lens element and the paraxial radius of curvature of the image-side surface of the sixth lens element in an appropriate range. By satisfying the range of conditional expression (5), coma, astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (6) is satisfied,

(6)-3.50＜r8/r11＜-1.10

wherein the content of the first and second substances,

r 8: the paraxial radius of curvature of the image-side surface of the fourth lens,

r 11: paraxial radius of curvature of the object side of the sixth lens.

Conditional expression (6) defines the relationship between the paraxial radius of curvature of the image-side surface of the fourth lens element and the paraxial radius of curvature of the object-side surface of the sixth lens element in an appropriate range. By satisfying the range of conditional expression (6), astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (7) is satisfied,

(7)0.40＜r2/r4/r6＜1.20

wherein the content of the first and second substances,

r 2: a paraxial radius of curvature of an image-side surface of the first lens,

r 4: the paraxial radius of curvature of the image-side surface of the second lens,

r 6: a paraxial radius of curvature of an image-side surface of the third lens.

Conditional expression (7) defines the relationship between the paraxial radius of curvature of the image-side surface of the first lens and the paraxial radius of curvature of the image-side surface of the second lens and the paraxial radius of curvature of the image-side surface of the third lens within an appropriate range. By satisfying the range of conditional expression (7), coma, astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (8) is satisfied,

(8)3.75＜|r3|/f＜70.00

wherein the content of the first and second substances,

r 3: the paraxial radius of curvature of the object-side surface of the second lens,

f: the focal length of the whole system of the camera lens.

The conditional expression (8) specifies the paraxial radius of curvature of the object-side surface of the second lens within an appropriate range. By satisfying the range of conditional expression (8), astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (9) is satisfied,

(9)-2.15＜r4/f＜-1.00

wherein the content of the first and second substances,

r 4: the paraxial radius of curvature of the image-side surface of the second lens,

f: the focal length of the whole system of the camera lens.

The conditional expression (9) specifies the paraxial radius of curvature of the image-side surface of the second lens within an appropriate range. By satisfying the range of conditional expression (9), astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (10) is satisfied,

(10)4.00＜(T1/f1)×100＜11.00

wherein the content of the first and second substances,

t1: the distance on the optical axis from the image side surface of the first lens to the object side surface of the second lens,

f 1: the focal length of the first lens.

The conditional expression (10) defines a relationship between a distance on the optical axis from the image-side surface of the first lens to the object-side surface of the second lens and the focal length of the first lens in an appropriate range. By satisfying the range of the conditional expression (10), reduction in the back can be achieved, and spherical aberration and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (11) is satisfied,

(11)1.50＜T2/T4＜7.25

wherein the content of the first and second substances,

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,

t4: a distance on the optical axis from the image-side surface of the fourth lens to the object-side surface of the fifth lens.

Conditional expression (11) specifies a relationship between a distance on the optical axis from the image-side surface of the second lens to the object-side surface of the third lens and a distance on the optical axis from the image-side surface of the fourth lens to the object-side surface of the fifth lens within an appropriate range. By satisfying the range of conditional expression (11), lowering of the back can be achieved, and coma, astigmatism, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (12) is satisfied,

(12)0.70＜f1/f＜1.95

wherein the content of the first and second substances,

f 1: the focal length of the first lens is such that,

f: the focal length of the whole system of the camera lens.

Conditional expression (12) specifies the focal length of the first lens in an appropriate range. By satisfying the range of conditional expression (12), reduction in the back can be achieved, and spherical aberration and distortion can be corrected well.

In the imaging lens having the above configuration, it is preferable that the following conditional expression (13) is satisfied,

(13)0.30＜f1/f2＜0.95

wherein the content of the first and second substances,

f 1: the focal length of the first lens is such that,

f 2: focal length of the second lens.

Conditional expression (13) specifies the relationship between the focal length of the first lens and the focal length of the second lens in an appropriate range. By satisfying the range of the conditional expression (13), the power of the first lens and the power of the second lens can be appropriately balanced. As a result, the lower back can be achieved, and spherical aberration, astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (14) is satisfied,

(14)-2.00＜f3/f4＜-0.70

wherein the content of the first and second substances,

f 3: the focal length of the third lens is such that,

f 4: focal length of the fourth lens.

Conditional expression (14) specifies the relationship between the focal length of the third lens and the focal length of the fourth lens in an appropriate range. By satisfying the range of the conditional expression (14), the power of the third lens and the power of the fourth lens can be appropriately balanced. As a result, coma, astigmatism, and distortion can be corrected well.

In the imaging lens having the above configuration, it is preferable that the following conditional expression (15) is satisfied,

(15)-40.00＜f6/f1＜-0.60

wherein the content of the first and second substances,

f 6: the focal length of the sixth lens element,

f 1: the focal length of the first lens.

Conditional expression (15) specifies the relationship between the focal length of the sixth lens and the focal length of the first lens in an appropriate range. By satisfying the range of the conditional expression (15), the power of the sixth lens and the power of the first lens can be appropriately balanced. As a result, the lower back can be achieved, and chromatic aberration, spherical aberration, astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (16) is satisfied,

(16)-7.50＜r2/r4＜-1.55

wherein the content of the first and second substances,

r 2: a paraxial radius of curvature of an image-side surface of the first lens,

r 4: a paraxial radius of curvature of an image-side surface of the second lens.

The conditional expression (16) defines the relationship between the paraxial radius of curvature of the image-side surface of the first lens and the paraxial radius of curvature of the image-side surface of the second lens within an appropriate range. By satisfying the range of conditional expression (16), astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (17) is satisfied,

(17)20.00＜r2/T2＜160.00

wherein the content of the first and second substances,

r 2: a paraxial radius of curvature of an image-side surface of the first lens,

t2: a distance on the optical axis from the image-side surface of the second lens to the object-side surface of the third lens.

The conditional expression (17) defines a relationship between the paraxial radius of curvature of the image-side surface of the first lens and the distance on the optical axis from the image-side surface of the second lens to the object-side surface of the third lens in an appropriate range. By satisfying the range of conditional expression (17), astigmatism and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (18) is satisfied,

(18)2.00＜|r3|/f2＜22.00

wherein the content of the first and second substances,

r 3: the paraxial radius of curvature of the object-side surface of the second lens,

f 2: focal length of the second lens.

The conditional expression (18) defines the relationship between the paraxial radius of curvature of the object-side surface of the second lens and the focal length of the second lens in an appropriate range. By satisfying the range of the conditional expression (18), reduction in the back can be achieved, and astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above configuration, it is preferable that the following conditional expression (19) is satisfied,

(19)0.30＜r4/r6＜2.20

wherein the content of the first and second substances,

r 4: the paraxial radius of curvature of the image-side surface of the second lens,

r 6: a paraxial radius of curvature of an image-side surface of the third lens.

The conditional expression (19) defines the relationship between the paraxial radius of curvature of the image-side surface of the second lens and the paraxial radius of curvature of the image-side surface of the third lens within an appropriate range. By satisfying the range of conditional expression (19), coma, astigmatism, curvature of field, and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (20) is satisfied,

(20)3.90＜|r7|/f

wherein the content of the first and second substances,

r 7: the paraxial radius of curvature of the object-side surface of the fourth lens,

f: the focal length of the whole system of the camera lens.

The conditional expression (20) specifies the paraxial radius of curvature of the object-side surface of the fourth lens element within an appropriate range. By satisfying the range of conditional expression (20), astigmatism and distortion can be corrected well.

In the imaging lens having the above configuration, it is preferable that the following conditional expression (21) is satisfied,

(21)-1.05＜r8/f＜-0.50

wherein the content of the first and second substances,

r 8: the paraxial radius of curvature of the image-side surface of the fourth lens,

f: the focal length of the whole system of the camera lens.

The conditional expression (21) specifies the paraxial radius of curvature of the image-side surface of the fourth lens element within an appropriate range. By satisfying the range of the conditional expression (21), astigmatism and distortion can be corrected well.

In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (22) is satisfied,

(22)0.30＜r11/r12＜2.00

wherein the content of the first and second substances,

r 11: the paraxial radius of curvature of the object-side surface of the sixth lens,

r 12: a paraxial radius of curvature of an image-side surface of the sixth lens.

The conditional expression (22) defines a relationship between the paraxial radius of curvature of the object-side surface of the sixth lens element and the paraxial radius of curvature of the image-side surface of the sixth lens element in an appropriate range. By satisfying the range of the conditional expression (22), astigmatism, curvature of field, and distortion can be corrected well.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention can provide an imaging lens that satisfies the requirements for a low back and a low F value in a balanced manner, corrects each aberration well, and has a high resolution.

Drawings

Fig. 1 is a diagram showing a schematic configuration of an imaging lens according to embodiment 1 of the present invention.

Fig. 2 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to embodiment 1 of the present invention.

Fig. 3 is a diagram showing a schematic configuration of an imaging lens according to embodiment 2 of the present invention.

Fig. 4 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to embodiment 2 of the present invention.

Fig. 5 is a diagram showing a schematic configuration of an imaging lens according to embodiment 3 of the present invention.

Fig. 6 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to embodiment 3 of the present invention.

Fig. 7 is a diagram showing a schematic configuration of an imaging lens according to embodiment 4 of the present invention.

Fig. 8 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to example 4 of the present invention.

Fig. 9 is a diagram showing a schematic configuration of an imaging lens according to embodiment 5 of the present invention.

Fig. 10 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to example 5 of the present invention.

Fig. 11 is a diagram showing a schematic configuration of an imaging lens according to embodiment 6 of the present invention.

Fig. 12 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to example 6 of the present invention.

Fig. 13 is a diagram showing a schematic configuration of an imaging lens according to embodiment 7 of the present invention.

Fig. 14 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to example 7 of the present invention.

Fig. 15 is a diagram showing a schematic configuration of an imaging lens according to embodiment 8 of the present invention.

Fig. 16 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to example 8 of the present invention.

Fig. 17 is a diagram showing a schematic configuration of an imaging lens according to embodiment 9 of the present invention.

Fig. 18 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to example 9 of the present invention.

Fig. 19 is a diagram showing a schematic configuration of an imaging lens according to embodiment 10 of the present invention.

Fig. 20 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to example 10 of the present invention.

Description of the reference numerals

ST: an aperture diaphragm,

L1: a first lens element,

L2: a second lens element,

L3: a third lens element,

L4: a fourth lens element,

L5: a fifth lens element,

L6: a sixth lens element,

ih: maximum image height,

IR: a filter, a,

IMG: and an image pickup surface.

Detailed Description

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

Fig. 1, 3, 5, 7, 9, 11, 13, 15, 17, and 19 are schematic configuration diagrams of imaging lenses according to embodiments 1 to 10 of the present invention, respectively.

The imaging lens of this embodiment includes, in order from an object side to an image side: a first lens L1 having a meniscus shape with a convex surface facing the object side in the paraxial region, and having a positive power; a second lens L2 having a positive power in the paraxial region; a third lens L3 having a negative power in the paraxial region; a fourth lens L4 having a positive power in the paraxial region; a fifth lens L5 whose both surfaces are formed to be aspherical; and a sixth lens L6 having a concave surface facing the image side in the paraxial region and having negative power.

A filter IR such as an infrared cut filter or a cover glass is disposed between the sixth lens L6 and the imaging surface IMG (i.e., the imaging surface of the imaging element). In addition, the filter IR can be omitted.

By disposing the aperture stop ST on the object side of the first lens L1, it is easy to correct each aberration and control the incident angle of light with a high image height to the image pickup element.

The first lens L1 has a positive power and has a meniscus shape with a convex surface facing the object side and a concave surface facing the image side in the paraxial region. Therefore, by increasing the power, the low back is achieved, and astigmatism and distortion are suppressed. In addition, by having the convex surface facing the object side in the paraxial region, spherical aberration and distortion are suppressed.

The second lens L2 has a positive power and has a meniscus shape with a concave surface facing the object side and a convex surface facing the image side in the paraxial region. Therefore, astigmatism, curvature of field, and distortion are corrected well while achieving low back. In addition, astigmatism, curvature of field, and distortion are corrected well by the convex surface facing the image side in the paraxial region.

As shown in embodiments 7, 8, 9, and 10 illustrated in fig. 13, 15, 17, and 19, the second lens L2 may have a biconvex shape with a convex surface facing the object side and a convex surface facing the image side in the paraxial region. In this case, since both surfaces have positive refractive power, lowering of the back is facilitated.

The third lens L3 has a negative refractive power and has a meniscus shape with a concave surface facing the object side and a convex surface facing the image side in the paraxial region. Therefore, chromatic aberration, coma, astigmatism, and distortion are corrected well.

The fourth lens L4 has a positive refractive power and has a biconvex shape with a convex surface facing the object side and a convex surface facing the image side in the paraxial region. Therefore, astigmatism and distortion are corrected well while achieving low back. In addition, astigmatism and distortion are corrected well by the convex surface facing the image side in the paraxial region.

In addition, as in embodiment 10 shown in fig. 19, the fourth lens element L4 may have a meniscus shape with a concave surface facing the object side and a convex surface facing the image side in the paraxial region. In this case, the incident angle of the light beam on the fourth lens L4 can be appropriately controlled, and astigmatism and distortion can be corrected satisfactorily.

The fifth lens L5 is shaped to have substantially no optical power, and has a shape facing the object side and the image side in the paraxial region plane. Therefore, astigmatism, curvature of field, and distortion are corrected well by forming both surfaces to be aspherical without affecting the focal length of the entire imaging lens system.

As shown in example 4 and example 6 shown in fig. 7 and 11, the refractive power of the fifth lens L5 may be a positive value. In this case, the low back is facilitated. As shown in example 5, example 7, and example 8 shown in fig. 9, 13, and 15, the refractive power of the fifth lens L5 may be negative. At this time, correction of chromatic aberration is facilitated.

In addition, as in embodiments 4 and 6 shown in fig. 7 and 11, the fifth lens L5 may have a biconvex shape with a convex surface facing the object side and a convex surface facing the image side in the paraxial region. In this case, since both surfaces have positive refractive power, lowering of the back is facilitated. In addition, as in embodiment 5 shown in fig. 9, the fifth lens L5 may have a biconcave shape in which the concave surface faces the object side and the concave surface faces the image side in the paraxial region. In this case, chromatic aberration can be corrected favorably by having negative refractive power on both surfaces. In addition, as in embodiments 7 and 8 illustrated in fig. 13 and 15, the fifth lens L5 may have a meniscus shape with a convex surface facing the object side and a concave surface facing the image side in the paraxial region. In this case, astigmatism and distortion can be corrected well.

The object-side surface of the fifth lens L5 is formed into an aspherical surface having a pole at a position other than the position on the optical axis X. Therefore, astigmatism and distortion are corrected well.

The image-side surface of the fifth lens L5 is formed into an aspherical surface having a pole at a position other than the position on the optical axis X. Therefore, astigmatism and distortion are corrected well.

The sixth lens L6 has a negative refractive power and has a meniscus shape with a convex surface facing the object side and a concave surface facing the image side in the paraxial region. Therefore, chromatic aberration, astigmatism, curvature of field, and distortion are corrected well. In addition, the concave surface faces the image side in the paraxial region, thereby maintaining the low back and ensuring the back focus.

In the imaging lens of the present embodiment, all of the first lens L1 to the sixth lens L6 are preferably configured by a single lens. The aspherical surface can be more used by being constituted by only a single lens. In the present embodiment, each aberration is corrected favorably by forming all lens surfaces to be appropriate aspherical surfaces. Further, since man-hours can be reduced as compared with the case of using a cemented lens, it can be manufactured at low cost.

In addition, the imaging lens of the present embodiment is easy to manufacture by using a plastic material for all the lenses, and can be mass-produced at low cost.

The lens material used is not limited to a plastic material. By using a glass material, higher performance can be expected. Further, all lens surfaces are preferably formed to be aspherical, but a spherical surface which can be easily manufactured may be used depending on the required performance.

The imaging lens in the present embodiment satisfies the following conditional expressions (1) to (22), and exhibits a preferable effect.

(1)0.30＜f1/f4＜1.85

(2)-3.30＜r6/f＜-0.70

(3)15.00＜νd6＜36.00

(4)1.50＜(T2/f2)×100＜5.50

(5)-12.50＜r6/r12＜-3.20

(6)-3.50＜r8/r11＜-1.10

(7)0.40＜r2/r4/r6＜1.20

(8)3.75＜|r3|/f＜70.00

(9)-2.15＜r4/f＜-1.00

(10)4.00＜(T1/f1)×100＜11.00

(11)1.50＜T2/T4＜7.25

(12)0.70＜f1/f＜1.95

(13)0.30＜f1/f2＜0.95

(14)-2.00＜f3/f4＜-0.70

(15)-40.00＜f6/f1＜-0.60

(16)-7.50＜r2/r4＜-1.55

(17)20.00＜r2/T2＜160.00

(18)2.00＜|r3|/f2＜22.00

(19)0.30＜r4/r6＜2.20

(20)3.90＜|r7|/f

(21)-1.05＜r8/f＜-0.50

(22)0.30＜r11/r12＜2.00

Wherein the content of the first and second substances,

ν d 6: the dispersion coefficient of the sixth lens L6 with respect to the d-line,

t1: the distance on the optical axis X from the image-side surface of the first lens L1 to the object-side surface of the second lens L2,

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: the focal length of the whole system of the camera lens,

f 1: the focal length of the first lens L1,

f 2: the focal length of the second lens L2,

f 3: the focal length of the third lens L3,

f 4: the focal length of the fourth lens L4,

f 6: the focal length of the sixth lens L6,

r 2: the paraxial radius of curvature of the image-side surface of the first lens L1,

r 3: the paraxial radius of curvature of the object-side surface of the second lens L2,

r 4: the paraxial radius of curvature of the image-side surface of the second lens L2,

r 6: the paraxial radius of curvature of the image-side surface of the third lens L3,

r 7: the paraxial radius of curvature of the object-side surface of the fourth lens L4,

r 8: the paraxial radius of curvature of the image-side surface of the fourth lens L4,

r 11: the paraxial radius of curvature of the object side of the sixth lens L6,

r 12: paraxial radius of curvature of the image-side surface of the sixth lens L6.

Further, it is not necessary to satisfy all of the conditional expressions, and it is possible to obtain the operational effects corresponding to the respective conditional expressions by satisfying each conditional expression individually.

In addition, the imaging lens in the present embodiment satisfies the following conditional expressions (1a) to (22a), and exhibits a further advantageous effect.

(1a)0.80＜f1/f4＜1.75

(2a)-2.70＜r6/f＜-0.85

(3a)20.00＜νd6＜30.00

(4a)1.90＜(T2/f2)×100＜5.00

(5a)-10.50＜r6/r12＜-3.60

(6a)-2.90＜r8/r11＜-1.40

(7a)0.45＜r2/r4/r6＜1.00

(8a)4.25＜|r3|/f＜50.00

(9a)-1.80＜r4/f＜-1.20

(10a)5.00＜(T1/f1)×100＜9.00

(11a)2.50＜T2/T4＜6.60

(12a)1.10＜f1/f＜1.85

(13a)0.45＜f1/f2＜0.85

(14a)-1.65＜f3/f4＜-0.85

(15a)-33.00＜f6/f1＜-1.00

(16a)-6.00＜r2/r4＜-1.85

(17a)25.00＜r2/T2＜130.00

(18a)2.10＜|r3|/f2＜18.00

(19a)0.45＜r4/r6＜1.85

(20a)4.10＜|r7|/f＜230.00

(21a)-0.85＜r8/f＜-0.55

(22a)0.80＜r11/r12＜1.75

The symbols of the respective conditional expressions are the same as those described in the preceding paragraph.

In the present embodiment, the aspherical shape adopted for the aspherical surface of the lens surface is expressed by expression 1 when the axis in the optical axis direction is Z, the height in the direction orthogonal to the optical axis is H, the paraxial radius of curvature is R, the conic coefficient is k, and the aspherical coefficients are a4, a6, A8, a10, a12, a14, a16, a18, and a 20.

[ mathematical formula 1]

Next, an example of the imaging lens according to the present embodiment is shown. In each embodiment, F denotes a focal length of the entire imaging lens system, Fno denotes an F value, ω denotes a half field angle, ih denotes a maximum image height, and TTL denotes a total optical length. In addition, i denotes a surface number counted from the object side, r denotes a paraxial radius of curvature, d denotes a distance (surface interval) between lens surfaces on the optical axis, Nd denotes a refractive index of a d-line (reference wavelength), and vd denotes an abbe number with respect to the d-line. The aspherical surface is indicated by an asterisk symbol placed after the surface number i.

[ example 1]

The basic lens data are shown in table 1 below.

[ Table 1]

As shown in table 11, the imaging lens of example 1 satisfies conditional expressions (1) to (22).

Fig. 2 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 1. The spherical aberration diagram shows the amount of aberration for each wavelength of the F-line (486nm), d-line (588nm), and C-line (656 nm). The astigmatism diagrams show the amount of aberration of the d-line on the sagittal image plane S (solid line) and the amount of aberration of the d-line on the meridional image plane T (broken line), respectively (the same applies to fig. 4, 6, 8, 10, 12, 14, 16, 18, and 20). As shown in fig. 2, it is understood that each aberration is corrected well.

[ example 2]

The basic lens data are shown in table 2 below.

[ Table 2]

As shown in table 11, the imaging lens of example 2 satisfies conditional expressions (1) to (22).

Fig. 4 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens in example 2. As shown in fig. 4, it is understood that each aberration is corrected well.

[ example 3]

The basic lens data are shown in table 3 below.

[ Table 3]

As shown in table 11, the imaging lens of example 3 satisfies conditional expressions (1) to (22).

Fig. 6 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 3. As shown in fig. 6, it is understood that each aberration is corrected well.

[ example 4]

The basic lens data are shown in table 4 below.

[ Table 4]

As shown in table 11, the imaging lens of example 4 satisfies conditional expressions (1) to (22).

Fig. 8 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 4. As shown in fig. 8, it is understood that each aberration is corrected well.

[ example 5]

The basic lens data are shown in table 5 below.

[ Table 5]

As shown in table 11, the imaging lens of example 5 satisfies conditional expressions (1) to (22).

Fig. 10 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 5. As shown in fig. 10, it is understood that each aberration is corrected well.

[ example 6]

The basic lens data are shown in table 6 below.

[ Table 6]

As shown in table 11, the imaging lens of example 6 satisfies conditional expressions (1) to (22).

Fig. 12 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 6. As shown in fig. 12, it is understood that each aberration is corrected well.

[ example 7]

The basic lens data are shown in table 7 below.

[ Table 7]

As shown in table 11, the imaging lens of example 7 satisfies conditional expressions (1) to (22).

Fig. 14 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens in example 7. As shown in fig. 14, it is understood that each aberration is corrected well.

[ example 8]

The basic lens data are shown in table 8 below.

[ Table 8]

As shown in table 11, the imaging lens of example 8 satisfies conditional expressions (1) to (22).

Fig. 16 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 8. As shown in fig. 16, it is understood that each aberration is corrected well.

[ example 9]

The basic lens data are shown in table 9 below.

[ Table 9]

As shown in table 11, the imaging lens of example 9 satisfies conditional expressions (1) to (22).

Fig. 18 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 9. As shown in fig. 18, it is understood that each aberration is corrected well.

[ example 10]

The basic lens data are shown in table 10 below.

[ Table 10]

As shown in table 11, the imaging lens of example 10 satisfies conditional expressions (1) to (22).

Fig. 20 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 10. As shown in fig. 20, it is understood that each aberration is corrected well.

Table 11 shows values of conditional expressions (1) to (22) according to examples 1 to 10.

[ Table 11]

Industrial applicability

When the imaging lens according to the present invention is applied to a product having a camera function, the camera can contribute to a reduction in the back and F-number of the camera, and can achieve a high performance of the camera.