CN114791660A - camera lens - Google Patents

Abstract

The present invention provides an imaging lens, which can meet the requirements of low F value and has good optical characteristics. The imaging lens, from the object side to the image side, includes: a first lens L1 with positive refractive power; a second lens L2; a third lens L3; and a fourth lens L4; the first lens is in the paraxial region The convex surface faces the object side; the concave surface of the third lens L3 faces the image side in the paraxial region; the predetermined conditional expression is satisfied.

Description

camera lens

technical field

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

Background technique

In recent years, camera functions have been widely installed in various products such as home appliances, information terminal equipment, and automobiles. It is predicted that in the future, the development of products incorporating camera functions will continue.

The imaging lens mounted in such a device needs to be small and high-resolution performance.

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

Patent Document 1 (JP2008-275783) discloses an imaging lens, the imaging lens includes sequentially from the object side: a first lens, having a positive refractive power, in the shape of a meniscus with a convex surface facing the object side; a second lens, Double concave shape;

a diaphragm; a third lens, in a biconvex shape; and a fourth lens, with negative power, in the shape of a meniscus with a concave surface toward the object side;

The relationship between the thickness of the entire system of the image reading lens and the distance on the optical axis of the third lens to the fourth lens satisfies certain conditions.

SUMMARY OF THE INVENTION

Invention to solve problem

When it is attempted to reduce the F value by the lens structure described in Patent Document 1, 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-mentioned problems, and an object of the present invention is to provide a high-resolution imaging lens that satisfies the demand for lowering the F-number in a balanced manner, and that satisfactorily corrects various aberrations.

In addition, regarding the term used in this invention, the convex surface, the concave surface, and the flat surface of a lens surface mean the shape of the vicinity of an optical axis (paraxial). The optical power refers to the optical power near the optical axis (paraxial). A pole is a point on an aspheric surface other than the optical axis where the tangent plane intersects perpendicularly to the optical axis. The total optical length refers to the distance on the optical axis from the object side surface of the optical element located on the most object side to the imaging surface. In addition, the total optical length and the back focus are distances obtained by air conversion for the thickness of an IR cut filter, a cover glass, or the like arranged between the imaging lens and the imaging surface.

means to solve the problem

The imaging lens of the present invention includes, in order from the object side to the image side: a first lens with positive refractive power, a convex surface in a paraxial region facing the object side; a second lens; a third lens, concave in the paraxial region facing the image side; and a fourth lens.

In the imaging lens having the above structure, the first lens has a positive refractive power, so that the low profile is realized.

In addition, spherical aberration, coma, astigmatism, field curvature, and distortion are suppressed by facing the object side convexly in the paraxial region.

In addition, the image side surface of the third lens is concave toward the image side in the paraxial region, and astigmatism, field curvature and distortion are well corrected.

In the imaging lens of the first structure described above, with respect to each refractive power, the first structure has a positive first lens, a negative second lens, a positive third lens, and a negative first lens in order from the object side to the image side. Four lenses.

In addition, in the imaging lens of the above-mentioned second configuration, with respect to each refractive power, the second configuration includes a positive first lens, a positive second lens, a negative third lens, a positive fourth lens.

In the imaging lens of the above-mentioned first structure, preferably, the first lens has a biconvex shape in the paraxial region. The first lens has a biconvex shape in the paraxial region, and has positive refractive power on both sides, so as to achieve low back and suppress spherical aberration, coma, astigmatism, field curvature and distortion.

In the above-mentioned imaging lens of the first structure, preferably, the second lens has a biconcave shape in the paraxial region. In addition, chromatic aberration, coma, astigmatism, field curvature, and distortion are well corrected by the second lens having a biconcave shape in the paraxial region.

In the imaging lens of the above-mentioned first structure, it is preferable that the third lens has a meniscus shape with a concave surface facing the image side in the paraxial region. Spherical aberration, coma, astigmatism, field curvature and distortion are well corrected by the third lens having a meniscus shape with a concave surface facing the image side in the paraxial region.

In the imaging lens of the above-mentioned first structure, it is preferable that the fourth lens has a meniscus shape with a convex surface facing the image side in the paraxial region. Chromatic aberration, coma, astigmatism, field curvature, and distortion are well corrected by the fourth lens in the shape of a meniscus whose convex surface faces the image side in the paraxial region.

In addition, in the imaging lens of the above-mentioned first structure, that is, the refractive powers are arranged in the order from the object side, positive, negative, positive, and negative, it is preferable that the shape of each lens is in the paraxial region from the object side, biconvex. shape, biconcave shape, meniscus shape with concave side toward the image side, and meniscus shape with convex side toward the image side.

In the imaging lens of the above-mentioned second structure, it is preferable that the first lens has a meniscus shape with a convex surface facing the object side in the paraxial region. Spherical aberration, coma, astigmatism, curvature of field and distortion are suppressed by the first lens having a meniscus shape with a convex surface facing the object side in the paraxial region. In addition, spherical aberration, coma aberration, and astigmatism can be favorably corrected by turning the concave surface toward the image side in the paraxial region.

In the above-mentioned imaging lens of the second structure, preferably, the second lens has a biconvex shape in the paraxial region. The second lens has a biconvex shape in the paraxial region, and has positive refractive power on both sides, so as to achieve low-background and excellent correction of spherical aberration, coma, astigmatism, field curvature and distortion.

In the above-mentioned imaging lens of the second structure, preferably, the third lens has a biconcave shape in the paraxial region. Chromatic aberration, coma, astigmatism, field curvature and distortion are well corrected by the third lens having a biconcave shape in the paraxial region.

In the imaging lens of the above-mentioned second structure, it is preferable that the fourth lens has a meniscus shape with a concave surface facing the image side in the paraxial region. In addition, coma, astigmatism, field curvature, and distortion are favorably corrected by the fourth lens having a meniscus shape with a concave surface facing the image side in the paraxial region.

In addition, in the imaging lens of the above-mentioned second structure, that is, a structure in which the refractive powers are arranged in order from the object side, positive, positive, negative, and positive, it is preferable that the shape of each lens is in order from the object side in the paraxial region, and the convex surface faces The meniscus shape on the object side, the biconvex shape, the biconcave shape, and the meniscus shape with the concave surface facing the image side.

In addition, in the imaging lenses of the first and second configurations described above, it is preferable that each lens surface is formed as an aspherical surface. By forming each lens surface as an aspherical surface, various aberrations are favorably corrected.

By adopting the above-described structure in the imaging lens of the present invention, the F-number is reduced to 4.0 or less.

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

(1) 13＜νd4＜34

in,

νd4: Dispersion coefficient of the fourth lens with respect to the d-line.

By satisfying the range of conditional expression (1), chromatic aberration can be favorably corrected.

In addition, in the imaging lens having the above-mentioned configuration, it is preferable that the following conditional expression (2) is satisfied:

(2) 0.3＜νd3/νd4＜2.0

in,

νd3: the dispersion coefficient of the third lens with respect to the d-line,

νd4: Dispersion coefficient of the fourth lens with respect to the d-line.

By satisfying the range of Conditional Expression (2), chromatic aberration can be favorably corrected.

In addition, in the imaging lens of the above-mentioned configuration, it is preferable to satisfy the following conditional expression (3),

(3) 0.25＜|r2/r3|＜0.85

in,

r2: the paraxial radius of curvature of the image side of the first lens,

r3: Paraxial radius of curvature of the object side surface of the second lens.

By satisfying the range of Conditional Expression (3), spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens of the above-mentioned configuration, it is preferable to satisfy the following conditional expression (4),

(4) 0.85＜|f4|/f＜3.85

f4: the focal length of the fourth lens,

f: The focal length of the entire system of the camera lens.

By satisfying the range of conditional expression (4), coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens of the above-mentioned configuration, it is preferable to satisfy the following conditional expression (5),

(5) 0.15＜|r2|/f＜0.55

in,

r2: the paraxial radius of curvature of the image side of the first lens,

f: The focal length of the entire system of the camera lens.

By satisfying the range of Conditional Expression (5), spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens of the above-mentioned configuration, it is preferable to satisfy the following conditional expression (6),

(6) 0.2＜|r3|/f＜1.2

in,

r3: paraxial radius of curvature of the object side of the second lens,

f: The focal length of the entire system of the camera lens.

By satisfying the range of Conditional Expression (6), astigmatism, curvature of field, and distortion can be favorably corrected.

In addition, in the imaging lens having the above structure, it is preferable to satisfy the following conditional expression (7),

(7) 0.5＜r6/|f3|＜6.0

in,

r6: paraxial radius of curvature of the image side of the third lens,

f3: The focal length of the third lens.

By satisfying the range of Conditional Expression (7), spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens having the above-mentioned structure, it is preferable to satisfy the following conditional expression (8),

(8) 9＜D3/|f3|)×100＜43

in,

D3: Thickness on the optical axis of the third lens,

f3: The focal length of the third lens.

By satisfying the range of Conditional Expression (8), lowering of the background is achieved, and spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected favorably.

In addition, in the imaging lens having the above-mentioned configuration, it is preferable to satisfy the following conditional expression (9),

(9) 0.1＜|f2|/f＜0.7

in,

f2: the focal length of the second lens,

f: The focal length of the entire system of the camera lens.

By satisfying the range of Conditional Expression (9), coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens of the above-mentioned structure, it is preferable to satisfy the following conditional expression (10),

(10) 0.1＜|f3|/f＜0.8

in,

f3: the focal length of the third lens,

f: The focal length of the entire system of the camera lens.

By satisfying the range of Conditional Expression (10), spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens having the above-mentioned structure, it is preferable to satisfy the following conditional expression (11),

(11) 13＜νd3＜34

in,

νd3: Dispersion coefficient of the third lens with respect to the d-line.

By satisfying the range of Conditional Expression (11), chromatic aberration can be corrected favorably.

In addition, in the imaging lens having the above structure, it is preferable to satisfy the following conditional expression (12),

(12) 0.1＜r1/f＜0.4

in,

r1: the paraxial radius of curvature of the object side of the first lens,

f: The focal length of the entire system of the camera lens.

By satisfying the range of Conditional Expression (12), spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens of the above-mentioned configuration, it is preferable to satisfy the following conditional expression (13),

(13) 0.3＜r1/|r2|＜1.5

in,

r1: the paraxial radius of curvature of the object side of the first lens,

r2: The paraxial radius of curvature of the image side surface of the first lens.

By satisfying the range of Conditional Expression (13), spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens having the above-mentioned structure, it is preferable to satisfy the following conditional expression (14),

(14) 0.2＜|r2/r8|＜1.8

in,

r2: the paraxial radius of curvature of the image side of the first lens,

r8: Paraxial radius of curvature of the image side surface of the fourth lens.

By satisfying the range of Conditional Expression (14), spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens having the above-mentioned configuration, it is preferable to satisfy the following conditional expression (15),

(15) 0.05＜|r2/f1|＜2.00

in,

r2: paraxial radius of curvature of the image side of the first lens,

f1: The focal length of the first lens.

By satisfying the range of Conditional Expression (15), spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens having the above structure, it is preferable to satisfy the following conditional expression (16), (16) 0.65<|r3/r7|<3.70

in,

r3: paraxial radius of curvature of the object side of the second lens,

r7: Paraxial radius of curvature of the object side surface of the fourth lens.

By satisfying the range of conditional expression (16), coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens having the above-mentioned configuration, it is preferable to satisfy the following conditional expression (17),

(17) 0.25＜|r5|/f＜0.80

in,

r5: paraxial radius of curvature of the object side of the third lens,

f: The focal length of the entire system of the camera lens.

By satisfying the range of Conditional Expression (17), spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens having the above-mentioned structure, it is preferable to satisfy the following conditional expression (18),

(18) 0.5＜|r5|/T3＜9.0

in,

r5: paraxial radius of curvature of the object side of the third 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.

By satisfying the range of Conditional Expression (18), lowering of the background is achieved, and spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens having the above-mentioned configuration, it is preferable to satisfy the following conditional expression (19),

(19) 0.05＜|r5|/r6＜1.60

in,

r5: paraxial radius of curvature of the object side of the third lens,

r6: Paraxial radius of curvature of the image side surface of the third lens.

By satisfying the range of Conditional Expression (19), spherical aberration, coma, astigmatism, curvature of field, and distortion can be favorably corrected.

In addition, in the imaging lens of the above-mentioned configuration, it is preferable to satisfy the following conditional expression (20),

(20) 0.2＜|r5/f3|＜2.0

in,

r5: paraxial radius of curvature of the object side of the third lens,

f3: The focal length of the third lens.

By satisfying the range of Conditional Expression (20), spherical aberration, coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens of the above-mentioned configuration, it is preferable to satisfy the following conditional expression (21),

(21) 0.2＜r6/f＜3.0

in,

r6: paraxial radius of curvature of the image side of the third lens,

f: The focal length of the entire system of the camera lens.

By satisfying the range of Conditional Expression (21), astigmatism, curvature of field, and distortion can be favorably corrected.

In addition, in the imaging lens of the above-mentioned configuration, it is preferable to satisfy the following conditional expression (22),

(22) 0.1＜|r7|/f＜0.8

in,

r7: paraxial radius of curvature of the object side of the fourth lens,

f: The focal length of the entire system of the camera lens.

By satisfying the range of Conditional Expression (22), coma, astigmatism, and distortion can be favorably corrected.

In addition, in the imaging lens of the above configuration, it is preferable to satisfy the following conditional expression (23),

(23) 0.2＜|r7|/(T3+bf)＜1.7

in,

r7: paraxial radius of curvature of the object side of the fourth lens,

T3: The distance on the optical axis from the image side of the third lens to the object side of the fourth lens,

bf: Back focal length.

By satisfying the range of Conditional Expression (23), lowering of the background can be achieved, and coma, astigmatism, and distortion can be favorably corrected.

In addition, in the imaging lens of the above-mentioned structure, it is preferable to satisfy the following conditional expression (24),

(24) 0.1＜|r7/r8|＜1.6

in,

r7: paraxial radius of curvature of the object side of the fourth lens,

r8: Paraxial radius of curvature of the image side surface of the fourth lens.

By satisfying the range of Conditional Expression (24), coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens having the above-mentioned structure, it is preferable to satisfy the following conditional expression (25),

(25) 6＜(D2/|f2|)×100＜61

in,

D2: Thickness on the optical axis of the second lens,

f2: The focal length of the second lens.

By satisfying the range of Conditional Expression (25), low background can be achieved, and coma, astigmatism, field curvature, and distortion can be favorably corrected.

In addition, in the imaging lens having the above-mentioned configuration, it is preferable to satisfy the following conditional expression (26),

(26) 0.05＜|f2/f4|＜0.75

in,

f2: the focal length of the second lens,

f4: The focal length of the fourth lens.

By satisfying the range of Conditional Expression (26), coma, astigmatism, field curvature, and distortion can be favorably corrected.

According to the present invention, a high-resolution imaging lens can be obtained that corrects various aberrations well.

Description of drawings

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

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

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

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

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

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

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

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

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

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

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

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

Detailed ways

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

FIG. 1 is a schematic configuration diagram of an imaging lens according to Example 1 of the first embodiment of the present invention. FIGS. 3 , 5 , 7 , 9 , and 11 show schematic configuration diagrams of imaging lenses according to Examples 2 to 6 of the second embodiment of the present invention, respectively.

As shown in the schematic structural diagram, the imaging lens of the present invention includes, in order from the object side to the image side: a first lens L1 having positive refractive power; a second lens L2; a third lens L3; and a fourth lens L4, The first lens L1 has a convex surface facing the object side in the paraxial region, and the third lens L3 has a concave surface facing the image side in the paraxial region.

A filter IR such as an infrared cut filter or a protective glass is arranged between the fourth lens L4 and the imaging surface IMG (ie, the imaging surface of the imaging element). In addition, the filter IR can be omitted.

Since the aperture stop ST is arranged on the object side of the first lens L1 , it is easy to correct various aberrations, and it is easy to suppress the angle at which the high image ray is incident on the imaging element.

[First Embodiment]

Hereinafter, the first embodiment according to the present invention will be described in detail with reference to FIG. 1 .

The first lens L1 has positive refractive power and has a biconvex shape in the paraxial region. Therefore, the double-sided positive refractive power is used to achieve low profile and suppress spherical aberration, coma, astigmatism, field curvature and distortion.

The second lens L2 has a negative refractive power and has a biconcave shape in the paraxial region. Therefore, chromatic aberration, coma, astigmatism, field curvature and distortion are well corrected.

The third lens L3 has positive refractive power and is in the shape of a meniscus whose concave surface faces the image side in the paraxial region. Therefore, spherical aberration, coma, astigmatism, field curvature and distortion are well corrected.

The fourth lens L4 has a negative refractive power and is in the shape of a meniscus whose convex surface faces the image side in the paraxial region. Therefore, chromatic aberration, coma, astigmatism, field curvature and distortion are well corrected.

[Second Embodiment]

Hereinafter, a second embodiment according to the present invention will be described in detail with reference to FIG. 3 .

The first lens L1 has a positive refractive power and has a meniscus shape with a convex surface facing the object side in the paraxial region. Therefore, spherical aberration, coma, astigmatism, field curvature and distortion are suppressed. In addition, spherical aberration, coma aberration, and astigmatism can be favorably corrected by turning the concave surface toward the image side in the paraxial region.

The second lens L2 has a positive refractive power and has a biconvex shape in the paraxial region. Therefore, spherical aberration, coma, astigmatism, field curvature and distortion are well corrected.

The third lens L3 has a negative refractive power and has a biconcave shape in the paraxial region. Therefore, chromatic aberration, coma, astigmatism, field curvature and distortion are well corrected.

The fourth lens L4 has positive refractive power and is in the shape of a meniscus whose concave surface faces the image side in the paraxial region. Therefore, coma, astigmatism, field curvature and distortion are well corrected.

In the imaging lens of the present embodiment, it is preferable that all the lenses of the first lens L1 to the fourth lens L4 be constituted by a single lens. Constituting only a single lens enables more use of aspheric surfaces. In the present embodiment, each aberration is favorably corrected by forming all the lens surfaces as appropriate aspheric surfaces. Moreover, compared with the case where a cemented lens is used, since the man-hour can be reduced, it can manufacture at low cost.

In addition, in the imaging lens of the present embodiment, it is preferable that all the lens surfaces are aspherical, but a spherical surface which is easy to manufacture may be adopted according to the required performance.

In addition, the imaging lens in this embodiment satisfies the following Conditional Expressions (1) to (26), thereby exhibiting better effects.

(1) 13＜νd4＜34

(2) 0.3＜νd3/νd4＜2.0

(3) 0.25＜|r2/r3|＜0.85

(4) 0.85＜|f4|/f＜3.85

(5) 0.15＜|r2|/f＜0.55

(6) 0.2＜|r3|/f＜1.2

(7) 0.5＜r6/|f3|＜6.0

(8) 9＜(D3/|f3|)×100＜43

(9) 0.1＜|f2|/f＜0.7

(10) 0.1＜|f3|/f＜0.8

(11) 13＜νd3＜34

(12) 0.1＜r1/f＜0.4

(13) 0.3＜r1/|r2|＜1.5

(14) 0.2＜|r2/r8|＜1.8

(15) 0.05＜|r2/f1|＜2.00

(16) 0.65＜|r3/r7|＜3.70

(17) 0.25＜|r5|/f＜0.80

(18) 0.5＜|r5|/T3＜9.0

(19) 0.05＜|r5|/r6＜1.60

(20) 0.2＜|r5/f3|＜2.0

(21) 0.2＜r6/f＜3.0

(22) 0.1＜|r7|/f＜0.8

(23) 0.2＜|r7|/(T3+bf)＜1.7

(24) 0.1＜|r7/r8|＜1.6

(25) 6＜(D2/|f2|)×100＜61

(26) 0.05＜|f2/f4|＜0.75

in,

νd3: the dispersion coefficient of the third lens L3 with respect to the d-line,

νd4: the dispersion coefficient of the fourth lens L4 with respect to the d-line,

D2: the thickness on the optical axis X of the second lens L2,

D3: the thickness on the optical axis X of the third lens L3,

T3: the distance on the optical axis X from the image side of the third lens L3 to the object side of the fourth lens L4,

bf: back focal length,

f: The focal length of the entire system of the camera lens,

f1: the focal length of the first lens L1,

f2: the focal length of the second lens L2,

f3: the focal length of the third lens L3,

f4: the focal length of the fourth lens L4,

r1: the paraxial radius of curvature of the object side surface of the first lens L1,

r2: the paraxial radius of curvature of the image side surface of the first lens L1,

r3: the paraxial radius of curvature of the object side surface of the second lens L2,

r5: the paraxial radius of curvature of the object side surface of the third lens L3,

r6: the paraxial curvature radius of the image side surface of the third lens L3,

r7: the paraxial radius of curvature of the object side surface of the fourth lens L4,

r8: The paraxial curvature radius of the image side surface of the fourth lens L4.

In addition, it is not necessary to satisfy all of the above-mentioned conditional expressions, and by satisfying each conditional expression individually, the effect corresponding to each conditional expression can be obtained.

In addition, in the present embodiment, the imaging lens satisfies the following Conditional Expressions (1a) to (26a), thereby exhibiting better effects.

(1a) 16＜νd4＜29

(2a) 0.6＜νd3/νd4＜1.7

(3a) 0.4＜|r2/r3|＜0.8

(4a) 1.0＜|f4|/f＜3.4

(5a) 0.25＜|r2|/f＜0.45

(6a) 0.3＜|r3|/f＜0.9

(7a) 0.9＜r6/|f3|＜4.9

(8a) 14＜(D3/|f3|)×100＜36

(9a) 0.15＜|f2|/f＜0.60

(10a) 0.2＜|f3|/f＜0.6

(11a) 16＜νd3＜29

(12a) 0.2<r1/f<0.3

(13a) 0.45＜r1/|r2|＜1.1

(14a) 0.25＜|r2/r8|＜1.50

(15a) 0.15＜|r2/f1|＜1.60

(16a) 1<|r3/r7|<3

(17a) 0.27＜|r5|/f＜0.65

(18a) 1.7＜|r5|/T3＜7.5

(19a) 0.10＜|r5|/r6＜1.35

(20a) 0.4＜|r5/f3|＜1.6

(21a) 0.3<r6/f<2.4

(22a) 0.2＜|r7|/f＜0.6

(23a) 0.4＜|r7|/(T3+bf)＜1.3

(24a) 0.2＜|r7/r8|＜1.3

(25a) 9＜(D2/|f2|)×100＜50

(26a) 0.1＜|f2/f4|＜0.6

Here, the symbols of each conditional expression are the same as those described in the previous paragraph. In addition, the lower limit value or the upper limit value of the corresponding conditional formula (1a) to the conditional formula (26a) may be applied to the lower limit value or the upper limit value of the conditional formula (1) to the conditional formula (26).

In the present embodiment, the aspherical shape adopted on the aspherical surface of the lens surface is Z, the height in the direction orthogonal to the optical axis is H, and the proximal radius of curvature is R, When the conic coefficient is k, and the aspheric coefficient is A4, A6, A8, A10, A12, A14, A16, A18, and A20, it is expressed by the formula 1.

[Mathematical formula 1]

Next, an example of the imaging lens according to the present embodiment is shown. In each embodiment, f represents the focal length of the entire system of the imaging lens, Fno represents the F value, ω represents the half-field pair, ih represents the maximum image height, and TTL represents the total optical length. Also, i represents the surface number from the object side, r represents the paraxial radius of curvature, d represents the distance between the lens surfaces on the optical axis (plane spacing), Nd represents the refractive index of the d-line (reference wavelength), and νd Indicates the dispersion coefficient relative to the d-line. In addition, the aspherical surface is indicated by adding a * (asterisk) symbol after the surface number i.

[Example 1]

Basic lens data are shown in Table 1 below.

[Table 1]

Example 1

unit mm

f=18.35

Fno=3.80

ω(°)=7.0

ih=2.29

TTL=17.24

face data

Composition lens data

Aspheric data

The imaging lens of Example 1 achieved an F value of 3.80. As shown in Table 7, Conditional Expressions (1) to (26) are satisfied.

FIG. 2 shows spherical aberration (mm), astigmatism (mm), and distortion (%) for the imaging lens of Example 1. FIG. The spherical aberration graph shows the amount of aberration at each wavelength with respect to the F line (486 nm), the d line (588 nm), and the C line (656 nm). In addition, the astigmatism diagrams show the aberration amount (solid line) of the d-line on the sagittal image plane S and the aberration amount (broken line) of the d-line on the meridional image plane T, respectively ( FIG. 4 , FIG. 6 , 8, 10 and 12 are the same). As shown in FIG. 2 , it can be seen that each aberration is satisfactorily corrected.

[Example 2]

Basic lens data are shown in Table 2 below.

[Table 2]

Example 2

unit mm

f=18.35

Fno=3.80

ω(°)=7.0

ih=2.29

TTL=18.16

face data

Composition lens data

Aspheric data

The imaging lens of Example 2 achieved an F value of 3.80. As shown in Table 7, Conditional Expressions (1) to (26) are satisfied.

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

[Example 3]

Basic lens data are shown in Table 3 below.

[table 3]

Example 3

unit mm

f=18.35

Fno=3.80

ω(°)=7.0

ih=2.29

TTL=18.02

face data

Composition lens data

Aspheric data

The imaging lens of Example 3 achieved an F value of 3.80. As shown in Table 7, Conditional Expressions (1) to (26) are satisfied.

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

[Example 4]

Basic lens data are shown in Table 4 below.

[Table 4]

Example 4

unit mm

f=18.35

Fno=3.80

ω(°)=7.0

ih=2.29

TTL=18.05

face data

Composition lens data

Aspheric data

The imaging lens of Example 4 achieved an F value of 3.80. As shown in Table 7, Conditional Expressions (1) to (26) are satisfied.

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

[Example 5]

Basic lens data are shown in Table 5 below.

[table 5]

Example 5

unit mm

f=18.35

Fno=3.80

ω(°)=7.0

ih=2.29

TTL=17.81

face data

Composition lens data

Aspheric data

The imaging lens of Example 5 achieved an F value of 3.80. As shown in Table 7, Conditional Expressions (1) to (26) are satisfied.

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

[Example 6]

Basic lens data are shown in Table 6 below.

[Table 6]

Example 6

unit mm

f=18.35

Fno=3.80

ω(°)=7.0

ih=2.29

TTL=18.07

face data

Composition lens data

Aspheric data

The imaging lens of the embodiment achieves an F-number of 3.80. As shown in Table 7, Conditional Expressions (1) to (26) are satisfied.

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

Table 7 shows the values of Conditional Expressions (1) to (26) related to Examples 1 to 6.

[Table 7]

Industrial Availability

When the imaging lens according to the present invention is applied to a product with a camera function, it is possible to contribute to lowering the F-number of the camera and to achieve higher performance of the camera.

Description of reference numerals

ST aperture diaphragm,

L1 first lens,

L2 second lens,

L3 third lens,

L4 fourth lens,

IR filter,

IMG camera surface.

Claims (7)

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

a first lens having a positive focal power;

a second lens;

a third lens; and

a fourth lens;

the first lens is convex towards the object side in a paraxial region; the concave surface of the third lens faces to the image side in the paraxial region; satisfies the following conditional expressions (1), (2), (3) and (4),

(1)13＜νd4＜34

(2)0.3＜νd3/νd4＜2.0

(3)0.25＜|r2/r3|＜0.85

(4)0.85＜|f4|/f＜3.85

wherein,

ν d 4: the dispersion coefficient of the fourth lens L4 with respect to the d-line,

ν d 3: the third lens L3 has an abbe number with respect to the d-line,

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

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

f 4: the focal length of the fourth lens is such that,

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 (5) is satisfied:

(5)0.15＜|r2|/f＜0.55

wherein,

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

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

3. The imaging lens according to claim 1, wherein the following conditional expression (6) is satisfied:

(6)0.2＜|r3|/f＜1.2

wherein,

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.

4. The imaging lens according to claim 1, wherein the following conditional expression (8) is satisfied:

(8)9＜(D3/|f3|)×100＜43

wherein,

d3: the thickness of the third lens on the optical axis,

f 3: the focal length of the third lens.

5. The imaging lens according to claim 1, characterized in that the following conditional expression (9) is satisfied:

(9)0.1＜|f2|/f＜0.7

wherein,

f 2: the focal length of the second lens is such that,

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

6. The imaging lens according to claim 1,

a first lens having a biconvex shape in a paraxial region;

a second lens having a negative focal power and having a biconcave shape in a paraxial region;

a third lens having a positive refractive power and having a meniscus shape with a concave surface facing the image side in the paraxial region; and

and a fourth lens having a negative refractive power and having a meniscus shape with a convex surface facing the image side in the paraxial region.

7. The imaging lens according to claim 1,

a first lens having a meniscus shape with a convex surface facing the object side in a paraxial region;

a second lens having a positive focal power and taking a biconvex shape in a paraxial region;

a third lens having negative refractive power and having a biconcave shape with a concave surface facing the image side in the paraxial region; and

and a fourth lens having a positive refractive power and having a meniscus shape with a concave surface facing the image side in the paraxial region.

Images