JP2024032572A - Imaging lens and imaging device - Google Patents

Abstract

To provide an image capturing lens which employs six-lens configuration to realize compactness, lightweight and low cost, and yet offers high optical performance by appropriately setting lens shapes.SOLUTION: An image capturing lens 10 disclosed herein comprises a first lens 110 having negative refractive power, a second lens 120 having negative refractive power, a third lens 130 having positive refractive power, an aperture stop 170, a fourth lens 140 having positive refractive power, a fifth lens 150 having negative refractive power, and a sixth lens 160 having positive refractive power, arranged in order from the object side, and satisfies the following conditional expressions: 1.4<fg/f<1.8 ...(1), 0.35<N5/f ...(2).SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an imaging lens and an imaging device.

Imaging lenses used in cameras, including surveillance cameras and vehicle-mounted cameras, are required to be resistant to environmental changes and have good imaging performance over the entire screen. In addition, the imaging lens is also required to be small and lightweight because the mounting space for mounting the imaging lens on the camera is often limited.

Technologies described in Patent Documents 1 and 2 have been proposed as single-focus imaging lenses that can meet the above requirements. For example, Patent Document 1 discloses a lens unit that can be used satisfactorily even in harsh environments with a wide required temperature range and has high chromatic aberration correction accuracy. For example, Patent Document 2 discloses a lens unit that can be used in a wide temperature range and wavelength band and is excellent in compactness.

JP2008-008960A Japanese Patent Application Publication No. 2013-047753

For example, in-vehicle cameras are now being used not only for conventional visual recognition purposes but also for sensing purposes to detect objects, and even higher performance is required. 2. Description of the Related Art As solid-state imaging devices such as CCDs (Charge Coupled Devices) and CMOSs (Complementary Metal-Oxide Semiconductor devices) increase in number of pixels, imaging lenses used in cameras are also required to have commensurately good optical performance.

The purpose of the present disclosure, which was made in view of the above-mentioned problems, is to provide an imaging lens and an imaging device that are small, lightweight, and inexpensive due to a six-element structure, and yet have high optical performance by appropriately setting the shape of the lens. Our goal is to provide the following.

An imaging lens according to an embodiment of the present disclosure includes:
(1)
An imaging lens,
In order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, an aperture stop, and a fourth lens having a positive refractive power. A lens, a fifth lens having negative refractive power, and a sixth lens having positive refractive power,
If the combined focal length of the fourth lens, the fifth lens, and the sixth lens for the d-line is fg, the focal length of the imaging lens for the d-line is f, and the refractive index of the fifth lens is N5, then the conditions formula,
1.4<fg/f<1.8 (1)
0.35<N5/f (2)
satisfy.

(2)
The imaging lens according to (1) above,
If the radius of curvature of the object side surface of the fourth lens is R8, and the radius of curvature of the image side surface of the fourth lens is R9, then the conditional expression
-0.4<(R8+R9)/(R8-R9)<0.25 (3)
may be satisfied.

(3)
The imaging lens described in (1) or (2) above,
If the focal length of the fourth lens with respect to the d-line is f4, then the conditional expression:
1.2<f4/f<1.8 (4)
may be satisfied.

(4)
The imaging lens according to any one of (1) to (3) above,
Each of both surfaces of the second lens may be a concave surface.

(5)
The imaging lens according to any one of (1) to (4) above,
If the axial thickness of the fourth lens is D8, then the conditional expression:
0.4<D8/f<0.7 (5)
may be satisfied.

(6)
The imaging lens according to any one of (1) to (5) above,
If the axial distance from the image side surface of the fifth lens to the object side surface of the sixth lens is D10, the conditional expression:
0.015<D10/f (6)
may be satisfied.

(7)
The imaging lens according to any one of (1) to (6) above,
conditional expression,
R8/f<1.9 (7)
may be satisfied.

(8)
The imaging lens according to any one of (1) to (7) above,
If the Abbe number of the second lens is ν2, then the conditional expression:
11<ν2/f (8)
may be satisfied.

(9)
The imaging lens according to any one of (1) to (8) above,
If the total length of the imaging lens on the axis is Da, then the conditional expression:
Da/f<5.2 (9)
may be satisfied.

(10)
The imaging lens according to any one of (1) to (9) above,
If the focal length of the fifth lens with respect to the d-line is f5, then the conditional expression:
-2.0<f5/f<-1.1 (10)
may be satisfied.

(11)
The imaging lens according to any one of (1) to (10) above,
If the focal length of the sixth lens with respect to the d-line is f6, then the conditional expression:
1.45<f6/f<1.8 (11)
may be satisfied.

(12)
The imaging lens according to any one of (1) to (11) above,
Each of both surfaces of the sixth lens may be an aspherical surface.

(13)
The imaging lens according to any one of (1) to (12) above,
The fourth lens and the fifth lens may be formed as a cemented lens.

(14)
The imaging lens according to any one of (1) to (13) above,
Each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens may be formed of a glass material.

(15)
The imaging lens according to any one of (1) to (14) above,
If the focal length of the first lens with respect to the d-line is f1, then the conditional expression:
-1.5<f1/f<-1.2 (12)
may be satisfied.

(16)
The imaging lens according to any one of (1) to (15) above,
If the focal length of the second lens with respect to the d-line is f2, then the conditional expression:
-3.8<f2/f<-2 (13)
may be satisfied.

(17)
The imaging lens according to any one of (1) to (16) above,
If the focal length of the third lens with respect to the d-line is f3, then the conditional expression:
1.6<f3/f<3.1 (14)
may be satisfied.

(18)
The imaging lens according to any one of (1) to (17) above,
If the half angle of view of the ray incident on the maximum image height position on the image plane is W, then the conditional expression is
48<W (15)
may be satisfied.

(19)
The imaging lens according to any one of (1) to (18) above,
The object side surface of the first lens may be a concave surface.

An imaging device according to an embodiment of the present disclosure includes:
(20)
In order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, an aperture stop, and a fourth lens having a positive refractive power. an imaging lens having a lens, a fifth lens having negative refractive power, and a sixth lens having positive refractive power;
an imaging element that converts an optical image formed through the imaging lens into an electrical signal;
Equipped with
If the combined focal length of the fourth lens, the fifth lens, and the sixth lens for the d-line is fg, the focal length of the imaging lens for the d-line is f, and the refractive index of the fifth lens is N5, then the conditions formula,
1.4<fg/f<1.8 (16)
0.35<N5/f (17)
satisfy.

According to an embodiment of the present disclosure, it is possible to provide an imaging lens and an imaging device that are small, lightweight, and inexpensive due to the six-lens configuration, and have high optical performance by appropriately setting the shape of the lens.

1 is a lens configuration diagram of an imaging lens according to Example 1 of the present disclosure. FIG. FIG. 2 is a graph diagram showing astigmatism of the imaging lens of FIG. 1. FIG. 2 is a graph diagram showing distortion aberration of the imaging lens of FIG. 1. FIG. FIG. 2 is a lens configuration diagram of an imaging lens according to Example 2 of the present disclosure. 4 is a graph diagram showing astigmatism of the imaging lens of FIG. 3. FIG. 4 is a graph diagram showing distortion aberration of the imaging lens of FIG. 3. FIG. FIG. 3 is a lens configuration diagram of an imaging lens according to Example 3 of the present disclosure. 6 is a graph diagram showing astigmatism of the imaging lens of FIG. 5. FIG. 6 is a graph diagram showing distortion aberration of the imaging lens of FIG. 5. FIG. FIG. 7 is a lens configuration diagram of an imaging lens according to Example 4 of the present disclosure. 8 is a graph diagram showing astigmatism of the imaging lens of FIG. 7. FIG. 8 is a graph diagram showing distortion aberration of the imaging lens of FIG. 7. FIG. FIG. 7 is a lens configuration diagram of an imaging lens according to Example 5 of the present disclosure. 10 is a graph diagram showing astigmatism of the imaging lens shown in FIG. 9. FIG. 10 is a graph diagram showing distortion aberration of the imaging lens of FIG. 9. FIG. FIG. 7 is a lens configuration diagram of an imaging lens according to Example 6 of the present disclosure. 12 is a graph diagram showing astigmatism of the imaging lens of FIG. 11. FIG. 12 is a graph diagram showing distortion aberration of the imaging lens of FIG. 11. FIG. FIG. 7 is a lens configuration diagram of an imaging lens according to Example 7 of the present disclosure. 14 is a graph diagram showing astigmatism of the imaging lens of FIG. 13. FIG. 14 is a graph diagram showing distortion aberration of the imaging lens of FIG. 13. FIG. FIG. 7 is a lens configuration diagram of an imaging lens according to Example 8 of the present disclosure. 16 is a graph diagram showing astigmatism of the imaging lens shown in FIG. 15. FIG. 16 is a graph diagram showing distortion aberration of the imaging lens shown in FIG. 15. FIG. FIG. 7 is a lens configuration diagram of an imaging lens according to Example 9 of the present disclosure. 18 is a graph diagram showing astigmatism of the imaging lens of FIG. 17. FIG. 18 is a graph diagram showing distortion aberration of the imaging lens of FIG. 17. FIG.

Hereinafter, an imaging lens 10 and an imaging device 1 according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. More specifically, the configurations and functions of the imaging lens 10 and the imaging device 1 that are common to each embodiment described below will be described. In the accompanying drawings showing the configurations of the imaging lens 10 and the imaging device 1, the "object side" corresponds to the left side, and the "image side" corresponds to the right side. The drawings used in the following explanation are schematic, and the dimensional ratios and the like on the drawings do not necessarily correspond to the actual ones.

The lens configuration of an imaging lens 10 and an imaging device 1 according to an embodiment will be mainly described with reference to FIG. 1, which will be described later, showing the configuration of an imaging lens 10 and an imaging device 1 of Example 1.

The imaging device 1 includes an imaging lens 10 and an imaging element 20 that converts an optical image formed through the imaging lens 10 into an electrical signal. The image sensor 20 includes, for example, a solid-state image sensor such as a CCD and a CMOS. An image plane 21 is formed on the surface of the image sensor 20. The imaging device 1 images a subject by causing the imaging lens 10 to form an image of the object on the image plane 21 of the image sensor 20 .

The imaging lens 10 includes a first lens 110, a second lens 120, a third lens 130, an aperture diaphragm 170, a fourth lens 140, a fifth lens 150, a sixth lens 160, and a first flat plate, which are arranged in order from the object side. 180a, and a second flat plate 180b. The fourth lens 140 and the fifth lens 150 are formed as a cemented lens. The imaging lens 10 is a single focus imaging lens composed of six lenses. Each of the first lens 110, second lens 120, third lens 130, fourth lens 140, fifth lens 150, and sixth lens 160 is made of a glass material.

The first lens 110 has a spherical shape. Each of both surfaces of the first lens 110 is a concave surface. The second lens 120 has a spherical shape. Each of both surfaces of the second lens 120 is a concave surface. The third lens 130 has a spherical shape. Each of both surfaces of the third lens 130 is a convex surface. The fourth lens 140 has a spherical shape. Each of both surfaces of the fourth lens 140 is a convex surface. The fifth lens 150 has a spherical shape. Each of both surfaces of the fifth lens 150 is a concave surface. Each of both surfaces of the sixth lens 160 is an aspherical surface. The first flat plate 180a includes an optical member such as an IR (Infrared) cut filter. The second flat plate 180b includes an optical member such as an LID glass arranged with respect to the image sensor 20. LID glass is a cover glass used for the image sensor 20 as an image sensor.

The imaging lens 10 is substantially composed of a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, and a sixth lens 160. In the present disclosure, "substantially constituted" means that the optical elements that substantially constitute the imaging lens 10 are six lenses, the first lens 110 to the sixth lens 160, but there are also other optical elements that substantially constitute the imaging lens 10. This means that the imaging lens 10 may include a lens having no optical power, as well as optical elements other than the lens including an aperture and a cover glass. For example, the imaging lens 10 includes, in addition to the first lens 110 to the sixth lens 160, an aperture stop 170, and a first flat plate 180a and a second flat plate 180b.

The imaging lens 10 includes, in order from the object side, a first lens 110 having a negative refractive power, a second lens 120 having a negative refractive power, a third lens 130 having a positive refractive power, and an aperture stop 170. , a fourth lens 140 having a positive refractive power, a fifth lens 150 having a negative refractive power, and a sixth lens 160 having a positive refractive power.

In the wide-angle imaging lens 10, it is necessary to shorten the focal length in order to obtain a wide angle of view, but due to mechanical constraints of the imaging lens 10, the back focus must be longer than the focal length. Therefore, a lens having a negative refractive power is arranged in front of the imaging lens 10, and the light incident on the imaging lens 10 from the object side is once diverged and then condensed by a lens having a positive refractive power at the rear. This makes it possible to make the principal point of the lens system protrude to the rear of the imaging lens 10 and ensure a long back focus compared to the focal length.

More specifically, the first lens 110 and second lens 120 having negative refractive power diverge the light, and the third lens 130, fourth lens 140, and sixth lens 160 each have positive refractive power converge the light. Shine. By arranging the first lens 110 and the second lens 120, which are negative lenses, closest to the object side in the imaging lens 10, it is possible to obtain sufficient negative refractive power to place the principal point at the rear. By arranging the third lens 130 having a positive refractive power in front of the aperture stop 170, it is possible to effectively correct lateral chromatic aberration. By arranging the fourth lens 140 and the sixth lens 160 having positive refractive power after the aperture stop 170, it is possible to reduce the angle of incidence of light onto the image plane 21 and to satisfactorily correct aberrations.

Aperture stop 170 is arranged between third lens 130 and fourth lens 140. If the aperture stop 170 were placed closer to the image side than the fourth lens 140, the imaging lens 10 would become larger, which is not preferable. In addition, if the aperture stop 170 were to be placed closer to the object side than the third lens 130, it would be difficult to widen the angle of the imaging lens 10, which is not preferable. Therefore, by arranging the aperture stop 170 between the third lens 130 and the fourth lens 140 described above, the imaging lens 10 can achieve good correction of various aberrations and compactness of the lens system.

The functions of the imaging lens 10 and the imaging device 1 according to one embodiment will be mainly described.

The imaging lens 10 satisfies the following conditional expressions (1) and (2).
1.4<fg/f<1.8 (1)
0.35<N5/f (2)
However, fg is the combined focal length of the fourth lens 140, the fifth lens 150, and the sixth lens 160 for the d-line. f is the focal length of the imaging lens 10 with respect to the d-line. N5 is the refractive index of the fifth lens 150.

Conditional expression (1) associates the composite focal length of the fourth lens 140 to the sixth lens 160 with the focal length of the imaging lens 10. When the value of fg/f exceeds the upper limit of 1.8, it becomes difficult for the fourth lens 140, fifth lens 150, and sixth lens 160 located on the image side of the aperture diaphragm 170 to collect light, resulting in astigmatism. Aberrations occur. When the value of fg/f becomes the lower limit of 1.4 or less, light is easily collected, but the refractive power of the lens group located on the image side of the aperture stop 170 is too large, so that the image plane 21 in the meridional direction is falls to the object side. By satisfying conditional expression (1), the occurrence of astigmatism and the inclination of the image plane 21 in the meridional direction toward the object side are suppressed.

Conditional expression (2) associates the refractive index of the fifth lens 150 with the focal length of the imaging lens 10. When the value of N5/f is larger than the lower limit value of 0.35, the refractive power of the fifth lens 150, which is a concave lens located behind the aperture stop 170, is ensured, and axial chromatic aberration can be corrected. Become.

The imaging lens 10 may further satisfy the following conditional expression (3).
-0.4<(R8+R9)/(R8-R9)<0.25 (3)
However, R8 is the radius of curvature of the object side surface of the fourth lens 140. R9 is the radius of curvature of the image side surface of the fourth lens 140.

Conditional expression (3) associates the radii of curvature of both surfaces of the fourth lens 140. When the value of (R8+R9)/(R8-R9) exceeds the upper limit value of 0.25, the difference in the radius of curvature between the front and back surfaces of the fourth lens 140, which is a convex lens arranged near the aperture stop 170, becomes large, causing an astigmatism. Large aberrations occur. By satisfying conditional expression (3), the occurrence of astigmatism is suppressed. Since the value of (R8+R9)/(R8-R9) is larger than the lower limit value of -0.4, it becomes possible to easily correct longitudinal chromatic aberration.

The imaging lens 10 may further satisfy the following conditional expression (4).
1.2<f4/f<1.8 (4)
However, f4 is the focal length of the fourth lens 140 with respect to the d-line.

Conditional expression (4) associates the focal length of the fourth lens 140 with the focal length of the imaging lens 10. When the value of f4/f exceeds the upper limit of 1.8, the refractive power of the fourth lens 140, which is a convex lens, becomes small, and the image plane 21 tilts toward the image side, making it difficult to correct field curvature. . When the value of f4/f is less than the lower limit of 1.2, the refractive power of the positive fourth lens 140 becomes too large, making it difficult to correct longitudinal chromatic aberration by the negative fifth lens 150. By satisfying conditional expression (4), it becomes easy to correct field curvature, and it also becomes easy to correct longitudinal chromatic aberration by the negative fifth lens 150.

Since both surfaces of the second lens 120 are concave, the imaging lens 10 can be brought into contact with the first lens 110 and the spacer on a flat surface without performing any additional processing on the second lens 120. A possible flat receiving part can be easily formed. This makes it possible to realize a configuration with low tolerance sensitivity. As shown in FIG. 1, the flat receiving portion is formed on the second lens 120 in the area farthest from the optical axis Ax and in the area where the first lens 110 and the second lens 120 are in contact with each other. has been done.

For example, if the lens surface is convex, it is necessary to additionally form a flat receiving portion in the area farthest from the optical axis on the outer periphery of the lens. If such a flat receiving portion does not exist in the convex lens, the receiving position of the convex lens relative to the concave lens will not be stable, and the optical axis of the convex lens may shift. As a result, assembly tolerances may not be met when a convex lens is assembled into a lens system. Since processing to additionally form a flat receiving part on the outer periphery of a convex lens surface is not easy, a concave lens surface having a flat receiving part as a result of normal processing is formed on the second lens 120. is desirable.

The imaging lens 10 may further satisfy the following conditional expression (5).
0.4<D8/f<0.7 (5)
However, D8 is the axial thickness of the fourth lens 140. That is, D8 is the distance from the object side surface of the fourth lens 140 to the image side surface of the fourth lens 140 on the optical axis Ax of the imaging lens 10 shown in FIG.

Conditional expression (5) associates the axial thickness of the fourth lens 140 with the focal length of the imaging lens 10. Since the value of D8/f is smaller than the upper limit value of 0.7, after the light ray passes through the fourth lens 140 as a convex lens arranged near the aperture stop 170, the light ray in the sagittal direction and the meridional direction is It is refracted appropriately and the occurrence of astigmatism is suppressed. When the value of D8/f becomes less than or equal to the lower limit of 0.4, the thickness of the fourth lens 140 becomes thinner, so that the image plane 21 in the meridional direction is curved. By satisfying conditional expression (5), curvature of the image plane 21 in the meridional direction is suppressed.

The imaging lens 10 may further satisfy the following conditional expression (6).
0.015<D10/f (6)
However, D10 is the axial distance from the image side surface of the fifth lens 150 to the object side surface of the sixth lens 160. That is, D10 is the distance from the image side surface of the fifth lens 150 to the object side surface of the sixth lens 160 on the optical axis Ax of the imaging lens 10 shown in FIG.

Conditional expression (6) associates the axial distance between the fifth lens 150 and the sixth lens 160 with the focal length of the imaging lens 10. When the value of D10/f is larger than the lower limit value of 0.015, the angle of incidence of the light beam incident on the image plane 21 is suppressed.

The imaging lens 10 may further satisfy the following conditional expression (7).
R8/f<1.9 (7)

Conditional expression (7) associates the radius of curvature of the object side surface of the fourth lens 140 with the focal length of the imaging lens 10. When the value of R8/f is smaller than the upper limit of 1.9, restrictions are placed on the convex surface of the fourth lens 140 located behind the aperture stop 170, making it possible to reduce the overall optical length. Therefore, the occurrence of astigmatism is suppressed.

The imaging lens 10 may further satisfy the following conditional expression (8).
11<ν2/f (8)
However, ν2 is the Abbe number of the second lens 120.

Conditional expression (8) associates the Abbe number of the second lens 120 with the focal length of the imaging lens 10. When the value of ν2/f is larger than the lower limit of 11, it becomes easy to correct chromatic aberration of magnification. In addition, inexpensive materials can be selected, making it easy to reduce the cost of the imaging lens 10.

The imaging lens 10 may further satisfy the following conditional expression (9).
Da/f<5.2 (9)
However, Da is the total length of the imaging lens 10 on the optical axis Ax. That is, Da is the distance from the object side surface of the first lens 110 to the image plane 21 on the optical axis Ax of the imaging lens 10 shown in FIG.

Conditional expression (9) associates the total length of the imaging lens 10 with the focal length of the imaging lens 10. When the value of Da/f is smaller than the upper limit of 5.2, the optical path ratio between the optical axis Ax and the position away from the optical axis Ax becomes high in each air lens. Point aberration is suppressed. In addition, the imaging lens 10 can be made smaller in the overall length direction and the radial direction, and the degree of freedom in designing the camera housing can be improved.

The imaging lens 10 may further satisfy the following conditional expression (10).
-2.0<f5/f<-1.1 (10)
However, f5 is the focal length of the fifth lens 150 with respect to the d-line.

Conditional expression (10) associates the focal length of the fifth lens 150 with the focal length of the imaging lens 10. When the value of f5/f exceeds the upper limit of -1.1, the refractive power of the fifth lens 150 increases, and the fifth lens 150, which is a concave lens on the image side of the aperture stop 170, causes chromatic aberration of magnification in the opposite direction. occurs to a large extent. When the value of f5/f becomes less than the lower limit of -2.0, the refractive power of the negative fifth lens 150 that cancels out the axial chromatic aberration generated by the positive fourth lens 140 becomes small, and the axial chromatic aberration decreases. Correction becomes difficult. By satisfying conditional expression (10), occurrence of lateral chromatic aberration in the opposite direction is suppressed, and longitudinal chromatic aberration can also be easily corrected.

The imaging lens 10 may further satisfy the following conditional expression (11).
1.45<f6/f<1.8 (11)
However, f6 is the focal length of the sixth lens 160 with respect to the d-line.

Conditional expression (11) associates the focal length of the sixth lens 160 with the focal length of the imaging lens 10. When the value of f6/f exceeds the upper limit of 1.8, the refractive power of the sixth lens 160, which is the convex lens closest to the image plane 21, decreases, causing the image plane 21 to fall toward the object side, resulting in field curvature. It becomes difficult to correct. By satisfying conditional expression (11), it becomes easy to correct field curvature. When the value of f6/f is larger than the lower limit of 1.45, the refractive power of the sixth lens 160 does not become too large, making it possible to lower the tolerance sensitivity. Thereby, the image plane 21 does not tilt toward the image side, and the curvature of field can be easily corrected.

In the imaging lens 10, each of both surfaces of the sixth lens 160 is aspherical, so that the sixth lens 160 closest to the image plane 21 has an aspherical shape, and the incident angle of light to the imaging element 20 can be easily adjusted. It is possible. As a result, spherical aberration and astigmatism can be easily corrected.

In the imaging lens 10, the fourth lens 140 and the fifth lens 150 are formed as a cemented lens, so that the fourth lens 140 and the fifth lens 150, which have high axis misalignment sensitivity, can be configured as a cemented lens, and the tolerance sensitivity can be reduced. It is possible to realize a low optical system. In addition, the number of lenses in the imaging lens 10 can be reduced by using a cemented lens, and the workload of assembling the imaging lens 10 into the imaging lens 10 can be reduced.

The imaging lens 10 has a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, and a sixth lens 160 each made of a glass material. It is possible to suppress yellowing and changes in optical properties due to temperature changes.

The imaging lens 10 may further satisfy the following conditional expression (12).
-1.5<f1/f<-1.2 (12)
However, f1 is the focal length of the first lens 110 with respect to the d-line.

Conditional expression (12) associates the focal length of the first lens 110 with the focal length of the imaging lens 10. If the value of f1/f exceeds the upper limit of −1.2, the refractive power of the first lens 110 as a concave lens in the imaging lens 10 becomes too large, resulting in a large curvature of field. By satisfying conditional expression (12), the occurrence of field curvature is suppressed. When the value of f1/f is larger than the lower limit value of −1.5, the refractive power of the first lens 110 does not become too small, so that longitudinal chromatic aberration can be favorably corrected.

The imaging lens 10 may further satisfy the following conditional expression (13).
-3.8<f2/f<-2 (13)
However, f2 is the focal length of the second lens 120 with respect to the d-line.

Conditional expression (13) associates the focal length of the second lens 120 with the focal length of the imaging lens 10. When the value of f2/f is smaller than the upper limit value of −2, the refractive power of the second lens 120 as a concave lens is appropriately suppressed, and astigmatism can be corrected well. When the value of f2/f becomes less than the lower limit of -3.8, the axial chromatic aberration generated in the second lens 120 becomes weaker, and as a result, it becomes difficult to correct the axial chromatic aberration in the entire imaging lens 10. By satisfying conditional expression (13), it becomes easy to correct longitudinal chromatic aberration in the entire imaging lens 10.

The imaging lens 10 may further satisfy the following conditional expression (14).
1.6<f3/f<3.1 (14)
However, f3 is the focal length of the third lens 130 with respect to the d-line.

Conditional expression (14) associates the focal length of the third lens 130 with the focal length of the imaging lens 10. When the value of f3/f exceeds the upper limit of 3.1, the refractive power of the third lens 130, which is a convex lens located before the aperture stop 170, becomes small, resulting in curvature of field. When the value of f3/f becomes the lower limit of 1.6 or less, the refractive power of the third lens 130, which is a convex lens in the imaging lens 10, becomes too large, and it is necessary to correct the longitudinal chromatic aberration that occurs in the convex lens. becomes difficult. By satisfying conditional expression (14), the occurrence of field curvature is suppressed, and it becomes easy to correct the longitudinal chromatic aberration occurring in the convex lens.

The imaging lens 10 may further satisfy conditional expression (15) below.
48<W (15)
However, W is the half angle of view of the light beam incident on the maximum image height position on the image plane 21.

Conditional expression (15) is an expression regarding the angle of view of the entire imaging lens 10 system. When the value of W becomes less than or equal to the lower limit of 48, it becomes difficult to secure an imaging range that should be satisfied by the imaging device 1 used for, for example, a vehicle-mounted camera. By satisfying conditional expression (15), the imaging range that should be satisfied by the imaging device 1 used for, for example, a vehicle-mounted camera can be easily secured.

In the imaging lens 10, since the object side surface of the first lens 110 is concave, it is possible to easily form a structure to be held by a retainer or the like without performing additional processing on the first lens 110. be. In addition, when the reflected light from the image plane 21 of the light incident on the imaging lens 10 is incident on the object side surface of the first lens 110, the re-reflected light tends to diverge without being condensed. Therefore, it is possible to suppress the occurrence of ghosts due to such re-reflected light being re-imaged on the image plane 21.

(Example)
Next, the lens configuration of an example of the imaging lens 10 of the present disclosure will be mainly described. More specifically, Examples 1 to 9 will be shown using specific numerical values of the imaging lens 10. Examples 1 to 9 have the features of the above-described embodiment with respect to the positive and negative refractive power of each lens, the surface shape, and the parameters shown in conditional expressions (1) to (15).

In Examples 1 to 9, the focal length f of the imaging lens 10 described above, the total length Da of the imaging lens 10 on the optical axis Ax, and each value of the F value and image height are as shown in Table 1 below. . In the various data for each example in Table 1, the values derived from the lens specifications, including the focal length f, etc., are also values for the d-line unless otherwise specified.

In Examples 1 to 9, the values of parameters included in each of conditional expressions (1) to (15) are as shown in Table 2 below.

In the basic lens data in each example, the number i (i is a natural number) in the lens specifications refers to all lenses included in the imaging lens 10, the aperture stop 170, and each surface of the first flat plate 180a and the second flat plate 180b. These are surface numbers assigned sequentially from the object side. Ri is the radius of curvature of the i-th surface. Di is the distance on the optical axis Ax between the i-th surface and the i+1-th surface. Nd is the refractive index for the d-line. νd is the Abbe number for the d-line.

In all the values of the following specifications, the unit of length such as the radius of curvature Ri and interplanar distance Di is expressed in millimeters (mm) unless otherwise specified, and the description in each table is omitted. However, since the imaging lens 10 can provide equivalent optical performance in proportional enlargement and proportional reduction, the present invention is not limited to this.

The shape of the aspherical surface of the lens described in the following examples is such that the direction from the object side to the image side is positive, k is a conical coefficient, A is a fourth-order aspherical coefficient, and B is a sixth-order aspherical coefficient. , C is an 8th-order aspherical coefficient, and D is a 10th-order aspherical coefficient. Here, h represents the height of the ray, c represents the reciprocal of the central radius of curvature, and Z represents the depth from the tangent plane to the surface vertex.

（１６）
以下の各実施例における非球面データは、基本レンズデータにおいて※を付したレンズ面の非球面形状を与える非球面係数などを示す。

(16)
The aspherical surface data in each of the following examples indicates the aspherical surface coefficient etc. that give the aspherical shape of the lens surface marked with * in the basic lens data.

(Example 1)
FIG. 1 is a lens configuration diagram of an imaging lens 10 according to Example 1 of the present disclosure. FIG. 1 shows the lens configuration of an imaging lens 10 according to Example 1 in an optical cross section.

As shown in FIG. 1, in the imaging lens 10 of Example 1, the first lens 110 is a biconcave lens having negative refractive power and a spherical shape. The second lens 120 is a biconcave lens with negative refractive power and a spherical shape. The third lens 130 is a biconvex lens with positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens with positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens with negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens with positive refractive power and an aspherical shape.

In FIG. 1, D1 corresponds to the axial thickness of the first lens 110, and is the distance between the surface S1 and the surface S2 on the optical axis Ax. D2 is the axial distance between surface S2 and surface S3. D3 corresponds to the axial thickness of the second lens 120, and is the distance between the surface S3 and the surface S4 on the optical axis Ax. D4 is the axial distance between surface S4 and surface S5. D5 corresponds to the axial thickness of the third lens 130, and is the distance between the surface S5 and the surface S6 on the optical axis Ax. D6 is the axial distance between surface S6 and surface S7. D7 is the axial distance between surface S7 and surface S8.

D8 corresponds to the axial thickness of the fourth lens 140, and is the distance between the surface S8 and the surface S9 on the optical axis Ax. D9 corresponds to the axial thickness of the fifth lens 150, and is the distance between the surface S9 and the surface S10 on the optical axis Ax. D10 is the axial distance between surface S10 and surface S11. D11 corresponds to the axial thickness of the sixth lens 160, and is the distance between the surface S11 and the surface S12 on the optical axis Ax. D12 is the axial distance between the surface S12 and the surface S13. D13 corresponds to the axial thickness of the first flat plate 180a, and is the distance between the surface S13 and the surface S14 on the optical axis Ax. D14 is the axial distance between the surface S14 and the surface S15. D15 corresponds to the axial thickness of the second flat plate 180b, and is the distance between the surface S15 and the surface S16 on the optical axis Ax. D16 is the axial distance between the surface S16 and the image plane 21.

The above explanation regarding the interplanar distance Di applies similarly to other embodiments below. The surface spacing Di is illustrated only in FIG. 1, and is omitted in other drawings.

※は非球面 Table 3 shows basic lens data including specification values of the imaging lens 10 according to the first embodiment. In Table 3, for the aspheric surfaces S11 and S12 indicated by *, the value of the radius of curvature Ri indicates the paraxial radius of curvature.

*Aspherical surface

Table 4 shows aspherical surface data including aspherical coefficients of the imaging lens 10 according to Example 1. The aspheric data shown in Table 4 is data for each of surfaces S11 and S12 of the sixth lens 160.

2A and 2B are aberration diagrams of the imaging lens 10 of FIG. 1.

FIG. 2A is a graph diagram showing astigmatism of the imaging lens 10 of FIG. 1. In FIG. 2A, the vertical axis shows the incident height on the entrance pupil with the pupil diameter normalized to 1, and the horizontal axis shows the shift in the imaging position. Each line in the graph indicates astigmatism (mm) for light of each wavelength shown on the right side of the graph. "S" means the value of the sagittal image plane, and "T" means the value of the tangential image plane.

FIG. 2B is a graph diagram showing distortion aberration of the imaging lens 10 of FIG. 1. In FIG. 2B, the vertical axis indicates the incident height on the entrance pupil with the pupil diameter normalized to 1, and the horizontal axis indicates the shift in the imaging position. Each line in the graph indicates the distortion (%) for light of each wavelength shown on the right side of the graph.

As shown in FIGS. 2A and 2B, according to Example 1, various aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

The above explanation regarding the aberration diagrams applies similarly to the aberration diagrams shown in each of the other examples, so the explanation will be omitted below.

(Example 2)
FIG. 3 is a lens configuration diagram of the imaging lens 10 according to Example 2 of the present disclosure. FIG. 3 shows the lens configuration of the imaging lens 10 according to the second embodiment in an optical cross section.

As shown in FIG. 3, in the imaging lens 10 of Example 2, the first lens 110 is a biconcave lens having negative refractive power and a spherical shape. The second lens 120 is a biconcave lens with negative refractive power and a spherical shape. The third lens 130 is a biconvex lens with positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens with positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens with negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens with positive refractive power and an aspherical shape.

※は非球面 Table 5 shows basic lens data including specification values of the imaging lens 10 according to the second embodiment. In Table 5, for the aspheric surfaces S11 and S12 indicated by *, the value of the radius of curvature Ri indicates the paraxial radius of curvature.

*Aspherical surface

Table 6 shows aspherical surface data including aspherical coefficients of the imaging lens 10 according to Example 2. The aspherical surface data shown in Table 6 is data for each of surfaces S11 and S12 of the sixth lens 160.

4A and 4B are aberration diagrams of the imaging lens 10 of FIG. 3. FIG. 4A is a graph diagram showing astigmatism of the imaging lens 10 of FIG. 3. FIG. FIG. 4B is a graph diagram showing distortion aberration of the imaging lens 10 of FIG. 3. FIG. As shown in FIGS. 4A and 4B, according to Example 2, various aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance can be obtained.

(Example 3)
FIG. 5 is a lens configuration diagram of the imaging lens 10 according to Example 3 of the present disclosure. FIG. 5 shows the lens configuration of the imaging lens 10 according to the third embodiment in an optical cross section.

As shown in FIG. 5, in the imaging lens 10 of Example 3, the first lens 110 is a biconcave lens having negative refractive power and a spherical shape. The second lens 120 is a biconcave lens with negative refractive power and a spherical shape. The third lens 130 is a biconvex lens with positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens with positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens with negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens with positive refractive power and an aspherical shape.

※は非球面 Table 7 shows basic lens data including specification values of the imaging lens 10 according to the third embodiment. In Table 7, for the aspheric surfaces S11 and S12 indicated by *, the value of the radius of curvature Ri indicates the paraxial radius of curvature.

*Aspherical surface

Table 8 shows aspherical surface data including aspherical coefficients of the imaging lens 10 according to Example 3. The aspherical surface data shown in Table 8 is data for each of surfaces S11 and S12 of the sixth lens 160.

6A and 6B are aberration diagrams of the imaging lens 10 of FIG. 5. FIG. 6A is a graph diagram showing astigmatism of the imaging lens 10 of FIG. 5. FIG. FIG. 6B is a graph diagram showing distortion aberration of the imaging lens 10 of FIG. 5. FIG. As shown in FIGS. 6A and 6B, according to Example 3, various aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

(Example 4)
FIG. 7 is a lens configuration diagram of the imaging lens 10 according to Example 4 of the present disclosure. FIG. 7 shows the lens configuration of the imaging lens 10 according to Example 4 in an optical cross section.

As shown in FIG. 7, in the imaging lens 10 of Example 4, the first lens 110 is a biconcave lens having negative refractive power and a spherical shape. The second lens 120 is a biconcave lens with negative refractive power and a spherical shape. The third lens 130 is a biconvex lens with positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens with positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens with negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens with positive refractive power and an aspherical shape.

※は非球面 Table 9 shows basic lens data including specification values of the imaging lens 10 according to Example 4. In Table 9, for the aspheric surfaces S11 and S12 indicated by *, the value of the radius of curvature Ri indicates the paraxial radius of curvature.

*Aspherical surface

Table 10 shows aspherical surface data including aspherical coefficients of the imaging lens 10 according to Example 4. The aspherical surface data shown in Table 10 is data for each of surfaces S11 and S12 of the sixth lens 160.

8A and 8B are aberration diagrams of the imaging lens 10 of FIG. 7. FIG. 8A is a graph diagram showing astigmatism of the imaging lens 10 of FIG. 7. FIG. 8B is a graph diagram showing distortion aberration of the imaging lens 10 of FIG. 7. As shown in FIGS. 8A and 8B, according to Example 4, various aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

(Example 5)
FIG. 9 is a lens configuration diagram of the imaging lens 10 according to Example 5 of the present disclosure. FIG. 9 shows the lens configuration of the imaging lens 10 according to the fifth embodiment in an optical cross section.

As shown in FIG. 9, in the imaging lens 10 of Example 5, the first lens 110 is a biconcave lens having negative refractive power and a spherical shape. The second lens 120 is a biconcave lens with negative refractive power and a spherical shape. The third lens 130 is a biconvex lens with positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens with positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens with negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens with positive refractive power and an aspherical shape.

※は非球面 Table 11 shows basic lens data including specification values of the imaging lens 10 according to Example 5. In Table 11, for the aspheric surfaces S11 and S12 indicated by *, the value of the radius of curvature Ri indicates the paraxial radius of curvature.

*Aspherical surface

Table 12 shows aspherical surface data including aspherical coefficients of the imaging lens 10 according to Example 5. The aspherical surface data shown in Table 12 is data for each of surfaces S11 and S12 of the sixth lens 160.

10A and 10B are aberration diagrams of the imaging lens 10 of FIG. 9. FIG. 10A is a graph diagram showing astigmatism of the imaging lens 10 of FIG. 9. FIG. FIG. 10B is a graph diagram showing distortion aberration of the imaging lens 10 of FIG. 9. As shown in FIGS. 10A and 10B, according to Example 5, various aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance can be obtained.

(Example 6)
FIG. 11 is a lens configuration diagram of the imaging lens 10 according to Example 6 of the present disclosure. FIG. 11 shows an optical cross section of the lens configuration of the imaging lens 10 according to the sixth embodiment.

As shown in FIG. 11, in the imaging lens 10 of Example 6, the first lens 110 is a biconcave lens having negative refractive power and a spherical shape. The second lens 120 is a biconcave lens with negative refractive power and a spherical shape. The third lens 130 is a biconvex lens with positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens with positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens with negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens with positive refractive power and an aspherical shape.

※は非球面 Table 13 shows basic lens data including specification values of the imaging lens 10 according to Example 6. In Table 13, for the aspheric surfaces S11 and S12 indicated by *, the value of the radius of curvature Ri indicates the paraxial radius of curvature.

*Aspherical surface

Table 14 shows aspherical surface data including aspherical coefficients of the imaging lens 10 according to Example 6. The aspherical surface data shown in Table 14 is data for each of surfaces S11 and S12 of the sixth lens 160.

12A and 12B are aberration diagrams of the imaging lens 10 of FIG. 11. FIG. 12A is a graph diagram showing astigmatism of the imaging lens 10 of FIG. 11. FIG. 12B is a graph diagram showing distortion aberration of the imaging lens 10 of FIG. 11. As shown in FIGS. 12A and 12B, according to Example 6, various aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance can be obtained.

(Example 7)
FIG. 13 is a lens configuration diagram of the imaging lens 10 according to Example 7 of the present disclosure. FIG. 13 shows the lens configuration of the imaging lens 10 according to Example 7 in an optical cross section.

As shown in FIG. 13, in the imaging lens 10 of Example 7, the first lens 110 is a biconcave lens having negative refractive power and a spherical shape. The second lens 120 is a biconcave lens with negative refractive power and a spherical shape. The third lens 130 is a biconvex lens with positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens with positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens with negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens with positive refractive power and an aspherical shape.

※は非球面 Table 15 shows basic lens data including specification values of the imaging lens 10 according to Example 7. In Table 15, for the aspheric surfaces S11 and S12 indicated by *, the value of the radius of curvature Ri indicates the paraxial radius of curvature.

*Aspherical surface

Table 16 shows aspherical surface data including aspherical coefficients of the imaging lens 10 according to Example 7. The aspherical surface data shown in Table 16 is data for each of surfaces S11 and S12 of the sixth lens 160.

14A and 14B are aberration diagrams of the imaging lens 10 of FIG. 13. FIG. 14A is a graph diagram showing astigmatism of the imaging lens 10 of FIG. 13. FIG. 14B is a graph diagram showing the distortion of the imaging lens 10 of FIG. 13. As shown in FIGS. 14A and 14B, according to Example 7, various aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

(Example 8)
FIG. 15 is a lens configuration diagram of the imaging lens 10 according to Example 8 of the present disclosure. FIG. 15 shows the lens configuration of the imaging lens 10 according to Example 8 in an optical cross section.

As shown in FIG. 15, in the imaging lens 10 of Example 8, the first lens 110 is a biconcave lens having negative refractive power and a spherical shape. The second lens 120 is a biconcave lens with negative refractive power and a spherical shape. The third lens 130 is a biconvex lens with positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens with positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens with negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens with positive refractive power and an aspherical shape.

※は非球面 Table 17 shows basic lens data including specification values of the imaging lens 10 according to Example 8. In Table 17, for the aspheric surfaces S11 and S12 indicated by *, the value of the radius of curvature Ri indicates the paraxial radius of curvature.

*Aspherical surface

Table 18 shows aspherical surface data including aspherical coefficients of the imaging lens 10 according to Example 8. The aspherical surface data shown in Table 18 is data for each of surfaces S11 and S12 of the sixth lens 160.

16A and 16B are aberration diagrams of the imaging lens 10 of FIG. 15. FIG. 16A is a graph diagram showing astigmatism of the imaging lens 10 of FIG. 15. FIG. 16B is a graph diagram showing distortion aberration of the imaging lens 10 of FIG. 15. As shown in FIGS. 16A and 16B, according to Example 8, various aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance can be obtained.

(Example 9)
FIG. 17 is a lens configuration diagram of the imaging lens 10 according to Example 9 of the present disclosure. FIG. 17 shows the lens configuration of the imaging lens 10 according to Example 9 in an optical cross section.

As shown in FIG. 17, in the imaging lens 10 of Example 9, the first lens 110 is a biconcave lens having negative refractive power and a spherical shape. The second lens 120 is a biconcave lens with negative refractive power and a spherical shape. The third lens 130 is a biconvex lens with positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens with positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens with negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens with positive refractive power and an aspherical shape.

※は非球面 Table 19 shows basic lens data including specification values of the imaging lens 10 according to Example 9. In Table 19, for the aspheric surfaces S11 and S12 indicated by *, the value of the radius of curvature Ri indicates the paraxial radius of curvature.

*Aspherical surface

Table 20 shows aspherical surface data including aspherical coefficients of the imaging lens 10 according to Example 9. The aspherical surface data shown in Table 20 is data for each of surfaces S11 and S12 of the sixth lens 160.

18A and 18B are aberration diagrams of the imaging lens 10 of FIG. 17. FIG. 18A is a graph diagram showing astigmatism of the imaging lens 10 of FIG. 17. FIG. 18B is a graph diagram showing the distortion of the imaging lens 10 of FIG. 17. As shown in FIGS. 18A and 18B, according to Example 9, various aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance can be obtained.

According to the above-described imaging lens 10 and imaging device 1 according to an embodiment of the present disclosure, the six-lens configuration is small, lightweight, and inexpensive, while high optical performance is achieved by appropriately setting the shape of the lens. It is possible. As a result, it is possible to realize an imaging lens 10 and an imaging device 1 that are compact and have high optical performance and can be mounted on cameras such as surveillance cameras and vehicle-mounted cameras.

By satisfying conditional expression (1), the imaging lens 10 can suppress the occurrence of astigmatism and the inclination of the image plane 21 in the meridional direction toward the object side. The imaging lens 10 can correct longitudinal chromatic aberration by satisfying conditional expression (2).

The imaging lens 10 can suppress the occurrence of astigmatism by satisfying conditional expression (3). In addition, the imaging lens 10 can easily correct axial chromatic aberration.

By satisfying conditional expression (4), the imaging lens 10 can easily correct field curvature, and can also easily correct axial chromatic aberration due to the negative fifth lens 150.

Since both surfaces of the second lens 120 are concave, the imaging lens 10 can be brought into contact with the first lens 110 and the spacer on a flat surface without performing any additional processing on the second lens 120. Possible flat receivers can be easily formed.

The imaging lens 10 can suppress the occurrence of astigmatism by satisfying conditional expression (5). In addition, the imaging lens 10 can suppress curvature of the image plane 21 in the meridional direction.

The imaging lens 10 can suppress the angle of incidence of the light beam incident on the image plane 21 by satisfying conditional expression (6).

The imaging lens 10 can suppress the occurrence of astigmatism by satisfying conditional expression (7).

The imaging lens 10 can easily correct chromatic aberration of magnification by satisfying conditional expression (8). In addition, the cost of the imaging lens 10 can be easily reduced by selecting inexpensive materials.

The imaging lens 10 can suppress astigmatism by satisfying conditional expression (9). In addition, the imaging lens 10 enables miniaturization in the overall length direction and radial direction, improving the degree of freedom in designing the camera housing.

By satisfying conditional expression (10), the imaging lens 10 can suppress the occurrence of lateral chromatic aberration in the opposite direction, and can also easily correct axial chromatic aberration.

The imaging lens 10 can easily correct field curvature by satisfying conditional expression (11). In addition, the imaging lens 10 can also have low tolerance sensitivity.

In the imaging lens 10, since both surfaces of the sixth lens 160 are aspherical, the angle of incidence of light onto the imaging element 20 can be easily adjusted. As a result, the imaging lens 10 can easily correct spherical aberration and astigmatism.

Since the fourth lens 140 and the fifth lens 150 are formed as a cemented lens, the imaging lens 10 can realize an optical system with low tolerance sensitivity. In addition, the imaging lens 10 can reduce the workload of assembling the imaging lens 10.

The imaging lens 10 has a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, and a sixth lens 160 each made of a glass material. It is possible to suppress yellowing and changes in optical properties due to temperature changes.

The imaging lens 10 can suppress the occurrence of field curvature by satisfying conditional expression (12). In addition, the imaging lens 10 can also satisfactorily correct axial chromatic aberration.

By satisfying conditional expression (13), the imaging lens 10 can easily correct longitudinal chromatic aberration in the entire imaging lens 10.

By satisfying conditional expression (14), the imaging lens 10 can suppress the occurrence of field curvature and easily correct the longitudinal chromatic aberration occurring in the third lens 130.

By satisfying conditional expression (15), the imaging lens 10 can easily secure an imaging range that should be satisfied by the imaging device 1 used for, for example, a vehicle-mounted camera.

In the imaging lens 10, since the object side surface of the first lens 110 is concave, it is possible to easily form a structure to be held by a retainer or the like without performing additional processing on the first lens 110. be. In addition, the imaging lens 10 can suppress the occurrence of ghosts.

It will be obvious to those skilled in the art that the present disclosure can be implemented in other predetermined forms than the embodiments described above without departing from the spirit or essential characteristics thereof. Accordingly, the above description is illustrative and not limiting. The scope of the disclosure is defined by the appended claims rather than by the foregoing description. Any changes that come within the range of equivalents are intended to be included therein.

For example, the shape, size, arrangement, orientation, number, etc. of each component described above are not limited to what is illustrated in the above description and drawings. The shape, size, arrangement, orientation, number, etc. of each component may be arbitrarily configured as long as the function can be realized.

Although the imaging lens 10 according to one embodiment has been described, the present disclosure is not limited to the imaging lens 10 of each example described above, and various modifications can be made without departing from the gist of the invention. For example, the specifications of the imaging lens 10 in each embodiment are merely examples, and various parameters can be changed within the scope of the present disclosure.

1 Imaging device 10 Imaging lens 110 First lens 120 Second lens 130 Third lens 140 Fourth lens 150 Fifth lens 160 Sixth lens 170 Aperture stop 180a First flat plate 180b Second flat plate 20 Imaging element 21 Image plane Ax Optical axis Di Surface spacing Da Total length Ri Radius of curvature Si Surface

Claims (20)

An imaging lens,
In order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, an aperture stop, and a fourth lens having a positive refractive power. A lens, a fifth lens having negative refractive power, and a sixth lens having positive refractive power,
If the combined focal length of the fourth lens, the fifth lens, and the sixth lens for the d-line is fg, the focal length of the imaging lens for the d-line is f, and the refractive index of the fifth lens is N5, then the conditions formula,
1.4<fg/f<1.8 (1)
0.35<N5/f (2)
An imaging lens that satisfies your needs. The imaging lens according to claim 1,
If the radius of curvature of the object side surface of the fourth lens is R8, and the radius of curvature of the image side surface of the fourth lens is R9, then the conditional expression
-0.4<(R8+R9)/(R8-R9)<0.25 (3)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
If the focal length of the fourth lens with respect to the d-line is f4, then the conditional expression:
1.2<f4/f<1.8 (4)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
Each of both surfaces of the second lens is a concave surface.
Imaging lens. The imaging lens according to claim 1 or 2,
If the axial thickness of the fourth lens is D8, then the conditional expression:
0.4<D8/f<0.7 (5)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
If the axial distance from the image side surface of the fifth lens to the object side surface of the sixth lens is D10, the conditional expression:
0.015<D10/f (6)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
conditional expression,
R8/f<1.9 (7)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
If the Abbe number of the second lens is ν2, then the conditional expression:
11<ν2/f (8)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
If the total length of the imaging lens on the axis is Da, then the conditional expression:
Da/f<5.2 (9)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
If the focal length of the fifth lens with respect to the d-line is f5, then the conditional expression:
-2.0<f5/f<-1.1 (10)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
If the focal length of the sixth lens with respect to the d-line is f6, then the conditional expression:
1.45<f6/f<1.8 (11)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
Each of both surfaces of the sixth lens is an aspherical surface.
Imaging lens. The imaging lens according to claim 1 or 2,
The fourth lens and the fifth lens are formed as a cemented lens,
Imaging lens. The imaging lens according to claim 1 or 2,
Each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens is formed of a glass material.
Imaging lens. The imaging lens according to claim 1 or 2,
If the focal length of the first lens with respect to the d-line is f1, then the conditional expression:
-1.5<f1/f<-1.2 (12)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
If the focal length of the second lens with respect to the d-line is f2, then the conditional expression:
-3.8<f2/f<-2 (13)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
If the focal length of the third lens with respect to the d-line is f3, then the conditional expression:
1.6<f3/f<3.1 (14)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
If the half angle of view of the ray incident on the maximum image height position on the image plane is W, then the conditional expression is
48<W (15)
An imaging lens that satisfies your needs. The imaging lens according to claim 1 or 2,
The object side surface of the first lens is a concave surface.
Imaging lens. In order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, an aperture stop, and a fourth lens having a positive refractive power. an imaging lens having a lens, a fifth lens having negative refractive power, and a sixth lens having positive refractive power;
an imaging element that converts an optical image formed through the imaging lens into an electrical signal;
Equipped with
If the combined focal length of the fourth lens, the fifth lens, and the sixth lens for the d-line is fg, the focal length of the imaging lens for the d-line is f, and the refractive index of the fifth lens is N5, then the conditions formula,
1.4<fg/f<1.8 (16)
0.35<N5/f (17)
An imaging device that satisfies the following.

Images