JP2024146584A - Imaging lens and imaging device - Google Patents

Abstract

An imaging lens with improved optical performance is provided.
[Solution] An imaging lens 10 according to an embodiment of the present disclosure includes, in order from the object side to the image side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, an aperture stop, a fourth lens having positive refractive power, a fifth lens having negative refractive power, a sixth lens having positive refractive power, and a seventh lens having positive refractive power. When the thickness on the optical axis of the second lens is D3, the radius of curvature of the image side surface of the first lens is R2, and the focal length of the imaging lens with respect to the d-line is f, the following formulas (1) and (2) are satisfied.
0.12<D3/f<0.14...(1)
-1.3<R2/f<-0.90...(2)
[Selected Figure] Figure 1

Description

This disclosure relates to imaging lenses and imaging devices.

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 across the entire screen. In addition, imaging lenses are required to be small and lightweight, due in part to the fact that the space available for mounting imaging lenses on cameras is often limited.

The 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 well even in harsh environments that require a wide 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 highly compact.

JP 2008-008960 A JP 2013-047753 A

Imaging lenses and imaging devices are required to have higher optical performance.

An imaging lens according to an embodiment of the present disclosure includes, in order from the object side to the image side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, an aperture stop, a fourth lens having positive refractive power, a fifth lens having negative refractive power, a sixth lens having positive refractive power, and a seventh lens having positive refractive power. When the thickness of the second lens on the optical axis is D3, the radius of curvature of the image side surface of the first lens is R2, and the focal length of the imaging lens with respect to the d-line is f, the following formulas (1) and (2) are satisfied.
0.12<D3/f<0.14...(1)
-1.3<R2/f<-0.90...(2)

An imaging device according to an embodiment of the present disclosure includes an imaging lens and an imaging element. The imaging lens is composed of, in order from the object side to the image side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, an aperture stop, a fourth lens having positive refractive power, a fifth lens having negative refractive power, a sixth lens having positive refractive power, and a seventh lens having positive refractive power. The imaging lens satisfies the following formulas (1) and (2), where D3 is the thickness on the optical axis of the second lens, R2 is the radius of curvature of the image side surface of the first lens, and f is the focal length of the imaging lens with respect to the d-line. The imaging element converts an optical image formed through the imaging lens into an electrical signal.
0.12<D3/f<0.14...(1)
-1.3<R2/f<-0.90...(2)

The imaging lens and imaging device according to one embodiment of the present disclosure can improve optical performance.

FIG. 1 is a lens configuration diagram of an imaging lens according to a first embodiment of the present disclosure. 2 is a graph showing astigmatism of the imaging lens of FIG. 1 . 2 is a graph showing distortion aberration of the imaging lens of FIG. 1. 2 is a graph showing spherical aberration of the imaging lens of FIG. 1 . FIG. 11 is a lens configuration diagram of an imaging lens according to a second embodiment of the present disclosure. FIG. 4 is a graph showing astigmatism of the imaging lens of FIG. 3 . 4 is a graph showing distortion aberration of the imaging lens of FIG. 3. FIG. 4 is a graph showing spherical aberration of the imaging lens of FIG. 3 . FIG. 11 is a lens configuration diagram of an imaging lens according to a third embodiment of the present disclosure. FIG. 6 is a graph showing astigmatism of the imaging lens of FIG. 5 . 6 is a graph showing distortion aberration of the imaging lens of FIG. 5 . FIG. 6 is a graph showing spherical aberration of the imaging lens of FIG. 5 . FIG. 11 is a lens configuration diagram of an imaging lens according to a fourth embodiment of the present disclosure. FIG. 8 is a graph showing astigmatism of the imaging lens of FIG. 7 . 8 is a graph showing distortion aberration of the imaging lens of FIG. 7. 8 is a graph showing spherical aberration of the imaging lens of FIG. 7. FIG. 13 is a lens configuration diagram of an imaging lens according to a fifth embodiment of the present disclosure. FIG. 10 is a graph showing astigmatism of the imaging lens of FIG. 9 . 10 is a graph showing distortion aberration of the imaging lens of FIG. 9 . 10 is a graph showing spherical aberration of the imaging lens of FIG. 9 . FIG. 13 is a lens configuration diagram of an imaging lens according to Example 6 of the present disclosure. 12 is a graph showing astigmatism of the imaging lens of FIG. 11. 12 is a graph showing distortion aberration of the imaging lens of FIG. 11. 12 is a graph showing spherical aberration of the imaging lens of FIG. 11. FIG. 13 is a lens configuration diagram of an imaging lens according to Example 7 of the present disclosure. FIG. 14 is a graph showing astigmatism of the imaging lens of FIG. 13. FIG. 14 is a graph showing distortion aberration of the imaging lens of FIG. 13 . FIG. 14 is a graph showing spherical aberration of the imaging lens of FIG. 13. FIG. 13 is a lens configuration diagram of an imaging lens according to an eighth embodiment of the present disclosure. FIG. 16 is a graph showing astigmatism of the imaging lens of FIG. 15 . 16 is a graph showing distortion aberration of the imaging lens of FIG. 15. FIG. 16 is a graph showing spherical aberration of the imaging lens of FIG. 15 . FIG. 13 is a lens configuration diagram of an imaging lens according to Example 9 of the present disclosure. FIG. 18 is a graph showing astigmatism of the imaging lens of FIG. 17. 18 is a graph showing distortion aberration of the imaging lens of FIG. 17. FIG. 18 is a graph showing spherical aberration of the imaging lens of FIG. 17.

Embodiments of the present disclosure are described below with reference to the drawings.

First Embodiment
Hereinafter, an imaging lens 10 and an imaging device 1 according to one embodiment will be described with appropriate reference to the drawings. In each of the attached 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. Each of the drawings used in the following description is schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones.

(Imaging device 1)
The imaging device 1 has an imaging lens 10 and an imaging element 20 that converts an optical image formed through the imaging lens 10 into an electrical signal. For example, the imaging element 20 includes a solid-state imaging element such as a charge coupled device (CCD) and a complementary metal oxide semiconductor (CMOS). The imaging element 20 has an image plane 21 located on its surface. The imaging device 1 images an object as a subject by forming an image of the object as the subject on the image plane 21 of the imaging element 20 by the imaging lens 10. For example, the imaging device 1 can be used for video shooting in which imaging is continuously and repeatedly performed. More specifically, for example, the imaging device 1 is used in a surveillance camera or an in-vehicle camera. When the imaging device 1 is used as an in-vehicle camera, for example, the imaging device 1 is located at least one of the side, front, and rear of a vehicle equipped with a control device that controls the imaging device 1. In other words, the imaging device 1 captures an image of at least one of the side, front, and rear of the vehicle.

(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, a sixth lens 160, and a seventh lens 170. In addition to the first lens 110 to the seventh lens 170, the imaging lens 10 may have other optical elements other than lenses, including a lens that has substantially no refractive power, an aperture, and a cover glass. For example, in addition to the first lens 110 to the seventh lens 170, the imaging lens 10 has an aperture aperture 180, a first flat plate 190a, and a second flat plate 190b.

The imaging lens 10 has, in order from the object side to the image side, a first lens 110, a second lens 120, a third lens 130, an aperture stop 180, a fourth lens 140, a fifth lens 150, a sixth lens 160, and a seventh lens 170. The imaging lens 10 is a single-focus imaging lens made up of seven lenses. The imaging lens 10 may have a first flat plate 190a and a second flat plate 190b located on the image side of the seventh lens 170.

The first lens 110 has a spherical shape. The object side surface and the image side surface of the first lens 110 are concave surfaces. The second lens 120 has a spherical shape. The object side surface and the image side surface of the second lens 120 are concave surfaces. The third lens 130 has a spherical shape. The object side surface and the image side surface of the third lens 130 are convex surfaces. The fourth lens 140 has a spherical shape. The object side surface and the image side surface of the fourth lens 140 are convex surfaces. The fifth lens 150 has a spherical shape. The object side surface of the fifth lens 150 is concave. The image side surface of the fifth lens 150 is convex. The sixth lens 160 has a spherical shape. Each of the two surfaces of the sixth lens 160 is convex. Each of the two surfaces of the seventh lens 170 is aspherical.

The first lens 110 has negative refractive power. The second lens 120 has negative refractive power. The third lens 130 has positive refractive power. The fourth lens 140 has positive refractive power. The fifth lens 150 has negative refractive power. The sixth lens 160 has positive refractive power. The seventh lens 170 has positive refractive power.

The imaging lens 10 used in a surveillance camera or an in-vehicle camera preferably has a short focal length to obtain a wide angle of view, but due to mechanical constraints of the imaging lens 10, the back focus needs to be longer than the focal length. Within the imaging lens 10, a lens with negative refractive power is located on the object side, and a lens with positive refractive power is located on the image side. Light incident on the imaging lens 10 from the object side is diverged by the lens with negative refractive power, and then focused by the lens with positive refractive power on the image side. This allows the principal point of the lens system to be projected behind the imaging lens 10, making it possible to ensure a back focus that is longer than the focal length.

Specifically, the first lens 110 and the second lens 120, which have negative refractive power, diverge light, and the third lens 130, the fourth lens 140, the sixth lens 160, and the seventh lens 170, which have positive refractive power, condense light. In the imaging lens 10, by arranging the first lens 110 and the second lens 120, which have negative refractive power, closest to the object side, the imaging lens 10 can secure sufficient negative refractive power to place the principal point rearward. In the imaging lens 10, by positioning the third lens 130, which has positive refractive power, on the object side of the aperture stop 180, the imaging lens 10 can perform good correction of chromatic aberration of magnification. In the imaging lens 10, by positioning the fourth lens 140, the sixth lens 160, and the seventh lens 170, which have positive refractive power, on the image side of the aperture stop 180, the imaging lens 10 can reduce the angle of incidence of light on the image plane 21 and can perform good correction of aberration.

The second lens 120 and the third lens 130 are formed as a cemented lens. The image side surface of the second lens 120 and the object side surface of the third lens 130 are in contact. For example, the second lens 120 and the third lens 130 may be cemented together with an adhesive. The fourth lens 140 and the fifth lens 150 are formed as a cemented lens. The image side surface of the fourth lens 140 and the object side surface of the fifth lens 150 are in contact. For example, the fourth lens 140 and the fifth lens 150 may be cemented together with an adhesive.

Each of the first lens 110 to the seventh lens 170 is formed of a glass material. This makes it possible to reduce yellowing due to ultraviolet rays and changes in optical properties due to temperature changes. Each of the first lens 110 to the seventh lens 170 may be made of a glass material having a different refractive index. The material of the first lens 110 to the seventh lens 170 is not limited to glass. For example, only one of the first lens 110 to the seventh lens 170 may be made of a material other than glass. For example, only one of the first lens 110 to the seventh lens 170 may be made of a resin material or the like.

The aperture stop 180 can adjust the F-number of the imaging lens 10. The aperture stop 180 is located between the third lens 130 and the fourth lens 140. For example, by arranging the aperture stop 180 between the third lens 130 and the fourth lens 140, it is possible to achieve good correction of, for example, astigmatism, distortion, or spherical aberration. For example, by arranging the aperture stop 180 between the third lens 130 and the fourth lens 140, it is possible to reduce the size of the lens system.

For example, the first flat plate 190a may be an optical filter that reduces the amount of light in a predetermined wavelength band that passes through. For example, the first flat plate 190a is composed of an optical member such as an infrared cut filter or an ultraviolet cut filter. When the first flat plate 190a is composed of an infrared cut filter, for example, the first flat plate 190a can reduce the influence of infrared rays on the image plane 21. When the first flat plate 190a is composed of an ultraviolet cut filter, for example, the first flat plate 190a can reduce the influence of ultraviolet rays on the image sensor 20. For example, the material of the infrared cut filter and the ultraviolet cut filter may be glass.

For example, the second flat plate 190b is composed of an optical member such as LID glass that is placed on the imaging element 20. The LID glass is a cover glass used for the imaging element 20 as an image sensor.

The functions of the imaging lens 10 and imaging device 1 are described below.

The imaging lens 10 satisfies the following conditional expressions (1) and (2).
0.12<D3/f<0.14...(1)
-1.3<R2/f<-0.90...(2)
D3 is the thickness on the optical axis Ax of the second lens 120. R2 is the radius of curvature of the image-side surface of the first lens 110. f is the focal length of the imaging lens 10 with respect to the d-line.

Conditional formula (1) relates the thickness D3 of the second lens 120 on the optical axis Ax to the focal length f of the imaging lens 10 with respect to the d-line. When the value of D3/f is greater than 0.12, the risk of the spherical aberration of the imaging lens 10 being overcorrected can be reduced. When the value of D3/f is less than 0.14, the risk of the spherical aberration of the imaging lens 10 being undercorrected can be reduced.

Conditional formula (2) relates the radius of curvature R2 on the image side of the first lens 110 to the focal length f of the imaging lens 10 with respect to the d-line. When the value of R2/f is greater than -1.3, the effect of spherical aberration at peripheral image heights can be reduced, and the risk of the spherical aberration of the imaging lens 10 being overcorrected can be reduced. When the value of R2/f is less than -0.90, the refractive power of the cemented lens of the fourth lens 140 and the fifth lens 150, which are arranged on the image side of the aperture stop 180, does not become too large, and the risk of the spherical aberration of the imaging lens 10 being undercorrected can be reduced.

The imaging lens 10 may satisfy the following conditional expression (3).
1.1<f4/f<1.3...(3)
f4 is the focal length of the fourth lens 140 with respect to the d-line.

Conditional expression (3) relates the focal length f4 of the fourth lens 140 for the d-line to the focal length f of the imaging lens 10 for the d-line. When the value of f4/f is greater than 1.1, the refractive power of the fourth lens 140, which is a convex lens located on the image side of the aperture stop 180, does not become too large, reducing the risk of the image surface in the radial (hereinafter, meridional) direction tilting toward the object side. When the value of f4/f is less than 1.3, the risk of the image surface in the concentric (hereinafter, sagittal) direction and the meridional direction tilting toward the image side can be reduced.

In the imaging lens 10, the object side surface of the fourth lens 140 may be convex. By making the object side surface of the fourth lens 140, which is placed on the image side of the aperture stop 180, a convex surface, it is possible to reduce the risk of ghosting occurring between the fourth lens 140 and the third lens 130, which is a negative lens located on the object side of the aperture stop 180.

In the imaging lens 10, the object side surface and the image side surface of the fourth lens 140 may be convex. The fourth lens 140 has a function of collecting light rays after passing through the aperture stop 180. By making both surfaces of the fourth lens 140, which collects light rays after passing through the aperture stop 180, convex, it becomes easier to correct aberrations in the imaging lens 10.

In the imaging lens 10, the image side surface of the fourth lens 140 and the object side surface of the fifth lens 150 may be in contact. The fourth lens 140 and the fifth lens 150 may be configured as a cemented lens. By positioning a lens in which the fourth lens 140, which has a large Abbe number, and the fifth lens 150, which has a small Abbe number, are cemented together on the image side of the aperture stop 180, it becomes easier to correct the axial chromatic aberration of the imaging lens 10. In addition, by making the lens located near the aperture stop 180 a cemented lens, the shape of the lens becomes easy to incorporate.

The imaging lens 10 may satisfy the following conditional expression (4).
0<D9/Da<0.035...(4)
Da is the overall length on the optical axis Ax of the imaging lens 10. D9 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.

Conditional formula (4) relates the total length Da on the optical axis Ax of the imaging lens 10 to the distance D8 on the optical axis Ax from the image-side surface of the fifth lens 150 to the object-side surface of the sixth lens 160. When the value of D9/Da is greater than 0, a gap is created between the image-side surface of the fifth lens 150 and the object-side surface of the sixth lens 160, and the refractive power of the entire imaging lens 10 does not become too small, reducing the risk of the image surface in the meridional direction tilting toward the object side. When D9/Da is less than 0.035, the refractive power of the entire imaging lens 10 does not become too large, reducing the risk of the image surface in the meridional direction tilting toward the image side.

The imaging lens 10 may satisfy the following conditional expression (5).
4.2<f23/f<5.7...(5)
f23 is the composite focal length of the second lens 120 and the third lens 130 with respect to the d-line.

Conditional expression (5) relates the composite focal length f23 of the second lens 120 and the third lens 130 for the d-line to the focal length f of the imaging lens 10 for the d-line. When the value of f23/f is greater than 4.2, the risk of the spherical aberration of the imaging lens 10 being undercorrected can be reduced. When f23/f is less than 5.7, the risk of the spherical aberration of the imaging lens 10 being overcorrected can be reduced.

The imaging lens 10 may satisfy the following conditional expression (6).
-1.20<f2/f<-1.05...(6)
f2 is the focal length of the second lens 120 with respect to the d-line.

Conditional formula (6) relates the focal length f2 of the second lens 120 for the d-line to the focal length f of the imaging lens 10 for the d-line. When the value of f2/f is greater than -1.20, the refractive power of the second lens 120, which has the function of collecting light incident from the first lens 110, does not become too small, reducing the risk of image separation in the sagittal and meridional directions. When f2/f is less than -1.05, the risk of insufficient correction of the spherical aberration of the imaging lens 10 can be reduced.

The imaging lens 10 may satisfy the following conditional expression (7).
0.25<D12/f<0.60...(7)
D12 is the thickness of the seventh lens 170 on the optical axis Ax.

Conditional formula (7) relates the thickness D12 of the seventh lens 170 on the optical axis Ax to the focal length f of the imaging lens 10 with respect to the d-line. When the value of D12/f is greater than 0.25, the refractive power of the seventh lens 170 does not become too large, and the balance of the refractive power in the sagittal direction and the meridional direction is less likely to be lost, making it easier to correct the astigmatism of the imaging lens 10. When the value of D12/f is less than 0.60, the risk of the image surface in the meridional direction falling toward the object side can be reduced.

The imaging lens 10 may satisfy the following conditional expression (8).
-1.25<f1/f<-1.10...(8)
f1 is the focal length of the first lens 110 with respect to the d-line.

Conditional formula (8) relates the focal length f1 of the first lens 110 with respect to the d-line to the focal length f of the imaging lens 10 with respect to the d-line. When the value of f1/f is greater than -1.25, the refractive power of the first lens 110, into which light first enters from the object side, does not become too small, reducing the risk of insufficient correction of the spherical aberration of the imaging lens 10. When the value of f1/f is less than -1.10, the radius of curvature R2 of the image-side surface of the first lens 110 does not become too small, making processing easier.

The imaging lens 10 may satisfy the following conditional expression (9).
2.2<f7/f<2.8...(9)
f7 is the focal length of the seventh lens 170 with respect to the d-line.

Conditional expression (9) relates the focal length f7 of the seventh lens 170 with respect to the d-line to the focal length f of the imaging lens 10 with respect to the d-line. When the value of f7/f is greater than 2.2, the refractive power of the seventh lens 170, which is the positive lens closest to the image surface 21, does not become too large, reducing the risk of insufficient correction of the spherical aberration of the imaging lens 10. When the value of f7/f is less than 2.8, the risk of the image surface in the meridional direction tilting toward the image side can be reduced.

The imaging lens 10 may satisfy the following conditional expression (10).
0.950<f3/f<1.05...(10)
f3 is the focal length of the third lens 130 with respect to the d-line.

Conditional formula (10) relates the focal length f3 of the third lens 130 with respect to the d-line to the focal length f of the imaging lens 10 with respect to the d-line. When the value of f3/f is greater than 0.95, the refractive power of the third lens 130 does not become too large, and the risk of significant axial chromatic aberration of the imaging lens 10 can be reduced. When the value of f3/f is less than 1.05, the risk of significant axial chromatic aberration of the imaging lens 10 can be reduced.

The imaging lens 10 may satisfy the following conditional expression (11).
-1.25<f5/f<-0.950...(11)
f5 is the focal length of the fifth lens 150 with respect to the d-line.

Conditional formula (11) relates the focal length f5 of the fifth lens 150 for the d-line to the focal length f of the imaging lens 10 for the d-line. When the value of f5/f is greater than -1.25, the refractive power of the fifth lens 150, which is the only negative lens among the lenses located on the object side of the aperture stop 180, does not become too small, reducing the risk that it will be difficult to correct the axial chromatic aberration of the imaging lens 10. When the value of f5/f is less than -0.950, the risk that the chromatic aberration on the optical axis Ax of the imaging lens 10 will be overcorrected can be reduced.

The imaging lens 10 may satisfy the following conditional expression (12).
2.05<f6/f<3.30...(12)
f6 is the focal length of the sixth lens 160 for the d-line.

Conditional expression (12) relates the focal length f6 of the sixth lens 160 with respect to the d-line to the focal length f of the imaging lens 10 with respect to the d-line. When the value of f6/f is greater than 2.05, the focal length f6 of the sixth lens 160 does not become too long, and the risk of undercorrection of the spherical aberration of the imaging lens 10 can be reduced. When the value of f6/f is less than 3.30, the risk of overcorrection of the spherical aberration around 80% of the image height can be reduced.

The imaging lens 10 may satisfy the following conditional expression (13).
4.5<Da/f<4.8...(13)

Conditional formula (13) relates the total length Da of the imaging lens 10 on the optical axis Ax to the focal length f of the imaging lens 10 with respect to the d-line. When the value of Da/f is greater than 4.5, the risk of separation of the images in the sagittal and meridional directions can be reduced. When the value of Da/f is less than 4.8, the spacing between the lenses in the imaging lens 10 can be kept constant, making it possible to correct the spherical aberration of the imaging lens 10. In addition, it is possible to reduce the overall length and radial size of the imaging lens 10, improving the degree of freedom in designing the camera housing.

In the imaging lens 10, the object side surface and the image side surface of the seventh lens 170 may be aspheric. By making the lens closest to the imaging surface aspheric, it becomes possible to easily adjust the angle of incidence on the sensor, making it easier to correct spherical aberration and astigmatism.

The total length Da of the imaging lens 10 on the optical axis Ax is the distance from the object side surface of the first lens 110 to the position where parallel light converges to one point when the parallel light is incident from the object side toward the imaging lens 10. The total length Da of the imaging lens 10 on the optical axis Ax corresponds to the distance from the object side surface of the first lens 110 to the image plane 21.

Next, the lens configuration of the examples of the imaging lens 10 of the present disclosure will be mainly described. More specifically, Examples 1 to 9 are shown using specific numerical values of the imaging lens 10. Examples 1 to 9 have the above-mentioned characteristics of the imaging lens 10 with respect to the positive and negative refractive powers of each lens, the surface shapes, and the parameters shown in conditional expressions (1) to (13).

In Examples 1 to 9, the focal length f of the imaging lens 10, the F-number on the optical axis Ax of the imaging lens 10, and the total length Da are as shown in Table 1. In the data in each Example in Table 1, the values derived from the lens specifications, including the focal length f, are values for the d-line unless otherwise specified.

In Examples 1 to 9, the parameter values included in each of conditional expressions (1) to (13) are as shown in Table 2 below.

In the basic lens data in each embodiment, the number i (i is a natural number) in the lens specifications is a surface number given to each surface of all lenses, aperture stop 180, first plate 190a, and second plate 190b included in the imaging lens 10, in order from the object side. Si indicates the i-th surface. 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 Si and the i+1-th surface Si+1. Nd is the refractive index for the d-line. νd is the Abbe number for the d-line. The surface spacing Di is shown only in FIG. 1 in embodiment 1, and is omitted in the drawings in other embodiments.

For all the values of the following specifications, the units of length such as the radius of curvature Ri and the surface spacing Di are in millimeters (mm) unless otherwise specified, and are omitted in each table. In each table, "E" indicates exponential notation (powers of 10). The configuration of the imaging lens 10 is not limited to the configuration in the following examples, and the same optical performance can be obtained in both proportional magnification and proportional reduction.

The aspheric shape of each lens surface in the following examples is expressed by the following formula (16). Formula (16) is the aspheric equation.

The numerical values in formula (16) are positive in the direction from the object side to the image side. k is the conical coefficient, A is the fourth-order aspheric coefficient, B is the sixth-order aspheric coefficient, C is the eighth-order aspheric coefficient, and D is the tenth-order aspheric coefficient. h is the height of the light ray, c is the inverse of the central radius of curvature, and Z is the depth from the tangent plane to the surface vertex. The aspheric data in each of the following examples indicates the aspheric coefficients, etc., when the aspheric shape of the lens surfaces marked with "*" in the basic lens data is expressed using formula 16.

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 an optical cross section of the lens configuration of the imaging lens 10 according to Example 1. As shown in Fig. 1, in the imaging lens 10 of Example 1, the refractive powers and shapes of the first lens 110 to the seventh lens 170 are as described above.

In FIG. 1, D1 corresponds to the thickness of the first lens 110 on the optical axis Ax. D3 corresponds to the thickness of the second lens 120 on the optical axis Ax. D4 corresponds to the thickness of the third lens 130 on the optical axis Ax. D7 corresponds to the thickness of the fourth lens 140 on the optical axis Ax. D8 corresponds to the thickness of the fifth lens 150 on the optical axis Ax. D10 corresponds to the thickness of the sixth lens 160 on the optical axis Ax. D12 corresponds to the thickness of the seventh lens 170 on the optical axis Ax. D14 corresponds to the thickness of the first plate 190a on the optical axis Ax. D16 corresponds to the thickness of the second plate 190b on the optical axis Ax. The above description of the surface spacing Di applies to the other examples below.

Table 3 shows basic lens data including the specifications of the imaging lens 10 according to Example 1. In Table 3, for the aspheric surfaces S12 and S13 indicated with "*", the value of the radius of curvature Ri indicates the paraxial radius of curvature.

Table 4 shows aspheric data including aspheric coefficients of the imaging lens 10 according to Example 1. The aspheric data shown in Table 4 is data for each of the surfaces S12 and S13 of the seventh lens 170.

Figures 2A, 2B, and 2C are graphs showing the various aberrations of the imaging lens 10 in Figure 1.

Figure 2A is a graph showing the astigmatism of the imaging lens 10 of Figure 1. In Figure 2A, the vertical axis shows the entrance height on the entrance pupil normalized to a pupil diameter of 1, and the horizontal axis shows the deviation of the imaging position. Each line in the graph shows the astigmatism (mm) for light of each wavelength shown on the right of the graph. "Sagittal" means the value of the image plane in the sagittal direction, and "Tangential" means the value of the image plane in the vertical (hereinafter, tangential) direction.

Figure 2B is a graph showing the distortion of the imaging lens 10 of Figure 1. In Figure 2B, the vertical axis shows the entrance height on the entrance pupil normalized to a pupil diameter of 1, and the horizontal axis shows the deviation of the imaging position. Each line in the graph shows the distortion (%) for each wavelength of light shown on the right of the graph.

Figure 2C is a graph showing the spherical aberration of the imaging lens 10 of Figure 1. In Figure 2C, the vertical axis shows the entrance height on the entrance pupil normalized to a pupil diameter of 1, and the horizontal axis shows the deviation of the imaging position. Each line in the graph shows the spherical aberration (mm) for light of each wavelength shown on the right of the graph.

As shown in Figures 2A, 2B, and 2C, according to Example 1, astigmatism, distortion, and spherical aberration are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

The above explanation of the aberration diagrams also applies to the aberration diagrams shown in the other examples, so we will omit the explanation 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 an optical cross section of the lens configuration of the imaging lens 10 according to Example 2. As shown in Fig. 3, in the imaging lens 10 of Example 2, the refractive powers and shapes of the first lens 110 to the seventh lens 170 are as described above.

Table 5 shows basic lens data including the specifications of the imaging lens 10 according to Example 2. In Table 5, for the aspheric surfaces S12 and S13 indicated with "*", the value of the radius of curvature Ri indicates the paraxial radius of curvature.

Table 6 shows aspheric data including aspheric coefficients of the imaging lens 10 according to Example 2. The aspheric data shown in Table 6 is data for each of the surfaces S12 and S13 of the seventh lens 170.

Figures 4A, 4B, and 4C are aberration diagrams of the imaging lens 10 of Figure 3. Figure 4A is a graph showing the astigmatism of the imaging lens 10 of Figure 3. Figure 4B is a graph showing the distortion aberration of the imaging lens 10 of Figure 3. Figure 4C is a graph showing the spherical aberration of the imaging lens 10 of Figure 3. As shown in Figures 4A, 4B, and 4C, according to Example 2, astigmatism, distortion, and spherical aberration are well corrected, and an imaging lens 10 with excellent imaging performance is 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 an optical cross section of the lens configuration of the imaging lens 10 according to Example 3. As shown in Fig. 5, in the imaging lens 10 of Example 3, the refractive powers and shapes of the first lens 110 to the seventh lens 170 are as described above.

Table 7 shows basic lens data including the specifications of the imaging lens 10 according to Example 3. In Table 7, for the aspheric surfaces S12 and S13 indicated with "*", the value of the radius of curvature Ri indicates the paraxial radius of curvature.

Table 8 shows aspheric data including aspheric coefficients of the imaging lens 10 according to Example 3. The aspheric data shown in Table 8 is data for each of the surfaces S12 and S13 of the seventh lens 170.

Figures 6A, 6B, and 6C are aberration diagrams of the imaging lens 10 of Figure 5. Figure 6A is a graph showing the astigmatism of the imaging lens 10 of Figure 5. Figure 6B is a graph showing the distortion aberration of the imaging lens 10 of Figure 5. Figure 6C is a graph showing the spherical aberration of the imaging lens 10 of Figure 5. As shown in Figures 6A, 6B, and 6C, according to Example 3, astigmatism, distortion, and spherical aberration 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 an optical cross section of the lens configuration of the imaging lens 10 according to Example 4. As shown in Fig. 7, in the imaging lens 10 of Example 4, the refractive powers and shapes of the first lens 110 to the seventh lens 170 are as described above.

Table 9 shows basic lens data including the specifications of the imaging lens 10 according to Example 4. In Table 9, for the aspheric surfaces S12 and S13 indicated with "*", the value of the radius of curvature Ri indicates the paraxial radius of curvature.

Table 10 shows aspheric data including aspheric coefficients of the imaging lens 10 according to Example 4. The aspheric data shown in Table 10 is data for each of the surfaces S12 and S13 of the seventh lens 170.

Figures 8A, 8B, and 8C are aberration diagrams of the imaging lens 10 of Figure 7. Figure 8A is a graph showing the astigmatism of the imaging lens 10 of Figure 7. Figure 8B is a graph showing the distortion aberration of the imaging lens 10 of Figure 7. Figure 8C is a graph showing the spherical aberration of the imaging lens 10 of Figure 7. As shown in Figures 8A, 8B, and 8C, according to Example 4, astigmatism, distortion, and spherical aberration are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

Example 5
Fig. 9 is a lens configuration diagram of an imaging lens 10 according to Example 5 of the present disclosure. Fig. 9 illustrates an optical cross section of the lens configuration of the imaging lens 10 according to Example 5. As shown in Fig. 9, in the imaging lens 10 of Example 5, the refractive powers and shapes of the first lens 110 to the seventh lens 170 are as described above.

Table 11 shows basic lens data including the specifications of the imaging lens 10 according to Example 5. In Table 11, for the aspheric surfaces S12 and S13 indicated with "*", the value of the radius of curvature Ri indicates the paraxial radius of curvature.

Table 12 shows aspheric data including aspheric coefficients of the imaging lens 10 according to Example 5. The aspheric data shown in Table 12 is data for each of the surfaces S12 and S13 of the seventh lens 170.

Figures 10A, 10B, and 10C are aberration diagrams of the imaging lens 10 of Figure 9. Figure 10A is a graph showing the astigmatism of the imaging lens 10 of Figure 9. Figure 10B is a graph showing the distortion aberration of the imaging lens 10 of Figure 9. Figure 10C is a graph showing the spherical aberration of the imaging lens 10 of Figure 9. As shown in Figures 10A, 10B, and 10C, according to Example 5, astigmatism, distortion, and spherical aberration are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

(Example 6)
Fig. 11 is a lens configuration diagram of an imaging lens 10 according to Example 6 of the present disclosure. Fig. 11 is an optical cross-sectional view showing the lens configuration of the imaging lens 10 according to Example 6. As shown in Fig. 11, in the imaging lens 10 of Example 6, the refractive powers and shapes of the first lens 110 to the seventh lens 170 are as described above.

Table 13 shows basic lens data including the specifications of the imaging lens 10 according to Example 6. In Table 13, for the aspheric surfaces S12 and S13 indicated with "*", the value of the radius of curvature Ri indicates the paraxial radius of curvature.

Table 14 shows aspheric data including aspheric coefficients of the imaging lens 10 according to Example 6. The aspheric data shown in Table 14 is data for each of the surfaces S12 and S13 of the seventh lens 170.

12A, 12B, and 12C are aberration diagrams of the imaging lens 10 of FIG. 11. FIG. 12A is a graph showing the astigmatism of the imaging lens 10 of FIG. 11. FIG. 12B is a graph showing the distortion aberration of the imaging lens 10 of FIG. 11. FIG. 12C is a graph showing the spherical aberration of the imaging lens 10 of FIG. 11. As shown in FIG. 12A, 12B, and 12C, according to Example 6, astigmatism, distortion, and spherical aberration are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

(Example 7)
Fig. 13 is a lens configuration diagram of an imaging lens 10 according to Example 7 of the present disclosure. Fig. 13 is an optical cross-sectional view showing the lens configuration of the imaging lens 10 according to Example 7. As shown in Fig. 13, in the imaging lens 10 of Example 7, the refractive powers and shapes of the first lens 110 to the seventh lens 170 are as described above.

Table 15 shows basic lens data including the specifications of the imaging lens 10 according to Example 7. In Table 15, for the aspheric surfaces S12 and S13 indicated with "*", the value of the radius of curvature Ri indicates the paraxial radius of curvature.

Table 16 shows aspheric data including aspheric coefficients of the imaging lens 10 according to Example 7. The aspheric data shown in Table 16 is data for each of the surfaces S12 and S13 of the seventh lens 170.

Figures 14A, 14B, and 14C are aberration diagrams of the imaging lens 10 of Figure 13. Figure 14A is a graph showing the astigmatism of the imaging lens 10 of Figure 13. Figure 14B is a graph showing the distortion aberration of the imaging lens 10 of Figure 13. Figure 14C is a graph showing the spherical aberration of the imaging lens 10 of Figure 13. As shown in Figures 14A, 14B, and 14C, according to Example 7, astigmatism, distortion, and spherical aberration are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

(Example 8)
Fig. 15 is a lens configuration diagram of an imaging lens 10 according to Example 8 of the present disclosure. Fig. 15 is an optical cross-sectional view showing the lens configuration of the imaging lens 10 according to Example 8. As shown in Fig. 15, in the imaging lens 10 of Example 8, the refractive powers and shapes of the first lens 110 to the seventh lens 170 are as described above.

Table 17 shows basic lens data including the specifications of the imaging lens 10 according to Example 8. In Table 17, for the aspheric surfaces S12 and S13 indicated with "*", the value of the radius of curvature Ri indicates the paraxial radius of curvature.

Table 18 shows aspheric data including aspheric coefficients of the imaging lens 10 according to Example 8. The aspheric data shown in Table 18 is data for each of the surfaces S12 and S13 of the seventh lens 170.

Figures 16A, 16B, and 16C are aberration diagrams of the imaging lens 10 of Figure 15. Figure 16A is a graph showing the astigmatism of the imaging lens 10 of Figure 15. Figure 16B is a graph showing the distortion aberration of the imaging lens 10 of Figure 15. Figure 16C is a graph showing the spherical aberration of the imaging lens 10 of Figure 15. As shown in Figures 16A, 16B, and 16C, according to Example 8, astigmatism, distortion, and spherical aberration are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

(Example 9)
Fig. 17 is a lens configuration diagram of an imaging lens 10 according to Example 9 of the present disclosure. Fig. 17 illustrates an optical cross section of the lens configuration of the imaging lens 10 according to Example 9. As shown in Fig. 17, in the imaging lens 10 of Example 9, the refractive powers and shapes of the first lens 110 to the seventh lens 170 are as described above.

Table 19 shows basic lens data including the specifications of the imaging lens 10 according to Example 9. In Table 19, for the aspheric surfaces S12 and S13 indicated with "*", the value of the radius of curvature Ri indicates the paraxial radius of curvature.

Table 20 shows aspheric data including aspheric coefficients of the imaging lens 10 according to Example 9. The aspheric data shown in Table 20 is data for each of the surfaces S12 and S13 of the seventh lens 170.

Figures 18A, 18B, and 18C are aberration diagrams of the imaging lens 10 of Figure 17. Figure 18A is a graph showing the astigmatism of the imaging lens 10 of Figure 17. Figure 18B is a graph showing the distortion aberration of the imaging lens 10 of Figure 17. Figure 18C is a graph showing the spherical aberration of the imaging lens 10 of Figure 17. As shown in Figures 18A, 18B, and 18C, according to Example 9, astigmatism, distortion, and spherical aberration are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

According to the imaging lens 10 and imaging device 1 according to the embodiment of the present disclosure described above, high optical performance can be achieved with a seven-lens configuration. As a result, it is possible to realize an imaging lens 10 and imaging device 1 with high optical performance that can be mounted on cameras including surveillance cameras and vehicle-mounted cameras.

It is obvious to those skilled in the art that the present disclosure can be realized in other specific forms than the above-described embodiments without departing from the spirit or essential characteristics thereof. Therefore, the above description is illustrative and not limiting. The scope of the disclosure is defined by the appended claims, not by the above description. Any modifications that are within the scope of the equivalents of all modifications are intended to be included therein.

For example, the shape, size, arrangement, orientation, and number of each of the above-mentioned components are not limited to the above description and the illustrations in the drawings. The shape, size, arrangement, orientation, and number of each of the components may be configured arbitrarily as long as the function can be realized.

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

REFERENCE SIGNS LIST 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 seventh lens 180 aperture stop 190a first flat plate 190b second flat plate 20 imaging element 21 image surface Ax optical axis Di surface separation Da total length Ri radius of curvature Si surface

Claims (18)

An imaging lens,
The optical system comprises, in order from the object side to the image side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, an aperture stop, a fourth lens having positive refractive power, a fifth lens having negative refractive power, a sixth lens having positive refractive power, and a seventh lens having positive refractive power,
an imaging lens that satisfies the following expressions (1) and (2), where D3 is a thickness on the optical axis of the second lens, R2 is a radius of curvature of the image-side surface of the first lens, and f is a focal length of the imaging lens with respect to a d-line:
0.12<D3/f<0.14...(1)
-1.3<R2/f<-0.90...(2) The imaging lens according to claim 1 ,
An imaging lens that satisfies the following conditional expression (3), where the focal length of the fourth lens with respect to the d-line is f4.
1.1<f4/f<1.3...(3) The imaging lens according to claim 1 ,
an object-side surface of the fourth lens having a convex shape; The imaging lens according to claim 3 ,
the object-side surface and the image-side surface of the fourth lens have a convex shape. The imaging lens according to claim 1 ,
an image pickup lens, wherein the image side surface of the fourth lens and the object side surface of the fifth lens are in contact with each other. The imaging lens according to claim 1 ,
An imaging lens that satisfies the following conditional expression (4), where Da is a total length of the imaging lens on the optical axis, and D9 is a distance on the optical axis from the image-side surface of the fifth lens to the object-side surface of the sixth lens:
0<D9/Da<0.035...(4) The imaging lens according to claim 1 ,
An imaging lens that satisfies the following conditional expression (5), where a composite focal length of the second lens and the third lens with respect to the d-line is f23.
4.2<f23/f<5.7...(5) The imaging lens according to claim 1 ,
An imaging lens that satisfies the following conditional expression (6), where the focal length of the second lens with respect to the d-line is f2:
-1.20<f2/f<-1.05...(6) The imaging lens according to claim 1 ,
An imaging lens that satisfies the following conditional expression (7), where D12 is the thickness of the seventh lens on the optical axis:
0.25<D12/f<0.60 (7) The imaging lens according to claim 1 ,
An imaging lens that satisfies the following conditional expression (8), where the focal length of the first lens with respect to the d-line is f1:
-1.25<f1/f<-1.10...(8) The imaging lens according to claim 1 ,
An imaging lens that satisfies the following conditional expression (9), where the focal length of the seventh lens with respect to the d-line is f7.
2.2<f7/f<2.8...(9) The imaging lens according to claim 1 ,
An imaging lens that satisfies the following conditional expression (10), where the focal length of the third lens with respect to the d-line is f3.
0.950<f3/f<1.05...(10) The imaging lens according to claim 1 ,
An imaging lens that satisfies the following conditional expression (11), where the focal length of the fifth lens with respect to the d-line is f5.
-1.25<f5/f<-0.950...(11) The imaging lens according to claim 1 ,
An imaging lens that satisfies the following conditional expression (12), where the focal length of the sixth lens with respect to the d-line is f6.
2.05<f6/f<3.30...(12) The imaging lens according to claim 1 ,
The imaging lens, wherein each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens is made of a glass material. The imaging lens according to claim 1 ,
The imaging lens has a total length Da on an optical axis, and satisfies the following conditional expression (13):
4.5<Da/f<4.8 (13) The imaging lens according to claim 1 ,
the object-side surface and the image-side surface of the seventh lens are aspheric. an imaging lens including, in order from an object side to an image side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, an aperture stop, a fourth lens having positive refractive power, a fifth lens having negative refractive power, a sixth lens having positive refractive power, and a seventh lens having positive refractive power, wherein the imaging lens satisfies the following formulas (1) and (2), where D3 is a thickness on the optical axis of the second lens, R2 is a radius of curvature of the image side surface of the first lens, and f is a focal length of the imaging lens with respect to a d-line;
an imaging element for converting an optical image formed through the imaging lens into an electrical signal;
An imaging device comprising:
0.12<D3/f<0.14...(1)
-1.3<R2/f<-0.90...(2)

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