Imaging lens and imaging device

Abstract

This imaging lens, constructed with six elements, is compact, lightweight, and inexpensive, yet possesses high optical performance thanks to its appropriately designed lens shape. [Solution] The imaging lens 10 according to this disclosure comprises, in order from the object side, 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 diaphragm 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, and the conditional expression, 0.6 < (R1 + R2) / (R1 - R2) < 0.8 (1) 0.14 <D1 / f (3) It satisfies the condition.

Description

Technical Field

[0001] The present disclosure relates to an imaging lens and an imaging device.

Background Art

[0002] For imaging lenses used in cameras including surveillance cameras and in-vehicle cameras, etc., it is required to be resistant to environmental changes and have good imaging performance across the entire screen. In addition, due to reasons such as limited mounting space for mounting the imaging lens on the camera, etc., the imaging lens is also required to be small and lightweight.

[0003] As single-focus imaging lenses capable of meeting the above requirements, the technologies described in Patent Documents 1 and 2 have been proposed. For example, Patent Document 1 discloses a lens unit that can be used well even in a harsh environment 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 has excellent compactness.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] For example, in-vehicle cameras are now used not only for conventional visual applications but also for sensing applications to detect objects, requiring even higher performance. With the increasing pixel count of solid-state image sensors such as CCDs (Charge Coupled Devices) and CMOS (Complementary Metal-Oxide Semiconductor Devices), the imaging lenses used in cameras are also required to have correspondingly good optical performance.

[0006] In view of the above-mentioned problems, the purpose of this disclosure is to provide an imaging lens and imaging device that are small, lightweight, and inexpensive due to their six-element configuration, while having high optical performance by appropriately setting the shape of the lenses. [Means for solving the problem]

[0007] A National lens according to one embodiment of this disclosure is (1) It is an imaging lens, The device comprises, in order from the object side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, an aperture diaphragm, a fourth lens having positive refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power. If R1 is the radius of curvature of the object side of the first lens, R2 is the radius of curvature of the image side of the first lens, dN4 / dT is the refractive index temperature coefficient of the fourth lens with respect to the d line in the temperature range of 20°C to 40°C, dN6 / dT is the refractive index temperature coefficient of the sixth lens with respect to the d line in the temperature range of 20°C to 40°C, and f is the focal length of the imaging lens with respect to the d line, then the conditional equation is: 0.6 < (R1 + R2) / (R1 - R2) < 0.8 (1) -1.1<(dN4 / dT+dN6 / dT) / f<-0.7 (2) It satisfies the condition.

[0008] (2) The imaging lens described in (1) above, If the axial thickness of the first lens is D1, then the conditional equation is: 0.14 < D1 / f (3) may be satisfied.

[0009] (3) The imaging lens according to (1) or (2) above, when the focal length of the second lens with respect to the d-line is f2, the conditional expression, -3.8 < f2 / f < -2 (4) may be satisfied.

[0010] (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.

[0011] (5) The imaging lens according to any one of (1) to (4) above, when the on-axis distance from the image side surface of the first lens to the object side surface of the second lens is D2, the conditional expression, 0.36 < D2 / f < 0.6 (5) may be satisfied.

[0012] (6) The imaging lens according to any one of (1) to (5) above, the conditional expression, -6.7 < R1 / f < -4.4 (6) may be satisfied.

[0013] (7) The imaging lens according to any one of (1) to (6) above, when the Abbe number of the third lens is ν3, the conditional expression, 4.7 < ν3 / f < 5.7 (7) may be satisfied.

[0014] (8) The imaging lens according to any one of (1) to (7) above, when the refractive index of the first lens is N1, the conditional expression, N1 / f < 0.34 (8) may be satisfied.

[0015] (9) The imaging lens according to any one of (1) to (8) above, the object side surface of the first lens may be a concave surface.

[0016] (10) The imaging lens according to any one of (1) to (9) above, when the overall length on the axis of the imaging lens is Da, the conditional expression, Da / f < 5.2 (9) may be satisfied.

[0017] (11) The imaging lens according to any one of (1) to (10) above, when the focal length of the first lens with respect to the d-line is f1, the conditional expression, -1.5 < f1 / f < -1.2 (10) may be satisfied.

[0018] (12) The imaging lens according to any one of (1) to (11) above, when the focal length of the third lens with respect to the d-line is f3, the conditional expression, 1.6 < f3 / f < 3.1 (11) may be satisfied.

[0019] (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.

[0020] (14) The imaging lens according to any one of (1) to (13) above, each of both surfaces of the sixth lens may be an aspherical surface.

[0021] (15) An imaging lens as described in any one of (1) to (14) above, If the focal length of the sixth lens with respect to the d line is f6, then the conditional equation is, 1.45 <f6 / f<1.8 (12) It may satisfy this condition.

[0022] (16) An imaging lens as described in any one of (1) to (15) above, Each of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens may be made of glass material.

[0023] (17) An imaging lens as described in any one of (1) to (16) above, If W is the half-angle of view of the light ray incident at the highest image height position on the image plane, then the conditional equation is: 48 <W (13) It may satisfy this condition.

[0024] (18) An imaging lens as described in any one of (1) to (17) above, If the focal length of the fifth lens with respect to the d line is f5, then the conditional equation is, -2.0 <f5 / f<-1.1 (14) It may satisfy this condition.

[0025] (19) An imaging lens as described in any one of (1) to (18) above, If the focal length of the fourth lens with respect to the d line is f4, then the conditional equation is, 1.2 <f4 / f<1.8 (15) It may satisfy this condition.

[0026] An imaging apparatus according to one embodiment of the present disclosure, (20) The imaging lens comprises, in order from the object side, a first lens with negative refractive power, a second lens with negative refractive power, a third lens with positive refractive power, an aperture diaphragm, a fourth lens with positive refractive power, a fifth lens with negative refractive power, and a sixth lens with positive refractive power. An image sensor that converts an optical image formed through the aforementioned imaging lens into an electrical signal, Equipped with, If R1 is the radius of curvature of the object side of the first lens, R2 is the radius of curvature of the image side of the first lens, dN4 / dT is the refractive index temperature coefficient of the fourth lens with respect to the d line in the temperature range of 20°C to 40°C, dN6 / dT is the refractive index temperature coefficient of the sixth lens with respect to the d line in the temperature range of 20°C to 40°C, and f is the focal length of the imaging lens with respect to the d line, then the conditional equation is: 0.6 < (R1 + R2) / (R1 - R2) < 0.8 (16) -1.1<(dN4 / dT+dN6 / dT) / f<-0.7 (17) It satisfies the condition. [Effects of the Invention]

[0027] According to one embodiment of the present disclosure, it is possible to provide an imaging lens and imaging device that are small, lightweight, and inexpensive due to their six-element configuration, while having high optical performance by appropriately setting the shape of the lenses. [Brief explanation of the drawing]

[0028] [Figure 1] This is a lens configuration diagram of the imaging lens according to Embodiment 1 of the present disclosure. [Figure 2A] Figure 1 is a graph showing the astigmatism of the imaging lens. [Figure 2B] Figure 1 is a graph showing the distortion aberration of the imaging lens. [Figure 3] This is a lens configuration diagram of the imaging lens according to Embodiment 2 of the present disclosure. [Figure 4A] Figure 3 is a graph showing the astigmatism of the imaging lens. [Figure 4B] Figure 3 is a graph showing the distortion aberration of the imaging lens. [Figure 5] This is a lens configuration diagram of the imaging lens according to Embodiment 3 of the present disclosure. [Figure 6A] Figure 5 is a graph showing the astigmatism of the imaging lens. [Figure 6B] Figure 5 is a graph showing the distortion aberration of the imaging lens. [Figure 7] This is a lens configuration diagram of the imaging lens according to Embodiment 4 of the present disclosure. [Figure 8A] Figure 7 is a graph showing the astigmatism of the imaging lens. [Figure 8B] Figure 7 is a graph showing the distortion aberration of the imaging lens. [Figure 9] This is a lens configuration diagram of the imaging lens according to Embodiment 5 of the present disclosure. [Figure 10A] Figure 9 is a graph showing the astigmatism of the imaging lens. [Figure 10B] Figure 9 is a graph showing the distortion aberration of the imaging lens. [Figure 11] This is a lens configuration diagram of the imaging lens according to Embodiment 6 of the present disclosure. [Figure 12A] Figure 11 is a graph showing the astigmatism of the imaging lens. [Figure 12B] Figure 11 is a graph showing the distortion aberration of the imaging lens. [Figure 13] This is a lens configuration diagram of the imaging lens according to Embodiment 7 of the present disclosure. [Figure 14A] Figure 13 is a graph showing the astigmatism of the imaging lens. [Figure 14B] Figure 13 is a graph showing the distortion aberration of the imaging lens. [Figure 15] This is a lens configuration diagram of the imaging lens according to Embodiment 8 of the present disclosure. [Figure 16A] Figure 15 is a graph showing the astigmatism of the imaging lens. [Figure 16B] Figure 15 is a graph showing the distortion aberration of the imaging lens. [Figure 17] This is a lens configuration diagram of the imaging lens according to Embodiment 9 of the present disclosure. [Figure 18A]Figure 17 is a graph showing the astigmatism of the imaging lens. [Figure 18B] Figure 17 is a graph showing the distortion aberration of the imaging lens. [Modes for carrying out the invention]

[0029] The following describes in detail an imaging lens 10 and imaging device 1 according to one embodiment of this disclosure, with reference to the attached drawings. More specifically, the configuration and function of the imaging lens 10 and imaging device 1 common to each embodiment described later will be explained. In each attached drawing showing the configuration of the imaging lens 10 and imaging device 1, the "object side" corresponds to the left side and the "image side" corresponds to the right side. The figures used in the following description are schematic, and the dimensional ratios and other aspects shown in the drawings do not necessarily correspond to those in reality.

[0030] The lens configuration of the imaging lens 10 and imaging device 1 according to one embodiment will be mainly described with reference to Figure 1, which will be described later and shows the configuration of the imaging lens 10 and imaging device 1 of Embodiment 1.

[0031] The imaging device 1 includes an imaging lens 10 and an image sensor 20 that converts the 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 an object by having the imaging lens 10 form an image of the object onto the image plane 21 of the image sensor 20.

[0032] The imaging lens 10 has, arranged in order from the object side, 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, a first flat plate 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 fixed-focus imaging lens with a 6-element configuration. 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 glass material.

[0033] The first lens 110 has a spherical shape. Each of the two surfaces of the first lens 110 is concave. The second lens 120 has a spherical shape. Each of the two surfaces of the second lens 120 is concave. The third lens 130 has a spherical shape. Each of the two surfaces of the third lens 130 is convex. The fourth lens 140 has a spherical shape. Each of the two surfaces of the fourth lens 140 is convex. The fifth lens 150 has a spherical shape. Each of the two surfaces of the fifth lens 150 is concave. Each of the two surfaces of the sixth lens 160 is aspherical. The first flat plate 180a includes optical elements such as an IR (Infrared) cut filter. The second flat plate 180b includes optical elements such as a LID glass placed against the image sensor 20. The LID glass is a cover glass used against the image sensor 20 as an image sensor.

[0034] 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 this disclosure, "substantially composed" means that the optical elements substantially constituting the imaging lens 10 are the six lenses from the first lens 110 to the sixth lens 160, but the imaging lens 10 may also have other optical elements other than lenses, such as lenses that have substantially no power, as well as an aperture and cover glass. For example, in addition to the first lens 110 to the sixth lens 160, the imaging lens 10 has an aperture diaphragm 170, and a first plate 180a and a second plate 180b.

[0035] The imaging lens 10 includes, in order from the object side, 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 diaphragm 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.

[0036] In a wide-angle imaging lens 10, the focal length needs to be shortened to obtain a wide field of view. However, due to the mechanical constraints of the imaging lens 10, the back focus must be longer than the focal length. Therefore, a lens with negative refractive power is placed in front of the imaging lens 10, causing the light incident on the imaging lens 10 from the object side to diverge once, and then being focused by a lens with positive refractive power behind it. This makes it possible to move the principal point of the lens system behind the imaging lens 10, thereby securing a back focus that is longer than the focal length.

[0037] More specifically, the first lens 110 and the second lens 120, which have negative refractive power, diverge the light, and the third lens 130, the fourth lens 140, and the sixth lens 160, which have positive refractive power, focus the light. By placing the first lens 110 and the second lens 120, which are negative lenses, on the object side of the imaging lens 10, sufficient negative refractive power can be obtained to place the principal point behind the image. By placing the third lens 130, which has positive refractive power, in front of the aperture diaphragm 170, good correction of chromatic aberration is possible. By placing the fourth lens 140 and the sixth lens 160, which have positive refractive power, after the aperture diaphragm 170, the angle of incidence of light to the image plane 21 can be reduced, and aberrations can be corrected well.

[0038] The aperture diaphragm 170 is positioned between the third lens 130 and the fourth lens 140. If the aperture diaphragm 170 were positioned closer to the image than the fourth lens 140, the imaging lens 10 would become larger, which is undesirable. In addition, if the aperture diaphragm 170 were positioned closer to the object than the third lens 130, it would be difficult to widen the angle of the imaging lens 10, which is also undesirable. Therefore, by positioning the aperture diaphragm 170 between the third lens 130 and the fourth lens 140 as described above, the imaging lens 10 can achieve good correction of various aberrations and a compact lens system.

[0039] The functions of the imaging lens 10 and imaging device 1 according to one embodiment will be described in detail.

[0040] The imaging lens 10 satisfies the following conditions (1) and (2). 0.6 < (R1 + R2) / (R1 - R2) < 0.8 (1) -1.1<(dN4 / dT+dN6 / dT) / f<-0.7 (2) However, R1 is the radius of curvature of the object side of the first lens 110. R2 is the radius of curvature of the image side of the first lens 110. dN4 / dT is the refractive index temperature coefficient of the fourth lens 140 for the d line (wavelength λ = 587.56 nm) in the temperature range from 20°C to 40°C. dN6 / dT is the refractive index temperature coefficient of the sixth lens 160 for the d line in the temperature range from 20°C to 40°C. f is the focal length of the imaging lens 10 for the d line.

[0041] Condition (1) relates the respective radii of curvature of both surfaces of the first lens 110. If the value of (R1+R2) / (R1-R2) is greater than or equal to the upper limit of 0.8, the difference in radii of curvature between the two concave surfaces of the first lens 110 becomes too large, making it difficult to correct astigmatism. If the value of (R1+R2) / (R1-R2) is less than or equal to the lower limit of 0.6, the radii of curvature of the two concave surfaces of the first lens 110 become too similar to each other, resulting in significant field curvature. When condition (1) is satisfied, astigmatism correction becomes easier and the occurrence of field curvature is suppressed.

[0042] Conditional equation (2) relates the refractive index temperature coefficient of the fourth lens 140 and the refractive index temperature coefficient of the sixth lens 160 to the focal length of the imaging lens 10. If the value of (dN4 / dT+dN6 / dT) / f is greater than or equal to the upper limit of -0.7, the refractive index temperature coefficient of the convex lenses, including the fourth lens 140 and the sixth lens 160, is too high, making it difficult to reduce focus shift during temperature changes. If the value of (dN4 / dT+dN6 / dT) / f is less than or equal to the lower limit of -1.1, the refractive index temperature coefficient of the convex lenses, including the fourth lens 140 and the sixth lens 160, is too low, resulting in overcorrection instead of canceling out the focus shift caused by the concave lens included in the imaging lens 10, making it difficult to reduce focus shift. When conditional equation (2) is satisfied, it becomes easy to reduce focus shift during temperature changes.

[0043] The imaging lens 10 may also satisfy the following condition (3). 0.14 <D1 / f (3) However, D1 is the on-axial thickness of the first lens 110. That is, D1 is the distance from the object side of the first lens 110 to the image side of the first lens 110 on the optical axis Ax of the imaging lens 10 shown in Figure 1.

[0044] Condition (3) relates the axial thickness of the first lens 110 to the focal length of the imaging lens 10. If the value of D1 / f falls below the lower limit of 0.14, the axial thickness of the first lens 110 is too thin, reducing the refractive power of the first lens 110 as a biconcave lens, making it difficult to correct astigmatism. In addition, the thin axial thickness makes it difficult to manufacture the first lens 110. Furthermore, pressure from retainers and other components that hold the first lens 110 may cause it to crack. When condition (3) is satisfied, astigmatism correction and manufacturing of the first lens 110 become easier, and damage to the first lens 110 due to retainers and other components is suppressed.

[0045] The imaging lens 10 may also satisfy the following condition (4). -3.8 <f2 / f<-2 (4) However, f2 is the focal length of the second lens 120 relative to the d line.

[0046] Condition (4) relates the focal length of the second lens 120 to the focal length of the imaging lens 10. When the value of f2 / f is less than the upper limit of -2, the refractive power of the second lens 120 as a concave lens is moderately suppressed, and astigmatism correction is good. When the value of f2 / f is less than or equal to the lower limit of -3.8, the axial chromatic aberration generated in the second lens 120 weakens, and as a result, it becomes difficult to correct axial chromatic aberration in the entire imaging lens 10. When condition (4) is satisfied, it becomes easy to correct axial chromatic aberration in the entire imaging lens 10.

[0047] The imaging lens 10 has a second lens 120, each of which has a concave surface. This allows for the easy formation of a flat receiving portion that can contact the first lens 110 and spacers on a flat surface without requiring any additional processing of the second lens 120. This makes it possible to realize a configuration with low tolerance sensitivity. As shown in Figure 1, the flat receiving portion is formed on the second lens 120 in the region furthest from the optical axis Ax, where the first lens 110 and the second lens 120 are in contact with each other.

[0048] For example, if the lens surface is convex, it is necessary to additionally form a flat receiving portion in the region furthest from the optical axis on the outer circumference 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 be misaligned. As a result, when the convex lens is incorporated into the lens system, it may not fit within the assembly tolerances. Since it is not easy to additionally form a flat receiving portion on the outer circumference of a convex lens surface, it is desirable that the second lens 120 has a concave lens surface with a flat receiving portion as a result of normal processing.

[0049] The imaging lens 10 may also satisfy the following condition (5). 0.36 <D2 / f<0.6 (5) However, D2 is the on-axis distance from the image side of the first lens 110 to the object side of the second lens 120. That is, D2 is the distance from the image side of the first lens 110 to the object side of the second lens 120 on the optical axis Ax of the imaging lens 10 shown in Figure 1.

[0050] Condition (5) relates the on-axial distance between the first lens 110 and the second lens 120 to the focal length of the imaging lens 10. When the value of D2 / f is less than the upper limit of 0.6, the optical path difference that occurs between the optical axis Ax and a position away from the optical axis Ax in the air lens between the first lens 110 and the second lens 120 is suppressed. This suppresses the occurrence of chromatic aberration. When the value of D2 / f is less than or equal to the lower limit of 0.36, the distance between the first lens 110 and the second lens 120 becomes extremely short, making it difficult to correct spherical aberration. When condition (5) is satisfied, it becomes easy to correct spherical aberration.

[0051] The imaging lens 10 may also satisfy the following condition (6). -6.7 <R1 / f<-4.4 (6)

[0052] Conditional equation (6) relates the radius of curvature of the object side of the first lens 110 to the focal length of the imaging lens 10. When the value of R1 / f is greater than or equal to the upper limit of -4.4, the off-axis focal length is too long, making correction difficult and causing field curvature. When the value of R1 / f is less than or equal to the lower limit of -6.7, the off-axis refractive power is too large, resulting in overcorrection and negative field curvature. When conditional equation (6) is satisfied, the occurrence of field curvature is suppressed.

[0053] The imaging lens 10 may also satisfy the following condition (7). 4.7 < ν³ / f < 5.7 (7) However, ν3 is the Abbe number of the third lens 130.

[0054] Conditional equation (7) relates the Abbe number of the third lens 130 to the focal length of the imaging lens 10. When the value of ν3 / f is greater than or equal to the upper limit of 5.7, the Abbe number of the third lens 130, which is a convex lens on the object side of the aperture diaphragm 170, becomes large, causing significant lateral chromatic aberration. When conditional equation (7) is satisfied, the occurrence of lateral chromatic aberration is suppressed. When the value of ν3 / f is greater than the lower limit of 4.7, the axial chromatic aberration generated by the third lens 130, which is a convex lens, is suppressed, and correction of axial chromatic aberration across the entire imaging lens 10 becomes possible.

[0055] The imaging lens 10 may further satisfy the following condition (8). N1 / f<0.34 (8) However, N1 is the refractive index of the first lens 110.

[0056] Condition (8) relates the refractive index of the first lens 110 to the focal length of the imaging lens 10. When the value of N1 / f exceeds the upper limit of 0.34, the refractive power of the first lens 110 increases, and for example, the refractive power becomes significant at intermediate image heights. This causes significant spherical aberration. When condition (8) is satisfied, the occurrence of spherical aberration is suppressed.

[0057] The imaging lens 10 has a concave surface on the object side of the first lens 110, which allows for easy formation of a retaining structure such as a retainer without requiring any additional processing of the first lens 110. In addition, when the reflected light from the image plane 21 of the imaging lens 10 is incident on the object side of the first lens 110, the re-reflected light tends to diverge rather than converge. Therefore, it is possible to suppress the occurrence of ghosting caused by such re-reflected light re-imaging at the image plane 21.

[0058] The imaging lens 10 may further satisfy the following condition (9). Da / f<5.2 (9) However, Da is the total length of the imaging lens 10 along the optical axis Ax. That is, Da is the distance from the object side of the first lens 110 to the image plane 21 along the optical axis Ax of the imaging lens 10 shown in Figure 1.

[0059] Conditional equation (9) relates the total length of the imaging lens 10 to 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 increases in each air lens, thereby suppressing astigmatism. In addition, this leads to miniaturization of the imaging lens 10 in the overall length and radial direction, improving the design flexibility of the camera housing.

[0060] The imaging lens 10 may further satisfy the following condition (10). -1.5 <f1 / f<-1.2 (10) However, f1 is the focal length of the first lens 110 with respect to the d line.

[0061] Conditional equation (10) relates the focal length of the first lens 110 to the focal length of the imaging lens 10. If the value of f1 / f is greater than or equal to 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, causing significant field curvature. When conditional equation (10) is satisfied, the occurrence of field curvature is suppressed. Since the value of f1 / f is greater than the lower limit of -1.5, the refractive power of the first lens 110 does not become too small, making it possible to correct axial chromatic aberration well.

[0062] The imaging lens 10 may also satisfy the following condition (11). 1.6 <f3 / f<3.1 (11) However, f3 is the focal length of the third lens 130 relative to the d line.

[0063] Condition (11) relates the focal length of the third lens 130 to the focal length of the imaging lens 10. If the value of f3 / f is 3.1 or higher, the refractive power of the third lens 130, which is a convex lens in front of the aperture diaphragm 170, becomes small, causing field curvature. If the value of f3 / f is 1.6 or lower, the refractive power of the third lens 130, which is a convex lens in the imaging lens 10, becomes too large, making it difficult to correct the axial chromatic aberration generated by that convex lens. When condition (11) is satisfied, the occurrence of field curvature is suppressed, and the correction of axial chromatic aberration generated by that convex lens becomes easier.

[0064] The imaging lens 10 is formed by combining the fourth lens 140 and the fifth lens 150 as a cemented lens. This allows the fourth lens 140 and the fifth lens 150, which have high axial misalignment sensitivity, to be configured as a cemented lens, thereby realizing an optical system with low tolerance sensitivity. In addition, the imaging lens 10 can reduce the number of components by using a cemented lens, thereby reducing the workload for assembly into the imaging lens 10.

[0065] In the imaging lens 10, each of the six surfaces of the sixth lens 160 is aspherical, so the sixth lens 160 closest to the image plane 21 has an aspherical shape, making it easy to adjust the angle of incidence of light to the image sensor 20. As a result, spherical aberration and astigmatism are easily corrected.

[0066] The imaging lens 10 may further satisfy the following condition (12). 1.45 <f6 / f<1.8 (12) However, f6 is the focal length of the sixth lens 160 relative to the d line.

[0067] Conditional equation (12) relates the focal length of the sixth lens 160 to the focal length of the imaging lens 10. When the value of f6 / f is greater than or equal to 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 tilt towards the object, making it difficult to correct for field curvature. When conditional equation (12) is satisfied, it becomes easier to correct for field curvature. When the value of f6 / f is greater 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. As a result, the image plane 21 does not tilt towards the image, and it becomes easier to correct for field curvature.

[0068] The imaging lens 10 is designed so that the first lens 110, second lens 120, third lens 130, fourth lens 140, fifth lens 150, and sixth lens 160 are each made of glass material, thereby suppressing yellowing due to ultraviolet light and changes in optical properties due to temperature changes.

[0069] The imaging lens 10 may also satisfy the following condition (13). 48 <W (13) However, W is the half-angle of view of the light ray incident at the maximum image height position on the image plane 21.

[0070] Conditional equation (13) is an equation relating to the angle of view of the entire imaging lens 10 system. If the value of W is less than or equal to the lower limit of 48, it becomes difficult to secure the imaging range that an imaging device 1 used in, for example, an in-vehicle camera should satisfy. When conditional equation (13) is satisfied, the imaging range that an imaging device 1 used in, for example, an in-vehicle camera should satisfy can be easily secured.

[0071] The imaging lens 10 may further satisfy the following condition (14). -2.0 <f5 / f<-1.1 (14) However, f5 is the focal length of the 5th lens 150 relative to the d line.

[0072] Conditional equation (14) relates the focal length of the fifth lens 150 to the focal length of the imaging lens 10. When the value of f5 / f is greater than or equal to the upper limit of -1.1, the refractive power of the fifth lens 150 increases, and lateral chromatic aberration is greatly increased in the reverse direction by the fifth lens 150, which is a concave lens on the image side of the aperture diaphragm 170. When the value of f5 / f is less than or equal to the lower limit of -2.0, the refractive power of the negative fifth lens 150, which cancels out the axial chromatic aberration generated by the positive fourth lens 140, decreases, making it difficult to correct axial chromatic aberration. When conditional equation (14) is satisfied, the occurrence of lateral chromatic aberration in the reverse direction is suppressed, and correction of axial chromatic aberration becomes easier.

[0073] The imaging lens 10 may further satisfy the following condition (15). 1.2 <f4 / f<1.8 (15) However, f4 is the focal length of the fourth lens 140 relative to the d line.

[0074] Condition (15) relates the focal length of the fourth lens 140 to the focal length of the imaging lens 10. When the value of f4 / f is 1.8 or higher, the refractive power of the convex fourth lens 140 decreases, causing the image plane 21 to tilt towards the image side, making it difficult to correct field curvature. When the value of f4 / f is 1.2 or lower, the refractive power of the positive fourth lens 140 becomes too high, making it difficult to correct axial chromatic aberration with the negative fifth lens 150. When condition (15) is satisfied, it becomes easy to correct field curvature, and it also becomes easy to correct axial chromatic aberration with the negative fifth lens 150.

[0075] (Examples) Next, the lens configuration of the embodiment relating to the imaging lens 10 of this disclosure will be mainly described. More specifically, Embodiments 1 to 9 with specific numerical values ​​for the imaging lens 10 will be shown. Embodiments 1 to 9 have the characteristics of the embodiment described above with respect to the positive or negative refractive power of each lens, the surface shape, and the parameters shown in conditional equations (1) to (15).

[0076] In Examples 1 to 9, the focal length f of the imaging lens 10, the total length Da of the imaging lens 10 on the optical axis Ax, and the F-number and image height are as shown in Table 1. In the data for each example in Table 1, the values ​​derived from the lens specifications, including the focal length f, are also values ​​relative to the d line unless otherwise specified. [Table 1]

[0077] In Examples 1 to 9, the parameter values ​​included in each of the conditional expressions (1) to (15) are as shown in Table 2 below. [Table 2]

[0078] In the basic lens data for each embodiment, the number i (where i is a natural number) in the lens specifications is the surface number assigned sequentially from the object side to all the lenses included in the imaging lens 10, the aperture diaphragm 170, and each surface of the first plate 180a and the second plate 180b. Ri is the radius of curvature of the i-th surface. Di is the distance between the i-th surface and the (i+1)-th surface on the optical axis Ax. Nd is the refractive index for the d-line. νd is the Abbe number for the d-line.

[0079] In all the specifications listed below, the unit of length, such as the radius of curvature Ri and the interplanar spacing Di, is millimeters (mm) unless otherwise specified, and the unit of length is omitted in each table. However, this is not limited to the imaging lens 10, as equivalent optical performance can be obtained in both proportional magnification and proportional reduction.

[0080] The aspherical shape of the lens described in the following embodiment is expressed by the following equation (16), i.e., the aspherical equation, where the direction from the object side to the image side is positive, k is the cone coefficient, A is the 4th-order aspherical coefficient, B is the 6th-order aspherical coefficient, C is the 8th-order aspherical coefficient, and D is the 10th-order aspherical coefficient. Here, h is the height of the ray, c is the reciprocal of the central radius of curvature, and Z is the depth from the tangent plane to the vertex of the surface.

[0081]

number

[0082] (Example 1) Figure 1 is a lens configuration diagram of the imaging lens 10 according to Embodiment 1 of this disclosure. Figure 1 shows the lens configuration of the imaging lens 10 according to Embodiment 1 in an optical cross-section.

[0083] As shown in Figure 1, in the imaging lens 10 of Embodiment 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 having negative refractive power and a spherical shape. The third lens 130 is a biconvex lens having positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens having positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens having negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens having positive refractive power and an aspherical shape.

[0084] In Figure 1, D1 corresponds to the on-axial thickness of the first lens 110 and is the distance on the optical axis Ax between plane S1 and plane S2. D2 is the on-axial distance between plane S2 and plane S3. D3 corresponds to the on-axial thickness of the second lens 120 and is the distance on the optical axis Ax between plane S3 and plane S4. D4 is the on-axial distance between plane S4 and plane S5. D5 corresponds to the on-axial thickness of the third lens 130 and is the distance on the optical axis Ax between plane S5 and plane S6. D6 is the on-axial distance between plane S6 and plane S7. D7 is the on-axial distance between plane S7 and plane S8.

[0085] D8 corresponds to the on-axial thickness of the fourth lens 140 and is the distance on the optical axis Ax between plane S8 and plane S9. D9 corresponds to the on-axial thickness of the fifth lens 150 and is the distance on the optical axis Ax between plane S9 and plane S10. D10 is the on-axial distance between plane S10 and plane S11. D11 corresponds to the on-axial thickness of the sixth lens 160 and is the distance on the optical axis Ax between plane S11 and plane S12. D12 is the on-axial distance between plane S12 and plane S13. D13 corresponds to the on-axial thickness of the first plate 180a and is the distance on the optical axis Ax between plane S13 and plane S14. D14 is the on-axial distance between plane S14 and plane S15. D15 corresponds to the on-axial thickness of the second plate 180b and is the distance on the optical axis Ax between plane S15 and plane S16. D16 is the on-axis distance between plane S16 and image plane 21.

[0086] The above explanation regarding the interplanar spacing Di also applies to the following other embodiments. The interplanar spacing Di is shown only in Figure 1 and is omitted in the other drawings.

[0087] Table 3 shows the basic lens data, including the specifications of the imaging lens 10 according to Example 1. In Table 3, for surfaces S11 and S12, which are aspherical surfaces indicated by *, the value of the radius of curvature Ri represents the paraxial radius of curvature. [Table 3]

[0088] Table 4 shows the aspherical data, including the aspherical coefficient, of the imaging lens 10 according to Example 1. The aspherical data shown in Table 4 are for surfaces S11 and S12 of the sixth lens 160, respectively. [Table 4]

[0089] Figures 2A and 2B are aberration diagrams of the imaging lens 10 shown in Figure 1.

[0090] Figure 2A is a graph showing the astigmatism of the imaging lens 10 in Figure 1. In Figure 2A, the vertical axis represents the incident height on the entrance pupil normalized to a pupil diameter of 1, and the horizontal axis represents the shift in the image formation position. Each line in the graph represents the astigmatism (mm) for light of each wavelength shown on the right of the graph. "S" means the value on the sagittal image plane, and "T" means the value on the tangential image plane.

[0091] Figure 2B is a graph showing the distortion aberration of the imaging lens 10 in Figure 1. In Figure 2B, the vertical axis represents the incident height on the entrance pupil normalized to a pupil diameter of 1, and the horizontal axis represents the shift in the image formation position. Each line in the graph represents the distortion aberration (%) for light of each wavelength shown on the right of the graph.

[0092] As shown in Figures 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.

[0093] The above explanation regarding the aberration diagrams also applies to the aberration diagrams shown in other embodiments, so further explanation will be omitted below.

[0094] (Example 2) Figure 3 is a lens configuration diagram of the imaging lens 10 according to Embodiment 2 of this disclosure. Figure 3 shows the lens configuration of the imaging lens 10 according to Embodiment 2 in an optical cross-section.

[0095] As shown in Figure 3, in the imaging lens 10 of Embodiment 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 having negative refractive power and a spherical shape. The third lens 130 is a biconvex lens having positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens having positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens having negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens having positive refractive power and an aspherical shape.

[0096] Table 5 shows the basic lens data, including the specifications of the imaging lens 10 according to Example 2. In Table 5, for surfaces S11 and S12, which are aspherical surfaces indicated by *, the value of the radius of curvature Ri represents the paraxial radius of curvature. [Table 5]

[0097] Table 6 shows the aspherical data, including the aspherical coefficient, of the imaging lens 10 according to Example 2. The aspherical data shown in Table 6 are for surfaces S11 and S12 of the sixth lens 160, respectively. [Table 6]

[0098] Figures 4A and 4B are aberration diagrams of the imaging lens 10 in Figure 3. Figure 4A is a graph showing the astigmatism of the imaging lens 10 in Figure 3. Figure 4B is a graph showing the distortion of the imaging lens 10 in Figure 3. As shown in Figures 4A and 4B, according to Embodiment 2, aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

[0099] (Example 3) Figure 5 is a lens configuration diagram of the imaging lens 10 according to Embodiment 3 of this disclosure. Figure 5 shows the lens configuration of the imaging lens 10 according to Embodiment 3 in an optical cross-section.

[0100] As shown in Figure 5, in the imaging lens 10 of Embodiment 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 having negative refractive power and a spherical shape. The third lens 130 is a biconvex lens having positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens having positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens having negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens having positive refractive power and an aspherical shape.

[0101] Table 7 shows the basic lens data, including the specifications of the imaging lens 10 according to Example 3. In Table 7, for surfaces S11 and S12, which are aspherical surfaces indicated by *, the value of the radius of curvature Ri represents the paraxial radius of curvature. [Table 7]

[0102] Table 8 shows the aspherical data, including the aspherical coefficient, of the imaging lens 10 according to Example 3. The aspherical data shown in Table 8 is for surfaces S11 and S12 of the sixth lens 160, respectively. [Table 8]

[0103] Figures 6A and 6B are aberration diagrams of the imaging lens 10 shown in Figure 5. Figure 6A is a graph showing the astigmatism of the imaging lens 10 shown in Figure 5. Figure 6B is a graph showing the distortion of the imaging lens 10 shown in Figure 5. As shown in Figures 6A and 6B, according to Embodiment 3, aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

[0104] (Example 4) Figure 7 is a lens configuration diagram of the imaging lens 10 according to Embodiment 4 of this disclosure. Figure 7 shows the lens configuration of the imaging lens 10 according to Embodiment 4 in an optical cross-section.

[0105] As shown in Figure 7, in the imaging lens 10 of Embodiment 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 having negative refractive power and a spherical shape. The third lens 130 is a biconvex lens having positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens having positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens having negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens having positive refractive power and an aspherical shape.

[0106] Table 9 shows the basic lens data, including the specifications of the imaging lens 10 according to Example 4. In Table 9, for surfaces S11 and S12, which are aspherical surfaces indicated by *, the value of the radius of curvature Ri represents the paraxial radius of curvature. [Table 9]

[0107] Table 10 shows the aspherical data, including the aspherical coefficient, of the imaging lens 10 according to Example 4. The aspherical data shown in Table 10 are for surfaces S11 and S12 of the sixth lens 160, respectively. [Table 10]

[0108] Figures 8A and 8B are aberration diagrams of the imaging lens 10 shown in Figure 7. Figure 8A is a graph showing the astigmatism of the imaging lens 10 shown in Figure 7. Figure 8B is a graph showing the distortion of the imaging lens 10 shown in Figure 7. As shown in Figures 8A and 8B, according to Embodiment 4, aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

[0109] (Example 5) Figure 9 is a lens configuration diagram of the imaging lens 10 according to Embodiment 5 of this disclosure. Figure 9 shows the lens configuration of the imaging lens 10 according to Embodiment 5 in an optical cross-section.

[0110] As shown in Figure 9, in the imaging lens 10 of Embodiment 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 having negative refractive power and a spherical shape. The third lens 130 is a biconvex lens having positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens having positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens having negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens having positive refractive power and an aspherical shape.

[0111] Table 11 shows the basic lens data, including the specifications of the imaging lens 10 according to Example 5. In Table 11, for surfaces S11 and S12, which are aspherical surfaces indicated by *, the value of the radius of curvature Ri represents the paraxial radius of curvature. [Table 11]

[0112] Table 12 shows the aspherical data, including the aspherical coefficient, of the imaging lens 10 according to Example 5. The aspherical data shown in Table 12 are for surfaces S11 and S12 of the sixth lens 160, respectively. [Table 12]

[0113] Figures 10A and 10B are aberration diagrams of the imaging lens 10 shown in Figure 9. Figure 10A is a graph showing the astigmatism of the imaging lens 10 shown in Figure 9. Figure 10B is a graph showing the distortion of the imaging lens 10 shown in Figure 9. As shown in Figures 10A and 10B, according to Example 5, aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

[0114] (Example 6) Figure 11 is a lens configuration diagram of the imaging lens 10 according to Embodiment 6 of this disclosure. Figure 11 shows the lens configuration of the imaging lens 10 according to Embodiment 6 in an optical cross-section.

[0115] As shown in Figure 11, in the imaging lens 10 of Embodiment 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 having negative refractive power and a spherical shape. The third lens 130 is a biconvex lens having positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens having positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens having negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens having positive refractive power and an aspherical shape.

[0116] Table 13 shows the basic lens data, including the specifications of the imaging lens 10 according to Example 6. In Table 13, for surfaces S11 and S12, which are aspherical surfaces indicated by *, the value of the radius of curvature Ri represents the paraxial radius of curvature. [Table 13]

[0117] Table 14 shows the aspherical data, including the aspherical coefficient, of the imaging lens 10 according to Example 6. The aspherical data shown in Table 14 are for surfaces S11 and S12 of the sixth lens 160, respectively. [Table 14]

[0118] Figures 12A and 12B are aberration diagrams of the imaging lens 10 shown in Figure 11. Figure 12A is a graph showing the astigmatism of the imaging lens 10 shown in Figure 11. Figure 12B is a graph showing the distortion of the imaging lens 10 shown in Figure 11. As shown in Figures 12A and 12B, according to Example 6, aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

[0119] (Example 7) Figure 13 is a lens configuration diagram of the imaging lens 10 according to Embodiment 7 of this disclosure. Figure 13 shows the lens configuration of the imaging lens 10 according to Embodiment 7 in an optical cross-section.

[0120] As shown in Figure 13, in the imaging lens 10 of Embodiment 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 having negative refractive power and a spherical shape. The third lens 130 is a biconvex lens having positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens having positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens having negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens having positive refractive power and an aspherical shape.

[0121] Table 15 shows the basic lens data, including the specifications of the imaging lens 10 according to Example 7. In Table 15, for surfaces S11 and S12, which are aspherical surfaces indicated by *, the value of the radius of curvature Ri represents the paraxial radius of curvature. [Table 15]

[0122] Table 16 shows the aspherical data, including the aspherical coefficient, of the imaging lens 10 according to Example 7. The aspherical data shown in Table 16 are for surfaces S11 and S12 of the sixth lens 160, respectively. [Table 16]

[0123] Figures 14A and 14B are aberration diagrams of the imaging lens 10 shown in Figure 13. Figure 14A is a graph showing the astigmatism of the imaging lens 10 shown in Figure 13. Figure 14B is a graph showing the distortion of the imaging lens 10 shown in Figure 13. As shown in Figures 14A and 14B, according to Example 7, aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

[0124] (Example 8) Figure 15 is a lens configuration diagram of the imaging lens 10 according to Embodiment 8 of this disclosure. Figure 15 shows the lens configuration of the imaging lens 10 according to Embodiment 8 in an optical cross-section.

[0125] As shown in Figure 15, in the imaging lens 10 of Embodiment 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 having negative refractive power and a spherical shape. The third lens 130 is a biconvex lens having positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens having positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens having negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens having positive refractive power and an aspherical shape.

[0126] Table 17 shows the basic lens data, including the specifications of the imaging lens 10 according to Example 8. In Table 17, for surfaces S11 and S12, which are aspherical surfaces indicated by *, the value of the radius of curvature Ri represents the paraxial radius of curvature. [Table 17]

[0127] Table 18 shows the aspherical data, including the aspherical coefficient, of the imaging lens 10 according to Example 8. The aspherical data shown in Table 18 is for surfaces S11 and S12 of the sixth lens 160, respectively. [Table 18]

[0128] Figures 16A and 16B are aberration diagrams of the imaging lens 10 shown in Figure 15. Figure 16A is a graph showing the astigmatism of the imaging lens 10 shown in Figure 15. Figure 16B is a graph showing the distortion of the imaging lens 10 shown in Figure 15. As shown in Figures 16A and 16B, according to Example 8, aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

[0129] (Example 9) Figure 17 is a lens configuration diagram of the imaging lens 10 according to Embodiment 9 of this disclosure. Figure 17 shows the lens configuration of the imaging lens 10 according to Embodiment 9 in an optical cross-section.

[0130] As shown in Figure 17, in the imaging lens 10 of Embodiment 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 having negative refractive power and a spherical shape. The third lens 130 is a biconvex lens having positive refractive power and a spherical shape. The fourth lens 140 is a biconvex lens having positive refractive power and a spherical shape. The fifth lens 150 is a biconcave lens having negative refractive power and a spherical shape. The sixth lens 160 is a biconvex lens having positive refractive power and an aspherical shape.

[0131] Table 19 shows the basic lens data, including the specifications of the imaging lens 10 according to Example 9. In Table 19, for surfaces S11 and S12, which are aspherical surfaces indicated by *, the value of the radius of curvature Ri represents the paraxial radius of curvature. [Table 19]

[0132] Table 20 shows the aspherical data, including the aspherical coefficient, of the imaging lens 10 according to Example 9. The aspherical data shown in Table 20 is for surfaces S11 and S12 of the sixth lens 160, respectively. [Table 20]

[0133] Figures 18A and 18B are aberration diagrams of the imaging lens 10 shown in Figure 17. Figure 18A is a graph showing the astigmatism of the imaging lens 10 shown in Figure 17. Figure 18B is a graph showing the distortion of the imaging lens 10 shown in Figure 17. As shown in Figures 18A and 18B, according to Embodiment 9, aberrations such as astigmatism and distortion are well corrected, and an imaging lens 10 with excellent imaging performance is obtained.

[0134] According to the imaging lens 10 and imaging device 1 of one embodiment of this disclosure described above, the six-element configuration makes it small, lightweight, and inexpensive, while high optical performance can be achieved by appropriately setting the shape of the lens. As a result, it is possible to realize a compact imaging lens 10 and imaging device 1 with high optical performance that can be mounted on cameras, including surveillance cameras and in-vehicle cameras.

[0135] By satisfying condition (1), the imaging lens 10 can easily correct astigmatism and suppress the occurrence of field curvature. By satisfying condition (2), the imaging lens 10 can easily reduce focus shift during temperature changes.

[0136] By satisfying condition (3), the imaging lens 10 facilitates the correction of astigmatism and the processing of the first lens 110, while also suppressing damage to the first lens 110 caused by retainers or the like.

[0137] By satisfying condition (4), the imaging lens 10 can easily correct axial chromatic aberration across the entire imaging lens 10.

[0138] Since each of the two sides of the imaging lens 10 (the second lens 120) is concave, a flat receiving portion can be easily formed that can make planar contact with the first lens 110 and spacers, etc., without requiring any additional processing of the second lens 120.

[0139] The imaging lens 10 can easily correct spherical aberration by satisfying condition (5).

[0140] The imaging lens 10 can suppress the occurrence of field curvature by satisfying condition (6).

[0141] The imaging lens 10 can suppress the occurrence of lateral chromatic aberration by satisfying condition (7). In addition, the imaging lens 10 can correct axial chromatic aberration across the entire imaging lens 10.

[0142] The imaging lens 10 can suppress the occurrence of spherical aberration by satisfying condition (8).

[0143] The imaging lens 10 has a concave surface on the object side of the first lens 110, which allows for easy formation of a retaining structure such as a retainer without requiring any additional processing of the first lens 110. In addition, the imaging lens 10 can suppress the generation of ghosting.

[0144] The imaging lens 10 can suppress astigmatism by satisfying condition (9). In addition, the imaging lens 10 can be miniaturized in the overall length and radial direction, improving the design flexibility of the camera housing.

[0145] The imaging lens 10 can suppress the occurrence of field curvature by satisfying condition (10). In addition, the imaging lens 10 can also effectively correct axial chromatic aberration.

[0146] By satisfying condition (11), the imaging lens 10 suppresses the occurrence of field curvature and makes it possible to easily correct axial chromatic aberration occurring in the third lens 130.

[0147] The imaging lens 10 is formed by a cemented lens consisting of a fourth lens 140 and a fifth lens 150, which enables the realization of an optical system with low tolerance sensitivity. In addition, the imaging lens 10 reduces the workload for assembly into the imaging lens 10.

[0148] The imaging lens 10 has aspherical surfaces on both sides of the sixth lens 160, allowing for easy adjustment of the angle of incidence of light to the image sensor 20. As a result, the imaging lens 10 can easily correct spherical aberration and astigmatism.

[0149] The imaging lens 10 can easily correct field curvature by satisfying condition (12). In addition, the imaging lens 10 can also have a low tolerance sensitivity.

[0150] The imaging lens 10 is designed so that the first lens 110, second lens 120, third lens 130, fourth lens 140, fifth lens 150, and sixth lens 160 are each made of glass material, thereby suppressing yellowing due to ultraviolet light and changes in optical properties due to temperature changes.

[0151] By satisfying condition (13), the imaging lens 10 can easily ensure the imaging range that an imaging device 1 used in, for example, an in-vehicle camera should satisfy.

[0152] By satisfying condition (14), the imaging lens 10 suppresses the occurrence of lateral chromatic aberration in the reverse direction, and axial chromatic aberration can also be easily corrected.

[0153] The imaging lens 10 can easily correct field curvature by satisfying condition (15), and axial chromatic aberration caused by the negative fifth lens 150 can also be easily corrected.

[0154] It will be apparent to those skilled in the art that this disclosure can be implemented in other predetermined forms besides the embodiments described above without deviating from its spirit or essential features. Therefore, the prior description is illustrative and not limiting. The scope of the disclosure is defined not by the prior description but by the added claims. Any modifications within their equivalent scope are included therein.

[0155] For example, the shape, size, arrangement, orientation, and number of each component described above are not limited to those shown in the above description and drawings. The shape, size, arrangement, orientation, and number of each component may be configured arbitrarily as long as they can achieve their function.

[0156] Although an imaging lens 10 according to one embodiment has been described, this disclosure is not limited to the imaging lens 10 of each embodiment described above, and various modifications are possible without departing from the spirit of the invention. For example, the specifications of the imaging lens 10 of each embodiment are illustrative, and various parameters can be changed within the scope of this disclosure. [Explanation of symbols]

[0157] 1. Imaging device 10 imaging lenses 110 First Lens 120 Second lens 130 Third Lens 140 Fourth Lens 150 Fifth Lens 160 6th lens 170 Aperture diaphragm 180a 1st plate 180b 2nd plate 20 Image sensors 21 Image plane Ax optical axis Di inter-plane spacing Da Total Length Ri radius of curvature Si surface

Claims

1. It is an imaging lens, Starting from the object side, it consists of a first lens with negative refractive power, a second lens with negative refractive power, a third lens with positive refractive power, an aperture diaphragm, a fourth lens with positive refractive power, a fifth lens with negative refractive power, and a sixth lens with positive refractive power. If R1 is the radius of curvature of the object side of the first lens, R2 is the radius of curvature of the image side of the first lens, D1 is the on-axial thickness of the first lens, and f is the focal length of the imaging lens with respect to the d line, then the conditional equation is: 0.6<(R1+R2) / (R1-R2)<0.8 (1) 0.14<D1 / f (3) An imaging lens that satisfies the requirements.

2. The imaging lens according to claim 1, If the focal length of the second lens with respect to the d line is f2, then the conditional equation is, -3.8<f2 / f<-2 (4) An imaging lens that satisfies the requirements.

3. An imaging lens according to claim 1 or 2, Each of the two surfaces of the second lens is concave. Imaging lens.

4. An imaging lens according to claim 1 or 2, If D2 is the on-axis distance from the image side of the first lens to the object side of the second lens, then the conditional equation is: 0.36<D2 / f<0.6 (5) An imaging lens that satisfies the requirements.

5. An imaging lens according to claim 1 or 2, Conditional expression, -6.7<R1 / f<-4.4 (6) An imaging lens that satisfies the requirements.

6. An imaging lens according to claim 1 or 2, If the Abbe number of the third lens is ν3, then the conditional equation is, 4.7<ν3 / f<5.7 (7) An imaging lens that satisfies the requirements.

7. An imaging lens according to claim 1 or 2, If the refractive index of the first lens is N1, then the conditional equation is: N1 / f<0.34 (8) An imaging lens that satisfies the requirements.

8. An imaging lens according to claim 1 or 2, The object side of the first lens is concave. Imaging lens.

9. An imaging lens according to claim 1 or 2, If Da is the total length of the imaging lens along its axis, then the conditional equation is: Da / f<5.2 (9) An imaging lens that satisfies the requirements.

10. An 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 equation is, -1.5<f1 / f<-1.2 (10) An imaging lens that satisfies the requirements.

11. An 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 equation is, 1.6<f3 / f<3.1 (11) An imaging lens that satisfies the requirements.

12. An imaging lens according to claim 1 or 2, The fourth lens and the fifth lens are formed as a cemented lens. Imaging lens.

13. An imaging lens according to claim 1 or 2, Each of the six surfaces of the aforementioned sixth lens is aspherical. Imaging lens.

14. An 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 equation is, 1.45<f6 / f<1.8 (12) An imaging lens that satisfies the requirements.

15. An imaging lens according to claim 1 or 2, Each of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens is formed of glass material. Imaging lens.

16. An imaging lens according to claim 1 or 2, If W is the half-angle of view of the light ray incident at the highest image height position on the image plane, then the conditional equation is: 48 < W (13) An imaging lens that satisfies the requirements.

17. An 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 equation is, -2.0<f5 / f<-1.1 (14) An imaging lens that satisfies the requirements.

18. An 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 equation is, 1.2<f4 / f<1.8 (15) An imaging lens that satisfies the requirements.

19. The imaging lens consists of, in order from the object side, a first lens with negative refractive power, a second lens with negative refractive power, a third lens with positive refractive power, an aperture diaphragm, a fourth lens with positive refractive power, a fifth lens with negative refractive power, and a sixth lens with positive refractive power. An image sensor that converts an optical image formed through the aforementioned imaging lens into an electrical signal, Equipped with, If R1 is the radius of curvature of the object side of the first lens, R2 is the radius of curvature of the image side of the first lens, D1 is the on-axial thickness of the first lens, and f is the focal length of the imaging lens with respect to the d line, then the conditional equation is: 0.6<(R1+R2) / (R1-R2)<0.8 (16) 0.14<D1 / f (17) An imaging device that satisfies the following conditions.

Images