Imaging optical system and camera

Abstract

To provide an image capturing optical system which is well corrected for various aberrations.SOLUTION: An image capturing optical system provided herein comprises, in order from the object side to the image side, a first lens element L1 with negative power having a concave surface on the image side, a second lens element L2 with power, a third lens element L3 with positive power, a fourth lens element L4 with power, and a fifth lens element L5 with power, and satisfies the following conditional expressions: R11 / TTL<0.25, ThL1 / Thsum<0.15, where R11 represents a paraxial curvature radius of an object-side surface of the first lens element, TTL represents a total optical length, ThL1 represents an optical axial thickness of the first lens element, and Thsum represents a sum of optical axial thickness of all the lens elements.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an imaging optical system and a camera. [Background technology]

[0002] Patent Document 1 discloses an imaging optical system that is composed of, in order from the object side, a positive or negative first lens group G1, an aperture stop S, and a positive second lens group G2, in which the first lens group has a negative lens closest to the object side, and the negative lens closest to the object side in the first lens group has an aspherical surface on its object side that is convex toward the object side in a paraxial direction, has the largest paraxial curvature within its effective diameter, and includes an aspherical surface that includes, within the effective diameter, a portion whose curvature is equal to or less than half the paraxial curvature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 093377 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides an imaging optical system and a camera that can effectively correct various aberrations. [Means for solving the problem]

[0005] The imaging optical system in the present disclosure comprises, in order from the object side to the image side, a first lens element having negative power with its concave surface facing the image side, a second lens element having power, a third lens element having positive power, a fourth lens element having positive power, a fifth lens element having negative power, and a sixth lens element having positive power. The object side surface of the second lens element has a convex shape facing the image side. The second lens element and the third lens element are disposed on the optical axis with an air gap therebetween. The fourth lens element and the fifth lens element are cemented together.

[0006] And the following condition (1): (2) and (6) Satisfy. R11 / TTL < 0.25 (1) ThL1 / Thsum < 0.10 (2) 0.5 < Thsum / TTL ≦0.64 (6) where: R11: paraxial radius of curvature of the object side surface of the first lens element, TTL: optical total length, ThL1: thickness of the first lens element on the optical axis, Thsum: the sum of the thicknesses of all lens elements on the optical axis, is.

[0007] The imaging optical system in the present disclosure comprises, in order from the object side to the image side, a first lens element having negative power with its concave surface facing the image side, a second lens element having power, a third lens element having positive power, a fourth lens element having positive power, a fifth lens element having negative power, and a sixth lens element having positive power. The object side surface of the second lens element has a convex shape facing the image side. The second lens element and the third lens element are disposed on the optical axis with an air gap therebetween. The fourth lens element and the fifth lens element are cemented together. The image side surface of the sixth lens element has a convex shape facing the image side.

[0008] And the following conditions (1), (2), (3), and (6) are satisfied. R11 / TTL < 0.25 (1) ThL1 / Thsum < 0.10 (2) 35 < |vd_L4 - vd_L5| < 65···(3) 0.5 < Thsum / TTL < 0.75 (6) where: R11: paraxial radius of curvature of the object side surface of the first lens element, TTL: optical total length, ThL1: thickness of the first lens element on the optical axis, Thsum: the sum of the thicknesses of all lens elements on the optical axis, vd_L4: Abbe number at the d line of the fourth lens element, vd_L5: Abbe number at the d line of the fifth lens element, is.

[0009] The camera according to the present disclosure includes an imaging optical system and an imaging element that converts an optical image formed by the imaging optical system into an electrical image signal. The imaging optical system includes, in order from the object side to the image side, a first lens element having negative power with its concave surface facing the image side, a second lens element having power, a third lens element having positive power, a fourth lens element having positive power, a fifth lens element having negative power, and a sixth lens element having positive power. The object side surface of the second lens element has a convex shape facing the image side. The second lens element and the third lens element are disposed on the optical axis with an air gap therebetween. The fourth lens element and the fifth lens element are cemented together, and the following conditions (1), (2), and (6) are satisfied. R11 / TTL < 0.25 (1) ThL1 / Thsum < 0.10 (2) 0.5 < Thsum / TTL ≦0.64 (6) where: R11: paraxial radius of curvature of the object side surface of the first lens element, TTL: optical total length, ThL1: thickness of the first lens element on the optical axis, Thsum: the sum of the thicknesses of all lens elements on the optical axis, is.

[0010] The camera according to the present disclosure includes an imaging optical system and an imaging element that converts an optical image formed by the imaging optical system into an electrical image signal. The imaging optical system includes, in order from the object side to the image side, a first lens element having negative power with its concave surface facing the image side, a second lens element having power, a third lens element having positive power, a fourth lens element having positive power, a fifth lens element having negative power, and a sixth lens element having positive power. The object side surface of the second lens element has a convex shape facing the image side. The second lens element and the third lens element are disposed on the optical axis with an air gap therebetween. The fourth lens element and the fifth lens element are cemented together. The image side surface of the sixth lens element has a convex shape facing the image side. The following conditions (1), (2), (3), and (6) are satisfied: R11 / TTL < 0.25 (1) ThL1 / Thsum < 0.10 (2) 35 < |vd_L4 - vd_L5| < 65 (3) 0.5 < Thsum / TTL < 0.75 (6) where: R11: paraxial radius of curvature of the object side surface of the first lens element, TTL: optical total length, ThL1: thickness of the first lens element on the optical axis, Thsum: the sum of the thicknesses of all lens elements on the optical axis, vd_L4: Abbe number at the d line of the fourth lens element, vd_L5: Abbe number at the d line of the fifth lens element, is. [Effects of the Invention]

[0011] The present disclosure provides an imaging optical system that is bright and capable of effectively correcting various aberrations. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a lens arrangement diagram showing an infinity focused state of an imaging optical system according to a first embodiment (numerical example 1); [Figure 2] 1 is a longitudinal aberration diagram of the imaging optical system according to Numerical Example 1 in a state where the imaging optical system is focused at infinity. [Figure 3] FIG. 10 is a lens arrangement diagram showing an infinity focused state of an imaging optical system according to a second embodiment (Numerical Example 2). [Figure 4] 10A and 10B are longitudinal aberration diagrams of the imaging optical system according to Numerical Example 2 in a state of focusing at infinity. [Figure 5] FIG. 10 is a lens arrangement diagram showing an infinity focused state of an imaging optical system according to a third embodiment (Numerical Example 3). [Figure 6] FIG. 10 is a longitudinal aberration diagram of the imaging optical system according to Numerical Example 3 in a state of focusing at infinity. [Figure 7] FIG. 10 is a lens arrangement diagram showing an infinity focused state of an imaging optical system according to a fourth embodiment (numerical example 4); [Figure 8] FIG. 10 is a longitudinal aberration diagram of the imaging optical system according to Numerical Example 4 in a state where the imaging optical system is focused at infinity. [Figure 9]Schematic diagram of an in-vehicle camera equipped with an imaging optical system according to the first embodiment. [Figure 10] Schematic diagram of a car equipped with an on-board camera at the front of the vehicle [Figure 11] A schematic diagram of a car with an onboard camera mounted at the front of the vehicle, viewed from the interior of the car. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, more detailed description than necessary may be omitted. For example, detailed description of well-known matters or redundant description of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art.

[0014] The inventors have provided the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend for them to limit the subject matter described in the claims.

[0015] (Embodiments 1 to 4: Imaging Optical System) 1, 3, 5, and 7 are lens layout diagrams of imaging optical systems according to Embodiments 1 to 4, respectively. In each diagram, an asterisk * attached to a specific surface indicates that the surface is aspherical. In each diagram, the line drawn on the far right indicates the position of the image plane S. Note that the aspect ratio is consistent in each diagram.

[0016] (Embodiment 1) FIG. 1 shows an imaging optical system according to the first embodiment.

[0017] The imaging optical system according to the first embodiment includes, in order from the object side to the image side, a first lens element L1 having negative power, a second lens element L2 having positive power, an aperture stop A, a third lens element L3 having positive power, a fourth lens element L4 having positive power, a fifth lens element L5 having negative power, and a sixth lens element L6 having positive power. Note that the object side corresponds to the side of the first lens element L1, and the image side corresponds to the side of the image plane S.

[0018] Each lens element will now be described.

[0019] The first lens element L1 is a meniscus lens having a convex surface facing the object side, and has aspheric shapes on both sides in the optical axis direction.

[0020] The second lens element L2 is a meniscus lens having a convex surface facing the image side, and has aspheric shapes on both sides in the optical axis direction.

[0021] The third lens element L3 is a biconvex lens.

[0022] The fourth lens element L4 is a biconvex lens.

[0023] The fifth lens element L5 is a meniscus lens having a convex surface facing the image side.

[0024] The sixth lens element L6 is a biconvex lens.

[0025] The fourth lens element L4 and the fifth lens element L5 are cemented together with an adhesive or the like to form a cemented lens.

[0026] (Embodiment 2) FIG. 3 shows an imaging optical system according to the second embodiment.

[0027] The imaging optical system according to the second embodiment includes, in order from the object side to the image side, a first lens element L1 having negative power, a second lens element L2 having positive power, an aperture stop A, a third lens element L3 having positive power, a fourth lens element L4 having positive power, a fifth lens element L5 having negative power, and a sixth lens element L6 having positive power. Note that the object side corresponds to the side of the first lens element L1, and the image side corresponds to the side of the image plane S.

[0028] Each lens element will now be described.

[0029] The first lens element L1 is a meniscus lens having a convex surface facing the object side, and has aspheric shapes on both sides in the optical axis direction.

[0030] The second lens element L2 is a meniscus lens having a convex surface facing the image side, and has aspheric shapes on both sides in the optical axis direction.

[0031] The third lens element L3 is a biconvex lens.

[0032] The fourth lens element L4 is a biconvex lens.

[0033] The fifth lens element L5 is a meniscus lens having a convex surface facing the image side.

[0034] The sixth lens element L6 is a meniscus lens having a convex surface facing the image side.

[0035] The fourth lens element L4 and the fifth lens element L5 are cemented together with an adhesive or the like to form a cemented lens.

[0036] (Embodiment 3) FIG. 5 shows an imaging optical system according to the third embodiment.

[0037] The imaging optical system according to the third embodiment includes, in order from the object side to the image side, a first lens element L1 having negative power, a second lens element L2 having negative power, an aperture stop A, a third lens element L3 having positive power, a fourth lens element L4 having positive power, a fifth lens element L5 having negative power, and a sixth lens element L6 having positive power. Note that the object side corresponds to the side of the first lens element L1, and the image side corresponds to the side of the image plane S.

[0038] Each lens element will now be described.

[0039] The first lens element L1 is a meniscus lens having a convex surface facing the object side, and has aspheric shapes on both sides in the optical axis direction.

[0040] The second lens element L2 is a meniscus lens having a convex surface facing the image side, and has aspheric shapes on both sides in the optical axis direction.

[0041] The third lens element L3 is a biconvex lens having aspherical shapes on both sides in the optical axis direction.

[0042] The fourth lens element L4 is a biconvex lens.

[0043] The fifth lens element L5 is a biconcave lens.

[0044] The sixth lens element L6 is a biconvex lens.

[0045] The fourth lens element L4 and the fifth lens element L5 are cemented together with an adhesive or the like to form a cemented lens.

[0046] (Fourth embodiment) FIG. 7 shows an imaging optical system according to the fourth embodiment.

[0047] The imaging optical system according to the fourth embodiment includes, in order from the object side to the image side, a first lens element L1 having negative power, a second lens element L2 having negative power, a third lens element L3 having positive power, an aperture stop A, a fourth lens element L4 having positive power, a fifth lens element L5 having negative power, a sixth lens element having positive power, and a seventh lens element having negative power. Note that the object side corresponds to the side of the first lens element L1, and the image side corresponds to the side of the image plane S.

[0048] Each lens element will now be described.

[0049] The first lens element L1 is a meniscus lens having a convex surface facing the object side, and has aspheric shapes on both sides in the optical axis direction.

[0050] The second lens element L2 is a biconcave lens.

[0051] The third lens element L3 is a biconvex lens.

[0052] The fourth lens element L4 is a biconvex lens.

[0053] The fifth lens element L5 is a meniscus lens having a convex surface facing the image side.

[0054] The sixth lens element L6 is a biconvex lens.

[0055] The seventh lens element L7 is a meniscus lens having a convex surface facing the image side.

[0056] The fifth lens element L5 and the sixth lens element L6 are cemented together with an adhesive or the like.

[0057] (Conditions and Effects) Below, we will explain the conditions that are beneficial for an imaging optical system such as the imaging optical systems according to Embodiments 1 to 4 to satisfy. Note that, for the imaging optical system according to each embodiment, several beneficial conditions are defined, and the imaging optical system configuration that satisfies all of these several conditions is the most effective. However, by satisfying each individual condition, it is also possible to obtain an imaging optical system that exhibits the corresponding effect.

[0058] For example, like the imaging optical systems according to embodiments 1 to 4, the imaging optical system according to the present disclosure includes, in order from the object side to the image side, a first lens element having negative power with its concave surface facing the image side, a second lens element having power, a third lens element having positive power, a fourth lens element having power, and a fifth lens element having power.

[0059] It is desirable to satisfy the following conditions (1) and (2).

[0060] R11 / TTL < 0.25 (1) ThL1 / Thsum < 0.15 (2) where: R11: paraxial radius of curvature of the object side surface of the first lens element L1, TTL: optical total length, ThL1: thickness of the first lens element L1 on the optical axis, Thsum: the sum of the thicknesses of all lens elements on the optical axis, is.

[0061] Condition (1) sets forth a preferable range of the paraxial radius of curvature of the object-side surface of first lens element L1 relative to the total optical length (the distance from the object-side surface of first lens element L1 to the image plane on the optical axis).

[0062] If the upper limit of condition (1) is exceeded, it becomes impossible to effectively prevent ghost light reflected from the object-side surface of the first lens element L1 from entering the image plane, and the angular resolution near the optical axis decreases, making it impossible to display objects near the optical axis at a larger magnification than the periphery.

[0063] Condition (2) defines the ratio of the axial thickness of the first lens element L1 to the sum of the axial thicknesses of all lens elements that constitute the imaging optical system and that have substantial power.

[0064] If the upper limit of condition (2) is exceeded, the thickness of the first lens element L1 increases, making it difficult to achieve both the angular resolution near the optical axis and the size of the imaging optical system.

[0065] In this case, it is more preferable to satisfy either or both of the following conditions (1a) and (2a) within the scope of conditions (1) and (2).

[0066] R11 / TTL < 0.24 (1a) ThL1 / Thsum < 0.12 (2a) This further improves the above-mentioned effects.

[0067] Furthermore, it is even more preferable if, within the scope of conditions (1) and (2), one or both of the following conditions (1b) and (2b) are satisfied.

[0068] R11 / TTL < 0.23 (1b) ThL1 / Thsum < 0.10 (2b) This further improves the above-mentioned effects.

[0069] Furthermore, for example, in an imaging optical system, the fourth lens element L4 and the fifth lens element L5 are cemented together, the fourth lens element L4 has positive power, and the fifth lens element L5 has negative power, and it is desirable that the following condition (3) be satisfied.

[0070] 30 < |vd_L4 - vd_L5| < 65 (3) where: vd_L4: Abbe number at the d line of the fourth lens element L4, vd_L5: Abbe number at the d line of the fifth lens element L5, is.

[0071] Condition (3) is a condition for setting forth a preferable range of the difference between the Abbe number at the d-line of the fourth lens element L4 and the Abbe number at the d-line of the fifth lens element L5.

[0072] If the lower limit of the condition (3) is exceeded, it becomes difficult to correct chromatic aberration. Furthermore, when the upper limit of condition (3) is exceeded, the refractive index of the low-dispersion glass material is low, which increases the sensitivity to optical performance and makes stable manufacturing difficult.

[0073] In this case, it is more preferable to satisfy either or both of the following conditions (3a) and (3b) within the scope of condition (3).

[0074] This further improves the above-mentioned effects.

[0075] 35 < |vd_L4 - vd_L5|···(3a) |vd_L4 - vd_L5| < 63···(3b) Furthermore, it is even more preferable if, within the scope of condition (3), either one or both of the following conditions (3c) and (3d) are satisfied.

[0076] 40 < |vd_L4 - vd_L5| (3c) |vd_L4 - vd_L5| < 60···(3d) This further improves the above-mentioned effects.

[0077] In addition, it is desirable that the imaging optical system satisfy, for example, the following condition (4):

[0078] -7.0E-6 < Min(dn / dt) < 0.0E-6 (4) where: Min(dn / dt): the smaller of the refractive index temperature coefficients for the d line of the third lens element L3 and the fourth lens element L4 at temperatures of 20°C to 40°C, is.

[0079] Condition (4) is a condition for setting forth the range of the minimum value of the temperature coefficient of refractive index for the d-line of the third lens element L3 and the fourth lens element L4 at temperatures of 20°C to 40°C.

[0080] If the value is below the lower limit of the condition (4), the correction of the changes in the focus position and the angle of view due to the change in the ambient temperature will be excessive, making it difficult to ensure good imaging performance.

[0081] Furthermore, if the upper limit of condition (4) is exceeded, correction of changes in the focus position and angle of view due to changes in the ambient temperature will be insufficient, making it difficult to ensure good imaging performance.

[0082] In this case, it is more preferable to satisfy either or both of the following conditions (4a) and (4b) within the scope of condition (4).

[0083] -6.5E-6 < Min(dn / dt) ···(4a) Min(dn / dt) < -1.5E-6 ···(4b) This further improves the above-mentioned effects.

[0084] Furthermore, it is even more preferable if, within the scope of condition (4), one or both of the following conditions (4c) and (4d) are satisfied:

[0085] -6.0E-6 < Min(dn / dt) ···(4c) Min(dn / dt) < -2.6E-6 ···(4d) This further improves the above-mentioned effects.

[0086] In addition, it is desirable that the imaging optical system satisfy, for example, the following condition (5):

[0087] 45° < ω (5) where: ω: half angle of view of the imaging optical system, is.

[0088] The condition (5) defines the half angle of view of the imaging optical system. If the condition (5) is not satisfied, the angular resolution at the center of the optical axis becomes too high, making it difficult to detect surrounding objects. In this case, it is more preferable to satisfy the following condition (5a) within the scope of condition (5).

[0089] 50° < ω (5a) This further improves the above-mentioned effects.

[0090] Furthermore, it is more preferable if the following condition (5b) is satisfied within the scope of condition (5):

[0091] 55° < ω (5b) This further improves the above-mentioned effects.

[0092] In addition, it is desirable that the imaging optical system satisfy, for example, the following condition (6):

[0093] 0.4 < Thsum / TTL < 1.6 (6) Condition (6) specifies the sum of the thicknesses on the optical axis of all lens elements that constitute the imaging optical system and have substantial power relative to the total optical length of the imaging optical system (the distance from the object-side surface of the first lens element L1 on the optical axis to the image plane).

[0094] If the value is below the lower limit of the condition (6), the total lens thickness relative to the total optical length becomes small, making it difficult to reduce the size of the optical system.

[0095] Furthermore, if the upper limit of condition (6) is exceeded, the volume of the lens increases, making it difficult to achieve a compact size.

[0096] In this case, it is more preferable to satisfy either or both of the following conditions (6a) and (6b) within the scope of condition (6).

[0097] 0.5 < Thsum / TTL (6a) Thsum / TTL < 0.75 (6b) This further improves the above-mentioned effects.

[0098] Furthermore, it is more preferable if, within the scope of condition (6), either one or both of the following conditions (6c) and (6d) are satisfied:

[0099] 0.6 ≦ Thsum / TTL (6c) Thsum / TTL < 0.70 (6d) This further improves the above-mentioned effects.

[0100] In addition, it is desirable that the imaging optical system satisfy, for example, the following condition (7):

[0101] -5.0< (R12+R11) / (R12-R11) < -1.5...(7) where: R11: first lens element L1 object side paraxial radius of curvature at the surface, R12: first lens element L1 Image side paraxial radius of curvature at the surface, is.

[0102] Condition (7) sets forth the shape factor of the first lens element L1 in the imaging optical system.

[0103] If the value is equal to or less than the lower limit of condition (7), the radius of curvature of the object-side surface of the first lens element L1 becomes large relative to the radius of curvature of the image-side surface, making it difficult to effectively correct spherical aberration.

[0104] Furthermore, if the upper limit of condition (7) is exceeded, the radius of curvature of the object-side surface of first lens element L1 will become too small relative to the radius of curvature of the image-side surface, which may increase the difficulty of manufacturing first lens element L1, resulting in a decrease in yield and an increase in costs.

[0105] In this case, it is more preferable to satisfy either or both of the following conditions (7a) and (7b) within the scope of condition (7).

[0106] -4.5< (R12+R11) / (R12-R11) ···(7a) (R12+R11) / (R12-R11) < -2.0 (7b) This further improves the above-mentioned effects.

[0107] Furthermore, it is even more preferable if, within the scope of condition (7), either one or both of the following conditions (7c) and (7d) are satisfied:

[0108] -4.0< (R12+R11) / (R12-R11) (7c) (R12+R11) / (R12-R11) < -2.5...(7d) This further improves the above-mentioned effects.

[0109] (Embodiment 5: Camera) An in-vehicle camera will be taken as an example to describe a camera equipped with the imaging optical system according to embodiment 1. Note that in the in-vehicle camera, any one of the imaging optical systems according to embodiments 2 to 4 may be applied instead of the imaging optical system according to embodiment 1.

[0110] FIG. 9 is a schematic diagram of an in-vehicle camera equipped with the imaging optical system according to the first embodiment.

[0111] The vehicle-mounted camera 100 includes an imaging optical system 201 that forms an optical image of an object, and an imaging element 202 that converts the optical image formed by the imaging optical system 201 into an electrical image signal. The imaging element 202 is disposed at the position of an image plane S in the imaging optical system according to the first embodiment.

[0112] FIG. 10 is a schematic diagram of an automobile in which an on-board camera 100 is provided at a front position inside a vehicle 500. In FIG.

[0113] FIG. 11 is a schematic view of a vehicle 500 with an on-board camera 100 mounted at the front of the interior of the vehicle, viewed from the interior of the vehicle.

[0114] The vehicle-mounted camera 100 is installed in the vehicle 500 and is used as a sensing camera or a view camera. Images captured by the sensing camera are used to check the distance between the vehicle and other vehicles. Images captured by the view camera are displayed on a monitor inside the vehicle and are used by the driver to check the area in front of, behind, and to the sides of the vehicle.

[0115] The image signal obtained by the image sensor 202 is displayed on, for example, a display device 401, a display device 402, or a display device 403 located in the front of the interior of the vehicle 500. The image signal is also recorded in a memory as, for example, image data.

[0116] The display device 401 is, for example, an electronic rearview mirror.

[0117] The display device 402 and the display device 403 are, for example, display devices of a navigation system, a front panel, or the like.

[0118] As a result, the vehicle 500 can display an image of the area in front of the vehicle on the display device 401, the display device 402, etc., using the in-vehicle camera 100 having the imaging optical system 201. Therefore, passengers such as the driver can see the rear of the vehicle 500.

[0119] In this way, the imaging optical system according to the present disclosure is effective for both the lens systems of a sensing camera and a view camera.

[0120] As described above, the fifth embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate.

[0121] A lens element that has substantially no power may be added as appropriate to the single focal length systems of the first to fourth embodiments.

[0122] The aspherical shape of the lens element of the single focal length system of Embodiments 1 to 4 is not limited to being formed by polishing or molding. For example, it may be a so-called replica lens (hybrid lens) in which an aspherical coating is formed on the surface of a spherical lens.

[0123] Although an example in which the imaging optical system according to embodiments 1 to 4 of the present disclosure is applied to an in-vehicle camera that is a sensing camera or a view camera is shown as embodiment 10, the imaging optical system according to the present disclosure can of course also be applied to cameras mounted on smartphones and mobile phones, surveillance cameras in surveillance systems, web cameras, etc.

[0124] (Numerical example) Numerical examples that specifically implement the imaging optical systems according to Embodiments 1 to 4 are described below. In each numerical example, all lengths in the tables are in "mm" and all angles of view are in "°". The term "angle of view" in the tables refers to the horizontal half angle of view. In each numerical example, r is the radius of curvature, d is the surface spacing, nd is the refractive index for the d-line, νd (also written as vd) is the Abbe number for the d-line, and dn / dt is the refractive index temperature coefficient for the d-line at temperatures between 20°C and 40°C, all of which are expressed in exponential notation (E notation) according to JIS X 0210. In each numerical example, surfaces marked with an * are aspherical, and the aspherical shape is defined by the following formula:

[0125]

number

[0126] where: Z: The distance from a point on the aspheric surface at a height h from the optical axis to the tangent plane of the vertex of the aspheric surface. h: height from the optical axis, r: apex curvature radius, κ: conic constant, A n:nth-order aspheric coefficient is.

[0127] 2, 4, 6, and 8 are longitudinal aberration diagrams of the imaging optical systems according to Numerical Examples 1 to 4 in a state where the optical system is focused at infinity.

[0128] Each longitudinal aberration diagram shows, from top to bottom, spherical aberration (SA (mm)), astigmatism (AST (mm)), and distortion (DIS (%)).

[0129] In the spherical aberration diagram, the vertical axis represents the F-number (indicated by F in the diagram), the solid line represents the d-line characteristics, the short dashed line represents the F-line characteristics, and the long dashed line represents the C-line characteristics.

[0130] In the astigmatism diagram, the vertical axis represents the image height, the solid line represents the characteristics in the sagittal plane (indicated by s in the diagram), and the dashed line represents the characteristics in the meridional plane (indicated by m in the diagram). Note that ω (also written as w) represents the horizontal half angle of view.

[0131] In the distortion diagram, the vertical axis represents the image height, and ω (also written as w) represents the horizontal half angle of view.

[0132] Here, the solid distortion line shows the aberration when the ideal image height is Y=f·tan(ω) (Y is the image height, f is the focal length of the entire system).

[0133] (Numerical Example 1) The imaging optical system of Numerical Example 1 corresponds to the first embodiment shown in FIG.

[0134] (surface data) Surface number rd nd vd dn / dt object surface ∞ 1* 4.37540 1.32590 1.81055 41.1 5.7E-6 2* 2.25470 2.67190 3* -5.51910 3.40340 1.81055 41.1 5.7E-6 4* -5.92940 0.60980 5 (twist) ∞ 0.50050 6 24.03650 3.83090 1.61997 63.9 -2.9E-6 7 -8.96020 1.40710 8 26.15600 3.73590 1.61800 63.4 -2.2E-6 9 -6.17410 0.00500 1.56732 42.8 10 -6.17410 0.60000 1.92286 20.9 1.8E-6 11 -24.80890 0.30000 12 28.40770 2.80290 1.58913 61.3 3.7E-6 13 -14.72000 0.00000 14 ∞ BF Image plane ∞ (Aspheric surface) Page 1 K=-1.48365E-01, A4=-5.11309E-03, A6=-1.57488E-04, A8= 1.70729E-05 A10 = -5.38841E-07 Page 2 K=-2.49327E+00, A4= 1.12935E-02, A6=-2.12019E-03, A8= 2.29147E-04 A10 = -8.07885E-06 Page 3 K=-1.99929E-01, A4=-1.78686E-03, A6=-7.58569E-05, A8=-5.95402E-07 A10 = -8.54962E-07 Page 4 K= 0.00000E+00, A4=-1.08476E-04, A6=-4.76612E-06, A8= 2.43399E-07 A10 = -1.53701E-08 (Various items) Focal distance 4.8928 F-number 1.62724 Angle of view 64.0000 Image height 4.0337 Lens total length 25.9778 BF 4.78450 Entrance pupil position 4.5027 Exit pupil position -25.9692 Front principal point position 8.4736 Back principal point position 21.0848 (single lens data) Lens starting surface focal length 1 1 -7.9699 2 3 36.2638 3 6 11.0176 4 8 8.4558 5 10 -9.0466 6 12 16.8643 (Numerical Example 2) The imaging optical system of Numerical Example 2 corresponds to the second embodiment shown in FIG.

[0135] (surface data) Surface number rd nd vd dn / dt object surface ∞ 1* 5.86720 1.47000 1.80610 40.7 7.9E-6 2* 2.87630 2.94910 3* -5.39750 4.03810 1.80610 40.7 7.9E-6 4* -6.99470 -0.05280 5 (Aperture) ∞ 0.50000 6 16.85710 4.48110 1.59282 68.6 -5.7E-6 7 -7.47480 1.20910 8 17.64460 4.08780 1.59282 68.6 -5.7E-6 9 -5.73920 0.00500 1.56732 42.8 10 -5.73920 0.60000 1.92286 20.9 1.8E-6 11 -19.40340 0.00500 1.56732 42.8 12 -19.40340 1.44640 1.72916 54.7 3.4E-6 13 -12.53680 0.00000 14∞BF Image plane ∞ (aspheric data) Front page K= 2.42540E-01, A4=-3.72448E-03, A6= 3.64410E-07, A8= 4.29785E-06 A10=-1.43950E-07 2nd side K=-3.10503E+00, A4= 7.07333E-03, A6=-1.05225E-03, A8= 1.03201E-04 A10=-3.17322E-06 3rd page K= 1.05412E+00, A4=-8.04282E-04, A6= 6.37489E-05, A8= 5.83983E-06 A10=-5.99813E-08 Side 4 K= 0.00000E+00, A4= 2.22241E-04, A6= 2.22692E-05, A8= 2.07640E-07 A10= 8.22340E-08 (Various data) Focal length 4.8560 F-number 1.62802 Angle of view 60.0000 Image height 4.0341 Lens total length 25.9943 BF 5.25550 Entrance pupil position 4.6104 Exit pupil position -19.5693 Front principal point position 8.2614 Back principal point position 21.1383 (single lens data) Lens starting surface focal length 1 1 -8.9665 2 3 228.3666 3 6 9.3782 4 8 7.8134 5 10 -9.0211 6 12 44.6213 (Numerical Example 3) The imaging optical system of Numerical Example 3 corresponds to the third embodiment shown in FIG.

[0136] (surface data) Surface number rd nd vd dn / dt object surface ∞ 1* 4.87820 1.47000 1.80610 40.7 7.9E-6 2* 2.56320 3.45190 3* -5.64550 4.12020 1.80610 40.7 7.9E-6 4* -7.84880 -0.15830 5 (Aperture) ∞ 0.52140 6* 10.61360 5.10000 1.59201 67.0 -7.0E-7 7* -8.45120 1.00540 8 16.61910 3.63510 1.59282 68.6 -5.7E-6 9 -8.37910 0.00500 1.56732 42.8 10 -8.37910 0.60000 1.92286 20.9 1.8E-6 11 81.84740 0.00500 1.56732 42.8 12 81.84740 2.07090 1.72916 54.7 3.4E-6 13 -14.72950 0.00000 14∞BF Image plane ∞ (aspheric data) Front page K=-2.20991E-01, A4=-3.20613E-03, A6=-4.86262E-05, A8= 4.01742E-06 A10=-1.02311E-07 2nd side K=-1.08793E+00, A4=-1.75021E-03, A6=-7.98643E-05, A8= 1.86439E-05 A10=-7.93577E-07 3rd page K=-1.49116E+00, A4=-1.89421E-03, A6=-3.72248E-05, A8=-1.35022E-06 A10=-3.66396E-07 Side 4 K= 0.00000E+00, A4=-1.22533E-05, A6= 2.33327E-05, A8=-5.23830E-07 A10= 5.18589E-09 Page 6 K= 0.00000E+00, A4=-5.51506E-05, A6= 3.45380E-05, A8=-1.17086E-06 A10= 3.36727E-08 Side 7 K= 0.00000E+00, A4= 3.98597E-04, A6= 1.67138E-05, A8=-2.99422E-07 A10= 4.08178E-08 (Various data) Focal length 4.8547 F-number 1.45814 Angle of view 60.0000 Image height 4.0347 Lens length 26.6775 BF 4.85090 Entrance pupil position 5.1079 Exit pupil position -19.7548 Front principal point position 8.7696 Back principal point position 21.8230 (single lens data) Lens starting surface focal length 1 1 -9.3504 2 3 -150.8604 3 6 8.8251 4 8 9.9342 5 10 -8.2101 6 12 17.2759 (Numerical Example 4) The imaging optical system of Numerical Example 4 corresponds to the fourth embodiment shown in FIG.

[0137] Surface number rd nd vd dn / dt object surface ∞ 1* 4.85780 1.69660 1.81055 41.1 5.7E-6 2* 2.68620 3.10610 3 -27.93060 0.60920 1.70154 41.2 4.4E-6 4 8.50980 1.16450 5 10.32430 4.12780 1.95375 32.3 4.4E-6 6 -17.15780 2.35350 7 (Aperture) ∞ 0.23710 8 71.00550 4.45560 1.59282 68.6 -5.7E-6 9 -4.45850 0.00500 1.56732 42.8 10 -4.45850 0.65850 1.92286 20.9 1.8E-6 11 -8.94710 0.53170 12 9.83820 4.99910 1.80420 46.5 4.1E-6 13 -17.36890 1.24380 14 -10.68750 2.20950 1.80518 25.5 9.0E-7 15 -69.28910 0.00000 16∞BF Image plane ∞ (aspheric data) Front page K=-4.60947E-01, A4=-1.94353E-03, A6=-1.08387E-04, A8= 4.91796E-06 A10=-9.02563E-08, A12= 4.53987E-10 2nd side K=-9.90859E-01, A4=-1.56624E-03, A6=-2.34822E-04, A8= 1.77182E-05 A10=-3.45447E-07, A12= 0.00000E+00 (Various data) Focal length 5.3190 F-number 1.44038 Angle of view 62.0000 Image height 4.0359 Lens length 29.8657 BF 2.46770 Entrance pupil position 7.3155 Exit pupil position -12.6919 Front principal point position 10.4054 Back principal point position 24.5467 (single lens data) Lens starting surface focal length 1 1 -11.4010 2 3 -9.2339 3 5 7.2931 4 8 7.2354 5 10 -10.3594 6 12 8.5065 7 14 -15.9626 (Condition's corresponding value) The following table shows the corresponding values ​​for each numerical example.

[0138] [Table 1]

[0139] As described above, the embodiments have been described as examples of the technology in the present disclosure, and for that purpose, the accompanying drawings and detailed description have been provided.

[0140] Therefore, the components shown in the accompanying drawings and detailed description may include not only essential components for solving the problem, but also components that are not essential for solving the problem in order to illustrate the above technology. Therefore, the fact that these non-essential components are shown in the accompanying drawings or detailed description should not be interpreted as immediately indicating that these non-essential components are essential.

[0141] Furthermore, since the above-described embodiments are intended to illustrate the technology of the present disclosure, various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0142] The present disclosure is applicable to imaging optical systems used in vehicle-mounted cameras, surveillance cameras, web cameras, etc. The present disclosure is particularly useful in imaging optical systems used in cameras that require high image quality, such as vehicle-mounted cameras. [Explanation of symbols]

[0143] L1 First lens element L2 Second lens element L3 Third lens element L4 Fourth lens element L5 Fifth lens element L6 Sixth lens element L7 Seventh lens element A aperture stop S image plane 100 in-car cameras 201 Imaging Optical System 202 Image sensor 401 Display device 402 Display device 403 Display device 500 vehicles

Claims

1. From the object side to the image side, a first lens element having a negative power and a concave surface facing the image side; a second lens element having power; and a third lens element having positive power; and a fourth lens element having positive power; and a fifth lens element having negative power; and a sixth lens element having positive power; and Equipped with the object side surface of the second lens element has a convex shape toward the image side, the second lens element and the third lens element are disposed on an optical axis with an air gap therebetween, the fourth lens element and the fifth lens element are cemented together; The following conditions (1), (2), and (6) are satisfied: R11 / TTL < 0.25...(1) ThL1 / Thsum < 0.10...(2) 0.5 < Thsum / TTL ≦0.64 (6) where: R11: paraxial radius of curvature of the object side surface of the first lens element, TTL: optical total length, ThL1: the thickness of the first lens element on the optical axis, Thsum: the sum of the thicknesses of all lens elements on the optical axis, That is, Imaging optical system.

2. The following condition (3) is satisfied: 30 < |vd_L4 - vd_L5 | < 65...(3) where: vd_L4: Abbe number at the d-line of the fourth lens element, vd_L5: Abbe number at the d-line of the fifth lens element, That is, The imaging optical system according to claim 1 .

3. From the object side to the image side, a first lens element having a negative power and a concave surface facing the image side; a second lens element having power; and a third lens element having positive power; and a fourth lens element having positive power; and a fifth lens element having negative power; and a sixth lens element having positive power; and Equipped with the object side surface of the second lens element has a convex shape toward the image side, the second lens element and the third lens element are disposed on an optical axis with an air gap therebetween, the fourth lens element and the fifth lens element are cemented together; an image side surface of the sixth lens element having a convex shape toward the image side; The following conditions (1), (2), (3), and (6) are satisfied: R11 / TTL < 0.25...(1) ThL1 / Thsum < 0.10...(2) 35 < |vd_L4 - vd_L5 | < 65...(3) 0.5<Thsum / TTL<0.75...(6) where: R11: paraxial radius of curvature of the object side surface of the first lens element, TTL: optical total length, ThL1: the thickness of the first lens element on the optical axis, Thsum: the sum of the thicknesses of all lens elements on the optical axis, vd_L4: Abbe number at the d-line of the fourth lens element, vd_L5: Abbe number at the d-line of the fifth lens element, That is, Imaging optical system.

4. The following condition (4) is satisfied: -7.0E-6 < Min (dn / dt) < 0.0E-6...(4) where: Min(dn / dt): the smaller of the refractive index temperature coefficients of the third lens element and the fourth lens element for the d line at a temperature of 20°C to 40°C, That is, The imaging optical system according to claim 1 .

5. The following condition (5) is satisfied: 45° < ω...(5) where: ω: half angle of view of the imaging optical system, That is, The imaging optical system according to claim 1 .

6. The following condition (7) is satisfied: -5.0<(R12+R11) / (R12-R11)<-1.5...(7) where: R11: paraxial radius of curvature of the object side surface of the first lens element, R12: paraxial radius of curvature of the image side surface of the first lens element, That is, The imaging optical system according to claim 1 .

7. an imaging optical system according to any one of claims 1 to 6, which forms an optical image of an object; an imaging element that converts an optical image formed by the imaging optical system into an electrical image signal; A camera.

Images