imaging optical lens

Abstract

The present invention relates to the technical field of optical lenses. Disclosed is an imaging optical lens comprising a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having positive refractive power, a fifth lens having positive refractive power, and a sixth lens having negative refractive power, arranged in order from the object side toward the imaging side, wherein the on-axis distance from the imaging side of the first lens to the object side of the second lens is d2, the total optical length of the imaging optical lens is TTL, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the central radius of curvature of the object side of the fourth lens is R7, the central radius of curvature of the imaging side of the fourth lens is R8, and the relationship expressed as 0.10≦d2 / TTL≦0.20, 0.60≦f3 / f4≦1.40, and 0.01≦R7 / R8≦0.30.

Description

[Technical Field]

[0001] The present invention relates to the field of optical lenses, and more particularly to imaging optical lenses suitable for portable terminal equipment such as smartphones and digital cameras, and imaging optical lenses suitable for imaging devices such as surveillance cameras, PC lenses, and in-vehicle lenses. [Background technology]

[0002] In recent years, with the emergence of various smart devices, the need for miniaturized imaging optical lenses has been steadily increasing. Furthermore, in addition to the reduction in pixel size of photodetectors, the development trend towards high-performance, thin, lightweight, and portable electronic products has led to miniaturized imaging optical lenses with good image quality becoming mainstream in the market. To achieve superior image quality, multi-lens structures are often used. However, with technological advancements and the increasing diversification of user needs, the pixel area of ​​photodetectors is shrinking, and the demand for system image quality continues to rise, leading to the emergence of six-lens structures in lens design. There is a pressing need for imaging optical lenses with superior optical properties. [Overview of the Initiative]

[0003] In view of the above-mentioned problems, the present invention aims to provide an imaging optical lens having good optical performance.

[0004] To solve the above technical problems, according to an embodiment of the present invention, an imaging optical lens is provided which includes a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having positive refractive power, a fifth lens having positive refractive power, and a sixth lens having negative refractive power, arranged in order from the object side toward the image-forming side, The optical axis distance from the image-forming side of the first lens to the object-facing side of the second lens is d2, the total optical length of the imaging optical lens is TTL, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the central radius of curvature of the object-facing side of the fourth lens is R7, and the central radius of curvature of the image-forming side of the fourth lens is R8. 0.10 ≤ d² / TTL ≤ 0.20 0.60 ≤ f3 / f4 ≤ 1.40 0.01 ≤ R7 / R8 ≤ 0.30 An imaging optical lens that satisfies the relationship expressed in the above equation is provided.

[0005] Preferably, the central radius of curvature of the object side surface of the first lens is R1, the central radius of curvature of the image-forming side surface of the first lens is R2, and the relationship expressed as 1.80 ≤ (R1 + R2) / (R1 - R2) ≤ 6.30 is satisfied.

[0006] Preferably, the fifth lens is provided bonded to the sixth lens.

[0007] Preferably, the Abbe number of the fifth lens is V5, the Abbe number of the sixth lens is V6, and the relationship expressed as V5-V6≧35.00 is satisfied.

[0008] Preferably, the focal length of the imaging optical lens is f, and the relationship expressed as 5.00 ≤ TTL / f ≤ 7.00 is satisfied.

[0009] Preferably, the portion of the first lens near the optical axis on the object side is convex, the portion of the first lens near the optical axis on the image-forming side is concave, the focal length of the imaging optical lens is f, the focal length of the first lens is f1, and the thickness of the first lens on the optical axis is d1. -6.21 ≤ f1 / f ≤ -0.97 0.01 ≤ d1 / TTL ≤ 0.10 The relationship expressed above is satisfied.

[0010] Preferably, the portion of the second lens near the optical axis on the object side is concave, the portion of the second lens near the optical axis on the image-forming side is convex, the focal length of the imaging optical lens is f, the focal length of the second lens is f2, the central radius of curvature of the object side of the second lens is R3, the central radius of curvature of the image-forming side of the second lens is R4, and the thickness of the second lens on the optical axis is d3. -21.11 ≤ f² / f ≤ -3.75 -9.81≦(R3+R4) / (R3-R4)≦-2.45 0.06 ≤ d3 / TTL ≤ 0.26 The relationship expressed above is satisfied.

[0011] Preferably, the portion of the third lens near the optical axis on the object side is convex, the portion of the third lens near the optical axis on the image-forming side is convex, the focal length of the imaging optical lens is f, the central radius of curvature of the object side of the third lens is R5, the central radius of curvature of the image-forming side of the third lens is R6, and the thickness of the third lens on the optical axis is d5. 1.18 ≤ f³ / f ≤ 5.80 -1.96≦(R5+R6) / (R5-R6)≦-0.31 0.02 ≤ d5 / TTL ≤ 0.26 The relationship expressed above is satisfied.

[0012] Preferably, the portion of the fourth lens near the optical axis on the object side is convex, the portion of the fourth lens near the optical axis on the image-forming side is concave, the focal length of the imaging optical lens is f, and the on-axis thickness of the fourth lens is d7. 1.29 ≤ f₄ / f ≤ 5.84 -3.71≦(R7+R8) / (R7-R8)≦-0.68 0.07 ≤ d7 / TTL ≤ 0.26 The relationship expressed above is satisfied.

[0013] Preferably, a portion of the fifth lens near the optical axis on the object side surface is a convex surface, a portion of the fifth lens near the optical axis on the imaging side surface is a convex surface, the focal length of the imaging optical lens is f, the focal length of the fifth lens is f5, the central radius of curvature of the object side surface of the fifth lens is R9, the central radius of curvature of the imaging side surface of the fifth lens is R10, and the thickness of the fifth lens on the optical axis is d9. 0.56 ≦ f5 / f ≦ 2.34 0.13 ≦ (R9 + R10) / (R9 - R10) ≦ 0.50 0.05 ≦ d9 / TTL ≦ 0.18 It satisfies the relational expression represented by the above formula.

[0014] Preferably, a portion of the sixth lens near the optical axis on the object side surface is a concave surface, a portion of the sixth lens near the optical axis on the imaging side surface is a convex surface, the focal length of the imaging optical lens is f, the focal length of the sixth lens is f6, the central radius of curvature of the object side surface of the sixth lens is R11, the central radius of curvature of the imaging side surface of the sixth lens is R12, and the thickness of the sixth lens on the optical axis is d11. -​​4.36 ≦ f6 / f ≦ -​​0.83 -​​3.71 ≦ (R11 + R12) / (R11 - R12) ≦ -​​0.72 0.03 ≦ d11 / TTL ≦ 0.13 It satisfies the relational expression represented by the above formula.

[0015] Preferably, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all made of glass.

Advantages of the Invention

[0016] The beneficial effects of the present invention are as follows. The imaging optical lens of the present invention has excellent optical characteristics and good optical performance, and is particularly applicable to in-vehicle lenses and WEB imaging lenses composed of imaging elements such as CCDs and CMOSs for high-pixel use.

Brief Description of the Drawings

[0017] To more clearly explain the technical concepts in the embodiments of the present invention, the drawings necessary for describing the embodiments will be briefly described below. Clearly, the drawings described below represent only a few embodiments of the present invention, and those skilled in the art can obtain other drawings based on these without inventive effort.

[0018] [Figure 1] Figure 1 shows the structure of an imaging optical lens according to a first embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram of the axial chromatic aberration of the imaging optical lens shown in Figure 1. [Figure 3] Figure 3 shows the chromatic aberration of the imaging optical lens shown in Figure 1. [Figure 4] Figure 4 shows the field curvature and distortion of the imaging optical lens shown in Figure 1. [Figure 5] Figure 5 shows the structure of an imaging optical lens according to a second embodiment of the present invention. [Figure 6] Figure 6 is a schematic diagram of the axial chromatic aberration of the imaging optical lens shown in Figure 5. [Figure 7] Figure 7 shows the chromatic aberration of the imaging optical lens shown in Figure 5. [Figure 8] Figure 8 shows the field curvature and distortion of the imaging optical lens shown in Figure 5. [Figure 9] Figure 9 shows the structure of an imaging optical lens according to the third embodiment of the present invention. [Figure 10] Figure 10 shows the axial chromatic aberration of the imaging optical lens shown in Figure 9. [Figure 11] Figure 11 shows the chromatic aberration of the imaging optical lens shown in Figure 9. [Figure 12] Figure 12 shows the field curvature and distortion of the imaging optical lens shown in Figure 9. [Figure 13] Figure 13 shows the structure of an imaging optical lens according to a fourth embodiment of the present invention. [Figure 14]Figure 14 shows the axial chromatic aberration of the imaging optical lens shown in Figure 13. [Figure 15] Figure 15 shows the chromatic aberration of the imaging optical lens shown in Figure 13. [Figure 16] Figure 16 shows the field curvature and distortion of the imaging optical lens shown in Figure 13. [Figure 17] Figure 17 shows the structure of an imaging optical lens according to a fifth embodiment of the present invention. [Figure 18] Figure 18 shows the axial chromatic aberration of the imaging optical lens shown in Figure 17. [Figure 19] Figure 19 shows the chromatic aberration of the imaging optical lens shown in Figure 17. [Figure 20] Figure 20 shows the field curvature and distortion of the imaging optical lens shown in Figure 17. [Figure 21] Figure 21 shows the structure of an imaging optical lens according to the sixth embodiment of the present invention. [Figure 22] Figure 22 shows the axial chromatic aberration of the imaging optical lens shown in Figure 21. [Figure 23] Figure 23 shows the chromatic aberration of the imaging optical lens shown in Figure 21. [Figure 24] Figure 24 shows the field curvature and distortion of the imaging optical lens shown in Figure 21. [Figure 25] Figure 25 shows the structure of an imaging optical lens according to a comparative embodiment of the present invention. [Figure 26] Figure 26 shows the axial chromatic aberration of the imaging optical lens shown in Figure 25. [Figure 27] Figure 27 shows the chromatic aberration of the imaging optical lens shown in Figure 25. [Figure 28] Figure 28 shows the field curvature and distortion of the imaging optical lens shown in Figure 25. [Modes for carrying out the invention]

[0019] To further clarify the object, technical features, and advantages of the present invention, each embodiment of the present invention will be described in detail below with reference to the drawings. However, although many technical details are described in each embodiment of the present invention for the convenience of understanding the invention, it will be obvious to those skilled in the art that the technical features to be protected by the present invention can be realized without these technical details and the various changes and modifications based on the following embodiments.

[0020] As shown in the drawings, the present invention provides imaging optical lenses 10, 20, 30, 40, 50, and 60. Figures 1, 5, 9, 13, 17, and 21 show imaging optical lenses 10, 20, 30, 40, 50, and 60 according to the present invention. The imaging optical lenses 10, 20, 30, 40, 50, and 60 include six lenses. Specifically, the imaging optical lenses 10, 20, 30, 40, 50, and 60 include, in order from the object side to the image side, a first lens L1, a second lens L2, an aperture S1, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6. An optical element such as an optical filter GF may be installed between the sixth lens L6 and the image plane Si.

[0021] The first lens L1 has a negative refractive power, the second lens L2 has a negative refractive power, the third lens L3 has a positive refractive power, the fourth lens L4 has a positive refractive power, the fifth lens L5 has a positive refractive power, and the sixth lens L6 has a negative refractive power. In other embodiments, each lens may have a different refractive power.

[0022] When d2 is the optical axial distance from the imaging side of the first lens L1 to the object side of the second lens L2, and TTL is the total optical length of the imaging optical lens, the relationship expressed as 0.10 ≤ d2 / TTL ≤ 0.20 is satisfied. This relationship defines the ratio of the distance between the first lens L1 and the second lens L2 to the total optical length. Within the range of this relationship, a value higher than the lower limit is advantageous for the smooth transition of light rays near the aperture, and allows for an effective balance of the field curvature of the imaging optical lens, thereby reducing the shift amount of field curvature in the central field of view to less than 0.01 mm. By keeping d2 / TTL below the upper limit, the total optical length of the imaging optical lens can be controlled.

[0023] The focal length of the third lens L3 is f3, and the focal length of the fourth lens L4 is f4, satisfying the relationship expressed as 0.60 ≤ f3 / f4 ≤ 1.40. This relationship defines the ratio of the focal lengths of the third lens L3 and the fourth lens L4. The closer the focal lengths of the two lenses described above are, the more favorable it is for the smooth transition of light rays, and the better the image mass can be improved.

[0024] The central radius of curvature of the object side surface of the fourth lens L4 is R7, and the central radius of curvature of the image-forming side surface of the fourth lens L4 is R8, satisfying the relationship expressed as 0.01 ≤ R7 / R8 ≤ 0.30. This relationship defines the shape of the fourth lens L4. Within the range of this relationship, the degree of polarization when light rays pass through the lens can be mitigated, and the imaging optical lens can have excellent image-forming quality and low sensitivity.

[0025] When the above-mentioned relationships are satisfied, the imaging optical lenses 10, 20, 30, 40, 50, and 60 have good optical performance and can meet the design requirements for large aperture and wide angle of view. Based on the characteristics of the imaging optical lenses 10, 20, 30, 40, 50, and 60, these imaging optical lenses are particularly applicable to automotive lenses composed of image sensors such as CCDs and CMOS sensors for high pixel counts, as well as to web imaging lenses.

[0026] Based on the relationships and achievable functions described above, the characteristics of each lens will be explained in detail.

[0027] In this embodiment, the first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, and sixth lens L6 are all made of glass. By appropriately selecting glass lenses, the optical performance of the imaging optical lens can be improved. In other embodiments, each lens may be made of a different material.

[0028] The first lens L1 is an aspherical lens, the second lens L2 is a spherical lens, the third lens L3 is a spherical lens, the fourth lens L4 is an aspherical lens, the fifth lens L5 is a spherical lens, and the sixth lens L6 is a spherical lens.

[0029] When R1 is the central radius of curvature of the object-side surface of the first lens L1, and R2 is the central radius of curvature of the image-forming side surface of the first lens L1, the relationship expressed as 1.80 ≤ (R1 + R2) / (R1 - R2) ≤ 6.30 is satisfied. This relationship defines the shape of the first lens L1. Within the range of this relationship, the degree of polarization when light rays pass through the lens can be mitigated, effectively improving aberrations and enhancing image quality.

[0030] The fifth lens L5 is bonded to the sixth lens. By bonding them together, the overall volume of the imaging optical lens is reduced, and by forming the two lenses as a single integrated structure, the two lenses can be attached in a single step when assembling the optical module.

[0031] When the Abbe number of the fifth lens L5 is v5 and the Abbe number of the sixth lens L6 is v6, the relationship v5-v6≧35.00 is satisfied. This relationship specifies the difference in Abbe numbers between the fifth lens L5 and the sixth lens L6, which are bonded together. Within the range of this relationship, material attributes can be effectively distributed, chromatic aberration can be effectively eliminated, and chromatic aberration can be reduced to |LC|≦8μm.

[0032] When the focal length of the imaging optical lens 10 is f, the relationship expressed as 5.00 ≤ TTL / f ≤ 7.00 is satisfied. This relationship defines the telephoto ratio. By keeping TTL / f below the upper limit, the reduction in the overall optical length can be controlled, making it easier to miniaturize the imaging optical lens. On the other hand, by keeping TTL / f above the lower limit of the above relationship, distortion and chromatic aberration on the optical axis can be easily corrected, and good optical performance of the imaging optical lens can be maintained.

[0033] In this embodiment, the portion of the first lens L1 closest to the optical axis on the object side is convex, and the portion of the image-forming side closest to the optical axis is concave. In other embodiments, the object side and image-forming side of the first lens L1 may be provided with other concave-convex distributions.

[0034] When the focal length of the first lens is f1, the relationship expressed as -6.21 ≤ f1 / f ≤ -0.97 is satisfied. This relationship defines the ratio of the focal length f1 of the first lens L1 to the focal length f of the imaging optical lens 10. Within the range of this relationship, an ultra-wide angle of view can be achieved. It is preferable that -3.88 ≤ f1 / f ≤ -1.22 is satisfied.

[0035] When the thickness of the first lens L1 along the optical axis is d1, the relation expressed as 0.01 ≤ d1 / TTL ≤ 0.10 is satisfied. Within the range of this relation, miniaturization can be achieved. It is preferable that 0.02 ≤ d1 / TTL ≤ 0.08 is satisfied.

[0036] In this embodiment, the portion of the second lens L2 closest to the optical axis on the object side is concave, and the portion of the image-forming side closest to the optical axis is convex. In other embodiments, the object side and image-forming side of the second lens L2 may be provided with other concave-convex distributions.

[0037] In this embodiment, when the focal length of the second lens L2 is f2, the relationship expressed as -21.11 ≤ f2 / f ≤ -3.75 is satisfied. This relationship defines the ratio of the focal length f2 of the second lens L2 to the focal length of the imaging optical lens 10. Within the range of this relationship, the amount of field curvature of the system (i.e., the imaging optical lens) can be effectively balanced. It is preferable that -13.19 ≤ f2 / f ≤ -4.69 is satisfied.

[0038] The central radius of curvature of the object side surface of the second lens L2 is R3, and the central radius of curvature of the image-forming side surface of the second lens L2 is R4, satisfying the relationship expressed as -9.81 ≤ (R3 + R4) / (R3 - R4) ≤ -2.45. This relationship defines the shape of the second lens L2. Within the range of this relationship, problems such as axial chromatic aberration associated with widening the field of view of the imaging optical lens can be effectively corrected. It is preferable that -6.13 ≤ (R3 + R4) / (R3 - R4) ≤ -3.06 is satisfied.

[0039] The on-axis thickness of the second lens L2 is d3, and it satisfies the relationship expressed as 0.06 ≤ d3 / TTL ≤ 0.26. Miniaturization can be achieved within the range of this relationship. It is preferable that 0.10 ≤ d3 / TTL ≤ 0.21 is satisfied.

[0040] The portion of the third lens L3 closest to the optical axis on the object side is convex, and the portion of the image-forming side closest to the optical axis is also convex. In other embodiments, the object side and the image-forming side of the third lens L3 may be provided with other concave-convex distributions.

[0041] The imaging optical lens 10 satisfies the relationship expressed as 1.18 ≤ f3 / f ≤ 5.80. When f3 / f satisfies the above relationship, temperature drift can be controlled and better temperature performance can be achieved by controlling the focal length value of the single lens and appropriately distributing the focal length. It is preferable that 1.89 ≤ f3 / f ≤ 4.64 is satisfied.

[0042] The central radius of curvature of the object side of the third lens L3 is R5, and the central radius of curvature of the image-forming side of the third lens L3 is R6, satisfying the relationship -1.96 ≤ (R5 + R6) / (R5 - R6) ≤ -0.31. This relationship defines the shape of the third lens L3. Within the range of this relationship, the degree of light ray polarization can be reduced, and chromatic aberration can be effectively improved. It is preferable that -1.22 ≤ (R5 + R6) / (R5 - R6) ≤ -0.38 is satisfied.

[0043] The on-axis thickness of the third lens L3 is d5, and it satisfies the relationship expressed as 0.02 ≤ d5 / TTL ≤ 0.26. Miniaturization can be achieved within the range of this relationship. It is preferable that 0.04 ≤ d5 / TTL ≤ 0.20 is satisfied.

[0044] In this embodiment, the portion of the fourth lens L4 closest to the optical axis on the object side is convex, and the portion of the image-forming side closest to the optical axis is concave. In other embodiments, the object side and image-forming side of the fourth lens L4 may be provided with other concave-convex distributions.

[0045] The imaging optical lens 10 further satisfies the relationship expressed as 1.29 ≤ f4 / f ≤ 5.84. By appropriately distributing the optical power, the imaging optical lens can have excellent image quality and low sensitivity. It is preferable that 2.06 ≤ f4 / f ≤ 4.67 is satisfied.

[0046] The central radius of curvature of the object side of the fourth lens L4 is R7, and the central radius of curvature of the image-forming side of the fourth lens L4 is R8, further satisfying the relationship expressed as -3.71 ≤ (R7 + R8) / (R7 - R8) ≤ -0.68. This relationship defines the shape of the fourth lens L4. Within the range of this relationship, aberrations of the off-axis angle of view can be effectively corrected as the focal length increases. It is preferable that -2.32 ≤ (R7 + R8) / (R7 - R8) ≤ -0.85 is satisfied.

[0047] The on-axis thickness of the fourth lens L4 is d7, and it further satisfies the relationship expressed as 0.07 ≤ d7 / TTL ≤ 0.26. Miniaturization can be achieved within the range of this relationship. It is preferable that 0.11 ≤ d7 / TTL ≤ 0.21 is satisfied.

[0048] In this embodiment, the portion of the fifth lens L5 closest to the optical axis on the object side is convex, and the portion of the image-forming side closest to the optical axis is also convex. In other embodiments, the object side and the image-forming side of the fifth lens L5 may be provided with other concave-convex distributions.

[0049] The focal length of the fifth lens L5 is f5, and it further satisfies the relationship expressed as 0.56 ≤ f5 / f ≤ 2.34. By appropriately distributing the optical power, the imaging optical lens can have excellent image quality and low sensitivity. It is preferable that 0.89 ≤ f5 / f ≤ 1.87 is satisfied.

[0050] The central radius of curvature of the side surface of the fifth lens L5 is R9, and the central radius of curvature of the image-forming side surface of the fifth lens L5 is R10, further satisfying the relationship expressed as 0.13 ≤ (R9 + R10) / (R9 - R10) ≤ 0.50. This relationship defines the shape of the fifth lens L5. Within the range of this relationship, aberrations of the off-axis angle of view can be effectively corrected as wide-angle lenses advance. It is preferable that 0.21 ≤ (R9 + R10) / (R9 - R10) ≤ 0.40 is satisfied.

[0051] The on-axis thickness of the fifth lens L5 is d9, and it further satisfies the relationship expressed as 0.05 ≤ d9 / TTL ≤ 0.18. Miniaturization can be achieved within the range of this relationship. It is preferable that 0.08 ≤ d9 / TTL ≤ 0.14 is satisfied.

[0052] In this embodiment, the portion of the sixth lens L6 closest to the optical axis on the object side is concave, and the portion of the image-forming side closest to the optical axis is convex. In other embodiments, the object side and image-forming side of the sixth lens L6 may be provided with other concave-convex distributions.

[0053] When the focal length of the sixth lens L6 is f6, the following relationship is further satisfied: -4.36 ≤ f6 / f ≤ -0.83. This relationship specifies that the focal length of the sixth lens L6, which is the last lens, is short. Satisfying this relationship ensures excellent light collection and a sufficient amount of light passing through. It is preferable that -2.73 ≤ f6 / f ≤ -1.03 is satisfied.

[0054] The central radius of curvature of the object side surface of the sixth lens L6 is R11, and the central radius of curvature of the image-forming side surface of the sixth lens L6 is R12, further satisfying the relationship -3.71 ≤ (R11 + R12) / (R11 - R12) ≤ -0.72. This relationship defines the shape of the sixth lens L6. Within the range of this relationship, it is advantageous for the smooth transition of light rays and the image-forming mass can be improved. It is preferable that -2.32 ≤ (R11 + R12) / (R11 - R12) ≤ -0.90 is satisfied.

[0055] The optical axis thickness of the sixth lens L6 is d11, and it further satisfies the relationship expressed as 0.03 ≤ d11 / TTL ≤ 0.13. Miniaturization can be achieved within the range of this relationship. It is preferable that 0.06 ≤ d11 / TTL ≤ 0.11 is satisfied.

[0056] The imaging optical lens according to the present invention will be described below using examples. The reference numerals in each example are as follows. The units for focal length, on-axis distance, central radius of curvature, and on-axis thickness are mm.

[0057] TTL: Total optical length (the distance along the optical axis from the side surface of the first lens L1 to the image plane Si), in units of mm.

[0058] Aperture value FNO: This is the ratio of the effective focal length to the entrance pupil diameter of the imaging optical lens.

[0059] The present invention will be described in detail below using six embodiments, and one comparative embodiment will be described as a reference example. It will also be explained that the technical effects of the present invention cannot be obtained if the above-mentioned relation is not satisfied.

[0060] (First Embodiment) Table 1 shows the design data for the imaging optical lens 10 according to the first embodiment of the present invention. [Table 1]

[0061] The meaning of each symbol is as follows: S1: Aperture R1: Radius of curvature of the central side of the object at the first lens L1 R2: Center radius of curvature of the imaging side of the first lens L1 R3: Radius of curvature of the central side of the object at the second lens L2 R4: Center curvature radius of the imaging side of the second lens L2 R5: Radius of curvature of the central side of the object at the third lens L3 R6: Center curvature radius of the imaging side of the third lens L3 R7: Radius of curvature of the central side of the object at the fourth lens L4 R8: Radius of curvature of the central side of the image-forming surface of the fourth lens L4 R9: Radius of curvature of the central side of the object at lens L5 (5th lens) R10: Radius of central curvature of the imaging side of the fifth lens L5 R11: Radius of curvature of the central side of the object at lens L6 (6th lens) R12: Radius of central curvature of the imaging side of the sixth lens L6. R13: Radius of curvature of the central side surface of the optical filter GF R14: Center curvature radius of the imaging side of the optical filter GF d: Optical axial thickness of the lens, optical axial distance between lenses d1: Optical axis thickness of the first lens L1 d2: Distance along the optical axis from the imaging side of the first lens L1 to the object side of the second lens L2. d3: On-axis thickness of the second lens L2 d4: On-axis distance from the imaging side of the second lens L2 to the object side of the third lens L3. d5: On-axis thickness of the third lens L3 d6: On-axis distance from the imaging side of the third lens L3 to the object side of the fourth lens L4. d7: On-axis thickness of the 4th lens L4 d8: On-axis distance from the imaging side of the fourth lens L4 to the object side of the fifth lens L5. d9: On-axis thickness of the 5th lens L5 d10: On-axis distance from the imaging side of the 5th lens L5 to the object side of the 6th lens L6. d11: On-axis thickness of the 6th lens L6 d12: On-axis distance from the imaging side of the sixth lens L6 to the object side of the optical filter GF d13: On-axis thickness of optical filter GF d14: On-axis distance from the imaging side of the optical filter GF to the imaging plane Si nd: Refraction of the d-line (the d-line is green light with a wavelength of 550 nm) nd1: Refractive index of the d line of the first lens L1 nd2: Refractive index of the d line of the second lens L2 nd3: Refractive index of the d line of the third lens L3 nd4: Refractive index of the d line of lens L4 (4th lens) nd5: Refractive index of the d line of lens L5 (5th lens) nd6: Refractive index of the d line of lens L6 (6th lens) ndg: Refractive index of the d line in optical filter GF vd: Abbe number v1: Abbe number of the first lens L1 v2: Abbe number of the second lens L2 v3: Abbe number of the third lens L3 v4: Abbe number of the fourth lens L4 v5: Abbe number of lens L5 (5th lens) v6: Abbe number of lens L6 (6th lens) vg: Abbe number of optical filter GF

[0062] Table 2 shows the aspherical data of the first lens L1 and the fourth lens L4 in the imaging optical lens 10 according to the first embodiment of the present invention.

[0063] [Table 2]

[0064] For the sake of cost, the aspheric surfaces of each lens surface use the aspheric surface represented by the following formula (1). However, the present invention is not limited to the aspheric polynomial form represented by this formula (1). z = (cr 2 ) / {1 + [1 - (k + 1)(c 2 r 2 )] 1 / 2} + A4r 4 + A6r 6 + A8r 8 + A10r 10 + A12r 12 + A14r 14 + A16r 16 (1)

[0065] Here, k is the conic coefficient, A4, A6, A8, A10, A12, A14, A16 are the aspheric coefficients, c is the curvature of the center of the optical surface, r is the perpendicular distance between the point on the aspheric curve and the optical axis, and z is the aspheric depth (the perpendicular distance between the point where the distance from the optical axis in the aspheric surface is r and the tangent plane tangent to the vertex on the aspheric optical axis).

[0066] FIG. 2 and FIG. 3 are diagrams showing the axial chromatic aberration and the magnification chromatic aberration after light of wavelengths 700 nm, 625 nm, 550 nm, 500 nm, and 450 nm passes through the imaging optical lens 10 in the first embodiment. FIG. 4 is a diagram showing the field curvature and the distortion aberration after light of wavelength 550 nm passes through the imaging optical lens 10 of the first embodiment. The field curvature S in FIG. 4 is the field curvature in the sagittal direction, and T is the field curvature in the meridional direction.

[0067] Table 15 described later shows the values corresponding to the parameters defined by various numerical values and relational expressions in each embodiment.

[0068] As shown in Table 15, the first embodiment satisfies each relational expression.

[0069] In this embodiment, the imaging optical lens 10 has an entrance pupil diameter (ENPD) of 3.036 mm, an image height (IH) of 4.032 mm across the entire field of view, and a diagonal field of view (FOV) of 128.00°. As a result, the imaging optical lens 10 has sufficient correction of on-axial and off-axial chromatic aberration and possesses excellent optical characteristics.

[0070] (Second Embodiment) The second embodiment is almost identical to the first embodiment, and the meaning of the reference numerals is the same as in the first embodiment; therefore, only the differences will be shown below.

[0071] Figure 5 shows an imaging optical lens 20 according to a second embodiment of the present invention.

[0072] Table 3 shows the design data for the imaging optical lens 20 according to the second embodiment of the present invention.

[0073] [Table 3]

[0074] Table 4 shows the aspherical data of the first lens L1 and the fourth lens L4 in the imaging optical lens 20 according to the second embodiment of the present invention.

[0075] [Table 4]

[0076] Figures 6 and 7 show the axial chromatic aberration and lateral chromatic aberration after light with wavelengths of 700 nm, 625 nm, 550 nm, 500 nm, and 450 nm passes through the imaging optical lens 20 in the second embodiment, respectively. Figure 8 shows the field curvature and distortion after light with a wavelength of 550 nm passes through the imaging optical lens 20 in the second embodiment, where S is the sagittal field curvature and T is the meridional field curvature.

[0077] As shown in Table 15, the second embodiment satisfies each of the relational equations.

[0078] In this embodiment, the imaging optical lens 20 has an entrance pupil diameter (ENPD) of 2.693 mm, an image height (IH) of 3.768 mm across the entire field of view, and a diagonal field of view (FOV) of 128.00°. As a result, the imaging optical lens 20 has sufficient correction of on-axial and off-axial chromatic aberration and possesses excellent optical characteristics.

[0079] (Third embodiment) The third embodiment is almost identical to the first embodiment, and the meaning of the reference numerals is the same as in the first embodiment; therefore, only the differences will be shown below.

[0080] Figure 9 shows an imaging optical lens 30 according to a third embodiment of the present invention.

[0081] Table 5 shows the design data for the imaging optical lens 30 according to the third embodiment of the present invention.

[0082] [Table 5]

[0083] Table 6 shows the aspherical data of the first lens L1 and the fourth lens L4 in the imaging optical lens 30 according to the third embodiment of the present invention.

[0084] [Table 6]

[0085] Figures 10 and 11 show the axial chromatic aberration and lateral chromatic aberration after light with wavelengths of 700 nm, 625 nm, 550 nm, 500 nm, and 450 nm passes through the imaging optical lens 30 in the third embodiment, respectively. Figure 12 shows the field curvature and distortion after light with a wavelength of 550 nm passes through the imaging optical lens 30 in the third embodiment, where S is the sagittal field curvature and T is the meridional field curvature.

[0086] Table 15 shows the values ​​corresponding to each relation in this embodiment, according to the above relation. Clearly, the imaging optical lens 30 in this embodiment satisfies the above relation.

[0087] In this embodiment, the imaging optical lens 30 has an entrance pupil diameter (ENPD) of 3.183 mm, an image height (IH) of 4.026 mm across the entire field of view, and a diagonal field of view (FOV) of 128.00°. As a result, the imaging optical lens 30 has sufficient correction of on-axial and off-axial chromatic aberration and possesses excellent optical characteristics.

[0088] (Fourth Embodiment) The fourth embodiment is almost identical to the first embodiment, and the meaning of the reference numerals is the same as in the first embodiment; therefore, only the differences will be shown below.

[0089] Figure 13 shows an imaging optical lens 40 according to a fourth embodiment of the present invention.

[0090] Table 7 shows the design data for the imaging optical lens 40 according to the fourth embodiment of the present invention.

[0091] [Table 7]

[0092] Table 8 shows the aspherical data of the first lens L1 and the fourth lens L4 in the imaging optical lens 40 according to the fourth embodiment of the present invention.

[0093] [Table 8]

[0094] Figures 14 and 15 show the axial chromatic aberration and lateral chromatic aberration after light with wavelengths of 700 nm, 625 nm, 550 nm, 500 nm, and 450 nm passes through the imaging optical lens 40 in the fourth embodiment, respectively. Figure 16 shows the field curvature and distortion after light with a wavelength of 550 nm passes through the imaging optical lens 40 in the fourth embodiment, where S is the sagittal field curvature and T is the meridional field curvature.

[0095] Table 15 shows the values ​​corresponding to each relation in this embodiment, according to the above relation. Clearly, the imaging optical lens 40 in this embodiment satisfies the above relation.

[0096] In this embodiment, the entrance pupil diameter (ENPD) of the imaging optical lens 40 is 3.150 mm, the image height (IH) of the entire field of view is 4.201 mm, and the diagonal field of view (FOV) is 128.00°. As a result, the imaging optical lens 40 has sufficient correction of on-axial and off-axial chromatic aberration and possesses excellent optical characteristics.

[0097] (Fifth embodiment) The fifth embodiment is almost identical to the first embodiment, and the meaning of the reference numerals is the same as in the first embodiment; therefore, only the differences will be shown below.

[0098] Figure 17 shows an imaging optical lens 50 according to a fifth embodiment of the present invention.

[0099] Table 9 shows the design data for the imaging optical lens 50 according to the fifth embodiment of the present invention.

[0100] [Table 9]

[0101] Table 10 shows the aspherical data of the first lens L1 and the fourth lens L4 in the imaging optical lens 50 according to the fifth embodiment of the present invention.

[0102] [Table 10]

[0103] Figures 18 and 19 show the axial chromatic aberration and lateral chromatic aberration after light with wavelengths of 700 nm, 625 nm, 550 nm, 500 nm, and 450 nm passes through the imaging optical lens 50 in the fifth embodiment, respectively. Figure 20 shows the field curvature and distortion after light with a wavelength of 550 nm passes through the imaging optical lens 50 in the fifth embodiment, where S is the sagittal field curvature and T is the meridional field curvature.

[0104] Table 15 shows the values ​​corresponding to each relation in this embodiment, according to the above relation. Clearly, the imaging optical lens 50 in this embodiment satisfies the above relation.

[0105] In this embodiment, the entrance pupil diameter (ENPD) of the imaging optical lens 50 is 3.093 mm, the image height (IH) of the entire field of view is 4.068 mm, and the diagonal field of view (FOV) is 128.00°. As a result, the imaging optical lens 50 has sufficient correction of on-axial and off-axial chromatic aberration and possesses excellent optical characteristics.

[0106] (Sixth Embodiment) The sixth embodiment is almost identical to the first embodiment, and the meaning of the reference numerals is the same as in the first embodiment; therefore, only the differences will be shown below.

[0107] Figure 21 shows an imaging optical lens 60 according to the sixth embodiment of the present invention.

[0108] Table 11 shows the design data for the imaging optical lens 60 according to the sixth embodiment of the present invention.

[0109] [Table 11]

[0110] Table 12 shows the aspherical data of the first lens L1 and the fourth lens L4 in the imaging optical lens 60 according to the sixth embodiment of the present invention.

[0111] [Table 12]

[0112] Figures 22 and 23 show the axial chromatic aberration and lateral chromatic aberration after light with wavelengths of 700 nm, 625 nm, 550 nm, 500 nm, and 450 nm passes through the imaging optical lens 60 in the sixth embodiment, respectively. Figure 24 shows the field curvature and distortion after light with a wavelength of 550 nm passes through the imaging optical lens 60 in the sixth embodiment, where S is the sagittal field curvature and T is the meridional field curvature.

[0113] Table 15 shows the values ​​corresponding to each relation in this embodiment, according to the above relation. Clearly, the imaging optical lens 60 in this embodiment satisfies the above relation.

[0114] In this embodiment, the imaging optical lens 60 has an entrance pupil diameter (ENPD) of 2.445 mm, an image height (IH) of 3.648 mm across the entire field of view, and a diagonal field of view (FOV) of 128.00°. As a result, the imaging optical lens 60 has sufficient correction of on-axial and off-axial chromatic aberration and possesses excellent optical characteristics.

[0115] (Comparative Implementation) The comparative embodiment is almost identical to the first embodiment, and the meaning of the reference numerals is the same as in the first embodiment; therefore, only the differences are shown below.

[0116] Figure 25 shows an imaging optical lens 70 according to a comparative embodiment.

[0117] Table 13 shows the design data for the imaging optical lens 70 according to the comparative embodiment.

[0118] [Table 13]

[0119] Table 14 shows the aspherical data of the first lens L1 and the fourth lens L4 in the imaging optical lens 70 according to a comparative embodiment of the present invention.

[0120] [Table 14]

[0121] Figures 26 and 27 show the axial chromatic aberration and lateral chromatic aberration after light with wavelengths of 700 nm, 625 nm, 550 nm, 500 nm, and 450 nm passes through the imaging optical lens 70 in the comparative embodiment, respectively. Figure 28 shows the field curvature and distortion after light with a wavelength of 550 nm passes through the imaging optical lens 70 in the comparative embodiment, where S is the sagittal field curvature and T is the meridional field curvature.

[0122] Table 15 shows the values ​​corresponding to each relation in this embodiment, according to the above relation. Clearly, the imaging optical lens 70 in this embodiment satisfies the above relation.

[0123] In this embodiment, the entrance pupil diameter (ENPD) of the imaging optical lens 70 is 2.877 mm, the image height (IH) of the entire field of view is 4.003 mm, and the diagonal field of view (FOV) is 128.00°.

[0124] As a result, the imaging optical lens 70 has sufficient correction of axial and off-axial chromatic aberration, and possesses excellent optical characteristics.

[0125] Table 15 shows the values ​​corresponding to each relation in the comparative embodiment, according to the above relation. Clearly, the imaging optical lens 70 in this embodiment cannot satisfy the above relation 0.10 ≤ d2 / TTL ≤ 0.20, and therefore cannot effectively balance the amount of field curvature.

[0126] [Table 15]

[0127] While the embodiments described above are specific examples for realizing the present invention, those skilled in the art will understand that in actual applications, various modifications to the form and details can be made without departing from the spirit and scope of the present invention.

Claims

1. An imaging optical lens comprising a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having positive refractive power, a fifth lens having positive refractive power, and a sixth lens having negative refractive power, arranged in order from the object side toward the image-forming side, The distance along the optical axis from the image-forming side of the first lens to the object-facing side of the second lens is d2. The optical length of the aforementioned imaging optical lens is TTL. The focal length of the third lens is f3. The focal length of the fourth lens is f4. The central radius of curvature of the object side surface of the fourth lens is R7. The central radius of curvature of the image-forming side of the fourth lens is R8. 0.10 ≤ d² / TTL ≤ 0.20 0.60 ≤ f3 / f4 ≤ 1.40 0.01 ≤ R7 / R8 ≤ 0.30 The relationship expressed in the above equation satisfies An imaging optical lens characterized by the following features.

2. The central radius of curvature of the object side surface of the first lens is R1. The central radius of curvature of the image-forming side of the first lens is R2. 1.80≦(R1+R2) / (R1-R2)≦6.30 The relationship expressed in the above equation satisfies The imaging optical lens according to feature 1.

3. The fifth lens is provided bonded to the sixth lens. The imaging optical lens according to feature 1.

4. The Abbe number of the fifth lens is V5. The Abbe number of the sixth lens is V6. V5-V6≧35.00 The relationship expressed in the above equation satisfies The imaging optical lens according to claim 1 or 3.

5. The focal length of the aforementioned imaging optical lens is f. 5.00 ≤ TTL / f ≤ 7.00 The relationship expressed in the above equation satisfies The imaging optical lens according to feature 1.

6. The portion of the first lens closest to the optical axis on the side of the object is convex, The part of the first lens near the optical axis on the image-forming side is concave, The focal length of the aforementioned imaging optical lens is f. The focal length of the first lens is f1, The optical axis thickness of the first lens is d1, -6.21 ≤ f1 / f ≤ -0.97 0.01 ≤ d1 / TTL ≤ 0.10 The relationship expressed in the above equation satisfies The imaging optical lens according to feature 1.

7. The portion of the second lens closest to the optical axis on the side of the object is concave. The part of the second lens near the optical axis on the image-forming side is convex, The focal length of the aforementioned imaging optical lens is f. The focal length of the second lens is f2. The central radius of curvature of the object side surface of the second lens is R3. The central radius of curvature of the image-forming side of the second lens is R4. The optical axis thickness of the second lens is d3. -21.11 ≤ f² / f ≤ -3.75 -9.81≦(R3+R4) / (R3-R4)≦-2.45 0.06 ≤ d3 / TTL ≤ 0.26 The relationship expressed in the above equation satisfies The imaging optical lens according to feature 1.

8. The portion of the third lens closest to the optical axis on the side of the object is convex, The part of the third lens near the optical axis on the image-forming side is convex, The focal length of the aforementioned imaging optical lens is f. The central radius of curvature of the object side surface of the third lens is R5. The central radius of curvature of the image-forming side of the third lens is R6. The optical axis thickness of the third lens is d5. 1.18 ≤ f³ / f ≤ 5.80 -1.96≦(R5+R6) / (R5-R6)≦-0.31 0.02 ≤ d5 / TTL ≤ 0.26 The relationship expressed in the above equation satisfies The imaging optical lens according to feature 1.

9. The portion of the fourth lens closest to the optical axis on the side of the object is convex, The part of the fourth lens near the optical axis on the image-forming side is concave. The focal length of the aforementioned imaging optical lens is f. The optical axis thickness of the fourth lens is d7. 1.29 ≤ f₄ / f ≤ 5.84 -3.71≦(R7+R8) / (R7-R8)≦-0.68 0.07 ≤ d7 / TTL ≤ 0.26 The relationship expressed in the above equation satisfies The imaging optical lens according to feature 1.

10. The portion of the fifth lens closest to the optical axis on the side of the object is convex, The part of the fifth lens near the optical axis on the image-forming side is convex, The focal length of the aforementioned imaging optical lens is f. The focal length of the fifth lens is f5. The central radius of curvature of the object side surface of the fifth lens is R9. The central radius of curvature of the image-forming side of the fifth lens is R10. The optical axis thickness of the fifth lens is d9. 0.56 ≤ f5 / f ≤ 2.34 0.13≦(R9+R10) / (R9-R10)≦0.50 0.05 ≤ d9 / TTL ≤ 0.18 The relationship expressed in the above equation satisfies The imaging optical lens according to feature 1.

11. The portion of the sixth lens closest to the optical axis on the side of the object is concave. The portion of the sixth lens near the optical axis on the image-forming side is convex, The focal length of the aforementioned imaging optical lens is f. The focal length of the sixth lens is f / 6. The central radius of curvature of the object side surface of the sixth lens is R11. The central radius of curvature of the image-forming side of the sixth lens is R12. The optical axis thickness of the sixth lens is d11. -4.36 ≤ f6 / f ≤ -0.83 -3.71≦(R11+R12) / (R11-R12)≦-0.72 0.03 ≤ d11 / TTL ≤ 0.13 The relationship expressed in the above equation satisfies The imaging optical lens according to feature 1.

12. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all made of glass. The imaging optical lens according to feature 1.

Images