Imaging optical system and imaging device
The imaging optical system addresses the challenge of downsizing the first lens in in-vehicle and surveillance cameras by employing a specific lens configuration and conditional expressions, achieving wide-angle performance and improved aberration correction with reduced overall length and temperature stability.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NIDEC INSTR CORP
- Filing Date
- 2024-11-29
- Publication Date
- 2026-06-10
AI Technical Summary
Existing imaging optical systems for in-vehicle and surveillance cameras face challenges in downsizing the first lens while maintaining optical characteristics, particularly in terms of designability and reducing the feeling of being monitored.
The imaging optical system is designed with a specific configuration of lens groups and conditional expressions to achieve downsizing while maintaining optical performance, including a front group composed of a first and second lens, and a rear group composed of three lenses, with specific ratios and conditions to correct aberrations and reduce overall length.
The system effectively corrects various aberrations and reduces the overall length of the lens system, allowing for a wide-angle view while suppressing the increase in the first lens diameter and improving temperature stability.
Smart Images
Figure 2026094699000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an imaging optical system and an imaging device.
[0002] An imaging optical system used in an in-vehicle camera or a surveillance camera is described in Patent Document 1. The imaging optical system of Patent Document 1 includes an aperture stop, a first lens group disposed on the object side of the aperture stop, and a second lens group disposed on the image side of the aperture stop. The first lens group is composed of two lenses. The second lens group is composed of four lenses. Among the lenses of the first lens group, the first lens disposed closest to the object side is exposed from a lens barrel or the like that covers the imaging optical system.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In an imaging optical system used in an in-vehicle camera or a surveillance camera, downsizing of the first lens is required from the viewpoints of designability and suppressing the feeling that the user is being monitored. However, in the imaging optical system of Patent Document 1, it is difficult to downsize the first lens while suppressing deterioration of optical characteristics.
[0005] In view of the above problems, an object of the present invention is to provide an imaging optical system capable of downsizing the first lens while suppressing deterioration of optical characteristics, and an imaging device including the imaging optical system.
Means for Solving the Problems
[0006] To solve the above problems, one aspect of the imaging optical system of the present invention includes a front group, an aperture stop, and a rear group in order from the object side to the image side. The aforementioned front group consists of a first lens and a second lens, arranged in order from the object side to the image side. The aforementioned rear group consists of a third lens, a fourth lens, a fifth lens, and a sixth lens, in order from the object side towards the image side. If the horizontal field of view is HFOV, the total length between the lenses of the front group is df, and the total length between the lenses of the rear group is dr, then the following conditional expression The following conditional expression 100 < HFOV (1) df / dr <0.580 (2) It is characterized by satisfying the following conditions.
[0007] One embodiment of the imaging apparatus of the present invention is characterized by comprising an imaging optical system and an image sensor disposed on the image side of the imaging optical system. [Brief explanation of the drawing]
[0008] [Figure 1] Figure 1 is an explanatory diagram of an imaging device according to Embodiment 1. [Figure 2] Figure 2 shows the data of the imaging optical system of Embodiment 1. [Figure 3] Figure 3 shows the spherical aberration of the imaging optical system shown in Figure 1. [Figure 4] Figure 4 shows the chromatic aberration of the imaging optical system shown in Figure 1. [Figure 5] Figure 5 shows the astigmatism and distortion of the imaging optical system shown in Figure 1. [Figure 6] Figure 6 shows the lateral aberration of the imaging optical system shown in Figure 1. [Figure 7] Figure 7 is an explanatory diagram of the imaging device according to Embodiment 2. [Figure 8] Figure 8 shows the data from the imaging optical system of Embodiment 2. [Figure 9] Figure 9 shows the spherical aberration of the imaging optical system shown in Figure 7. [Figure 10] Figure 10 shows the chromatic aberration of the imaging optical system shown in Figure 7. [Figure 11] FIG. 11 is a diagram showing the aberration and distortion of the imaging optical system shown in FIG. 7. [Figure 12] FIG. 12 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. 7. [Figure 13] FIG. 13 is an explanatory diagram of the imaging device according to Embodiment 3. [Figure 14] FIG. 14 is a diagram showing data of the imaging optical system of Embodiment 3. [Figure 15] FIG. 15 is a diagram showing the spherical aberration of the imaging optical system shown in FIG. 13. [Figure 16] FIG. 16 is a diagram showing the chromatic aberration of magnification of the imaging optical system shown in FIG. 13. [Figure 17] FIG. 17 is a diagram showing the aberration and distortion of the imaging optical system shown in FIG. 13. [Figure 18] FIG. 18 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. 13. [Figure 19] FIG. 19 is an explanatory diagram of the imaging device according to Embodiment 4. [Figure 20] FIG. 20 is a diagram showing data of the imaging optical system of Embodiment 4. [Figure 21] FIG. 21 is a diagram showing the spherical aberration of the imaging optical system shown in FIG. 19. [Figure 22] FIG. 22 is a diagram showing the chromatic aberration of magnification of the imaging optical system shown in FIG. 19. [[ID=3,6]] [Figure 23] FIG. 23 is a diagram showing the aberration and distortion of the imaging optical system shown in FIG. 19. [Figure 24] FIG. 24 is a diagram showing the lateral aberration of the imaging optical system shown in FIG. 19. [Figure 25] FIG. 25 is an explanatory diagram of the imaging device according to Embodiment 5. [Figure 26] FIG. 26 is a diagram showing data of the imaging optical system of Embodiment 5. [Figure 27] FIG. 27 is a diagram showing the spherical aberration of the imaging optical system shown in FIG. 25. [Figure 28] FIG. 28 is a diagram showing the chromatic aberration of magnification of the imaging optical system shown in FIG. 25. [Figure 29] Figure 29 shows the astigmatism and distortion of the imaging optical system shown in Figure 25. [Figure 30] Figure 30 shows the lateral aberration of the imaging optical system shown in Figure 25. [Modes for carrying out the invention]
[0009] The following describes an embodiment of an imaging device 200 equipped with an imaging optical system 100 to which the present invention is applied. The imaging device 200 is used in in-vehicle cameras and surveillance cameras. In particular, the imaging optical system 100 is suitable for use in surveillance cameras for monitoring inside vehicles.
[0010] (Embodiment 1) Figure 1 is an explanatory diagram of an imaging device 200 according to Embodiment 1. As shown in Figure 1, the imaging device 200 of this embodiment comprises an imaging optical system 100 and an image sensor 140. The imaging optical system 100 comprises, in order from the object side La to the image side Lb, a front group 110, an aperture 130, a rear group 120, and an infrared cut filter 80.
[0011] The front group 110 consists of a first lens 10 and a second lens 20, arranged in order from the object side La to the image side Lb. The rear group 120 consists of a third lens 30, a fourth lens 40, a fifth lens 50, and a sixth lens 60, arranged in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 70 joined by adhesive. On the image side Lb of the sixth lens 60, a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140 are arranged in order from the object side La to the image side Lb. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.
[0012] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The first lens 10 has aspherical shapes on both sides.
[0013] The second lens 20 is made of resin. The second lens 20 has positive power. The second lens 20 has a concave shape on the lens surface 21 on the object side La and a convex shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.
[0014] The third lens 30 is made of glass. The third lens 30 has positive power. The third lens 30 has a concave shape on the lens surface 31 on the object side La and a convex shape on the lens surface 32 on the image side Lb.
[0015] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a convex shape on the lens surface 41 on the object side La and a concave shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.
[0016] The fifth lens 50 is made of resin. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The fifth lens 50 has aspherical shapes on both sides.
[0017] The sixth lens 60 is made of resin. The sixth lens 60 has positive power. The sixth lens 60 has a convex shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides.
[0018] Figure 2 shows the data from the imaging optical system 100 of Embodiment 1. Note that the values shown in Figure 2 have been rounded.
[0019] Figure 2 shows the following various data. Here, in the various data, the total length of the entire lens system is the distance along the optical axis L from the object-side lens surface 11 of the first lens 10 (La) to the imaging surface of the image sensor 140. The total length between the first lens and the sixth lens is the distance along the optical axis L from the object-side lens surface 11 of the first lens 10 (La) to the image-side lens surface 62 of the sixth lens (Lb).
[0020] The effective focal length (f0) of the entire lens system. Total length of the entire lens system (Total Track: d0) The F-number (Fno) of the entire lens system Maximum half-angle (ω) Pupil Diameter Total length between the 1st lens and the 6th lens (L1R1-L6R2 Track) Horizontal field of view (HFOV)
[0021] Figure 2 also shows the lens data for each lens listed below. In the lens data, surfaces marked with an asterisk (*) are aspherical. R is the radius of curvature. d is the interplanar spacing. N is the refractive index. v is the Abbe number. f is the focal length. sd is the effective radius. The units for radius of curvature, interplanar spacing, and focal length are mm. Figure 2 also shows the aspherical coefficient, which indicates the shape of the aspherical surface for each surface number.
[0022] If the imaging optical system 100 has a horizontal field of view of HFOV, the total length between the lenses of the front group 110 is df, and the total length between the lenses of the rear group 120 is dr, The following conditional expression 100 < HFOV (1) df / dr <0.580 (2) It satisfies the condition. more, 100 < HFOV < 160 (1A) It satisfies the condition. more, 0.200 < df / dr < 0.580 (8) It satisfies the condition. More preferably, 0.350 < df / dr < 0.400 It satisfies the condition.
[0023] In this form, HFOV = 142.951 df=3.520 dr=9.820 Therefore, HFOV = 142.951, satisfying condition (1)(1A). df / dr = 0.358, satisfying condition (2)(8).
[0024] If the thickness of the third lens 30 of the imaging optical system 100 is T3 and the focal length of the entire lens system is f0, then the following conditional equation 1.000 < T3 / f0 < 2.000 (3) It satisfies the condition.
[0025] In this form, T3 = 3.450 f0 = 2.452 Therefore, T3 / f0 = 1.407, which satisfies condition (3).
[0026] If the imaging optical system 100 has a radius of curvature of the object-side lens surface 31 of the third lens 30 as R31 and a radius of curvature of the image-side lens surface 32 of the third lens as R32, then the following conditional equation 1.000< (R31+R32) / (R31-R32) <1.500 (4) It satisfies the condition. more, 1.000< (R31+R32) / (R31-R32) <1.300 It satisfies the condition.
[0027] In this form, R31 = -49.000 R32 = -3.470 Therefore, (R31+R32) / (R31-R32)=1.152, which satisfies condition (4).
[0028] If the imaging optical system 100 has a total focal length of f0 and the focal length of the third lens 30 is f3, then the following conditional equation 1.800 < f3 / f0 < 4.000 (5) It satisfies the condition.
[0029] In this form, f3 = 6.127 f0 = 2.452 Therefore, f3 / f0 = 2.499, which satisfies condition (5).
[0030] If the total length of the entire lens system of the imaging optical system 100 is d0, and the effective radius of the object-side lens surface 11 of the first lens 10 is sd11, then the following conditional equation 3.000 < d0 / sd11 < 5.500 (6) It satisfies the condition. more, 3.500 < d0 / sd11 < 4.500 It satisfies the condition.
[0031] In this form, d0 = 15.913 sd11 = 3.750 Therefore, d0 / sd11 = 4.243, which satisfies condition (6).
[0032] If the focal length of the entire lens system is f0 and the total length of the entire lens system is d0, then the following conditional equation applies to the imaging optical system 100. 5.500 < d0 / f0 < 9.000 (7) It satisfies the condition.
[0033] In this form, d0 = 15.913 f0 = 2.452 Therefore, d0 / f0 = 6.490, which satisfies condition (7).
[0034] The imaging optical system 100, with the total length of the entire lens system being d0 and the maximum image height being IH, is subject to the following conditional equation 2.000 < d0 / IH < 4.000 (9) It satisfies the condition.
[0035] In this form, d0 = 15.913 IH = 2.880 Therefore, d0 / IH = 5.525, which satisfies condition (9).
[0036] (Effects and Benefits) The imaging optical system 100 in this configuration satisfies both condition (1) and condition (2), so that the imaging optical system 100 is wide-angle and can properly correct various aberrations while suppressing an increase in the outer diameter of the first lens 10. When condition (1) is satisfied, if the value of condition (2) exceeds the upper limit, the outer diameter of the first lens 10 becomes too large if the total length dr between the lenses of the rear group 120 is small compared to the total length df between the lenses of the front group 110. Also, if the total length dr between the lenses of the rear group 120 is small compared to the total length df between the lenses of the front group 110, various aberrations cannot be properly corrected in the rear group 120. Furthermore, if the value of condition (1A) exceeds the upper limit, the imaging optical system 100 can achieve an ultra-wide angle, but the optical performance deteriorates due to an increase in various aberrations. Furthermore, if the value of condition (8) falls below the lower limit, various aberrations can be properly corrected in the rear group 120, but the overall length of the lens becomes larger.
[0037] The imaging optical system 100 in this configuration satisfies condition (3), so by suppressing the angle of light rays emitted from the third lens 30 adjacent to the aperture 130, various aberrations can be properly corrected. If the value of condition (3) falls below the lower limit, the thickness of the third lens 30 decreases, so the angle of light rays emitted from the third lens 30 increases. As a result, various aberrations cannot be properly corrected in the rear group 120. If the value of condition (3) exceeds the upper limit, various aberrations can be properly corrected in the rear group 120, but the thickness of the third lens 30 increases, so the overall length of the lens increases.
[0038] The third lens 30 has a concave shape on the object-side lens surface 31 La and a convex shape on the image-side lens surface 32 Lb. This allows for a larger optical path length in the third lens 30, thereby suppressing the angle of the light rays emitted from the third lens 30. As a result, various aberrations can be effectively corrected in the rear group 120. Furthermore, because the third lens 30 has a concave shape on the object-side lens surface 31 La, the outer surface of the flange portion, which is the outer circumference of the third lens 30, can be made into a straight surface parallel to the optical axis L when the third lens 30 is formed. As a result, when assembling the third lens 30 into the lens barrel, alignment of the third lens 30 in the direction of the optical axis L becomes easier.
[0039] The third lens 30 is made of glass. The first lens 10, second lens 20, fourth lens 40, fifth lens 50, and sixth lens 60 are made of resin. This results in good temperature characteristics for the imaging optical system 100.
[0040] In this embodiment of the imaging optical system 100, the third lens 30 has positive power and satisfies condition (4), so the lens surface 31 is concave and the lens surface 32 is convex, and the deterioration of the optical characteristics due to temperature changes in the imaging optical system 100 can be suppressed. If the value of condition (4) exceeds the upper limit, the power of the third lens 30 decreases, and the temperature characteristics of the imaging optical system 100 cannot be properly corrected.
[0041] The imaging optical system 100 in this configuration satisfies condition (5), so aberrations can be properly corrected. If the value of condition (5) falls below the lower limit, the power of the third lens 30 becomes too strong, making it difficult to suppress the occurrence of aberrations. If the value of condition (3) exceeds the upper limit, the power of the third lens 30 decreases, which can suppress the occurrence of aberrations, but the overall length of the lens system tends to increase.
[0042] The imaging optical system 100 in this configuration satisfies condition (6), so various aberrations can be corrected well, and the overall length of the lens system can be reduced. If the value of condition (6) falls below the lower limit, the angle of the light rays incident on the image sensor 140 becomes large, and various aberrations cannot be corrected well. If the value of condition (6) exceeds the upper limit, various aberrations can be corrected well, but the overall length of the lens becomes larger.
[0043] The imaging optical system 100 in this configuration satisfies condition (7), thus suppressing an increase in the overall length of the lens system and suppressing the occurrence of various aberrations. If the value of condition (7) falls below the lower limit, it is difficult to suppress the occurrence of various aberrations. If the value of condition (7) exceeds the upper limit, each lens system tends to become larger, and the overall length of the lens system also tends to increase.
[0044] The imaging optical system 100 in this embodiment satisfies condition (9), so various aberrations can be corrected well, and the overall length of the lens system can be reduced. If the value of condition (9) falls below the lower limit, the angle of the light rays incident on the image sensor 140 becomes large, and various aberrations cannot be corrected well. If the value of condition (9) exceeds the upper limit, various aberrations cannot be corrected well. It can be corrected, but the overall length of the lens increases.
[0045] Figure 3 shows the spherical aberration of the imaging optical system 100 shown in Figure 1. Figure 4 shows the lateral chromatic aberration of the imaging optical system 100 shown in Figure 1, showing the lateral chromatic aberration at the maximum half-angle of view. Figure 5 shows the astigmatism and distortion of the imaging optical system 100 shown in Figure 1. Figure 6 shows the lateral aberration of the imaging optical system 100 shown in Figure 1, showing the lateral aberration in the tangential direction (Y direction) and the sagittal direction (X direction).
[0046] Figures 3 to 6 show the aberrations at wavelengths of 486 nm, 588 nm, and 656 nm, denoted by B, G, and R, respectively. For the astigmatism shown in Figure 5, the sagittal characteristic is denoted by S, and the tangential characteristic is denoted by T.
[0047] As shown in Figures 3 to 6, in the imaging optical system 100 of this embodiment, spherical aberration, lateral chromatic aberration, astigmatism (distortion), and lateral aberration are corrected to an appropriate level.
[0048] (Embodiment 2) Figure 7 is an explanatory diagram of an imaging device 200 according to Embodiment 2. As shown in Figure 7, the imaging device 200 of this embodiment comprises an imaging optical system 100 and an image sensor 140. The imaging optical system 100 comprises, in order from the object side La to the image side Lb, a front group 110, an aperture 130, a rear group 120, and an infrared cut filter 80.
[0049] The front group 110 consists of a first lens 10 and a second lens 20, arranged in order from the object side La to the image side Lb. The rear group 120 consists of a third lens 30, a fourth lens 40, a fifth lens 50, and a sixth lens 60, arranged in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 70 joined by adhesive. On the image side Lb of the sixth lens 60, a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140 are arranged in order from the object side La to the image side Lb. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.
[0050] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The first lens 10 has an aspherical shape on the lens surface 12.
[0051] The second lens 20 is made of resin. The second lens 20 has positive power. The second lens 20 has a concave shape on the lens surface 21 on the object side La and a convex shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.
[0052] The third lens 30 is made of glass. The third lens 30 has positive power. The third lens 30 has a concave shape on the lens surface 31 on the object side La and a convex shape on the lens surface 32 on the image side Lb.
[0053] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a convex shape on the lens surface 41 on the object side La and a concave shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.
[0054] The fifth lens 50 is made of resin. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The fifth lens 50 has aspherical shapes on both sides.
[0055] The sixth lens 60 is made of resin. The sixth lens 60 has positive power. Lens 60 has a convex shape on the object-side lens surface 61 La and a concave shape on the image-side lens surface 62 Lb. The sixth lens 60 has an aspherical shape on both sides.
[0056] (Lens configuration) Figure 8 shows the data from the imaging optical system 100 of Embodiment 2. The imaging optical system 100 of this embodiment satisfies the conditions (1) to (9) described in Embodiment 1.
[0057] In this form, HFOV = 143.114 df=3.520 dr=9.723 Therefore, HFOV = 143.114, satisfying condition (1)(1A). df / dr = 0.362, satisfying condition (2)(8).
[0058] In this form, T3 = 3.356 f0 = 2.428 Therefore, T3 / f0 = 1.382, which satisfies condition (3).
[0059] In this form, R31 = -47.975 R32 = -3.471 Therefore, (R31+R32) / (R31-R32)=1.156, which satisfies condition (4).
[0060] In this form, f3 = 6.141 f0 = 2.428 Therefore, f3 / f0 = 2.529, which satisfies condition (5).
[0061] In this form, d0 = 15.890 sd11 = 3.819 Therefore, d0 / sd11 = 4.160, which satisfies condition (6).
[0062] In this form, d0 = 15.890 f0 = 2.428 Therefore, d0 / f0 = 6.543, which satisfies condition (7).
[0063] In this form, d0 = 15.890 IH = 2.880 Therefore, d0 / IH = 5.517, which satisfies condition (9).
[0064] (Effects and Benefits) The imaging optical system 100 of Embodiment 2 satisfies the same conditions (1) to (9) as in Embodiment 1, and therefore can achieve the same effects as Embodiment 1.
[0065] Figure 9 shows the spherical aberration of the imaging optical system 100 shown in Figure 7. Figure 10 shows the spherical aberration of the imaging optical system 100 shown in Figure 7. Figure 11 shows the chromatic aberration of the imaging optical system 100 shown in Figure 7, and the astigmatism and distortion of the imaging optical system 100 shown in Figure 7. Figure 12 shows the lateral aberration of the imaging optical system 100 shown in Figure 7.
[0066] As shown in Figures 9 to 12, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration, astigmatism (distortion), transverse aberration, and resolution are corrected to an appropriate level.
[0067] (Embodiment 3) Figure 13 is an explanatory diagram of an imaging device 200 according to Embodiment 3. As shown in Figure 13, the imaging device 200 of this embodiment comprises an imaging optical system 100 and an image sensor 140. The imaging optical system 100 comprises, in order from the object side La to the image side Lb, a front group 110, an aperture 130, a rear group 120, and an infrared cut filter 80.
[0068] The front group 110 consists of a first lens 10 and a second lens 20, arranged in order from the object side La to the image side Lb. The rear group 120 consists of a third lens 30, a fourth lens 40, a fifth lens 50, and a sixth lens 60, arranged in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 70 joined by adhesive. On the image side Lb of the sixth lens 60, a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140 are arranged in order from the object side La to the image side Lb. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.
[0069] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The first lens 10 has an aspherical shape on the lens surface 12.
[0070] The second lens 20 is made of resin. The second lens 20 has positive power. The second lens 20 has a concave shape on the lens surface 21 on the object side La and a convex shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.
[0071] The third lens 30 is made of glass. The third lens 30 has positive power. The third lens 30 has a concave shape on the lens surface 31 on the object side La and a convex shape on the lens surface 32 on the image side Lb.
[0072] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a convex shape on the lens surface 41 on the object side La and a concave shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.
[0073] The fifth lens 50 is made of resin. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The fifth lens 50 has aspherical shapes on both sides.
[0074] The sixth lens 60 is made of resin. The sixth lens 60 has positive power. The sixth lens 60 has a convex shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides.
[0075] (Lens configuration) Figure 14 shows the data of the imaging optical system 100 of Embodiment 3. The imaging optical system 100 of this embodiment satisfies the conditions (1) to (9) described in Embodiment 1.
[0076] In this form, HFOV = 142.947 df=3.520 dr=9.827 Therefore, HFOV = 142.947, satisfying condition (1)(1A). df / dr = 0.358, satisfying condition (2)(8).
[0077] In this form, T3 = 3.451 f0 = 2.454 Therefore, T3 / f0 = 1.407, which satisfies condition (3).
[0078] In this form, R31 = -48.868 R32 = -3.468 Therefore, (R31+R32) / (R31-R32)=1.153, which satisfies condition (4).
[0079] In this form, f3 = 6.124 f0 = 2.454 Therefore, f3 / f0 = 2.496, which satisfies condition (5).
[0080] In this form, d0 = 15.905 sd11 = 3.796 Therefore, d0 / sd11 = 4.190, which satisfies condition (6).
[0081] In this form, d0 = 15.905 f0 = 2.454 Therefore, d0 / f0 = 6.483, which satisfies condition (7).
[0082] In this form, d0 = 15.905 IH = 2.880 Therefore, d0 / IH = 5.523, which satisfies condition (9).
[0083] (Effects and Benefits) The imaging optical system 100 of Embodiment 3 satisfies the same conditions (1) to (9) as in Embodiment 1, and therefore can achieve the same effects as Embodiment 1.
[0084] Figure 15 shows the spherical aberration of the imaging optical system 100 shown in Figure 13. Figure 16 shows the lateral chromatic aberration of the imaging optical system 100 shown in Figure 13. Figure 17 shows the astigmatism and distortion of the imaging optical system 100 shown in Figure 13. Figure 18 shows the lateral aberration of the imaging optical system 100 shown in Figure 13.
[0085] As shown in Figures 15 to 18, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration, astigmatism (distortion), transverse aberration, and resolution are corrected to an appropriate level.
[0086] (Embodiment 4) Figure 19 is an explanatory diagram of an imaging device 200 according to Embodiment 4. As shown in Figure 19, the imaging device 200 of this embodiment comprises an imaging optical system 100 and an image sensor 140. The imaging optical system 100 comprises, in order from the object side La to the image side Lb, a front group 110, an aperture 130, a rear group 120, and an infrared cut filter 80.
[0087] The front group 110 consists of a first lens 10 and a second lens 20, arranged in order from the object side La to the image side Lb. The rear group 120 consists of a third lens 30, a fourth lens 40, a fifth lens 50, and a sixth lens 60, arranged in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 70 joined by adhesive. On the image side Lb of the sixth lens 60, a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140 are arranged in order from the object side La to the image side Lb. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.
[0088] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The first lens 10 has an aspherical shape on the lens surface 12.
[0089] The second lens 20 is made of resin. The second lens 20 has positive power. The second lens 20 has a concave shape on the lens surface 21 on the object side La and a convex shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.
[0090] The third lens 30 is made of glass. The third lens 30 has positive power. The third lens 30 has a concave shape on the lens surface 31 on the object side La and a convex shape on the lens surface 32 on the image side Lb.
[0091] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a convex shape on the lens surface 41 on the object side La and a concave shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.
[0092] The fifth lens 50 is made of resin. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The fifth lens 50 has aspherical shapes on both sides.
[0093] The sixth lens 60 is made of resin. The sixth lens 60 has positive power. The sixth lens 60 has a convex shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides.
[0094] (Lens configuration) Figure 20 shows the data of the imaging optical system 100 of Embodiment 4. The imaging optical system 100 of this embodiment satisfies the conditions (1) to (9) described in Embodiment 1.
[0095] In this form, HFOV = 143.065 df=3.520 dr=9.811 Therefore, HFOV = 143.065, satisfying condition (1)(1A). df / dr = 0.359, satisfying condition (2)(8).
[0096] In this form, T3 = 3.410 f0 = 2.486 Therefore, T3 / f0 = 1.372, which satisfies condition (3).
[0097] In this form, R31 = -39.464 R32 = -3.451 Therefore, (R31+R32) / (R31-R32)=1.192, which satisfies condition (4).
[0098] In this form, f3 = 6.162 f0 = 2.486 Therefore, f3 / f0 = 2.478, which satisfies condition (5).
[0099] In this form, d0 = 15.911 sd11 = 3.774 Therefore, d0 / sd11 = 4.216, which satisfies condition (6).
[0100] In this form, d0 = 15.911 f0 = 2.486 Therefore, d0 / f0 = 6.400, which satisfies condition (7).
[0101] In this form, d0 = 15.911 IH = 2.880 Therefore, d0 / IH = 5.525, which satisfies condition (9).
[0102] (Effects and Benefits) The imaging optical system 100 of Embodiment 4 satisfies the same conditions (1) to (9) as in Embodiment 1, and therefore can achieve the same effects as Embodiment 1.
[0103] Figure 21 shows the spherical aberration of the imaging optical system 100 shown in Figure 19. Figure 22 shows the lateral chromatic aberration of the imaging optical system 100 shown in Figure 19. Figure 23 shows the astigmatism and distortion of the imaging optical system 100 shown in Figure 19. Figure 24 shows the lateral aberration of the imaging optical system 100 shown in Figure 19.
[0104] As shown in Figures 21 to 24, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration, astigmatism (distortion), transverse aberration, and resolution are corrected to an appropriate level.
[0105] (Embodiment 5) Figure 25 is an explanatory diagram of an imaging device 200 according to Embodiment 5. As shown in Figure 25, the imaging device 200 of this embodiment comprises an imaging optical system 100 and an image sensor 140. The imaging optical system 100 comprises, in order from the object side La to the image side Lb, a front group 110, an aperture 130, a rear group 120, and an infrared cut filter 80.
[0106] The front group 110 consists of a first lens 10 and a second lens 20, arranged in order from the object side La to the image side Lb. The rear group 120 consists of a third lens 30, a fourth lens 40, a fifth lens 50, and a sixth lens 60, arranged in order from the object side La to the image side Lb. The fourth lens 40 and the fifth lens 50 are bonded lenses 70 joined by adhesive. On the image side Lb of the sixth lens 60, a flat infrared cut filter 80, a light-transmitting cover 90, and an image sensor 140 are arranged in order from the object side La to the image side Lb. The image sensor 140 is positioned on the imaging plane of the image side Lb of the imaging optical system 100.
[0107] The first lens 10 is made of resin. The first lens 10 has negative power. The first lens 10 has a convex shape on the lens surface 11 on the object side La and a concave shape on the lens surface 12 on the image side Lb. The first lens 10 has an aspherical shape on the lens surface 12.
[0108] The second lens 20 is made of resin. The second lens 20 has positive power. The second lens 20 has a concave shape on the lens surface 21 on the object side La and a convex shape on the lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides.
[0109] The third lens 30 is made of glass. The third lens 30 has positive power. The third lens 30 has a concave shape on the lens surface 31 on the object side La and a convex shape on the lens surface 32 on the image side Lb.
[0110] The fourth lens 40 is made of resin. The fourth lens 40 has negative power. The fourth lens 40 has a convex shape on the lens surface 41 on the object side La and a concave shape on the lens surface 42 on the image side Lb. The fourth lens 40 has aspherical shapes on both sides.
[0111] The fifth lens 50 is made of resin. The fifth lens 50 has positive power. The fifth lens 50 has a convex shape on the lens surface 51 on the object side La and a convex shape on the lens surface 52 on the image side Lb. The fifth lens 50 has aspherical shapes on both sides.
[0112] The sixth lens 60 is made of resin. The sixth lens 60 has positive power. The sixth lens 60 has a convex shape on the lens surface 61 on the object side La and a concave shape on the lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides.
[0113] (Lens configuration) Figure 26 shows the data from the imaging optical system 100 of Embodiment 5. The imaging optical system 100 of this embodiment satisfies the conditions (1) to (9) described in Embodiment 1.
[0114] In this form, HFOV = 143.061 df=3.555 dr=9.752 Therefore, HFOV = 143.065, satisfying condition (1)(1A). df / dr = 0.365, satisfying condition (2)(8).
[0115] In this form, T3 = 3.405 f0 = 2.481 Therefore, T3 / f0 = 1.372, which satisfies condition (3).
[0116] In this form, R31 = -33.359 R32 = -3.439 Therefore, (R31+R32) / (R31-R32)=1.230, which satisfies condition (4).
[0117] In this form, f3 = 6.206 f0 = 2.481 Therefore, f3 / f0 = 2.502, which satisfies condition (5).
[0118] In this form, d0 = 15.904 sd11 = 3.772 Therefore, d0 / sd11 = 4.216, which satisfies condition (6).
[0119] In this form, d0 = 15.904 f0 = 2.481 Therefore, d0 / f0 = 6.411, which satisfies condition (7).
[0120] In this form, d0 = 15.904 IH = 2.880 Therefore, d0 / IH = 5.522, which satisfies condition (9).
[0121] (Effects and Benefits) The imaging optical system 100 of Embodiment 5 satisfies the same conditions (1) to (9) as in Embodiment 1, and therefore can achieve the same effects as Embodiment 1.
[0122] Figure 27 shows the spherical aberration of the imaging optical system 100 shown in Figure 25. Figure 28 shows the lateral chromatic aberration of the imaging optical system 100 shown in Figure 25. Figure 29 shows the astigmatism and distortion of the imaging optical system 100 shown in Figure 25. Figure 30 shows the lateral aberration of the imaging optical system 100 shown in Figure 25.
[0123] As shown in Figures 27 to 30, in the imaging optical system 100 of this embodiment, spherical aberration, chromatic aberration, astigmatism (distortion), transverse aberration, and resolution are corrected to an appropriate level.
[0124] Furthermore, this technology can be configured as follows:
[0125] (Note 1) The lens group, arranged in order from the object side to the image side, consists of a front group, an aperture, and a rear group. The aforementioned front group consists of a first lens and a second lens, arranged in order from the object side to the image side. The aforementioned rear group consists of a third lens, a fourth lens, a fifth lens, and a sixth lens, in order from the object side towards the image side. If the horizontal field of view is HFOV, the total length between the lenses of the front group is df, and the total length between the lenses of the rear group is dr, then the following conditional expression 100 < HFOV (1) df / dr <0.580 (2) An imaging optical system characterized by satisfying the following conditions.
[0126] (Note 2) If the thickness of the third lens is T3 and the focal length of the entire lens system is f0, then the following conditional equation 1.000 < T3 / f0 < 2.000 (3) The imaging optical system described in Appendix 1, characterized in that it satisfies the requirements.
[0127] (Note 3) The imaging optical system according to Appendix 1 or 2, characterized in that the third lens has positive power, a concave shape on the object-side lens surface, and a convex shape on the image-side lens surface.
[0128] (Note 4) The aforementioned third lens is made of glass, If the radius of curvature of the object-side lens surface of the third lens is R31, and the radius of curvature of the image-side lens surface of the third lens is R32, then the following conditional equation 1.000< (R31+R32) / (R31-R32) <1.500 (4) The imaging optical system described in Appendix 3, characterized in that it satisfies the requirements.
[0129] (Note 5) If the focal length of the entire lens system is f0 and the focal length of the third lens is f3, then the following conditional equation 1.800 < f3 / f0 < 4.000 (5) An imaging optical system as described in any one of the appendices 1 to 4, characterized in that it satisfies the following conditions.
[0130] (Note 6) If the total length of the lens system is d0, the effective radius of the object-side lens surface of the first lens is sd11, and the maximum image height is IH, then the following conditional equation 3.000 < d0 / sd11 < 5.500 (6) An imaging optical system as described in any one of the appendices 1 to 5, characterized in that it satisfies the following conditions.
[0131] (Note 7) If the focal length of the entire lens system is f0 and the total length of the entire lens system is d0, then the following conditional equation 5.500 < d0 / f0 < 9.000 (7) An imaging optical system as described in any one of the appendices 1 to 6, characterized in that it satisfies the following conditions.
[0132] (Note 8) If the total length between the lenses of the front group is denoted as df, and the total length between the lenses of the rear group is denoted as dr, The following conditional expression 0.200 < df / dr < 0.580 (8) An imaging optical system as described in any one of the appendices 1 to 7, characterized in that it satisfies the following conditions.
[0133] (Note 9) If the total length of the lens system is d0 and the maximum image height is IH, then the following conditional equation 2.000 < d0 / IH < 4.000 (9) An imaging optical system as described in any one of the appendices 1 to 8, characterized by satisfying the following conditions.
[0134] (Note 10) The imaging optical system described in any one of the appendices 1 to 9, The imaging sensor is positioned on the image side of the aforementioned imaging optical system, An imaging device characterized by comprising: [Explanation of symbols]
[0135] 100...Imaging optical system, 110...Front group, 120...Rear group, 200...Imaging device, 10...First lens, 20...Second lens, 30...Third lens, 40...Fourth lens, 50...Fifth lens, 60...Sixth lens, 70...Cemented lens, 80...Infrared cut filter, 90...Cover, 130...Aperture, 140...Image sensor.
Claims
1. The lens group, arranged in order from the object side to the image side, consists of a front group, an aperture, and a rear group. The aforementioned front group consists of a first lens and a second lens, arranged in order from the object side to the image side. The aforementioned rear group consists of a third lens, a fourth lens, a fifth lens, and a sixth lens, in order from the object side towards the image side. If the horizontal field of view is HFOV, the total length between the lenses of the front group is df, and the total length between the lenses of the rear group is dr, then the following conditional expression 100<HFOV (1) df / dr <0.580 (2) An imaging optical system characterized by satisfying the following conditions.
2. If the thickness of the third lens is T3 and the focal length of the entire lens system is f0, then the following conditional equation 1.000< T3 / f0 <2.000 (3) The imaging optical system according to claim 1, characterized in that it satisfies the requirements.
3. The imaging optical system according to claim 1 or 2, characterized in that the third lens has positive power, a concave shape on the object-side lens surface, and a convex shape on the image-side lens surface.
4. The aforementioned third lens is made of glass, If the radius of curvature of the object-side lens surface of the third lens is R31, and the radius of curvature of the image-side lens surface of the third lens is R32, then the following conditional equation 1.000<(R31+R32) / (R31-R32)<1.500 (4) The imaging optical system according to claim 3, characterized in that it satisfies the requirements.
5. If the focal length of the entire lens system is f0 and the focal length of the third lens is f3, then the following conditional equation 1.800< f3 / f0 <4.000 (5) The imaging optical system according to claim 1, characterized in that it satisfies the requirements.
6. If the total length of the lens system is d0, the effective radius of the object-side lens surface of the first lens is sd11, and the maximum image height is IH, then the following conditional equation 3.000<d0 / sd11<5.500 (6) The imaging optical system according to claim 1, characterized in that it satisfies the requirements.
7. If the focal length of the entire lens system is f0 and the total length of the entire lens system is d0, then the following conditional equation 5.500<d0 / f0<9.000 (7) The imaging optical system according to claim 1, characterized in that it satisfies the requirements.
8. If the total length between the lenses of the front group is df and the total length between the lenses of the rear group is dr, The following conditional expression 0.200<df / dr<0.580 (8) The imaging optical system according to claim 1, characterized in that it satisfies the requirements.
9. If the total length of the lens system is d0 and the maximum image height is IH, then the following conditional equation 2.000<d0 / IH<4.000 (9) The imaging optical system according to claim 1, characterized in that it satisfies the requirements.
10. The imaging optical system according to claim 1, The imaging sensor is positioned on the image side of the aforementioned imaging optical system, An imaging device characterized by comprising: