Imaging lens

Abstract

To provide an imaging lens suitable for in-vehicle camera systems, which has a compact configuration, a wide angle of view, a bright optical system with a small F-number, and can accommodate larger image sensors while achieving good resolution performance. [Solution] The lens consists of a first lens having negative refractive power, a second lens having negative refractive power, a third lens having negative refractive power, a fourth lens having positive refractive power, a fifth lens having positive refractive power, a sixth lens having negative refractive power, and a seventh lens having positive refractive power, and is characterized by satisfying the following conditional equation. 1.2 ≤ r1 / r3 ≤ 3.0 ···(1) 0.1 ≤ D12 / r2 ≤ 0.4 ···(2) 1.7 ≤ f7 / f ≤ 2.3 ···(3) 4≦(r3+r2) / (r3-r2)≦4.4···(4)

Description

Technical Field

[0001] The present invention relates to an imaging lens suitable for an in-vehicle camera.

Background Art

[0002] In recent years, technological development related to in-vehicle cameras has been active. For the optical system used in such in-vehicle cameras, it is required to have a short overall lens length and a compact configuration while having a wide angle of view and good resolution performance. Conventionally, a lens unit having a seven-element configuration has been known as an optical system for in-vehicle applications (for example, Patent Document 1, Patent Document 2, and Patent Document 3).

Prior Art Documents

Patent Documents

[0003] [[ID=,22]]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in an in-vehicle camera, it is required to cope with a wide traffic environment, have a high resolution, and have a wide dynamic range so as to be able to acquire information in a scene with a large brightness difference such as backlight or a tunnel entrance / exit. Therefore, the need for using a larger image sensor is increasing.

[0005]

[0006] To satisfy the requirements of these in-vehicle cameras, for the optical system, while maintaining the characteristics of being compact, having a wide angle of view, and having a low F-number, it is required to be compatible with a larger image sensor and have good resolution performance.In particular, even with a wide field of view, a well-balanced, high-quality image is required from the center to the periphery.

[0007] The present invention aims to solve the above-mentioned problems of the conventional invention and achieve the following objectives. Specifically, the present invention aims to provide an imaging lens that has a compact configuration, a wide angle of view and a bright optical system with a small F-number, and that can accommodate larger image sensors and achieve high resolution performance across the entire field of view. [Means for solving the problem]

[0008] The means to solve the above problems are as follows. That is, the imaging lens of the present invention consists of, in order from the object side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having negative refractive power, a fourth lens having positive refractive power, a fifth lens having positive refractive power, a sixth lens having negative refractive power, and a seventh lens having positive refractive power. An imaging lens characterized by satisfying the following conditional equation. 1.2 ≤ r1 / r3 ≤ 3.0 (1) 0.1 ≤ D12 / r2 ≤ 0.4 (2) 1.7 ≤ f7 / f ≤ 2.3 (3) 4 ≤ (r³ + r²) / (r³ - r²) ≤ 4.4 (4) Here, r1 is the radius of curvature of the object-side surface of the first lens. r2 is the radius of curvature of the image-side surface of the first lens. r3 is the radius of curvature of the object-side surface of the second lens. D12 is the air distance on the optical axis between the first and second lenses. f is the focal length of the entire imaging lens system. f7 is the focal length of the 7th lens. That is the case.

[0009] Furthermore, it is preferable that the imaging lens of the present invention satisfies the following conditional equation. 0.7 ≤ f2 / f3 ≤ 1.3 (5) Here, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and they are as follows.

[0010] In addition, in the imaging lens of the present invention, it is preferable to satisfy the following conditional expression. 0.55 ≤ f3 / f1 ≤ 0.595 (6) Here, f1 is the focal length of the first lens, and they are as follows.

Effect of the Invention

[0011] According to the present invention, there is an effect that a compact configuration can provide a bright optical system with a wide angle of view and a small F-number, enabling compatibility with a larger image sensor and high resolution performance over the entire field of view.

Brief Description of the Drawings

[0012] [Figure 1] It is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 1 of the present invention. [Figure 2] It is a diagram showing (A) spherical aberration (AS), (B) distortion (DT), and (C) lateral chromatic aberration (LC) when the imaging lens according to Example 1 is focused at an object distance of 400 mm. [Figure 3] It is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 2 of the present invention. [Figure 4] It is a diagram showing (A) spherical aberration (AS), (B) distortion (DT), and (C) lateral chromatic aberration (LC) when the imaging lens according to Example 2 is focused at an object distance of 400 mm. [Figure 5] It is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 3 of the present invention. [Figure 6] It is a diagram showing (A) spherical aberration (AS), (B) distortion (DT), and (C) lateral chromatic aberration (LC) when the imaging lens according to Example 3 is focused at an object distance of 400 mm. [Figure 7]This is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Embodiment 4 of the present invention. [Figure 8] This figure shows (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration (LC) when the imaging lens according to Example 4 is in focus at an object distance of 400 mm. [Figure 9] This is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Embodiment 5 of the present invention. [Figure 10] This figure shows (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration (LC) when the imaging lens according to Example 5 is in focus at an object distance of 400 mm. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a cross-sectional view along the optical axis showing an example of the optical configuration of an imaging lens according to an embodiment of the present invention. The optical configuration in Figure 1 corresponds to the optical configuration of the first embodiment.

[0014] The imaging lens of the present invention is configured with, in order from the object side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having negative refractive power, a fourth lens having positive refractive power, an aperture diaphragm, a fifth lens having positive refractive power, a sixth lens having negative refractive power, and a seventh lens having positive refractive power. The projection method of the imaging lens of the present invention is an equidistant projection method.

[0015] In all the following embodiments, in the optical configuration cross-sectional diagrams, FL represents various filters such as bandpass filters, CG represents the cover glass, and I represents the imaging surface of the image sensor.

[0016] Furthermore, in the imaging lens of the present invention, it is preferable that the first lens L1 and the fifth lens L5 are both made of glass, and the other lenses are made of plastic, from the viewpoint of low cost and stability of optical performance against changes in ambient temperature.

[0017] An image sensor such as a CCD is arranged on the imaging surface I of the imaging lens of the present invention. A dual bandpass filter FL is arranged in the space between the seventh lens L7 and the cover glass CG, having transmission areas in both the visible light region and the near-infrared light region, enabling continuous day and night imaging.

[0018] Furthermore, the imaging lens used in this implementation satisfies the following condition. 1.2 ≤ r1 / r3 ≤ 3.0 (1) 0.1 ≤ D12 / r2 ≤ 0.4 (2) 1.7 ≤ f7 / f ≤ 2.3 (3) 4 ≤ (r³ + r²) / (r³ - r²) ≤ 4.4 (4) Here, r1 is the radius of curvature of the object-side surface of the first lens. r2 is the radius of curvature of the image-side surface of the first lens. r3 is the radius of curvature of the object-side surface of the second lens. D12 is the air distance on the optical axis between the first and second lenses. f is the focal length of the entire imaging lens system. f7 is the focal length of the 7th lens. That is the case.

[0019] Conditional equations (1) and (2) are conditions for achieving a wide-angle optical system while increasing the peripheral illumination ratio, ensuring the illumination ratio in the peripheral areas without increasing the sensor gain, and obtaining a well-balanced, high-quality image even at the edges. If the range exceeds that of conditional equation (1), the radius of curvature of the object-side surface of the second lens L2 becomes too small, making it difficult to ensure resolution while maintaining the illumination ratio. Conversely, if the range falls below that of conditional equation (1), the radius of curvature of the object-side surface of the first lens L1 becomes too small, similarly making it difficult to maintain the illumination ratio. If the range exceeds that of condition (2), the distance between L1 and L2 becomes too long, making it difficult to maintain the light intensity ratio. Conversely, if the range falls below that of condition (2), the radius of curvature of the image-side surface of the first lens L1 becomes too large, also making it difficult to maintain the light intensity ratio.

[0020] Condition (3) is a condition that increases the distance along the optical axis from the image-side surface of the seventh lens L7 to the image plane (back focus), thereby increasing the telecentricity of the light emitted from the seventh lens and preventing image quality degradation in the peripheral areas without increasing the sensor gain. If the range exceeds that of condition (3), the back focus becomes too large, making it difficult to miniaturize the optical system, which is undesirable. Conversely, if the range falls below that of condition (3), the angle of incidence to the image sensor becomes too large, which is undesirable from the standpoint of ensuring a proper peripheral illumination ratio.

[0021] Conditional equation (4) is a conditional equation for correcting field curvature aberration well while ensuring the peripheral illumination ratio. If the range exceeds that of conditional equation (4), the radius of curvature of the object-side surface of the second lens becomes too large, making it difficult to correct field curvature aberration, which is undesirable. Conversely, if the range falls below that of conditional equation (4), the radius of curvature of the image-side surface of the first lens becomes too large, similarly making it difficult to correct field curvature aberration and ensuring resolution, which is also undesirable.

[0022] Furthermore, the imaging lens of this embodiment more preferably satisfies the following conditional expression. 0.7 ≤ f2 / f3 ≤ 1.3 (5) Here, f2 is the focal length of the second lens. f3 is the focal length of the third lens. That is the case.

[0023] Condition (5) is a condition for obtaining a well-balanced, high-quality image even at the edges by making the power of the second and third lenses as equal as possible, thereby mitigating error sensitivity. If the range falls below that of condition (5), the lens power of the second and third lenses becomes uneven, which is undesirable from the standpoint of aberration correction. Conversely, if the range exceeds that of condition (5), the negative refractive power of the second lens becomes too strong, making it difficult to correct field curvature aberration, which is undesirable from the standpoint of ensuring resolution.

[0024] Furthermore, the imaging lens of this embodiment more preferably satisfies the following conditional expression. 0.55 ≤ f3 / f1 ≤ 0.595 (6) Here, f1 is the focal length of the first lens. That is the case. Conditional equation (6) is a conditional equation for effectively correcting field curvature aberration. If the range exceeds that of conditional equation (6), the negative refractive power of the third lens becomes too large, making it difficult to correct field curvature aberration, which is undesirable. Conversely, if the range falls below that of conditional equation (6), the negative refractive power of the first lens becomes too large, similarly making it difficult to correct field curvature aberration, which is undesirable from the standpoint of ensuring resolution. [Examples]

[0025] Next, specific numerical examples of the imaging lens of the present invention are shown. The symbols used in each example are as follows.

[0026] f: Focal length of the entire imaging lens system (Effective Focal Length) FNO: F-number TTL: Optical total length r: paraxial radius of curvature d(D): Thickness of the lens or air gap on the optical axis nd: Refractive index of lens material relative to the d line νd: Abbe number of lens material Φimg: Image circle of the imaging lens Furthermore, in each embodiment, the surfaces marked with an asterisk (*) after each surface number are surfaces with an aspherical shape.

[0027] Furthermore, the aspherical shape is expressed by the following equation (I), where z is the direction of the optical axis, y is the direction perpendicular to the optical axis, K is the conicity coefficient, and A4, A6, A8, A10... are the aspherical coefficients. z=(y 2 / r) / [1+{1-(1+K)(y / r) 2} 1 / 2 ]+A4y 4 +A6y 6 +A8y 8 +A10y 10 ...(I) In the aspherical coefficient, E represents a power of 10, for example, 2.3 × 10⁻⁶. -2 This shall be represented as 2.3E-002. Furthermore, the symbols for these specifications are the same in the numerical data of the examples described later.

[0028] (Example 1) Next, the imaging lens according to Example 1 will be described. Figure 1 is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 1.

[0029] Figure 2 shows the (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration (LC) of the imaging lens according to Example 1 when the object distance is 400 mm and in focus. The vertical axis in the graph represents the image height. The symbols and conditions in the aberration diagram are the same as those in the examples described later.

[0030] As shown in Figure 1, this imaging lens consists of, in order from the object side, a negative meniscus first lens L1 with a convex surface facing the object side, a negative meniscus second lens L2 with a convex surface facing the object side, a third lens L3 with negative refractive power and a concave surface facing both the object and image sides, a fourth lens L4 with positive refractive power and a convex surface facing both the object and image sides, an aperture diaphragm S, a fifth lens L5 with positive refractive power and a convex surface facing both the object and image sides, a sixth lens L6 with negative refractive power and a concave surface facing both the object and image sides, and a seventh lens L7 with positive refractive power and a convex surface facing both the object and image sides.

[0031] The overall specifications of the imaging lens in Example 1 are shown below. f: 0.960mm f1: -6.993mm f2 : -3.498mm f3 : -4.037mm f4: 3.506mm f5: 2.267mm f6 : -1.504mm f7: 1.867mm FNO: 1.81 TTL: 13.186mm Φimg: 1.962mm Table 1 shows the surface data of the imaging lens for Example 1. The upper row of Table 1 shows the central radius of curvature (r), thickness (d), refractive index (nd), and Abbe number (νd) for each surface, with the central radius of curvature and thickness in mm. These symbols are also common to the numerical data of the examples described later.

[0032] [Table 1]

[0033] The aspherical data of the imaging lens in Example 1 is shown below. 3rd page K = -3.351422E+01 A4=5.866161E-03, A6=4.042921E-05, A8=-1.621422E-06, A10=3.943704E-07 Side 4 K = -5.736377E-01 A4=-3.833040E-02, A6= 7.576225E-03, A8=-3.795317E-03, A10=1.505090E-03, A12=-3.160280E-04 5th page K=-6.374493E-04 A4=-2.638043E-03, A6= 6.267440E-03, A8=1.403894E-03, A10=-5.213729E-04 Side 6 K=0 A4=1.107251E-02, A6=-2.223835E-03, A8=4.307368E-03 Side 7 K=0 A4=-1.137750E-02, A6= -3.645498E-03, A8=-1.067422E-03 Side 8 K=0 A4=-1.424203E-02, A6=1.465463E-02, A8=-1.061963E-02 9th page K=0 A4=-2.939246E-02, A6= 1.122343E-02 Side 10 K=0 A4=1.371149E-02, A6=4.001783E-03 Page 11 K=0 A4=4.719971E-02, A6=-1.812801E-02, A8=2.740279E-03, A10=-9.817858E-03 Side 12 K=0 A4=-1.012966E-01, A6= 8.344144E-02, A8=-3.866353E-02, A10=3.447496E-03 Page 13 K = -8.380571E+00 A4=-5.159014E-02, A6= 6.277990E-02, A8=-2.288225E-02, A10=3.659743E-03 Page 14 K = -9.370148E-01 A4=1.558372E-03, A6=1.363513E-02, A8=-1.314025E-02, A10=5.786708E-03

[0034] The values ​​corresponding to the conditional equations (1) to (6) for the imaging lens in Example 1 are shown below. (1) r1 / r3 = 2.188 (2) D12 / r2 = 0.369 (3) f7 / f=1.945 (4)(r3+r2) / (r3-r2)=4.050 (5) f2 / f3 = 0.866 (6) f3 / f1 = 0.577 In the imaging lens of Example 1, the first and fifth lenses are made of glass material, while the other lenses are made of plastic material.

[0035] (Example 2) Next, we will describe the imaging lens according to Example 2. Figure 3 is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 2.

[0036] As shown in Figure 3, this imaging lens consists of, in order from the object side, a negative meniscus first lens L1 with a convex surface facing the object side, a negative meniscus second lens L2 with a convex surface facing the object side, a third lens L3 with negative refractive power with a concave surface facing both the object and image sides, a fourth lens L4 with positive refractive power with a convex surface facing both the object and image sides, an aperture diaphragm S, a fifth lens L5 with positive refractive power with a convex surface facing both the object and image sides, a sixth lens L6 with negative refractive power with a concave surface facing both the object and image sides, and a seventh lens L7 with positive refractive power with a convex surface facing both the object and image sides.

[0037] The overall specifications of the imaging lens in Example 2 are shown below. f: 0.978mm f1: -7.002mm f2 : -3.525mm f3 : -4.024mm f4: 3.501mm f5: 2.273mm f6 : -1.505mm f7: 1.879mm FNO: 1.850 TTL: 13.196mm Φimg: 1.959mm The surface data of the imaging lens in Example 2 is shown below.

[0038] [Table 2]

[0039] The aspherical data of the imaging lens in Example 2 is shown below. Page 3 K = -3.038745E+01 A4=5.352133E-03, A6=5.871111E-06, A8=-2.157444E-06, A10=6.006206E-07 Page 4 K=-5.819506E-01 A4=-3.780256E-02, A6=7.549362E-03, A8=-3.781389E-03, A10=1.512174E-03, A12=-3.145950E-04 Page 5 K=4.274694E-02 A4=-3.083507E-03, A6=6.147332E-03, A8=1.386398E-03, A10=-5.052077E-04 Page 6 K=0 A4=1.171786E-02, A6=-2.273563E-03, A8=4.318668E-03 Page 7 K=0 A4=-1.185158E-02, A6=-3.640416E-03, A8=-8.534562E-04 Page 8 K=0 A4=-1.605259E-02, A6=1.356117E-02, A8=-8.497069E-03 Page 9 K=0 A4=-2.698497E-02, A6=1.058969E-02 Page 10 K=0 A4=1.379041E-02, A6=3.629690E-03 Page 11 K=0 A4=4.750625E-02, A6=-1.718933E-02, A8=4.099819E-03, A10=-8.857168E-03 Page 12 K=0 A4=-1.014827E-01, A6=8.343613E-02, A8=-3.842131E-02, A103.902459E-03 Page 13 K = -8.444112E + 00 A4=-5.153500E-02, A6=6.284730E-02, A8=-2.284574E-02, A10=3.676321E-03 Page 14 K = -9.391161E-01 A4=1.659111E-03, A6=1.351586E-02, A8=-1.317135E-02, A10=5.785139E-03

[0040] The values ​​corresponding to the conditional equations (1) to (6) for the imaging lens in Example 2 are shown below. (1) r1 / r3 = 2.190 (2) D12 / r2 = 0.367 (3) f7 / f=1.921 (4)(r3+r2) / (r3-r2)=4.001 (5) f2 / f3 = 0.876 (6) f3 / f1 = 0.575 In the imaging lens of Example 2, the first and fifth lenses are made of glass material, while the other lenses are made of plastic material.

[0041] (Example 3) Next, we will describe the imaging lens according to Example 3. Figure 5 is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 3.

[0042] As shown in Figure 5, this imaging lens consists of, in order from the object side, a negative meniscus first lens L1 with a convex surface facing the object side, a negative meniscus second lens L2 with a convex surface facing the object side, a third lens L3 with negative refractive power with a concave surface facing both the object and image sides, a fourth lens L4 with positive refractive power with a convex surface facing both the object and image sides, an aperture diaphragm S, a fifth lens L5 with positive refractive power with a convex surface facing both the object and image sides, a sixth lens L6 with negative refractive power with a concave surface facing both the object and image sides, and a seventh lens L7 with positive refractive power with a convex surface facing both the object and image sides.

[0043] The overall specifications of the imaging lens in Example 3 are shown below. f: 1.018mm f1: -7.191mm f2 : -3.464mm f3 : -4.013mm f4 : 3.495mm f5: 2.263mm f6 : -1.504mm f7: 1.914mm FNO: 1.928 TTL: 13.192mm Φimg: 1.964mm The surface data of the imaging lens in Example 3 is shown below.

[0044] [Table 3]

[0045] The aspherical data of the imaging lens in Example 3 is shown below. 3rd page K = -2.981891E+01 A4=4.788675E-03, A6=-2.015030E-05, A8=-2.302649E-06, A10=1.409382E-06 Side 4 K=-5.696389E-01 A4=-3.299291E-02, A6=6.803197E-03, A8=-4.077658E-03, A10=1.502377E-03, A12=-2.831473E-04 Page 5 K=2.658471E-02 A4=-3.261680E-03, A6=6.298598E-03, A8=1.449903E-03, A10=-4.537401E-04 Page 6 K=0 A4=1.050563E-02, A6=-2.689944E-03, A8=4.583010E-03 Page 7 K=0 A4=-1.333728E-02, A6=-4.105275E-03, A8=-1.369185E-03 Page 8 K=0 A4=-1.682038E-02, A6=1.113480E-02, A8=-6.074780E-03 Page 9 K=0 A4=-2.123582E-02, A6=1.554062E-02 Page 10 K=0 A4=1.416898E-02, A6=7.867935E-03 Page 11 K=0 A4=4.529633E-02, A6=-2.249405E-02, A8=3.856871E-03, A10=-7.372772E-03 Page 12 K=0 A4=-1.020187E-01, A6=8.257525E-02, A8=-3.884674E-02, A10=4.583457E-03 Page 13 K = -8.245032E + 00 A4=-5.148258E-02, A6=6.303345E-02, A8=-2.277986E-02, A10=3.634584E-03 Page 14 K = -9.212671E-01 A4=1.089627E-03, A6=1.348192E-02, A8=-1.317279E-02, A10=5.737670E-03

[0046] The values ​​corresponding to the conditional equations (1) to (6) for the imaging lens in Example 3 are shown below. (1) r1 / r3 = 2.229 (2) D12 / r2 = 0.363 (3) f7 / f=1.881 (4)(r3+r2) / (r3-r2)=4.400 (5) f2 / f3 = 0.863 (6) f3 / f1 = 0.558 In the imaging lens of Example 3, the first and fifth lenses are made of glass material, while the other lenses are made of plastic material.

[0047] (Example 4) Next, we will describe the imaging lens according to Example 4. Figure 7 is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 4.

[0048] As shown in Figure 7, this imaging lens consists of, in order from the object side, a negative meniscus first lens L1 with a convex surface facing the object side, a negative meniscus second lens L2 with a convex surface facing the object side, a third lens L3 with negative refractive power with a concave surface facing both the object and image sides, a fourth lens L4 with positive refractive power with a convex surface facing both the object and image sides, an aperture diaphragm S, a fifth lens L5 with positive refractive power with a convex surface facing both the object and image sides, a sixth lens L6 with negative refractive power with a concave surface facing both the object and image sides, and a seventh lens L7 with positive refractive power with a convex surface facing both the object and image sides.

[0049] The overall specifications of the imaging lens in Example 4 are shown below. f: 0.962mm f1: -6.660mm f2 : -3.236mm f3 : -3.969mm f4: 3.462mm f5: 2.241mm f6 : -1.515mm f7: 1.924mm FNO: 1.928 TTL: 13.194mm Φimg: 1.963mm The surface data of the imaging lens in Example 4 is shown below.

[0050] [Table 4]

[0051] The aspherical data for the imaging lens of Example 4 is shown below. 3rd page K = -3.574357E + 00 A4=3.933462E-03, A6=-1.401145E-04, A8=-3.580714E-07, A10=3.356557E-06 Side 4 K=-5.623034E-01 A4=-2.416116E-02, A6=7.141982E-03, A8=-5.240284E-03, A10=1.226876E-03, A12=-2.970413E-04 5th page K=5.901074E-02 A4=-3.353581E-03, A6=6.145339E-03, A8=1.376579E-03, A10=-4.333248E-04 Side 6 K=0 A4=1.302296E-02, A6=-2.855645E-03, A8=5.108161E-03 Side 7 K=0 A4=-1.515237E-02, A6=-4.078635E-03, A8=-1.650463E-03 Side 8 K=0 A4=-1.709944E-02, A6=8.569259E-03, A8=-3.712223E-03 9th page K=0 A4=-2.168937E-02, A6=1.835350E-02 Side 10 K=0 A4=1.449803E-02, A6=7.510463E-03 Page 11 K=0 A4=4.305068E-02, A6=-2.641551E-02, A8=3.288989E-03, A10=-8.281769E-03 Side 12 K=0 A4=-1.019837E-01, A6=8.234496E-02, A8=-3.917153E-02, A10=4.744344E-03 Page 13 K = -8.159181E+00 A4=-5.184304E-02, A6=6.302540E-02, A8=-2.272776E-02, A10=3.650348E-03 Page 14 K = -9.210122E-01 A4=1.176030E-03, A6=1.320182E-02, A8=-1.315916E-02, A10=5.763708E-03

[0052] The values ​​corresponding to the conditional equations (1) to (6) for the imaging lens in Example 4 are shown below. (1) r1 / r3 = 2.319 (2) D12 / r2 = 0.386 (3) f7 / f=2.000 (4)(r3+r2) / (r3-r2)=4.391 (5) f2 / f3 = 0.815 (6) f3 / f1 = 0.596 In the imaging lens of Example 4, the first and fifth lenses are made of glass material, while the other lenses are made of plastic material.

[0053] (Example 5) Next, we will describe the imaging lens according to Example 5. Figure 9 is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 5.

[0054] As shown in Figure 9, this imaging lens consists of, in order from the object side, a negative meniscus first lens L1 with a convex surface facing the object side, a negative meniscus second lens L2 with a convex surface facing the object side, a third lens L3 with negative refractive power with a concave surface facing both the object and image sides, a fourth lens L4 with positive refractive power with a convex surface facing both the object and image sides, an aperture diaphragm S, a fifth lens L5 with positive refractive power with a convex surface facing both the object and image sides, a sixth lens L6 with negative refractive power with a concave surface facing both the object and image sides, and a seventh lens L7 with positive refractive power with a convex surface facing both the object and image sides.

[0055] The overall specifications of the imaging lens in Example 5 are shown below. f: 0.944mm f1: -7.107mm f2 : -3.147mm f3: -3.913mm f4: 3.462mm f5: 2.239mm f6 : -1.516mm f7: 1.918mm FNO: 1.921 TTL: 13.193mm Φimg: 1.962mm The surface data of the imaging lens in Example 5 is shown below.

[0056] [Table 5]

[0057] The aspherical data of the imaging lens in Example 5 is shown below. 3rd page K = -4.341783E + 00 A4=3.807244E-03, A6=-1.559370E-04, A8=-2.645373E-06, A10=3.181636E-06 Side 4 K = -5.622177E-01 A4=-2.363117E-02, A6=6.991843E-03, A8=-5.260537E-03, A10=1.221074E-03, A12=-2.974847E-04 5th page K=5.719272E-02 A4=-3.325034E-03, A6=6.148690E-03, A8=1.376975E-03, A10=-4.339350E-04 Side 6 K = 0 A4=1.296246E-02, A6=-2.886298E-03, A8=5.094858E-03 Side 7 K=0 A4=-1.516118E-02, A6=-4.101702E-03, A8=-1.677738E-03 Side 8 K=0 A4=-1.694961E-02, A6=8.715930E-03, A8=-3.815160E-03 9th page K=0 A4=-2.186098E-02, A6=1.809478E-02 Side 10 K = 0 A4=1.444478E-02, A6=7.531574E-03 Page 11 K=0 A4=4.323717E-02, A6=-2.626137E-02, A8=3.286268E-03, A10=-8.094945E-03 Side 12 K=0 A4=-1.020042E-01, A6=8.239171E-02, A8=-3.913237E-02, A10=4.735380E-03 Page 13 K = -8.155876E + 00 A4=-5.185324E-02, A6=6.301116E-02, A8=-2.273140E-02, A10=3.654265E-03 Page 14 K = -9.186817E-01 A4=1.105682E-03, A6=1.319666E-02, A8=-1.315511E-02, A10=5.768473E-03

[0058] The values ​​corresponding to the conditional equations (1) to (6) for the imaging lens in Example 5 are shown below. (1) r1 / r3 = 2.152 (2) D12 / r2 = 0.363 (3) f7 / f=1.881 (4)(r3+r2) / (r3-r2)=4.001 (5) f2 / f3 = 0.804 (6) f3 / f1=0.551 In the imaging lens of Example 5, the first and fifth lenses are made of glass material, while the other lenses are made of plastic material. [Explanation of symbols]

[0059] L1 First Lens L2 Second Lens L3 3rd lens L4 4th lens L5 5th lens L6 6th lens L7 7th lens FL bandpass filter (dual-pass filter) CG cover glass I. Imaging surface S Aperture diaphragm

Claims

1. From the object side, the lens consists of, in order: a first lens with negative refractive power, a second lens with negative refractive power, a third lens with negative refractive power, a fourth lens with positive refractive power, a fifth lens with positive refractive power, a sixth lens with negative refractive power, and a seventh lens with positive refractive power. An imaging lens characterized by satisfying the following conditional equation. 1.2 ≤ r1 / r3 ≤ 3.0 (1) 0.1 ≤ D12 / r2 ≤ 0.4 (2) 1.7 ≤ f7 / f ≤ 2.3 (3) 4≦(r3+r2) / (r3-r2)≦4.4 (4) Here, r1 is the radius of curvature of the object-side surface of the first lens. r2 is the radius of curvature of the image-side surface of the first lens. r3 is the radius of curvature of the object-side surface of the second lens. D12 is the air distance on the optical axis between the first lens and the second lens. f is the focal length of the entire imaging lens system. f7 is the focal length of the seventh lens. That is the case.

2. The imaging lens according to claim 1, characterized in that it satisfies the following conditional expression. 0.7 ≤ f² / f³ ≤ 1.3 (5) Here, f2 is the focal length of the second lens. f3 is the focal length of the third lens. That is the case.

3. The imaging lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression. 0.55 ≤ f3 / f1 ≤ 0.595 (6) Here, f1 is the focal length of the first lens. That is the case.

Images