Imaging lens

Abstract

Provided is an imaging lens suitable for a vehicle-mounted camera device, the imaging lens being a bright optical system having a wide angle of view and a small F number despite having a compact configuration, and capable of supporting a larger image sensor and obtaining good resolution performance. This imaging lens is characterized by comprising, in order from the object side: a first lens having negative refractive power; a second lens having negative refractive power; a third lens having positive refractive power; a fourth lens having positive refractive power; a fifth lens having negative refractive power; and a sixth lens having positive refractive power, and satisfying the following conditional expressions. (1): -6.3 < f2 / f < -3; (2): 3.4 < r1 / r2 < 5.6; (3): 3.0 < r10 / D56 < 24; (4): 0.5 < D34 / f < 2.1

Description

Imaging lens

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

[0002] In recent years, technological development related to in-vehicle cameras has become active. The optical systems used in such in-vehicle cameras are required to have a short overall lens length, a bright optical system with a wide angle of view and a small F-number, and good resolution performance. Six-lens lens units have been known as in-vehicle optical systems (see, for example, Patent Documents 1, 2, and 3).

[0003] Japanese Patent No. 5795379 Japanese Patent Application Laid-Open No. 2007-279632 Japanese Patent Application Laid-Open No. 2018-55045

[0004] Meanwhile, vehicle-mounted cameras are required to be able to handle a wide range of traffic environments, and are required to have high resolution as well as a wide dynamic range to enable the acquisition of information in scenes with large differences in light and dark, such as backlighting and tunnel entrances and exits. As a result, there is a growing need for larger image sensors.

[0005] To satisfy these requirements for vehicle-mounted cameras, the optical system must maintain its compact size, wide angle of view, and low F-number, while also being compatible with larger image sensors and providing good resolution.

[0006] The present invention aims to solve the above-mentioned problems in the prior art and achieve the following object: That is, the present invention aims to provide an imaging lens that is a bright optical system with a wide angle of view and a small F-number, while having a compact configuration, and that is compatible with larger image sensors and provides good resolution performance.

[0007] The imaging lens according to claim 1 comprises, in order from the object side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having positive refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power, and is characterized in that the imaging lens satisfies the following conditional expression: -6.3<f2 / f<-3 (1) 3.4<r1 / r2<5.6 (2) 3.0<r10 / D56<24 (3) 0.5<D34 / f<2.1 (4) Here, f is the focal length of the entire imaging lens system, f2 is the focal length of the second lens, 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, r10 is the radius of curvature of the image-side surface of the fifth lens, D56 is the air spacing on the optical axis between the fifth lens and the sixth lens, and D34 is the air spacing on the optical axis between the third lens and the fourth lens.

[0008] The imaging lens described in claim 2 is the imaging lens described in claim 1, and preferably satisfies the following conditional expression: −17<f123 / f<−5 (5) where f123 is the combined focal length of the first, second and third lenses.

[0009] The imaging lens described in claim 3 is the imaging lens described in claim 1 or claim 2, and preferably satisfies the following condition: 0.5<r10 / r11<1.3 (6) where r11 is the radius of curvature of the object-side surface of the sixth lens.

[0010] The imaging lens described in claim 4 is the imaging lens described in claim 2, wherein it is preferable that the object-side surface of the third lens is a concave surface.

[0011] An imaging lens described in claim 5 is the imaging lens described in claim 3, and preferably satisfies the following conditional expression: 0.01<D45 / f<0.2 (7) where D45 is the air gap between the fourth lens and the fifth lens on the optical axis.

[0012] According to the present invention, a bright optical system with a wide angle of view and a small F-number can be provided, while still having a compact configuration, and it is possible to achieve compatibility with larger image sensors and good resolution performance.

[0013] FIG. 1 is a cross-sectional view taken along the optical axis showing the optical configuration of an imaging lens according to Example 1 of the present invention. FIG. 2 is a diagram showing (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration of magnification (LC) of the imaging lens according to Example 1 when focused at an object distance of 400 mm. FIG. 3 is a cross-sectional view taken along the optical axis showing the optical configuration of an imaging lens according to Example 2 of the present invention. FIG. 4 is a diagram showing (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration of magnification (LC) of the imaging lens according to Example 2 when focused at an object distance of 400 mm. FIG. 5 is a cross-sectional view taken along the optical axis showing the optical configuration of an imaging lens according to Example 3 of the present invention. FIG. 6 is a diagram showing (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration of magnification (LC) of the imaging lens according to Example 3 when focused at an object distance of 400 mm. FIG. 7 is a cross-sectional view taken along the optical axis showing the optical configuration of an imaging lens according to Example 4 of the present invention. 10A and 10B are diagrams showing (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration of magnification (LC) of the imaging lens according to Example 4 when focused at an object distance of 400 mm. FIG. 10B is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 5 of the present invention. FIG. 10C is a diagram showing (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration of magnification (LC) of the imaging lens according to Example 5 when focused at an object distance of 400 mm. FIG. 10C is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 6 of the present invention. FIG. 10D is a diagram showing (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration of magnification (LC) of the imaging lens according to Example 6 when focused at an object distance of 400 mm. FIG. 10E is a cross-sectional view along the optical axis showing the optical configuration of the imaging lens according to Example 7 of the present invention. 10A and 10B are diagrams showing (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration of magnification (LC) of the imaging lens according to Example 7 when focused at an object distance of 400 mm.

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view taken 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 Fig. 1 corresponds to the optical configuration of the first example.

[0015] The imaging lens of the present invention comprises, arranged in order from the object side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, an aperture stop, a fourth lens having positive refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power.

[0016] In all the following examples, in the cross-sectional views of the optical configuration, FL denotes various filters such as a band-pass filter, CG denotes a cover glass, and I denotes an imaging surface of an imaging element.

[0017] Furthermore, in the imaging lens of the present invention, it is preferable that the first lens L1 and the fourth lens L4 are both made of glass, and the other lenses are made of plastic, from the viewpoints of low cost and optical performance stability against changes in environmental temperature.

[0018] An imaging element such as a CCD is disposed on the imaging surface I of the imaging lens of the present invention. A dual band-pass filter FL, which has transmission bands in both the visible light region and the near-infrared light region and enables continuous day and night imaging, is disposed in the space between the sixth lens L6 and the cover glass CG.

[0019] The imaging lens of this embodiment also satisfies the following conditional expressions: -6.3<f2 / f<-3 (1) 3.4<r1 / r2<5.6 (2) 3.0<r10 / D56<24 (3) 0.5<D34 / f<2.1 (4) where f is the focal length of the entire imaging lens system, f2 is the focal length of the second lens, 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, r10 is the radius of curvature of the image-side surface of the fifth lens, D56 is the air spacing on the optical axis between the fifth and sixth lenses, and D34 is the air spacing on the optical axis between the third and fourth lenses.

[0020] Conditional expression (1) is a conditional expression for realizing a compact, wide-angle optical system while shortening the overall length of the optical system. If the range of conditional expression (1) is exceeded, the power of the second lens becomes too strong, which is disadvantageous for shortening the overall length of the optical system. Also, if the range of conditional expression (1) is exceeded, positive distortion becomes strong, forming a narrow angle with respect to the sensor, making it impossible to effectively utilize the sensor area.

[0021] Conditional expression (2) is a conditional expression for achieving a wide-angle optical system while satisfactorily correcting coma and chromatic aberration. If the range of conditional expression (2) is exceeded, the radius of curvature on the object side of the first lens becomes too large, which makes the angle of incidence of light rays from a wide angle of view steep, making it difficult to allow light rays to enter at 90 degrees or more, which is undesirable. Furthermore, if the range of conditional expression (2) is exceeded, the radius of curvature on the image side of the first lens becomes too large, which prevents light beam separation at each angle of view from the second lens onward from becoming small, making it difficult to correct coma and chromatic aberration thereafter, which is undesirable.

[0022] Conditional expression (3) is a conditional expression for ensuring an image circle while shortening the overall length of the optical system. If the range of conditional expression (3) is exceeded, the radius of curvature on the image side of the fifth lens becomes large and the positive power becomes strong, resulting in strong negative distortion, making it difficult to increase the image circle and shortening the back focus, which is undesirable. If the range of conditional expression (3) is exceeded, the air gap on the optical axis between the fifth lens and the sixth lens becomes too large, which is undesirable from the perspective of shortening the overall length of the optical system.

[0023] Conditional expression (4) is a conditional expression for effectively correcting lateral chromatic aberration while shortening the overall length of the optical system. If the range of conditional expression (4) is exceeded, the air gap becomes too large, which is undesirable from the viewpoint of shortening the overall length of the optical system. If the range of conditional expression (4) is exceeded, the difference between the peripheral angle of view and the on-axis optical path becomes small, which is undesirable because it makes it difficult to correct lateral chromatic aberration.

[0024] Furthermore, the imaging lens of this embodiment more preferably satisfies the following conditional expression: -17<f123 / f<-5 (5) where f123 is the combined focal length of the first, second and third lenses.

[0025] Conditional expression (5) is a conditional expression for achieving a wide angle of view of the optical system while satisfactorily correcting curvature of field and chromatic aberration. If the range of conditional expression (5) is not satisfied, the negative refractive power of the first lens and the second lens will be too weak, making it difficult to achieve a wide angle of view. If the range of conditional expression (5) is exceeded, the negative refractive power of the first lens and the second lens will be too strong, making it difficult to correct curvature of field, and the positive refractive power of the third lens will be too weak, making it difficult to correct chromatic aberration, both of which are undesirable.

[0026] Furthermore, the imaging lens of this embodiment more preferably satisfies the following conditional expression: 0.5<r10 / r11<1.3 (6) where r11 is the radius of curvature of the object-side surface of the sixth lens.

[0027] Conditional expression (6) is a conditional expression for ensuring the image circle while correcting the curvature of field. If the range of conditional expression (6) is not satisfied, the radius of curvature of the image-side surface of the fifth lens becomes too small, which undesirably increases the curvature of field. If the range of conditional expression (6) is exceeded, the radius of curvature of the object-side surface of the sixth lens becomes too small, which undesirably increases negative distortion and makes it difficult to increase the image circle.

[0028] Furthermore, in the imaging lens of this embodiment, it is more preferable that the object-side surface of the third lens is concave. By making the object-side surface of the third lens concave, the periphery of the object-side surface of the second lens can be made convex. This makes it possible to strengthen the positive power at the periphery of the second lens, thereby preventing the peripheral light flux from becoming thin and preventing a decrease in the peripheral illumination ratio.

[0029] Furthermore, the imaging lens of this embodiment more preferably satisfies the following conditional expression: 0.01<D45 / f<0.2 (7) where D45 is the air gap between the fourth lens and the fifth lens on the optical axis.

[0030] Conditional expression (7) is a conditional expression for effectively correcting chromatic aberration while shortening the overall length of the optical system. If the range of conditional expression (7) is exceeded, the air gap on the optical axis between the fourth lens and the fifth lens becomes too large, making it difficult to shorten the overall optical length. If the range of conditional expression (7) is exceeded, the air gap on the optical axis between the fourth lens and the fifth lens becomes too small, making it difficult to keep the sensitivity of the optical system to manufacturing errors low, which is undesirable.

[0031] Next, specific numerical examples of the imaging lens of the present invention will be shown. The symbols used in each example are as follows.

[0032] f: Focal length of the entire imaging lens system (effective focal length) FNO: F-number TTL: Total optical length r: Paraxial radius of curvature d(D): Lens thickness or air space on the optical axis nd: Refractive index of the lens material for the d-line νd: Abbe number of the lens material Φimg: Image circle of the imaging lens In addition, in each example, surfaces with an "*" after the surface number are surfaces having an aspherical shape.

[0033] The aspherical shape is expressed by the following formula (I): 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 coefficients, E represents a power of 10, for example, 2.3×10 －２ is expressed as 2.3E-002. The symbols for these specification values ​​are also common to the numerical data in the examples described later. The symbols for these specification values ​​are also common to the numerical data in the examples described later.

[0034] Next, a description will be given of an imaging lens according to Example 1. Fig. 1 is a cross-sectional view taken along the optical axis and showing the optical configuration of the imaging lens according to Example 1.

[0035] 2A and 2B are diagrams showing (A) astigmatism (AS), (B) distortion (DT), and (C) chromatic aberration of magnification (LC) of the imaging lens according to Example 1 when focused at an object distance of 400 mm. The vertical axis in the graphs indicates image height. Note that the symbols and conditions in the aberration diagrams are common to the examples described below.

[0036] As shown in FIG. 1, this imaging lens is composed of, in order from the object side, a negative meniscus first lens L1 with a convex surface facing the object side, a second lens L2 with a concave surface facing the object side and the image side and having negative refractive power, a positive meniscus third lens L3 with a concave surface facing the object side, an aperture stop S, a fourth lens L4 with a convex surface facing the object side and the image side and having positive refractive power, a fifth lens L5 with a concave surface facing the object side and the image side and having negative refractive power, and a sixth lens L6 with a convex surface facing the object side and the image side and having positive refractive power.

[0037] The overall specifications of the imaging lens of Example 1 are as follows: f: 0.92 mm f1: -5.662 mm f2: -3.067 mm f3: 5.779 mm f4: 2.614 mm f5: -1.837 mm f6: 1.947 mm FNO: 2.00 TTL: 13.116 mm Φimg: 3.944 mm

[0038] Table 1 shows the surface data of the imaging lens of Example 1. The upper row of Table 1 shows the central radius of curvature (r), thickness (d), refractive index (nd), and Abbe number (νd) of each surface, with the units of the central radius of curvature and thickness being mm. These symbols are also used in the numerical data of the examples described below.

[0039]

[0040] The aspherical data of the imaging lens of Example 1 is shown below. 3rd side K=0 A4=5.537E-02, A6=-1.494E-02, A8=1.726E-03, A10= -7.099E-05, A12=-6.034E-08, A14=-2.713E-08 4th side K=0 A4=3.491E-02, A6=4.698E-02, A8=-5.070E-02, A10=1.281E-02, A12=-1.107E-03, A14=1.669E-05 5th side K=0 A4= -4.494E-03, A6= -2.502E-02, A8= 9.161E-03, A10=-1.272E-03, A12= 1.310E-04 6th side K=0 A4= -1.459E-02, A6= 1.174E-02, A8= -6.855E-03, A10=4.467E-03, A12=-1.521E-03, A14= 1.313E-04 7th side K=0 A4=-2.422E-02, A6=2.478E-02, A8=-3.264E-02 8th side K=0 A4=-1.423E-02, A6=1.880E-02, A8=-1.204E-03 9th side K=0 A4=-1.478E-01, A6=1.454E-01, A8= -7.134E-02, A10=2.054E-02, A12=1.164E-03 10th side K=0 A4=-1.744E-01, A6=8.799E-02, A8=-2.753E-02, A10=1.201E-03, A12=-1.056E-05 11th side K=0 A4= -8.196E-02, A6= 3.201E-02, A8= -4.380E-03, A10= 6.454E-04, A12= -1.646E-04 12th side K=0 A4= 5.020E-02, A6= -4.370E-03, A8= 2.601E-02, A10= -1.461E-02, A12= 4.345E-03

[0041] The values ​​corresponding to conditional expressions (1) to (7) of the imaging lens of Example 1 are as follows: (1) f2 / f = -3.349 (2) r1 / r2 = 4.566 (3) r10 / D56 = 16.331 (4) D34 / f = 0.860 (5) f123 / f = -16.013 (6) r10 / r11 = 0.793 (7) D45 / f = 0.122 In the imaging lens of Example 1, the first and fourth lenses are made of glass material, and the other lenses are made of plastic material.

[0042] Next, a description will be given of an imaging lens according to Example 2. Fig. 3 is a cross-sectional view taken along the optical axis showing the optical configuration of the imaging lens according to Example 2.

[0043] As shown in FIG. 3, this imaging lens is composed 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 positive meniscus third lens L3 with a concave surface facing the object side, an aperture stop S, a fourth lens L4 with a convex surface facing the object side and the image side and having positive refractive power, a fifth lens L5 with a concave surface facing the object side and the image side and having negative refractive power, and a sixth lens L6 with a convex surface facing the object side and the image side and having positive refractive power.

[0044] The overall specifications of the imaging lens of Example 2 are as follows: f: 0.83 mm f1: -5.879 mm f2: -5.010 mm f3: 11.009 mm f4: 2.236 mm f5: -1.888 mm f6: 1.882 mm FNO: 2.00 TTL: 13.158 mm Φimg: 3.945 mm

[0045] The surface data of the imaging lens of Example 2 is shown below.

[0046]

[0047] The aspherical data of the imaging lens of Example 2 is shown below. 3rd side K=0 A4=5.560E-02, A6=-1.526E-02, A8=1.705E-03, A10=-7.754E-05, A12=3.269E-07 4th side K=-1.207E+00 A4=4.946E-02, A6=6.310E-02, A8=-5.001E-02, A10=8.908E-03, A12=-1.119E-05 5th side K=-5.145E+01 A4=4.897E-04, A6=-2.320E-02, A8=9.267E-03, A10=-9.622E-04, A12=7.972E-06 6th side K=-3.966E-01 A4=8.211E-03, A6=-6.614E-03, A8=2.038E-02, A10=-1.005E-02, A12=4.402E-03 7th page K=0 A4=-2.864E-02, A6=6.344E-03 8th page K=0 A4=-4.796E-03, A6=5.530E-03 9th page K=0 A4=-1.292E-01, A6=9.999E-02, A8=-3.633E-02, A10=3.993E-03, A12=8.039E-05 10th page K=-2.148E+00 A4=-1.215E-01, A6=9.478E-02, A8=-3.538E-02, A10=5.196E-03, A12=3.123E-05 11th side K=-1.702E+00 A4=-5.755E-02, A6=1.850E-02, A8=-3.007E-03, A10=-1.252E-04, A12=-7.180E-06 12th side K=-1.299E+00 A4=1.326E-02, A6=7.784E-04, A8=-1.282E-03, A10=3.178E-04, A12=4.128E-06

[0048] The values ​​corresponding to conditional expressions (1) to (7) of the imaging lens of Example 2 are as follows: (1) f2 / f = -6.002 (2) r1 / r2 = 4.219 (3) r10 / D56 = 10.920 (4) D34 / f = 1.499 (5) f123 / f = -6.954 (6) r10 / r11 = 0.696 (7) D45 / f = 0.060 In the imaging lens of Example 2, the first and fourth lenses are made of glass material, and the other lenses are made of plastic material.

[0049] Next, a description will be given of an imaging lens according to Example 3. Fig. 5 is a cross-sectional view taken along the optical axis showing the optical configuration of the imaging lens according to Example 3.

[0050] As shown in FIG. 5, this imaging lens is composed of, in order from the object side, a negative meniscus first lens L1 with a convex surface facing the object side, a second lens L2 with a concave surface facing the object side and the image side and having negative refractive power, a positive meniscus third lens L3 with a concave surface facing the object side, an aperture stop S, a fourth lens L4 with a convex surface facing the object side and the image side and having positive refractive power, a fifth lens L5 with a concave surface facing the object side and the image side and having negative refractive power, and a sixth lens L6 with a convex surface facing the object side and the image side and having positive refractive power.

[0051] The overall specifications of the imaging lens of Example 3 are as follows: f: 0.95 mm f1: -6.796 mm f2: -2.965 mm f3: 7.570 mm f4: 2.209 mm f5: -1.899 mm f6: 2.178 mm FNO: 2.00 TTL: 13.190 mm Φimg: 3.945 mm

[0052] The surface data of the imaging lens of Example 3 is shown below.

[0053]

[0054] The aspherical data of the imaging lens of Example 3 is shown below. 3rd side K=0 A4=5.546E-02, A6=-1.515E-02, A8=1.738E-03, A10=-7.154E-05, A12=-2.401E-07 4th side K=-9.487E-01 A4=5.814E-02, A6=6.819E-02, A8=-5.257E-02, A10=8.748E-03, A12=4.267E-05 5th side K=-2.975E+01 A4=-1.989E-03, A6=-1.678E-02, A8=5.339E-03, A10=-9.056E-04, A12=9.774E-05 6th side K=-7.171E-01 A4=-8.048E-03, A6=-1.989E-03, A8=6.312E-03, A10=-5.051E-03, A12=1.479E-03 7th page K=0 A4=-1.917E-02, A6=-2.123E-02 8th page K=0 A4=-4.136E-02, A6=1.428E-02 9th page K=0 A4=-1.342E-01, A6=1.043E-01, A8=-2.522E-02, A10=-2.000E-05, A12=1.540E-03 10th page K=-2.164E+00 A4=-1.214E-01, A6=9.449E-02, A8=-3.351E-02, A10=5.048E-03, A12=-2.054E-04 Side 11 K=-1.888E+00 A4=-5.749E-02, A6=1.918E-02, A8=-2.820E-03, A10=-6.965E-05, A12=-2.330E-06 12th side K=-1.591E+00 A4=1.567E-02, A6=7.059E-04, A8=-1.472E-03, A10=1.961E-04, A12=7.482E-06

[0055] The values ​​corresponding to conditional expressions (1) to (7) of the imaging lens of Example 3 are as follows: (1) f2 / f = -3.107 (2) r1 / r2 = 3.400 (3) r10 / D56 = 10.898 (4) D34 / f = 1.195 (5) f123 / f = -5.405 (6) r10 / r11 = 1.200 (7) D45 / f = 0.122 In the imaging lens of Example 3, the first and fourth lenses are made of glass material, and the other lenses are made of plastic material.

[0056] Next, a description will be given of an imaging lens according to Example 4. Fig. 7 is a cross-sectional view taken along the optical axis showing the optical configuration of the imaging lens according to Example 4.

[0057] As shown in FIG. 7, this imaging lens is composed of, in order from the object side, a negative meniscus first lens L1 with a convex surface facing the object side, a second lens L2 with a concave surface facing the object side and the image side and having negative refractive power, a positive meniscus third lens L3 with a concave surface facing the object side, an aperture stop S, a fourth lens L4 with a convex surface facing the object side and the image side and having positive refractive power, a fifth lens L5 with a concave surface facing the object side and the image side and having negative refractive power, and a sixth lens L6 with a convex surface facing the object side and the image side and having positive refractive power.

[0058] The overall specifications of the imaging lens of Example 4 are as follows: f: 0.93 mm f1: -7.165 mm f2: -3.065 mm f3: 6.599 mm f4: 2.214 mm f5: -1.925 mm f6: 2.078 mm FNO: 2.00 TTL: 13.189 mm Φimg: 3.947 mm

[0059] The surface data of the imaging lens of Example 4 is shown below.

[0060]

[0061] The aspherical data of the imaging lens of Example 4 is shown below. 3rd side K=0 A4=5.572E-02, A6=-1.513E-02, A8=1.741E-03, A10=-7.369E-05 4th side K=-1.075E+00 A4=5.421E-02, A6=6.299E-02, A8=-5.059E-02, A10=8.582E-03 5th side K=-6.211E+01 A4=-1.213E-03, A6=-2.282E-02, A8=8.810E-03, A10=-1.399E-03 6th side K=-2.443E+00 A4=-3.495E-03, A6=-2.127E-02, A8=3.259E-02, A10=-1.839E-02 7th side K=0 A4=-1.324E-02, A6=-8.233E-03 8th side K=0 A4=-6.954E-03, A6=7.468E-03 9th side K=0 A4=-1.317E-01, A6=9.743E-02, A8=-3.490E-02, A10=6.224E-03 10th page K=-2.032E+00 A4=-1.201E-01, A6=9.557E-02, A8=-3.477E-02, A10=4.970E-03 11th page K=-1.694E+00 A4=-5.740E-02, A6=1.865E-02, A8=-2.770E-03, A10=-4.155E-05 12th page K=-1.224E+00 A4=1.262E-02, A6=9.221E-04, A8=-1.350E-03, A10=2.687E-04

[0062] The values ​​corresponding to conditional expressions (1) to (7) for the imaging lens of Example 4 are as follows: (1) f2 / f = -3.289 (2) r1 / r2 = 5.500 (3) r10 / D56 = 9.868 (4) D34 / f = 1.076 (5) f123 / f = -7.533 (6) r10 / r11 = 0.863 (7) D45 / f = 0.112 In the imaging lens of Example 4, the first and fourth lenses are made of glass material, and the other lenses are made of plastic material.

[0063] Next, a description will be given of an imaging lens according to Example 5. Fig. 9 is a cross-sectional view taken along the optical axis showing the optical configuration of the imaging lens according to Example 5.

[0064] As shown in FIG. 9 , this imaging lens is composed 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 positive meniscus third lens L3 with a concave surface facing the object side, an aperture stop S, a fourth lens L4 with a convex surface facing the object side and the image side and having positive refractive power, a fifth lens L5 with a concave surface facing the object side and the image side and having negative refractive power, and a sixth lens L6 with a convex surface facing the object side and the image side and having positive refractive power.

[0065] The overall specifications of the imaging lens of Example 5 are as follows: f: 0.86 mm f1: -5.887 mm f2: -5.091 mm f3: 8.417 mm f4: 2.234 mm f5: -1.897 mm f6: 1.872 mm FNO: 2.00 TTL: 12.928 mm Φimg: 3.945 mm

[0066] The surface data of the imaging lens of Example 5 is shown below.

[0067]

[0068] The aspherical data of the imaging lens of Example 5 is shown below. 3rd side K=0 A4= 5.547E-02, A6= -1.524E-02, A8= 1.706E-03, A10= -8.164E-05, A12= 4.907E-07 4th side K= -8.817E-01 A4= 4.953E-02, A6= 6.332E-02, A8= -4.990E-02, A10= 8.938E-03, A12= -7.961E-06 5th side K= -4.987E+01 A4= 1.588E-03, A6= -2.299E-02, A8= 9.206E-03, A10= -9.396E-04, A12= 2.994E-05 6th side K= -3.920E-01 A4= 8.210E-03, A6= 1.709E-04, A8= 8.004E-03, A10= 1.888E-03, A12= -2.243E-03 7th side K=0 A4= -2.737E-02, A6= 7.862E-03 8th side K=0 A4= -3.738E-03, A6= 4.652E-03 9th side K=0 A4= -1.282E-01, A6= 1.008E-01, A8= -3.728E-02, A10= 3.885E-03, A12= 6.661E-06 Page 10 K= -2.107E+00 A4= -1.216E-01, A6= 9.387E-02, A8= -3.546E-02, A10= 5.239E-03, A12= 6.701E-05 11th side K= -3.202E+00 A4= -5.751E-02, A6= 2.149E-02, A8= -2.680E-03, A10= -1.912E-04, A12= -6.872E-05 12th side K= -1.547E+00 A4= 6.560E-03, A6=-2.590E-03, A8= -7.430E-04, A10= 8.403E-04, A12= 1.473E-05

[0069] The values ​​corresponding to conditional expressions (1) to (7) for the imaging lens of Example 5 are as follows: (1) f2 / f = -5.892 (2) r1 / r2 = 4.242 (3) r10 / D56 = 22.278 (4) D34 / f = 1.554 (5) f123 / f = -10.440 (6) r10 / r11 = 0.745 (7) D45 / f = 0.058 In the imaging lens of Example 5, the first and fourth lenses are made of glass material, and the other lenses are made of plastic material.

[0070] Next, a description will be given of an imaging lens according to Example 6. Fig. 11 is a cross-sectional view taken along the optical axis showing the optical configuration of the imaging lens according to Example 6.

[0071] As shown in FIG. 11, this imaging lens is composed of, in order from the object side, a negative meniscus first lens L1 with a convex surface facing the object side, a second lens L2 with a concave surface facing the object side and the image side and having negative refractive power, a positive meniscus third lens L3 with a concave surface facing the object side, an aperture stop S, a fourth lens L4 with a convex surface facing the object side and the image side and having positive refractive power, a fifth lens L5 with a concave surface facing the object side and the image side and having negative refractive power, and a sixth lens L6 with a convex surface facing the object side and the image side and having positive refractive power.

[0072] The overall specifications of the imaging lens of Example 6 are as follows: f: 0.96 mm f1: -6.298 mm f2: -3.258 mm f3: 6.417 mm f4: 2.188 mm f5: -1.937 mm f6: 2.190 mm FNO: 2.00 TTL: 13.190 mm Φimg: 3.946 mm

[0073] The surface data of the imaging lens of Example 6 is shown below.

[0074]

[0075] The aspherical data of the imaging lens of Example 6 is shown below. 3rd side K=0 A4= 5.512E-02, A6= -1.515E-02, A8= 1.766E-03, A10= -6.584E-05, A12= -6.922E-07 4th side K= -1.320E+00 A4= 4.904E-02, A6= 6.362E-02, A8= -4.955E-02, A10= 8.702E-03, A12= -1.205E-04 5th side K= -6.130E-03 A4= -9.405E-03, A6= -2.503E-02, A8= 8.941E-03, A10= -1.823E-03 6th side K= -5.813E+00 A4= -4.978E-02, A6= -2.658E-02, A8= 8.710E-02, A10= -6.604E-02 7th side K=0 A4= -6.123E-02, A6= -1.327E-02 8th side K=0 A4= 1.073E-03, A6= 1.329E-03 9th side K=0 A4= -1.369E-01, A6= 9.472E-02, A8= -3.066E-02, A10= 4.778E-03, A12= -1.342E-04 10th side K= -2.264E+00 A4= -1.199E-01, A6= 9.667E-02, A8= -3.663E-02, A10= 4.625E-03, A12= 2.722E-04 11th side K= -1.264E+00 A4= -5.565E-02, A6= 1.778E-02, A8= -2.704E-03, A10= 1.373E-04, A12= -3.229E-05 12th side K= -9.853E-01 A4= 8.466E-03, A6= 1.481E-03, A8= -1.043E-03, A10= 2.509E-04, A12= -1.768E-05

[0076] The values ​​corresponding to conditional expressions (1) to (7) for the imaging lens of Example 5 are as follows: (1) f2 / f = -3.411 (2) r1 / r2 = 3.905 (3) r10 / D56 = 3.456 (4) D34 / f = 0.590 (5) f123 / f = -8.769 (6) r10 / r11 = 0.518 (7) D45 / f = 0.031 In the imaging lens of Example 6, the first and fourth lenses are made of glass material, and the other lenses are made of plastic material.

[0077] Next, a description will be given of an imaging lens according to Example 7. Fig. 13 is a cross-sectional view taken along the optical axis showing the optical configuration of the imaging lens according to Example 7.

[0078] As shown in FIG. 13, this imaging lens is composed 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 positive meniscus third lens L3 with a concave surface facing the object side, an aperture stop S, a fourth lens L4 with a convex surface facing the object side and the image side and having positive refractive power, a fifth lens L5 with a concave surface facing the object side and the image side and having negative refractive power, and a sixth lens L6 with a convex surface facing the object side and the image side and having positive refractive power.

[0079] The overall specifications of the imaging lens of Example 7 are as follows: f: 0.78 mm f1: -5.833 mm f2: -4.833 mm f3: 8.576 mm f4: 2.237 mm f5: -1.898 mm f6: 1.774 mm FNO: 2.00 TTL: 13.184 mm Φimg: 3.946 mm

[0080] The surface data of the imaging lens of Example 7 is shown below.

[0081]

[0082] The aspherical data of the imaging lens of Example 7 is shown below. 3rd side K=0 A4= 5.584E-02, A6= -1.526E-02, A8= 1.715E-03, A10= -8.159E-05, A12= 4.498E-07 4th side K= -9.099E-01 A4= 4.913E-02, A6= 6.326E-02, A8= -4.987E-02, A10= 8.891E-03, A12= -7.128E-06 5th side K= -5.224E+01 A4= 1.759E-03, A6= -2.294E-02, A8= 9.178E-03, A10= -9.650E-04, A12= -1.786E-05 6th side K= -5.823E-02 A4= 7.372E-03, A6= -2.099E-03, A8= 3.670E-03, A10= 2.623E-03, A12= -1.001E-03 7th side K=0 A4= -2.785E-02, A6= 6.582E-03 8th side K=0 A4= -1.472E-03, A6= 5.189E-03 9th side K=0 A4= -1.292E-01, A6= 1.002E-01, A8= -3.751E-02, A10= 4.165E-03, A12= 9.034E-04 Page 10 K= -2.098E+00 A4= -1.222E-01, A6= 9.386E-02, A8= -3.550E-02, A10= 5.233E-03, A12= 6.898E-05 11th side K= -3.173E+00 A4= -5.491E-02, A6= 2.269E-02, A8= -2.815E-03, A10= -2.415E-04, A12= 1.901E-05 12th side K= -1.735E+00 A4= 5.335E-03, A6= -4.158E-03, A8= -5.312E-04, A10= 1.150E-03, A12= 1.634E-04

[0083] The values ​​corresponding to conditional expressions (1) to (7) for the imaging lens of Example 7 are as follows: (1) f2 / f = -6.209 (2) r1 / r2 = 4.321 (3) r10 / D56 = 23.265 (4) D34 / f = 2.000 (5) f123 / f = -10.584 (6) r10 / r11 = 0.714 (7) D45 / f = 0.064 In the imaging lens of Example 7, the first and fourth lenses are made of glass material, and the other lenses are made of plastic material.

[0084] L1 First lens L2 Second lens L3 Third lens L4 Fourth lens L5 Fifth lens L6 Sixth lens FL Bandpass filter (dual pass filter) CG Cover glass I Imaging surface S Aperture diaphragm

Claims

1. An imaging lens comprising, in order from the object side, a first lens having negative refractive power, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having positive refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power, and satisfying the following conditional expressions: -6.3<f2 / f<-3 (1) 3.4<r1 / r2<5.6 (2) 3.0<r10 / D56<24 (3) 0.5<D34 / f<2.1 (4) Here, f is the focal length of the entire imaging lens system, f2 is the focal length of the second lens, 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, r10 is the radius of curvature of the image-side surface of the fifth lens, D56 is the air spacing on the optical axis between the fifth lens and the sixth lens, and D34 is the air spacing on the optical axis between the third lens and the fourth lens.

2. The imaging lens according to claim 1, wherein the following conditional expression is satisfied: −17<f123 / f<−5 (5) where f123 is the combined focal length of the first, second and third lenses.

3. The imaging lens according to claim 1 or 2, characterized in that the following conditional expression is satisfied: 0.5<r10 / r11<1.3 (6) where r11 is the radius of curvature of the object-side surface of the sixth lens.

4. The imaging lens according to claim 2, wherein the object-side surface of said third lens is a concave surface.

5. The imaging lens according to claim 3, wherein the following condition is satisfied: 0.01<D45 / f<0.2 (7) where D45 is the air distance on the optical axis between the fourth lens and the fifth lens.

Images