JP7531659B2 - Imaging lens system and imaging device - Google Patents

Description

The present invention relates to a wide-angle imaging lens system and an imaging device.

In recent years, there has been a demand for lenses with a wide field of view as imaging lens systems for use in automobiles. For example, imaging lens systems for use in automobiles include imaging lens systems used in on-board cameras for checking the front, back, and sides of a vehicle to ensure safety when driving.

The imaging lens system for an in-vehicle camera is required to have an extremely wide field of view, high resolution, and a bright image with an F-number of about 2.0. In addition, imaging lens systems for in-vehicle cameras are also required to be compact.

Patent document 1 describes an imaging lens system that is composed of, in order from the object side, a first lens having negative power, a second lens having negative power, a third lens having positive power, an aperture, a fourth lens having positive power, and a fifth lens having negative power.

JP 2014-89241 A

The imaging lens system described in Patent Document 1 is wide-angle, bright, and has high imaging performance. However, in imaging lens systems used in vehicle-mounted cameras, it is desirable to reduce the outer diameter of the lens located closest to the object in order to make the imaging lens system as inconspicuous as possible when mounted on a vehicle. At the same time, as the number of pixels in the imaging elements used increases, higher resolution is required for the imaging lens system of the vehicle-mounted camera. To achieve high resolution, it is necessary to effectively correct the field curvature in the area from the center to the periphery of the imaging element.

The present invention aims to provide a wide-angle imaging lens and an imaging device equipped with a wide-angle imaging lens that has a smaller outer diameter of the lens located closest to the object, suppresses curvature of field, and provides high resolution from the center to the periphery.

The wide-angle imaging lens system of the present invention comprises:
From the object side,
a negative first lens having a concave surface facing an image side;
a second lens having a meniscus shape with a concave surface facing the object side;
a positive third lens having a biconvex shape near the optical axis;
Aperture and
a fourth lens which is a negative lens; and
A fifth lens which is a positive lens;
and a sixth lens having at least one aspheric surface.

In the wide-angle imaging lens system of the present invention, the effective diameter of the first lens can be reduced by making the second lens concave toward the object side. Furthermore, by making the second lens a meniscus shape with its concave surface facing the object side, the field curvature can be corrected, resulting in good imaging performance. This makes it possible to provide a wide-angle imaging lens system that has a smaller outer diameter of the lens positioned closest to the object, suppresses field curvature, and provides high resolution from the center to the periphery.

It is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (1), where the focal length of the first lens is f1 and the focal length of the third lens is f3.
0.8<|f1/f3|<1.2...(1)

According to this configuration, by satisfying conditional expression (1), coma aberration and curvature of field are suppressed while ensuring a long back focus, and the overall length of the lens system is not increased. If the upper limit of conditional expression (1) is exceeded, the positive power of the third lens becomes larger relative to the negative power of the first lens, causing the image surface to tilt and making it difficult to increase the back focus. If the lower limit of conditional expression (1) is exceeded, the negative power of the first lens becomes larger relative to the positive power of the third lens, making it easier to ensure the back focus, but the overall length of the imaging lens system becomes longer and it becomes difficult to correct the aberrations caused by the increased power of the first lens.

It is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (2).
0.9<|f1/f3|<1.1...(2)

It is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (3), where the focal length of the entire system is f and the focal length of the second lens is f2.
0<f/f2<0.2 (3)

Conditional expression (3) is a conditional expression for performing image plane correction. If the lower limit of conditional expression (3) is exceeded with the concave surface facing the object side, the negative power of the second lens becomes large, causing increased distortion and making it difficult to control the angle of view. If the upper limit of conditional expression (3) is exceeded, the positive power of the second lens becomes large, causing increased image plane tilt and deteriorating imaging performance. Therefore, with this configuration, by satisfying conditional expression (3), it is possible to prevent an increase in distortion and perform image plane correction.

It is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (4).
0.05<f/f2<0.15...(4)

In the wide-angle imaging lens system of the present invention, it is preferable that the following conditional expression (5) be satisfied, when the focal length of the fourth lens is f4 and the focal length of the fifth lens is f5.
-1.8<f4/f5<-1.0...(5)

Conditional formula (5) is a conditional formula for correcting chromatic aberration. If the lower limit of conditional formula (5) is exceeded, the negative power of the fourth lens will be smaller than the positive power of the fifth lens, resulting in insufficient chromatic aberration correction and degradation of imaging performance. If the upper limit of conditional formula (5) is exceeded, the negative power of the fourth lens will be larger than the positive power of the fifth lens, resulting in excessive chromatic aberration correction and degradation of imaging performance. Therefore, with this configuration, by satisfying conditional formula (5), appropriate chromatic aberration correction can be performed and degradation of imaging performance can be prevented.

It is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (6).
-1.6<f4/f5<-1.2...(6)

It is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (7), where the focal length of the entire system is f and the focal length of the first lens is f1.
1.8<|f1/f|<2.1...(7)

Conditional expression (7) specifies the overall length of the imaging lens system. If the lower limit of conditional expression (7) is exceeded, the negative power of the first lens becomes large relative to the power of the entire lens system, resulting in an increase in the overall length of the imaging lens system. If the upper limit of conditional expression (7) is exceeded, the negative power of the first lens becomes small relative to the power of the entire lens system, making it difficult to ensure a specified back focus. Therefore, with this configuration, by satisfying conditional expression (7), it is possible to ensure a specified back focus while preventing an increase in the overall length of the imaging lens system.

Moreover, it is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (8).
1.9<|f1/f|<2.0...(8)

It is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (9), where R2 is the radius of curvature of the image-side surface of the first lens and R3 is the radius of curvature of the object-side surface of the second lens.
-1.2<R2/R3<-0.4...(9)

Conditional expression (9) defines coma, field curvature, and distortion. If the lower limit of conditional expression (9) is not met, the image plane will tilt, making it difficult to correct the field curvature. If the upper limit of conditional expression (9) is exceeded, distortion will increase, making it difficult to control the angle of view. Therefore, with this configuration, by satisfying conditional expression (9), it is possible to correct field curvature and prevent an increase in distortion.

It is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (10).
-1.0<R2/R3<-0.6 (10)

In the wide-angle imaging lens system of the present invention, it is preferable that the following conditional expressions (11) and (12) are satisfied when the focal length of the first lens is f1, the composite focal length of the second lens and the third lens is f23, and the Abbe numbers of the first lens, the second lens, and the third lens are νd1, νd2, and νd3, respectively.
-1.1<f1/f23<-0.9 (11)
35<(νd1+νd2+νd3)/3<60...(12)

By satisfying conditional expression (11), the wide-angle imaging lens system of the present invention can ensure the back focus while keeping the overall length of the imaging lens system short, and can achieve good chromatic aberration correction. Exceeding the upper limit of conditional expression (11) is advantageous for ensuring the back focus, but it becomes difficult to correct chromatic aberration and the overall length of the imaging lens system becomes long. Falling below the lower limit of conditional expression (11) results in excessive chromatic aberration correction and makes it difficult to ensure the back focus. Furthermore, by simultaneously satisfying conditional expressions (11) and (12), good chromatic aberration correction is possible.

It is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (13), where the focal length of the entire system is f and the composite focal length of the second lens and the third lens is f23.
1.3<f23/f<1.65...(13)

By satisfying conditional expression (13), the wide-angle imaging lens system of the present invention can ensure a long back focus and can perform good chromatic aberration correction. If the lower limit of conditional expression (13) is exceeded, it is effective in reducing axial chromatic aberration and lateral chromatic aberration, but it becomes difficult to ensure the back focus. If the upper limit of conditional expression (13) is exceeded, it becomes easier to lengthen the back focus, but it becomes difficult to perform good chromatic aberration correction.

It is preferable that the wide-angle imaging lens system of the present invention satisfies the following conditional expression (14).
1.4<f23/f<1.55...(14)

The imaging device of the present invention comprises:
The imaging lens system described above;
and an imaging element disposed at a focal position of the imaging lens system.

The present invention can provide a wide-angle imaging lens that has a smaller outer diameter of the lens located closest to the object, suppresses curvature of field, and provides high resolution from the center to the periphery, and an imaging device equipped with the wide-angle imaging lens.

1 is a cross-sectional view of an imaging lens system according to a first embodiment. 4A to 4C are aberration diagrams of the imaging lens system according to Example 1. FIG. 11 is a cross-sectional view of an imaging lens system according to a second embodiment. 10A to 10C are aberration diagrams of an imaging lens system according to Example 2. FIG. 11 is a cross-sectional view of an imaging lens system according to a third embodiment. 11A to 11C are aberration diagrams of an imaging lens system according to Example 3. 1 is a cross-sectional view of an imaging device according to an embodiment.

Below, we will explain an example of a wide-angle imaging lens system 11 according to an embodiment of the present invention.

[Example 1]
Fig. 1 is a diagram showing the configuration of a wide-angle imaging lens system 11 of Example 1. As shown in Fig. 1, the wide-angle imaging lens system 11 of Example 1 is composed of, in order from the object side, a first lens L1 having a concave shape toward the image side and negative power, a second lens L2 having a meniscus shape with a concave surface facing the object side, a third lens L3 having a biconvex shape near the optical axis Z and positive power, an aperture stop STOP, a fourth lens L4 having negative power, a fifth lens L5 having positive power, and a sixth lens L6 having at least one lens surface aspheric. The image forming surface of the wide-angle imaging lens system 11 is indicated by IMG. In the wide-angle imaging lens system 11 of Example 1, the second lens L2, the fourth lens L4, the fifth lens L5, and the sixth lens L6 are plastic lenses, and the first lens L1 and the third lens L3 are glass lenses.

The first lens L1 is a spherical meniscus lens with negative power. The object-side lens surface S1 of the first lens L1 is flat, and the image-side lens surface S2 is a spherical surface with positive curvature. The image-side lens surface S2 has a concave curved portion that is recessed toward the object side.

The second lens L2 is an aspheric lens with positive power. The object-side lens surface S3 of the second lens L2 is an aspheric surface with negative curvature, and the image-side lens surface S4 is an aspheric surface with negative curvature. The object-side lens surface S3 has a concave curved portion recessed toward the image side. The image-side lens surface S4 has a convex curved portion protruding toward the image side.

The third lens L3 is a spherical lens with positive power. The object-side lens surface S5 is a spherical surface with positive curvature, and the image-side lens surface S6 is a spherical surface with negative curvature. The object-side lens surface S5 has a convex curved portion that protrudes toward the object side, and the image-side lens surface S6 has a convex curved portion that protrudes toward the image side.

The first lens L1 has the function of converting incident light rays from a large angle of incidence to a small angle along the optical axis Z. The image-side lens surface S2 of the first lens L1 has negative power in order to expand the light rays. The second lens L2 has a meniscus shape with its concave surface facing the object side, so that it can effectively correct field curvature. The third lens L3 is a positive lens with a convex shape facing the object side, and has the function of converging the light rays diverged by the first lens L1.

The fourth lens L4 is an aspheric lens with negative power. The object-side lens surface S8 of the fourth lens L4 is an aspheric surface with negative curvature, and the image-side lens surface S9 is an aspheric surface with positive curvature. The object-side lens surface S8 has a concave curved surface recessed toward the image side. The image-side lens surface S9 has a concave curved surface recessed toward the object side.

The fifth lens L5 is an aspheric lens with positive power. The object-side lens surface S10 of the fifth lens L5 is an aspheric surface with positive curvature, and the image-side lens surface S11 is an aspheric surface with negative curvature. The object-side lens surface S10 has a convex curved portion that protrudes toward the object side. The image-side lens surface S11 has a convex curved portion that protrudes toward the image side. The object-side lens surface S10 of the fifth lens L5 is bonded to the image-side lens surface S9 of the fourth lens L4 with an adhesive.

The sixth lens L6 is an aspheric lens with negative power. The object-side lens surface S12 of the sixth lens L6 is an aspheric surface with negative curvature, and the image-side lens surface S13 is an aspheric surface with negative curvature. The object-side lens surface S12 has a concave curved portion recessed toward the image side. The image-side lens surface S13 has a convex curved portion protruding toward the image side.

The fourth lens L4 is a lens with negative power and large dispersion. The fifth lens L5 is a lens with positive power and small dispersion. Therefore, by combining the fourth lens L4 and the fifth lens L5, it is possible to correct axial chromatic aberration and chromatic aberration of magnification.

The cover glass 12 is a glass plate for protecting the imaging element. When designing the wide-angle imaging lens system 11, the cover glass 12 is treated as an integral part of the wide-angle imaging lens system 11. However, the cover glass 12 is not an essential component of the wide-angle imaging lens system 11.

Table 1 shows the lens data of each lens surface of the wide-angle imaging lens system 11. The lens data includes the radius of curvature, surface spacing, refractive index, and Abbe number of each surface. Surfaces marked with an "*" are aspheric surfaces.

The aspheric shape used for the lens surface is expressed by the following formula, where z is the amount of sag, c is the inverse of the radius of curvature, k is the cone coefficient, r is the ray height from the optical axis, and the aspheric coefficients of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th orders are A4, A6, A8, A10, A12, A14, and A16, respectively.

Table 2 shows the aspheric coefficients for defining the aspheric shape of the lens surface that is made aspheric in the wide-angle imaging lens system 11 of Example 1. In Table 2, for example, "-1.673481E-03" means "-1.673481×10-3".

2(a) to (c) are longitudinal aberration diagrams, field curvature diagrams, and distortion aberration diagrams of the wide-angle imaging lens system 11 of Example 1. As shown in FIGS. 2(a) to (c), in the wide-angle imaging lens system 11 of Example 1, the half angle of view ω is 67.5° and the F value is 2.0. In the longitudinal aberration diagram of FIG. 2(a), the horizontal axis indicates the position where the light ray intersects with the optical axis Z, and the vertical axis indicates the height at the pupil diameter. In the field curvature diagram of FIG. 2(b), the horizontal axis indicates the distance in the optical axis Z direction, and the vertical axis indicates the image height (field angle). In FIG. 2(b), Sag indicates the field curvature in the sagittal plane, and Tan indicates the field curvature in the tangential plane. In the distortion aberration diagram of FIG. 2(c), the horizontal axis indicates the amount of image distortion (%), and the vertical axis indicates the image height (field angle). Figure 2(a) shows the simulation results using light rays with wavelengths of 656 nm, 546 nm, and 436 nm, while Figures 2(b) and (c) show the simulation results using light rays with a wavelength of 546 nm.

Table 3 shows the results of calculating the characteristic values of the wide-angle imaging lens system 11 of Example 1. In the wide-angle imaging lens system 11, the F-number is FNo, the distance from the object-side lens surface S1 of the first lens L1 to the image plane IMG of the wide-angle imaging lens system 11 is the "total optical length", the focal length of the entire lens system is f, the focal length of the first lens L1 is f1, the focal length of the second lens L2 is f2, the focal length of the third lens L3 is f3, the focal length of the fourth lens L4 is f4, the focal length of the fifth lens L5 is f5, and the focal length of the sixth lens L6 is f6. The characteristic values are as shown in Table 3. The various focal lengths were calculated using light with a wavelength of 546 nm.

[Example 2]
Fig. 3 is a diagram showing the configuration of a wide-angle imaging lens system 11 of Example 2. As shown in Fig. 3, the first lens L1 to the sixth lens L6 have the same shapes as those of Example 1. In the wide-angle imaging lens system 11 of Example 2, the second lens L2, the fourth lens L4, the fifth lens L5, and the sixth lens L6 are plastic lenses, and the first lens L1 and the third lens L3 are glass lenses.

Table 4 shows the lens data for each lens surface of the wide-angle imaging lens system 11 of Example 2.

Table 5 shows the aspheric coefficients for defining the aspheric shape of the aspheric lens surface in the wide-angle imaging lens system 11 of Example 2.

Figures 4(a) to (c) are diagrams showing longitudinal aberration, curvature of field, and distortion of the wide-angle imaging lens system 11 of Example 2. As shown in Figures 4(a) to (c), the wide-angle imaging lens system 11 of Example 2 has a half angle of view ω of 68.2° and an F-number of 2.0.

Table 6 shows the results of calculating the characteristic values of the wide-angle imaging lens system 11 of Example 2.

[Example 3]
5 is a diagram showing the configuration of a wide-angle imaging lens system 11 of Example 3. The first lens L1 to the fifth lens L5 have the same shapes as those in Example 1. The shape of the sixth lens L6 is different from that in Example 1.

The sixth lens L6 is an aspheric lens with negative power. The object-side lens surface S12 of the sixth lens L6 is an aspheric surface with negative curvature, and the image-side lens surface S13 is an aspheric surface with positive curvature. The object-side lens surface S12 has a concave curved portion recessed toward the image side near the optical axis Z. The image-side lens surface S13 has a concave curved portion recessed toward the object side near the optical axis Z.

In the wide-angle imaging lens system 11 of Example 3, the second lens L2, the fourth lens L4, the fifth lens L5, and the sixth lens L6 are plastic lenses, and the first lens L1 and the third lens L3 are glass lenses.

Table 7 shows the lens data for each lens surface of the wide-angle imaging lens system 11 of Example 3.

Table 8 shows the aspheric coefficients for defining the aspheric shape of the aspheric lens surface in the wide-angle imaging lens system 11 of Example 3.

Figures 6(a) to 6(c) are diagrams showing longitudinal aberration, curvature of field, and distortion of the wide-angle imaging lens system 11 of Example 3. As shown in Figures 6(a) to 6(c), the wide-angle imaging lens system 11 of Example 3 has a half angle of view ω of 67.1° and an F-number of 2.0.

Table 9 shows the results of calculating the characteristic values of the wide-angle imaging lens system 11 of Example 3.

[Conditional Expression Summary]
Table 10 shows the results of calculating various parameters used in conditional expressions (1) to (14) in the wide-angle imaging lens systems 11 of Examples 1 to 3. The various parameters are calculated with the composite focal length of the second lens L2 and the third lens L3 as f23, the composite focal length of the fourth lens L4 and the fifth lens L5 as f45, the radius of curvature of the image-side lens surface of the first lens L1 as R2, the radius of curvature of the object-side lens surface of the second lens L2 as R3, the Abbe number of the first lens L1 as νd1, the Abbe number of the second lens L2 as νd2, and the Abbe number of the third lens L3 as νd3.

In this way, the wide-angle imaging lens system of the present embodiment is composed of, in order from the object side, a negative first lens with a concave surface facing the image side, a meniscus-shaped second lens with a concave surface facing the object side, a positive third lens with a biconvex shape near the optical axis, an aperture, a negative fourth lens, a positive fifth lens, and a sixth lens with at least one aspheric surface. By making the second lens concave toward the object side, the effective diameter of the first lens can be reduced. Furthermore, by making the second lens meniscus-shaped with a concave surface facing the object side, the curvature of field can be corrected. This makes it possible to provide a wide-angle imaging lens system that has a smaller outer diameter of the lens arranged closest to the object side, suppresses the curvature of field, and has high resolution from the center to the periphery.

In the wide-angle imaging lens system of the present embodiment, when the focal length of the first lens is f1 and the focal length of the third lens is f3, the following conditional expression (1) is satisfied, thereby ensuring a long back focus, suppressing coma aberration and curvature of field, and preventing the overall length of the lens system from becoming long.
0.8<|f1/f3|<1.2...(1)

Moreover, it is preferable that the wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (2).
0.9<|f1/f3|<1.1...(2)

In the wide-angle imaging lens system of the present embodiment, when the focal length of the entire system is f and the focal length of the second lens is f2, by satisfying the following conditional expression (3), it is possible to prevent an increase in distortion and perform image plane correction.
0<f/f2<0.2 (3)

Moreover, it is preferable that the wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (4).
0.05<f/f2<0.15...(4)

In the wide-angle imaging lens system of the present embodiment, when the focal length of the fourth lens is f4 and the focal length of the fifth lens is f5, by satisfying the following conditional expression (5), it is possible to perform appropriate correction of chromatic aberration and prevent deterioration of imaging performance.
-1.8<f4/f5<-1.0...(5)

Moreover, it is preferable that the wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (6).
-1.6<f4/f5<-1.2...(6)

In the wide-angle imaging lens system of the present embodiment, when the focal length of the entire system is f and the focal length of the first lens is f1, by satisfying the following conditional expression (7), it is possible to ensure a predetermined back focus while preventing an increase in the overall length of the imaging lens system.
1.8<|f1/f|<2.1...(7)

Moreover, it is preferable that the wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (8).
1.9<|f1/f|<2.0...(8)

In the wide-angle imaging lens system of the present embodiment, when the radius of curvature of the image-side surface of the first lens is R2 and the radius of curvature of the object-side surface of the second lens is R3, by satisfying the following conditional expression (9), it is possible to correct coma and field curvature and prevent an increase in distortion:
-1.2<R2/R3<-0.4...(9)

Moreover, it is preferable that the wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (10).
-1.0<R2/R3<-0.6 (10)

In the wide-angle imaging lens system of the present embodiment, when the focal length of the first lens is f1, the composite focal length of the second lens and the third lens is f23, and the Abbe numbers of the first lens, the second lens, and the third lens are νd1, νd2, and νd3, respectively, by satisfying the following conditional expressions (11) and (12), it is possible to ensure the back focus while keeping the overall length of the imaging lens system short, and also to achieve good chromatic aberration correction.
-1.1<f1/f23<-0.9 (11)
35<(νd1+νd2+νd3)/3<60...(12)

In the wide-angle imaging lens system of the present embodiment, when the focal length of the entire system is f and the composite focal length of the second lens and the third lens is f23, by satisfying the following conditional expression (13), it is possible to ensure a long back focus and achieve good chromatic aberration correction.
1.3<f23/f<1.65...(13)

Moreover, it is preferable that the wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (14).
1.4<f23/f<1.55...(14)

[Application example to imaging device]
7 is a diagram showing the configuration of an imaging device 10 using a wide-angle imaging lens system 11. The imaging device 10 has the wide-angle imaging lens system 11, a cover glass 12, and an imaging element 13. The wide-angle imaging lens system 11, the cover glass 12, and the imaging element 13 are housed in a housing (not shown).

The image sensor 13 is an element that converts received light into an electrical signal, and may be, for example, a CCD image sensor or a CMOS image sensor. The image sensor 13 is disposed at the focal position of the wide-angle imaging lens system 11. The horizontal angle of view is the angle of view corresponding to the horizontal direction of the image sensor 13.

The cover glass 12 is placed on the imaging element 13 to protect the imaging element 13 from foreign matter.

The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the invention. For example, the use of the wide-angle imaging lens system 11 of the present invention is not limited to vehicle-mounted cameras, but can also be used for other purposes, such as surveillance cameras and cameras mounted on small electronic devices such as mobile phones.

10 imaging device 11 wide-angle imaging lens system 12 cover glass 13 imaging elements L1 to L6 first lens to sixth lens

Claims (7)

From the object side,
a negative first lens having a concave surface facing an image side;
a second lens having a meniscus shape with a concave surface facing the object side;
a positive third lens having a biconvex shape near the optical axis;
Aperture and
a fourth lens immediately behind the diaphragm, which is a negative lens having a concave surface facing the object side and a concave surface facing the image side;
a fifth lens which is a positive lens having a convex surface facing the object side and a convex surface facing the image side;
A sixth lens element having a concave surface facing the object side;
A wide-angle imaging lens system comprising:
At least one surface of the sixth lens is aspheric . The wide-angle imaging lens system according to claim 1, characterized in that the object-side lens surface of the fourth lens has a negative curvature. The wide-angle imaging lens system according to claim 1, characterized in that the object-side lens surface of the fourth lens is aspheric. The wide-angle imaging lens system according to claim 1, characterized in that at least one surface of the fifth lens is aspheric. The wide-angle imaging lens system according to claim 1, characterized in that the sixth lens is a negative lens. The wide-angle imaging lens system according to claim 1, characterized in that the image-side lens surface of the sixth lens has a negative curvature. An imaging device having the imaging lens system according to claim 1 and an imaging element disposed at the focal position of the imaging lens system.

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