JP6818832B2 - Imaging lens system and imaging device - Google Patents

Description

The present invention relates to a wide-angle image pickup lens system and an image pickup apparatus.

In recent years, a lens compatible with a wide field of view has been required as an image pickup lens system for automobile mounting applications. As an image pickup lens system for automobile mounting applications, for example, there is an image pickup lens system used for an in-vehicle camera for confirming front, back, and sides for ensuring safety when driving a car.

The image pickup lens system of the in-vehicle camera is required to have an extremely wide field of view, a high resolution, and a bright image pickup lens system having an F value of about 2.0. In addition, compactness is also required for an imaging lens system for an in-vehicle camera.

Patent Document 1 describes, in order from the object side, a first lens having a negative power, a second lens having a negative power, a third lens having a positive power, an aperture, a fourth lens having a positive power, and a negative lens. An image pickup lens system composed of a fifth lens having the power of is described.

Japanese Unexamined Patent Publication No. 2014-89241

The image pickup lens system described in Patent Document 1 has a wide angle, is bright, and has high imaging performance. However, in the image pickup lens system used for an in-vehicle camera, it is desired to make the outer diameter of the lens arranged on the most object side smaller in order to make it as inconspicuous as possible when mounted on a vehicle. At the same time, as the number of pixels of the image sensor used increases, the image pickup lens system of the in-vehicle camera is required to have higher resolving power. In order to achieve high resolution, it is necessary to satisfactorily correct curvature of field in the region from the center to the periphery of the image sensor.

The present invention provides an imaging device including a wide-angle imaging lens and a wide-angle photographing lens that have a smaller outer diameter of the lens arranged on the object side, suppress the curvature of field, and have high resolution from the center to the peripheral portion. The purpose is to do.

The wide-angle imaging lens system of the present invention
From the object side,
With the negative first lens with the concave facing the image side,
A meniscus-shaped second lens with a concave on the object side,
A positive third lens with a biconvex shape near the optical axis,
Aperture and
The fourth lens, which is a negative lens,
The fifth lens, which is a positive lens,
It is composed of a sixth lens having an aspherical surface on at least one 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 on the object side. Further, by forming the second lens into a meniscus shape with a concave surface facing the object side, curvature of field can be corrected, so that good imaging performance can be obtained. As a result, it is possible to provide a wide-angle imaging lens system in which the outer diameter of the lens arranged closest to the object side is made smaller, the curvature of field is further suppressed, and the resolution is high from the center to the peripheral portion.

The wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (1) when 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 the conditional expression (1), while ensuring a long back focus, coma aberration and curvature of field are suppressed, and the overall length of the lens system is not lengthened. If the upper limit of the conditional expression (1) is exceeded, the positive power of the third lens becomes larger than the negative power of the first lens, so that the image plane collapses and it becomes difficult to lengthen the back focus. If it falls below the lower limit of the conditional expression (1), the negative power of the first lens becomes larger than the positive power of the third lens, so that it becomes easy to secure the back focus, but the total length of the image pickup lens system becomes longer. As the length increases, it becomes difficult to correct the aberration generated by the increase in the power of the first lens.

Further, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (2).
0.9 << | f1 / f3 | <1.1 ... (2)

The wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (3) when 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)

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

Further, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (4).
0.05 <f / f2 <0.15 ... (4)

The wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (5) 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)

The conditional expression (5) is a conditional expression for correcting chromatic aberration. If it is less than the lower limit of the conditional expression (5), the negative power of the fourth lens becomes smaller than the positive power of the fifth lens, so that the chromatic aberration correction is insufficient and the imaging performance deteriorates. If the upper limit of the conditional expression (5) is exceeded, the negative power of the fourth lens becomes larger than the positive power of the fifth lens, so that the chromatic aberration correction becomes excessive and the imaging performance deteriorates. Therefore, according to this configuration, by satisfying the conditional expression (5), appropriate chromatic aberration correction can be performed and deterioration of imaging performance can be prevented.

Further, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (6).
-1.6 <f4 / f5 <-1.2 ... (6)

The wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (7) when 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) defines the total length of the image pickup lens system. If it falls below the lower limit of the conditional expression (7), the negative power of the first lens becomes larger than the power of the entire lens system, which causes an increase in the overall length of the imaging lens system. If the upper limit of the conditional expression (7) is exceeded, the negative power of the first lens becomes smaller than the power of the entire lens system, so that it is difficult to secure a predetermined back focus. Therefore, according to this configuration, by satisfying the conditional expression (7), it is possible to secure a predetermined back focus while preventing an increase in the overall length of the image pickup lens system.

Further, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (8).
1.9 << | f1 / f | <2.0 ... (8)

The wide-angle imaging lens system of the present invention satisfies the following conditional expression (9) 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. preferable.
-1.2 <R2 / R3 <-0.4 ... (9)

Conditional expression (9) defines coma, curvature of field, and distortion. If it falls below the lower limit of the conditional expression (9), the image plane collapses, and it becomes difficult to correct the curvature of field. If the upper limit of the conditional expression (9) is exceeded, the distortion aberration will increase, and it will be difficult to control the angle of view. Therefore, according to this configuration, by satisfying the conditional expression (9), it is possible to correct the curvature of field and prevent the increase in distortion.

Further, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (10).
-1.0 <R2 / R3 <-0.6 ... (10)

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

By satisfying the condition equation (11), the wide-angle image pickup lens system of the present invention can secure the back focus while keeping the total length of the image pickup lens system short, and can perform good chromatic aberration correction. If it exceeds the upper limit of the conditional expression (11), it is advantageous to secure the back focus, but it becomes difficult to correct the chromatic aberration and the total length of the image pickup lens system becomes long. If it is less than the lower limit of the conditional expression (11), the chromatic aberration correction becomes excessive and it becomes difficult to secure the back focus. Further, by satisfying the conditional expressions (11) and (12) at the same time, good chromatic aberration correction becomes possible.

The wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (13) when the focal length of the entire system is f and the combined focal length of the second lens and the third lens is f23.
1.3 <f23 / f <1.65 ... (13)

By satisfying the conditional expression (13), the wide-angle imaging lens system of the present invention can secure a long back focus and can correct chromatic aberration well. If it is less than the lower limit of the conditional expression (13), it is effective in reducing axial chromatic aberration and lateral chromatic aberration, but it becomes difficult to secure the back focus. If the upper limit of the conditional expression (13) is exceeded, the back focus tends to be lengthened, but it becomes difficult to satisfactorily correct the chromatic aberration.

Further, the wide-angle imaging lens system of the present invention preferably satisfies the following conditional expression (14).
1.4 <f23 / f <1.55 ... (14)

The imaging device of the present invention
With the above-mentioned imaging lens system
It has an image pickup device arranged at a focal position of the image pickup lens system.

According to the present invention, an imaging device including a wide-angle imaging lens and a wide-angle photographing lens which have a smaller outer diameter of the lens arranged on the object side, suppress the curvature of field, and have high resolution from the center to the peripheral portion. Can be provided.

It is sectional drawing of the image pickup lens system which concerns on Example 1. FIG. It is an aberration diagram of the image pickup lens system which concerns on Example 1. FIG. It is sectional drawing of the image pickup lens system which concerns on Example 2. FIG. It is an aberration diagram of the image pickup lens system which concerns on Example 2. FIG. It is sectional drawing of the image pickup lens system which concerns on Example 3. FIG. It is an aberration diagram of the image pickup lens system which concerns on Example 3. FIG. It is sectional drawing of the image pickup apparatus which concerns on embodiment.

Hereinafter, examples of the wide-angle imaging lens system 11 according to the embodiment of the present invention will be described.

[Example 1]
FIG. 1 is a diagram showing the configuration of the wide-angle imaging lens system 11 of the first embodiment. As shown in FIG. 1, in the wide-angle imaging lens system 11 of the first embodiment, the first lens L1 having a concave shape on the image side and having a negative power and the concave surface facing the object side are directed in order from the object side. A second lens L2 having a meniscus shape, a third lens L3 having a biconvex shape near the optical axis Z and having a positive power, an aperture STOP, a fourth lens L4 having a negative power, and a positive power. It is composed of a fifth lens L5 having the above lens L5 and a sixth lens L6 having at least one lens surface having an aspherical surface. The image plane of the wide-angle image lens system 11 is indicated by IMG. In the wide-angle imaging lens system 11 of the first embodiment, 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 having a negative power. The object-side lens surface S1 of the first lens L1 is a flat surface, and the image-side lens surface S2 is a spherical surface having a positive curvature. The image-side lens surface S2 has a concave curved surface portion recessed toward the object side.

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

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

The first lens L1 has a function of converting an incident light ray from a large incident angle into a small angle along the optical axis Z. The image-side lens surface S2 of the first lens L1 has a negative power in order to spread the light beam. Since the second lens L2 has a meniscus shape with a concave surface facing the object side, curvature of field can be satisfactorily corrected. The third lens L3 is a positive lens having a convex shape toward the object side, and has a function of converging the light rays emitted by the first lens L1.

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

The fifth lens L5 is an aspherical lens having a positive power. The object-side lens surface S10 of the fifth lens L5 is an aspherical surface having a positive curvature, and the image-side lens surface S11 is an aspherical surface having a negative curvature. The object-side lens surface S10 has a convex curved surface portion that protrudes toward the object side. The image side lens surface S11 has a convex curved surface portion protruding 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 aspherical lens having a negative power. The object-side lens surface S12 of the sixth lens L6 is an aspherical surface having a negative curvature, and the image-side lens surface S13 is an aspherical surface having a negative curvature. The object-side lens surface S12 has a concave curved surface portion recessed on the image side. The image side lens surface S13 has a convex curved surface portion protruding toward the image side.

The fourth lens L4 is a lens having a negative power and a large dispersion. The fifth lens L5 is a lens having a positive power and a small dispersion. Therefore, by combining the fourth lens L4 and the fifth lens L5, axial chromatic aberration and Magnification chromatic aberration can be corrected.

The cover glass 12 is a glass plate for protecting the image sensor. The cover glass 12 is treated integrally with the wide-angle image pickup lens system 11 at the time of designing the wide-angle image pickup lens system 11. However, the cover glass 12 is not an essential component of the wide-angle image pickup lens system 11.

Table 1 shows the lens data of each lens surface of the wide-angle imaging lens system 11. As the lens data, the radius of curvature of each surface, the surface spacing, the refractive index, and the Abbe number are listed. The surface marked with "*" indicates that it is an aspherical surface.

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

Table 2 shows the aspherical coefficient for defining the aspherical shape of the lens surface which is the aspherical surface in the wide-angle imaging lens system 11 of the first embodiment. In Table 2, for example, "-1.673481E-03" means "-1.673481 × 10-3".

2 (a) to 2 (c) are a longitudinal aberration diagram, an image plane curvature diagram, and a distortion aberration diagram of the wide-angle image pickup lens system 11 of the first embodiment. As shown in FIGS. 2A to 2C, in the wide-angle image pickup 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. 2A, the horizontal axis indicates the position where the light ray intersects the optical axis Z, and the vertical axis indicates the height at the pupil diameter. In the curvature of field diagram of FIG. 2B, the horizontal axis represents the distance in the optical axis Z direction, and the vertical axis represents the image height (angle of view). In FIG. 2B, Sag shows curvature of field on the sagittal plane and Tan shows curvature of field on the tangential plane. In the distortion diagram of FIG. 2C, the horizontal axis represents the amount of distortion (%) of the image, and the vertical axis represents the image height (angle of view). FIG. 2A shows the simulation results with light rays having wavelengths of 656 nm, 546 nm and 436 nm, and FIGS. 2B and 2C show the simulation results using light rays having wavelengths 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 value is FNo, the distance from the object-side lens surface S1 of the first lens L1 to the imaging surface IMG of the wide-angle imaging lens system 11 is the "optical total length", and the focal distance of the entire lens system is f. , The focal distance of the first lens L1 is f1, the focal distance of the second lens L2 is f2, the focal distance of the third lens L3 is f3, the focal distance of the fourth lens L4 is f4, and the focal distance of the fifth lens L5 is f5. , These characteristic values when the focal distance of the sixth lens L6 is f6 are as shown in Table 3. The various focal lengths were calculated using light rays with a wavelength of 546 nm.

[Example 2]
FIG. 3 is a diagram showing the configuration of the wide-angle imaging lens system 11 of the second embodiment. As shown in FIG. 3, the first lens L1 to the sixth lens L6 have the same shape as that of the first embodiment. In the wide-angle imaging lens system 11 of the second embodiment, 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 of each lens surface of the wide-angle imaging lens system 11 of Example 2.

Table 5 shows the aspherical coefficient for defining the aspherical shape of the lens surface which is the aspherical surface in the wide-angle imaging lens system 11 of the second embodiment.

4 (a) to 4 (c) are a longitudinal aberration diagram, an image plane curvature diagram, and a distortion aberration diagram of the wide-angle image pickup lens system 11 of the second embodiment. As shown in FIGS. 4A to 4C, in the wide-angle image pickup lens system 11 of Example 2, the half angle of view ω is 68.2 ° and the F value is 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]
FIG. 5 is a diagram showing the configuration of the wide-angle imaging lens system 11 of the third embodiment. The first lens L1 to the fifth lens L5 have the same shape as that of the first embodiment. The shape of the sixth lens L6 is different from that of the first embodiment.

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

In the wide-angle imaging lens system 11 of the third embodiment, 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 of each lens surface of the wide-angle imaging lens system 11 of Example 3.

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

6 (a) to 6 (c) are a longitudinal aberration diagram, an image plane curvature diagram, and a distortion aberration diagram of the wide-angle image pickup lens system 11 of the third embodiment. As shown in FIGS. 6A to 6C, in the wide-angle image pickup lens system 11 of Example 3, the half angle of view ω is 67.1 ° and the F value is 2.0.

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

[Summary of conditional expressions]
Table 10 shows the results of calculating various parameters used in the conditional expressions (1) to (14) in the wide-angle imaging lens system 11 of Examples 1 to 3. The combined focal distance between the second lens L2 and the third lens L3 is f23, the combined focal distance between the fourth lens L4 and the fifth lens L5 is f45, the radius of curvature of the image side lens surface of the first lens L1 is R2, and the second lens. Various parameters are calculated, where the radius of curvature of the object-side lens surface of the two lenses L2 is R3, the number of abs of the first lens L1 is νd1, the number of abs of the second lens L2 is νd2, and the number of abs of the third lens L3 is νd3. doing.

As described above, in the wide-angle imaging lens system of the present embodiment, in order from the object side, a negative first lens having a concave shape toward the image side, a meniscus-shaped second lens having a concave shape facing the object side, and light. A positive third lens having a biconvex shape near the axis, an aperture, a fourth lens which is a negative lens, a fifth lens which is a positive lens, and a sixth lens having an aspherical surface on at least one surface. In the wide-angle imaging lens system composed of the above, the effective diameter of the first lens can be reduced by making the second lens concave on the object side. Further, the curvature of field can be corrected by forming the second lens into a meniscus shape with the concave surface facing the object side. As a result, it is possible to provide a wide-angle imaging lens system in which the outer diameter of the lens arranged closest to the object side is made smaller, the curvature of field is further suppressed, and the resolution is high from the center to the peripheral portion.

The wide-angle imaging lens system of the present embodiment has a long back focus by satisfying the following conditional expression (1) when the focal length of the first lens is f1 and the focal length of the third lens is f3. While ensuring the above, coma and curvature of field are suppressed, and the total length of the lens system is not lengthened.
0.8 << | f1 / f3 | <1.2 ... (1)

Further, the wide-angle imaging lens system of the present embodiment preferably 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, the distortion is increased by satisfying the following conditional expression (3). It can be prevented and image plane correction can be performed.
0 <f / f2 <0.2 (3)

Further, the wide-angle imaging lens system of the present embodiment preferably 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, appropriate chromatic aberration is satisfied by satisfying the following conditional expression (5). Correction can be performed to prevent deterioration of imaging performance.
-1.8 <f4 / f5 <-1.0 ... (5)

Further, the wide-angle imaging lens system of the present embodiment preferably 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, the total length of the imaging lens system is satisfied by satisfying the following conditional expression (7). It is possible to secure a predetermined back focus while preventing the increase of the lens.
1.8 << | f1 / f | <2.1 ... (7)

Further, the wide-angle imaging lens system of the present embodiment preferably satisfies the following conditional expression (8).
1.9 << | f1 / f | <2.0 ... (8)

The wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (9) 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. As a result, coma aberration and curvature of field can be corrected, and an increase in distortion can be prevented.
-1.2 <R2 / R3 <-0.4 ... (9)

Further, the wide-angle imaging lens system of the present embodiment preferably satisfies the following conditional expression (10).
-1.0 <R2 / R3 <-0.6 ... (10)

In the wide-angle imaging lens system of the present embodiment, the focal length of the first lens is f1, the combined focal length of the second lens and the third lens is f23, the first lens, the second lens, and the third lens. When the number of lenses is νd1, νd2, and νd3, respectively, by satisfying the following conditional equations (11) and (12), it is possible to secure the back focal length while keeping the total length of the imaging lens system short, and it is good. Color aberration correction becomes possible.
-1.1 <f1 / f23 <-0.9 ... (11)
35 <(νd1 + νd2 + νd3) / 3 <60 ... (12)

The wide-angle imaging lens system of the present embodiment satisfies the following conditional expression (13) when the focal length of the entire system is f and the combined focal length of the second lens and the third lens is f23. , A long back focus can be secured, and good chromatic aberration correction becomes possible.
1.3 <f23 / f <1.65 ... (13)

Further, the wide-angle imaging lens system of the present embodiment preferably satisfies the following conditional expression (14).
1.4 <f23 / f <1.55 ... (14)

[Example of application to imaging device]
FIG. 7 is a diagram showing a configuration of an image pickup apparatus 10 using the wide-angle image pickup lens system 11. The image pickup device 10 includes a wide-angle image pickup lens system 11, a cover glass 12, and an image pickup element 13. The wide-angle image pickup lens system 11, the cover glass 12, and the image pickup element 13 are housed in a housing (not shown).

The image pickup device 13 is an element that converts the received light into an electric signal, and for example, a CCD image sensor or a CMOS image sensor is used. The image pickup device 13 is arranged at the focal position of the wide-angle image pickup lens system 11. The horizontal angle of view is an angle of view corresponding to the horizontal direction of the image sensor 13.

The cover glass 12 is provided on the image pickup element 13 in order to protect the image pickup element 13 from foreign matter.

The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the spirit. For example, the application of the wide-angle imaging lens system 11 of the present invention is not limited to an in-vehicle camera, and can be used for other applications such as a surveillance camera and a camera mounted on a small electronic device such as a mobile phone. ..

10 Image sensor 11 Wide-angle image lens system 12 Cover glass 13 Image sensor L1 to L6 1st to 6th lenses

Claims (8)

From the object side, a negative first lens with a concave shape on the image side, a meniscus-shaped second lens with a concave shape on the object side, and a positive third lens with a biconvex shape near the optical axis. The aperture, the fourth lens which is a negative lens whose image side lens surface has a positive curvature, and the fifth lens which is a positive lens whose object side lens surface has a positive curvature and the image side lens surface has a negative curvature. A wide-angle imaging lens system composed of a lens and a sixth lens whose lens surface on the object side has a negative curvature. The wide-angle imaging lens system according to claim 1, wherein the object-side lens surface of the fourth lens has a negative curvature. The wide-angle imaging lens system according to claim 1, wherein the object-side lens surface of the fourth lens is an aspherical surface. The wide-angle imaging lens system according to claim 1, wherein at least one surface of the fifth lens is an aspherical surface. The wide-angle imaging lens system according to claim 1, wherein the sixth lens is a negative lens. The wide-angle imaging lens system according to claim 1, wherein the image-side lens surface of the sixth lens has a negative curvature. The wide-angle imaging lens system according to claim 1, wherein at least one surface of the sixth lens is an aspherical surface. An image pickup apparatus comprising the image pickup lens system according to claim 1 and an image pickup device arranged at a focal position of the image pickup lens system.

Images