JP2023075468A - Wide-angle lens - Google Patents

Abstract

To provide a wide-angle lens which can be used with a large image sensor.SOLUTION: A wide-angle lens is provided, comprising a front group 110, an aperture stop 80, and a rear group 120 in order from the object side to the image side. The front group 110 consists of a first lens 10, a second lens 20, and a third lens 30 in order from the most object side to the image side. The rear group 120 consists of a fourth lens 40, a fifth lens 50, and a sixth lens 60 in order from the most object side to the image side. The wide-angle lens satisfies the following conditional expression: 2.000≤R51/f0≤10.000, where f0 represents a focal length of the entire lens system and R51 represents a curvature radius of an object-side surface of the fifth lens.SELECTED DRAWING: Figure 1

Description

The present invention relates to wide-angle lenses used in various imaging systems.

In a wide-angle lens, a lens configuration of 5 groups and 6 lenses has been proposed in order to obtain high resolution (see Patent Document 1). In the wide-angle lens disclosed in Patent Document 1, a front group, a diaphragm, and a rear group are arranged in order from the object side to the image side. In the front group, three lenses are arranged from the most object side toward the image side. In the rear group, one lens and one cemented lens are arranged from the most object side to the image side.

JP 2016-57562 A

The wide-angle lens described in Patent Document 1 is used in sensor devices such as automobiles. In this wide-angle lens, a 1/4-inch imaging device is arranged on the reduction-side imaging plane. Here, performance improvement of the sensor device is required. In this case, for the purpose of improving the performance of the sensor device, the use of a large image sensor, for example, a ⅓ inch image sensor is under study. However, the wide-angle lens described in Patent Document 1 and the like is designed to be suitable for a 1/4-inch image pickup device. There is a problem that the total length becomes large and the necessary optical performance cannot be obtained.

In view of the above problems, an object of the present invention is to provide a wide-angle lens that can be applied to a large image sensor.

In order to solve the above problems, a wide-angle lens according to the present invention comprises a front group, a diaphragm, and a rear group in order from the object side to the image side, the front group being the most from the object side to the image side. The rear group consists of a first lens, a second lens and a third lens in order, and the rear group consists of a fourth lens, a fifth lens and a sixth lens in order from the most object side to the image side, and the first lens group The lens has negative power and has a concave shape on the image side lens surface, the second lens has negative power and has a concave shape on the image side lens surface, and the third lens has , having a positive power, the fourth lens having a positive power, the fifth lens having a negative power, an object-side lens surface having a convex shape, and an image-side lens surface the sixth lens has a positive power, the object-side lens surface and the image-side lens surface have convex shapes; A cemented lens in which a lens surface on the image side of the lens and a lens surface on the object side of the sixth lens are cemented together, the focal length of the entire lens system is f0, and the curvature of the lens surface on the object side of the fifth lens is If the radius is R51, the following conditional expression: 2.000≤R51/f0≤10.000
is characterized by satisfying

In the present invention, since the conditional expression is satisfied, even when a wide-angle lens is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system and to suppress the occurrence of various aberrations. be able to. If the value of the conditional expression exceeds the lower limit, the curvature radius R51 of the lens surface 51 becomes too small. That is, the power of the object-side lens surface of the fifth lens becomes too strong. Therefore, it becomes difficult to suppress the occurrence of various aberrations. If the value of the conditional expression exceeds the upper limit, the radius of curvature R51 of the object-side lens surface of the fifth lens becomes too large. That is, the power of the object-side lens surface of the fifth lens becomes too weak. Therefore, the total length of the entire lens system tends to increase.

In the present invention, assuming that the radius of curvature of the object-side lens surface of the fifth lens is R51 and the radius of curvature of the image-side lens surface of the fifth lens is R52, the following conditional expression: 1.000≦(R51+R52) / (R51-R52) ≤ 3.000
is preferably satisfied. In the present invention, since the conditional expression is satisfied, even when a wide-angle lens is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system and to suppress the occurrence of various aberrations. be able to. If the value of the conditional expression exceeds the lower limit, the power of the fifth lens becomes too strong, making it difficult to suppress the occurrence of various aberrations. If the value of the conditional expression exceeds the upper limit, the power of the fifth lens becomes too weak, and the total length of the entire lens system tends to increase.

In the present invention, assuming that the focal length of the entire lens system is f0 and the combined focal length of the fifth lens and the sixth lens is f56, the following conditional expression: 2.500≦f56/f0≦6.000
is preferably satisfied. In the present invention, since the conditional expression is satisfied, even when a wide-angle lens is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system and to suppress the occurrence of various aberrations. be able to. If the value of the conditional expression exceeds the lower limit, the combined power of the fifth lens and the sixth lens becomes too strong, making it difficult to suppress the occurrence of various aberrations. If the value of the conditional expression exceeds the upper limit, the combined power of the fifth lens and the sixth lens becomes too weak, and the total length of the entire lens system tends to increase.

In the present invention, assuming that the focal length of the entire lens system is f0, and the combined focal length of the fourth lens, the fifth lens, and the sixth lens is f456, the following conditional expression: 2.200≦f456/f0≦2 .800
is preferably satisfied. In the present invention, since the conditional expression is satisfied, even when a wide-angle lens is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system and to suppress the occurrence of various aberrations. be able to. If the value of the conditional expression exceeds the lower limit, the composite power of the rear group consisting of the fourth, fifth and sixth lenses becomes too strong, making it difficult to suppress the occurrence of various aberrations. If the value of the conditional expression exceeds the upper limit, the composite power of the rear group becomes too weak, and the total length of the entire lens system tends to increase.

In the present invention, assuming that the focal length of the entire lens system is f0 and the combined focal length of the first lens, the second lens and the third lens is f123, the following conditional expression −6.000≦f123/f0≦ -1.300
is preferably satisfied. In the present invention, since the conditional expression is satisfied, even when a wide-angle lens is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system and to suppress the occurrence of various aberrations. be able to. If the value of the conditional expression exceeds the lower limit, the composite power of the front group consisting of the first lens, the second lens and the third lens becomes too strong, making it difficult to suppress the occurrence of various aberrations. If the value of the conditional expression exceeds the upper limit, the composite power of the front group becomes too weak, and the total length of the entire lens system tends to increase.

In the present invention, assuming that the combined focal length of the first lens, the second lens and the third lens is f123, and the combined focal length of the fourth lens, the fifth lens and the sixth lens is f456, the following conditional expression -3.000 ≤ f123/f456 ≤ -0.500
is preferably satisfied. In the present invention, since the conditional expression is satisfied, even when a wide-angle lens is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system and to suppress the occurrence of various aberrations. be able to. When the value of the conditional expression exceeds the lower limit, the composite power of the front group consisting of the first, second and third lenses is the composite power of the rear group consisting of the fourth, fifth and sixth lenses. Since it becomes too weak for power, the total length of the entire lens system tends to increase. If the value of the conditional expression exceeds the upper limit, the combined power of the front group becomes too strong relative to the combined power of the rear group, making it difficult to suppress the occurrence of various aberrations.

In the present invention, assuming that the focal length of the entire lens system is f0 and the total length of the entire lens system is d0, the following conditional expression: 11.000≤d0/f0≤15.000
is preferably satisfied. In the present invention, since the conditional expression is satisfied, even when a wide-angle lens is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system and to suppress the occurrence of various aberrations. be able to. When the value of the conditional expression exceeds the lower limit, it is difficult to suppress the occurrence of various aberrations. If the value of the conditional expression exceeds the upper limit, each lens system tends to be large, and the total length of the entire lens system tends to be large.

In the present invention, when the focal length of the entire lens system is f0 and the focal length of the second lens is f2, the following conditional expression −2.450≦f2/f0≦−2.000
is preferably satisfied. In the present invention, since the conditional expression is satisfied, it is possible to suppress the total length of the entire lens system from increasing and to suppress the occurrence of various aberrations. If the value of the conditional expression exceeds the lower limit, the power of the second lens becomes weak, so that the occurrence of various aberrations can be suppressed, but the total length of the entire lens system tends to increase. If the value of the conditional expression exceeds the upper limit, it is possible to suppress the total length of the entire lens system from increasing, but the power of the second lens becomes too strong, making it difficult to suppress the occurrence of various aberrations. .

In the present invention, when the focal length of the entire lens system is f0 and the combined focal length of the first lens and the second lens is f12, the following conditional expression −1.300≦f12/f0≦−1.100
is preferably satisfied. In the present invention, since the conditional expression is satisfied, it is possible to suppress the total length of the entire lens system from increasing and to suppress the occurrence of various aberrations. If the value of the conditional expression exceeds the lower limit, the combined power of the first lens and the second lens becomes weak, so that the occurrence of various aberrations can be suppressed, but the distance between the first lens and the second lens becomes wider. Therefore, the total length of the entire lens system tends to be large. If the value of the conditional expression exceeds the upper limit, it is possible to suppress an increase in the total length of the entire lens system, but the combined power of the first lens and the second lens becomes too strong, thereby suppressing the occurrence of various aberrations. becomes difficult.

According to the present invention, even when a wide-angle lens is used for an imaging device larger than 1/4 inch, it is possible to prevent the total length of the entire lens system from increasing, and to prevent the occurrence of various aberrations.

1 is an explanatory diagram of a wide-angle lens according to Embodiment 1 of the present invention; FIG. 2 is a diagram showing data of the wide-angle lens shown in FIG. 1; FIG. 2 is an explanatory diagram showing spherical aberration of the wide-angle lens shown in FIG. 1; FIG. 2 is an explanatory diagram showing lateral chromatic aberration of the wide-angle lens shown in FIG. 1; FIG. FIG. 2 is an explanatory diagram showing astigmatism and distortion of the wide-angle lens shown in FIG. 1; FIG. 2 is an explanatory diagram showing lateral aberration of the wide-angle lens shown in FIG. 1; FIG. 6 is an explanatory diagram of a wide-angle lens according to Embodiment 2 of the present invention; 8 is a diagram showing data of the wide-angle lens shown in FIG. 7; FIG. 8 is an explanatory diagram showing spherical aberration of the wide-angle lens shown in FIG. 7; FIG. FIG. 8 is an explanatory diagram showing lateral chromatic aberration of the wide-angle lens shown in FIG. 7; 8 is an explanatory diagram showing astigmatism and distortion of the wide-angle lens shown in FIG. 7; FIG. FIG. 8 is an explanatory diagram showing lateral aberration of the wide-angle lens shown in FIG. 7; FIG. 10 is an explanatory diagram of a wide-angle lens according to Embodiment 3 of the present invention; 14 is a diagram showing data of the wide-angle lens shown in FIG. 13; FIG. FIG. 14 is an explanatory diagram showing spherical aberration of the wide-angle lens shown in FIG. 13; FIG. 14 is an explanatory diagram showing lateral chromatic aberration of the wide-angle lens shown in FIG. 13; FIG. 14 is an explanatory diagram showing astigmatism and distortion of the wide-angle lens shown in FIG. 13; FIG. 14 is an explanatory diagram showing lateral aberration of the wide-angle lens shown in FIG. 13;

A wide-angle lens 100 to which the present invention is applied will be described below. The wide-angle lens 100 is used in sensor devices such as automobiles.

(Embodiment 1)
FIG. 1 is an explanatory diagram of a wide-angle lens 100 according to Embodiment 1 of the present invention. As shown in FIG. 1, the wide-angle lens 100 of this embodiment includes a front group 110, a diaphragm 80, a rear group 120, and an infrared cut filter 81 in order from the object side La to the image side Lb.

The front group 110 is composed of a first lens 10, a second lens 20, and a third lens 30 in order from the object side La to the image side Lb. The rear group 120 consists of a fourth lens 40, a fifth lens 50, and a sixth lens 60 in order from the object side La to the image side Lb. On the image side Lb of the sixth lens, a flat infrared cut filter 81, a translucent cover 82, and an imaging device 85 are arranged in order from the object side La to the image side Lb.

The first lens 10 has negative power. The first lens 10 has a convex lens surface 11 on the object side La and a concave lens surface 12 on the image side Lb. The second lens 20 has negative power. The second lens 20 has a convex lens surface 21 on the object side La and a concave lens surface 22 on the image side Lb. The second lens 20 has aspherical shapes on both sides. The third lens 30 has positive power. The third lens 30 has a convex lens surface 31 on the object side La and a concave lens surface 32 on the image side Lb. The third lens 30 has aspherical shapes on both sides.

The fourth lens 40 has positive power. The fourth lens 40 has a convex lens surface 41 on the object side La and a convex lens surface 42 on the image side Lb. The fifth lens 50 has negative power. The fifth lens 50 has a convex lens surface 51 on the object side La and a concave lens surface 52 on the image side Lb. The fifth lens 50 has aspherical shapes on both surfaces. The sixth lens 60 has positive power. The sixth lens 60 has a convex lens surface 61 on the object side La and a convex lens surface 62 on the image side Lb. The sixth lens 60 has aspherical shapes on both sides. The fifth lens 50 and the sixth lens 60 are cemented lenses in which a lens surface 52 on the image side Lb of the fifth lens 50 and a lens surface 61 on the object side La of the sixth lens 60 are cemented with an adhesive (not shown). is 70. With such a configuration, the rear group 120 includes the cemented lens 70
, chromatic aberration can be appropriately corrected.

(lens configuration)
FIG. 2 is a diagram showing wide-angle lens 100 data according to the first embodiment. As shown in FIG. 2, FIG. 2 shows the following characteristics as characteristics of the wide-angle lens 100. FIG. Note that the values shown in FIG. 2 are rounded off.

The following items are shown in FIG. Here, the total length of the entire lens system is the distance on the optical axis L from the lens surface 11 on the object side La of the first lens 10 to the imaging surface 850 of the imaging device 85 . The total length between the first lens and the sixth lens is the distance on the optical axis L from the lens surface 11 of the first lens 10 on the object side La to the lens surface 62 of the sixth lens on the image side Lb.

Focal length f0 (Effective Focal Length) of the entire lens system
Overall length d0 (Total Track) of the entire lens system
F value (Image Space) of the entire lens system
Max. Field Angle
Pupil Diameter
Total length between 1st lens and 6th lens (L1R1-L6R2 Track)

In addition, FIG. 2 shows the following items for each surface. A surface numbered with * is an aspherical surface. The unit of radius of curvature, thickness, focal length, and lens radius is mm.

Here, the lens surface 11 constitutes the first surface. The lens surface 12 constitutes the second surface. The lens surface 21 constitutes the third surface. The lens surface 22 constitutes the fourth surface. The lens surface 31 constitutes the fifth surface. The lens surface 32 constitutes the sixth surface. A diaphragm 80 constitutes the seventh surface. The lens surface 41 constitutes the eighth surface. The lens surface 42 constitutes the ninth surface. The lens surface 51 constitutes the tenth surface. The lens surface 52 and the lens surface 61 constitute the 11th surface. The lens surface 62 constitutes the 12th surface. The surface 811 on the object side La of the infrared cut filter 81 constitutes the 13th surface, and the surface 812 on the image side Lb constitutes the 14th surface. The surface 821 on the object side La of the cover 82 constitutes the fifteenth surface, and the surface 822 on the image side Lb constitutes the sixteenth surface. An imaging surface 850 of the imaging device 85 constitutes the seventeenth surface.

When the lens surface is a convex surface protruding toward the object side or a concave surface recessed toward the object side, the radius of curvature is assumed to be a positive value, and the lens surface is a convex surface protruding toward the image side or the image side. If the surface is concave toward , the radius of curvature is given as a negative value. The amount of sag (Sag) is defined as a point on the optical axis L of the virtual reference plane at the outermost circumference of the effective diameter of the lens surface, when a virtual plane perpendicular to the optical axis is a virtual reference plane. is the distance to the top point. Further, when the sag amount is a positive value, the point on the optical axis L on the virtual reference plane is positioned closer to the object side than the point on the optical axis L of the lens surface, and when the sag amount is a negative value, the virtual A point on the optical axis L on the reference plane is located closer to the image side than a point on the optical axis L on the lens surface.

Radius of curvature
Thickness
Refractive index (Nd)
Abbe number (νd)
focal length (f)
Lens radius (Semi-D)
Sag amount (Sag)

FIG. 2 also shows the aspherical surface coefficient when the shape of the aspherical surface is represented by the following formula (Equation 1). In the following formula, z is the sag amount (axis in the optical axis direction), r is the height in the direction perpendicular to the optical axis (ray height), k is the conic coefficient, and c is the reciprocal of the radius of curvature.

In the wide-angle lens 100 of Embodiment 1, the focal length of the entire lens system is f0, and the curvature radius of the lens surface 51 on the object side La of the fifth lens 50 is R51, the following conditional expression (1)
2.000≦R51/f0≦10.000 (1)
meet.

In this form,
f0 = 0.939mm
R51=4.711mm
is. Therefore, R51/f0=5.071, which satisfies conditional expression (1).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (1), even when the wide-angle lens 100 is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system. At the same time, the occurrence of various aberrations can be suppressed. When the light reflected by the image pickup surface 850 of the image sensor 85 is incident on the lens surface 51, it is difficult to reflect again on the lens surface 51, so the generation of ghost can be suppressed. If the value of conditional expression (1) exceeds the lower limit, the radius of curvature R51 of the lens surface 51 becomes too small. That is, the power of the lens surface 51 becomes too strong. Therefore, it becomes difficult to suppress the occurrence of various aberrations. Also, when the light reflected by the imaging surface 850 of the imaging element 85 is incident on the lens surface 51 , the light is reflected again on the lens surface 51 and easily returns to the imaging element 85 . As a result, ghosts are likely to occur. If the value of conditional expression (1) exceeds the upper limit, the radius of curvature R51 of the lens surface 51 becomes too large. That is, the power of the lens surface 51 becomes too weak. Therefore, the total length of the entire lens system tends to increase.

In the wide-angle lens 100 of Embodiment 1, the radius of curvature of the lens surface 51 on the object side La of the fifth lens 50 is R51, and the radius of curvature of the lens surface 52 on the image side Lb of the fifth lens 50 is R52. Conditional expression (2)
1.000≦(R51+R52)/(R51−R52)≦3.000 (2)
meet.
In this condition, more preferably 1.000≦(R51+R52)/(R51−R52)≦2.000 Conditional expression (2a)
meet.

In this form,
R51=4.711mm
R52=1.000mm
is. Therefore, (R51+R52)/(R51-R52)=1.539, which satisfies conditional expression (2).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (2), even when the wide-angle lens 100 is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system. At the same time, the occurrence of various aberrations can be suppressed. If the value of conditional expression (2) exceeds the lower limit, the power of the fifth lens 50 becomes too strong, making it difficult to suppress the occurrence of various aberrations. If the value of conditional expression (2) exceeds the upper limit, the power of the fifth lens 50 becomes too weak, and the total length of the entire lens system tends to increase.

Assuming that the focal length of the entire lens system of the wide-angle lens 100 of Embodiment 1 is f0 and the combined focal length of the fifth lens 50 and the sixth lens 60 is f56, the following conditional expression (3)
2.500≦f56/f0≦6.000 (3)
meet.

In this form,
f0 = 0.939mm
f56=3.325mm
is. Therefore, f56/f0=3.541, which satisfies conditional expression (3).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (3), even when the wide-angle lens 100 is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system. At the same time, the occurrence of various aberrations can be suppressed. If the value of conditional expression (3) exceeds the lower limit, the composite power of the fifth lens 50 and the sixth lens 60 becomes too strong, making it difficult to suppress the occurrence of various aberrations. If the value of conditional expression (3) exceeds the upper limit, the synthetic power of the fifth lens 50 and the sixth lens 60 becomes too weak, and the total length of the entire lens system tends to increase.

Assuming that the focal length of the entire lens system of the wide-angle lens 100 of Embodiment 1 is f0, and the combined focal length of the fourth lens 40, the fifth lens 50, and the sixth lens 60 is f456, the following conditional expression (4)
2.200≦f456/f0≦2.800 (4)
meet.

In this form,
f0 = 0.939mm
f456=2.381mm
is. Therefore, f456/f0=2.535, which satisfies conditional expression (4).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (4), even when the wide-angle lens 100 is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system. At the same time, the occurrence of various aberrations can be suppressed. If the value of conditional expression (4) exceeds the lower limit, the combined power of the rear group 120 consisting of the fourth lens 40, the fifth lens 50 and the sixth lens 60 becomes too strong, thereby suppressing the occurrence of various aberrations. it becomes difficult to If the value of conditional expression (4) exceeds the upper limit, the composite power of the rear group 120 becomes too weak, and the total length of the entire lens system tends to increase.

Assuming that the focal length of the entire lens system of the wide-angle lens 100 of Embodiment 1 is f0, and the combined focal length of the first lens 10, the second lens 20 and the third lens 30 is f123, the following conditional expression (5)
-6.000≤f123/f0≤-1.300 (5)
meet.

In this form,
f0 = 0.939mm
f123=-2.034mm
is. Therefore, f123/f0=-2.166, which satisfies conditional expression (5).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (5), even when the wide-angle lens 100 is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system. At the same time, the occurrence of various aberrations can be suppressed. If the value of conditional expression (5) exceeds the lower limit, the combined power of the front group 110 consisting of the first lens 10, the second lens 20 and the third lens 30 becomes too strong, thereby suppressing the occurrence of various aberrations. it becomes difficult to If the value of conditional expression (5) exceeds the upper limit, the combined power of front group 110 becomes too weak, and the total length of the entire lens system tends to increase.

In the wide-angle lens 100 of Embodiment 1, the combined focal length of the first lens 10, the second lens 20 and the third lens 30 is f123, and the combined focal length of the fourth lens 40, the fifth lens 50 and the sixth lens 60 is f123. If f456, the following conditional expression (6)
-5.000≤f123/f456≤-0.300 (6)
meet.

In this form,
f123=-2.034mm
f456 = 2.381mm
is. Therefore, f123/f456=-0.854, which satisfies conditional expression (6).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (6), even when the wide-angle lens 100 is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system. At the same time, the occurrence of various aberrations can be suppressed. When the value of conditional expression (6) exceeds the lower limit, the combined power of the front group 110 consisting of the first lens 10, the second lens 20 and the third lens 30 is the fourth lens 40, the fifth lens 50 and Since the combined power of the rear group 120 composed of the sixth lens 60 is too weak, the total length of the entire lens system tends to increase. If the value of conditional expression (6) exceeds the upper limit, the combined power of the front group 110 becomes too strong relative to the combined power of the rear group 120, making it difficult to suppress the occurrence of various aberrations. Become.

In the wide-angle lens 100 of Embodiment 1, the focal length of the entire lens system is f0, and the total length of the entire lens system is d0, the following conditional expression (7)
11.000≤d0/f0≤15.000 (7)
meet.

In this form,
f0 = 0.939mm
d0 = 13.506 mm
is. Therefore, d0/f0=14.383, which satisfies conditional expression (7).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (7), even when the wide-angle lens 100 is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system. At the same time, the occurrence of various aberrations can be suppressed. When the value of conditional expression (7) exceeds the lower limit, it is difficult to suppress the occurrence of various aberrations. If the value of conditional expression (7) exceeds the upper limit, each lens system tends to be large, and the total length of the entire lens system tends to be large.

Assuming that the focal length of the entire lens system of the wide-angle lens 100 of Embodiment 1 is f0 and the focal length of the second lens 20 is f2, the following conditional expression (8)
-2.450≤f2/f0≤-2.000 (8)
meet.

In this form,
f0 = 0.939mm
f2=-2.305mm
is. Therefore, f2/f0=-2.545, which satisfies conditional expression (8).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (8), it is possible to suppress an increase in the total length of the entire lens system and to suppress the occurrence of various aberrations. When the value of conditional expression (8) exceeds the lower limit, the power of the second lens 20 is weakened, so that the occurrence of various aberrations can be suppressed, but the total length of the entire lens system tends to increase. If the value of conditional expression (8) exceeds the upper limit, it is possible to suppress the total length of the entire lens system from increasing, but since the power of the second lens 20 becomes too strong, the occurrence of various aberrations should be suppressed. becomes difficult.

In the wide-angle lens 100 of Embodiment 1, if the focal length of the entire lens system is f0 and the combined focal length of the first lens 10 and the second lens 20 is f12, the following conditional expression (9)
-1.300≤f12/f0≤-1.100 (9)
meet.

In this form,
f0 = 0.939mm
f12=-1.170mm
is. Therefore, f12/f0=-1.246, which satisfies conditional expression (9).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (9), it is possible to suppress an increase in the total length of the entire lens system and to suppress the occurrence of various aberrations. When the value of conditional expression (9) exceeds the lower limit, the combined power of the first lens 10 and the second lens 20 becomes weak, so that the occurrence of various aberrations can be suppressed. 20 tends to increase, the overall length of the entire lens system tends to increase. If the value of conditional expression (9) exceeds the upper limit, it is possible to suppress an increase in the total length of the entire lens system, but the combined power of the first lens 10 and the second lens 20 becomes too strong, resulting in various aberrations. It becomes difficult to suppress the occurrence of

In the wide-angle lens 100 of Embodiment 1, the focal length of the entire lens system is f0, and the radius of curvature of the lens surface 31 on the object side La of the third lens 30 is R31, the following conditional expression (10)
1.500≦R31/f0≦8.000 (10)
meet.
In this condition, more preferably 1.500≦R31/f0≦7.200 (10a)
meet.

In this form,
f0 = 0.939mm
R31=2.457mm
is. Therefore, R31/f0=2.617, which satisfies conditional expression (10).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (10), even when the wide-angle lens 100 is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system. At the same time, the occurrence of various aberrations can be suppressed. If the value of conditional expression (10) exceeds the lower limit, the radius of curvature R31 of the lens surface 31 becomes too small. That is, the power of the lens surface 31 becomes too strong. Therefore, it becomes difficult to suppress the occurrence of various aberrations. If the value of conditional expression (10) exceeds the upper limit, the radius of curvature R31 of the lens surface 31 becomes too large. That is, the power of the lens surface 31 becomes too weak. Therefore, the total length of the entire lens system tends to increase.

In the wide-angle lens 100 of Embodiment 1, the radius of curvature of the lens surface 31 on the object side La of the third lens 30 is R31, and the radius of curvature of the lens surface 32 on the image side Lb of the third lens 30 is R32. Conditional expression (11)
-3.000≤(R31+R32)/(R31-R32)≤-1.400 (11)
meet.

In this form,
R31=2.457mm
R32=6.386mm
is. Therefore, (R31+R32)/(R31-R32)=-2.251, which satisfies conditional expression (11).

Since the wide-angle lens 100 of Embodiment 1 satisfies the conditional expression (11), even when the wide-angle lens 100 is used for an imaging device larger than 1/4 inch, it is possible to suppress an increase in the total length of the entire lens system. At the same time, the occurrence of various aberrations can be suppressed. If the value of conditional expression (11) exceeds the lower limit, the power of the third lens 30 becomes too strong, making it difficult to suppress the occurrence of various aberrations. If the value of conditional expression (11) exceeds the upper limit, the power of the third lens 30 becomes too weak, and the total length of the entire lens system tends to increase.

(Aberration characteristics of wide-angle lens 100)
FIG. 3 is an explanatory diagram showing spherical aberration of the wide-angle lens 100 shown in FIG. FIG. 4 is an explanatory diagram showing the chromatic aberration of magnification of the wide-angle lens 100 shown in FIG. 1, showing the chromatic aberration of magnification at the maximum half angle of view (106.000 deg/half angle). FIG. 5 is an explanatory diagram showing astigmatism and distortion of the wide-angle lens 100 shown in FIG. 6A, 6B, 6C, and 6D are explanatory diagrams showing lateral aberration of the wide-angle lens 100 shown in FIG. , 30°, 60° and 100° are shown for lateral aberration in the tangential (Y-direction) and sagittal (X-direction) directions.

3 to 6 show aberrations at wavelengths of 486 nm, 546 nm, and 656 nm with B, G, and R. FIG. As for the astigmatism shown in FIG. 5, S is attached to the characteristic in the sagittal direction, and T is attached to the characteristic in the tangential direction. Further, the distortion shown in FIG. 5 indicates the change ratio of the image between the imaging central portion and the peripheral portion, and it can be said that the smaller the absolute value of the numerical value representing the distortion, the higher the precision of the lens.

As shown in FIGS. 3 to 6, in the wide-angle lens 100 of this embodiment, spherical aberration, chromatic aberration of magnification, astigmatism (distortion), and lateral aberration are corrected to appropriate levels.

(Embodiment 2)
FIG. 7 is an explanatory diagram of the wide-angle lens 100 according to Embodiment 2 of the present invention. As shown in FIG. 7, the wide-angle lens 100 of this embodiment also has a front group 110, a diaphragm 80, a rear group 120, and an infrared cut filter 81 in order from the object side La to the image side Lb, as in the first embodiment. Prepare. The front group 110 is composed of a first lens 10, a second lens 20, and a third lens 30 in order from the object side La to the image side Lb.

The rear group 120 consists of a fourth lens 40, a fifth lens 50, and a sixth lens 60 in order from the object side La to the image side Lb. On the image side Lb of the sixth lens, a flat infrared cut filter 81, a translucent cover 82, and an imaging device 85 are arranged in order from the object side La to the image side Lb.

(lens configuration)
FIG. 8 is a diagram showing wide-angle lens 100 data according to the second embodiment. Note that the values shown in FIG. 8 are rounded off.

Since the wide-angle lens 100 of this embodiment satisfies the conditional expressions (1) to (11) described in the first embodiment, it has the same effect as the first embodiment.

In this form,
f0 = 1.277mm
R51=5.665mm
is. Therefore, R51/f0=4.436, which satisfies conditional expression (1).

In this form,
R51=5.665mm
R52=1.239mm
is. Therefore, (R51+R52)/(R51-R52)=1.560, which satisfies conditional expression (2).

In this form,
f0 = 1.277mm
f56=4.015mm
is. Therefore, f56/f0=3.144, which satisfies conditional expression (3).
meet.

In this form,
f0 = 1.277mm
f456=2.905mm
is. Therefore, f456/f0=2.275, which satisfies conditional expression (4).

In this form,
f0 = 1.277mm
f123=-2.453mm
is. Therefore, f123/f0=-1.921, which satisfies conditional expression (5).

In this form,
f123=-2.453mm
f456 = 2.905mm
is. Therefore, f123/f456=-0.844, which satisfies conditional expression (6).

In this form,
f0 = 1.277mm
d0=15.610mm
is. Therefore, d0/f0=12.225, which satisfies conditional expression (7).

In this form,
f0 = 1.277mm
f2=-2.750mm
is. Therefore, f2/f0=-2.154, which satisfies conditional expression (8).

In this form,
f0 = 1.277mm
f12=-1.422mm
is. Therefore, f12/f0=-1.113, which satisfies conditional expression (9).

In this form,
f0 = 1.277mm
R31=2.520mm
is. Therefore, R31/f0=1.973, which satisfies conditional expression (10).

In this form,
R31=2.520mm
R32=6.181mm
is. Therefore, (R31+R32)/(R31-R32)=-2.376, which satisfies conditional expression (11).

(Aberration characteristics of wide-angle lens 100)
FIG. 9 is an explanatory diagram showing spherical aberration of the wide-angle lens 100 shown in FIG. FIG. 10 is an explanatory diagram showing the chromatic aberration of magnification of the wide-angle lens 100 shown in FIG. 7, showing the chromatic aberration of magnification at the maximum half angle of view (106.000 deg/half angle). FIG. 11 is an explanatory diagram showing astigmatism and distortion of the wide-angle lens 100 shown in FIG. 12A, 12B, 12C, and 12D are explanatory diagrams showing lateral aberration of the wide-angle lens 100 shown in FIG. , 30°, 60° and 100° are shown for lateral aberration in the tangential (Y-direction) and sagittal (X-direction) directions.

As shown in FIGS. 9 to 12, in the wide-angle lens 100 of this embodiment, spherical aberration, chromatic aberration of magnification, astigmatism (distortion), and lateral aberration are corrected to appropriate levels.

(Embodiment 3)
FIG. 13 is an explanatory diagram of the wide-angle lens 100 according to Embodiment 3 of the present invention. As shown in FIG. 13, the wide-angle lens 100 of this embodiment also has a front group 110, a diaphragm 80, a rear group 120, and an infrared cut filter 81 in order from the object side La to the image side Lb, as in the first embodiment. Prepare. The front group 110 is composed of a first lens 10, a second lens 20, and a third lens 30 in order from the object side La to the image side Lb.

The rear group 120 consists of a fourth lens 40, a fifth lens 50, and a sixth lens 60 in order from the object side La to the image side Lb. On the image side Lb of the sixth lens, a flat infrared cut filter 81, a translucent cover 82, and an imaging device 85 are arranged in order from the object side La to the image side Lb. In this embodiment, the third lens 30 has a convex lens surface 31 on the object side La and a convex lens surface 32 on the image side Lb. Other basic configurations are the same as those of the first embodiment.

(lens configuration)
FIG. 14 is a diagram showing wide-angle lens 100 data according to the third embodiment. Note that the values shown in FIG. 14 are rounded off.

Since the wide-angle lens 100 of this embodiment satisfies the conditional expressions (1) to (10) described in the first embodiment, it has the same effect as the first embodiment.

In this form,
f0 = 1.437mm
R51=7.272mm
is. Therefore, R51/f0=5.061, which satisfies conditional expression (1).

In this form,
R51=7.272mm
R52=1.396mm
is. Therefore, (R51+R52)/(R51-R52)=1.475, which satisfies conditional expression (2).

In this form,
f0 = 1.437mm
f56=6.454mm
is. Therefore, f56/f0=4.492, which satisfies conditional expression (3).
meet.

In this form,
f0 = 1.437mm
f456=3.600mm
is. Therefore, f456/f0=2.506, which satisfies conditional expression (4).

In this form,
f0 = 1.437mm
f123=-6.428mm
is. Therefore, f123/f0=-4.474, which satisfies conditional expression (5).

In this form,
f123=-6.428mm
f456 = 3.600mm
is. Therefore, f123/f456=-1.785, which satisfies conditional expression (6).

In this form,
f0 = 1.437mm
d0 = 16.108mm
is. Therefore, d0/f0=11.211, which satisfies conditional expression (7).

In this form,
f0 = 1.437mm
f2=-3.360mm
is. Therefore, f2/f0=-2.338, which satisfies conditional expression (8).

In this form,
f0 = 1.437mm
f12=-1.710mm
is. Therefore, f12/f0=-1.190, which satisfies conditional expression (9).

In this form,
f0 = 1.437mm
R31=10.282mm
is. Therefore, R31/f0=2.617, which satisfies conditional expression (10).

(Aberration characteristics of wide-angle lens 100)
FIG. 15 is an explanatory diagram showing spherical aberration of the wide-angle lens 100 shown in FIG. FIG. 16 is an explanatory diagram showing the chromatic aberration of magnification of the wide-angle lens 100 shown in FIG. 13, showing the chromatic aberration of magnification at the maximum half angle of view (106.000 deg/half angle). FIG. 17 is an explanatory diagram showing astigmatism and distortion of the wide-angle lens 100 shown in FIG. 18A, 18B, 18C, and 18D are explanatory diagrams showing lateral aberration of the wide-angle lens 100 shown in FIG. , 30°, 55° and 100° are shown in the tangential direction (Y direction) and sagittal direction (X direction).

As shown in FIGS. 15 to 18, in the wide-angle lens 100 of this embodiment, spherical aberration, chromatic aberration of magnification, astigmatism (distortion), and lateral aberration are corrected to appropriate levels.

DESCRIPTION OF SYMBOLS 10... 1st lens, 20... 2nd lens, 30... 3rd lens, 40... 4th lens, 50... 5th lens, 60... 6th lens, 70... cemented lens, 80... diaphragm, 81... infrared cut filter , 85... Imaging element 100... Wide-angle lens 110... Front group 120... Rear group 850... Imaging surface

Claims (9)

Equipped with a front group, an aperture, and a rear group in order from the object side to the image side,
The front group is composed of a first lens, a second lens and a third lens in order from the most object side to the image side,
The rear group is composed of a fourth lens, a fifth lens and a sixth lens in order from the most object side to the image side,
The first lens has negative power and has a concave shape on the image side lens surface,
The second lens has negative power and has a concave shape on the image side lens surface,
the third lens has a positive power,
The fourth lens has positive power,
The fifth lens has a negative power, has a convex shape on the object side lens surface, and has a concave shape on the image side lens surface,
The sixth lens has a positive power and has a convex shape on the object-side lens surface and the image-side lens surface,
The fifth lens and the sixth lens are cemented lenses in which an image-side lens surface of the fifth lens and an object-side lens surface of the sixth lens are cemented together,
Assuming that the focal length of the entire lens system is f0 and the radius of curvature of the object-side lens surface of the fifth lens is R51, the following conditional expression: 2.000≦R51/f0≦10.000
A wide-angle lens characterized by satisfying Assuming that the radius of curvature of the object-side lens surface of the fifth lens is R51 and the radius of curvature of the image-side lens surface of the fifth lens is R52, the following conditional expression: 1.000≦(R51+R52)/(R51− R52) ≤ 3.000
2. The wide-angle lens according to claim 1, wherein: Assuming that the focal length of the entire lens system is f0 and the combined focal length of the fifth lens and the sixth lens is f56, the following conditional expression: 2.500≦f56/f0≦6.000
3. The wide-angle lens according to claim 1, wherein: Assuming that the focal length of the entire lens system is f0 and the combined focal length of the fourth lens, the fifth lens and the sixth lens is f456, the following conditional expression: 2.200≦f456/f0≦2.800
4. The wide-angle lens according to any one of claims 1 to 3, wherein: Assuming that the focal length of the entire lens system is f0 and the combined focal length of the first lens, the second lens and the third lens is f123, the following conditional expression −6.000≦f123/f0≦−1.300
5. The wide-angle lens according to any one of claims 1 to 4, wherein: Assuming that the combined focal length of the first lens, the second lens and the third lens is f123, and the combined focal length of the fourth lens, the fifth lens and the sixth lens is f456, the following conditional expression - 3.000≤f123/f456≤-0.500
6. The wide-angle lens according to any one of claims 1 to 5, wherein: Assuming that the focal length of the entire lens system is f0 and the total length of the entire lens system is d0, the following conditional expression: 11.000≤d0/f0≤15.000
7. The wide-angle lens according to any one of claims 1 to 6, wherein: Assuming that the focal length of the entire lens system is f0 and the focal length of the second lens is f2, the following conditional expression −2.450≦f2/f0≦−2.000
8. A wide-angle lens according to any one of claims 1 to 7, characterized in that: Assuming that the focal length of the entire lens system is f0 and the combined focal length of the first lens and the second lens is f12, the following conditional expression −1.300≦f12/f0≦−1.100
9. The wide-angle lens according to any one of claims 1 to 8, wherein:

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