JP2010276752A - Wide angle lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a wide angle lens having an f-value showing high brightness, sufficiently securing an angle of view, and satisfactorily correcting various aberrations while achieving miniaturization and reduction of weight. <P>SOLUTION: The wide angle lens aimed to form an image on an imaging element, in order from an object side, includes: a first lens having a negative meniscus shape, which turns a concave surface to an image side; a second lens having a negative meniscus shape, which turns a concave surface to the image side; a third lens having positive refractive power; an aperture stop; and a fourth lens having positive refractive power. The second lens includes aspherical surface on one side, and the fourth lens includes aspherical surfaces on both sides. By satisfying conditions: 2W>130°, -10.0<f1/f<-6.6, 1.8<f1/f2<5.0, 2.0<d2/f<4.5 (provided that 2W: entire angle of view, f: focal length of the entire system, f1: focal length of the first lens, f2: focal length of the second lens, d2: air distance on an optical axis between the first lens and the second lens), the angle of view is sufficiently secured and the various aberrations are satisfactorily corrected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a wide-angle lens mainly used in an imaging apparatus including a solid-state imaging device such as a monitoring camera and a vehicle-mounted camera.

Imaging lenses used for surveillance cameras, in-vehicle cameras, and the like are required to have good imaging performance over the entire screen while ensuring a wide angle of view. In addition, since the mounting space is often limited, it is required to be small and lightweight.
As wide-angle imaging lenses that may be able to meet these demands, for example, those described in Patent Documents 1 to 3 below are known.

JP 2003-195161 A JP 2004-029262 A JP 2005-345577 A

However, in the wide-angle lenses described in Patent Documents 2 and 3, in order to have high imaging performance, the glass spherical lens is mainly used, and the number of lenses increases to 5 to 7 and further increases, so that the above demand is satisfied. It is difficult to be satisfied.
Further, the wide-angle lens described in Patent Document 1 is known to have a reduced number of constituent lenses and to be downsized. However, the diameter of the first lens arranged closest to the object side is too large, or aberration is increased. Correction was not sufficient and it was difficult to satisfy high imaging performance over the entire screen.
Furthermore, when used as an in-vehicle monitor, a security camera lens, etc., in order to eliminate blind spots, a wide angle of view in which the total angle of view exceeds 180 degrees has been recently demanded.
In the present invention, in consideration of the problems of these conventional examples and recent requirements, the lens system is configured in consideration of mass productivity, and the optical system is required to be compact from the viewpoint of a monitoring camera or a vehicle-mounted camera. It is an object of the present invention to provide a wide-angle lens that realizes a low-cost and secures a good image quality and a desired angle of view.

A negative meniscus first lens having a concave surface facing the image side in order from the object side, a negative meniscus second lens having a concave surface facing the image side, a third lens having positive refractive power, an aperture stop, And a fourth lens having a positive refractive power, the second lens has a single aspherical shape, and the fourth lens has a double-sided aspheric shape,
Furthermore, the gist is to satisfy the following conditions.
2W> 130 °
−10.0 <f1 / f <−6.6
1.8 <f1 / f2 <5.0
2.0 <d2 / f <4.5
However,
2W: Full field angle f: Total system focal length f1: First lens focal length f2: Second lens focal length d2: Air spacing on the optical axis between the first lens and the second lens The first lens is The gist is that the second lens is formed of a glass material, the second lens is formed of a resin material, the second lens has an aspheric shape on the image side surface, and satisfies the following conditional expression.
−4.0 <f2 / f <−1.5
−2.5 <f12 / f <−1.3
1.0 <(r21 + r22) / (r21-r22) <2.0
However,
f: focal length of the entire system f2: focal length of the second lens f12: combined focal length of the first lens and the second lens r21: paraxial radius of curvature r22 on the object side of the second lens r22: image plane side of the second lens The third lens is made of a glass material, the fourth lens is made of a resin material, and satisfies the following conditional expression.
2.0 <f3 / f <7.0
2.0 <f4 / f <4.0
−1.4 <f4 / f2 <−0.5
However,
f: focal length of the entire system f2: focal length of the second lens f3: focal length of the third lens f4: focal length of the fourth lens The Abbe number of the material constituting the first lens with respect to the d-line is 40 or more, The Abbe number for the d-line of the material constituting the second lens is 50 or more, the Abbe number for the d-line of the material constituting the third lens is 40 or less, and the Abbe number for the d-line of the material constituting the fourth lens is The gist is that each is set to 50 or more.

According to the present invention, it is possible to achieve a wide-angle lens that ensures a good image quality and a desired angle of view while reducing the size of the optical system.

3 is a lens cross-sectional view of the wide-angle lens of Embodiment 1. FIG. FIG. 3 is an aberration diagram of the wide-angle lens of Embodiment 1. 6 is a lens cross-sectional view of a wide-angle lens according to Embodiment 2. FIG. FIG. 6 is an aberration diagram of the wide-angle lens of Embodiment 2. 6 is a lens cross-sectional view of a wide-angle lens according to Embodiment 3. FIG. FIG. 10 is an aberration diagram of the wide-angle lens of Embodiment 3. 6 is a lens cross-sectional view of a wide-angle lens of Embodiment 4. FIG. FIG. 6 is an aberration diagram of the wide-angle lens of Embodiment 4. 6 is a lens cross-sectional view of a wide-angle lens according to Embodiment 5. FIG. FIG. 10 is an aberration diagram of the wide-angle lens of Embodiment 5.

で表される。但しＲは近軸曲率半径、Ａ，Ｂ，Ｃ，Ｄ，Ｅは非球面係数、Ｋは円錐定数である。
前述の各条件式と数値実施例における諸数値との関係を表−１に示す。 Hereinafter, embodiments of a wide-angle lens of the present invention and an image pickup apparatus using the same will be described with reference to the drawings.
FIG. 1 is a lens cross-sectional view of the wide-angle lens of the first embodiment. FIG. 2 is an aberration diagram of the wide-angle lens of the first embodiment. In the first embodiment, the focal length is 0.801 mm, the F number is 2.60, the total angle of view is 196.6 °, and the back focus (the air conversion distance from the surface closest to the image side of the imaging lens to the imaging surface) is 2.071 mm. This is a wide-angle lens.
FIG. 3 is a lens cross-sectional view of the wide-angle lens of the second embodiment. FIG. 4 is an aberration diagram of the wide-angle lens of the second embodiment. The second embodiment is a wide-angle lens having a focal length of 0.794 mm, an F number of 2.60, a full field angle of 196.2 °, and a back focus of 1.58 mm.
FIG. 5 is a lens cross-sectional view of the wide-angle lens of the third embodiment. FIG. 6 is an aberration diagram of the wide-angle lens of Embodiment 3. The third embodiment is a wide-angle lens having a focal length of 0.806 mm, an F number of 2.60, a full field angle of 195.6 °, and a back focus of 1.52 mm.
FIG. 7 is a lens cross-sectional view of the wide-angle lens of the fourth embodiment. FIG. 8 is an aberration diagram of the wide-angle lens of the fourth embodiment. The fourth embodiment is a wide-angle lens having a focal length of 0.799 mm, an F number of 2.60, a total angle of view of 196.4 °, and a back focus of 2.955 mm.
FIG. 9 is a lens cross-sectional view of the wide-angle lens of the fifth embodiment. FIG. 10 is an aberration diagram of the wide-angle lens of Embodiment 5. Embodiment 5 is a wide-angle lens having a focal length of 0.800 mm, an F number of 2.60, a total angle of view of 196.3 °, and a back focus of 1.505 mm.
In the lens cross-sectional views of the embodiments, the left side is the subject side (object side), and the right side is the image side (imaging plane side). In the lens cross-sectional view, G0 is a wide angle lens, a first lens L1 having a negative refractive power (optical power = reciprocal of focal length), a second lens L2 having a negative refractive power, and a third lens having a positive refractive power. L3 includes a fourth lens L4 having a positive refractive power. SP is an aperture stop, which is located between the third lens L3 and the fourth lens.
G is a glass block designed in accordance with a crystal low-pass filter, an infrared cut filter, a protective glass for protecting the image sensor, and the like. IP is an image plane on which a photosensitive surface of a solid-state imaging device such as a CCD sensor or a CMOS sensor is arranged.
In this embodiment, the focus from an infinite object to a short-distance object is fixed at the pan focus position, and the wide-angle lens G0 is not extended, but the wide-angle lens G0 is extended to the object side or the imaging lens G0 is used. You may carry out by paying out one part among the some lenses which comprise.
In the aberration diagrams, (A) shows the amount of spherical aberration, (B) shows the amount of astigmatism, and (C) shows the amount of deviation with respect to the stereoscopic projection method. (A) shows the value for the d-line (587.56 nm). In (B), the solid line indicates the d-line value (ΔM) on the meridional image plane, the broken line indicates the d-line value (ΔS) on the sagittal image plane, and (C) indicates the value for the d-line. .
As for the amount of distortion shown in the item (C), a central projection method represented by y = f × tanW is used in a general camera lens. Here, y is the image height on the image sensor, and the angle of view is 2W. However, when the angle of view is close to or exceeds 180 °, the central projection method is not practical. Instead, a normal projection method (y = f × sinW), which is a fish-eye lens projection method, and an equidistant projection method are used. (Y = f × W), solid projection method (y = 2 × f × tan (W / 2)), equal solid angle projection method (y = 2 × f × sin (W / 2)), and the like. Adopted. This can be regarded as determining the compression ratio of the surrounding image when the center of the screen is used as a reference, and the wide-angle lens of this embodiment is mainly used for eliminating blind spots such as surveillance cameras and in-vehicle cameras. Since there are many cases, the amount of deviation with respect to the stereoscopic projection method having a low peripheral compression rate is shown.
Hereinafter, the configuration and operation of the wide-angle lens of this embodiment (the wide-angle lenses of Embodiments 1 to 5 are collectively referred to as the wide-angle lens of this embodiment) will be described.
The wide-angle lens G0 of the present embodiment has a convex object-side surface in which the absolute value of the refractive power of the object-side surface is smaller than that of the image-side surface in the order from the object side to the image side. It consists of a meniscus glass lens whose image side surface is convex toward the object side. In this way, by using the first lens L1 as a glass lens, it is possible to satisfy severe environmental performance that is applied to a monitoring camera or a vehicle-mounted camera.
The second lens L2 is formed of a meniscus resin lens (plastic lens) having a negative refractive power such that the concave surface faces the image side and the object side surface is convex. Thus, the second lens L2 has a meniscus shape, and the ratio of the center thickness to the thickness of the peripheral portion (deviation thickness ratio) is made as small as possible to improve the fluidity of the resin and to easily mold a desired shape and the like. can do.
A lens made of a resin material is superior to a lens made of glass in terms of molding stability, weight, and cost. Further, by taking advantage of the molding, a favorable image forming performance can be obtained with a small number of components by using a rotationally symmetric aspherical surface on the image side to increase the degree of freedom in design. On the other hand, the object side surface has a spherical shape that is looser than the image side surface.
This is a shape conscious of ghost due to surface reflection between the object-side surface of the second lens L2 and the concave peripheral portion on the image side of the first lens L1. By making the spherical shape as gentle as possible, the coating characteristic deposited on the object side of the second lens L2 is prevented from causing a large difference between the central portion and the peripheral portion, and the reflectance of the surface that is likely to cause ghosting Mitigating.
The third lens L3 is a glass lens having a positive refractive power, and the fourth lens L4 is a resin lens having a positive refractive power with a convex surface facing the image side. The fourth lens L4 made of a resin lens uses a rotationally symmetric aspherical surface on both sides (object side and image side) taking advantage of molding. In this way, good imaging performance can be obtained with a small number of components by expanding the degree of freedom from the spherical surface.
The fourth lens L4 is a lens having positive refractive power in which the image side surface is a strong convex surface and the object side surface is substantially flat. By adopting such a shape, the sensitivity near the aperture stop SP is relaxed, and the lens is easy to manufacture.
The aperture stop SP is disposed between the third lens L3 and the fourth lens L4. If the aperture stop SP is disposed on the image side of the fourth lens L4, it is not preferable because the lens system is enlarged, and if it is disposed between the second lens L2 and the third lens L3, the focal length is shortened. It is disadvantageous and not preferable. Therefore, by disposing the lens between the third lens L3 and the fourth lens L4 described above, it is possible to correct various aberrations and make the lens system compact.
As described above, the wide-angle lens according to the present embodiment achieves good imaging performance and a wide angle of view as an imaging optical system for an image sensor by an appropriate power arrangement and aspherical arrangement, and is downsized and reduced in cost. Has achieved. The conditions for constructing a bright lens while obtaining such effects in a well-balanced manner while achieving higher imaging performance will be described below.
The following are preferable conditions for the configuration as an optimum wide-angle lens.
2W> 130 ° (Condition 1)
Here, 2W indicates the maximum angle of view (full angle of view) that can be incident on the image sensor.
Conditional expression (1) is an expression relating to the diagonal angle of view of the wide-angle lens G0. If the diagonal angle of view is narrowed beyond the lower limit value of conditional expression (1), there will be many blind areas as surveillance cameras and in-vehicle cameras, which is not preferable.
More preferably, the numerical value range of the conditional expression (1) is set as in the following conditional expression (1a) to ensure a more preferable photographing range as a monitoring camera or a vehicle-mounted camera. It becomes possible.
2W> 180 ° (Condition 1a)
The following conditions are preferable for reducing the lens diameter while achieving a wide angle of view.
−10.0 <f1 / f <−6.6 (Condition 2)
Here, f1 indicates the focal length of the first lens L1, and f indicates the focal length of the entire system.
Conditional expression (2) is a conditional expression regarding the focal length of the first lens L1 and the focal length of the entire system. Exceeding the upper limit value of conditional expression (2) is advantageous for making the first lens L1 compact, but is not preferable because various aberrations increase and correction with the subordinate lens becomes difficult. If the lower limit of conditional expression (2) is exceeded, a sufficient amount of back focus cannot be secured, and further, the first lens L1 is enlarged, which is not preferable for downsizing.
In view of the above contents, more preferably, by setting the numerical range of conditional expression (2) as in the following conditional expression (2a), it is possible to reduce the overall length and ensure high imaging performance. It becomes.
−8.9 <f1 / f <−6.6 (Condition 2a)
The following conditions are preferable for good aberration correction of the optical system while facilitating manufacture.
1.8 <f1 / f2 <5.0 (Condition 3)
Here, f1 indicates the focal length of the first lens L1, and f2 indicates the focal length of the second lens L2.
Conditional expression (3) is a conditional expression regarding the focal length of the first lens L1 and the focal length of the second lens L2. If the lower limit value of conditional expression (3) is exceeded, the negative refractive power of the first lens L1 becomes strong, the concave surface of the image side surface of the first lens L1 becomes tight, making it difficult to manufacture, and the amount of various aberrations increases. However, it is not preferable because correction with a dependent lens becomes difficult. If the upper limit of conditional expression (3) is exceeded, the negative refractive power of the second lens L2 becomes strong, the ratio of the center thickness to the peripheral thickness increases, and molding becomes difficult. Furthermore, since the refractive power of the second lens L2 is increased, the sensitivity is increased, and the eccentricity allowable amount at the time of incorporation during manufacturing becomes strict, which is not preferable.
More preferably, the numerical value range of conditional expression (3) is set as shown in the following conditional expression (3a) so that various aberrations can be favorably corrected and high imaging can be performed. It becomes possible to ensure performance.
1.8 <f1 / f2 <3.5 (Condition 3a)
The following conditions are preferable for good aberration correction of the optical system while facilitating manufacture.
2.0 <d2 / f <4.5 (Condition 4)
Here, d2 represents the air space on the optical axis between the first lens L1 and the second lens L2, and f represents the focal length of the entire system.
Conditional expression (4) is a conditional expression related to the air distance between the first lens L1 and the second lens L2 and the focal length of the entire system. When the lower limit value of conditional expression (4) is exceeded, the air space between the first lens L1 and the second lens L2 becomes small, and the wide-angle lens G0 of the present embodiment that secures the back focus inevitably has an image of the first lens L1. The side surface is a strong concave surface, which is not preferable because the surface and the object side surface of the second lens L2 interfere with each other or enter the image side surface of the first lens L1. If the upper limit of conditional expression (4) is exceeded, various aberrations, particularly distortion and field curvature, increase, and high imaging performance cannot be obtained. Furthermore, since the total length becomes long, it is not preferable from the viewpoint of compactness.
More preferably, the numerical range of conditional expression (4) is set as in conditional expression (4a) below to ensure the back focus while keeping the overall length compact and even higher. Imaging performance can be obtained.
2.0 <d2 / f <3.8 (Condition 4a)
The following conditions are preferable for achieving good aberration correction of the optical system while achieving a wide angle of view.
−4.0 <f2 / f <−1.5 (Condition 5)
Here, f2 indicates the focal length of the second lens L2, and f indicates the focal length of the entire system.
Conditional expression (5) is a conditional expression regarding the focal length of the second lens L2 and the focal length of the entire system. If the upper limit value of conditional expression (5) is exceeded, the curvature of the image plane side of the second lens L2 becomes too small, and the curvature of the object side of the adjacent third lens L3 becomes tight accordingly. It is not preferable also from a viewpoint. If the lower limit of conditional expression (5) is exceeded, negative refracting power will be insufficient, making it difficult to correct chromatic aberration of magnification.
In view of the above contents, more preferably, by setting the numerical range of conditional expression (5) as in the following conditional expression (5a), it is possible to ensure high imaging performance.
−3.8 <f2 / f <−2.3 (Condition 5a)
The following are preferable conditions for ensuring a proper incident angle on the image plane while achieving a wide angle of view.
-2.5 <f12 / f <-1.3 (Condition 6)
Here, f12 represents the combined focal length of the first lens L1 and the second lens L2, and f represents the focal length of the entire system.
Conditional expression (6) is a conditional expression related to the combined focal length of two negative lenses arranged on the object side. If the upper limit value of conditional expression (6) is exceeded, the negative power becomes strong, the curvature of each surface of the negative lens becomes too strong, and manufacturing becomes difficult. In addition, it is difficult to sufficiently correct the curvature of field generated on the surface of strong curvature with an aspherical surface, which is not preferable for obtaining good resolution performance. If the lower limit of conditional expression (6) is exceeded, the negative refractive power will be insufficient, and it will be difficult to bend light rays with a large incident angle. For example, an ultra-wide angle with an angle of view exceeding 180 ° will be achieved. It is difficult to do so, which is not preferable. In addition, since the degree of the retrofocus type, which is a general configuration of a wide-angle lens, is weakened, the incident angle to the image plane becomes tight, which is not suitable for an electronic image pickup device such as a CCD.
In view of the above contents, more preferably, the numerical range of conditional expression (6) is set as in the following conditional expression (6a), so that a wide angle of view is achieved and proper incidence on the image plane is achieved. An angle can be secured.
-2.0 <f12 / f <-1.3 (Condition 6a)
The following conditions are preferable for achieving good aberration correction of the optical system while achieving a wide angle of view.
1.0 <(r21 + r22) / (r21−r22) <2.0 (conditional expression 7)
Here, r21 represents the paraxial radius of curvature of the second lens L2 on the object side, and r22 represents the paraxial radius of curvature of the second lens L2 on the image side.
Conditional expression (7) is a conditional expression regarding the paraxial curvature radius on the object side and the paraxial curvature radius on the image plane side of the second lens L2. If the lower limit value of conditional expression (7) is exceeded, the meniscus shape cannot be maintained, which is not preferable from the viewpoint of coating properties that contribute to fluidity and ghosting during molding. On the other hand, if the upper limit value of conditional expression (7) is exceeded, the aberrations of various aberrations increase, and in particular, the shape becomes a shape that increases the divergence of the peripheral portion, resulting in curvature of field, which makes it difficult to sufficiently correct with an aspherical surface. It is not preferable for obtaining good resolution performance.
In view of the above contents, more preferably, the numerical range of conditional expression (7) is set as in the following conditional expression (7a) to ensure the back focus while keeping the overall length compact and even higher. Imaging performance can be obtained.
1.0 ≦ (r21 + r22) / (r21−r22) <1.3 (Condition 7a)
The following conditions are preferable for good aberration correction of the optical system while facilitating manufacture.
2.0 <f3 / f <7.0 (Condition 8)
Here, f3 indicates the focal length of the third lens L3, and f indicates the focal length of the entire system.
Conditional expression (8) is a conditional expression regarding the focal length of the third lens L3 and the focal length of the entire system. Exceeding the upper limit of conditional expression (8) is not preferable because the positive refractive power is insufficient and correction of chromatic aberration of magnification becomes difficult. If the lower limit value of conditional expression (8) is exceeded, the curvature of the object side surface of the third lens L3 becomes too small, which makes manufacturing difficult and is not preferable.
In view of the above contents, more preferably, by setting the numerical range of conditional expression (8) as in the following conditional expression (8a), it is possible to ensure high imaging performance.
3.3 <f3 / f <5.7 (Condition 8a)
The following conditions are preferable for good aberration correction of the optical system while facilitating manufacture.
2.0 <f4 / f <4.0 (Condition 9)
Here, f4 indicates the focal length of the fourth lens L4, and f indicates the focal length of the entire system.
Conditional expression (9) is a conditional expression regarding the focal length of the fourth lens L4 and the focal length of the entire system. If the upper limit value of conditional expression (9) is exceeded, the positive refractive power becomes too small, which makes it difficult to correct various aberrations. If the lower limit of conditional expression (9) is exceeded, the curvature of the image side surface of the fourth lens L4 becomes too tight, which is not preferable from the viewpoint of manufacturing.
In view of the above contents, more preferably, by setting the numerical range of conditional expression (9) as in the following conditional expression (9a), it is possible to ensure high imaging performance.
2.2 <f4 / f <3.5 (Condition 9a)
The following conditions are preferable for maintaining good back focus fluctuation due to temperature fluctuation even when a resin lens is used.
−1.4 <f4 / f2 <−0.5 (Condition 10)
Here, f4 indicates the focal length of the fourth lens L4, and f2 indicates the focal length of the second lens L2.
Conditional expression (10) is a conditional expression regarding the focal length of the fourth lens L4 using a resin lens and the focal length of the second lens L2 using a resin lens. The use of resin lenses is lightweight and inexpensive, and since aspherical surfaces are inexpensive and can be used, it is effective in improving optical performance, but the thermal expansion coefficient is one order of magnitude larger than that of glass lenses. Variation in image plane position due to the problem is often a problem. Conditional expression (10) defines a preferable focal length ratio in order to suppress performance fluctuations due to temperature changes between the negative resin lens and the positive resin lens with the diaphragm interposed therebetween. If the upper limit of conditional expression (10) is exceeded or less than the lower limit, the ratio of the focal lengths of the second lens L2 and the fourth lens L4 is lost, and the image plane position at the time of temperature fluctuation is not preferable.
In view of the above contents, more preferably, by setting the numerical range of the conditional expression (10) as in the following conditional expression (10a), it is possible to ensure high imaging performance.
−1.1 <f4 / f2 <−0.7 (Condition 10a)
The numerical data of numerical examples 1 to 5 corresponding to the first to fifth embodiments are shown below. In each numerical example, i indicates the order of the surfaces from the object side, ri is the radius of curvature of the i-th surface, di is the distance between the i-th surface and the (i + 1) -th surface, and ni and νi are for the d-line, respectively. Refractive index and Abbe number are shown. The two surfaces closest to the image side correspond to a crystal low-pass filter, protective glass, and the like, and are glass blocks G provided by design. The aspherical shape is when the displacement in the optical axis direction at the position of the height H from the optical axis is x with respect to the surface vertex.

It is represented by Where R is a paraxial radius of curvature, A, B, C, D, and E are aspherical coefficients, and K is a conic constant.
Table 1 shows the relationship between the above-described conditional expressions and various numerical values in the numerical examples.

Unit mm
・ Surface data
i r d n ν
1: 14.480 0.700 1.883 40.7
2: 3.510 2.076
3: 68.500 0.700 1.530 56.2
4 *: 1.545 1.324
5: 4.700 2.000 1.946 17.9
6: -14.600 1.415
7 (Aperture): ∞ 0.473
8 *: 8.200 1.950 1.530 56.2
9 *: -1.250 0.671
10: ∞ 0.800 1.516 64.1
11: ∞ 0.870
Image plane: ∞
* Aspherical

・ Aspherical surface number K A B C D
4: -0.890862 -1.18929E-02 2.07955E-03 -2.79961E-04 1.34065E-05
8: 0.023454 -1.16328E-01 1.87588E-01 -2.72991E-01 1.79544E-01
9: -0.548051 4.03412E-02 -1.31128E-02 6.56598E-03 -3.48417E-04

・ Various focal length 0.801mm
F number 2.6
Angle of view 196.6 °
Image height 1.826mm
Total lens length 13.663mm
Back focus (in air) 2.071mm

Unit mm
・ Surface data
i r d n ν
1: 9.620 0.700 1.883 40.7
2: 3.472 2.960
3: 595.000 0.700 1.530 56.2
4 *: 1.000 1.230
5: 2.483 1.820 1.946 17.9
6: 53.670 0.500
7 (Aperture): ∞ 0.590
8 *: 3.050 1.800 1.530 56.2
9 *: -1.350 0.185
10: ∞ 0.800 1.516 64.1
11: ∞ 0.870
Image plane: ∞
* Aspherical

・ Aspherical surface number K A B C D
4: -0.953449 2.33363E-03 1.24943E-02 -2.29485E-03 5.79133E-04
8: -20.641275 5.19695E-03 2.17165E-03 -1.33977E-02 2.17711E-03
9: -0.734183 4.59225E-02 -2.06950E-02 1.25146E-02 -3.47812E-03

・ Various focal length 0.794mm
F number 2.60
Angle of view 196.2 °
Image height 1.826mm
Total lens length 12.155mm
Back focus (in air) 1.580mm

Unit mm
・ Surface data
i r d n ν
1: 16.000 1.190 1.772 49.5
2: 3.840 1.735
3: 14.000 0.700 1.530 56.2
4 *: 1.116 1.630
5: 2.960 1.790 1.946 17.9
6: -90.090 0.500
7 (Aperture): ∞ 0.469
8 *: 5.200 1.780 1.530 56.2
9 *: -1.090 0.125
10: ∞ 0.800 1.516 64.1
11: ∞ 0.870
Image plane: ∞
* Aspherical

・ Aspherical surface number K A B C D
4: -0.670226 -2.61862E-02 3.58846E-03 2.18841E-03 -9.97810E-04
8: -0.008604 -1.85625E-01 1.36483E-01 -1.82360E-01 2.23464E-02
9: -0.429375 6.94270E-02 4.27673E-03 -1.54886E-02 8.38039E-03

・ Various focal length 0.806mm
F number 2.60
Angle of view 195.6 °
Image height 1.826mm
Total lens length 11.589mm
Back focus (in air) 1.520mm

Unit mm
・ Surface data
i r d n ν
1: 12.830 0.700 1.772 49.5
2: 3.534 2.225
3: 14.450 0.700 1.530 56.2
4 *: 1.334 2.330
5: 100.000 1.7895 1.923 20.8
6: -4.317 1.053
7 (Aperture): ∞ 0.605
8 *: -3.600 1.410 1.530 56.2
9 *: -1.180 1.560
10: ∞ 0.800 1.516 64.1
11: ∞ 0.870
Image plane: ∞
* Aspherical

・ Aspherical surface number K A B C D
4: -5.911760 1.24628E-01 -2.60747E-02 2.51823E-03 6.65500E-04
8: 0.035179 -2.36410E-01 1.71478E-01 -2.55587E-01 1.62313E-01
9: -0.690941 2.05088E-02 -1.02249E-01 7.61640E-02 -2.46762E-02

-Various data focal length 0.799mm
F number 2.60
Angle of view 196.4 °
Image height 1.826mm
Lens total length 14.0425mm
Back focus (in air) 2.955mm

Unit mm
・ Surface data
i r d n ν
1: 12.100 0.700 1.772 49.5
2: 3.660 2.450
3: 57.940 0.700 1.530 56.2
4 *: 1.070 1.290
5: 2.693 1.810 1.946 17.9
6: 55.295 0.500
7 (Aperture): ∞ 0.620
8 *: 2.850 1.730 1.530 56.2
9 *: -1.250 0.110
10: ∞ 0.800 1.516 64.1
11: ∞ 0.870
Image plane: ∞
* Aspherical

・ Aspherical surface number K A B C D
4: -1.025000 1.82300E-02 5.81200E-03 -1.66000E-03 4.75500E-04
8: -37.318400 6.57800E-02 -6.36500E-02 3.31200E-02 -8.13600E-03
9: -0.858600 4.74600E-02 -2.28700E-02 1.61300E-02 -3.78900E-03

-Various data focal length 0.800mm
F number 2.60
Angle of view 196.3 °
Image height 1.826mm
Total lens length 11.58mm
Back focus (in air) 1.505mm

According to the wide-angle lens of the present embodiment described above, a wide-angle lens that is suitable for an imaging system using a solid-state imaging device, particularly a surveillance camera, an in-vehicle camera, and the like, requires high optical performance, and has a bright F value. realizable.

G0 Wide-angle lens L1 First lens L2 Second lens L3 Third lens L4 Fourth lens SP Aperture stop IP Image plane G Glass block dd line ΔS Sagittal image plane ΔM Meridional image plane

Claims (4)

A negative first meniscus lens having a concave surface facing the image side in order from the object side;
A negative meniscus second lens having a concave surface facing the image side;
A third lens having a positive refractive power;
An aperture stop,
A fourth lens having a positive refractive power,
The second lens has a single aspherical shape, and the fourth lens has a double-sided aspheric shape,
Furthermore, the wide angle lens characterized by satisfying the following conditions.
2W> 130 °
−10.0 <f1 / f <−6.6
1.8 <f1 / f2 <5.0
2.0 <d2 / f <4.5
However,
2W: Total angle of view f: Total system focal length f1: First lens focal length f2: Second lens focal length d2: Air spacing on the optical axis between the first lens and the second lens The first lens is made of a glass material, the second lens is made of a resin material, the second lens has an aspheric shape on the image side surface, and satisfies the following conditions: The wide-angle lens according to claim 1.
−4.0 <f2 / f <−1.5
−2.5 <f12 / f <−1.3
1.0 <(r21 + r22) / (r21-r22) <2.0
However,
f: focal length of the entire system f2: focal length of the second lens f12: combined focal length of the first lens and the second lens r21: paraxial radius of curvature r22 on the object side of the second lens r22: image plane side of the second lens Paraxial radius of curvature 3. The wide-angle lens according to claim 1, wherein the third lens is made of a glass material, the fourth lens is made of a resin material, and satisfies the following conditions.
2.0 <f3 / f <7.0
2.0 <f4 / f <4.0
−1.4 <f4 / f2 <−0.5
However,
f: focal length of the entire system f2: focal length of the second lens f3: focal length of the third lens f4: focal length of the fourth lens The Abbe number of the material constituting the first lens with respect to the d-line is 40 or more, the Abbe number with respect to the d-line of the material constituting the second lens is 50 or more, and the Abbe number of the material constituting the third lens with respect to the d-line The wide-angle lens according to any one of claims 1 to 3, wherein an Abbé number with respect to the d-line of the material constituting the fourth lens is set to 50 or less.

Images