JP6356535B2 - Imaging lens and imaging apparatus - Google Patents

Description

  The present invention relates to a single-focus wide-angle imaging lens used in an imaging apparatus equipped with a solid-state imaging device, such as a monitoring camera and an in-vehicle camera, and an imaging apparatus using the imaging lens.

  Imaging devices such as CCDs and CMOSs that constitute imaging devices such as surveillance cameras and in-vehicle cameras are becoming smaller and higher in pixel year by year, and accordingly, imaging lenses are also required to be smaller and have higher performance. It has become like this.

  In recent years, technologies for recognizing objects and white lines have begun to spread in surveillance cameras and in-vehicle cameras, and it is expected that the microcomputer responsible for image processing will generate heat, so high weather resistance near the image sensor is required. Has been.

The following Patent Documents 1, 2, and 3 have been proposed as single-focus wide-angle imaging lenses that may be able to meet these demands. However, since the single focus lenses described in Patent Documents 1, 2, and 3 are compatible with conventional imaging devices and image processing systems, they cannot cope with the increase in the number of pixels and the heat generation of the electrical system.

JP 2008-268268 A JP 2009-008867 A JP 2010-054646 A

  The present invention has been made in view of the above points, and an object of the present invention is to achieve a sufficiently wide angle while having high optical performance that can be applied to an image sensor with an increasing number of pixels. Another object of the present invention is to provide an imaging lens having high weather resistance that can cope with heat generation of an electric system while being small and light, and an imaging device using the imaging lens.

To achieve the above object, in order from the object side, it is formed by a glass material, a first lens having a negative refractive power, is formed of a resin material, and a second lens having a negative refractive power, a glass material is formed, a third lens having a positive refractive power, an aperture stop, is formed of a resin material, and a fourth lens having a positive refractive power and a fifth lens formed of a glass material, said first When the focal length of the two lenses is f2, and the focal length of the fourth lens is f4, the following conditional expression (1) is satisfied .
−1.1 <f2 / f4 <−0.9 (1)

Preferably , at least one lens surface of the second lens and the fourth lens has an aspherical shape.

  More preferably, the first lens has a convex surface facing the object side, the third lens has a convex surface facing the object side, and the fourth lens has a convex surface facing the image side.

−1.1 <f2 / f4 <−0.9 (1)
More preferably, when the distance from the image plane side surface of the fifth lens to the imaging plane is Bf and the focal length of the entire imaging lens system is f, the following conditional expression (2) is satisfied. Features.

Bf / f ≧ 0.7 (2 )

  More preferably, the third lens is configured such that the Abbe number with respect to d-line of the material constituting the first lens is 40 or more, and the Abbe number with respect to d-line of the material constituting the second lens is 50 or more. The Abbe number with respect to the d-line of the material is set to 40 or less, and the Abbe number with respect to the d-line of the material constituting the fourth lens is set to 50 or more.

  More preferably, the following conditional expression (3) is satisfied when the total angle of view of light rays incident on the horizontal image height position on the imaging plane is 2 W.

2W ≧ 180 ° (3)
In order to solve the above-described problems, an imaging apparatus according to the present invention includes any one of the imaging lenses described above and an imaging element that converts an optical image formed by the imaging lens into an electrical signal.

  According to the present invention, a wide angle is achieved while having a high optical performance in which various aberrations are well corrected by the five-lens configuration, and a high weather resistance that can cope with heat generation of an electric system while being small and lightweight. It is possible to provide an imaging lens having the same and an imaging apparatus using the imaging lens. As a result, a compact wide-angle imaging lens that can be mounted on a surveillance camera or a vehicle-mounted camera can be realized.

It is a figure which shows the basic composition of the imaging lens of embodiment of this invention. 2 is a diagram illustrating a configuration of an imaging lens employed in Example 1. FIG. In Example 1, it is an aberrational figure which shows spherical aberration, distortion aberration, and astigmatism. 6 is a diagram illustrating a configuration of an imaging lens employed in Example 2. FIG. In Example 2, it is an aberrational figure which shows spherical aberration, distortion aberration, and astigmatism. 6 is a diagram illustrating a configuration of an imaging lens employed in Example 3. FIG. In Example 3, it is an aberrational figure which shows spherical aberration, distortion aberration, and astigmatism. 6 is a diagram illustrating a configuration of an imaging lens employed in Example 4. FIG. In Example 4, it is an aberrational figure which shows spherical aberration, a distortion aberration, and astigmatism. 6 is a diagram illustrating a configuration of an imaging lens employed in Example 5. FIG. FIG. 10 is an aberration diagram showing spherical aberration, distortion, and astigmatism in Example 5. 10 is a diagram illustrating a configuration of an imaging lens employed in Example 6. FIG. In Example 6, it is an aberrational figure which shows spherical aberration, a distortion aberration, and astigmatism. It is a figure which shows the basic composition of the imaging device of this embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the lens configuration of the embodiment in an optical section. In these embodiments, in order from the object side, the first lens 110, the second lens 120, the third lens 130, the aperture stop 140, the fourth lens 150, the fifth lens 160, a CCD (Charge Coupled Device) and a CMOS (Complementary Mental). This is a single-focus imaging lens 100 having a five-lens configuration in which a light receiving surface (imaging plane) 170 of an imaging element 210 such as an −Oxide Semiconductor device) is disposed.

  In the imaging lens embodying the present invention, five lenses are, in order from the object side, a first lens 110 having a negative refractive power, a second lens 120 having a negative refractive power, and a third lens having a positive refractive power. 130, an aperture stop 140, a fourth lens 150 having a positive refractive power, and a fifth lens 160. Moreover, 1 (R1) -11 (R10) of FIG. 1 is a surface number of each component.

  The aperture stop 140 is disposed between the third lens 130 and the fourth lens 150. Disposing the aperture stop 140 on the image side of the fourth lens 150 is not preferable because the lens system becomes large, and disposing it between the second lens 120 and the third lens 130 is disadvantageous for increasing Bf. It is not preferable. Therefore, by disposing the lens between the third lens 130 and the fourth lens 150 described above, it is possible to correct various aberrations and make the lens system compact.

  Since the fifth lens 160 is formed of a glass material, it is possible to take measures against heat generation from the microcomputer responsible for image processing. In addition, since at least one lens surface has an aspherical shape, aberration correction is facilitated, and good resolution performance can be obtained while being small.

  By forming the second lens 120 and the fourth lens 150 from a resin material, weight reduction and cost reduction can be realized and an aspherical shape can be easily manufactured. Since these lenses are formed in an aspherical shape, aberration correction is easy, and it is possible to obtain good resolution performance while being small.

  In general, a resin material has a large change in refractive index and shape due to a temperature change as compared with a glass material, and its refractive power is small at a high temperature and large at a low temperature. Therefore, the second lens 120 has a negative refractive power, and the fourth lens 150 has a positive refractive power, so that the variation in refractive power due to the change in shape and refractive index is canceled out, and the focal length in the entire lens system. As a result, desired performance can be obtained even in a wide temperature range.

Further, it is preferable that the first lens 110 has a convex surface facing the object side, the third lens 130 has a convex surface facing the object side, and the fourth lens 150 has a convex surface facing the image side.
Accordingly, the first lens 110 can make light from the object side incident at a wide angle of view by directing the convex surface toward the object side. In the third lens 130 having positive refractive power, the convex surface is directed toward the object side, and in the fourth lens 150, the convex surface is directed toward the image side, so that the sensitivity near the aperture stop 140 is relaxed and easy to manufacture. The imaging lens 100 is obtained.

When the focal length of the second lens 120 at the d line is f2 (mm) and the focal length of the fourth lens 150 at the d line is f4 (mm), the following conditional expression (1) is satisfied. preferable.
0.9 <| f2 / f4 | <1.1 (1)
By designing so as to satisfy such conditions, the power ratio (focal length ratio) of the second lens 120 and the fourth lens 150 is set to about 1: 1 (within a range of 0.9 to 1.1), and the temperature is set. The change accompanying the change can be offset between the resin lenses.

The imaging lens 100 is preferably configured to satisfy the conditional expression (2).
Bf / f ≧ 0.7 (2)
However, the distance from the image plane side surface of the fifth lens to the imaging plane is Bf, and the focal length of the entire imaging lens system is f.

  Conditional expression (2) relates the ratio of the distance from the image plane side surface of the fifth lens to the imaging plane with respect to the focal length of the entire imaging lens system. If the lower limit value of conditional expression (2) is exceeded, the ratio of Bf to f becomes small, so that an indispensable device such as an IR cut filter or a low-pass filter cannot be inserted, and docking with the image sensor becomes difficult.

  In addition, by forming the third lens 130 from a glass material, a material having a wide Abbe number can be selected, and as a result, the lateral chromatic aberration can be favorably corrected. Specifically, an advantageous effect for correcting chromatic aberration generated in the first lens 110 and the second lens 120 is obtained by using a glass material having a high Abbe number for the third lens 130.

  In addition, the imaging lens 100 is preferably configured such that the Abbe number of the material constituting the first lens 110 with respect to the d-line is 40 or more, the Abbe number of the material constituting the second lens 120 with respect to the d-line is 50 or more, and the third lens. The Abbe number with respect to the d-line of the material constituting 130 is set to 40 or less, and the Abbe number with respect to the d-line of the material constituting the fourth lens 150 is set to 50 or more.

  As a result, the Abbe relative to the d-line of the material constituting the first lens 110 and the second lens 120 of the negative lens located closer to the object side than the aperture stop 140 and the fourth lens 150 of the positive lens located closer to the image side than the aperture stop 140. The larger the number, the smaller the chromatic aberration of magnification generated in the first lens 110, the second lens 120, and the fourth lens 150. Similarly, the smaller the Abbe number of the material constituting the third lens 130 of the positive lens located on the object side than the aperture stop 140 is, the better the chromatic aberration of magnification can be corrected.

  Further, by forming the first lens 110 with a glass material, it is possible to satisfy severe environmental performance such as physical durability and chemical durability applied to a monitoring camera or a vehicle-mounted camera.

The imaging lens 100 is preferably configured to satisfy the conditional expression (3).
2W ≧ 180 ° (3)
However, 2W is the total angle of view of light rays incident on the horizontal image height position on the imaging plane.

  By setting the numerical value range of the conditional expression (3), it is possible to ensure a wider shooting range as a monitoring camera or a vehicle-mounted camera.

  The aspherical shape of the lens described in the following numerical examples is positive in the direction from the object side to the image plane side, k is a conical coefficient, A is a fourth-order aspheric coefficient, B Is a 6th-order aspheric coefficient, C is an 8th-order aspheric coefficient, and D is a 10th-order aspheric coefficient. h represents the height of the light beam, c represents the reciprocal of the central radius of curvature, and Z represents the depth from the tangent plane with respect to the surface vertex.

以下に、撮像レンズ１００の具体的な数値による実施例１〜６を示す。実施例１〜６の数値実施例において、焦点距離、Ｆ値、像高、レンズ全長、バックフォーカスは次の表１に記載の通りである。また、同じく実施例１〜６の数値実施例において、条件式（１）〜（３）の数値データは、次の表２に記載の値になる。

Examples 1 to 6 according to specific numerical values of the imaging lens 100 are shown below. In the numerical examples of Examples 1 to 6, the focal length, F value, image height, total lens length, and back focus are as shown in Table 1 below. Similarly, in the numerical examples of Examples 1 to 6, the numerical data of the conditional expressions (1) to (3) are the values described in Table 2 below.

Various data

Conditional expression

  The basic configuration of the imaging lens 100A in Embodiment 1 is shown in FIG. 2, each numerical data (setting value) is shown in Tables 3 and 4, and the aberration diagram showing spherical aberration, distortion aberration, and astigmatism is shown in FIG. Respectively.

  As shown in FIG. 2, the first lens 110 has a meniscus shape with a convex surface facing the object side, the second lens 120 has a meniscus shape with a convex surface facing the object side, and the third lens 130 has a flat surface with the convex surface facing the object side. The fourth lens 150 disposed on the image side of the aperture stop 140 has a biconvex shape with a convex surface facing the image side, and the fifth lens 160 has a meniscus shape with the convex surface facing the image side. The second lens 120 has an aspheric surface on both sides, the fourth lens 150 has an aspheric surface on one side, and the fifth lens 160 has an aspheric surface on one side.

  Further, as shown in FIG. 2, the distance between the R1 surface 1 and the R2 surface 2 that is the thickness of the first lens 110 is D1, and the distance from the R2 surface 2 of the first lens 110 to the R3 surface 3 of the second lens 120. D2, the distance between the R3 surface 3 and the R4 surface 4 that is the thickness of the second lens 120, D3, the distance between the R4 surface 4 of the second lens 120 and the R5 surface 5 of the third lens 130, D4, The distance between the R5 surface 5 and the R6 surface 6 having a thickness of 130 is D5, the distance between the R6 surface 6 of the third lens 130 and the surface 7 of the aperture stop 140 is D6, the surface 7 of the aperture stop 140 and the fourth lens 150. The distance between the R7 surface 8 is D7, the distance between the R7 surface 8 and the R8 surface 9 which is the thickness of the fourth lens 150 is D8, and the distance between the R8 surface 9 of the fourth lens 150 and the R9 surface 10 of the fifth lens 160 is The distance is D9 and the thickness of the fifth lens 160 is the R9 surface 10 and the R10 surface 1 The distance between D10, the distance to the R10 surface 11 and the image plane 170 of the fifth lens 160 and D11. In the following Examples 2 to 5, R1 surface 1 to R10 surface 11 and D1 to D11 mean the same distance.

Table 3 shows the stop corresponding to each surface number of the imaging lens 100A in Example 1, the radius of curvature R, the interval D, the refractive index Nd, and the Abbe number νd of each lens. In Table 3, the surface with * in the surface number indicates an aspherical shape. Table 4 shows the aspheric coefficient of the predetermined surface.
<Numerical Example 1>

図３は、実施例１において、図３（Ａ）が球面収差（左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm）を、図３（Ｂ）が非点収差（実線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのサジタル光線、点線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのタンジェンシャル光線）を、図３（Ｃ）が歪曲収差（435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmが重なっている）をそれぞれ示している。図３（Ｂ）、（Ｃ）の縦軸は半画角ωを表し、図３（Ｂ）中、実線Ｓはサジタル像面の値、破線Ｔはタンジェンシャル像面の値をそれぞれ示している（図５、７、９、１１、１３においても同様である）。図３からわかるように、実施例１によれば、球面、歪曲、非点の諸収差が良好に補正され、結像性能に優れた撮像レンズ１００Ａが得られる。

3A shows a spherical aberration (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, 656.3 nm from the left) and FIG. 3B shows an astigmatism (solid line: left) in Example 1. 35.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm sagittal rays, dotted line: 435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm tangential rays from the left), Figure 3 (C) Distortion aberrations (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, and 656.3 nm overlap) are shown. 3B and 3C, the vertical axis represents the half field angle ω. In FIG. 3B, the solid line S represents the sagittal image plane value, and the broken line T represents the tangential image plane value. (The same applies to FIGS. 5, 7, 9, 11, and 13). As can be seen from FIG. 3, according to the first embodiment, the imaging lens 100 </ b> A having excellent imaging performance can be obtained in which various spherical, distorted, and astigmatism aberrations are satisfactorily corrected.

  The basic configuration of the imaging lens 100B in Embodiment 2 is shown in FIG. 4, each numerical data (setting value) is shown in Tables 5 and 6, and the aberration diagram showing spherical aberration, distortion aberration, and astigmatism is shown in FIG. Respectively.

  The imaging lens 100B according to the second embodiment is designed for the purpose of shortening the back focus and reducing the size of the first embodiment.

  As shown in FIG. 4, the first lens 110 has a meniscus shape with a convex surface facing the object side, the second lens 120 has a meniscus shape with a convex surface facing the object side, and the third lens 130 has a flat surface with the convex surface facing the object side. The fourth lens 150 disposed on the image side of the aperture stop 140 has a biconvex shape with a convex surface facing the image side, and the fifth lens 160 has a meniscus shape with the convex surface facing the image side. The second lens 120 has an aspheric surface on both sides, the fourth lens 150 has an aspheric surface on one side, and the fifth lens 160 has an aspheric surface on one side.

Table 5 shows the stop corresponding to each surface number of the imaging lens 100B in Example 2, the radius of curvature R, the interval D, the refractive index Nd, and the Abbe number νd of each lens. In Table 5, the surface numbered with * indicates that the surface is aspherical. Table 6 shows the aspheric coefficient of the predetermined surface.
<Numerical Example 2>

図５は、実施例２において、図５（Ａ）が球面収差（左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm）を、図５（Ｂ）が非点収差（実線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのサジタル光線、点線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのタンジェンシャル光線）を、図５（Ｃ）が歪曲収差（435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmが重なっている）をそれぞれ示している。図５からわかるように、実施例２によれば、球面、歪曲、非点の諸収差が良好に補正され、結像性能に優れた撮像レンズ１００Ｂが得られる。

5A is a spherical aberration (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, 656.3 nm from the left) and FIG. 5B is an astigmatism (solid line: left) in Example 2. (5) to 435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm sagittal rays, dotted line: 435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm tangential rays from the left). Distortion aberrations (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, and 656.3 nm overlap) are shown. As can be seen from FIG. 5, according to the second embodiment, the spherical lens, distortion, and astigmatism aberrations are corrected favorably, and an imaging lens 100B having excellent imaging performance can be obtained.

  The basic configuration of the imaging lens 100C according to the third embodiment is shown in FIG. 6, each numerical data (setting value) is shown in Tables 7 and 8, and the aberration diagram showing spherical aberration, distortion, and astigmatism is shown in FIG. Respectively.

The imaging lens 100C according to the third embodiment is designed for the purpose of shortening the back focus and reducing the size of the second embodiment.
As shown in FIG. 6, the first lens 110 has a meniscus shape with a convex surface facing the object side, the second lens 120 has a meniscus shape with a convex surface facing the object side, and the third lens 130 has a flat surface with the convex surface facing the object side. The fourth lens 150 disposed on the image side of the aperture stop 140 has a biconvex shape with a convex surface facing the image side, and the fifth lens 160 has a meniscus shape with the convex surface facing the image side. The second lens 120 has an aspheric surface on both sides, the fourth lens 150 has an aspheric surface on one side, and the fifth lens 160 has an aspheric surface on one side.

Table 7 shows the stop corresponding to each surface number of the imaging lens 100C in Example 3, the radius of curvature R, the interval D, the refractive index Nd, and the Abbe number νd of each lens. In Table 7, the surface numbered with * indicates that the surface is aspherical. Table 8 shows the aspheric coefficient of the predetermined surface.
<Numerical Example 3>

図７は、実施例３おいて、図７（Ａ）が球面収差（左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm）を、図７（Ｂ）が非点収差（実線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのサジタル光線、点線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのタンジェンシャル光線）を、図７（Ｃ）が歪曲収差（435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmが重なっている）をそれぞれ示している。図７からわかるように、実施例３によれば、球面、歪曲、非点の諸収差が良好に補正され、結像性能に優れた撮像レンズ１００Ｃが得られる。

7A is a spherical aberration (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, 656.3 nm from the left), and FIG. 7B is an astigmatism (solid line: solid line: Example 3). Sagittal rays of 435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm from the left, dotted line: tangential rays of 435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm from the left), Fig. 7 (C) Shows distortion aberrations (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, and 656.3 nm overlapping), respectively. As can be seen from FIG. 7, according to the third embodiment, the spherical lens, distortion, and various astigmatism aberrations are corrected well, and the imaging lens 100C having excellent imaging performance can be obtained.

  The basic configuration of the imaging lens 100D according to the fourth embodiment is shown in FIG. 8. Each numerical data (setting value) is shown in Tables 9 and 10, and the aberration diagrams showing spherical aberration, distortion, and astigmatism are shown in FIG. Respectively.

The imaging lens 100D in Example 4 is designed when the ratio of the focal length f2 of the second lens and the focal length f4 of the fourth lens in Example 3 is 0.9: 1.0.
As shown in FIG. 8, the first lens 110 has a meniscus shape with a convex surface facing the object side, the second lens 120 has a meniscus shape with a convex surface facing the object side, and the third lens 130 has a flat surface with the convex surface facing the object side. The fourth lens 150 arranged on the image side of the aperture stop 140 has a biconvex shape with the convex surface facing the image side, and the fifth lens 160 has a biconvex shape with the convex surface facing the image side. The second lens 120 has an aspheric surface on both sides, the fourth lens 150 has an aspheric surface on one side, and the fifth lens 160 has an aspheric surface on one side.

Table 9 shows the stop corresponding to each surface number of the imaging lens 100D in Example 4, the radius of curvature R, the interval D, the refractive index Nd, and the Abbe number νd of each lens. In Table 9, the surface numbered with * indicates that the surface is aspherical. Table 10 shows the aspheric coefficient of the predetermined surface.
<Numerical Example 4>

図９は、実施例４おいて、図９（Ａ）が球面収差（左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm）を、図９（Ｂ）が非点収差（実線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのサジタル光線、点線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのタンジェンシャル光線）を、図９（Ｃ）が歪曲収差（435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmが重なっている）をそれぞれ示している。図９からわかるように、実施例４によれば、球面、歪曲、非点の諸収差が良好に補正され、結像性能に優れた撮像レンズ１００Ｄが得られる。

FIG. 9 shows the spherical aberration (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, 656.3 nm from the left) and FIG. 9B shows the astigmatism (solid line: solid line) in Example 4. Sagittal rays of 435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm from the left, dotted lines: 435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm tangential rays from the left), Fig. 9 (C) Shows distortion aberrations (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, and 656.3 nm overlapping), respectively. As can be seen from FIG. 9, according to the fourth embodiment, the spherical lens, distortion, and various astigmatism aberrations are corrected well, and the imaging lens 100D having excellent imaging performance can be obtained.

  The basic configuration of the imaging lens 100E according to Embodiment 5 is shown in FIG. 10, each numerical data (setting value) is shown in Tables 11 and 12, and the aberration diagram showing spherical aberration, distortion, and astigmatism is shown in FIG. Respectively.

  The imaging lens 100E in Example 5 is designed when the ratio of the focal length f2 of the second lens and the focal length f4 of the fourth lens in Example 3 is 1.1: 1.0.

  As shown in FIG. 10, the first lens 110 has a meniscus shape with a convex surface facing the object side, the second lens 120 has a meniscus shape with a convex surface facing the object side, and the third lens 130 has a flat surface with the convex surface facing the object side. The fourth lens 150 arranged on the image side of the aperture stop 140 has a biconvex shape with the convex surface facing the image side, and the fifth lens 160 has a biconvex shape with the convex surface facing the image side. The second lens 120 has an aspheric surface on both sides, the fourth lens 150 has an aspheric surface on one side, and the fifth lens 160 has an aspheric surface on one side.

Table 11 shows the stop corresponding to each surface number of the imaging lens 100E in Example 5, the radius of curvature R, the interval D, the refractive index Nd, and the Abbe number νd of each lens. In Table 11, a surface numbered with * indicates that it has an aspherical shape. Table 12 shows the aspheric coefficient of the predetermined surface.
<Numerical example 5>

図１１は、実施例５において、図１１（Ａ）が球面収差（左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm）を、図１１（Ｂ）が非点収差（実線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのサジタル光線、点線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのタンジェンシャル光線）を、図１１（Ｃ）が歪曲収差（435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmが重なっている）をそれぞれ示している。図１１からわかるように、実施例５によれば、球面、歪曲、非点の諸収差が良好に補正され、結像性能に優れた撮像レンズ１００Ｅが得られる。

11A is a spherical aberration (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, 656.3 nm from the left), and FIG. 11B is an astigmatism (solid line: left) in Example 5. 115.8C, 486.1nm, 546.1nm, 587.6nm, 656.3nm sagittal rays, dotted line: 435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm tangential rays from the left), Figure 11 (C) Distortion aberrations (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, and 656.3 nm overlap) are shown. As can be seen from FIG. 11, according to the fifth embodiment, the imaging lens 100 </ b> E excellent in imaging performance can be obtained in which various spherical, distortion, and astigmatism aberrations are satisfactorily corrected.

  The basic configuration of the imaging lens 100F according to the sixth embodiment is shown in FIG. 12, each numerical data (setting value) is shown in Table 13 and Table 14, and the aberration diagram showing spherical aberration, distortion, and astigmatism is shown in FIG. Respectively.

  The imaging lens 100F according to the sixth embodiment is designed to correct aberration when the total angle of view 2W of light incident on the horizontal image height position on the imaging plane is close to 180 °.

  As shown in FIG. 12, the first lens 110 has a meniscus shape with a convex surface facing the object side, the second lens 120 has a meniscus shape with a convex surface facing the object side, and the third lens 130 has a flat surface with the convex surface facing the object side. The fourth lens 150 disposed on the image side of the aperture stop 140 has a biconvex shape with a convex surface facing the image side, and the fifth lens 160 has a meniscus shape with the convex surface facing the image side. The second lens 120 has an aspheric surface on both sides, the fourth lens 150 has an aspheric surface on one side, and the fifth lens 160 has an aspheric surface on one side.

Table 13 shows the stop corresponding to each surface number of the imaging lens 100F in Example 6, the radius of curvature R, the interval D, the refractive index Nd, and the Abbe number νd of each lens. In Table 13, the surface with * in the surface number indicates an aspherical shape. Table 14 shows the aspheric coefficient of the predetermined surface.
<Numerical Example 6>

図１３は、実施例６において、図１３（Ａ）が球面収差（左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm）を、図１３（Ｂ）が非点収差（実線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのサジタル光線、点線：左から435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmのタンジェンシャル光線）を、図１３（Ｃ）が歪曲収差（435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nmが重なっている）をそれぞれ示している。図１３からわかるように、実施例６によれば、球面、歪曲、非点の諸収差が良好に補正され、結像性能に優れた撮像レンズ１００Ｆが得られる。

13A is a spherical aberration (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, 656.3 nm from the left) and FIG. 13B is an astigmatism (solid line: left) in Example 6. To 135.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm sagittal rays, dotted line: from the left 435.8nm, 486.1nm, 546.1nm, 587.6nm, 656.3nm tangential rays), Fig. 13 (C) Distortion aberrations (435.8 nm, 486.1 nm, 546.1 nm, 587.6 nm, and 656.3 nm overlap) are shown. As can be seen from FIG. 13, according to the sixth embodiment, the spherical lens, the distortion, and the various astigmatism aberrations are corrected well, and the imaging lens 100F having excellent imaging performance can be obtained.

  Further, according to the imaging lens of the present embodiment, it is suitable for a camera or the like equipped with an imaging device, and an imaging device including a wide-angle imaging lens having high optical performance while being small, light, and inexpensive can be realized.

  FIG. 14 shows a cross-sectional view of an embodiment of an imaging apparatus using the imaging lens 100 according to the present invention. The imaging lens 100 and the imaging element 210 such as a CCD (Charge Coupled Device) or a CMOS (Complementary Mental-Oxide Semiconductor device) are defined and held by a housing 220. At this time, the imaging surface 170 of the imaging lens 100 is disposed so as to coincide with the light receiving surface of the imaging element 210.

  The subject image captured by the imaging lens 100 and formed on the light receiving surface of the imaging element 210 is converted into an electrical signal by the photoelectric conversion function of the imaging element 210 and output from the imaging apparatus 200 as an image signal.

  The imaging lens 100 as described above is small, thin, lightweight, and can be compact in mounting space, and thus is suitable for imaging devices for various applications. In addition, although it is a wide-angle imaging lens, it can correct the occurrence of various aberrations well, form a subject image with high optical performance on the light receiving surface of the imaging device 210, and output an image signal with excellent visibility. Since it has high weather resistance that can cope with the heat generation of the electric system, it is possible to realize an imaging device that has a superior advantage particularly in surveillance cameras and in-vehicle cameras that require a sealed structure.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention.

100, 100A to 100F: imaging lens 110: first lens 120: second lens 130: third lens 140: aperture stop 150: fourth lens 160: fifth lens 170: image plane 200. ..Image sensor 220 ... casing

Claims (7)

In order from the object side, is formed by a glass material, a first lens having a negative refractive power, is formed of a resin material, and a second lens having a negative refractive power, it is formed of glass material, a positive refractive power A third lens having an aperture stop, a fourth lens made of a resin material and having a positive refractive power, and a fifth lens made of a glass material, and the focal length of the second lens is f2, When the focal length of the fourth lens is f4, the following conditional expression (1) is satisfied:
−1.1 <f2 / f4 <−0.9 (1) The imaging lens according to claim 1, wherein at least one lens surface of the second lens and the fourth lens has an aspherical shape.   The first lens has a convex surface facing the object side, the third lens has a convex surface facing the object side, and the fourth lens has a convex surface facing the image side. Imaging lens. The following conditional expression (2) is satisfied, where Bf is a distance from an image plane side surface of the fifth lens to an imaging plane, and f is a focal length of the entire imaging lens system. The imaging lens according to any one of 1 to 3 .
Bf / f ≧ 0.7 (2) The Abbe number for the d-line of the material constituting the first lens is 40 or more, the Abbe number for the d-line of the material constituting the second lens is 50 or more, and the d-line of the material constituting the third lens is the Abbe number of 40 or less, the fourth Abbe number at the d-line of the material of the lens is 50 or higher, the imaging lens according to any one of claims 1 to 4, characterized in that it is set respectively. The imaging lens according to any one of claims 1 to 5, characterized by satisfying the following conditional expression (3).
2W ≧ 180 ° (3)
However, 2W is the total angle of view of light rays incident on the horizontal image height position on the imaging plane. An imaging lens according to any one of claims 1 to 6, the imaging apparatus characterized by comprising an imaging device that converts an optical image into an electrical signal be imaged through the imaging lens.

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