JP6568905B2 - Lens and camera - Google Patents

Description

  The present invention relates to a lens and a camera.

  Development of a driving support system using an in-vehicle camera is in progress. As an example of a driving support system, Patent Literature 1 discloses a lane recognition device that detects a lane position from an image captured by a vehicle-mounted camera.

JP 2007-264714 A

  If a false resolution such as moire occurs in an image captured by an in-vehicle camera, the lane recognition device disclosed in Patent Document 1 may not be able to accurately detect the lane position. Even a driving support system that detects something other than the lane position may not operate normally if moire occurs in an image captured by the camera. Therefore, there is a demand for a lens and a camera that are less likely to cause false resolution such as moire in the captured image.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a lens and a camera with less occurrence of false resolution.

In order to achieve the above object, a lens according to the first aspect of the present invention is:
Arranged in order from the subject to the image sensor,
Have a positive refractive power, the second surface and the first lens element Ru plane der opposite the first surface facing the object is a convex said imaging device,
An aperture stop having an aperture;
Have a negative refractive power, said fourth surface opposite the third surface and the imaging element facing the object and a second lens element Ru concave der respectively,
Have a positive refractive power, said sixth surface opposite the fifth surface and the imaging element facing the object and a third lens element, respectively Ru convex der,
Have a positive refractive power, eighth surface opposite the seventh surface is convex the imaging element facing the object and a fourth lens element Ru concave der,
Have a negative refractive power, tenth surface and the fifth lens element Ru concave der opposite the ninth surface facing the object is a convex image pickup element, made of,
The absolute value of the first curvature radius of the first surface of the first lens element is 8.418965 (mm), the absolute value of the second curvature radius of the second surface is ∞,
The absolute value of the third curvature radius of the third surface of the second lens element is 4.1556 (mm), and the absolute value of the fourth curvature radius of the fourth surface is 5.8776304 (mm),
The absolute value of the fifth curvature radius of the fifth surface of the third lens element is 5.8776304 (mm), and the absolute value of the sixth curvature radius of the sixth surface is 3.9075 (mm),
The absolute value of the seventh curvature radius of the seventh surface of the fourth lens element is 4.6 (mm), and the absolute value of the eighth curvature radius of the eighth surface is 36 (mm);
The absolute value of the ninth curvature radius of the ninth surface of the fifth lens element is 51.51849 (mm), and the absolute value of the tenth curvature radius of the tenth surface is 5.7 (mm),
The radius of curvature R1 expressed by the absolute value of the sixth surface of the third lens element facing the image sensor and the focal length f of the entire lens system satisfy R1 / f ≦ 0.74.

  By doing so, the spherical aberration of the lens increases, and it is possible to suppress false resolution such as moire generated in the captured image.

A radius of curvature R2 expressed by an absolute value of the tenth surface of the fifth lens element facing the imaging element may satisfy R2 / f ≧ 0.81.
By doing so, irregular reflection due to the surface of the fifth lens element facing the imaging element is reduced, and ghost is less likely to occur in the captured image.

The fourth lens element and the fifth lens element are made of resin,
Both surfaces or one surface of the fourth lens element is composed of an aspheric surface,
Both surfaces or one surface of the fifth lens element may be aspherical.
In this way, a good image can be obtained with a small number of lenses.

The second lens element is bonded to the third lens element;
The third lens element may be made of glass having an Abbe number larger than that of the glass constituting the second lens element.
In this way, chromatic aberration can be corrected.

In order to achieve the above object, a camera according to a second aspect of the present invention provides:
The lens;
An image sensor in which a subject image is formed on an imaging surface by the lens;
Is provided.
In this way, a camera with less false resolution can be obtained.

  According to the present invention, spherical aberration of a lens is increased, and false resolution such as moire generated in a captured image can be suppressed. Therefore, it is possible to provide a lens and a camera with less occurrence of false resolution.

It is sectional drawing which shows the camera which concerns on embodiment of this invention. It is a figure which shows the spherical aberration of the lens which concerns on embodiment of this invention. It is a figure which shows MTF in the Nyquist frequency of the lens which concerns on embodiment of this invention. It is a figure which shows MTF in the half Nyquist frequency of the lens which concerns on embodiment of this invention. It is sectional drawing which shows the camera which concerns on a comparative example. It is a figure which shows the spherical aberration of the lens which concerns on a comparative example. It is a figure which shows MTF in the Nyquist frequency of the lens which concerns on a comparative example. It is a figure which shows MTF in the half Nyquist frequency of the lens which concerns on a comparative example.

  Hereinafter, a lens according to an embodiment for carrying out the present invention will be described in detail with reference to the drawings, taking as an example a lens provided in a vehicle-mounted camera.

  As shown in FIG. 1, a camera 100 according to an embodiment of the present invention includes a lens 110 including first to fifth lens elements 10 to 50, and an imaging element on which an object image is formed on an imaging surface by the lens 110. 120, a diaphragm 70, a lens 110, an image sensor 120, and a housing 130 that houses the diaphragm 70. The camera 100 is used as an in-vehicle camera. The image captured by the camera 100 is used in a driving support system that detects a lane position. The lens 110 has a focal length f of the entire lens system.

  The imaging element 120 converts the subject image formed on the imaging surface by the lens 110 into an electrical signal. The image sensor 120 is not particularly limited as long as it converts an object image into an electrical signal, and is configured by, for example, a CCD (Charge-Coupled Device) type image sensor, a CMOS (Complementary Metal Oxide Semiconductor) type image sensor, or the like. A flat glass filter 60 is disposed on the imaging surface of the imaging element 120. The glass filter 60 includes a low-pass filter, an infrared cut filter, and the like.

  In the housing 130, the first lens element 10, the diaphragm 70, the second lens element 20, the third lens element 30, the fourth lens element 40, and the fifth lens element 50 are sequentially arranged from the subject toward the image sensor 120. Has been placed.

  The first lens element 10 is made of glass and has a positive refractive power. The surface 11 of the first lens element 10 facing the subject is a convex surface, and the surface 12 facing the imaging element 120 is a flat surface. The surface 11 is formed as a spherical surface.

  The diaphragm 70 is made of a non-translucent resin having an opening 71 and is disposed between the first lens element 10 and the second lens element 20. The diaphragm 70 determines the F value of the lens 110. The F value is an index indicating the brightness of the lens.

  The second lens element 20 is made of glass and has negative refractive power. A surface 21 facing the subject of the second lens element 20 and a surface 22 facing the image sensor 120 are concave surfaces. The surface 21 and the surface 22 are formed as spherical surfaces.

  The third lens element 30 is made of glass and has a positive refractive power. The surface 31 facing the subject of the third lens element 30 and the surface 32 facing the imaging element 120 are convex surfaces. The surface 31 and the surface 32 are formed as spherical surfaces. The radius of curvature R1 of the surface 32 of the third lens element 30 satisfies R1 / f ≦ 0.74. Preferably, the radius of curvature R1 / f ≦ 0.70. The surface 31 of the third lens element 30 is bonded to the surface 22 of the second lens element 20. The third lens element 30 is made of glass having a smaller dispersion (a larger Abbe number) than the glass used for the second lens element 20 in order to correct chromatic aberration. The Abbe number vd3 of the third lens element is preferably 15 or more larger than the Abbe number vd2 of the second lens element.

  The fourth lens element 40 is a convex meniscus lens made of resin and having a positive refractive power. The surface 41 facing the subject of the fourth lens element 40 is a convex surface, and the surface 42 facing the image sensor 120 is a concave surface. The surface 41 and the surface 42 are formed as aspheric surfaces.

  The fifth lens element 50 is a concave meniscus lens made of resin and having negative refractive power. The surface 51 of the fifth lens element 50 facing the subject is a convex surface, and the surface 52 facing the imaging element 120 is a concave surface. The surface 51 and the surface 52 are formed as aspherical surfaces. The fifth lens element 50 has a negative refracting power while the fourth lens element 40 has a positive refracting power in order to cancel out of focus shift due to contraction and expansion due to a temperature change. The radius of curvature R2 of the surface 52 of the fifth lens element satisfies R2 / f ≧ 0.81.

  Next, an example in which a specific numerical example of the lens 110 having the above configuration is used in the camera 100 will be described below.

Object distance: ∞
Focal length f of the entire lens system: 5.6775 (mm)
F value: 2.5
Angle of view: 60 °
Back focus: 2.354 (mm)
Distance TL on the optical axis L from the surface 11 of the first lens element 10 to the imaging surface of the imaging device 120: 11.804 (mm)
Ray passage height of lens Surface 11 of first lens element 10: 2.838937 (mm)
Surface 12 of the first lens element 10: 2.122587 (mm)
Aperture 70: 2.122587 (mm)
Surface 21 of second lens element 20: 2.494089 (mm)
Surface 22 of the second lens element 20 and surface 31 of the third lens element 30: 3.280028 (mm)
Surface 32 of the third lens element 30: 5.094437 (mm)
Surface 41 of the fourth lens element 40: 5.557087 (mm)
Surface 42 of the fourth lens element 40: 5.402969 (mm)
Surface 51 of the fifth lens element 50: 5.555459 (mm)
Surface 52 of the fifth lens element 50: 5.333353 (mm)
Number of pixels per mm of the image sensor 120 of the camera 100: 238 pixels Vertical length of the imaging surface of the image sensor 120: 5.376 (mm), horizontal length: 3.024 (mm)

  The refractive index nd1 of the first lens element 10 is 2.000704, the Abbe number vd1 is 25.45838, the radius of curvature R11 of the surface 11 is 8.418965 (mm), the radius of curvature of the surface 12 is R12 = ∞, and the diameter is 3.223997. (Mm), the distance D1 of the surface 11 and the surface 12 on the optical axis L = 1.1 (mm)

  Diameter R71 of the opening 71 of the diaphragm 70 = 2.122875 (mm)

  Refractive index nd2 = 2.00704 of the second lens element 20, Abbe number vd2 = 2.4583838, radius of curvature R21 = 4.1556 (mm) of the surface 21, radius of curvature R22 = 5.876304 (mm) of the surface 22, Diameter = 5.094437, distance D2 on the optical axis L between the surface 12 and the surface 21 = 0.9 (mm), distance D3 on the optical axis L between the surface 21 and the surface 22 = 0.9 (mm)

  Refractive index nd3 = 1.83482 of the third lens element 30, Abbe number vd3 = 42.72179, radius of curvature R31 = 5.876304 (mm) of the surface 31, radius of curvature R1 = 3.99075 (mm) of the surface 32, Diameter = 5.384144 (mm), distance D4 on the optical axis L between the surface 31 and the surface 32 = 2.75 (mm), R1 / f = 0.68824

  The refractive index nd4 of the fourth lens element 40 is 1.525338, the Abbe number vd4 is 56.28929, the radius of curvature R41 of the surface 41 is 4.6 (mm) (aspherical surface), and the radius of curvature R42 of the surface 42 is 36 (mm). ) (Aspheric surface), diameter = 5.861712, distance D5 on the optical axis L between the surface 32 and the surface 41 = 0.2 (mm), distance D6 = 1 on the optical axis L between the surface 41 and the surface 42 .5 (mm)

  Refractive index nd5 = 1.63518 of the fifth lens element 50, Abbe number vd5 = 23.996382, radius of curvature R51 = 51.51849 (mm) (aspherical surface), radius of curvature R2 of the surface 52 = 5.7 (Mm) (aspherical surface), diameter = 5.878845 (mm), distance D7 on the optical axis L between the surface 42 and the surface 51 = 0.8 (mm), on the optical axis L between the surface 51 and the surface 52 Distance D8 = 1.3 (mm), R2 / f = 1.00

  Refractive index nd6 = 1.516798 of glass filter 70, Abbe number vd6 = 64.19826, radius of curvature R61 = ∞ of surface 61, radius of curvature R62 = ∞ of surface 62, on optical axis L between surfaces 52 and 61 The distance D9 = 2.045 (mm), the distance D10 on the optical axis L between the surface 61 and the surface 62 = 0.5 (mm)

Numerical data of aspheric coefficient Surface 41 of the fourth lens element 40:
ε = 1.0000000, D = −0.000640, E = 0, F = 0, G = 0
Surface 42 of the fourth lens element 40:
ε = 1.0000000, D = 0.469, E = 0, F = 0, G = 0
Surface 51 of the fifth lens element 50:
ε = 1.0000000, D = 0.005338, E = −0.00027, F = 8.71 × 10 ⁻⁶ , G = 0
Surface 52 of the fifth lens element 50:
ε = 1.0000000, D = 0.004944, E = −0.00047, F = 2.33 × 10 ⁻⁵ , G = 0

FIG. 2 shows the spherical aberration in the lens 110 of the above example. FIG. 3 shows the MTF (Modulation Transfer Function) of the lens 110 at the Nyquist frequency, and FIG. 4 shows the MTF at the half Nyquist frequency. If the pixel pitch is a, the Nyquist frequency is obtained by 1 / (a × 2). Since the number of pixels per 1 mm of the image sensor 120 is 238 pixels, the pixel pitch a is 1 mm / 238 = 0.0042 mm = 4.2 μm. The Nyquist frequency is 1 / (a × 2) = 119 mm ⁻¹ . The half Nyquist frequency is half the value of the Nyquist frequency and is 59.5 mm ⁻¹ . Spherical aberration is shown for each of light having wavelengths of 436 nm, 588 nm, 546 nm, 486 nm, and 656 nm. The spherical aberration of the lens 110 is distributed between −0.06 and 0.06, and it is shown that the spherical aberration is larger than the comparative example described later. The MTF expresses how faithfully the contrast of the subject can be reproduced in order to know the imaging performance of the lens 110 as a spatial frequency characteristic. If the maximum value of MTF exceeds 0.4 at the Nyquist frequency, it may cause false resolution such as moire. However, even if the MTF value at the half Nyquist frequency is large, it may cause false resolution such as moire. It is hard to become. Since the spherical aberration of the lens 110 is large, in the lens 110 of the example, the maximum value of the MTF at the Nyquist frequency is 0.4. At the half Nyquist frequency, the MTF exceeds 0.6, indicating that the imaging performance is maintained.

Next, the spherical aberration on each surface in the lens 110 of the example is shown below.
The spherical aberration due to the surface 11 of the first lens element 10 is 0.000697, and the spherical aberration due to the surface 12 is 0.001956. The spherical aberration due to the surface 21 of the second lens element 20 is −0.019333, and the spherical aberration due to the surface 22 is −0.002226. The spherical aberration due to the surface 31 of the third lens element 30 is −0.002226, and the spherical aberration due to the surface 32 is 0.034403. The spherical aberration of the surface 41 of the fourth lens element 40 is −0.004751 and the spherical aberration of the surface 42 is −0.006053. The spherical aberration of the surface 51 of the fifth lens element 50 is 0.000394, and the spherical aberration of the surface 52 is -0.000133. Here, the spherical aberration is caused by light having a wavelength of 0.5876. From the above, it can be seen that the spherical aberration due to the surface 32 of the third lens element is the largest in the lens 110 of the example. This is considered because the radius of curvature R1 of the surface 32 satisfies R1 / f = 0.68824 ≦ 0.74. Therefore, it is considered that the large spherical aberration due to the surface 32 contributes to the large spherical aberration in the entire lens 110.

  As described above, according to the lens 110 of the present embodiment, when the curvature radius R1 of the surface 32 of the third lens element 30 satisfies R1 / f ≦ 0.74, the spherical aberration due to the entire lens system is increased. The MTF value exceeds 0.6 at the half Nyquist frequency while the MTF value is 0.4 or less at the Nyquist frequency. In the lens 110, the MTF value exceeds 0.6 at the half Nyquist frequency, and the imaging performance is maintained. In addition, since the MTF value can be 0.4 or less at the Nyquist frequency, the camera 100 including the lens 110 can capture an image with less occurrence of false resolution such as moire. The third lens element 30 having a positive refractive power is made of glass having an Abbe number larger than that of the glass used for the second lens element 20 having a negative refractive power. Thereby, chromatic aberration (axial chromatic aberration and lateral chromatic aberration) can be corrected. Further, since the fourth lens element 40 and the fifth lens element 50 are made of resin aspheric lenses, the size of the lens 110 can be reduced, and the lens 110 can be produced at low cost. Further, the fourth lens element 40 has a positive refractive power, and the fifth lens element 50 has a negative refractive power, so that the focus shift due to contraction and expansion is canceled by a temperature change. Thereby, the focus shift due to the temperature change can be reduced. Moreover, generation | occurrence | production of a ghost can be prevented because the curvature radius R2 of the surface 52 of the 5th lens element 50 satisfy | fills R2 / f = 1.00> = 0.81. Accordingly, it is possible to provide the lens 110 and the camera 100 with less false resolution. Therefore, even if the image captured by the camera 100 is used in a driving support system or the like, it is difficult to adversely affect the recognition of the driving support system.

  Next, a comparative example in which the radius of curvature R1 of the surface 32 of the third lens element 30 does not satisfy R1 / f ≦ 0.74 will be described. As shown in FIG. 5, the lens 110 ′ according to the comparative example includes first to fifth lens elements 10 ′ to 50 ′. Specific numerical values of the lens 110 'are shown below. The surface 11 'and the surface 12' are convex surfaces. Surface 21 'and surface 22' are concave. The surface 31 'and the surface 32' are convex surfaces. The surface 41 'and the surface 42' are convex surfaces. The surface 51 'and the surface 52' are concave surfaces.

Focal length f ′ of the entire lens system = 5.6679 (mm)
Back focus = 2.513 (mm)
Ray passage height of lens Surface 11 ′ of first lens element 10 ′: 3.64 (mm)
Surface 12 ′ of the first lens element 10 ′: 2.89 (mm)
Aperture 70: 2.28 (mm)
Surface 21 ′ of the second lens element 20 ′: 2.80 (mm)
Surface 22 ′ of the second lens element 20 ′ and surface 31 ′ of the third lens element 30 ′: 5.06 (mm)
Surface 32 ′ of the third lens element 30 ′: 5.06 (mm)
Surface 41 ′ of the fourth lens element 40 ′: 5.86 (mm)
Surface 42 ′ of the fourth lens element 40 ′: 5.56 (mm)
Surface 51 ′ of the fifth lens element 50 ′: 5.56 (mm)
Surface 52 ′ of the fifth lens element 50 ′: 5.53 (mm)
The distance TL ′ on the optical axis L from the surface 11 ′ of the first lens element 10 ′ to the imaging surface of the imaging element 120 is 12.143 (mm).

  The curvature radius R11 ′ of the first lens element 10 ′ surface 11 ′ = 8.7773973 (mm), the curvature radius R12 ′ = 21.8172 of the surface 12 ′, diameter = 3.639264 (mm), the surfaces 11 ′ and 12 Distance D1 on the optical axis L with respect to '= 1.2 (mm)

  The radius of curvature R21 ′ of the surface 21 ′ of the second lens element 20 ′ = 4.991556 (mm), the radius of curvature R22 ′ of the surface 22 ′ = 4.163448 (mm), the diameter = 5.064, the surface 12 ′ and the surface The distance D2 ′ = 0.16 (mm) on the optical axis L from 21 ′, and the distance D3 ′ = 0.47 (mm) on the optical axis L between the surface 21 ′ and the surface 22 ′.

  The radius of curvature R31 ′ of the surface 31 ′ of the third lens element 30 ′ = 4.163448 (mm), the radius of curvature R1 ′ of the surface 32 ′ = 4.492221 (mm), the diameter = 5.064 (mm), the surface 31 Distance D4 'on the optical axis L between' and the surface 32 '= 4.53 (mm), R1' / f '= 0.79123

  The radius of curvature R41 ′ of the surface 41 ′ of the fourth lens element 40 ′ = 4.548263 (mm) (aspherical surface), the radius of curvature R42 ′ of the surface 42 ′ = 29.4906 (mm) (aspherical surface), diameter = 5 856791, the distance D5 ′ on the optical axis L between the surface 32 ′ and the surface 41 ′ = 0.1 (mm), the distance D6 ′ on the optical axis L between the surface 41 ′ and the surface 42 ′ = 1.4 ( mm)

  The radius of curvature R51 ′ of the surface 51 ′ of the fifth lens element 50 ′ = 13.66791 (mm) (aspherical surface), the radius of curvature R2 ′ of the surface 52 ′ = 5.211373 (mm) (aspherical surface), diameter = 5 562205 (mm), the distance D7 ′ on the optical axis L between the surface 42 ′ and the surface 51 ′ = 0.8 (mm), and the distance D8 ′ = 0 on the optical axis L between the surface 51 ′ and the surface 52 ′ = 0. .52 (mm)

  The radius of curvature R61 = ∞ of the surface 61 of the glass filter 60, the radius of curvature R62 = ∞ of the surface 62, the distance D9 ′ = 2.193 (mm) on the optical axis L between the surface 52 and the surface 61, and the surface 61 and the surface 62. Distance D10 ′ = 0.4 (mm) on the optical axis L

Numerical data of aspheric coefficient Surface 41 ′ of the fourth lens element 40 ′:
ε = 1.0000000, D = −0.00057, E = 5.04 × 10 ⁻⁵ , F = 4.03 × 10 ⁻⁵ , G = 0
Surface 42 'of the fourth lens element 40':
ε = 1.0000000, D = 0.0005623, E = −0.0001, F = 7.95 × 10 ⁻⁵ , G = 0
Surface 51 ′ of the fifth lens element 50 ′:
ε = 1.0000000, D = 0.420226, E = −0.00034, F = 2.86 × 10 ⁻⁵ , G = 0
Surface 52 ′ of the fifth lens element 50 ′:
ε = 1.0000000, D = −0.00125, E = −0.00059, F = 6.25 × 10 ⁻⁵ , G = 0

  In the comparative example, the object distance, the F value, the angle of view, the diameter R71 of the opening 71 of the diaphragm 70, and the refractive indexes and Abbe numbers of the first to fifth lens elements 10 ′ to 50 ′ are as in the example. This is the same as the lens 110 of FIG. The number of pixels per 1 mm of the image sensor 120 of the camera 100 ′ of the comparative example is the same as the number of pixels per mm of the image sensor of the camera 100 of the example.

  FIG. 6 shows spherical aberration in the lens 110 ′ of the comparative example. FIG. 7 shows the MTF at the Nyquist frequency, and FIG. 8 shows the MTF at the half Nyquist frequency. The radius of curvature R1 'of the surface 32' of the lens 110 'of the comparative example is 4.44921 mm. For this reason, R1 ′ / f ′ = 0.79123 and R1 ′ / f ′ ≦ 0.74 is not satisfied. The spherical aberration of the lens 110 'of the comparative example is distributed between -0.005 and 0.04, indicating that the spherical aberration is small. The maximum value of MTF at the Nyquist frequency of the lens 110 ′ of the comparative example is 0.6. The maximum value of MTF at the half Nyquist frequency is approximately 0.8. When this lens 110 ′ is used in the camera 100 ′, the maximum value of MTF exceeds 0.4 at the Nyquist frequency, so there is a possibility that false resolution occurs.

(Modification)
In the above-described embodiment, the lens 110 has a spherical lens in which the first to third lens elements 10 to 30 are made of glass, and the fourth and fifth lens elements 40 and 50 are made of resin. An example having a spherical lens has been described. The surface of the lens used in the first to fifth lens elements included in the lens 110 may be formed as a spherical surface, a flat surface, or an aspheric surface. In addition, the fourth and fifth lens elements 40 and 50 may be composed of aspherical lenses on one side. When the lens surface is a spherical surface or a flat surface, processing and assembly adjustment of the lens becomes easy, and optical performance deterioration due to errors in processing and assembly adjustment can be prevented. When the lens surface is aspherical, any of aspherical surfaces by grinding, a mold aspherical surface formed of glass or resin with a mold in an aspherical shape, or a composite aspherical surface formed with resin aspherical on the glass surface An aspherical surface may be used. If necessary, the lens surface may be a diffractive surface, and the lens may be a gradient index lens. Further, in the entire lens system, the surface exposed to the outside during use or the like can be subjected to various processing as required. As an example of this processing, the surface portion may be hydrophilized with a photocatalyst or the like in order to prevent the lens body from fogging or water droplet formation. Each of the first to fifth lens elements 10 to 50 may be composed of one lens, or a plurality of lenses may be combined into one lens element.

  In the above-described embodiment, the example in which the second lens element 20 and the third lens element 30 included in the lens 110 are cemented lenses has been described. The second lens element 20 and the third lens element 30 may be spaced apart. In the above-described embodiment, the example in which the second lens element 20 and the third lens element 30 correct chromatic aberration has been described. However, the correction of chromatic aberration is not performed by the second lens element 20 and the third lens element 30. Alternatively, the chromatic aberration may be corrected with a combination of lenses other than the combination of the second lens element 20 and the third lens element 30.

  In the above-described embodiment, the example in which the lens 110 has the diaphragm 70 has been described. The lens 110 may have a sub diaphragm between the third lens element 30 and the fourth lens element 40 in addition to the diaphragm 70. Thereby, coma aberration can be reduced.

  In the above-described embodiment, the example in which the camera 100 is used as an in-vehicle camera has been described. The camera 100 is not limited to a thing used as a vehicle-mounted camera, and may be used for a consumer camera such as a digital camera, a surveillance camera, a robot camera mounted on a robot, and the like.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention and do not limit the scope of the present invention.

  The present invention can be suitably used as an in-vehicle camera.

10, 10 'first lens elements 11, 11', 12, 12 'surfaces 20, 20' second lens elements 21, 21 ', 22, 22' surfaces 30, 30 'third lens elements 31, 31', 32 , 32 ′ surface 40, 40 ′ fourth lens element 41, 41 ′, 42, 42 ′ surface 50, 50 ′ fifth lens element 51, 51 ′, 52, 52 ′ surface 60, 60 ′ glass filter 70 aperture 71 aperture Part 100, 100 'camera 110, 110' lens 120 image sensor 130 housing f focal length

Claims (5)

Arranged in order from the subject to the image sensor,
Have a positive refractive power, the second surface and the first lens element Ru plane der opposite the first surface facing the object is a convex said imaging device,
An aperture stop having an aperture;
Have a negative refractive power, said fourth surface opposite the third surface and the imaging element facing the object and a second lens element Ru concave der respectively,
Have a positive refractive power, said sixth surface opposite the fifth surface and the imaging element facing the object and a third lens element, respectively Ru convex der,
Have a positive refractive power, eighth surface opposite the seventh surface is convex the imaging element facing the object and a fourth lens element Ru concave der,
Have a negative refractive power, tenth surface and the fifth lens element Ru concave der opposite the ninth surface facing the object is a convex image pickup element, made of,
The absolute value of the first curvature radius of the first surface of the first lens element is 8.418965 (mm), the absolute value of the second curvature radius of the second surface is ∞,
The absolute value of the third curvature radius of the third surface of the second lens element is 4.1556 (mm), and the absolute value of the fourth curvature radius of the fourth surface is 5.8776304 (mm),
The absolute value of the fifth curvature radius of the fifth surface of the third lens element is 5.8776304 (mm), and the absolute value of the sixth curvature radius of the sixth surface is 3.9075 (mm),
The absolute value of the seventh curvature radius of the seventh surface of the fourth lens element is 4.6 (mm), and the absolute value of the eighth curvature radius of the eighth surface is 36 (mm);
The absolute value of the ninth curvature radius of the ninth surface of the fifth lens element is 51.51849 (mm), and the absolute value of the tenth curvature radius of the tenth surface is 5.7 (mm),
The radius of curvature R1 expressed by the absolute value of the sixth surface of the third lens element facing the image sensor and the focal length f of the entire lens system satisfy R1 / f ≦ 0.74.
lens. A radius of curvature R2 expressed by an absolute value of the tenth surface of the fifth lens element facing the imaging element satisfies R2 / f ≧ 0.81.
The lens according to claim 1. The fourth lens element and the fifth lens element are made of resin,
Both surfaces or one surface of the fourth lens element is composed of an aspheric surface,
Both surfaces or one surface of the fifth lens element is composed of an aspheric surface.
The lens according to claim 1 or 2. The second lens element is bonded to the third lens element;
The third lens element is made of glass having an Abbe number larger than that of the glass constituting the second lens element.
The lens according to any one of claims 1 to 3. The lens according to any one of claims 1 to 4,
An image sensor in which a subject image is formed on an imaging surface by the lens;
With a camera.

Images