JP2019095657A - Imaging lens and imaging device - Google Patents

Abstract

To provide an imaging lens and imaging device that can improve both a speed and a resolution performance of a lens.SOLUTION: An imaging lens comprises, in order from an object side: a first lens 111 with negative power; a second lens 112 with positive power; a third lens 113 with the positive power; a fourth lens 114 with the negative power; a fifth lens 115 with the negative power; a sixth lens 116 with the positive power; and a seventh lens 117 with the positive power. Let a radius of curvature on an object side of the first lens be R1, a radius of curvature on an object side of the third lens be R6, a radius of curvature on an object side of the fourth lens be R8, a radius of curvature on an object side of the fifth lens be R9, a radius of curvature on an object side of the sixth lens be R11, and a focal length of an entire system be f, conditional expressions (1) to (5) are satisfied. (1)-7.89<R1/f<-7.27, (2)3.43<R6/f<3.60,(3)-2.16<R8/f<-2.09, (4)-1.34<R9/f<-1.30 and (5)-3.07<R11/f<-2.94.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a photographing lens and an imaging device.

  Lenses used for in-vehicle cameras, surveillance cameras and the like require a large angle of view, and are required to be bright lenses in consideration of outdoor use. In order to be a bright lens, it is necessary to reduce the f-number, but decreasing the f-number reduces the image quality. Therefore, a bright lens with good image quality is required. In order to achieve this demand, for example, as shown in Patent Document 1, combining a plurality of aspheric lenses or cemented lenses is applied.

JP, 2010-243711, A

  When a plurality of aspheric lenses are used as in the lens described in Patent Document 1, the design is time-consuming and expensive. Further, with the lens described in Patent Document 1, there is a limit to improving the brightness and resolution performance of the lens.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a photographing lens and an imaging device capable of improving both the brightness and the resolution performance of the lens.

In order to achieve the above object, a photographing lens according to the present invention is
From the object side,
A first lens having a negative power,
A second lens having a positive power,
A third lens having a positive power,
A fourth lens having a negative power,
A fifth lens having a negative power,
A sixth lens having a positive power,
And a seventh lens having a positive power,
The radius of curvature of the first lens on the object side is R1, the radius of curvature on the object side of the third lens is R6, the radius of curvature on the image plane side of the fourth lens is R8, and the object of the fifth lens Assuming that the curvature radius of the side is R9, the curvature radius of the image surface side of the sixth lens is R11, and the focal length of the entire system is f,
An imaging lens satisfying the following conditional expressions (1) to (5).
(1) -7.89 <R1 / f <-7.27
(2) 3.43 <R6 / f <3.60
(3) -2.16 <R8 / f <-2.09
(4) -1.34 <R9 / f <-1.30
(5)-3.07 <R11 / f <-2.94

  The third lens and the fourth lens are cemented to form a first cemented lens having positive power, and the fifth lens and the sixth lens are cemented, A second cemented lens having negative power may be formed.

  The object-side surface of the first lens may be concave.

  The seventh lens may be an aspheric lens.

  Even though the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are glass lenses Good.

  An imaging device according to the present invention includes the above-described imaging lens, and an imaging element that converts light transmitted through the imaging lens into an electrical signal.

  According to the present invention, it is possible to provide a photographing lens and an imaging device capable of improving both the brightness and the resolution performance of the lens.

FIG. 1 is a diagram showing a configuration of a photographing lens according to Embodiment 1. It is a figure which shows the aberration of the imaging lens which concerns on Example 1, (a) is spherical aberration, (b) shows a coma aberration. It is a figure which shows the aberration of the imaging lens which concerns on Example 1, (a) is a curvature of field, (b) shows a distortion aberration, (c) shows a magnification chromatic aberration. FIG. 6 is a graph showing MTF-image height characteristics of the photographing lens according to Example 1. FIG. 7 is a diagram showing a configuration of a photographing lens according to Embodiment 2. It is a figure which shows the aberration of the imaging lens which concerns on Example 2, (a) is spherical aberration, (b) shows a coma aberration. It is a figure which shows the aberration of the imaging lens which concerns on Example 2, (a) is a curvature of field, (b) shows a distortion aberration, (c) shows a magnification chromatic aberration. FIG. 7 is a view showing MTF-image height characteristics of the photographing lens according to Example 2; FIG. 7 is a diagram showing a configuration of a photographing lens according to Embodiment 3. It is a figure which shows the aberration of the imaging lens which concerns on Example 3, (a) is spherical aberration, (b) shows a coma aberration. It is a figure which shows the aberration of the imaging lens which concerns on Example 3, (a) is a curvature of field, (b) shows a distortion aberration, (c) shows a magnification chromatic aberration. FIG. 18 is a graph showing MTF-image height characteristics of the photographing lens according to Example 3. It is a figure which shows the MTF-image height characteristic of the imaging lens which concerns on the comparative example 1. FIG. It is a figure which shows the MTF-image height characteristic of the imaging lens which concerns on the comparative example 2. FIG.

  Hereinafter, a photographing lens according to an example of an embodiment of the present invention will be described with reference to the drawings.

Embodiment 1
The imaging lens according to the present embodiment is a lens incorporated in an imaging device, and an imaging device 100 is shown in FIG. The imaging apparatus 100 is a unit that outputs data indicating an image of an object when the user photographs the object, and includes a photographing lens 110 for forming an image of the object on the image plane P.

  As shown in FIG. 1, the imaging device 100 is an image sensor such as an infrared cut filter, an optical filter 120 such as a low pass filter, and a CCD (Charge Coupled Device) image sensor along the optical axis L and behind the imaging lens 110. And 130.

  The imaging device 100 further includes a frame (not shown) that fixes components such as the imaging lens 110, the optical filter 120, and the imaging device 130, and is mounted on optical devices such as an on-vehicle camera and a surveillance camera. The image plane P is formed on the object-side surface of the imaging element 130.

  According to such an imaging device 100, the image of the object is formed on the image plane P through the photographing lens 110, and the image data indicating the image of the object is generated by the imaging element 130 and output.

  The photographing lens 110 includes, in order from the object side, a first lens 111 having negative power, a second lens 112 having positive power, a third lens 113 having positive power, and negative power. And a fifth lens 115 having negative power, a sixth lens 116 having positive power, and a seventh lens 117 having positive power. An aperture stop 101 is disposed between the second lens 112 and the third lens 113, and a sub-aperture 102 is disposed between the sixth lens 116 and the seventh lens 117.

  In the following description, the first lens 111, the second lens 112, the aperture stop 101, the third lens 113, the fourth lens 114, the fifth lens 115, the sixth lens 116, the sub diaphragm 102, the fourth lens In the configuration in which the lens 117, the optical filter 120, and the image plane P are disposed from the object side to the image plane side along the optical axis L, as shown in FIG. The radius of curvature of each surface is represented by Ri (i = 1 to 15). Moreover, the term of the 1st surface-15th surface is used suitably as a name of S1-S15.

  The first lens 111 is a lens having negative power, in which the surface S1 on the object side and the surface S2 on the image surface side are concave, and is a spherical lens. In the present embodiment, by making the surface S1 on the object side concave, it is possible to provide a bright lens up to the peripheral portion of the image.

  The second lens 112 is a meniscus lens in which the surface S3 on the object side is convex and the surface S4 on the image plane is concave, and has a positive power. The surface S3 and the surface S4 are both spherical.

  The third lens 113 is a double-sided convex lens in which the surface S6 on the object side and the surface S7 on the image surface side are convex, and has positive power. The surface S6 and the surface S7 are both spherical.

  The fourth lens 114 is a meniscus lens having a concave surface S7 on the object side and a convex surface S8 on the image plane side, and has negative power. The surface S6 and the surface S7 are both spherical.

  The third lens 113 and the fourth lens 114 form a first cemented lens 118 in which an adhesive is applied to the opposing surfaces to bond them. The combination of the third lens 113 which is a convex lens and the fourth lens 114 which is a concave lens cancels the refraction by positive and negative powers and corrects the chromatic aberration and the spherical aberration. In addition, color shift is achieved by using crown-based glass, which is low dispersion optical glass, for the third lens 113, which is a convex lens, and flint-based glass, which is high dispersion optical glass, for the fourth lens 114 that is a concave lens. Gives the effect of achromatizing to cancel.

  The fifth lens 115 is a double-sided concave lens in which the surface S9 on the object side and the surface S10 on the image surface side are concave, and has negative power. The surface S9 and the surface S10 are both spherical.

  The sixth lens 116 is a double-sided convex lens in which the surface S10 on the object side has a convex surface and the surface S11 on the image surface side has a convex surface, and has positive power. The surface S10 and the surface S11 are both spherical. The fifth lens 115 and the sixth lens 116 form a second cemented lens 119 in which an adhesive is applied to the opposing surfaces to bond them. Similar to the first cemented lens 118, chromatic aberration and spherical aberration are corrected.

  The seventh lens 117 is a double-sided convex lens in which the surface S12 on the object side and the surface S13 on the image surface side are convex, and has positive power. The surface S12 and the surface S13 are aspheric surfaces. Aspheric lenses are produced, for example, by glass molding, in which the core of optical glass is heated at high temperature and pressed in the aspheric direction. By using an aspheric lens, distortion can be corrected, and the size of the entire lens system can be reduced without using an additional lens.

  The first lens 111 to the seventh lens 117 are arranged in the order of negative, positive, positive, negative, negative, positive and positive. The negative power generated by the first lens 111 is corrected with the positive power of the second lens 112 and the third lens 113. In addition, the first cemented lens 118 is formed of the third lens 113 of positive power and the fourth lens 114 of negative power, and the fifth lens 115 of negative power and the sixth lens of positive power The second cemented lens 119 is configured at 116. The chromatic aberration and the spherical aberration are mainly corrected by using positive and negative lenses, respectively. Finally, a seventh lens 117 for generating convex power is disposed to achieve an overall balanced arrangement.

  The aperture stop 101 is disposed between the second lens 112 and the third lens 113, and includes a surface S5. A sub diaphragm 102 is disposed between the sixth lens 116 and the seventh lens 117 to cut unnecessary light. By arranging the sub-aperture 102 at this position, coma and curvature of field are corrected.

  The optical filter 120 is an IR (Infra) cut filter, and is a filter that does not transmit infrared light by reflecting or absorbing incident infrared light. The IR filter is disposed on the back of the seventh lens 117.

The imaging lens 110 of the present embodiment is a lens that satisfies the following conditional expression.
The object side curvature radius of the first lens 111 is R1, the curvature radius of the third lens 113 object side is R6, the curvature radius of the fourth lens 114 side is R8, the object of the fifth lens 115 Assuming that the curvature radius of the side is R9, the curvature radius of the image surface side of the sixth lens 116 is R11, and the focal length of the entire system is f,
(1) -7.89 <R1 / f <-7.27
(2) 3.43 <R6 / f <3.60
(3) -2.16 <R8 / f <-2.09
(4) -1.34 <R9 / f <-1.30
(5)-3.07 <R11 / f <-2.94
The conditional expression

  According to the conditional expression (1), it is possible to shift the position of the principal point backward, to provide an imaging device having a long lens back necessary for a wide-angle lens, and to provide a lens bright to the periphery of an image. If the upper limit value of the conditional expression (1) is exceeded, the curvature of the first surface (S1) becomes large and the negative power becomes too large, and spherical aberration and distortion can not be corrected. If the lower limit value is exceeded, sufficient brightness can not be ensured.

  According to the conditional expression (2), chromatic aberration, spherical aberration and coma can be corrected effectively. If the upper limit value of conditional expression (2) is exceeded, aberration correction becomes difficult. If the lower limit value is exceeded, the positive power becomes too large, the angle of view of the wide-angle lens can be secured, and the occurrence of curvature of field becomes large.

According to the conditional expression (3), chromatic aberration, spherical aberration and coma aberration can be effectively corrected.
If the upper limit value of the conditional expression (3) is exceeded, the positive power is weak, and the positive power as the cemented lens can not be secured. If the lower limit value is exceeded, the aberration can not be corrected effectively.

According to the conditional expression (4), chromatic aberration, spherical aberration and coma aberration can be effectively corrected.
If the upper limit value of the conditional expression (4) is exceeded, aberration correction becomes difficult and the angle of view of the wide-angle lens can not be secured. When the lower limit is exceeded, the negative power becomes too large, the total power value of the first cemented lens becomes negative, and the negative power generated by the first lens 111 is gradually corrected to a positive power. It will be difficult to do.

According to the conditional expression (5), chromatic aberration, spherical aberration and coma can be corrected effectively.
If the upper limit value of the conditional expression (5) is exceeded, the negative power becomes large, and it becomes difficult to correct the aberration by suppressing the negative power of the first lens 111. Further, as the second cemented lens 119, positive power can not be generated. If the lower limit is exceeded, the positive power becomes large and the angle of view of the wide-angle lens can not be secured.

  The photographing lens 110 according to the present embodiment is a lens adopting an orthogonal projection method. The orthographic lens has a relationship of y = f · sin θ. Since the brightness is uniform at the center and periphery of the photographed image, the peripheral light amount does not decrease, and a bright lens can be provided.

  In addition, an image captured by a lens adopting the orthographic projection method is an image in which the central portion is greatly enlarged. Therefore, for example, when the imaging lens 110 of the present embodiment is employed as an on-vehicle lens, the detection capability of the image sensor near the central portion can be improved, and a long distance in car navigation can be achieved. Can improve the visual ability of

  The first lens 111 to the seventh lens 117 are all made of glass. Therefore, the durability is also excellent without affecting the refractive index due to the temperature change. In particular, it is suitable for a lens of an on-vehicle camera used outdoors and a lens of a surveillance camera.

Example 1
Surface data, aspheric surface data, various data, and power values of the photographing lens 110 in Example 1, which is a numerical value example corresponding to the present embodiment, are shown below.

(Plane data)
Unit mm
Face number r d nd vd
Object ∞ ∞
1 -40.401 1.20 1.80399 46.53
2 5.043 2.970
3 14.094 1.623 2.00272 19.32
4 114.096 1.811
5 (aperture) ∞ 0.065
6 18.850 2.819 1.83481 42.74
7-5.740 0.500 1. 76182 26.52
8 -11.369 1.765
9-7.044 0.700 1.92286 18.90
10 16.081 2.496 1.82080 32.32
11-16.081 0.200
12 * 16.406 2.496 1.82080 42.71
13 *-16.873 0.600
14 (filter) 0.8 0.8 15.1680 64.20
15 ∞ 6.756
Image plane ∞

  In the surface data, the lens surface of the surface number indicated with “* (asterisk)” is aspheric. A twelfth surface (S12) which is a surface on the object side of the seventh lens 117 of the photographing lens 110 and a thirteenth surface (S13) which is a surface on the image side are aspheric.

The characteristics of the aspheric lens are shown by the following equation.
^{Z = Cy 2 / [1+ (} 1- (1 + KC 2 y 2) 1/2] + A4y 4 + A6y 6 + A8y 6 + A10y 10
Here, Z is the sag amount (the amount in the direction parallel to the optical axis of the lens), y is the distance from the optical axis (radial direction), C is the curvature (1 / R) at the apex of the aspheric surface, and k is the cone constant , A4, A6, A8 and A10 represent fourth-order, sixth-order, eighth-order and tenth-order aspheric coefficients.

(Aspheric surface data)
The aspheric surface data of the 12th surface and the 13th surface are as follows.
12th
K = -0.030128858, A4 = 1.15309E-04, A6 = 3.45231E-06, A8 = -9.45677E-09, A10 = -7.61025E-10
13th surface
K = 0.11071436, A4 = 5.51429-E04, A6 = -7.39657E-07, A8 = 2.90565 E-07, A10 = -9.93471 E-09, A12 = 8.78794 E-11

(Various data)
F number = 1.6, maximum height increase = 4.32 mm, half angle of view (ω) = 52 °, total focal length = 5.351 mm, back focus (BF) = 8.16 mm, total lens length (TL) = 26.66 mm, diameter of aperture stop = 5.9 mm

(Power value)
The first lens 111 = −0.181, the second lens 112 = 0.063, the third lens 113 = 0.056, the fourth lens 114 = 0.079, the first cemented lens 118 = 0. 12, the fifth lens 115 = -0.129, the sixth lens 116 = 0.061, the second cemented lens 119 =-0.058, the seventh lens 117 = 0.095

  Values of conditional expressions (1) to (5) of the photographing lens 110 are conditional expression (1) = − 7.55, conditional expression (2) = 3.52, conditional expression (3) = − 2.12, conditions Expression (4) = − 1.32, conditional expression (5) = 3.01, and conditional expressions (1) to (5) are satisfied.

  The imaging lens 110 satisfying the conditional expressions (1) to (5) can suppress spherical aberration, coma aberration, curvature of field, and lateral chromatic aberration.

  2 (a) shows spherical aberration, FIG. 2 (b) shows coma aberration, FIG. 3 (a) shows curvature of field, and FIG. 3 (b) shows distortion. (C) is a graph showing magnification chromatic aberration, and FIG. 4 is a graph showing MTF characteristics of the photographing lens.

  In the graph showing the spherical aberration in FIG. 2A, the horizontal axis represents spherical aberration [mm], and the vertical axis represents the incident height of a light beam incident on the photographing lens 110. A solid line indicates g line, a two-dot broken line indicates c line, a long broken line indicates d line, a short broken line indicates F line, and a one-dot broken line indicates e line. The notation of the graph is the same as in FIGS. 2 (b) and 3 (c). The g-line indicates a wavelength of 0.436 μm, the F-line indicates 0.486 μm, the e-line indicates 0.546 μm, the d-line indicates 0.588 μm, and the c-line indicates a wavelength of 0.656 μm. At all wavelengths, it is 0.04 mm or less, and spherical aberration is well corrected.

  The flag indicating the coma aberration in FIG. 2B has an angle of view of 0.00 [deg], 26.00 [deg], 41.60 [deg], 52.00 [deg], which is incident on the photographing lens 110. The respective coma of the case is shown. The horizontal axis indicates the height of incidence on the imaging lens 110, and the vertical axis indicates lateral aberration (μm). FIG. 2B shows transverse aberration curves at the wavelengths of g-line, F-line, e-line, d-line, and c-line at the four angles of view described above. The value of the maximum scale of the lateral aberration amount is ± 20 μm. In each figure of FIG. 4, the horizontal axis of the figure on the left of two transverse aberration diagrams represents the relative pupil height y (ey) in the y direction, and the horizontal axis on the right represents the relative pupil height x in the x direction (Ex) is shown.

  FIG. 3 (a) shows the tangential plane (T) and the sagittal plane (S) at the wavelengths of g-line, F-line, e-line, d-line and c-line. Here, the tangential plane (or meridional plane) is a plane including the optical axis and the main optical axis, and the sagittal plane is a plane including the chief ray and perpendicular to the tangential plane. The vertical axis in FIG. 3A indicates the range of the viewing angle in the Y direction (the direction of the image height), and the horizontal axis indicates the amount of deviation of the focal point in the optical axis direction from the ideal plane image plane (mm) Indicates In the figure, T (g) to T (e) indicate curvature of field in the tangential plane of the above five wavelengths, and S (g) to S (e) indicate sagittal planes of the above five wavelengths. Indicates curvature of field at The defocus amount is ± 0.05 mm or less, which is a good value.

  In the graph showing distortion aberration in FIG. 3B, the vertical axis represents the real image height (Y), and the horizontal axis represents the distortion aberration percentage of the c-line. In this example, the value is as low as -20% or less.

  FIG. 3C is a graph showing lateral chromatic aberration based on the d-line. The vertical axis shows the image height, and the maximum field of view is 52 degrees. The horizontal axis indicates the amount of deviation of the reference wavelength from the d-line. The shift amount of the wavelength other than the reference wavelength is a value which substantially satisfies the tolerance of ± 1.5 μm.

  The graph of the MTF characteristic shown in FIG. 4 shows the relationship between the MTF value on the vertical axis and the image height shown on the horizontal axis. The MTF is an index indicating a change in contrast of an image formed on the image plane when the image plane is moved in the optical axis direction. As the MTF value is larger, it is determined that the image formed on the image plane is imaged at a higher resolution.

  In FIG. 4, the aerial frequency is fixed at 60 lines / mm, and the MTF values in the direction parallel to the sagittal plane (S1) and the direction parallel to the tangential plane (T1) are shown for the image height at this spatial frequency. The MTF value exceeds the allowable value of 0.4 (40%), indicating a high resolution. Further, the difference in resolution from the center to the periphery is about 20%, which indicates uniform resolution over the entire image plane.

Second Embodiment
The configuration of an imaging apparatus 200 according to Embodiment 2 of the present invention is shown in FIG. As shown in the figure, the imaging apparatus 200 includes a photographing lens 210 instead of the photographing lens 110 of the first embodiment. The photographing lens 210 includes a first lens 211 in place of the first lens 111 of the photographing lens 110. Except for this lens, the imaging device 200 of the second embodiment has the same configuration as the imaging device 100 of the first embodiment.

  The radius of curvature on the object side of the first lens 211 is larger than the radius of curvature on the object side of the first lens 111.

(Example 2)
As specific numerical values of the imaging lens 210 in Example 2 corresponding to the present embodiment, surface data, aspheric surface data, various types of data, and power values are shown below.

(Plane data)
Unit mm
Face number r d nd vd
Object ∞ ∞
1-42.222 1.20 1.80399 46.53
2 5.043 2.970
3 14.094 1.623 2.00272 19.32
4 114.096 1.811
5 (aperture) ∞ 0.065
6 18.850 2.819 1.83481 42.74
7-5.740 0.500 1. 76182 26.52
8 -11.369 1.765
9-7.044 0.700 1.92286 18.90
10 16.081 2.496 1.82080 32.32
11-16.081 0.200
12 * 16.406 2.496 1.82080 42.71
13 *-16.873 0.600
14 (filter) 0.8 0.8 15.1680 64.20
15 ∞ 6.756
Image plane ∞

  In the surface data, the lens surface of the surface number indicated with “* (asterisk)” is aspheric. A twelfth surface (S12) which is a surface on the object side of the seventh lens 117 of the photographing lens 210 and a thirteenth surface (S13) which is a surface on the image side are aspheric.

(Aspheric surface data)
The aspheric surface data of the 12th surface and the 13th surface are as follows.
12th
K = -0.030128858, A4 = 1.15309E-04, A6 = 3.45231E-06, A8 = -9.45677E-09, A10 = -7.61025E-10
13th surface
K = 0.11071436, A4 = 5.51429-E04, A6 = -7.39657E-07, A8 = 2.90565 E-07, A10 = -9.93471 E-09, A12 = 8.78794 E-11

(Various data)
F number = 1.6, maximum height increase = 4.32 mm, half angle of view (ω) = 52 °, total focal length = 5.362 mm, back focus (BF) = 8.16 mm, total lens length (TL) = 26.66 mm, diameter of aperture stop = 5.9 mm

(Power value)
First lens 211 = −0.181, second lens 112 = 0.063, third lens 113 = 0.056, fourth lens 114 = 0.079, first cemented lens 118 = 0. 120, the fifth lens 115 = -0.129, the sixth lens 116 = 0.061, the second cemented lens 119 =-0.058, the seventh lens 117 = 0.095

  Values of conditional expressions (1) to (5) of the photographing lens 210 are conditional expression (1) = − 7.87, conditional expression (2) = 3.51, conditional expression (3) = − 2.12, conditions Expression (4) = − 1.31, conditional expression (5) = 3.00, and conditional expressions (1) to (5) are satisfied.

  6 (a) shows spherical aberration, FIG. 6 (b) shows coma, FIG. 7 (a) shows curvature of field, and FIG. 7 (b) shows distortion. FIG. 8C is a graph showing the chromatic aberration of magnification, and FIG. 8 is a graph showing the MTF characteristics of the photographing lens.

  In the graph showing the spherical aberration in FIG. 6A, it is 0.04 mm or less at all frequencies, and the spherical aberration is well corrected. The coma aberration in FIG. 6 (b) is also properly corrected.

  In the graph showing the curvature of field in FIG. 7A, the defocus amount is ± 0.05 mm or less, which is a good value. The graph showing distortion in FIG. 7 (b) shows distortion as low as -20% or less. The magnification chromatic aberration in FIG. 7C substantially satisfies the tolerance of ± 1.5 μm.

  The MTF value shown in FIG. 8 exceeds the allowable value of 0.4 (40%), which indicates high resolution. Also, the difference in resolution from the center to the periphery is within 15%, indicating uniform resolution over the entire image plane.

Third Embodiment
The configuration of an imaging apparatus 300 according to Embodiment 3 of the present invention is shown in FIG. As shown in the figure, the imaging device 300 includes a photographing lens 310 in place of the photographing lens 110 of the first embodiment. The photographing lens 310 includes a third lens 313 in place of the third lens 113 of the photographing lens 110. Except for this lens, the imaging device 300 of Embodiment 3 has the same configuration as that of the imaging device 100 of Embodiment 1.

  The radius of curvature on the object side of the third lens 313 is larger than the radius of curvature on the object side of the third lens 113.

(Example 3)
The third embodiment is an example in which the horizontal angle of view of the photographing lens 110 is set to 77 degrees. As specific numerical values of the photographing lens 310, specification specifications, surface data, and power arrangement are shown below.

As specific numerical values of the imaging lens 310 in Example 3 corresponding to the present embodiment, surface data, aspheric surface data, various data, and power values are shown below.

(Plane data)
Unit mm
Face number r d nd vd
Object ∞ ∞
1 -40.401 1.20 1.80399 46.53
2 5.043 2.970
3 14.094 1.623 2.00272 19.32
4 114.096 1.811
5 (aperture) ∞ 0.065
6 19.25 2.819 1.83481 42.74
7-5.740 0.500 1. 76182 26.52
8 -11.369 1.765
9-7.044 0.700 1.92286 18.90
10 16.081 2.496 1.82080 32.32
11-16.081 0.200
12 * 16.406 2.496 1.82080 42.71
13 *-16.873 0.600
14 (filter) 0.8 0.8 15.1680 64.20
15 ∞ 6.756
Image plane ∞

  In the surface data, the lens surface of the surface number indicated with “* (asterisk)” is aspheric. A twelfth surface (S12) which is a surface on the object side of the seventh lens 117 of the photographing lens 310 and a thirteenth surface (S13) which is a surface on the image side are aspheric.

(Aspheric surface data)
The aspheric surface data of the 12th surface and the 13th surface are as follows.
12th
K = -0.030128858, A4 = 1.15309E-04, A6 = 3.45231E-06, A8 = -9.45677E-09, A10 = -7.61025E-10
13th surface
K = 0.11071436, A4 = 5.51429-E04, A6 = -7.39657E-07, A8 = 2.90565 E-07, A10 = -9.93471 E-09, A12 = 8.78794 E-11

(Various data)
F number = 1.6, maximum height increase = 4.32 mm, half angle of view (ω) = 38.5 °, total focal length = 5.369 mm, back focus (BF) = 8.26 mm, total lens length (TL) ) = 26.76 mm, diameter of aperture stop = 5.9 mm

(Power value)
The first lens 111 = -0.181, the second lens 112 = 0.063, the third lens 313 = 0.055, the fourth lens 114 = 0.079, the first cemented lens 118 = 0 117, fifth lens 115 = −0.129, sixth lens 116 = 0.061, second cemented lens 119 = −0.058, seventh lens 117 = 0.095

  Values of conditional expressions (1) to (5) of the photographing lens 310 are conditional expression (1) = − 7.52, conditional expression (2) = 3.58, conditional expression (3) = − 2.12, conditions Expression (4) = − 1.31, conditional expression (5) = 2.99, and conditional expressions (1) to (5) are satisfied.

  10 (a) shows spherical aberration, FIG. 10 (b) shows coma aberration, FIG. 11 (a) shows curvature of field, and FIG. 11 (b) shows distortion. FIG. 12C is a graph showing MTF characteristics of a photographing lens, showing chromatic aberration of magnification.

  In the graph showing the spherical aberration in FIG. 10A, it is 0.04 mm or less at all frequencies, and the spherical aberration is well corrected. The coma of FIG. 10 (b) is also properly corrected.

  In the graph showing the curvature of field in FIG. 11A, the defocus amount is ± 0.05 mm or less, which is a good value. The graph showing distortion in FIG. 11B shows distortion as low as −20% or less. The chromatic aberration of magnification in FIG. 11C substantially satisfies the tolerance of ± 1.5 μm.

  The MTF value shown in FIG. 12 exceeds the allowable value of 0.4 (40%), which indicates high resolution. Further, the difference in resolution from the center to the periphery is about 20%, which indicates uniform resolution over the entire image plane.

A lens which is out of the range of the conditional expression defined by the present invention will be described as Comparative Example 1 and Comparative Example 2.
(Comparative example 1)
The lens configuration of Comparative Example 1 is the same as that of Embodiment 1. The comparative example 1 is an example in which the radius of curvature on the object side of the first lens 111 and the radius of curvature on the image plane side of the first embodiment are changed. In particular, it is characterized in that the lens surface on the object surface side of the first lens is a convex surface. The lens sectional view is not shown.

Numerical examples of Comparative Example 1 are as follows.
(Plane data)
Unit mm
Face number r d nd vd
Object ∞ ∞
1 200.000 1.20 1.80399 46.53
2 4.323 2.970
3 14.094 1.623 2.00272 19.32
4 114.096 1.811
5 (aperture) ∞ 0.065
6 18.850 2.819 1.83481 42.74
7-5.740 0.500 1. 76182 26.52
8 -11.369 1.765
9-7.044 0.700 1.92286 18.90
10 16.081 2.496 1.82080 32.32
11-16.081 0.200
12 * 16.406 2.496 1.82080 42.71
13 *-16.873 0.600
14 (filter) 0.8 0.8 15.1680 64.20
15 ∞ 6.756
Image plane ∞

  In the surface data, the lens surface of the surface number indicated with “* (asterisk)” is aspheric. A twelfth surface (S12) which is a surface on the object side of the seventh lens 117 of the photographing lens 110 and a thirteenth surface (S13) which is a surface on the image side are aspheric.

(Aspheric surface data)
The aspheric surface data of the 12th surface and the 13th surface are as follows.
12th
K = -0.030128858, A4 = 1.15309E-04, A6 = 3.45231E-06, A8 = -9.45677E-09, A10 = -7.61025E-10
13th surface
K = 0.11071436, A4 = 5.51429-E04, A6 = -7.39657E-07, A8 = 2.90565 E-07, A10 = -9.93471 E-09, A12 = 8.78794 E-11

(Various data)
F number = 1.6, maximum height increase = 4.32 mm, half angle of view (ω) = 48 °, total system focal length = 5.410 mm, back focus (BF) = 8.30 mm, total lens length (TL) = 26.80 mm, diameter of aperture stop = 5.9 mm

(Power value)
First lens = −0.181, second lens = 0.063, third lens = 0.056, fourth lens = 0.079, first cemented lens = 0.120, fifth Lens = -0.129, sixth lens = 0.061, second cemented lens =-0.058, seventh lens = 0.095

  Values of conditional expressions (1) to (5) of the photographing lens are conditional expression (1) = 36.97, conditional expression (2) = 3.48, conditional expression (3) =-2.19, conditional expression ( 4) = − 1.30, the conditional expression (5) = 2.97, and the conditional expressions (2) to (5) are satisfied, but the conditional expressions (1) and (4) are not satisfied.

  The bluff of the MTF characteristic of the photographing lens having such numerical characteristics is shown in FIG. As shown in FIG. 13, both the MTF value in the tangential direction and the MTF value in the surgical direction are less than 0.4, which indicates that the imaging resolution is low.

(Comparative example 2)
The lens configuration of Comparative Example 2 is the same as that of Embodiment 1. Comparative Example 2 is an example in which the radius of curvature on the image plane side of the fifth lens 115 of Embodiment 1 is different.

Numerical examples of Comparative Example 2 are as follows.
(Plane data)
Unit mm
Face number r d nd vd
Object ∞ ∞
1 -40.401 1.20 1.80399 46.53
2 5.043 2.970
3 14.094 1.623 2.00272 19.32
4 114.096 1.811
5 (aperture) ∞ 0.065
6 18.850 2.819 1.83481 42.74
7-5.740 0.500 1. 76182 26.52
8 -11.369 1.765
9-7.300 0.700 1.92286 18.90
10 16.081 2.496 1.82080 32.32
11-16.081 0.200
12 * 16.406 2.496 1.82080 42.71
13 *-16.873 0.600
14 (filter) 0.8 0.8 15.1680 64.20
15 ∞ 6.756
Image plane ∞

  In the surface data, the lens surface of the surface number indicated with “* (asterisk)” is aspheric. A twelfth surface (S12) which is a surface on the object side of the seventh lens 117 of the photographing lens 110 and a thirteenth surface (S13) which is a surface on the image side are aspheric.

(Aspheric surface data)
The aspheric surface data of the 12th surface and the 13th surface are as follows.
12th
K = -0.030128858, A4 = 1.15309E-04, A6 = 3.45231E-06, A8 = -9.45677E-09, A10 = -7.61025E-10
13th surface
K = 0.11071436, A4 = 5.51429-E04, A6 = -7.39657E-07, A8 = 2.90565 E-07, A10 = -9.93471 E-09, A12 = 8.78794 E-11

(Various data)
F number = 1.6, maximum height increase = 4.32 mm, half angle of view (ω) = 54 °, total focal length = 5.217 mm, back focus (BF) = 8.16 mm, total lens length (TL) = 26.66 mm, diameter of aperture stop = 5.9 mm

(Power value)
First lens = −0.181, second lens = 0.063, third lens = 0.056, fourth lens = 0.079, first cemented lens = 0.120, fifth Lens = -0.124, sixth lens = 0.061, second cemented lens =-0.053, seventh lens = 0.095

  Values of conditional expressions (1) to (5) of the photographing lens are conditional expression (1) = − 7.74, conditional expression (2) = 3.61, conditional expression (3) = − 2.17, conditional expression (4) = − 1.39 and conditional expression (5) = 3.08, and the conditional expression (1) is satisfied, but the conditional expressions (2) to (5) are not satisfied.

  The bluff of the MTF characteristic of the photographing lens having such numerical characteristics is shown in FIG. As shown in FIG. 14, both the MTF value in the tangential direction and the MTF value in the surge plane direction are around 0.4, which indicates that the imaging resolution is low.

  The above embodiment and modifications are exemplifications, and the present invention is not limited to these, and various embodiments are possible without departing from the scope of the invention described in the claims. The components described in each embodiment and modification can be freely combined. The invention equivalent to the invention described in the claims is also included in the invention.

  The imaging lens according to the present invention is suitably applied to an optical device and the like, and the optical device includes an on-vehicle camera, a surveillance camera, an electronic device, various inspection devices, a camera mounted on a robot, a single-lens reflex camera, a compact camera, etc. including.

L Optical axis 100, 200, 300 Imaging device 101 Aperture 102 Secondary aperture 110, 210, 310 Shooting lens 111, 211 First lens 112 Second lens 113, 313 Third lens 114 Fourth lens 115 Fifth Lens 116 sixth lens 117 seventh lens 118 first cemented lens 119 second cemented lens 120 optical filter 130 imaging element P image plane

Claims (6)

From the object side,
A first lens having a negative power,
A second lens having a positive power,
A third lens having a positive power,
A fourth lens having a negative power,
A fifth lens having a negative power,
A sixth lens having a positive power,
And a seventh lens having a positive power,
The radius of curvature of the first lens on the object side is R1, the radius of curvature on the object side of the third lens is R6, the radius of curvature on the image plane side of the fourth lens is R8, and the object of the fifth lens Assuming that the curvature radius of the side is R9, the curvature radius of the image surface side of the sixth lens is R11, and the focal length of the entire system is f,
An imaging lens satisfying the following conditional expressions (1) to (5).
(1) -7.89 <R1 / f <-7.27
(2) 3.43 <R6 / f <3.60
(3) -2.16 <R8 / f <-2.09
(4) -1.34 <R9 / f <-1.30
(5)-3.07 <R11 / f <-2.94 The third lens and the fourth lens are cemented to form a first cemented lens having positive power, and the fifth lens and the sixth lens are cemented, Form a second cemented lens with negative power,
The photographing lens according to claim 1, characterized in that: The object-side surface of the first lens is concave,
The imaging lens according to claim 1. The seventh lens is an aspheric lens.
The imaging lens according to any one of claims 1 to 3. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are glass lenses.
The imaging lens according to any one of claims 1 to 4.   An imaging device comprising: the imaging lens according to any one of claims 1 to 5; and an imaging element configured to convert light transmitted through the imaging lens into an electric signal.

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