JP2008233610A - Imaging lens and imaging device equipped with the imaging lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging lens achieving not only excellent optical performance but also reduction in size and wide angle property. <P>SOLUTION: A negative first lens group G1, a positive second lens group G2, an aperture, and a positive third lens group G3 are arranged in this order from the object side. The first lens group G1 has at least two lenses. The second lens L12 of the first lens group G1 from the object side has a convex face directing the object side, and all of the lenses composing the first lens group G1 are negative. The second lens group G2 has at least one lens L21 of biconvex shape. The third lens group G3 has at least a negative lens L33 of meniscus shape and a positive lens L32 in this order from the closest side to the image. Abbe's number ν<SB>2</SB>of a lens L21 of the second lens group G2 to a d line satisfies the conditional expression (1), ν<SB>2</SB><43. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image pickup lens and an image pickup apparatus including the image pickup lens. More specifically, the present invention relates to an in-vehicle camera and a mobile terminal using an image pickup device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The present invention relates to a wide-angle imaging lens suitable for use in cameras, surveillance cameras, and the like, and an imaging device including the imaging lens.

  In recent years, image sensors such as CCDs and CMOSs have been greatly reduced in size and pixels. At the same time, the image pickup device body including these image pickup devices is also downsized, and the image pickup lens mounted thereon is also required to be downsized and light.

  On the other hand, in-vehicle cameras, surveillance cameras, and the like, there is a demand for a small-sized wide-angle lens that can be used in a wide temperature range while having high weather resistance from the outside air in a cold region to the interior of a tropical summer car.

As imaging lenses in the above field, those described in Patent Documents 1 to 4 below are known. Patent Document 1 describes a fish-eye lens composed of 6 elements in 5 groups. Patent Document 2 describes a wide-angle lens that includes 6 elements in 5 groups or 7 elements in 5 groups and includes an aspheric lens. Patent Document 3 describes a wide-angle lens composed of 6 elements in 5 groups or 7 elements in 5 groups, which is used for a small camera of a surveillance television. Patent Document 4 describes a wide-angle lens composed of 7 elements in 6 groups.
U.S. Pat. No. 7,023,628 Japanese Patent No. 2599312 JP 61-123810 A JP-A-4-246606

  Patent Document 1 describes a bright lens having an F value of 2, but there is a drawback in that the cost increases because a glass material having a refractive index exceeding 1.9 is frequently used. Since the lenses described in Patent Document 2 and Patent Document 4 use aspherical lenses, if the material is made of glass, this also increases the cost, which is not preferable. The lens described in Patent Document 3 is a dark optical system with an F value of 2.8 to 4 in addition to insufficient widening and miniaturization.

  In view of the above circumstances, an object of the present invention is to provide a small and wide-angle imaging lens and an imaging apparatus including the imaging lens while maintaining good optical performance.

The first imaging lens of the present invention includes, in order from the object side, a first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, a stop, and a positive as a whole. A third lens group having a refractive power, the first lens group has at least two lenses, and the second lens from the object side of the first lens group has a convex surface facing the object side. All of the lenses constituting the first lens group are negative lenses, the second lens group has at least one biconvex lens, and the third lens group is at least in order from the most image side. It has a negative meniscus lens and a positive lens, and the Abbe number ν ₂ with respect to the d-line of the biconvex lens of the second lens group satisfies the following conditional expression (1). .
ν ₂ <43 (1)

  The first imaging lens of the present invention has a first lens group composed of a negative lens having the above-described shape, thereby reducing the size and widening the angle while suppressing the occurrence of distortion well. Has a second lens group having a positive refractive power including a biconvex lens that is preferably selected, so that the curvature of field and the chromatic aberration of magnification are favorably corrected, and a third lens group including a negative lens and a positive lens Accordingly, it is possible to satisfactorily correct lateral chromatic aberration and axial chromatic aberration, to ensure good optical performance, and to provide a small and wide-angle imaging lens.

  The second imaging lens of the present invention includes, in order from the object side, a first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, a stop, and a positive as a whole. A third lens group having refractive power, and the first lens group includes, in order from the object side, a negative first lens having a convex surface directed toward the object side and a negative lens having a convex surface directed toward the object side. The second lens group includes a negative third lens having a concave surface facing the image side. The second lens group includes only a biconvex single lens, and the third lens group is the most image side. In this order, at least a negative meniscus lens and a positive lens are included.

  The second imaging lens of the present invention has a first lens group composed of a negative lens having the above-described shape, thereby reducing the size and widening of the lens while further suppressing the occurrence of distortion. By having the second lens group composed of a convex lens, the curvature of field is favorably corrected, and by having the third lens group including a negative lens and a positive lens, lateral chromatic aberration and axial chromatic aberration are favorably corrected, The present invention provides a small and wide-angle imaging lens while ensuring good optical performance.

  In the first and second imaging lenses of the present invention, the third lens group includes, in order from the object side, a positive single lens having a surface with a smaller absolute value of the radius of curvature facing the image side, and a positive lens. And a cemented lens of a negative meniscus lens.

In the first and second imaging lenses of the present invention, in the third lens group, the refractive index N _n and the Abbe number ν _n with respect to the d line of the negative meniscus lens closest to the image side, and the image side It is preferable that the refractive index N _p and the Abbe number ν _p for the d-line of the second positive lens from the first to the second lens satisfy the following conditional expressions (2) and (3).
0.05 <N _n −N _p <0.45 (2)
1.5 <ν _p / ν _n (3)
In the first and second imaging lenses of the present invention described above, the focal length f of the entire system, the negative meniscus lens closest to the image side in the third lens group, and the second positive lens from the image side. It is preferable that the combined focal length f _{pn of the} lens satisfies the following conditional expression (4).
3 <f _pn / f <30 (4)
In the first and second imaging lenses of the present invention, the focal length f of the entire system and the combined focal length f _G1 of the first lens group satisfy the following conditional expression (5). preferable.
-2 _<f G1 /f<-0.5 (5)
In the first and second imaging lenses of the present invention, the focal length f of the entire system and the object-side surface of the most object-side lens in the first lens group to the image-side focal plane of the entire system. It is preferable that the distance L on the optical axis satisfies the following conditional expression (6).
7 <L / f <14 (6)
Further, in the first and second imaging lenses of the present invention, the third lens group, in order from the object side, a positive single lens having a surface with a smaller absolute value of the curvature radius toward the image side, In the case where the lens is composed of a cemented lens of a positive lens and a negative meniscus lens, the film for blocking infrared light is the image side surface of the single lens closest to the object side in the third lens group Is preferably applied.

  An imaging apparatus according to the present invention includes the imaging lens 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, an imaging lens capable of achieving a reduction in size and a wide angle while ensuring good optical performance by appropriately selecting the shape or material of the lens, and an imaging equipped with the imaging lens An apparatus can be provided.

  Hereinafter, embodiments of an imaging lens of the present invention and an imaging device including the imaging lens will be described in detail with reference to the drawings. The imaging lens of the present embodiment can be used for an in-vehicle camera, a mobile terminal camera, a surveillance camera, and the like, and particularly in an in-vehicle camera for capturing images of the front, side, rear, etc. of an automobile. It can be suitably used. As a usage example, FIG. 1 shows a state in which an imaging lens and an imaging apparatus of the present embodiment are mounted on an automobile 1.

  In FIG. 1, an automobile 1 includes an outside camera 2 for imaging a blind spot range on the side surface on the passenger seat side, an outside camera 3 for imaging a blind spot range on the rear side of the automobile 1, and a rear surface of a rearview mirror. An in-vehicle camera 4 is provided for photographing the same field of view as the driver. The camera 2 outside the vehicle, the camera 3 outside the vehicle, and the camera 4 inside the vehicle are imaging devices, and include an imaging lens 5 and an imaging element 6 that converts an optical image formed by the imaging lens 5 into an electrical signal.

  FIG. 2 is a cross-sectional view of an optical system of a configuration example of the imaging lens 5 according to the embodiment of the present invention. The configuration example shown in FIG. 2 corresponds to the lens configuration of Example 1 described later. The imaging lens 5 includes a first lens group G1 having a negative refractive power as a whole, and a second lens group G2 having a positive refractive power as a whole, in order from the object side along the optical axis Z. An aperture stop St and a third lens group G3 having a positive refractive power as a whole are arranged.

  In the imaging lens 5 of the example shown in FIG. 2, the first lens group G1 includes a lens L11 and a lens L12, the second lens group G2 includes a lens L21, and the third lens group G3 includes a lens L31. And a cemented lens LC in which the lens L32 and the lens L33 are cemented.

  On the imaging surface of the imaging lens 5, an imaging surface of an imaging device 6 that is a solid-state imaging device such as a CCD image sensor is disposed. Between the imaging lens 5 and the imaging element 6, various flat plate-like optical members PP such as a cover glass for protecting the imaging surface and an infrared cut filter are arranged according to the configuration on the camera side where the lens is mounted. .

  In the imaging lens 5, the light flux that passes outside the effective diameter between the lens L <b> 11 and the lens L <b> 12 becomes stray light and reaches the image plane, which may become a ghost. Note that a light beam 7 in FIG. 1 indicates a light beam incident at the maximum angle of view. Since the light beam that passes outside the light beam 7 may become stray light, it is preferable to provide the light shielding means 11 between the lens L11 and the lens L12 to block the stray light. As the light shielding means 11, for example, an opaque paint may be applied to a portion outside the effective diameter on the lens L12 side of the lens L11, or an opaque plate material may be provided, or a lens L11 and a lens L12 of a light beam that becomes stray light. An opaque plate material may be provided in the optical path between the two. Further, such a light shielding means for the purpose may be disposed not only between the lens L11 and the lens L12 but also between other lenses as necessary. In FIG. An example in which the light shielding means 12 having the same configuration as that of the light shielding means 11 is also applied to the portion is shown.

  Next, a detailed configuration of the imaging lens 5 and its operation and effect will be described. The first lens group G1 has at least two lenses, the second lens from the object side of the first lens group G1 has a convex surface facing the object side, and all the lenses constituting the first lens group G1 are negative. It is comprised so that it may become a lens.

  By selecting the refractive power and shape of the lenses of the first lens group G1 as described above, it is possible to achieve a reduction in size and a wide angle while satisfactorily suppressing the occurrence of distortion. Further, by making all the lenses constituting the first lens group G1 negative lenses, the first lens group G1 can have a strong negative refractive power. In order to reduce the size and widen the angle, a group in which the first lens group G1 having a negative refractive power and the second lens group G2 having a positive refractive power are combined as a whole has a negative refractive power or a weak positive power. The first lens group G1 preferably has a sufficiently strong negative refractive power from this viewpoint.

  Here, when the lens L11 is formed of a meniscus lens having a convex surface facing the object side as in the example shown in FIG. 2, a light beam having a large incident angle can be captured on the convex surface on the object side of the lens L11. The angle of the system can be widened, and the luminous flux after exiting the lens L11 can be made thin, so that downsizing can be realized. Moreover, the Petzval sum can be reduced by using a negative meniscus lens, and the field curvature can be corrected over the entire wide screen.

  Since the lens L11 is the most object side lens, for example, when used in a harsh environment such as a vehicle-mounted camera, the lens L11 is resistant to surface deterioration due to wind and rain, temperature change due to direct sunlight, and further, oils and detergents, etc. It is preferable to use a material resistant to chemicals, that is, a material having high water resistance, weather resistance, acid resistance, chemical resistance and the like. Further, as the material of the lens L11, it is preferable to use a hard and hard-to-break material. Specifically, it is preferable to use glass or transparent ceramics. Ceramics has properties of higher strength and higher heat resistance than ordinary glass.

  In the example shown in FIG. 2, the first lens group G1 is composed of two negative lenses. However, the first lens group G1 is composed of three or more negative lenses by adding a negative lens to the image side of the lens L12. You may make it do.

  For example, as shown in Examples 9 to 12 described later and FIGS. 11 to 14 of the configuration diagrams thereof, the first lens group G1 is arranged in order from the object side, a negative lens L11 having a convex surface facing the object side, and an object A negative lens L12 having a convex surface on the side and a negative lens L13 having a concave surface on the image side can also be used. In the case of such a configuration, it is possible to achieve a reduction in size and a wide angle while further suppressing the occurrence of distortion.

The second lens group G2 is configured to have at least one biconvex lens. And the Abbe number ν ₂ for the d-line of the biconvex lens is
ν ₂ <43 (1)
The material is preferably selected so that By selecting the material so as to satisfy the conditional expression (1), the chromatic aberration of magnification can be corrected well.

  In the example shown in FIG. 2, the second lens group G2 includes only a lens L21, which is a biconvex single lens. The lens L21 is disposed in the vicinity of the position of the aperture stop St where light rays are densely concentrated, and acts in a direction to converge divergent light emitted from the lenses L11 and L12, which are negative lenses. By making the lens L21 into a biconvex shape, it is possible to have a strong positive refractive power and to correct field curvature well.

  In order to reduce the number of lenses, the second lens group G2 is preferably composed of only a biconvex single lens, but may be composed of other lenses.

  The third lens group G3 is configured to include at least a negative meniscus lens and a positive lens in order from the most image side. By thus arranging positive and negative lenses on the image side, it is possible to satisfactorily correct lateral chromatic aberration and axial chromatic aberration.

  In the example illustrated in FIG. 2, the third lens group G3 includes a lens L31 that is a positive single lens with a surface having a smaller absolute value of the curvature radius facing the image side in order from the object side, and a positive lens. It consists of a lens L32 and a cemented lens LC of a lens L33 that is a negative meniscus lens.

  By making the lens L31 in the above shape, the curvature of field can be corrected well. Furthermore, if the lens L31 is a planoconvex lens or a biconvex lens, the field curvature can be corrected more favorably.

  By using a cemented lens instead of the lens L32 and the lens L33 as separate lenses, it is possible to more appropriately correct lateral chromatic aberration and axial chromatic aberration. Further, when the positive lens L32 has a biconvex shape, the refractive power can be increased, which is advantageous in correcting chromatic aberration.

In the third lens group G3, the refractive index N _n and Abbe number ν _n of the negative meniscus lens (lens L33) closest to the image side with respect to the d line, and the d line of the second positive lens (lens L32) from the image side. It is preferable that the refractive index N _p and the Abbe number ν _p satisfy the following conditional expressions (2) and (3).
0.05 <N _n −N _p <0.45 (2)
1.5 <ν _p / ν _n (3)
If the lower limit of conditional expression (2) is exceeded, the radius of curvature of the joint surface becomes small, and machining becomes difficult. If the upper limit of conditional expression (2) is exceeded, the materials that can be used in practice are limited, and the materials that can be used become expensive, which is an obstacle to cost reduction. If the lower limit of conditional expression (3) is exceeded, it will be difficult to satisfactorily correct chromatic aberration.

In the imaging lens 5, the focal length f of the entire system and the combined focal length of the negative meniscus lens closest to the image side and the second positive lens from the image side in the third lens group G3 (the combined focal length of the cemented lens LC) It is preferable that f _pn satisfies the following conditional expression (4).
3 <f _pn / f <30 (4)
If the lower limit of conditional expression (4) is exceeded, it will be difficult to correct field curvature well. When the upper limit of conditional expression (4) is exceeded, the combined refractive power of the negative meniscus lens closest to the image side and the second positive lens from the image side in the third lens group G3 becomes weak, and chromatic aberration is corrected well. It becomes difficult.

In the imaging lens 5, it is preferable that the focal length f of the entire system and the combined focal length f _G1 of the first lens group G1 satisfy the following conditional expression (5).
-2 _<f G1 /f<-0.5 (5)
If the lower limit of conditional expression (5) is exceeded, widening of the angle can be easily achieved, but the field curvature becomes large and it becomes difficult to obtain a good image. If the upper limit of conditional expression (5) is exceeded, it will be difficult to achieve a wide angle, or the lens system will be enlarged.

In the imaging lens 5, the focal length f of the entire system, and the distance L on the optical axis from the object-side surface of the most object-side lens (lens L11) of the first lens group G1 to the image-side focal plane of the entire system. However, it is preferable that the following conditional expression (6) is satisfied.
7 <L / f <14 (6)
If the lower limit of conditional expression (6) is exceeded, widening the angle becomes difficult. If the upper limit of conditional expression (10) is exceeded, the lens system will be enlarged.

Further, in the imaging lens 5, it is preferable that the combined focal length f _G1G2 of the group obtained by combining the first lens group G1 and the second lens group G2 satisfies the following conditional expression (7) or conditional expression (8).
300 <f _G1G2 (7)
f _G1G2 <0 (8)
The group obtained by combining the first lens group G1 and the second lens group G2 preferably has a negative refractive power or a weak positive refractive power as a whole. This is because if the combined group of the first lens group G1 and the second lens group G2 has a strong positive refractive power as a whole, it is difficult to widen the angle or the lens system becomes large.

  By making the combined focal length of the first lens group G1 and the second lens group G2 within the range of the conditional expression (7) or (8), widening and miniaturization can be achieved at the same time. If the combined focal length of the first lens group G1 and the second lens group G2 is out of the range of conditional expressions (7) and (8), it will be difficult to achieve a wide angle, or the lens system will be enlarged. .

In the imaging lens 5, and the focal length f of the entire system, and the center thickness D ₁ of the lens L11, it is preferable to satisfy the following conditional expression (9).
_{0.4 <D 1 / f (9} )
For example, when the imaging lens 5 is used for an application such as a vehicle, the lens L11 is required to have strength against various impacts. When the lower limit of conditional expression (9) is exceeded, the lens L11 becomes thin and easily cracked, and the strength against various impacts becomes weak.

In the imaging lens 5, it is preferable that the focal length f of the entire system and the combined focal length f _G3 of the third lens group G3 satisfy the following conditional expression (10).
1.7 <f _G3 /f<3.0 (10)
When the lower limit of conditional expression (10) is exceeded, the back focus becomes short, and it becomes difficult to dispose an optical member PP such as a cover glass or a filter between the imaging lens 5 and the imaging element 6. If the upper limit of conditional expression (10) is exceeded, it will be difficult to satisfactorily correct field curvature.

In the imaging lens 5, it is preferable that the Abbe number ν _n with respect to the d line of the negative meniscus lens (lens L33) closest to the image side in the third lens group G3 satisfies the following conditional expression (11).
ν _n <20 (11)
When ν _n satisfies the conditional expression (11), the Abbe number of the negative meniscus lens (lens L33) closest to the image side and the second positive lens (lens L32) from the image side in the third lens group G3. Therefore, it is easy to correct axial chromatic aberration and magnification chromatic aberration.

  In the imaging lens 5, the third lens group G <b> 3 is a positive lens, a lens L <b> 31, which is a positive single lens with a surface having a smaller absolute value of the curvature radius facing the image side in order from the object side. In the case of a lens configuration composed of the lens L32 and the cemented lens LC of the lens L33, which is a negative meniscus lens, the film for blocking infrared light is a single lens (most object side of the third lens group G3) It is preferable to be applied to the image side surface of the lens L31). As a result, the generation of ghosts can be minimized, and there is no need to insert a filter for cutting infrared light into the lens system. In addition, when a film for blocking infrared light is applied to the third lens group G3 other than the image side surface of the single lens closest to the object side, a strong ghost caused by this film is likely to occur. Is not preferable.

  In the imaging lens 5, the material of the lens is preferably a material having low ultraviolet light transmittance. The spectral transmittance of a general lens material tends to decrease as it goes from the visible light region to the ultraviolet light region. The imaging lens 5 preferably includes at least one lens formed of a material having a wavelength of 360 nm or more at which the transmittance is 5% in the decreasing curve. As a result, it is possible to omit a filter or film formation for shielding ultraviolet light, and to reduce the cost of the entire lens system.

  When the imaging lens 5 is applied to, for example, a vehicle-mounted camera, it is required that the imaging lens 5 can be used in a wide temperature range from the outside air in a cold region to the interior of a tropical summer vehicle. Therefore, it is preferable that the material of all the lenses is glass. Specifically, it is preferable that it can be used in a wide temperature range of −40 ° C. to 125 ° C. In order to manufacture lenses at low cost, it is preferable that all the lenses are spherical lenses.

  Next, specific numerical examples of the imaging lens 5 according to the present embodiment will be described. Among the examples described below, Examples 1 to 8, 13, and 14 have a six-sheet configuration, and Examples 9 to 12 have a seven-sheet configuration.

<Example 1>
Table 1 shows specification values, design specifications, and focal lengths of the imaging lens according to the first example. In Table 1, Si indicates the i-th (i = 1 to 15) surface number that sequentially increases toward the image side with the surface of the component closest to the object side as the first. Ri represents the radius of curvature of the i-th (i = 1 to 15) surface, and Di represents the surface interval on the optical axis Z between the i (i = 1 to 14) -th surface and the i + 1-th surface. Ndj represents the refractive index with respect to the d-line (wavelength: 587.6 nm) of the j-th lens (j = 1 to 7) or the optical member PP that sequentially increases toward the image side with the most object-side lens as the first. , Νdj represents the Abbe number with respect to the d-line of the j-th lens or optical member PP. In Table 1, the unit of the radius of curvature and the surface interval is mm, and the radius of curvature is positive when convex on the object side and negative when convex on the image side.

In Table 1, FNo. Is the F value, L ′ is the distance on the optical axis Z from the object-side surface of the lens L11 to the image-side focal plane when the optical member PP is between the lens L33 and the image plane, and L is the lens L11 The distance on the optical axis Z from the object-side surface to the image-side focal plane (the optical member PP is converted into air), f is the focal length of the entire system, and f _G1 is the combined focal length of the first lens group G1. , F _G2 is the combined focal length of the second lens group G2, f _G3 is the combined focal length of the third lens group G3, f _G1G2 is the combined focal length of the first lens group G1 and the second lens group G2, and f _G2G3 is the first focal length. The combined focal length of the second lens group G2 and the third lens group G3, f _pn is the combined focal length of the cemented lens LC. The meanings of the symbols in the table are the same for the examples described later.

  A lens configuration diagram of Example 1 is shown in FIG. The symbols Ri (i = 1 to 14) and Di (i = 1 to 14) in FIG. 3 correspond to Ri and Di in Table 1. The aperture stop St in FIG. 3 does not indicate the shape or size, but indicates the position on the optical axis Z. The reference numerals in Table 1 and FIG. 3 include the aperture stop St and the optical member PP. In FIG. 3, the imaging surface 6 a of the imaging device 6 is illustrated as an imaging surface.

<Example 2>
Table 2 shows the specification values of the imaging lens according to Example 2, and FIG. In FIG. 4, symbols Ri and Di correspond to Ri and Di in Table 2.

<Example 3>
Table 3 shows specification values of the imaging lens according to Example 3, and FIG. 5 shows a lens configuration diagram. In FIG. 5, symbols Ri and Di correspond to Ri and Di in Table 3.

<Example 4>
Table 4 shows the specification values of the imaging lens according to Example 4, and FIG. In FIG. 6, symbols Ri and Di correspond to Ri and Di in Table 4.

<Example 5>
Table 5 shows specification values of the imaging lens according to Example 5, and FIG. 7 shows a lens configuration diagram. In FIG. 7, symbols Ri and Di correspond to Ri and Di in Table 5.

<Example 6>
Table 6 shows specification values of the imaging lens according to Example 6, and FIG. 8 shows a lens configuration diagram. In FIG. 8, symbols Ri and Di correspond to Ri and Di in Table 6.

<Example 7>
Table 7 shows specification values of the imaging lens according to Example 7, and FIG. 9 shows a lens configuration diagram. In FIG. 9, symbols Ri and Di correspond to Ri and Di in Table 7.

<Example 8>
Table 8 shows specification values of the imaging lens according to Example 8, and FIG. 10 shows a lens configuration diagram. In FIG. 10, symbols Ri and Di correspond to Ri and Di in Table 8.

  In Examples 9 to 12 described below, the first lens group G1 includes three lenses, which are a lens L11, a lens L12, and a lens L13, and this point is described in Examples 1 to 8 described above. Different from Examples 13 and 14.

<Example 9>
Table 9 shows specification values of the imaging lens according to Example 9, and FIG. 11 shows a lens configuration diagram. In FIG. 11, symbols Ri and Di correspond to Ri and Di in Table 9.

<Example 10>
Table 10 shows specification values of the imaging lens according to Example 10, and FIG. 12 shows a lens configuration diagram. In FIG. 12, symbols Ri and Di correspond to Ri and Di in Table 10.

<Example 11>
Table 11 shows specification values of the imaging lens according to Example 11, and FIG. 13 is a lens configuration diagram. In FIG. 13, symbols Ri and Di correspond to Ri and Di in Table 11.

<Example 12>
Table 12 shows specification values of the imaging lens according to Example 12, and FIG. 14 is a lens configuration diagram. In FIG. 14, symbols Ri and Di correspond to Ri and Di in Table 12.

<Example 13>
Table 13 shows specification values of the imaging lens according to Example 13, and FIG. 15 shows a lens configuration diagram. In FIG. 15, symbols Ri and Di correspond to Ri and Di in Table 13.

<Example 14>
Table 14 shows specification values of the imaging lens according to Example 14, and FIG. 16 shows a lens configuration diagram. In FIG. 16, symbols Ri and Di correspond to Ri and Di in Table 14.

  Table 15 shows values corresponding to the conditional expressions (1) to (5) in the imaging lenses of Examples 1 to 14, and Table 16 shows values corresponding to the conditional expressions (6) to (11). As can be seen from Tables 15 and 16, all of the imaging lenses of Examples 1 to 4 and 7 to 14 satisfy all the conditional expressions (1) to (11). In addition, the imaging lenses of Examples 5 and 6 satisfy the conditional expressions (1) to (8), (10), and (11). In this case, conditional expressions (7) and (8) are collectively treated as satisfying one of conditional expressions (7) and (8).

  Aberration diagrams of spherical aberration, astigmatism, distortion (distortion), and lateral chromatic aberration of the imaging lenses according to Examples 1 to 14 are shown in FIGS. Each aberration diagram shows an aberration with the e-line (wavelength 546.07 nm) as a reference wavelength. The spherical aberration diagram and the lateral chromatic aberration diagram show the F-line (wavelength 486.1 nm) and C-line (wavelength 656.3 nm). The aberration for) is also shown. In the distortion diagram, the ideal image height is fω (the product of the focal length f of the entire system and the half field angle ω), and the amount of deviation therefrom is shown. FNo. On the vertical axis of the spherical aberration diagram. Is an F value, and ω on the vertical axis of other aberration diagrams indicates a half angle of view. As can be seen from FIG. 17 to FIG. 30, the aberrations in Examples 1 to 14 are corrected satisfactorily.

  The present invention has been described with reference to the embodiment and examples. However, the present invention is not limited to the above embodiment and example, and various modifications can be made. For example, the values of the radius of curvature, the surface interval, and the refractive index of each lens component are not limited to the values shown in the above numerical examples, but can take other values.

  In the above embodiment, the example in which the present invention is applied to an in-vehicle camera has been described. However, the present invention is not limited to this application, and can be applied to, for example, a mobile terminal camera or a surveillance camera. is there.

The figure for demonstrating arrangement | positioning of the vehicle-mounted imaging device concerning embodiment of this invention 1 is a cross-sectional view of an optical system of a configuration example of an imaging lens according to an embodiment of the present invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 1 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 2 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 3 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 4 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 5 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 6 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 7 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 8 of this invention. Sectional view showing the lens configuration of an imaging lens according to Example 9 of the present invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 10 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 11 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 12 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 13 of this invention. Sectional drawing which shows the lens structure of the imaging lens concerning Example 14 of this invention. Each aberration diagram of the imaging lens according to Example 1 of the present invention Each aberration diagram of the imaging lens according to Example 2 of the present invention Each aberration diagram of the imaging lens according to Example 3 of the present invention Each aberration diagram of the imaging lens according to Example 4 of the present invention Each aberration diagram of the imaging lens according to Example 5 of the present invention Each aberration diagram of the imaging lens according to Example 6 of the present invention Each aberration diagram of the imaging lens according to Example 7 of the present invention Respective aberration diagrams of the imaging lens according to the eighth embodiment of the present invention Each aberration diagram of the imaging lens according to Example 9 of the present invention Each aberration diagram of the imaging lens according to Example 10 of the present invention Each aberration diagram of the imaging lens according to Example 11 of the present invention Respective aberration diagrams of the imaging lens according to the twelfth embodiment of the present invention. Each aberration diagram of the imaging lens according to Example 13 of the present invention Each aberration diagram of the imaging lens according to Example 14 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car 2, 3 Outside camera 4 In-vehicle camera 5 Imaging lens 6 Image pick-up element 6a Imaging surface 7 Light beam 11, 12 Light-shielding means Di The surface interval on the optical axis of i-th surface and i + 1-th surface G1 1st lens group G2 2nd lens group G3 3rd lens group L11, L12, L13, L21, L31, L32, L33 Lens LC Joint lens PP Optical member Ri Radius of curvature St Aperture stop Z Optical axis

Claims (9)

In order from the object side, a first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, a stop, and a third lens group having a positive refractive power as a whole Arranged,
The first lens group has at least two lenses, the second lens from the object side of the first lens group has a convex surface facing the object side, and all the lenses constituting the first lens group are negative. Lens,
The second lens group has at least one biconvex lens;
The third lens group has at least a negative meniscus lens and a positive lens in order from the most image side,
An imaging lens, wherein an Abbe number ν ₂ with respect to the d-line of the biconvex lens of the second lens group satisfies the following conditional expression (1).
ν ₂ <43 (1) In order from the object side, a first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, a stop, and a third lens group having a positive refractive power as a whole Arranged,
The first lens group includes, in order from the object side, a negative first lens having a convex surface facing the object side, a negative second lens having a convex surface facing the object side, and a negative first lens having a concave surface facing the image side. It consists of three lenses,
The second lens group is composed of only a biconvex single lens,
The imaging lens, wherein the third lens group includes at least a negative meniscus lens and a positive lens in order from the most image side.   The third lens group includes, in order from the object side, a positive single lens having a surface with a smaller radius of curvature toward the image side, and a cemented lens of a positive lens and a negative meniscus lens. The imaging lens according to claim 1, wherein the imaging lens is provided. In the third lens group, the refractive index N _n and Abbe number ν _n for the d-line of the negative meniscus lens closest to the image side, the refractive index N _p for the d-line of the second positive lens from the image side, and 4. The imaging lens according to claim 1, wherein the Abbe number ν _p satisfies the following conditional expressions (2) and (3): 5.
0.05 <N _n −N _p <0.45 (2)
1.5 <ν _p / ν _n (3) The focal length f of the entire system and the combined focal length f _{pn of the} negative meniscus lens closest to the image side and the second positive lens from the image side in the third lens group _{satisfy the following} conditional expression (4): The imaging lens according to claim 1, wherein the imaging lens is satisfied.
3 <f _pn / f <30 (4) 6. The imaging lens according to claim 1, wherein a focal length f of the entire system and a combined focal length f _G1 of the first lens group satisfy the following conditional expression (5): .
-2 _<f G1 /f<-0.5 (5) The focal length f of the entire system and the distance L on the optical axis from the object-side surface of the lens closest to the object side of the first lens group to the image-side focal plane of the entire system satisfy the following conditional expression (6): The imaging lens according to claim 1, wherein the imaging lens is satisfied.
7 <L / f <14 (6)   8. The film according to claim 3, wherein a film for blocking infrared light is provided on an image side surface of the single lens closest to the object side of the third lens group. 9. Imaging lens. The imaging lens according to any one of claims 1 to 8,
An image sensor that converts an optical image formed by the imaging lens into an electrical signal;
An imaging apparatus comprising:

Images