JP6270177B2 - Imaging lens, imaging device, and information device - Google Patents

Description

  The present invention relates to improvement of a single-focus imaging lens for forming a subject image in various cameras including a so-called silver salt camera, in particular, a digital camera and a video camera, and more particularly to a digital camera, a digital video camera, and the like. An imaging lens suitable as an imaging optical system in an imaging apparatus using an electronic imaging means, an imaging apparatus such as a camera using such an imaging lens, and an information apparatus such as a portable information terminal apparatus having an imaging function It is about.

The market for so-called digital cameras that acquire digital image data of a subject using a solid-state imaging device is a very large market, and the demands of users for this type of digital camera are also diverse. Among them, the category of high-quality compact cameras using a relatively large image sensor with a diagonal length of about 20 mm to 45 mm and equipped with an imaging lens composed of a high-performance single-focus optical system is highly expected by users. Has been sent. As a request from users, in addition to high performance, there is a high weight for excellent portability, that is, small size.
Here, in terms of performance enhancement, in addition to having a resolution corresponding to at least an image sensor with 12 to 24 million pixels, there is little coma flare from the wide open aperture, high contrast, and an angle of view. It is necessary that the point image is not disturbed to the peripheral part, the chromatic aberration is small, unnecessary coloring is not generated even in a portion having a large luminance difference, the distortion is small, and a straight line can be drawn as a straight line.
Further, in terms of increasing the diameter, an F value of at least about F2.8 is necessary because it is necessary to differentiate from a general compact camera equipped with a zoom lens.
And in terms of miniaturization, the actual focal length becomes longer due to the relatively large imaging device, so the total length is shorter when normalized with the focal length or maximum image height than when using a small imaging device. It is necessary to become.

In addition, regarding the angle of view of the taking lens, there are many users who desire a certain wide angle, and it is desirable that the half angle of view of the imaging lens is 35 degrees or more. A half field angle of 35 degrees corresponds to a focal length of about 31 mm in terms of a lens for a 35 mm silver salt camera (so-called Leica size).
Many types of optical systems are conceivable as imaging lenses used in this type of digital camera, but a typical configuration of a wide-angle single focus lens is a lens group having a negative refractive power on the object side and a positive lens on the image side. There is a so-called retrofocus type optical system in which a lens group having a refractive power of 2 is arranged. Due to the characteristics of the area sensor as an image sensor that has a color filter or microlens for each pixel, there is a need to move the exit pupil position away from the image plane so that the peripheral luminous flux is incident on the area sensor at an angle as close as possible to the area sensor. This is the main reason why a retrofocus type optical system is adopted. However, the retro-focus type optical system was originally used to secure the back focus because the wide-angle lens was used as an interchangeable lens for single-lens reflex (single-lens reflex) cameras. The total length (distance from the object side surface to the image plane) tends to be large.

On the other hand, in recent years, in relatively large image sensors with a diagonal length of about 20 mm to 45 mm, peripheral light flux is incident on the sensor at a certain angle due to improvements and optimization of on-chip microlenses and advances in image processing. Even so, the situation is not becoming a big problem. Specifically, it is possible to construct a system that is sufficiently acceptable even when the angle between the principal ray and the optical axis is about 35 to 40 degrees at the maximum image height. Accordingly, it has become possible to select a lens type that is more suitable for miniaturization without being particular about the vertical incidence of the peripheral luminous flux as before.
Under such circumstances, as a lens-type optical system that is more suitable for miniaturization than a retrofocus-type optical system, a telephoto lens having a substantially symmetric type or a lens group having negative refractive power on the image side is provided. Type of optical system.
Examples of conventional imaging lenses of the lens type as described above include, for example, Patent Document 1 (Japanese Patent Laid-Open No. 8-313802), Patent Document 2 (Japanese Patent Laid-Open No. 11-326756), and Patent Document 3 (Japanese Patent Application Laid-Open No. 11-326756). No. 2005-352060) and the like, and further disclosed in Japanese Patent Application Laid-Open No. 2012-8347.

However, the configuration of the optical system disclosed in Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4 described above is not sufficient in terms of downsizing or increasing the diameter.
That is, the optical system disclosed in Patent Document 1 is a substantially symmetric wide-angle lens and has a sufficiently large aperture, but the lens is the distance from the most object side surface of the lens system to the image plane. The total length and the total lens thickness, which is the distance from the most object-side surface to the most image-side surface of the lens system, are large, and there is a problem in terms of miniaturization. The optical system disclosed in Patent Document 2 has a configuration close to a symmetric type, and has achieved a wide angle with a half angle of view exceeding 50 degrees, but originally it is not so much intended for a large aperture. It seems that the F value is as large as F4 to F4.5, which is inadequate in terms of increasing the diameter. Although the optical system disclosed in Patent Document 3 has a small total lens length and a total lens thickness, since the back focus is short, the diameter of the lens close to the image plane is large and it cannot be said that the lens is sufficiently small. . The optical system disclosed in Patent Document 4 is improved in view angle, F value, and imaging performance, but has a configuration in which the characteristics of the retrofocus type remain strong, and is also reduced in size. There are still challenges.
The present invention has been made in view of the above-described circumstances. The half angle of view is a wide angle of about 35 to 43 degrees, the F value is a large aperture of about F2.8, the total lens length, the total lens thickness, and the lens diameter. An imaging lens that is small in size, sufficiently reduces various aberrations, and can obtain high performance having a resolving power corresponding to an image sensor with 12 to 24 million pixels. It is an object.

In order to achieve the above-described object, the imaging lens according to the present invention provides
An imaging lens composed of a plurality of lenses,
An air space between two adjacent lenses that are spaced apart from each other and that is sandwiched between the object side surface of the object side lens and the object side surface of the image side lens is referred to as an air lens. And the object side surface of the air lens, the object side surface of the image side lens is the image side surface of the air lens, and the shape of the air lens is defined,
Among the imaging lenses, the air lens having a negative power is only two lenses , an air lens located closest to the object side and an air lens located closest to the image side, and both are biconvex ,
Let L be the distance from the most object-side surface of the imaging lens to the image plane when focused on an object at infinity, and f be the focal length of the entire imaging lens system when focused on an object at infinity. ,
Conditional expression:
[7] 1.4 <L / f <2.0
It is characterized by satisfying.

  According to the present invention, the half angle of view is as wide as 35 to 43 degrees, the F value is as large as F2.8, and the entire lens length, the total lens thickness, and the lens diameter are small. It is possible to provide an imaging lens that can sufficiently reduce aberrations and obtain high performance having a resolving power corresponding to an image sensor with 12 to 24 million pixels.

That is, according to the imaging lens according to the present invention,
An imaging lens composed of a plurality of lenses ,
Referred two lenses next contact and are spaced apart from each other, the air gap sandwiched between the object side surface of the image-side surface and image-side lens of the object side lens which faces each other with the air lens, the image side surface of the object side lens And the object side surface of the air lens, the object side surface of the image side lens is the image side surface of the air lens, and the shape of the air lens is defined,
Among the imaging lenses, the air lens having a negative power is only two lenses , an air lens located closest to the object side and an air lens located closest to the image side, and both are biconvex ,
Let L be the distance from the most object-side surface of the imaging lens to the image plane when focused on an object at infinity, and f be the focal length of the entire imaging lens system when focused on an object at infinity. ,
Conditional expression:
[7] 1.4 <L / f <2.0
It is characterized by satisfying .

It is a longitudinal cross-sectional view along the optical axis which shows the structure of the optical system of the imaging lens in Example 1 which concerns on the 1st Embodiment of this invention. FIG. 4 is an aberration curve diagram showing various aberrations of spherical aberration, astigmatism, distortion and coma with respect to d-line and g-line in the imaging lens according to Example 1 of the present invention shown in FIG. 1. It is a longitudinal cross-sectional view along the optical axis which shows the structure of the optical system of the imaging lens in Example 2 which concerns on the 2nd Embodiment of this invention. FIG. 4 is an aberration curve diagram showing various aberrations of spherical aberration, astigmatism, distortion aberration and coma aberration for the d-line and g-line in the imaging lens according to Example 2 of the present invention shown in FIG. 3. It is a longitudinal cross-sectional view along the optical axis which shows the structure of the optical system of the imaging lens in Example 3 which concerns on the 3rd Embodiment of this invention. FIG. 6 is an aberration curve diagram showing various aberrations of spherical aberration, astigmatism, distortion, and coma aberration for the d-line and the g-line in the imaging lens according to Example 3 of the present invention shown in FIG. 5. It is a longitudinal cross-sectional view along the optical axis which shows the structure of the optical system of the imaging lens in Example 4 which concerns on the 4th Embodiment of this invention. FIG. 10 is an aberration curve diagram showing various aberrations of spherical aberration, astigmatism, distortion and coma aberration for the d-line and g-line in the imaging lens according to Example 4 of the present invention shown in FIG. 7. It is a longitudinal cross-sectional view along the optical axis which shows the structure of the optical system of the imaging lens in Example 5 which concerns on the 5th Embodiment of this invention. FIG. 10 is an aberration curve diagram showing various aberrations of spherical aberration, astigmatism, distortion and coma aberration with respect to d line and g line in the imaging lens according to Example 5 of the present invention shown in FIG. 9. It is a longitudinal cross-sectional view along the optical axis which shows the structure of the optical system of the imaging lens in Example 6 which concerns on the 6th Embodiment of this invention. FIG. 12 is an aberration curve diagram showing various aberrations of spherical aberration, astigmatism, distortion, and coma aberration for the d-line and g-line in the imaging lens according to Example 6 of the present invention shown in FIG. 11. It is a longitudinal cross-sectional view along the optical axis which shows the structure of the optical system of the imaging lens in Example 7 which concerns on the 7th Embodiment of this invention. FIG. 14 is an aberration curve diagram showing various aberrations of spherical aberration, astigmatism, distortion and coma with respect to d-line and g-line in the imaging lens according to Example 7 shown in FIG. 13. It is a longitudinal cross-sectional view along the optical axis which shows the structure of the optical system of the imaging lens in Example 8 which concerns on the 8th Embodiment of this invention. FIG. 16 is an aberration curve diagram showing various aberrations of spherical aberration, astigmatism, distortion and coma aberration for the d line and g line in the imaging lens according to Example 8 shown in FIG. 15. It is a longitudinal cross-sectional view along the optical axis which shows the structure of the optical system of the imaging lens in Example 9 which concerns on the 9th Embodiment of this invention. FIG. 18 is an aberration curve diagram showing various aberrations of spherical aberration, astigmatism, distortion and coma aberration for the d-line and g-line in the imaging lens according to Example 9 shown in FIG. 17. It is a longitudinal cross-sectional view along the optical axis which shows the structure of the optical system of the imaging lens in Example 10 which concerns on the 10th Embodiment of this invention. FIG. 20 is an aberration curve diagram showing various aberrations of spherical aberration, astigmatism, distortion, and coma aberration for d line and g line in the imaging lens according to Example 10 of the present invention shown in FIG. 19. It is the perspective view seen from the front side which shows typically the external appearance structure of the digital camera as an imaging device which concerns on the 11th Embodiment of this invention, ie, the object side which is a to-be-photographed object, (a) of this invention. The imaging lens constructed using the imaging lens according to the eleventh embodiment is retracted in the body of the digital camera, and (b) shows the imaging lens protruding from the body of the digital camera. Each is shown. It is the perspective view seen from the back side which shows the external appearance structure of the digital camera of FIG. 21, ie, a photographer side. It is a block diagram which shows typically the function structure of the digital camera of FIG. 21 and FIG.

Hereinafter, based on the first to tenth embodiments of the present invention, an imaging lens, an imaging device, and an information device according to the present invention will be described in detail with reference to the drawings. Before describing specific numerical examples, first, a fundamental embodiment of the present invention will be described.
The first embodiment of the present invention is an embodiment as an imaging lens constituting an optical system that forms an optical image of an object, but the second to tenth embodiments are also included. It is the same.
The imaging lens according to the first embodiment of the present invention is composed of a plurality of lenses, and is a single-focus imaging lens for imaging a subject image. The half angle of view is about 35 to 43 degrees and a wide angle. The F value is as large as about F2.8, and the lens is small in all of the total lens length, the total lens thickness, and the lens diameter, and various aberrations are sufficiently reduced, resulting in 12 million to 24 million pixels. This is an imaging lens that makes it possible to obtain high performance having a resolving power corresponding to the imaging element.
That is, the imaging lens according to the first embodiment of the present invention is
An imaging lens composed of a plurality of lenses ,
Referred two lenses next contact and are spaced apart from each other, the air gap sandwiched between the object side surface of the image-side surface and image-side lens of the object side lens which faces each other with the air lens, the image side surface of the object side lens And the object side surface of the air lens, the object side surface of the image side lens is the image side surface of the air lens, and the shape of the air lens is defined,
Among the imaging lenses, the air lens having a negative power is only two lenses , an air lens located closest to the object side and an air lens located closest to the image side, and both are biconvex ,
Let L be the distance from the most object-side surface of the imaging lens to the image plane when focused on an object at infinity, and f be the focal length of the entire imaging lens system when focused on an object at infinity. ,
Conditional expression:
[7] 1.4 <L / f <2.0
By satisfying the above, it is wide-angle, large-diameter, small in all lens length, total lens thickness, and lens diameter, sufficiently reducing various aberrations, and resolving power corresponding to a high-pixel imaging device. By getting high performance having
Wide angle, large aperture, small size in all lens length, total lens thickness, and lens diameter, sufficiently reducing various aberrations, and obtaining high performance with resolving power corresponding to high-pixel imaging devices I made it.
The present invention also provides:
An imaging lens composed of a plurality of lenses,
An air space between two adjacent lenses that are spaced apart from each other and that is sandwiched between the object side surface of the object side lens and the object side surface of the image side lens is referred to as an air lens, and the image side surface of the object side lens. And the object side surface of the air lens, the object side surface of the image side lens is the image side surface of the air lens, and the shape of the air lens is defined,
Among the imaging lenses, the air lens located closest to the object side and the air lens located closest to the image side are both biconvex,
The imaging lens, in order from the object side to the image side, a front lens group having a positive refractive power, a stop, and a rear lens group having a positive refractive power are disposed.
The air lens located closest to the object side is disposed in the front lens group, and the air lens located closest to the image side is disposed in the rear lens group;
Assuming that the maximum image height is Y ′, the focal length of the entire imaging lens system in the state of focusing on an object at infinity is f, and the incident angle of the principal ray reaching the maximum image height to the image plane is θP _max .
Conditional expression:
[5] 0.7 <Y ′ / f <0.95
[6] 0.6 <tan (θP _max ) <0.95
You may comprise so that it may satisfy.

The imaging lens according to the first embodiment of the present invention described above is a substantially symmetric wide-angle lens, and has a total lens length, a total lens thickness, and a lens according to an unprecedented appropriate lens configuration and power arrangement. Miniaturization can be achieved in all diameters.
That is, in the imaging lens according to the first embodiment of the present invention, the air lens located closest to the object side and the air lens located closest to the image side in the imaging lens are both biconvex. Configure.
Here, the air space portion where the image side surface of the object side lens of the two lenses arranged adjacent to each other and the object side surface of the image side lens face each other is called an air lens, and the image side surface of the object side lens is the air lens. The shape of the air lens is defined with the object side surface of the lens and the object side surface of the image side lens as the image side surface of the air lens.
First of all, the above-mentioned imaging lens as a whole is based on a nearly symmetrical power arrangement in which a positive refractive power is arranged in the middle of the lens system and a negative refractive power is arranged on both sides of the lens system. It is easy to correct. For this reason, both the air lens located closest to the object side and the air lens located closest to the image side must be configured to have negative refractive power. Furthermore, by making these two air lenses both biconvex, various aberrations can be corrected at a higher level. In other words, the object side surface of the air lens located closest to the object side, the image side surface of the air lens located closest to the object side, the object side surface of the air lens located closest to the image side, and the image side surface of the air lens located closest to the image side These four surfaces are all concave.

Of the configurations described above, making the object side surface of the air lens located closest to the object side concave has the effect of appropriately controlling spherical aberration and facilitating correction of astigmatism. Making the image side surface of the air lens located at the concave surface control the exit pupil distance, making it possible to set the incident angle to the image surface of the principal ray at the peripheral image height to an appropriate state, and mainly There is an effect of facilitating correction of coma and distortion.
Moreover, making the image side surface of the air lens located closest to the object side concave has the effect of facilitating correction of coma aberration of the lower ray while realizing a reduction in the diameter of the lens closest to the object side of the lens system, Making the object side of the air lens located closest to the image side concave has the effect of reducing the diameter of the lens closest to the image and facilitating correction of coma aberration of the upper ray. This is advantageous for achieving both performance.
As described above, the configuration of each part of such an imaging lens is optimized for the purpose, and produces an effect that is not possible in the past, widening, large aperture, miniaturization and high performance. Can also be realized.

In addition, the imaging lens described above is
The air lens having negative power in the imaging lens is composed of only two air lenses, the air lens located closest to the object side and the air lens located closest to the image side. It may be optimized to provide a higher performance imaging lens.
The imaging lens described above is
The radius of curvature of the object side surface of the air lens located closest to the object side is r ₁ o, the radius of curvature of the image side surface of the air lens located closest to the object side is r ₂ o, and the object of the air lens located closest to the image side Let r ₁ i be the radius of curvature of the side surface, and r ₂ i be the radius of curvature of the image side surface of the air lens located closest to the image side.
Conditional expression:
[1] −0.6 <(r ₁ o + r ₂ o) / (r ₁ o−r ₂ o) <0.3
[2] −0.2 <(r ₁ i + r _2i ) / (r ₁ i−r ₂ i) <0.5
To satisfy
A compact and high-performance imaging lens in which the shape of the air lens is optimized and spherical aberration, astigmatism, coma and the like are corrected more favorably may be used.

That is, it is possible to obtain higher imaging performance by satisfying the conditional expression [1] and conditional expression [2] described above for the shapes of the air lenses on the object side and the image side.
If the conditional expression [1] is −0.6 or less, the refractive power of the object side surface of the air lens located closest to the object side becomes relatively strong, and spherical aberration is likely to occur greatly in the under direction. The field curvature is not preferable because the intermediate image height tends to be greatly displaced to the minus side. On the other hand, if the conditional expression [1] is 0.3 or more, the refractive power of the image side surface of the air lens located closest to the object side becomes relatively strong, and spherical aberration tends to occur greatly in the over direction. Or the curvature of field tends to be greatly tilted to the plus side at the periphery, and coma tends to remain undesirably.
If the conditional expression [2] is −0.2 or less, the refractive power of the object side surface of the air lens located closest to the image side becomes relatively strong, and spherical aberration is likely to occur greatly in the over direction. Or inward coma tends to remain, which is not preferable. On the other hand, if conditional expression [2] is 0.5 or more, the refractive power of the image side surface of the air lens located closest to the image side becomes relatively strong, and astigmatism is likely to occur, It is not preferable because coma aberration in the peripheral portion tends to be disturbed. Further, by satisfying the conditional expression [2], the exit pupil position is controlled, and the effect of making the incident angle of the principal ray on the image plane appropriate for the peripheral image height on the image plane can be obtained.

The imaging lens described above also has
The imaging lens, in order from the object side to the image side, a front lens group having a positive refractive power, a stop, and a rear lens group having a positive refractive power are disposed.
The air lens located closest to the object side is disposed in the front lens group, and the air lens located closest to the image side is disposed in the rear lens group.
By making both the refractive power before and after the aperture positive, distortion aberration, coma aberration, lateral chromatic aberration, etc. can be corrected well, and a compact and high-performance imaging lens may be obtained.
In other words, the imaging lens is configured by sequentially arranging, from the object side, a front lens group having a positive refractive power, a diaphragm, and a rear lens group having a positive refractive power, and is located closest to the object side. The lens is included in the front lens group, and the air lens located closest to the image side is included in the rear lens group.
By balancing the negative refractive power of the air lens at both ends of the lens system and at the same time making the refractive power before and after the aperture both positive, a nearly symmetrical power arrangement becomes more reliable, coma and distortion , And the lateral chromatic aberration can be corrected more satisfactorily.

The imaging lens described above further includes
The front lens group and the rear lens group are both composed of 3 or more and 4 or less lenses, respectively.
Each group was composed of sufficient number, and more favorably correct various aberrations, have to desirable to high-performance imaging lens in small size.
Since the air lens located closest to the object side and the air lens located closest to the image side are both biconvex, they have a relatively strong negative refractive power, and the entire lens system is positive as an imaging lens. In order to have a focal length, it is necessary to arrange a strong positive refractive power before and after the stop. In order to establish such a power arrangement without difficulty and to achieve good aberration correction, it is preferable to provide a positive lens before and after the stop, apart from the lens constituting the air lens. Since two lenses are required to construct the air lens, the result is that the front lens group and the rear lens group have a configuration of 3 or more and 4 or less, respectively.

The imaging lens described above is further
Both the most image side surface of the front lens group and the most object side surface of the rear lens group are convex surfaces,
Friendly symmetry of opposite faces across the aperture, and further favorably correct coma, have to desirable to high-performance imaging lens in small size.
That is, both the most image side surface of the front lens unit and the most object side surface of the rear lens unit, that is, the surface of both sides of the real lens (the lens having an entity that is not an air lens) sandwiching the stop (both convex on the stop side) ()) Convex surface. As described above, the above-mentioned imaging lens is based on a substantially symmetrical power arrangement, but the coma aberration is greatly reduced by following the substantially symmetrical power arrangement on the two surfaces facing each other across the diaphragm. It is possible to correct at a very high level.

More specifically, the imaging lens described above is
The radius of curvature of the most image side surface of the front lens group is r _1s , and the radius of curvature of the most object side surface of the rear lens group is r _2s .
Conditional expression:
[3] -0.2 <( _r1s + _r2s ) / ( _{r1s- r2s} ) <0.7
To satisfy
Friendly symmetry of opposite faces across the aperture, and further favorably correct coma, it is not more desirable to high-performance imaging lens in small size.

The imaging lens described above further includes
The focal length of the front lens group is f _F and the focal length of the rear lens group is f _R.
Conditional expression:
[4] 0.3 <f _F / f _R <2.5
To satisfy
Aperture optimizes refractive power ratio between the front and rear, distortion, and further favorably correct coma and lateral chromatic aberration, it is not more desirable to high-performance imaging lens in small size.
If conditional expression [4] is 0.3 or less, the refractive power on the front side of the stop becomes too strong, and distortion becomes easy to bend positively at the periphery, or inward coma occurs. This is not preferable because it tends to be easily generated, and chromatic aberration of magnification with a short wavelength tends to occur toward the inner side of the screen. On the other hand, if the conditional expression [4] is 2.5 or more, the refractive power on the rear side of the stop becomes relatively strong, and negative distortion is likely to occur, or outward coma is not generated. This is not preferable because it tends to occur or chromatic aberration of magnification with a short wavelength tends to occur toward the outside of the screen.

In addition, the imaging lens described above is
Assuming that the maximum image height is Y ′, the focal length of the entire imaging lens system in the state of focusing on an object at infinity is f, and the incident angle of the principal ray reaching the maximum image height to the image plane is θP _max .
Conditional expression:
[5] 0.7 <Y ′ / f <0.95
[6] 0.6 <tan (θP _max ) <0.95
To satisfy
Were both wide angle and miniaturization, yet good as a high-performance imaging lens.
The above-mentioned imaging lens is a wide-angle lens having a half angle of view of 35 degrees or more, and aims at miniaturization and high performance by appropriately controlling the incident angle of the principal ray reaching the maximum image height to the image plane. It is desirable that the above-mentioned conditional expressions [5] and [6] are satisfied.
That is, the conditional expression [5] regulates the angle of view of the imaging lens that best exhibits the effect of the present invention. Conditional expression [6] regulates the incident angle of the off-axis light beam on the image plane of the imaging lens that best exhibits the effect of the present invention.

And the imaging lens mentioned above is
Let L be the distance from the most object-side surface of the imaging lens to the image plane when focused on an object at infinity, and f be the focal length of the entire imaging lens system when focused on an object at infinity. ,
Conditional expression:
[7] 1.4 <L / f <2.0
To satisfy
The most effective overall length of the lens and the lens total thickness so as to raise the to optimize, also not good as a high-performance of the imaging lens.
In addition, the imaging lens described above is
Let D _{T be} the distance from the most object-side surface of the imaging lens to the most image-side surface of the imaging lens, and let f be the focal length of the entire imaging lens system when focused on an infinite object.
Conditional expression:
[8] 0.7 <D _T /f<1.2
To satisfy
The most effective is also not good as a high-performance of the imaging lens to optimize overall length of the lens and the lens total thickness of the so as to raise the.

That is, conditional expression [7] regulates the total lens length (the distance from the most object-side surface of the lens system to the image plane) of the imaging lens that best exhibits the effects of the present invention.
Conditional expression [8] regulates the total lens thickness (the distance from the most object-side surface to the most image-side surface of the lens system) of the imaging lens that best exhibits the effect of the present invention.
Further, the front lens group includes a negative lens having a concave surface facing the image side closest to the object side, a negative lens having a concave surface facing the object side adjacent to the image side, and the two lenses. A biconvex air lens may be formed between the two.
In the rear lens group, either a meniscus single lens having a concave surface facing the object side or a meniscus cemented lens as a whole with the concave surface facing the object side is arranged on the most image side, and the object A negative lens having a concave surface facing the image side may be disposed adjacent to the image side, and a biconvex air lens may be formed between the two lenses.
Assuming the above-described configuration, the focal length of a negative lens that is disposed closest to the object side of the front lens group and has a concave surface facing the image side is f _FF , and is positioned closest to the image side of the rear lens group. The following conditional expression [9] is satisfied, where f _R is the focal length of a meniscus single lens with a concave surface facing the object side or a meniscus cemented lens as a whole with the concave surface facing the object side: Is desirable.

[9] -0.2 <f _FF / f _RR <0.5
The imaging lens of the present invention is small in size on the premise that the incident angle of the chief ray reaching the maximum image height to the image plane is about the same as the half angle of view (both about 35 degrees to 40 degrees to 43 degrees). The aim is to improve performance and performance. When the conditional expression [9] is −0.2 or less, the retrofocus characteristic becomes strong, the principal point moves to the image side, and it becomes difficult to shorten the entire lens length. In addition, the exit pupil moves toward the object side, and the rear lens group is easily increased in diameter. On the other hand, if the conditional expression [9] is 0.5 or more, the telephoto characteristics become strong, the principal point moves to the object side, the total lens length becomes too short, and the degree of freedom in correcting various aberrations is limited. The manufacturing error sensitivity is increased, which is not preferable. In addition, the exit pupil moves toward the image side, and the incident angle of the principal ray on the image plane at the peripheral image height tends to increase.
For better aberration correction, the following conditional expression [9 ′] should be satisfied.
[9 ′] 0.0 <f _FF / f _RR <0.4
For better aberration correction, it is desirable to provide aspheric surfaces for both the lens disposed closest to the object side and the lens disposed closest to the image side. Doing so has a great effect on correction of astigmatism, coma and distortion.

The imaging lens according to the present invention is preferably configured as a single focus lens, and focusing may be performed by moving the entire imaging lens.
In the eleventh embodiment of the present invention, the imaging lens according to the above-described first embodiment (including second to tenth embodiments described later) is used as an imaging optical system. It is an imaging device constituted using.
That is, the imaging lens described above constitutes an imaging optical system in an imaging apparatus such as a so-called digital camera,
The half angle of view is a wide angle of about 35 to 43 degrees, the F value is about F2.8 and a large aperture. Te, the number of pixels is set to 12 million ～2,400 megapixel high-performance imaging lens of the imaging optical system having a resolution corresponding to an imaging device, yet good as compact and high quality imaging apparatus.
The imaging lens described above constitutes an imaging optical system in an information device such as a portable information terminal device having an imaging function,
Similarly using a high performance imaging lens in small size as an imaging optical system of the imaging function portion, yet good as an information device quality is obtained in a small size.

Next, specific examples based on the above-described embodiment of the present invention will be described in detail. Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Example 7, Example 8, Example 9, Example 9 and Example 10 described below are the first of the present invention. Embodiment, 2nd Embodiment, 3rd Embodiment, 4th Embodiment, 5th Embodiment, 6th Embodiment, 7th Embodiment, 8th Embodiment The ninth embodiment is an example of a specific configuration based on specific numerical examples of the imaging lens according to the tenth embodiment, and the eleventh embodiment is an example of the first to the second embodiments. It is embodiment of the imaging device or information apparatus which used the imaging lens shown in Example 10 as an imaging optical system.
FIGS. 1 and 2 are for explaining an imaging lens in Example 1 according to the first embodiment of the present invention, and FIGS. 3 and 4 illustrate the second embodiment of the present invention. FIG. 5 and FIG. 6 are for explaining the imaging lens in Example 3 according to the third embodiment of the present invention. FIGS. 7 and 8 are for explaining the imaging lens in Example 4 according to the fourth embodiment of the present invention, and FIGS. 9 and 10 illustrate the fifth embodiment of the present invention. FIG. 11 and FIG. 12 are for explaining the imaging lens in Example 6 according to the sixth embodiment of the present invention. FIG. 13 and FIG. 14 show the seventh embodiment of the present invention. FIG. 15 and FIG. 16 are for explaining the imaging lens in Example 8 according to the eighth embodiment of the present invention. FIGS. 17 and 18 are for explaining the imaging lens in Example 9 according to the ninth embodiment of the present invention, and FIGS. 19 and 20 illustrate the tenth embodiment of the present invention. It is for demonstrating the imaging lens in Example 10 which concerns on this form.

In all of Examples 1 to 10, the maximum image height is 14.2 mm.
In the imaging lenses of Examples 1 to 10, the parallel flat plate disposed on the image side of the rear lens group includes various filters such as an optical low-pass filter and an infrared cut filter, a CMOS sensor, and the like. The cover glass (seal glass) of the light receiving element is assumed. The parallel plate is disposed so that the image side surface is located at a position of about 0.5 mm from the image formation surface to the object side. However, the parallel plate is not limited to this and may be divided into a plurality of sheets.
In addition, the glass material of the optical glass used in each Example of these Examples 1-10 is the optical of the product of HOYA Corporation (HOYA), Ohara Corporation (OHARA), and Sumita Optical Glass Corporation (SUMITA). The glass type is shown.
Aberrations in Examples 1 to 10 are corrected at a high level, and spherical aberration and axial chromatic aberration are very small. Astigmatism, field curvature, and lateral chromatic aberration are also sufficiently small, and coma aberration and disturbance of the color difference are well suppressed to the outermost periphery. Further, the distortion aberration is 2.0% or less in absolute value. By forming the imaging lens as in the present invention, the half angle of view is as wide as 35 to 43 degrees, the F value is as large as F2.8, and the total lens length, total lens thickness and It is clear from Examples 1 to 10 that it is possible to achieve miniaturization in all lens diameters and to ensure very good image performance.

The meanings of symbols common to the first to tenth embodiments are as follows.
f: Focal length of the entire optical system F: F value (F number)
ω: Half field angle R: Radius of curvature (Paraxial radius of curvature for aspheric surfaces)
D: surface interval Nd: refractive index [nu] d: Abbe number P _{g, F:} partial dispersion ratio _{P g, F = (n g} -n F) / (n F -n C)
In Examples 1 to 10, some lens surfaces are aspherical. In order to form an aspherical surface, each lens surface is directly aspherical like a so-called molded aspherical lens, and a resin that forms an aspherical surface on the lens surface of a spherical lens like a so-called hybrid aspherical lens. There is a configuration in which an aspheric surface is obtained by laying a thin film, any of which may be used. In such an aspherical shape, the displacement in the optical axis direction (that is, the amount of aspherical surface in the optical axis direction) X at the position of the height H from the optical axis with respect to the vertex of the surface is an aspherical cone. The constant is K, the fourth-order aspheric coefficient is A ₄ , the sixth-order aspheric coefficient is A ₆ , the eighth-order aspheric coefficient is A ₈ , the tenth-order aspheric coefficient is A ₁₀ , and the paraxial radius of curvature is It is defined by the following formula [10] where the reciprocal of R is C.

図１は、本発明の第１の実施の形態で且つ実施例１に係る結像レンズの光学系の光軸に沿う縦断面のレンズ構成を示している。
すなわち、本発明の実施例１に係る結像レンズの光学系は、図１に示すように、物体側から像面側に向かって、順次、第１レンズＬ１、第２レンズＬ２、第３レンズＬ３、第４レンズＬ４、絞りＡＤ、第５レンズＬ５、第６レンズＬ６、そして第７レンズＬ７を配置しており、第３レンズＬ３と第４レンズＬ４、並びに第５レンズＬ５と第６レンズＬ６は、それぞれ接合レンズを構成しており、いわゆる５群７枚構成としている。
レンズ群構成に着目すると、第１レンズＬ１〜第４レンズＬ４により正の屈折力を有する前側レンズ群としての第１レンズ群Ｇ１を構成し、そして第５レンズＬ５〜第７レンズＬ７により正の屈折力を有する後側レンズ群としての第２レンズ群Ｇ２を構成している。つまり、図１に示す結像レンズの光学系は、これら第１レンズ群Ｇ１、絞りＡＤ、そして第２レンズ群Ｇ２を、物体側から像面側に向かって、順次、配置した構成としている。

FIG. 1 shows a lens configuration of a longitudinal section along the optical axis of the optical system of the imaging lens according to the first embodiment of the present invention and Example 1.
That is, as shown in FIG. 1, the optical system of the imaging lens according to Example 1 of the present invention sequentially has a first lens L1, a second lens L2, and a third lens from the object side to the image surface side. L3, a fourth lens L4, an aperture stop AD, a fifth lens L5, a sixth lens L6, and a seventh lens L7 are arranged. The third lens L3 and the fourth lens L4, and the fifth lens L5 and the sixth lens. L6 respectively constitutes a cemented lens, and has a so-called five-group seven-lens configuration.
Focusing on the lens group configuration, the first lens L1 to the fourth lens L4 constitute a first lens group G1 as a front lens group having a positive refractive power, and the fifth lens L5 to the seventh lens L7 are positive. A second lens group G2 is configured as a rear lens group having refractive power. That is, the optical system of the imaging lens shown in FIG. 1 has a configuration in which the first lens group G1, the stop AD, and the second lens group G2 are sequentially arranged from the object side to the image plane side.

Specifically, the first lens group G1 as the front lens group is formed with an aspheric surface on the image side sequentially from the object side to the image side, and a concave surface having a larger curvature than the object-side surface. A first lens L1 composed of a negative lens having a biconcave shape, a second lens L2 composed of a negative lens having a negative meniscus shape having a concave surface facing the object side, and a negative having a negative meniscus shape having a convex surface facing the object side. A third lens L3 made of a lens, and a fourth lens L4 made of a positive lens having a biconvex shape with a convex surface having a larger curvature than the image surface side on the object side are arranged, and the first lens group G1 is positive. The refracting power is shown. Note that the two lenses, the third lens L3 and the fourth lens L4, are closely bonded to each other and integrally joined to form a cemented lens composed of two lenses.
A stop AD is disposed between the first lens group G1 as the front lens group and the second lens group G2 as the rear lens group.
The second lens group G2 as the rear lens group is a fifth lens including a positive lens having a biconvex shape with a convex surface having a larger curvature than the object side surface facing the image side sequentially from the object side to the image side. A lens L5, a sixth lens L6 composed of a negative lens having a biconcave shape with a concave surface having a larger curvature than the image side surface facing the object side, an aspherical surface facing the concave surface on the object side and an image side A negative meniscus seventh lens L7 having a convex shape on the image side is disposed, and the second lens group G2 is configured to exhibit positive refractive power. Note that the two lenses of the fifth lens L5 and the sixth lens L6 are closely bonded to each other and are integrally joined to form a cemented lens composed of two lenses.

An air lens having a biconvex shape is formed between the first lens L1 and the second lens L2 in the first lens group G1, which is the front lens group. In addition, an air lens having a biconvex shape is formed between the sixth lens L6 and the seventh lens L7 in the second lens group G2, which is the rear lens group.
Further, various filters such as an optical low-pass filter and an infrared cut filter and a cover glass (seal glass) of a light receiving element are equivalently provided behind these first lens group G1 and second lens group G2, that is, on the image side. A filter glass FG shown as a parallel plate is disposed.
As in the so-called digital still camera, in an imaging optical system using a solid-state imaging device such as a CCD (charge coupled device) sensor or a CMOS (complementary metal oxide semiconductor) sensor, a back insertion glass, a low-pass filter, an infrared cut At least one of glass and a cover glass for protecting the light receiving surface of the solid-state image sensor is inserted. In this embodiment, as the above-described filter glass FG, one parallel plate is equivalently used. As shown. In addition, in Example 2 to Example 10, the filter glass FG is equivalently shown as one parallel flat plate. However, similar to the filter glass FG in this example, the back insertion glass, the low-pass filter, and the infrared cut It represents at least one of glass and cover glass.

The first lens group G1, the aperture stop AD, and the second lens group G2 are supported almost integrally by an appropriate support frame or the like at least during use. Perform focusing.
FIG. 1 also shows the surface number of each optical surface in the optical system of the imaging lens. Note that each reference symbol shown in FIG. 1 is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference symbol. Therefore, FIG. 3, FIG. 5, FIG. 9, 11, 13, 15, 17, 19, and the like are not necessarily in a common configuration with the corresponding embodiments.
In Example 1, the focal length f, the open F value F, and the half angle of view ω [degrees] of the entire optical system are f = 18.32, F = 2.85, and ω = 38.2. , Radius of curvature of optical surface (paraxial radius of curvature for an aspheric surface) R, distance between adjacent optical surfaces, refractive index Nd, Abbe number νd, and lens material, etc. Is as shown in Table 1 below.

In Table 1, the lens surface with the surface number indicated by adding “* (asterisk)” to the surface number is an aspherical surface. In addition, the name of the manufacturer is abbreviated as HOYA (HOYA Corporation) before the glass type name of the glass material of the optical glass lens. The same applies to the other embodiments.
That is, in Table 1, the optical surfaces of the second surface and the thirteenth surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation [10] are as follows.
Aspherical parameter second surface K = 7.001177
A ₄ = 1.70754 × 10 ⁻⁴
A ₆ = −341940 × 10 ⁻⁷
A ₈ = 1.25705 × 10 ⁻⁷
A ₁₀ = −2.19437 × 10 ⁻⁹
13th surface K = -2.61685
A ₄ = 1.226506 × 10 ⁻⁴
A ₆ = 3.77944 × 10 ⁻⁶
A ₈ = 8.667908 × 10 ⁻⁸
A ₁₀ = −3.66673 × 10 ⁻¹⁰
In this case, the values corresponding to the conditional expressions [1] to [9] are as follows, and satisfy the conditional expressions [1] to [9], respectively.

[1] (r _1o + r _2o ) / (r _1o −r _2o ) = 0.020
[2] (r _1i + r _2i ) / (r _1i −r _2i ) = 0.081
[3] (r _1s + r _2s ) / (r _1s −r _2s ) = 0.223
[4] _{f F} / f R = 0.733
[5] Y '/ f = 0.775
[6] tan (θP _max ) = 0.663
[7] L / f = 1.632
[8] D _T /f=0.888
[9] f _FF / f _RR = 0.168
FIG. 2 shows aberration curves of various aberrations at the d-line and g-line of the imaging lens according to Example 1, that is, spherical aberration, astigmatism, distortion aberration, and coma aberration. In the aberration curve diagram of FIG. 2, the broken line in spherical aberration represents the sine condition, the solid line in astigmatism represents sagittal, and the broken line represents meridional. Further, d and g in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent d-line and g-line, respectively. The same applies to the aberration curve diagrams according to other examples.

FIG. 3 shows a lens configuration of a longitudinal section along the optical axis of the optical system of the imaging lens according to Example 2 of the second embodiment of the present invention.
That is, as shown in FIG. 3, the optical system of the imaging lens according to Example 2 of the present invention sequentially has a first lens L1, a second lens L2, and a third lens from the object side to the image surface side. L3, stop AD, fourth lens L4, fifth lens L5, and sixth lens L6 are disposed. The fourth lens L4 and the fifth lens L5 constitute a cemented lens, so-called five elements in six groups. It is configured.
Focusing on the lens group configuration, the first lens L1 to the third lens L3 constitute a first lens group G1 as a front lens group having a positive refractive power, and the fourth lens L4 to the sixth lens L6 are positive. A second lens group G2 is configured as a rear lens group having refractive power. That is, the optical system of the imaging lens shown in FIG. 3 has a configuration in which the first lens group G1, the stop AD, and the second lens group G2 are sequentially arranged from the object side to the image plane side.

Specifically, the first lens group G1 as the front lens group is formed with an aspheric surface on the image side sequentially from the object side to the image side, and a concave surface having a larger curvature than the object side surface is directed. A first lens L1 made of a negative lens having a biconcave shape, a second lens L2 made of a negative lens having a negative meniscus shape with a concave surface facing the object side, and a convex surface having a curvature larger than that of the image side surface on the object side The first lens group G1 is configured to exhibit a positive refractive power by disposing a third lens L3 made of a positive lens having a biconvex shape facing the first lens group.
A stop AD is disposed between the first lens group G1 as the front lens group and the second lens group G2 as the rear lens group.
The second lens group G2 as the rear lens group is a fourth lens composed of a positive lens having a biconvex shape with a convex surface having a larger curvature than the object side surface sequentially directed from the object side to the image side. A lens L4, a fifth lens L5 composed of a negative lens having a biconcave shape with a concave surface having a curvature larger than the surface of the image surface facing the object side, a concave surface facing the object side, and an aspheric surface facing the image side A negative meniscus sixth lens L6 having a convex shape on the image side is disposed, and the second lens group G2 is configured to exhibit a positive refractive power. Note that the two lenses, the fourth lens L4 and the fifth lens L5, are closely bonded to each other and are integrally joined to form a cemented lens composed of two lenses.

An air lens having a biconvex shape is formed between the first lens L1 and the second lens L2 in the first lens group G1, which is the front lens group. In addition, an air lens having a biconvex shape is formed between the fifth lens L5 and the sixth lens L6 in the second lens group G2, which is the rear lens group.
Further, various filters such as an optical low-pass filter and an infrared cut filter and a cover glass (seal glass) of a light receiving element are equivalently provided behind these first lens group G1 and second lens group G2, that is, on the image side. A filter glass FG shown as a parallel plate is disposed.
As in the so-called digital still camera, in an imaging optical system using a solid-state imaging device such as a CCD (charge coupled device) sensor or a CMOS (complementary metal oxide semiconductor) sensor, a back insertion glass, a low-pass filter, an infrared cut At least one of glass and a cover glass for protecting the light receiving surface of the solid-state image sensor is inserted. In this embodiment, as the above-described filter glass FG, one parallel plate is equivalently used. As shown. In addition, although filter glass FG is equivalently shown as one parallel plate also in Example 1 and Examples 3 to 10, back insertion glass and low-pass filter are the same as filter glass FG in this example. In addition, at least one of infrared cut glass and cover glass is represented.

The first lens group G1, the aperture stop AD, and the second lens group G2 are supported almost integrally by an appropriate support frame or the like at least during use. Perform focusing.
FIG. 3 also shows the surface numbers of the optical surfaces in the optical system of the imaging lens. Note that each reference symbol shown in FIG. 3 is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference symbol. Therefore, FIG. 1, FIG. 5, FIG. 9, 11, 13, 15, 17, 19, and the like are not necessarily in a common configuration with the corresponding embodiments.
In Example 2, the focal length f, the open F value F, and the half angle of view ω [degrees] of the entire optical system are f = 18.34, F = 2.88, and ω = 38.2, respectively. Optical radius of curvature (paraxial radius of curvature for aspheric surfaces) R, surface spacing D of adjacent optical surfaces, refractive index Nd, Abbe number νd, lens material, etc. Is as shown in Table 2 below.

Also in Table 2, the lens surface with the surface number indicated by adding “*” to the surface number is an aspherical surface. In addition, the name of the manufacturer is abbreviated as HOYA (HOYA Corporation) or the like before the glass type name of the glass material of the optical glass lens. The same applies to the other embodiments.
That is, in Table 1, the optical surfaces of the second surface and the twelfth surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation [10] are as follows.

Aspherical parameter second surface K = 3.779018
A ₄ = 1.47147 × 10 ⁻⁴
A ₆ = −1.66166 × 10 ⁻⁶
A ₈ = 1.59220 × 10 ⁻⁷
A ₁₀ = −3.448523 × 10 ⁻⁹
12th surface K = -2.38795
A ₄ = 1.775179 × 10 ⁻⁴
A ₆ = 4.15425 × 10 ⁻⁶
A ₈ = 1.226254 × 10 ⁻⁷
A ₁₀ = −7.36910 × 10 ⁻¹⁰
In this case, the values corresponding to the conditional expressions [1] to [9] are as follows, and satisfy the conditional expressions [1] to [9], respectively.

[1] (r _1o + r _2o ) / (r _1o −r _2o ) = − 0.149
[2] (r _1i + r _2i ) / (r _1i −r _2i ) = 0.031
[3] (r _1s + r _2s ) / (r _1s −r _2s ) = 0.231
[4] f _F / f _R = 1.243
[5] Y ′ / f = 0.774
[6] tan (θP _max ) = 0.748
[7] L / f = 1.668
[8] D _T /f=0.886
[9] f _FF / f _RR = 0.095
FIG. 4 shows aberration curves of various aberrations in the d-line and g-line of the imaging lens according to Example 2, that is, spherical aberration, astigmatism, distortion aberration, and coma aberration. In the aberration curve diagram of FIG. 4, the broken line in spherical aberration represents the sine condition, the solid line in astigmatism represents sagittal, and the broken line represents meridional. Further, d and g in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent d-line and g-line, respectively. The same applies to the aberration curve diagrams according to other examples.

FIG. 5 shows a lens configuration of a longitudinal section along the optical axis of the optical system of the imaging lens according to Example 3 of the third embodiment of the present invention.
That is, the optical system of the imaging lens according to Example 3 of the present invention, as shown in FIG. L3, a fourth lens L4, an aperture stop AD, a fifth lens L5, a sixth lens L6, and a seventh lens L7 are arranged. The third lens L3 and the fourth lens L4, and the fifth lens L5 and the sixth lens. L6 respectively constitutes a cemented lens, and has a so-called five-group seven-lens configuration.
Focusing on the lens group configuration, the first lens L1 to the fourth lens L4 constitute a first lens group G1 as a front lens group having a positive refractive power, and the fifth lens L5 to the seventh lens L7 are positive. A second lens group G2 is configured as a rear lens group having refractive power. That is, the optical system of the imaging lens shown in FIG. 5 has a configuration in which the first lens group G1, the stop AD, and the second lens group G2 are sequentially arranged from the object side to the image plane side.

In detail, the first lens group G1 as the front lens group has a negative meniscus having a concave surface formed with an aspheric surface on the image side and a concave shape on the image side sequentially from the object side to the image side. A first lens L1 made of a negative lens having a shape, a second lens L2 made of a negative lens having a biconcave shape with a strong concave surface facing the object side, and a negative lens having a negative meniscus shape convex to the object side And a fourth lens L4 composed of a positive lens having a biconvex shape with a convex surface having a larger curvature than the image-side surface on the object side, and a positive lens as the first lens group G1. The refracting power is shown. Note that the two lenses, the third lens L3 and the fourth lens L4, are closely bonded to each other and integrally joined to form a cemented lens composed of two lenses.
A stop AD is disposed between the first lens group G1 as the front lens group and the second lens group G2 as the rear lens group.
The second lens group G2 as the rear lens group is a fifth lens including a positive lens having a biconvex shape with a convex surface having a larger curvature than the object side surface facing the image side sequentially from the object side to the image side. A lens L5, a sixth lens L6 composed of a negative lens having a biconcave shape with a concave surface having a larger curvature than the image side surface facing the object side, an aspherical surface facing the concave surface on the object side and an image side A seventh lens L7 having a negative meniscus shape that is convex on the image side is disposed, and the second lens group G2 is configured to exhibit positive refractive power. Note that the two lenses of the fifth lens L5 and the sixth lens L6 are closely bonded to each other and are integrally joined to form a cemented lens composed of two lenses.

An air lens having a biconvex shape is formed between the first lens L1 and the second lens L2 in the first lens group G1, which is the front lens group. In addition, an air lens having a biconvex shape is formed between the sixth lens L6 and the seventh lens L7 in the second lens group G2, which is the rear lens group.
Further, various filters such as an optical low-pass filter and an infrared cut filter and a cover glass (seal glass) of a light receiving element are equivalently provided behind these first lens group G1 and second lens group G2, that is, on the image side. A filter glass FG shown as a parallel plate is disposed.
As in the so-called digital still camera, in an imaging optical system using a solid-state imaging device such as a CCD (charge coupled device) sensor or a CMOS (complementary metal oxide semiconductor) sensor, a back insertion glass, a low-pass filter, an infrared cut At least one of glass and a cover glass for protecting the light receiving surface of the solid-state image sensor is inserted. In this embodiment, as the above-described filter glass FG, one parallel plate is equivalently used. As shown. The filter glass FG is equivalently shown as one parallel flat plate in the first embodiment, the second embodiment, and the fourth to tenth embodiments. However, the back glass is inserted in the same manner as the filter glass FG in the present embodiment. It represents at least one of glass, low-pass filter, infrared cut glass, cover glass, and the like.

The first lens group G1, the aperture stop AD, and the second lens group G2 are supported almost integrally by an appropriate support frame or the like at least during use. Perform focusing.
FIG. 5 also shows the surface numbers of the optical surfaces in the optical system of the imaging lens. Note that each reference symbol shown in FIG. 5 is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference symbol. Therefore, FIG. 1, FIG. 3, FIG. 9, 11, 13, 15, 17, 19, and the like are not necessarily in a common configuration with the corresponding embodiments.
In Example 3, the focal length f, the open F value F, and the half angle of view ω [degrees] of the entire optical system are f = 18.30, F = 2.81, and ω = 38.2, respectively. , Radius of curvature of optical surface (paraxial radius of curvature for an aspheric surface) R, surface distance D of adjacent optical surfaces, refractive index Nd, Abbe number νd, and lens characteristics, etc. Is as shown in Table 3 below.

Also in Table 3, the lens surface with the surface number indicated by adding “*” to the surface number is an aspherical surface. In addition, the name of the manufacturer is abbreviated as HOYA (HOYA Corporation) or the like before the glass type name of the glass material of the optical glass lens. The same applies to the other embodiments.
That is, in Table 1, the optical surfaces of the second surface and the thirteenth surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation [10] are as follows.

Aspherical parameter second surface K = 3.80085,
A ₄ = 1.07069 × 10 ⁻⁴
A ₆ = −3.38949 × 10 ⁻⁶
A ₈ = 2.19205 × 10 ⁻⁷
A ₁₀ = −5.16455 × 10 ⁻⁹
13th surface K = -2.86234
A ₄ = 1.49055 × 10 ⁻⁴
A ₆ = 4.18583 × 10 ⁻⁶
A ₈ = 1.25343 × 10 ⁻⁷
A ₁₀ = −7.888154 × 10 ⁻¹⁰
In this case, the values corresponding to the conditional expressions [1] to [9] are as follows, and satisfy the conditional expressions [1] to [9], respectively.

[1] (r _1o + r _2o ) / (r _1o −r _2o ) = − 0.265
[2] (r _1i + r _2i ) / (r _1i −r _2i ) = 0.020
[3] (r _1s + r _2s ) / (r _1s −r _2s ) = 0.398
[4] _{f F} / f R = 1.203
[5] Y '/ f = 0.76
[6] tan (θP _max ) = 0.746
[7] L / f = 1.656
[8] D _T /f=0.855
[9] _{f FF} / f RR = 0.117
FIG. 6 shows aberration curves of various aberrations of the imaging lens according to Example 3, that is, spherical aberration, astigmatism, distortion and coma aberration. In the aberration curve diagram of FIG. 6, the broken line in spherical aberration represents the sine condition, the solid line in astigmatism represents sagittal, and the broken line represents meridional. Further, d and g in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent d-line and g-line, respectively. The same applies to the aberration curve diagrams according to other examples.

FIG. 7 shows a lens configuration of a longitudinal section along the optical axis of the optical system of the imaging lens according to Example 4 of the fourth embodiment of the present invention.
That is, as shown in FIG. 7, the optical system of the imaging lens according to Example 4 of the present invention sequentially has a first lens L1, a second lens L2, and a third lens from the object side to the image surface side. L3, a fourth lens L4, an aperture stop AD, a fifth lens L5, a sixth lens L6, and a seventh lens L7 are arranged. The third lens L3 and the fourth lens L4, and the fifth lens L5 and the sixth lens. L6 respectively constitutes a cemented lens, and has a so-called five-group seven-lens configuration.
Focusing on the lens group configuration, the first lens L1 to the fourth lens L4 constitute a first lens group G1 as a front lens group having a positive refractive power, and the fifth lens L5 to the seventh lens L7 are positive. A second lens group G2 is configured as a rear lens group having refractive power. That is, the optical system of the imaging lens shown in FIG. 7 has a configuration in which the first lens group G1, the diaphragm AD, and the second lens group G2 are sequentially arranged from the object side to the image plane side.
In detail, the first lens group G1 as the front lens group has a negative meniscus having a concave surface formed with an aspheric surface on the image side and a concave shape on the image side sequentially from the object side to the image side. A first lens L1 made of a negative lens having a shape, a second lens L2 made of a negative lens having a biconcave shape with a concave surface having a larger curvature than the image side surface facing the object side, and a convex shape on the object side A third lens L3 made of a negative lens having a negative meniscus shape, and a fourth lens L4 made of a positive lens having a biconvex shape with a convex surface having a larger curvature than the image side surface facing the object side, The first lens group G1 is configured to exhibit positive refractive power.

Note that the two lenses, the third lens L3 and the fourth lens L4, are closely bonded to each other and integrally joined to form a cemented lens composed of two lenses.
A stop AD is disposed between the first lens group G1 as the front lens group and the second lens group G2 as the rear lens group.
The second lens group G2 as the rear lens group is a fifth lens including a positive lens having a biconvex shape with a convex surface having a larger curvature than the object side surface facing the image side sequentially from the object side to the image side. A lens L5, a sixth lens L6 composed of a negative lens having a biconcave shape with a concave surface having a larger curvature than the image side surface facing the object side, an aspherical surface facing the concave surface on the object side and an image side A seventh lens L7 having a negative meniscus shape that is convex on the image side is disposed, and the second lens group G2 is configured to exhibit positive refractive power. Note that the two lenses of the fifth lens L5 and the sixth lens L6 are closely bonded to each other and are integrally joined to form a cemented lens composed of two lenses.

An air lens having a biconvex shape is formed between the first lens L1 and the second lens L2 in the first lens group G1, which is the front lens group. In addition, an air lens having a biconvex shape is formed between the sixth lens L6 and the seventh lens L7 in the second lens group G2, which is the rear lens group.
Further, various filters such as an optical low-pass filter and an infrared cut filter and a cover glass (seal glass) of a light receiving element are equivalently provided behind these first lens group G1 and second lens group G2, that is, on the image side. A filter glass FG shown as a parallel plate is disposed.
The first lens group G1, the aperture stop AD, and the second lens group G2 are supported almost integrally by an appropriate support frame or the like at least during use. Perform focusing.
FIG. 7 also shows the surface numbers of the optical surfaces in the optical system of the imaging lens. Note that each reference symbol shown in FIG. 7 is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference symbol. Therefore, FIG. 1, FIG. 3, FIG. 9, 11, 13, 15, 17, 19, and the like are not necessarily in a common configuration with the corresponding embodiments.
In Example 4, the focal length f, the open F value F, and the half angle of view ω [degrees] of the entire optical system are f = 18.32, F = 2.82, and ω = 38.2, respectively. , The optical surface curvature radius (paraxial curvature radius for an aspheric surface) R, the surface spacing D of adjacent optical surfaces, the refractive index Nd, the Abbe number νd, and the lens material, etc. Is as shown in Table 4 below.

Also in Table 4, the lens surface with the surface number indicated by adding “*” to the surface number is an aspherical surface. In addition, the name of the manufacturer is abbreviated as HOYA (HOYA Corporation) or the like before the glass type name of the glass material of the optical glass lens. The same applies to the other embodiments.
That is, in Table 4, the optical surfaces of the second surface and the thirteenth surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation [10] are as follows.

Aspherical parameter second surface K = 2.13028
A ₄ = 9.88636 × 10 ⁻⁵
A ₆ = −9.774939 × 10 ⁻⁸
A ₈ = 4.88682 × 10 ⁻⁸
A ₁₀ = −1.11860 × 10 ⁻¹⁰
13th surface K = −2.663168
A ₄ = 1.88683 × 10 ⁻⁴
A ₆ = 3.76968 × 10 ⁻⁶
A ₈ = 1.35267 × 10 ⁻⁷
A ₁₀ = −1.07927 × 10 ⁻⁹
In this case, the values corresponding to the conditional expressions [1] to [9] are as follows, and satisfy the conditional expressions [1] to [9], respectively.

[1] (r _1o + r _2o ) / (r _1o −r _2o ) = − 0.332
[2] (r _1i + r _2i ) / (r _1i −r _2i ) = − 0.047
[3] (r _1s + r _2s ) / (r _1s −r _2s ) = 0.440
[4] f _F / f _R = 1.059
[5] Y '/ f = 0.775
[6] tan (θP _max ) = 0.551
[7] L / f = 1.705
[8] D _T /f=0.877
[9] _{f FF} / f RR = 0.110
FIG. 8 shows aberration curves of various aberrations at the d-line and g-line of the imaging lens according to Example 4, that is, spherical aberration, astigmatism, distortion aberration, and coma aberration. In the aberration curve diagram of FIG. 8, the broken line in spherical aberration represents the sine condition, the solid line in astigmatism represents sagittal, and the broken line represents meridional. Further, d and g in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent d-line and g-line, respectively. The same applies to the aberration curve diagrams according to other examples.

FIG. 9 shows a lens configuration of a longitudinal section along the optical axis of the optical system of the imaging lens according to the fifth embodiment of the present invention and Example 5.
That is, as shown in FIG. 9, the optical system of the imaging lens according to Example 5 of the present invention sequentially includes a first lens L1, a second lens L2, and a third lens from the object side to the image surface side. L3, a fourth lens L4, an aperture stop AD, a fifth lens L5, a sixth lens L6, and a seventh lens L7 are arranged. The third lens L3 and the fourth lens L4, and the fifth lens L5 and the sixth lens. L6 respectively constitutes a cemented lens, and has a so-called five-group seven-lens configuration.
Focusing on the lens group configuration, the first lens L1 to the fourth lens L4 constitute a first lens group G1 as a front lens group having a positive refractive power, and the fifth lens L5 to the seventh lens L7 are positive. A second lens group G2 is configured as a rear lens group having refractive power. That is, the optical system of the imaging lens shown in FIG. 9 has a configuration in which the first lens group G1, the stop AD, and the second lens group G2 are sequentially arranged from the object side to the image plane side.
Specifically, the first lens group G1 as the front lens group is formed with an aspherical surface on the image side sequentially from the object side to the image side, and a concave surface having a larger curvature than the object side surface. A first lens L1 made of a negative lens having a biconcave shape, a second lens L2 made of a negative lens having a negative meniscus shape made concave on the object side, and a convex surface having a slightly larger curvature than the object side surface on the image side A first lens group G1 is arranged by arranging a third lens L3 made of a positive lens having a biconvex shape facing toward and a fourth lens L4 made of a negative lens having a negative meniscus shape convex on the image side. As shown in FIG.

Note that the two lenses, the third lens L3 and the fourth lens L4, are closely bonded to each other and integrally joined to form a cemented lens composed of two lenses.
A stop AD is disposed between the first lens group G1 as the front lens group and the second lens group G2 as the rear lens group.
The second lens group G2 as the rear lens group is a fifth lens including a positive lens having a biconvex shape with a convex surface having a larger curvature than the object side surface facing the image side sequentially from the object side to the image side. A lens L5, a sixth lens L6 composed of a negative lens having a biconcave shape with a concave surface having a larger curvature than the image side surface facing the object side, an aspherical surface facing the concave surface on the object side and an image side A seventh lens L7 having a negative meniscus shape that is convex on the image side is disposed, and the second lens group G2 is configured to exhibit positive refractive power. Note that the two lenses of the fifth lens L5 and the sixth lens L6 are closely bonded to each other and are integrally joined to form a cemented lens composed of two lenses.
An air lens having a biconvex shape is formed between the first lens L1 and the second lens L2 in the first lens group G1, which is the front lens group. In addition, an air lens having a biconvex shape is formed between the sixth lens L6 and the seventh lens L7 in the second lens group G2, which is the rear lens group.

Further, various filters such as an optical low-pass filter and an infrared cut filter and a cover glass (seal glass) of a light receiving element are equivalently provided behind these first lens group G1 and second lens group G2, that is, on the image side. A filter glass FG shown as a parallel plate is disposed.
The first lens group G1, the aperture stop AD, and the second lens group G2 are supported almost integrally by an appropriate support frame or the like at least during use. Perform focusing.
FIG. 9 also shows the surface numbers of the optical surfaces in the optical system of the imaging lens. In addition, in order to avoid complication of explanation due to an increase in the number of digits of the reference code, each reference code shown in FIG. 9 is used independently for each embodiment. Therefore, FIG. 1, FIG. 3, FIG. 7, 11, 13, 15, 17, 19, and the like are not necessarily in a common configuration with the corresponding embodiments.
In Example 5, the focal length f, the open F value F, and the half angle of view ω [degrees] of the entire optical system are f = 18.34, F = 2.86, and ω = 38.2, respectively. , Radius of curvature of optical surface (paraxial radius of curvature for an aspheric surface) R in each optical element in Example 5, optical distance between adjacent optical surfaces D, refractive index Nd, Abbe number νd, and optical characteristics such as lens material Is as shown in Table 5 below.

Also in Table 5, the lens surface having the surface number indicated by adding “*” to the surface number is an aspherical surface. In addition, the name of the manufacturer is abbreviated as HOYA (HOYA Corporation) or the like before the glass type name of the glass material of the optical glass lens. The same applies to the other embodiments.
That is, in Table 5, the optical surfaces of the second surface and the thirteenth surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation [10] are as follows.

Aspherical parameter second surface K = 3.442630
A ₄ = 1.82031 × 10 ⁻⁴
A ₆ = 2.887806 × 10 ⁻⁸
A ₈ = 1.09332 × 10 ⁻⁷
A ₁₀ = −1.19134 × 10 ⁻⁹
13th surface K = −2.05587
A ₄ = 1.76087 × 10 ⁻⁴
A ₆ = 3.99174 × 10 ⁻⁶
A ₈ = 1.04887 × 10 ⁻⁷
A ₁₀ = −4.666251 × 10 ⁻¹⁰
In this case, the values corresponding to the conditional expressions [1] to [9] are as follows, and satisfy the conditional expressions [1] to [9], respectively.

[1] (r _1o + r _2o ) / (r _1o −r _2o ) = − 0.110
[2] (r _1i + r _2i ) / (r _1i −r _2i ) = 0.021
[3] (r _1s + r _2s ) / (r _1s −r _2s ) = 0.316
[4] f _F / f _R = 1.097
[5] Y ′ / f = 0.774
[6] tan (θP _max ) = 0.748
[7] L / f = 1.659
[8] D _T /f=0.886
[9] _{f FF} / f RR = 0.136
In addition, FIG. 10 shows aberration curves of various aberrations in the d-line and g-line of the imaging lens according to Example 5, that is, spherical aberration, astigmatism, distortion aberration, and coma aberration. In the aberration curve diagram of FIG. 10, the broken line in spherical aberration represents the sine condition, the solid line in astigmatism represents sagittal, and the broken line represents meridional. Further, d and g in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent d-line and g-line, respectively. The same applies to the aberration curve diagrams according to other examples.

FIG. 11 shows a lens configuration of a longitudinal section along the optical axis of the optical system of the imaging lens according to the sixth embodiment of the present invention and Example 6.
That is, as shown in FIG. 11, the optical system of the imaging lens according to Example 6 of the present invention sequentially has a first lens L1, a second lens L2, and a third lens from the object side to the image surface side. L3, a fourth lens L4, an aperture stop AD, a fifth lens L5, a sixth lens L6, and a seventh lens L7 are arranged. The third lens L3 and the fourth lens L4, and the fifth lens L5 and the sixth lens. L6 respectively constitutes a cemented lens, and has a so-called five-group seven-lens configuration.
Focusing on the lens group configuration, the first lens L1 to the fourth lens L4 constitute a first lens group G1 as a front lens group having a positive refractive power, and the fifth lens L5 to the seventh lens L7 are positive. A second lens group G2 is configured as a rear lens group having refractive power. That is, the optical system of the imaging lens shown in FIG. 11 has a configuration in which the first lens group G1, the stop AD, and the second lens group G2 are sequentially arranged from the object side to the image plane side.

Specifically, the first lens group G1 serving as the front lens group has a negative meniscus having a convex surface on the object side and a concave surface formed with an aspheric surface on the image side sequentially from the object side to the image side. A first lens L1 formed of a negative lens having a shape, a second lens L2 formed of a negative lens having a negative meniscus shape concave on the object side, and a negative lens having a negative meniscus shape formed convex on the object side. A third lens L3, and a fourth lens L4 made of a positive lens having a biconvex shape with the convex surface having a larger curvature than the image side surface facing the object side, and is positive as the first lens group G1. It is configured to show refractive power. Note that the two lenses, the third lens L3 and the fourth lens L4, are closely bonded to each other and integrally joined to form a cemented lens composed of two lenses.
A stop AD is disposed between the first lens group G1 as the front lens group and the second lens group G2 as the rear lens group.
The second lens group G2 as the rear lens group is a fifth lens including a positive lens having a biconvex shape with a convex surface having a larger curvature than the object side surface facing the image side sequentially from the object side to the image side. A lens L5, a sixth lens L6 composed of a negative lens having a biconcave shape with a concave surface having a larger curvature than the image side surface facing the object side, an aspherical surface facing the concave surface on the object side and an image side A seventh lens L7 having a negative meniscus shape that is convex on the image side is disposed, and the second lens group G2 is configured to exhibit positive refractive power. Note that the two lenses of the fifth lens L5 and the sixth lens L6 are closely bonded to each other and are integrally joined to form a cemented lens composed of two lenses.

An air lens having a biconvex shape is formed between the first lens L1 and the second lens L2 in the first lens group G1, which is the front lens group. In addition, an air lens having a biconvex shape is formed between the sixth lens L6 and the seventh lens L7 in the second lens group G2, which is the rear lens group.
Further, various filters such as an optical low-pass filter and an infrared cut filter and a cover glass (seal glass) of a light receiving element are equivalently provided behind these first lens group G1 and second lens group G2, that is, on the image side. A filter glass FG shown as a parallel plate is disposed.
The first lens group G1, the aperture stop AD, and the second lens group G2 are supported almost integrally by an appropriate support frame or the like at least during use. Perform focusing.

FIG. 11 also shows the surface numbers of the optical surfaces in the optical system of the imaging lens. Note that each reference symbol shown in FIG. 11 is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference symbol. Therefore, FIG. 1, FIG. 3, FIG. 7, 9, 13, 15, 17, 19, and the like are not necessarily in a common configuration with the corresponding embodiments.
In Example 6, the focal length f, the open F value F, and the half angle of view ω [degrees] of the entire optical system are f = 15.72, F = 2.86, and ω = 42.4, respectively. , The curvature of the optical surface (paraxial curvature radius for an aspheric surface) R in each optical element in Example 6, the surface distance D between adjacent optical surfaces, the refractive index Nd, the Abbe number νd, and the optical characteristics such as the lens material Is as shown in Table 6 below.

Also in Table 6, the lens surface with the surface number indicated by adding “*” to the surface number is an aspherical surface. In addition, the name of the manufacturer is abbreviated as HOYA (HOYA Corporation) or the like before the glass type name of the glass material of the optical glass lens. The same applies to the other embodiments.
That is, in Table 6, the optical surfaces of the second surface and the thirteenth surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation [10] are as follows.

Aspherical parameter second surface K = 3.664665
A ₄ = 1.55190 × 10 ⁻⁴
A ₆ = 4.99693 × 10 ⁻⁶
A ₈ = −2.613329 × 10 ⁻⁷
A ₁₀ = 1.11640 × 10 ⁻⁸
13th surface K = -1.73578
A ₄ = 1.34058 × 10 ⁻⁴
A ₆ = 4.52767 × 10 ⁻⁶
A ₈ = 1.10405 × 10 ⁻⁷
A ₁₀ = −9.83332 × 10 ⁻¹⁰
In this case, the values corresponding to the conditional expressions [1] to [9] are as follows, and satisfy the conditional expressions [1] to [9], respectively.

[1] (r _1o + r _2o ) / (r _1o −r _2o ) = 0.122
[2] (r _1i + r _2i ) / (r _1i −r _2i ) = 0.249
[3] (r _1s + r _2s ) / (r _1s −r _2s ) = 0.050
[4] _{f F} / f R = 0.349
[5] Y '/ f = 0.903
[6] tan (θP _max ) = 0.899
[7] L / f = 1.765
[8] D _T /f=1.081
[9] _{f FF} / f RR = 0.360
FIG. 12 shows aberration curves of various aberrations at the d-line and g-line of the imaging lens according to Example 6, that is, spherical aberration, astigmatism, distortion aberration, and coma aberration. In the aberration curve diagram of FIG. 12, the broken line in spherical aberration represents the sine condition, the solid line in astigmatism represents sagittal, and the broken line represents meridional. Further, d and g in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent d-line and g-line, respectively. The same applies to the aberration curve diagrams according to other examples.

FIG. 13 shows a lens configuration of a longitudinal section along the optical axis of the optical system of the imaging lens according to the seventh embodiment of the present invention and Example 7.
That is, as shown in FIG. 13, the optical system of the imaging lens according to Example 7 of the present invention sequentially has a first lens L1, a second lens L2, and a third lens from the object side to the image surface side. L3, the fourth lens L4, the stop AD, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 are arranged. The third lens L3, the fourth lens L4, and the fifth lens L5. The sixth lens L6, the seventh lens L7, and the eighth lens L8 constitute a cemented lens, and have a so-called five-group eight-lens configuration.
Focusing on the lens group configuration, the first lens L1 to the fourth lens L4 constitute a first lens group G1 as a front lens group having a positive refractive power, and the fifth lens L5 to the eighth lens L8 are positive. A second lens group G2 is configured as a rear lens group having refractive power. That is, the optical system of the imaging lens shown in FIG. 13 has a configuration in which the first lens group G1, the stop AD, and the second lens group G2 are sequentially arranged from the object side to the image plane side.

Specifically, the first lens group G1 as the front lens group is formed with an aspherical surface on the image side sequentially from the object side to the image side, and a concave surface having a larger curvature than the surface on the object side. A first lens L1 made of a negative lens having a biconcave shape, a second lens L2 made of a negative lens having a negative meniscus shape concave on the object side, and a negative meniscus shape made convex on the object side. A first lens group G1 is arranged by arranging a third lens L3 made of a negative lens and a fourth lens L4 made of a positive lens having a biconvex shape with a convex surface having a larger curvature than the image side surface facing the object side. As shown in FIG. Note that the two lenses, the third lens L3 and the fourth lens L4, are closely bonded to each other and integrally joined to form a cemented lens composed of two lenses.
A stop AD is disposed between the first lens group G1 as the front lens group and the second lens group G2 as the rear lens group.
The second lens group G2 as the rear lens group is a fifth lens including a positive lens having a biconvex shape with a convex surface having a larger curvature than the object side surface facing the image side sequentially from the object side to the image side. It consists of a lens L5, a sixth lens L6 made of a negative lens having a concave surface with a curvature larger than the image side surface on the object side, and a negative lens having a negative meniscus shape made concave on the object side. A seventh lens L7 and a convex positive meniscus eighth lens L8 formed by forming an aspheric surface on the image side are arranged so that the second lens group G2 exhibits positive refractive power. doing. Note that the two lenses of the fifth lens L5 and the sixth lens L6 are closely bonded to each other and are integrally joined to form a cemented lens formed by joining the seventh lens L7 and the seventh lens L7. The two lenses of the eight lens L8 are also closely bonded to each other and integrally joined to form a cemented lens composed of two lenses.
An air lens having a biconvex shape is formed between the first lens L1 and the second lens L2 in the first lens group G1, which is the front lens group. In addition, an air lens having a biconvex shape is formed between the sixth lens L6 and the seventh lens L7 in the second lens group G2, which is the rear lens group.
Further, various filters such as an optical low-pass filter and an infrared cut filter and a cover glass (seal glass) of a light receiving element are equivalently provided behind these first lens group G1 and second lens group G2, that is, on the image side. A filter glass FG shown as a parallel plate is disposed.
The first lens group G1, the aperture stop AD, and the second lens group G2 are supported almost integrally by an appropriate support frame or the like at least during use. Perform focusing.

FIG. 13 also shows the surface numbers of the optical surfaces in the optical system of the imaging lens. Note that each reference symbol shown in FIG. 13 is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference symbol. Therefore, FIG. 1, FIG. 3, FIG. 7, 9, 11, 15, 17, 19, and the like are not necessarily in a common configuration with the corresponding embodiments.
In Example 7, the focal length f, the open F value F, and the half angle of view ω [degrees] of the entire optical system are f = 18.30, F = 2.56, and ω = 38.2, respectively. , The optical surface curvature radius (paraxial curvature radius for an aspheric surface) R, the surface spacing D of adjacent optical surfaces, the refractive index Nd, the Abbe number νd, and the lens material, etc. Is as shown in Table 7 below.

Also in Table 7, the lens surface with the surface number indicated by adding “*” to the surface number is an aspherical surface. In addition, the name of the manufacturer is abbreviated as HOYA (HOYA Corporation) or the like before the glass type name of the glass material of the optical glass lens. The same applies to the other embodiments.
That is, in Table 7, the optical surfaces of the second surface and the fourteenth surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in Equation [10] are as follows.

Aspherical parameter second surface K = 2.88011
A ₄ = 8.1328 × 10 ⁻⁵
A ₆ = −8.551224 × 10 ⁻⁷
A ₈ = 5.97881 × 10 ⁻⁸
A ₁₀ = −9.776289 × 10 ⁻¹⁰
14th surface K = −0.71102
A ₄ = 2.26643 × 10 ⁻⁴
A ₆ = 2.60218 × 10 ⁻⁶
A ₈ = 6.37436 × 10 ⁻⁸
A ₁₀ = −6.007070 × 10 ⁻¹⁰
In this case, the values corresponding to the conditional expressions [1] to [9] are as follows, and satisfy the conditional expressions [1] to [9], respectively.

[1] (r _1o + r _2o ) / (r _1o −r _2o ) = − 0.225
[2] (r _1i + r _2i ) / (r _1i −r _2i ) = 0.107
[3] (r _1s + r _2s ) / (r _1s −r _2s ) = 0.414
[4] f _F / f _R = 1.107
[5] Y '/ f = 0.76
[6] tan (θP _max ) = 0.551
[7] L / f = 1.763
[8] D _T /f=1.010
[9] f _FF / f _RR = 0.160
FIG. 14 shows aberration curves of various aberrations at the d-line and g-line of the imaging lens according to Example 7, that is, spherical aberration, astigmatism, distortion aberration, and coma aberration. In the aberration curve diagram of FIG. 14, the broken line in spherical aberration represents the sine condition, the solid line in astigmatism represents sagittal, and the broken line represents meridional. Further, d and g in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent d-line and g-line, respectively. The same applies to the aberration curve diagrams according to other examples.

FIG. 15 shows a lens configuration of a longitudinal section along the optical axis of the optical system of the imaging lens according to Example 8 of the present invention.
That is, the optical system of the imaging lens according to Example 8 of the present invention, as shown in FIG. 15, sequentially from the object side to the image plane side, the first lens L1, the second lens L2, and the third lens. L3, stop AD, fourth lens L4, fifth lens L5, sixth lens L6, and seventh lens L7 are arranged, the fourth lens L4 and fifth lens L5, and the sixth lens L6 and seventh lens. L7 constitutes a cemented lens, and has a so-called 5 group 7 element configuration.
Focusing on the lens group configuration, the first lens L1 to the third lens L3 constitute a first lens group G1 as a front lens group having a positive refractive power, and the fourth lens L4 to the seventh lens L7 are positive. A second lens group G2 is configured as a rear lens group having refractive power. That is, the optical system of the imaging lens shown in FIG. 15 has a configuration in which the first lens group G1, the stop AD, and the second lens group G2 are sequentially arranged from the object side to the image plane side.

Specifically, the first lens group G1 serving as the front lens group has a negative meniscus having a convex surface on the object side and a concave surface formed with an aspheric surface on the image side sequentially from the object side to the image side. A first lens L1 made of a negative lens having a shape, a second lens L2 made of a plano-concave shape having a concave surface facing the object side, and a convex surface having a larger curvature than the image side surface directed to the object side And a third lens L3 made of a positive lens having a biconvex shape is arranged so that the first lens group G1 exhibits positive refractive power.
A stop AD is disposed between the first lens group G1 as the front lens group and the second lens group G2 as the rear lens group.
The second lens group G2 as a rear lens group is a fourth lens composed of a positive lens having a biconvex shape with a convex surface having a larger curvature than the object side surface facing the image side sequentially from the object side to the image side. It consists of a lens L4, a fifth lens L5 that is a negative lens having a biconcave shape with a concave surface having a larger curvature than the image side surface facing the object side, and a negative lens having a negative meniscus shape that is concave on the object side. A sixth lens L6 and a seventh lens L7 having a positive meniscus shape that is convex on the image side and formed with an aspheric surface are arranged so as to exhibit positive refractive power as the second lens group G2. It is composed. Note that the two lenses, the fourth lens L4 and the fifth lens L5, are closely bonded to each other and are integrally joined to form a cemented lens composed of two lenses. In addition, the two lenses of the sixth lens L6 and the seventh lens L7 are closely bonded to each other and integrally joined to form a cemented lens composed of two lenses.

An air lens having a biconvex shape is formed between the first lens L1 and the second lens L2 in the first lens group G1, which is the front lens group. In addition, an air lens having a biconvex shape is formed between the fifth lens L5 and the sixth lens L6 in the second lens group G2, which is the rear lens group.
Further, various filters such as an optical low-pass filter and an infrared cut filter and a cover glass (seal glass) of a light receiving element are equivalently provided behind these first lens group G1 and second lens group G2, that is, on the image side. A filter glass FG shown as a parallel plate is disposed.
The first lens group G1, the aperture stop AD, and the second lens group G2 are supported almost integrally by an appropriate support frame or the like at least during use. Perform focusing.
FIG. 15 also shows the surface numbers of the optical surfaces in the optical system of the imaging lens. Note that each reference symbol shown in FIG. 15 is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference symbol. Therefore, FIG. 1, FIG. 3, FIG. 7, FIG. 9, FIG. 11, FIG. 13, FIG. 17, FIG. 19, and the like are not necessarily in common with the corresponding embodiments.
In Example 8, the focal length f, the open F value F, and the half angle of view ω [degrees] of the entire optical system are f = 18.30, F = 2.88, and ω = 38.2, respectively. , Radius of curvature of optical surfaces (paraxial radius of curvature for aspheric surfaces) R, surface distance D of adjacent optical surfaces, refractive index Nd, Abbe number νd, and lens characteristics, etc. Is as shown in Table 8 below.

Also in Table 8, the lens surface with the surface number indicated by adding “*” to the surface number is an aspherical surface. In addition, the name of the manufacturer is abbreviated as HOYA (HOYA Corporation) or the like before the glass type name of the glass material of the optical glass lens. The same applies to the other embodiments.
That is, in Table 8, the optical surfaces of the second surface and the thirteenth surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation [10] are as follows.

Aspherical parameters Second surface K = 2.31354
A ₄ = 4.339060 × 10 ⁻⁵
A ₆ = −1.54647 × 10 ⁻⁶
A ₈ = 9.994796 × 10 ⁻⁸
A ₁₀ = −1.38635 × 10 ⁻⁹
13th surface K = -2.61685
A ₄ = 2.77565 × 10 ⁻⁴
A ₆ = 4.58115 × 10 ⁻⁶
A ₈ = 1.02845 × 10 ⁻⁷
A ₁₀ = −1.35694 × 10 ⁻⁹
In this case, the values corresponding to the conditional expressions [1] to [9] are as follows, and satisfy the conditional expressions [1] to [9], respectively.

[1] (r _1o + r _2o ) / (r _1o −r _2o ) = − _0.215
[2] (r _1i + r _2i ) / (r _1i −r _2i ) = 0.295
[3] (r _1s + r _2s ) / (r _1s −r _2s ) = 0.425
[4] f _F / f _R = 1.938
[5] Y '/ f = 0.76
[6] tan (θP _max ) = 0.727
[7] L / f = 1.657
[8] D _T /f=0.858
[9] _{f FF} / f RR = 0.302
FIG. 16 shows aberration curves of various aberrations at the d-line and g-line of the imaging lens according to Example 8, that is, spherical aberration, astigmatism, distortion aberration, and coma aberration. In the aberration curve diagram of FIG. 18, the broken line in spherical aberration represents the sine condition, the solid line in astigmatism represents sagittal, and the broken line represents meridional. Further, d and g in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent d-line and g-line, respectively. The same applies to the aberration curve diagrams according to other examples.

FIG. 17 shows a lens configuration of a longitudinal section along the optical axis of the optical system of the imaging lens according to the ninth embodiment of the present invention and Example 9.
That is, as shown in FIG. 17, the optical system of the imaging lens according to Example 9 of the present invention sequentially has a first lens L1, a second lens L2, and a third lens from the object side to the image surface side. L3, a fourth lens L4, an aperture stop AD, a fifth lens L5, a sixth lens L6, and a seventh lens L7 are arranged. The third lens L3 and the fourth lens L4, and the fifth lens L5 and the sixth lens. L6 respectively constitutes a cemented lens, and has a so-called five-group seven-element configuration.
Focusing on the lens group configuration, the first lens L1 to the fourth lens L4 constitute a first lens group G1 as a front lens group having a positive refractive power, and the fifth lens L5 to the seventh lens L7 are positive. A second lens group G2 is configured as a rear lens group having refractive power. That is, the optical system of the imaging lens shown in FIG. 5 has a configuration in which the first lens group G1, the stop AD, and the second lens group G2 are sequentially arranged from the object side to the image plane side.
Specifically, the first lens group G1 as the front lens group has an aspheric surface on the image side sequentially from the object side to the image side, and a concave surface having a larger curvature than the object side surface. The first lens L1 is a negative lens having a biconcave shape, the second lens L2 is a negative lens having a plano-concave shape with the concave surface facing the object side, and a negative meniscus shape having a convex shape on the object side. A third lens L3 made of a negative lens and a fourth lens L4 made of a positive lens having a biconvex shape with a convex surface having a larger curvature than the image side surface are disposed on the object side, and the first lens group G1 is arranged. As shown in FIG. Note that the two lenses, the third lens L3 and the fourth lens L4, are closely bonded to each other and integrally joined to form a cemented lens composed of two lenses.

A stop AD is disposed between the first lens group G1 as the front lens group and the second lens group G2 as the rear lens group.
The second lens group G2 as the rear lens group is a fifth lens including a positive lens having a biconvex shape with a convex surface having a larger curvature than the object side surface facing the image side sequentially from the object side to the image side. A lens L5, a sixth lens L6 composed of a negative lens having a biconcave shape with a concave surface having a larger curvature than the image side surface facing the object side, an aspherical surface facing the concave surface on the object side and an image side A seventh lens L7 having a negative meniscus shape that is convex on the image side is disposed, and the second lens group G2 is configured to exhibit positive refractive power. Note that the two lenses of the fifth lens L5 and the sixth lens L6 are closely bonded to each other and are integrally joined to form a cemented lens composed of two lenses.
An air lens having a biconvex shape is formed between the first lens L1 and the second lens L2 in the first lens group G1, which is the front lens group. In addition, an air lens having a biconvex shape is formed between the sixth lens L6 and the seventh lens L7 in the second lens group G2, which is the rear lens group.

Further, various filters such as an optical low-pass filter and an infrared cut filter and a cover glass (seal glass) of a light receiving element are equivalently provided behind these first lens group G1 and second lens group G2, that is, on the image side. A filter glass FG shown as a parallel plate is disposed.
The first lens group G1, the aperture stop AD, and the second lens group G2 are supported almost integrally by an appropriate support frame or the like at least during use. Perform focusing.
FIG. 17 also shows the surface numbers of the optical surfaces in the optical system of the imaging lens. Note that each reference symbol shown in FIG. 17 is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference symbol. Therefore, FIG. 1, FIG. 3, FIG. 7, FIG. 9, FIG. 11, FIG. 13, FIG. 15, FIG. 19, and the like are not necessarily in common with the corresponding embodiments.
In Example 9, the focal length f, the open F value F, and the half angle of view ω [degrees] of the entire optical system are f = 18.29, F = 2.86, and ω = 38.2, respectively. , The curvature radius of the optical surface (paraxial curvature radius for an aspheric surface) R, the surface interval D of adjacent optical surfaces, the refractive index Nd, the Abbe number νd, and the optical characteristics of each optical element in Example 9 Is as shown in Table 9 below.

Also in Table 9, the lens surface with the surface number indicated by adding “*” to the surface number is an aspherical surface. In addition, the name of the manufacturer is abbreviated as HOYA (HOYA Corporation) or the like before the glass type name of the glass material of the optical glass lens. The same applies to the other embodiments.
That is, in Table 9, the optical surfaces of the second surface and the thirteenth surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation [10] are as follows.

Aspherical parameter second surface K = 3.95417
A ₄ = 1.27851 × 10 ⁻⁴
A ₆ = −3.05355 × 10 ⁻⁶
A ₈ = 1.84561 × 10 ⁻⁷
A ₁₀ = −4.22293 × 10 ⁻⁹
13th surface K = -1.85186
A ₄ = 1.70529 × 10 ⁻⁴
A ₆ = 5.26357 × 10 ⁻⁶
A ₈ = 7.998688 × 10 ⁻⁸
A ₁₀ = 4.882347 × 10 ⁻¹⁰
In this case, the values corresponding to the conditional expressions [1] to [9] are as follows, and satisfy the conditional expressions [1] to [9], respectively.

[1] (r _1o + r _2o ) / (r _1o −r _2o ) = − 0.345
[2] (r _1i + r _2i ) / (r _1i −r _2i ) = 0.008
[3] (r _1s + r _2s ) / (r _1s −r _2s ) = 0.347
[4] f _F / f _R = 0.879
[5] Y '/ f = 0.76
[6] tan (θP _max ) = 0.757
[7] L / f = 1.658
[8] D _T /f=0.858
[9] f _FF / f _RR = 0.074
FIG. 18 shows aberration curves of various aberrations in the d-line and g-line of the imaging lens according to Example 9, that is, spherical aberration, astigmatism, distortion aberration, and coma aberration. In the aberration curve diagram of FIG. 18, the broken line in spherical aberration represents the sine condition, the solid line in astigmatism represents sagittal, and the broken line represents meridional. Further, d and g in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent d-line and g-line, respectively. The same applies to the aberration curve diagrams according to other examples.

FIG. 19 shows a lens configuration of a longitudinal section along the optical axis of the optical system of the imaging lens according to the tenth embodiment of the present invention and Example 10.
That is, as shown in FIG. 19, the optical system of the imaging lens according to Example 10 of the present invention sequentially has a first lens L1, a second lens L2, and a third lens from the object side to the image surface side. L3, stop AD, fourth lens L4, fifth lens L5, and sixth lens L6 are disposed. The fourth lens L4 and the fifth lens L5 constitute a cemented lens, so-called five elements in six groups. It is configured.
Focusing on the lens group configuration, the first lens L1 to the third lens L3 constitute a first lens group G1 as a front lens group having a positive refractive power, and the fourth lens L4 to the sixth lens L6 are positive. A second lens group G2 is configured as a rear lens group having refractive power. That is, the optical system of the imaging lens shown in FIG. 19 has a configuration in which the first lens group G1, the stop AD, and the second lens group G2 are sequentially arranged from the object side to the image plane side.

Specifically, the first lens group G1 as the front lens group has an aspheric surface on the image side sequentially from the object side to the image side, and a concave surface having a larger curvature than the object side surface. A first lens L1 made of a negative lens having a biconcave shape, a second lens L2 made of a negative lens having a negative meniscus shape having a concave surface facing the object side and a convex shape on the image side, and an image on the object side A third lens L3 made of a positive lens having a biconvex shape with a convex surface having a larger curvature than the side surface is disposed, and the first lens group G1 is configured to exhibit positive refractive power.
A stop AD is disposed between the first lens group G1 as the front lens group and the second lens group G2 as the rear lens group.
The second lens group G2 as a rear lens group is a fourth lens composed of a positive lens having a biconvex shape with a convex surface having a larger curvature than the object side surface facing the image side sequentially from the object side to the image side. A lens L4, a fifth lens L5 composed of a negative lens having a biconcave shape with a concave surface having a larger curvature than the image side surface facing the object side, a concave surface facing the object side and an aspheric surface facing the image side A negative meniscus sixth lens L6 having a convex shape on the image side is disposed, and the second lens group G2 is configured to exhibit a positive refractive power. Note that the two lenses, the fourth lens L4 and the fifth lens L5, are closely bonded to each other and are integrally joined to form a cemented lens composed of two lenses.

An air lens having a biconvex shape is formed between the first lens L1 and the second lens L2 in the first lens group G1, which is the front lens group. In addition, an air lens having a biconvex shape is formed between the fifth lens L5 and the sixth lens L6 in the second lens group G2, which is the rear lens group.
Further, various filters such as an optical low-pass filter and an infrared cut filter and a cover glass (seal glass) of a light receiving element are equivalently provided behind these first lens group G1 and second lens group G2, that is, on the image side. A filter glass FG shown as a parallel plate is disposed.
The first lens group G1, the aperture stop AD, and the second lens group G2 are supported almost integrally by an appropriate support frame or the like at least during use. Perform focusing.
FIG. 19 also shows the surface numbers of the optical surfaces in the optical system of the imaging lens. Note that each reference symbol shown in FIG. 17 is used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference symbol. Therefore, FIG. 1, FIG. 3, FIG. 7, FIG. 9, FIG. 11, FIG. 13, FIG. 15, FIG. 17, and the like are not necessarily in common with the corresponding embodiments.
In Example 10, the focal length f, the open F value F, and the half angle of view ω [degrees] of the entire optical system are f = 18.34, F = 2.88, and ω = 38.2, respectively. , The optical surface curvature radius (paraxial radius of curvature for an aspheric surface) R, the surface spacing D of adjacent optical surfaces, the refractive index Nd, the Abbe number νd, and the lens material, etc. Is as shown in Table 10 below.

Also in Table 10, the lens surface with the surface number indicated by adding “*” to the surface number is an aspherical surface. In addition, the name of the manufacturer is abbreviated as HOYA (HOYA Corporation) or the like before the glass type name of the glass material of the optical glass lens. The same applies to the other embodiments.
That is, in Table 10, the optical surfaces of the second surface and the twelfth surface with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation [10] are as follows.

Aspherical parameter second surface K = 5.10838
A ₄ = 1.41564 × 10 ⁻⁴
A ₆ = −5.85441 × 10 ⁻⁶
A ₈ = 4.02424 × 10 ⁻⁷
A ₁₀ = −1.02386 × 10 ⁻⁸
Twelfth surface K = −1.04743
A ₄ = 2.38348 × 10 ⁻⁴
A ₆ = 6.15092 × 10 ⁻⁶
A ₈ = 9.61558 × 10 ⁻⁸
A ₁₀ = 2.11010 × 10 ⁻¹⁰
In this case, the values corresponding to the conditional expressions [1] to [9] are as follows, and satisfy the conditional expressions [1] to [9], respectively.

[1] (r _1o + r _2o ) / (r _1o −r _2o ) = − 0.118
[2] (r _1i + r _2i ) / (r _1i −r _2i ) = 0.057
[3] (r _1s + r _2s ) / (r _1s −r _2s ) = 0.236
[4] f _F / f _R = 1.398
[5] Y '/ f = 0.76
[6] tan (θP _max ) = 0.746
[7] L / f = 1.626
[8] D _T /f=0.721
[9] _{f FF} / f RR = 0.148
[Eleventh embodiment]
Next, an eleventh embodiment of the present invention, in which an imaging lens such as the first to tenth embodiments of the first to tenth embodiments of the present invention described above is employed as an imaging optical system, is described. An imaging apparatus according to the embodiment will be described with reference to FIGS.
FIG. 21 schematically shows an external configuration of a digital camera as an imaging apparatus according to the eleventh embodiment of the present invention viewed from the subject side (that is, the front side that is the object side). The perspective view which shows the state which the imaging lens which consists of the imaging lens comprised according to the 1st Embodiment of this invention is collapsed in the body of a digital camera, and (b) is an imaging lens from the body of a digital camera It is a perspective view which shows the state which has protruded. FIG. 22 is a perspective view schematically showing an external configuration of the digital camera viewed from the photographer side (that is, the back side). FIG. 23 is a block diagram schematically showing the functional configuration of the digital camera.
Although a digital camera as an imaging device is described here, it is called not only an imaging device mainly for imaging including a video camera and a film camera, but also a mobile phone, a personal data assistant (PDA), and the like. In many cases, an imaging function corresponding to a digital camera or the like is incorporated in various information devices including a portable information terminal device and a portable terminal device called a smartphone that combines these functions. Although such an information device also has a slightly different appearance, it includes substantially the same functions and configurations as a digital camera or the like, and the imaging lens according to the present invention may be employed in such an information device. .

As shown in FIGS. 21 and 22, the digital camera includes an imaging lens 101, a shutter button 102, a zoom button 103, a finder 104, a strobe 105, a liquid crystal monitor 106, an operation button 107, a power switch 108, a memory card slot 109, and communication. A card slot 110 and the like are provided. Furthermore, as shown in FIG. 23, the digital camera also includes a light receiving element 111, a signal processing device 112, an image processing device 113, a central processing unit (CPU) 114, a semiconductor memory 115, a communication card, and the like 116.
The digital camera includes an imaging lens 101 and a light receiving element 111 as an area sensor such as a CMOS (complementary metal oxide semiconductor) imaging device or a CCD (charge coupled device) imaging device, and is an imaging optical system. An optical image of an object to be imaged, that is, a subject is formed by the lens 101, and this optical image is read by the light receiving element 111. As the imaging lens 101, that have used an imaging lens according to the first to tenth embodiment of the present invention as described in Examples 1 to 10.

The output of the light receiving element 111 is processed by the signal processing device 112 controlled by the central processing unit 114 and converted into digital image information. The image information digitized by the signal processing device 112 is recorded in a semiconductor memory 115 such as a non-volatile memory after being subjected to predetermined image processing in an image processing device 113 also controlled by the central processing unit 114. In this case, the semiconductor memory 115 may be a memory card loaded in the memory card slot 109 or a semiconductor memory built in the digital camera body. The liquid crystal monitor 106 can display an image being shot, or can display an image recorded in the semiconductor memory 115.
The image recorded in the semiconductor memory 115 can also be transmitted to the outside via a communication card 116 or the like loaded in the communication card slot 110.
When the digital camera is carried, the imaging lens 101 is retracted and buried in the body of the digital camera as shown in FIG. 21A. When the user operates the power switch 108 to turn on the power, As shown in FIG. 21B, the lens barrel is extended and protrudes from the body of the digital camera. By operating the zoom button 103, it is possible to perform so-called digital zoom type zooming in which the cut-out range of the subject image is changed and pseudo zooming is performed. At this time, it is desirable that the optical system of the finder 104 is also scaled in conjunction with the change in the effective field angle.
In many cases, focusing is performed by half-pressing the shutter button 102.

When the shutter button 102 is further pushed down to the fully depressed state, photographing is performed, and then the processing as described above is performed.
When the image recorded in the semiconductor memory 115 is displayed on the liquid crystal monitor 106 or transmitted to the outside via the communication card 116 or the like, the operation button 107 is operated in a predetermined manner. The semiconductor memory 115 and the communication card 116 are used by being loaded into dedicated or general-purpose slots such as the memory card slot 109 and the communication card slot 110, respectively.
When the imaging lens 101 is in the retracted state, the groups of the imaging lenses do not necessarily have to be aligned on the optical axis. For example, if the mechanism is such that the second lens group G2 is retracted from the optical axis and retracted in parallel with the first lens group G1 when retracted, the digital camera can be made thinner.
As described above, the digital camera (imaging device) or information device as described above is configured using the imaging lens shown in Examples 1 to 10 according to the first to tenth embodiments. The photographic lens 101 can be used as an imaging optical system. Accordingly, it is possible to realize a small digital camera (imaging device) or information device with high image quality using light receiving elements having 12 to 24 million pixels or more.

G1 first lens group (front lens group)
G2 Second lens group (rear lens group)
L1 1st lens L2 2nd lens L3 3rd lens L4 4th lens L5 5th lens L6 6th lens L7 7th lens L8 8th lens AD Aperture FG Filter glass 101 Imaging lens (imaging lens)
102 shutter button 103 zoom button 104 finder 105 strobe 106 liquid crystal monitor 107 operation button 108 power switch 109 memory card slot 110 communication card slot 111 light receiving element (area sensor)
112 signal processing device 113 image processing device 114 central processing unit (CPU)
115 Semiconductor memory 116 Communication card, etc.

JP-A-8-313802 JP-A-11-326756 JP 2005-352060 A JP 2012-8347 A

Claims (13)

An imaging lens composed of a plurality of lenses,
An air space between two adjacent lenses that are spaced apart from each other and that is sandwiched between the object side surface of the object side lens and the object side surface of the image side lens is referred to as an air lens. And the object side surface of the air lens, the object side surface of the image side lens is the image side surface of the air lens, and the shape of the air lens is defined,
Among the imaging lenses, the air lens having a negative power is only two lenses , an air lens located closest to the object side and an air lens located closest to the image side, and both are biconvex ,
Let L be the distance from the most object-side surface of the imaging lens to the image plane when focused on an object at infinity, and f be the focal length of the entire imaging lens system when focused on an object at infinity. ,
Conditional expression:
[7] 1.4 <L / f <2.0
An imaging lens that satisfies the following . The imaging lens, in order from the object side to the image side, a front lens group having a positive refractive power, a stop, and a rear lens group having a positive refractive power are disposed.
The air lens located closest to the object side is disposed in the front lens group, and the air lens located closest to the image side is disposed in the rear lens group. 2. The imaging lens according to 1 . An imaging lens composed of a plurality of lenses,
An air space between two adjacent lenses that are spaced apart from each other and that is sandwiched between the object side surface of the object side lens and the object side surface of the image side lens is referred to as an air lens, and the image side surface of the object side lens. And the object side surface of the air lens, the object side surface of the image side lens is the image side surface of the air lens, and the shape of the air lens is defined,
Among the imaging lenses, the air lens located closest to the object side and the air lens located closest to the image side are both biconvex,
The imaging lens, in order from the object side to the image side, a front lens group having a positive refractive power, a stop, and a rear lens group having a positive refractive power are disposed.
The air lens located closest to the object side is disposed in the front lens group, and the air lens located closest to the image side is disposed in the rear lens group;
Assuming that the maximum image height is Y ′, the focal length of the entire imaging lens system in the state of focusing on an object at infinity is f, and the incident angle of the principal ray reaching the maximum image height to the image plane is θP _max .
Conditional expression:
[5] 0.7 <Y ′ / f <0.95
[6] 0.6 <tan (θP _max ) <0.95
An imaging lens characterized by satisfying Let L be the distance from the most object-side surface of the imaging lens to the image plane when focused on an object at infinity, and f be the focal length of the entire imaging lens system when focused on an object at infinity. ,
Conditional expression:
[7] 1.4 <L / f <2.0
The imaging lens according to claim 3 , wherein: Air lens having a negative power in the imaging lens according to claim 3, wherein the only two air lens of the air lens positioned on the air lens closest to the image side which is positioned closest to the object side or The imaging lens according to claim 4 . The imaging lens according to claim 2 , wherein each of the front lens group and the rear lens group includes three or more lenses and four or less lenses. The imaging lens according to claim 6 , wherein a most image side surface of the front lens group and a most object side surface of the rear lens group are both convex surfaces. Let r ₁ s be the radius of curvature of the surface closest to the image side of the front lens group, and r ₂ s be the radius of curvature of the surface closest to the object side of the rear lens group.
Conditional expression:
[3] −0.2 <(r ₁ s + r ₂ s) / (r ₁ s−r ₂ s) <0.7
The imaging lens according to claim 7 , wherein: The focal length of the front lens group is f _F and the focal length of the rear lens group is f _R.
Conditional expression:
[4] 0.3 <f _F / f _R <2.5
The imaging lens according to any one of claims 4 to 8 , wherein the imaging lens is satisfied. Before SL most a radius of curvature of the object side surface of the air lens positioned on the object side r _{1 o,} of the most object r ₂ the radius of curvature of the image side surface of the air lens positioned on the side _o, air lens positioned closest to the image side Let r ₁ i be the radius of curvature of the object side surface, and r ₂ i be the radius of curvature of the image side surface of the air lens located closest to the image side.
Conditional expression:
[1] −0.6 <(r ₁ o + r ₂ o) / (r ₁ o−r ₂ o) <0.3
[2] −0.2 <(r ₁ i + r ₂ i) / (r ₁ i−r ₂ i) <0.5
The imaging lens according to claim 1, wherein: DT is the distance from the most object-side surface of the imaging lens to the most image-side surface of the imaging lens, and f is the focal length of the entire imaging lens system when focused on an infinite object.
Conditional expression:
[8] 0.7 <DT / f <1.2
An imaging lens according to any one of claims 1 to 10, characterized by satisfying the. An imaging apparatus comprising: the imaging optical system configured by the imaging lens according to any one of claims 1 to 11 . An information apparatus having an imaging function, wherein the imaging optical system is configured by the imaging lens according to any one of claims 1 to 11 .

Images