JP2019191523A - Image capturing lens and image capturing device - Google Patents

Abstract

To provide an image capturing lens which has a wide view angle and high resolving power and can be reduced in size in a lens radial direction.SOLUTION: An image capturing lens is provided, comprising an aperture stop, a first lens L1 having positive refractive power, a second lens L2 having negative refractive power, and a third lens L3 having positive refractive power arranged in order from the object side. The image capturing lens also has a last lens L5 disposed on the most image side, the last lens having an aspherical image-side surface with an extremum located at a position other than an intersection between the aspherical surface and an optical axis. The image capturing lens satisfies predetermined conditions to achieve a wide angle of view and high resolving power while minimizing an increase in size in a lens radial direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging lens and an imaging device, and more particularly, to an imaging lens suitable for a small imaging device equipped with an imaging device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), and the imaging lens. The present invention relates to an imaging apparatus.

  In recent years, as the number of pixels of an image sensor such as a CCD or a COMS has been increased, the image pickup lens is also required to have a high resolving power compatible with such an image sensor. The same applies to an imaging lens mounted on a small imaging device that has been widely spread in recent years and can be easily carried or installed even in a small space.

  In addition, even in a small-sized imaging device, since a photographing range can be widened compared with an imaging lens with a standard angle of view, an imaging lens with a wide angle of view is demanded from the market. In particular, in the case of wide-angle imaging lenses, they may be used for applications that shoot a wide range and expand locally, so high resolution is strongly demanded, and various imaging lenses are proposed to meet such demands. (For example, refer to Patent Documents 1 and 2.)

JP 2014-163970 A JP2015-121668A

  By the way, small cameras such as those of smartphones and mobile phones often have a fixed aperture with a fixed aperture diameter, but even small cameras have large aperture diameters. There is also a desire to install a variable aperture that can be changed. This is because when the variable aperture is mounted, not only can the brightness be adjusted with the aperture, but also the depth of field and blur can be controlled. However, when mounting a unit that has movable parts near the diaphragm, such as a variable diaphragm, unlike the fixed diaphragm, the mechanical mechanism is likely to be complicated and a large space is required. When considering the size including mechanical parts, there is a problem that it is easy to enlarge in the radial direction of the lens. In addition, in order to prevent the enlargement of the lens in the radial direction, a space equivalent to the aperture unit is required to dispose the aperture, such as a variable aperture, or an aperture unit having movable parts near the aperture on the most object side. Therefore, it is necessary to secure the distance from the stop to the lens not at 0 mm but at least about 0.1 mm.

  For example, Patent Document 1 discloses a small imaging lens having an angle of view of about 80 °, an F-number of about 2.3, and a total length shorter than a sensor diagonal. However, in this imaging lens, it is difficult to install a variable diaphragm because the diaphragm is disposed on the optical axis so as to contact the lens surface on the image side rather than the object side surface of the most object side lens. .

  In general, when the aperture position is changed in the imaging lens, the way the off-axis rays pass to the lens changes, and off-axis aberrations may fluctuate greatly. In the imaging lens disclosed in Japanese Patent Application Laid-Open No. H10-228688, when a variable stop is to be disposed on the most object side, the stop must be disposed on the object side with respect to the most object side lens and with a certain space between the lens. However, since the imaging lens disclosed in Patent Document 1 has a strong convex shape on the object side surface of the most object side lens, the incidence angle of off-axis rays to the lens surface increases and the generation of astigmatism increases. However, it was difficult to maintain high resolution.

  Patent Document 2 discloses a small imaging lens having an angle of view of about 76 °, an F-number of about 2.5, and a total length shorter than the diagonal length of the sensor. In this imaging lens, since the diaphragm is arranged between the first lens and the second lens, when a diaphragm unit having a diaphragm such as a variable diaphragm or a movable part in the vicinity of the diaphragm is employed, even mechanical parts are included. There was a tendency for the size to increase especially in the radial direction of the lens.

  The present invention eliminates the problems caused by the prior art described above, even when a diaphragm unit having a movable part near the diaphragm, such as a variable diaphragm that can change the size of the diaphragm diameter, is mounted in the lens system. An object of the present invention is to provide an imaging lens having a wide angle of view and a high resolving power that can be reduced in the radial direction of the lens in a lens unit including mechanical parts and the like. It is another object of the present invention to provide an image pickup apparatus including a small image pickup lens having a wide field angle and high resolution.

In order to solve the above-described problems and achieve the object, an imaging lens according to the present invention has an aperture stop, a first lens having a positive refractive power, and a negative refractive power, which are arranged in order from the object side. A second lens and a third lens having a positive refractive power, the image side surface being an aspherical surface closest to the image side, and a position other than the intersection of the aspherical surface and the optical axis A final lens having a shape having an extreme value is disposed, and the following conditional expression is satisfied.
(1) -2.81 ≦ f / r1f ≦ 1.65
(2) 0.042 ≦ L / Ymax ≦ 0.830
Where f is the focal length of the entire imaging lens system, r1f is the paraxial radius of curvature of the object side surface of the first lens, L is the distance on the optical axis from the aperture stop to the object side surface of the first lens, and Ymax. Indicates the maximum image height of the imaging lens.

  According to the present invention, even in the case where a diaphragm unit having a movable part near the diaphragm, such as a variable diaphragm that can change the size of the diaphragm diameter, is mounted in the lens system, the lens unit including mechanical parts and the like It is possible to provide an imaging lens having a wide angle of view and high resolving power that can be reduced in size in the radial direction of the lens.

  An imaging apparatus according to the present invention includes the imaging lens and an imaging element that converts an optical image formed by the imaging lens into an electrical signal.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device provided with the imaging lens which has a small size and a wide angle of view, and high resolution can be provided.

  According to the present invention, even when a diaphragm unit having a movable part near the diaphragm, such as a variable diaphragm that can change the size of the diaphragm diameter, is mounted, the lens unit in the lens unit including the mechanical parts, etc. There is an effect that it is possible to provide an imaging lens having a wide angle of view and high resolving power that can be reduced in size in the radial direction. In addition, there is an effect that it is possible to provide an imaging apparatus including an imaging lens having a small size, a wide angle, and a high resolution.

1 is a cross-sectional view along the optical axis showing the configuration of an imaging lens according to Example 1. FIG. FIG. 3 is a longitudinal aberration diagram of the imaging lens according to Example 1; FIG. 6 is a cross-sectional view along the optical axis showing the configuration of an imaging lens according to Example 2. 6 is a longitudinal aberration diagram of the imaging lens according to Example 2. FIG. FIG. 6 is a cross-sectional view along the optical axis showing the configuration of the imaging lens according to Example 3; 6 is a longitudinal aberration diagram of the imaging lens according to Example 3. FIG. FIG. 6 is a cross-sectional view along the optical axis showing the configuration of an imaging lens according to Example 4; FIG. 6 is a longitudinal aberration diagram of the imaging lens according to Example 4; FIG. 6 is a cross-sectional view along the optical axis showing the configuration of an imaging lens according to Example 5. FIG. 10 is a longitudinal aberration diagram of the imaging lens according to Example 5; FIG. 6 is a cross-sectional view along the optical axis showing the configuration of an imaging lens according to Example 6; FIG. 10 is a longitudinal aberration diagram of the imaging lens according to Example 6; FIG. 10 is a cross-sectional view along the optical axis showing the configuration of an imaging lens according to Example 7. FIG. 10 is a longitudinal aberration diagram of the imaging lens according to Example 7. FIG. 10 is a cross-sectional view along the optical axis showing the configuration of an imaging lens according to Example 8. FIG. 10 is a longitudinal aberration diagram of the imaging lens according to Example 8. It is a figure which shows one application example of the imaging device provided with the imaging lens concerning this invention.

  Hereinafter, preferred embodiments of an imaging lens and an imaging apparatus according to the present invention will be described in detail.

  In the imaging lens according to the present invention, an aperture stop, a first lens having a positive refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power are sequentially arranged from the object side. Further, the final lens is arranged on the most image side.

  In the imaging lens according to the present invention, even if an aperture stop having a movable part near the stop, such as a variable stop, is mounted by arranging the aperture stop closest to the object side, for example, mechanical parts It is possible to reduce the size of the lens unit including the above. More specifically, by disposing the diaphragm on the most object side, the diaphragm unit components can be disposed on the object side instead of the lens side, so that the flange portion outside the lens effective diameter and the diaphragm unit do not interfere with each other. An aperture unit that tends to increase in size in the direction can be arranged close to the optical axis side. As a result, in the lens unit including the mechanical parts and the like, the reduction in size in the radial direction of the lens is promoted.

  In addition, in the case of a small and wide-field imaging lens, the chief ray angle (hereinafter referred to as CRA) to the image sensor tends to be particularly large. When the CRA is large, there is a problem that the light collection efficiency of the image pickup device is lowered, which causes a deterioration in image quality and a shortage of peripheral light amount. Therefore, if the aperture stop is arranged on the most object side of the lens system, the distance from the image plane to the stop can be increased, so that CRA can be easily suppressed.

  In the present invention, that the aperture stop is disposed closest to the object side means that an optical element having a refractive power such as a lens does not exist on the object side of the aperture stop, and has a refractive power such as a cover glass. The optical element that is not to be considered is considered to be excluded even if it is arranged on the object side from the aperture stop.

  Further, by making the second lens a lens having a negative refractive power, it is possible to satisfactorily correct the longitudinal chromatic aberration and the lateral chromatic aberration, so that high resolution can be achieved. By making the third lens a lens having a positive refractive power, the positive refractive power of the first lens does not have to be increased too much, so that the positive refractive power on the image side surface of the first lens is suppressed and spherical aberration is suppressed. Thus, coma aberration can be corrected well, and high resolution can be achieved.

  Furthermore, the image side surface of the final lens disposed closest to the image side is made an aspherical shape having extreme values at positions other than the vicinity of the intersection between the image side surface of the final lens and the optical axis, thereby increasing the resolution. It becomes possible. In other words, when the shape near the intersection of the image side surface and the optical axis is a concave surface on the image side, the shape of the peripheral portion of the optical effective diameter becomes a convex surface on the image side. On the other hand, when the shape near the intersection of the image side surface and the optical axis is a convex surface on the image side, the shape of the peripheral portion of the optical effective diameter becomes a concave surface on the image side.

  It is more preferable that the aspherical shape of the image side surface of the final lens has a concave surface facing the image side in the vicinity of the optical axis and a convex surface facing the image side in the periphery of the optical effective diameter. As a result, while suppressing the occurrence of spherical aberration and correcting astigmatism at low image height, it is possible to suppress CRA near the maximum image height and prevent image quality deterioration and lack of peripheral light quantity. become.

Furthermore, in the imaging lens according to the present invention, it is preferable that the following conditional expression is satisfied, where f is the focal length of the entire imaging lens system and r1f is the paraxial radius of curvature of the object side surface of the first lens.
(1) -2.81 ≦ f / r1f ≦ 1.65

  Conditional expression (1) defines the preferable range of the focal length of the entire imaging lens system with respect to the paraxial radius of curvature of the object side surface of the first lens, and corrects aberrations well even at a wide angle of view. It is a formula which prescribes | regulates the conditions regarding the shape of the 1st lens for implement | achieving high resolution.

  In the present invention, it is not preferable that the shape of the first lens has a strong positive refractive power on the image side surface, that is, a strong convex shape, because spherical aberration and coma aberration are greatly generated. In addition, since the aperture stop is disposed on the object side of the first lens, if the object side surface of the first lens has a strong positive refractive power, that is, has a strong convex shape, the off-axis light beam on the lens surface As the incident angle increases and astigmatism increases, it is difficult to achieve high resolution. In particular, this tendency is remarkable in an imaging lens having a wide angle of view. Therefore, in the present invention, conditional expression (1) is defined as a condition for solving such a problem.

  If the lower limit of conditional expression (1) is not reached, the negative refracting power of the object side surface of the first lens becomes too strong, and the positive refracting power of the first lens is supplemented by the image side surface. It is difficult to correct spherical aberration and coma well. On the other hand, if the upper limit in conditional expression (1) is exceeded, the positive refractive power of the object side surface of the first lens becomes too strong, making it difficult to correct astigmatism and lateral chromatic aberration well, and wide angle of view. It is difficult to achieve high resolution with this imaging lens.

  The lower limit value of the conditional expression (1) is preferably −2.39 or more, more preferably −1.98 or more, more preferably −1.77 or more, more preferably −1.56 or more, more preferably. May be set to be −1.35 or more. On the other hand, the upper limit value of the conditional expression (1) is preferably set to 1.50 or less, more preferably 1.31 or less, and more preferably 1.26 or less.

Furthermore, in the imaging lens according to the present invention, when the distance on the optical axis from the aperture stop to the object side surface of the first lens is L and the maximum image height of the imaging lens is Ymax, the following conditional expression may be satisfied. preferable.
(2) 0.042 ≦ L / Ymax ≦ 0.830

  Conditional expression (2) is an expression that defines a preferable range of the distance on the optical axis from the aperture stop to the object side surface of the first lens with respect to the maximum image height of the imaging lens.

  In order to avoid the enlargement of the lens system in the radial direction and to dispose a diaphragm unit having a movable part near the diaphragm, such as a variable diaphragm, closer to the object side than the first lens, Since a space for disposing the aperture unit between the first lens and the first lens is required, the distance from the aperture stop to the first lens needs to be at least about 0.1 mm, not 0 mm. However, when the distance from the aperture stop to the first lens is increased, the total length of the lens system is increased, and downsizing of the lens system is hindered. Therefore, in the present invention, the conditional expression (2) is defined as the optimum distance condition from the aperture stop to the first lens.

  If the lower limit of conditional expression (2) is not reached, the distance from the aperture stop to the first lens becomes too short, and the aperture unit having a stop such as a variable stop or a movable part near the stop is more object than the first lens. It becomes difficult to arrange on the side. On the other hand, if the upper limit in conditional expression (2) is exceeded, the distance from the aperture stop to the first lens becomes too long, the overall length of the lens system becomes long, and it becomes difficult to realize a small imaging lens.

  The lower limit value of the conditional expression (2) is preferably set to 0.043 or more, more preferably 0.044 or more, more preferably 0.045 or more, and more preferably 0.046 or more. . On the other hand, the upper limit value of the conditional expression (2) is preferably set to 0.64 or less, more preferably 0.43 or less, more preferably 0.32 or less, and more preferably 0.22 or less. .

  Furthermore, in the imaging lens according to the present invention, it is preferable that the second lens is configured in a shape with a concave surface facing the image side. By configuring the second lens having a negative refractive power so as to have a concave surface facing the image side, the lateral chromatic aberration can be favorably corrected.

Furthermore, in the imaging lens according to the present invention, it is preferable that the following conditional expression is satisfied, where f2 is the focal length of the second lens and f is the focal length of the entire imaging lens system.
(3) −10.0 ≦ f2 / f ≦ −0.55

  Conditional expression (3) is an expression that defines a preferable range of the focal length of the second lens with respect to the focal length of the entire imaging lens system. By satisfying conditional expression (3), the resolving power of the imaging lens can be further improved.

  If the lower limit of conditional expression (3) is not reached, the negative refractive power of the second lens becomes too weak, and the correction effect of lateral chromatic aberration and axial chromatic aberration is likely to be insufficient, and the lateral chromatic aberration and axial chromatic aberration are corrected well. It becomes difficult to do. On the other hand, if the upper limit of conditional expression (3) is exceeded, the negative refractive power of the second lens becomes too strong, and the correction of lateral chromatic aberration and axial chromatic aberration tends to be excessive, and the lateral chromatic aberration and axial chromatic aberration are improved satisfactorily. It becomes difficult to correct.

  The lower limit of the conditional expression (3) is preferably −8.0 or higher, more preferably −6.0 or higher, more preferably −4.8 or higher, more preferably −3.5 or higher, more preferably. Should be set to -2.8 or more. On the other hand, the upper limit value of the conditional expression (3) is preferably −0.58 or less, more preferably −0.61 or less, more preferably −0.63 or less, more preferably −0.66 or less, and more preferably. Is preferably set to −0.69 or less.

Furthermore, in the imaging lens according to the present invention, it is preferable that the following conditional expression is satisfied, where f3 is the focal length of the third lens and f is the focal length of the entire imaging lens system.
(4) 0.45 ≦ f3 / f ≦ 2.00

  Conditional expression (4) is an expression that defines a preferable range of the focal length of the third lens with respect to the focal length of the entire imaging lens system. By satisfying conditional expression (4), the resolving power of the imaging lens can be further improved.

  If the lower limit of conditional expression (4) is not reached, the positive refractive power of the third lens becomes too strong, making it difficult to correct spherical aberration, coma aberration, and astigmatism well. On the other hand, if the upper limit in conditional expression (4) is exceeded, the positive refractive power of the third lens becomes too weak and the positive refractive power of the first lens tends to increase, so that spherical aberration, coma aberration, astigmatism Is difficult to correct well.

  In addition, the lower limit value of the conditional expression (4) is preferably 0.48 or more, more preferably 0.50 or more, more preferably 0.54 or more, more preferably 0.58 or more, and more preferably 0.61. It is good to set it as above. On the other hand, the upper limit value of the conditional expression (4) is preferably 1.84 or less, more preferably 1.79 or less, more preferably 1.67 or less, more preferably 1.55 or less, and more preferably 1.43. It is good to set it as follows.

Furthermore, in the imaging lens according to the present invention, it is preferable that the following conditional expression is satisfied when the refractive index for the d-line of the first lens is nd_1.
(5) nd_1 ≧ 1.58

  Conditional expression (5) is an expression that defines a preferable range of the refractive index for the d-line of the first lens. By satisfying conditional expression (5), the resolving power of the imaging lens can be further improved. If the lower limit of conditional expression (5) is not reached, the curvature of the image side surface of the first lens tends to be tight and it becomes difficult to satisfactorily correct spherical aberration and coma.

  Note that the lower limit value of the conditional expression (5) is preferably set to 1.61 or more, more preferably 1.65 or more, and more preferably 1.69 or more.

  Furthermore, in the imaging lens according to the present invention, it is preferable to dispose a fourth lens having a negative refractive power between the third lens and the final lens. By arranging the fourth lens having negative refractive power between the third lens and the final lens, astigmatism, coma, lateral chromatic aberration, and axial chromatic aberration can be favorably corrected. High resolution can be realized. Further, by configuring the imaging lens with five lenses, it is easy to achieve both high resolution and miniaturization. Increasing the number of lenses increases the ability to correct aberrations, but tends to increase the overall length of the lens system. Therefore, by configuring the imaging lens with five lenses, it is possible to avoid an increase in the total length of the lens system while increasing the aberration correction capability and enabling high resolution.

Furthermore, in the imaging lens according to the present invention, it is preferable that the following conditional expression is satisfied when the focal length of the fourth lens is f4 and the focal length of the final lens is f5.
(6) -1.30 ≦ f4 / f5 ≦ −0.15

  Conditional expression (6) is an expression that defines a preferable range of the focal length of the fourth lens with respect to the focal length of the final lens. By satisfying conditional expression (6), the resolving power of the imaging lens can be further improved. If the lower limit of conditional expression (6) is not reached, the positive refractive power of the final lens will be too strong compared to the fourth lens, and it will be difficult to satisfactorily correct lateral chromatic aberration and astigmatism. On the other hand, if the upper limit in conditional expression (6) is exceeded, the negative refractive power of the fourth lens becomes too strong compared to the final lens, making it difficult to correct astigmatism well.

  The lower limit of the conditional expression (6) is preferably −1.20 or more, more preferably −1.10 or more, more preferably −1.00 or more, more preferably −0.90 or more. It is good to set to. On the other hand, the upper limit value of the conditional expression (6) is preferably −0.18 or less, more preferably −0.21 or less, more preferably −0.24 or less, more preferably −0.27 or less, and more preferably. Is preferably set to −0.30 or less.

Further, in the imaging lens according to the present invention, the distance on the optical axis from the object side surface of the first lens (lens arranged closest to the object side) to the image plane (the back focus portion is an air conversion length) is TTL, When the maximum image height of the imaging lens is Ymax, it is preferable that the following conditional expression is satisfied.
(7) TTL / (2 × Ymax) ≦ 1.5

  Conditional expression (7) is the total length of the lens system (corresponding to the diagonal length of the sensor) twice the maximum image height (on the optical axis from the object side surface of the lens disposed closest to the object side to the image plane). This is a formula that defines a preferable range of (distance) and shows conditions for realizing a reduction in size of the lens system. If the upper limit of conditional expression (7) is exceeded, the total length of the lens system becomes long, which is not preferable.

  The upper limit value of the conditional expression (7) is preferably set to 1.4 or less, more preferably 1.3 or less, more preferably 1.2 or less, and more preferably 1.1 or less. .

Furthermore, in the imaging lens according to the present invention, it is preferable that the following conditional expression is satisfied, where f1 is the focal length of the first lens and f is the focal length of the entire imaging lens system.
(8) 0.49 ≦ f1 / f ≦ 10.0

  Conditional expression (8) is an expression that defines a preferable range of the focal length of the first lens with respect to the focal length of the entire imaging lens system. By satisfying conditional expression (8), it is possible to easily realize both the downsizing and the high resolution of the imaging lens.

  If the lower limit of conditional expression (8) is not reached, the positive refractive power of the first lens becomes too strong, making it difficult to satisfactorily correct spherical aberration, coma and astigmatism. On the other hand, if the upper limit in conditional expression (8) is exceeded, the positive refractive power of the first lens becomes too weak, the lens system overall length tends to be long, and downsizing of the imaging lens is hindered.

  Note that the lower limit value of the conditional expression (8) is preferably set to 0.54 or more, more preferably 0.59 or more, and more preferably 0.64 or more. On the other hand, the upper limit value of the conditional expression (8) is preferably 7.0 or less, more preferably 6.5 or less, more preferably 5.0 or less, more preferably 4.0 or less, more preferably 3.0. It is good to set it as follows.

  In the imaging lens according to the present invention, it is preferable that the first lens has a shape with a convex surface facing the image side. When the first lens is shaped to have a concave surface facing the image side, the object side surface tends to have a strong positive refractive power to supplement the positive refractive power of the first lens on the object side surface, and astigmatism is reduced. Since the generation amount increases, it is not preferable.

Furthermore, in the imaging lens according to the present invention, it is preferable that the following conditional expression is satisfied when the Abbe number of the third lens with respect to the d line is νd_3.
(9) νd — 3 ≧ 40.0

  Conditional expression (9) is an expression that defines an appropriate value of the Abbe number for the d-line of the third lens. If the third lens is formed of a glass material that satisfies the conditional expression (9), the lateral chromatic aberration can be satisfactorily corrected. If the lower limit of conditional expression (9) is not reached, the lateral chromatic aberration cannot be corrected satisfactorily, and it becomes difficult to achieve high resolution.

  Note that the lower limit value of the conditional expression (9) is preferably set to 45.0 or more, more preferably 50.0 or more.

  In the imaging apparatus according to the present invention, it is preferable that the third lens has a shape with a convex surface facing the image side. When the third lens is shaped to have a concave surface facing the image side, the object side surface tends to have a strong positive refractive power to supplement the positive refracting power of the lens with the object side surface. The amount of generation increases, and it becomes difficult to satisfactorily correct lateral chromatic aberration.

Furthermore, in the imaging lens according to the present invention, it is preferable that the following conditional expression is satisfied, where f4 is the focal length of the fourth lens and f is the focal length of the entire imaging lens system.
(10) -1.92 ≦ f4 / f ≦ −0.40

  Conditional expression (10) is an expression that defines a preferable range of the focal length of the fourth lens with respect to the focal length of the entire imaging lens system. By satisfying conditional expression (10), various aberrations can be corrected satisfactorily. If the lower limit of conditional expression (10) is not reached, the negative refractive power of the fourth lens becomes too weak, making it difficult to satisfactorily correct astigmatism, coma, lateral chromatic aberration, and axial chromatic aberration. On the other hand, if the upper limit in conditional expression (10) is exceeded, the negative refractive power of the fourth lens becomes too strong, making it difficult to correct coma and astigmatism satisfactorily.

  In addition, the lower limit value of the conditional expression (10) is preferably −1.81 or more, more preferably −1.70 or more, more preferably −1.60 or more, more preferably −1.47 or more. It is good to set to. On the other hand, the upper limit value of the conditional expression (10) is preferably −0.45 or less, more preferably −0.50 or less, more preferably −0.55 or less, and more preferably −0.60 or less. It is good to set to.

  Further, in the imaging lens of the present invention, if the object side surface of the fourth lens has a concave surface facing the object side, axial chromatic aberration, coma aberration, astigmatism, and lateral chromatic aberration can be corrected well. Furthermore, if the image side surface of the fourth lens has a convex surface facing the image side, the refractive power of the fourth lens does not become too strong, and the refractive powers of the third lens and the fifth lens do not become too strong. Astigmatism can be corrected satisfactorily. Therefore, it is preferable that the fourth lens has a meniscus shape with a concave surface facing the object side.

  As described above, the imaging lens according to the present invention has the above-described configuration, and by satisfying the conditional expression, a movable diaphragm such as a variable diaphragm that can change the size of the diaphragm diameter is movable. Even when the aperture unit is mounted in the lens system, it is possible to reduce the size of the lens in the radial direction of the lens unit including mechanical parts and the like, and to provide a high resolution with a wide angle of view. .

  Furthermore, according to the present invention, the image pickup lens having the above-described configuration and an image pickup element that converts an optical image formed by the image pickup lens into an electrical signal have a small size, a wide angle of view, and high resolution. An imaging device including an imaging lens can be realized.

  Hereinafter, embodiments of an imaging lens according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following examples.

  FIG. 1 is a cross-sectional view along the optical axis showing the configuration of the imaging lens according to the first example. The imaging lens includes, in order from the object side (not shown), an aperture stop STOP, a first lens L1 having a positive refractive power with a convex surface facing the image side, and a first lens having a negative refractive power with a concave surface facing the image side. Two lenses L2, a third lens L3 having a positive refractive power with a convex surface facing the image side, a fourth lens L4 having a meniscus negative refractive power with a concave surface facing the object side, and a positive refractive power And a final lens L5 having an arrangement.

  The aperture stop STOP is for limiting the light beam (light quantity) incident on the optical system. The image side surface of the final lens L5 has an aspheric shape, has an extreme value at a position other than the intersection of the aspheric surface and the optical axis, and has a concave surface facing the image side in the vicinity of the optical axis. In the periphery of the diameter, the convex surface is directed to the image side. A cover glass CG or the like is disposed between the final lens L5 and the image plane IMG as necessary. All the lenses L1 to L5 are both aspherical on both sides.

Various numerical data (optical specification table) relating to the imaging lens according to Example 1 will be shown below. In various numerical data, the surface number indicates the order of surfaces from the object side to the image surface side. r is the radius of curvature (mm) of the lens, aperture stop surface, etc., d is the lens thickness or air spacing (mm), nd is the refractive index for the d-line (λ = 587.6 nm) of the lens, νd is the lens, etc. The Abbe number with respect to the d line is shown. The surface with * in the surface number indicates an aspherical surface. The sign of the radius of curvature is positive when the convex surface is directed to the object side. In the aspheric coefficient, “E−n” represents “× 10 ⁻ⁿ ”. Further, the focal length f (mm), F number, maximum field angle 2ω (°), maximum image height Ymax (mm), and lens system total length TTL (mm) of the entire imaging lens system are values for the d line. . The same applies to Example 2 and later described later.

(Surface data)
Surface number r d nd νd
(Aperture) 1 INF 0.574
* 2 303.0574 0.799 1.8820 37.2
* 3 -5.2198 0.100
* 4 6.7529 0.556 1.6150 25.9
* 5 2.4845 0.304
* 6 6.1330 1.829 1.5312 56.1
* 7 -2.7754 0.533
* 8 -0.8723 0.674 1.6340 23.9
* 9 -1.6706 0.103
* 10 1.7017 1.200 1.5312 56.1
* 11 2.5534 1.200
12 INF 0.500 1.5168 64.2
13 INF 0.773
(Image plane) 14 INF

(Aspheric data)
Cone coefficient (ε) and aspheric coefficient (B, C, D, E)
ε B C D E
Second side 5.0227 -1.17869E-02 -6.10838E-03 1.89727E-03 -4.98467E-04
3rd surface -1.7207 -1.10850E-02 -4.11435E-03 1.24166E-03 -2.42464E-04
4th surface 2.6194 -3.35486E-02 9.79408E-03 -2.13154E-03 1.53193E-04
5th surface -4.7072 -8.72895E-03 4.14215E-03 -1.03474E-03 8.00742E-05
6th surface -18.3504 1.61208E-03 -8.97521E-04 2.27347E-04 -1.12597E-05
7th surface -4.9510 -1.99238E-02 1.79296E-03 1.79568E-04 -3.03506E-05
8th surface -1.6096 -1.60448E-02 7.09652E-03 -3.99041E-04 -1.78944E-05
9th surface -2.1932 -1.16602E-02 4.81795E-03 -4.65985E-04 2.80754E-05
10th surface -3.8062 -3.99355E-03 -1.47168E-03 9.08503E-05 -4.71381E-07
11th surface -1.1141 -1.02547E-02 1.29758E-04 2.00108E-05 -9.21764E-07

(Various data)
Focal length f (mm) 5.175
F number 2.47
Maximum angle of view 2ω (°) 81.5
Maximum image height Ymax (mm) 4.66
Total length TTL (mm) 8.97 (back focus is air equivalent length)

(Focal length of each lens)
Lens number Start surface Focal length (mm)
L1 2 5.825 (f1)
L2 4 -6.725 (f2)
L3 6 3.873 (f3)
L4 8 -4.282 (f4)
L5 10 6.452 (f5)

(Numerical values related to conditional expression (1))
f / r1f = 0.015

(Numerical value related to conditional expression (2))
L / Ymax = 0.123

(Numerical values related to conditional expression (3))
f2 / f = -1.300

(Numerical values related to conditional expression (4))
f3 / f = 0.748

(Numerical values related to conditional expression (5))
nd_1 = 1.88

(Numerical values related to conditional expression (6))
f4 / f5 = -0.664

(Numerical values related to conditional expression (7))
TTL / (2 × Ymax) = 0.96

(Numerical value for conditional expression (8))
f1 / f = 1.126

(Numerical values related to conditional expression (9))
νd_3 = 56.1

(Numerical values related to conditional expression (10))
f4 / f = -0.827

  FIG. 2 is a longitudinal aberration diagram of the imaging lens according to the first example. In the spherical aberration diagram, Fno represents an F number, and g, F, d, and C are g line (λ = 435.8 nm), F line (λ = 486.1 nm), and d line (λ = 587.6 nm), respectively. ), A characteristic of a wavelength corresponding to the C line (λ = 656.3 nm). In the astigmatism diagram, ω represents a half angle of view, S represents a sagittal direction, and T represents a wavelength characteristic corresponding to the d-line in the tangential direction. In the distortion diagram, ω represents a half angle of view, and the solid line represents a wavelength characteristic corresponding to the d-line.

  FIG. 3 is a cross-sectional view along the optical axis showing the configuration of the imaging lens according to the second example. The optical configuration of the imaging lens according to the present example is the same as that of the imaging lens shown in Example 1. Therefore, in the present embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

  Various numerical data (optical specification table) relating to the imaging lens according to Example 2 are shown below.

(Surface data)
Surface number r d nd νd
(Aperture) 1 INF 0.219
* 2 5.1707 0.799 1.8014 45.5
* 3 -111.450 0.224
* 4 10.9101 0.504 1.6150 25.9
* 5 3.3207 0.321
* 6 7.4319 1.198 1.5312 56.1
* 7 -3.2357 0.544
* 8 -0.8909 0.566 1.6150 25.9
* 9 -1.5237 0.100
* 10 1.6067 1.061 1.5312 56.1
* 11 2.1111 1.151
12 INF 0.500 1.5168 64.2
13 INF 0.773
(Image plane) 14 INF

(Aspheric data)
Cone coefficient (ε) and aspheric coefficient (B, C, D, E)
ε B C D E
Second side 5.9464 -1.55614E-02 -3.04103E-03 -1.74492E-03 2.91607E-04
3rd surface -1.7326 -4.48838E-02 9.56783E-03 -2.91899E-03 4.67811E-04
4th surface 3.3714 -9.29147E-02 4.30053E-02 -8.24191E-03 7.17052E-04
5th surface -0.1003 -6.46671E-02 3.33410E-02 -7.28612E-03 6.30656E-04
6th surface -17.6862 -9.94322E-03 -3.11106E-04 9.01659E-05 7.30772E-05
7th surface -6.3422 -1.78602E-02 2.93080E-03 -3.00820E-04 -3.13211E-06
8th surface -1.8833 -3.48265E-02 1.83100E-02 -2.45004E-03 8.87753E-05
9th surface -1.9805 -2.15554E-02 8.91772E-03 -8.90918E-04 4.56475E-05
10th surface -4.0397 -6.99641E-03 -1.84841E-03 2.00244E-04 -4.80179E-06
11th surface -1.8811 -1.19616E-02 3.95248E-04 5.69834E-07 -4.89788E-07

(Various data)
Focal length f (mm) 5.178
F number 2.48
Maximum angle of view 2ω (°) 81.3
Maximum image height Ymax (mm) 4.66
Total length TTL (mm) 7.77 (back focus is air equivalent length)

(Focal length of each lens)
Lens number Start surface Focal length (mm)
L1 2 6.184 (f1)
L2 4 -7.963 (f2)
L3 6 4.416 (f3)
L4 8 -5.287 (f4)
L5 10 7.320 (f5)

(Numerical values related to conditional expression (1))
f / r1f = 1.0001

(Numerical value related to conditional expression (2))
L / Ymax = 0.047

(Numerical values related to conditional expression (3))
f2 / f = -1.538

(Numerical values related to conditional expression (4))
f3 / f = 0.653

(Numerical values related to conditional expression (5))
nd_1 = 1.80

(Numerical values related to conditional expression (6))
f4 / f5 = -0.722

(Numerical values related to conditional expression (7))
TTL / (2 × Ymax) = 0.83

(Numerical value for conditional expression (8))
f1 / f = 1.194

(Numerical values related to conditional expression (9))
νd_3 = 56.1

(Numerical values related to conditional expression (10))
f4 / f = -1.021

  FIG. 4 is a longitudinal aberration diagram of the imaging lens according to the second example. In the spherical aberration diagram, Fno represents an F number, and g, F, d, and C are g line (λ = 435.8 nm), F line (λ = 486.1 nm), and d line (λ = 587.6 nm), respectively. ), A characteristic of a wavelength corresponding to the C line (λ = 656.3 nm). In the astigmatism diagram, ω represents a half angle of view, S represents a sagittal direction, and T represents a wavelength characteristic corresponding to the d-line in the tangential direction. In the distortion diagram, ω represents a half angle of view, and the solid line represents a wavelength characteristic corresponding to the d-line.

  FIG. 5 is a cross-sectional view along the optical axis showing the configuration of the imaging lens according to the third example. The optical configuration of the imaging lens according to the present example is the same as that of the imaging lens shown in Example 1 except that the first lens L31 is a positive meniscus lens having a convex surface facing the image side. Therefore, in the present embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

  Various numerical data (optical specification table) relating to the imaging lens according to the example 3 will be shown below.

(Surface data)
Surface number r d nd νd
(Aperture) 1 INF 0.535
* 2 -6.5020 0.794 1.7290 54.0
* 3 -2.9247 0.100
* 4 4.0668 0.706 1.6150 25.9
* 5 2.2630 0.415
* 6 7.8630 2.046 1.5312 56.1
* 7 -2.5968 0.500
* 8 -0.8330 0.680 1.6150 25.9
* 9 -1.6502 0.100
* 10 1.6539 1.075 1.5312 56.1
* 11 2.5246 1.185
12 INF 0.500 1.5168 64.2
13 INF 0.772
(Image plane) 14 INF

(Aspheric data)
Cone coefficient (ε) and aspheric coefficient (B, C, D, E)
ε B C D E
2nd surface 5.2357 -1.15445E-02 -6.28611E-03 2.13871E-03 -4.40812E-04
3rd surface -4.2764 -2.00024E-02 -3.40125E-03 1.30429E-03 -1.99289E-04
4th surface 0.5131 -1.55592E-02 2.52713E-03 -4.70919E-04 2.54017E-05
5th surface -4.2838 3.36171E-03 -5.12824E-04 -5.14545E-05 2.51766E-06
6th surface -18.0836 1.66527E-03 1.87829E-05 1.40688E-04 -1.57851E-05
7th surface -3.5598 -1.23346E-02 -1.12590E-03 6.94733E-04 -5.85847E-05
8th surface -1.5345 -2.98971E-03 1.88046E-03 2.84463E-04 -4.58119E-05
9th surface -2.2647 -4.22546E-03 3.23269E-03 -3.56510E-04 2.44531E-05
10th surface -3.5868 -3.57439E-03 -1.60536E-03 1.04612E-04 -5.23501E-07
11th surface -0.7535 -1.26907E-02 2.40749E-04 1.98797E-05 -9.57746E-07

(Various data)
Focal length f (mm) 5.175
F number 2.47
Maximum angle of view 2ω (°) 80.7
Maximum image height Ymax (mm) 4.66
Full length TTL (mm) 9.24 (back focus is air equivalent length)

(Focal length of each lens)
Lens number Start surface Focal length (mm)
L31 2 6.668 (f1)
L2 4 -9.747 (f2)
L3 6 3.943 (f3)
L4 8 -4.003 (f4)
L5 10 6.321 (f5)

(Numerical values related to conditional expression (1))
f / r1f = -0.796

(Numerical value related to conditional expression (2))
L / Ymax = 0.115

(Numerical values related to conditional expression (3))
f2 / f = -1.883

(Numerical values related to conditional expression (4))
f3 / f = 0.762

(Numerical values related to conditional expression (5))
nd_1 = 1.73

(Numerical values related to conditional expression (6))
f4 / f5 = -0.633

(Numerical values related to conditional expression (7))
TTL / (2 × Ymax) = 0.99

(Numerical value for conditional expression (8))
f1 / f = 1.288

(Numerical values related to conditional expression (9))
νd_3 = 56.1

(Numerical values related to conditional expression (10))
f4 / f = -0.774

  FIG. 6 is a longitudinal aberration diagram of the imaging lens according to the third example. In the spherical aberration diagram, Fno represents an F number, and g, F, d, and C are g line (λ = 435.8 nm), F line (λ = 486.1 nm), and d line (λ = 587.6 nm), respectively. ), A characteristic of a wavelength corresponding to the C line (λ = 656.3 nm). In the astigmatism diagram, ω represents a half angle of view, S represents a sagittal direction, and T represents a wavelength characteristic corresponding to the d-line in the tangential direction. In the distortion diagram, ω represents a half angle of view, and the solid line represents a wavelength characteristic corresponding to the d-line.

  FIG. 7 is a cross-sectional view along the optical axis showing the configuration of the imaging lens according to the fourth example. The optical configuration of the imaging lens according to the present example is the same as that of the imaging lens shown in Example 1. Therefore, in the present embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

  Various numerical data (optical specification table) relating to the imaging lens according to Example 4 will be shown below.

(Surface data)
Surface number r d nd νd
(Aperture) 1 INF 0.899
* 2 9.4135 0.987 1.8514 40.1
* 3 -16.4390 0.100
* 4 5.2590 0.505 1.6150 25.9
* 5 2.5926 0.307
* 6 5.4762 1.521 1.5312 56.1
* 7 -3.2913 0.620
* 8 -0.8606 0.722 1.6340 23.9
* 9 -1.6953 0.100
* 10 1.6719 1.176 1.5312 56.1
* 11 2.8355 1.191
12 INF 0.500 1.5168 64.2
13 INF 0.774
(Image plane) 14 INF

(Aspheric data)
Cone coefficient (ε) and aspheric coefficient (B, C, D, E)
ε B C D E
Second side 5.4901 -6.69952E-03 -5.06209E-03 1.01159E-03 -3.19463E-04
3rd surface -2.1946 -2.47398E-02 -1.01969E-03 5.75713E-04 -1.33992E-04
4th surface 1.4351 -5.92213E-02 1.39957E-02 -2.24918E-03 1.75763E-04
5th surface -3.5167 -2.66770E-02 1.09599E-02 -2.10858E-03 1.44685E-04
6th surface -17.9463 -1.37678E-03 -1.43594E-03 4.13264E-04 -2.09397E-05
7th surface -5.9974 -7.08994E-03 3.17959E-05 3.31009E-04 -3.99561E-05
8th -1.6211 -1.50671E-02 8.88848E-03 -8.06843E-04 1.78866E-06
9th surface -2.3944 -1.74399E-02 6.60888E-03 -6.53077E-04 3.50831E-05
10th surface -3.5714 -3.16332E-03 -9.70669E-04 4.23315E-05 6.09116E-07
11th surface -0.9329 -8.72642E-03 1.70950E-05 1.95831E-05 -8.28579E-07

(Various data)
Focal length f (mm) 5.308
F number 2.47
Maximum angle of view 2ω (°) 77.8
Maximum image height Ymax (mm) 4.66
Total length TTL (mm) 9.23 (back focus is air equivalent length)

(Focal length of each lens)
Lens number Start surface Focal length (mm)
L1 2 7.157 (f1)
L2 4 -8.960 (f2)
L3 6 4.118 (f3)
L4 8 -4.148 (f4)
L5 10 5.680 (f5)

(Numerical values related to conditional expression (1))
f / r1f = 0.564

(Numerical value related to conditional expression (2))
L / Ymax = 0.193

(Numerical values related to conditional expression (3))
f2 / f = -1.688

(Numerical values related to conditional expression (4))
f3 / f = 0.76

(Numerical values related to conditional expression (5))
nd_1 = 1.85

(Numerical values related to conditional expression (6))
f4 / f5 = -0.730

(Numerical values related to conditional expression (7))
TTL / (2 × Ymax) = 0.99

(Numerical value for conditional expression (8))
f1 / f = 1.348

(Numerical values related to conditional expression (9))
νd_3 = 56.1

(Numerical values related to conditional expression (10))
f4 / f = -0.781

  FIG. 8 is a longitudinal aberration diagram of the imaging lens according to the fourth example. In the spherical aberration diagram, Fno represents an F number, and g, F, d, and C are g line (λ = 435.8 nm), F line (λ = 486.1 nm), and d line (λ = 587.6 nm), respectively. ), A characteristic of a wavelength corresponding to the C line (λ = 656.3 nm). In the astigmatism diagram, ω represents a half angle of view, S represents a sagittal direction, and T represents a wavelength characteristic corresponding to the d-line in the tangential direction. In the distortion diagram, ω represents a half angle of view, and the solid line represents a wavelength characteristic corresponding to the d-line.

  FIG. 9 is a cross-sectional view along the optical axis showing the configuration of the imaging lens according to the fifth example. The optical configuration of the imaging lens according to the present example is the same as that of the imaging lens shown in Example 1 except that the second lens L52 is a biconcave negative lens. Therefore, in the present embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

  Various numerical data (optical specification table) relating to the imaging lens according to Example 5 will be shown below.

(Surface data)
Surface number r d nd νd
(Aperture) 1 INF 0.329
* 2 316.4880 1.487 1.8820 37.2
* 3 -3.1622 0.100
* 4 -34.5956 0.500 1.6150 25.9
* 5 2.4912 0.297
* 6 7.9936 1.721 1.5312 56.1
* 7 -2.8121 0.776
* 8 -0.8636 0.550 1.6150 25.9
* 9 -1.5332 0.224
* 10 1.8033 1.054 1.5312 56.1
* 11 2.8016 1.105
12 INF 0.500 1.5168 64.2
13 INF 0.769
(Image plane) 14 INF

(Aspheric data)
Cone coefficient (ε) and aspheric coefficient (B, C, D, E)
ε B C D E
Second side 5.0225 -9.40839E-03 -2.43851E-03 3.13733E-04 -1.31898E-04
3rd surface -11.4996 -1.91270E-02 -1.01125E-03 4.08167E-04 -6.32415E-05
4th surface 2.1570 -4.91373E-03 -4.47066E-03 8.33469E-04 -6.66199E-05
5th surface -8.9795 4.06910E-03 -1.41112E-03 6.34172E-05 -4.47410E-06
6th surface -18.6725 -3.48290E-03 1.57508E-03 -9.30910E-05 2.08003E-07
7th surface -2.4581 -6.99281E-03 -2.72523E-03 1.11137E-03 -9.03601E-05
8th surface -1.4370 -1.72973E-02 6.34831E-03 -2.43235E-04 -2.52333E-05
9th surface -1.8372 -1.50133E-02 5.43122E-03 -6.40679E-04 4.05213E-05
10th surface -4.4660 -6.44067E-03 -9.35552E-04 1.13352E-06 3.31400E-06
11th surface -1.4549 -8.35276E-03 -9.43920E-05 2.72984E-05 -9.86299E-07

(Various data)
Focal length f (mm) 5.283
F number 2.47
Maximum angle of view 2ω (°) 81.0
Maximum image height Ymax (mm) 4.66
Full length TTL (mm) 9.24 (back focus is air equivalent length)

(Focal length of each lens)
Lens number Start surface Focal length (mm)
L1 2 3.557 (f1)
L52 4 -3.759 (f2)
L3 6 4.146 (f3)
L4 8 -4.679 (f4)
L5 10 6.974 (f5)

(Numerical values related to conditional expression (1))
f / r1f = 0.015

(Numerical value related to conditional expression (2))
L / Ymax = 0.071

(Numerical values related to conditional expression (3))
f2 / f = -0.712

(Numerical values related to conditional expression (4))
f3 / f = 0.785

(Numerical values related to conditional expression (5))
nd_1 = 1.88

(Numerical values related to conditional expression (6))
f4 / f5 = -0.671

(Numerical values related to conditional expression (7))
TTL / (2 × Ymax) = 0.99

(Numerical value for conditional expression (8))
f1 / f = 0.673

(Numerical values related to conditional expression (9))
νd_3 = 56.1

(Numerical values related to conditional expression (10))
f4 / f = -0.886

  FIG. 10 is a longitudinal aberration diagram of the imaging lens according to the fifth example. In the spherical aberration diagram, Fno represents an F number, and g, F, d, and C are g line (λ = 435.8 nm), F line (λ = 486.1 nm), and d line (λ = 587.6 nm), respectively. ), A characteristic of a wavelength corresponding to the C line (λ = 656.3 nm). In the astigmatism diagram, ω represents a half angle of view, S represents a sagittal direction, and T represents a wavelength characteristic corresponding to the d-line in the tangential direction. In the distortion diagram, ω represents a half angle of view, and the solid line represents a wavelength characteristic corresponding to the d-line.

  FIG. 11 is a cross-sectional view along the optical axis showing the configuration of the imaging lens according to the sixth example. The optical configuration of the imaging lens according to the present example is the same as that of the imaging lens shown in Example 1. Therefore, in the present embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Various numerical data (optical specification table) relating to the imaging lens according to Example 6 will be described below.

(Surface data)
Surface number r d nd νd
(Aperture) 1 INF 0.413
* 2 437.9658 0.729 1.8820 37.2
* 3 -6.9936 0.155
* 4 5.3600 0.523 1.6150 25.9
* 5 2.4618 0.245
* 6 4.5025 1.906 1.5312 56.1
* 7 -2.5429 0.491
* 8 -0.8497 0.769 1.6150 25.9
* 9 -1.8399 0.166
* 10 1.7224 1.333 1.5312 56.1
* 11 2.8640 1.175
12 INF 0.500 1.5168 64.2
13 INF 0.770
(Image plane) 14 INF

(Aspheric data)
Cone coefficient (ε) and aspheric coefficient (B, C, D, E)
ε B C D E
Second side 5.0227 -1.01769E-02 -4.69134E-03 2.71177E-04 -2.67236E-04
3rd surface -1.6997 -9.91171E-03 -6.15050E-03 4.11021E-04 -4.76034E-05
4th surface 1.3429 -3.04238E-02 6.05292E-03 -3.14179E-03 3.81083E-04
5th surface -5.2944 -6.77294E-03 2.86208E-03 -1.23682E-03 1.34389E-04
6th surface -14.4858 2.28252E-04 -2.03765E-03 3.63596E-04 -2.09532E-06
7th surface -5.8469 -2.38801E-02 2.24048E-03 5.94649E-05 -1.82104E-05
8th surface -1.5918 -1.87250E-02 8.84427E-03 -6.87977E-04 -4.90622E-06
9th surface -2.9783 -1.98718E-02 7.38306E-03 -8.29887E-04 4.50237E-05
10th surface -3.6664 -5.48626E-03 -7.29406E-04 -1.19947E-05 3.20453E-06
11th surface -1.1769 -7.58711E-03 -1.11550E-04 2.78410E-05 -1.00790E-06

(Various data)
Focal length f (mm) 5.175
F number 2.47
Maximum angle of view 2ω (°) 80.9
Maximum image height Ymax (mm) 4.66
Full length TTL (mm) 9.01 (back focus is air equivalent length)

(Focal length of each lens)
Lens number Start surface Focal length (mm)
L1 2 7.810 (f1)
L2 4 -7.949 (f2)
L3 6 3.376 (f3)
L4 8 -3.646 (f4)
L5 10 5.790 (f5)

(Numerical values related to conditional expression (1))
f / r1f = 0.012

(Numerical value related to conditional expression (2))
L / Ymax = 0.089

(Numerical values related to conditional expression (3))
f2 / f = -1.536

(Numerical values related to conditional expression (4))
f3 / f = 0.552

(Numerical values related to conditional expression (5))
nd_1 = 1.88

(Numerical values related to conditional expression (6))
f4 / f5 = -0.630

(Numerical values related to conditional expression (7))
TTL / (2 × Ymax) = 0.97

(Numerical value for conditional expression (8))
f1 / f = 1.509

(Numerical values related to conditional expression (9))
νd_3 = 56.1

(Numerical values related to conditional expression (10))
f4 / f = -0.705

  FIG. 12 is a longitudinal aberration diagram of the imaging lens according to the sixth example. In the spherical aberration diagram, Fno represents an F number, and g, F, d, and C are g line (λ = 435.8 nm), F line (λ = 486.1 nm), and d line (λ = 587.6 nm), respectively. ), A characteristic of a wavelength corresponding to the C line (λ = 656.3 nm). In the astigmatism diagram, ω represents a half angle of view, S represents a sagittal direction, and T represents a wavelength characteristic corresponding to the d-line in the tangential direction. In the distortion diagram, ω represents a half angle of view, and the solid line represents a wavelength characteristic corresponding to the d-line.

  FIG. 13 is a cross-sectional view along the optical axis showing the configuration of the imaging lens according to the seventh example. The optical configuration of the imaging lens according to the present example is the same as that of the imaging lens shown in Example 3. Therefore, in the present embodiment, the same members as those in the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Various numerical data (optical specification table) relating to the imaging lens according to Example 7 are shown below.

(Surface data)
Surface number r d nd νd
(Aperture) 1 INF 0.363
* 2 -17.2416 0.822 1.7290 54.0
* 3 -3.2091 0.100
* 4 3.9955 0.512 1.6150 25.9
* 5 2.1936 0.504
* 6 11.7592 1.420 1.5312 56.1
* 7 -4.4168 0.621
* 8 -0.9446 0.551 1.6567 21.2
* 9 -1.5750 0.100
* 10 1.7102 1.221 1.5312 56.1
* 11 2.5354 1.063
12 INF 0.500 1.5168 64.2
13 INF 0.770
(Image plane) 14 INF

(Aspheric data)
Cone coefficient (ε) and aspheric coefficient (B, C, D, E)
ε B C D E
2nd surface 3.4716 -2.25582E-02 -5.16750E-03 -2.35321E-04 -2.15083E-04
3rd surface -8.8078 -3.42999E-02 -1.38767E-03 5.21917E-04 -2.06711E-04
4th surface -12.8593 1.35635E-02 -9.24744E-03 2.07179E-03 -1.83133E-04
5th surface -5.9542 2.67447E-02 -1.09143E-02 2.06168E-03 -1.87628E-04
6th surface -1.0794 -6.94324E-03 5.80197E-03 -6.89011E-04 2.27079E-05
7th surface 2.0700 -2.15949E-03 -1.73555E-03 1.75331E-03 -1.85310E-04
8th surface -1.8198 -1.29121E-02 5.42832E-03 5.71527E-04 -1.43129E-04
9th surface -1.3587 2.10908E-03 1.61640E-03 8.60299E-06 1.48278E-05
10th surface -4.5102 -5.97126E-03 -1.69492E-03 1.19717E-04 4.88238E-07
11th surface -2.6137 -8.20986E-03 -7.75764E-05 3.45985E-05 -1.47621E-06

(Various data)
Focal length f (mm) 5.172
F number 2.47
Maximum angle of view 2ω (°) 80.9
Maximum image height Ymax (mm) 4.66
Total length TTL (mm) 8.38 (back focus is air equivalent length)

(Focal length of each lens)
Lens number Start surface Focal length (mm)
L31 2 5.278 (f1)
L2 4 -8.869 (f2)
L3 6 6.235 (f3)
L4 8 -5.500 (f4)
L5 10 6.536 (f5)

(Numerical values related to conditional expression (1))
f / r1f = -0.300

(Numerical value related to conditional expression (2))
L / Ymax = 0.078

(Numerical values related to conditional expression (3))
f2 / f = -1.715

(Numerical values related to conditional expression (4))
f3 / f = 1.206

(Numerical values related to conditional expression (5))
nd_1 = 1.73

(Numerical values related to conditional expression (6))
f4 / f5 = -0.841

(Numerical values related to conditional expression (7))
TTL / (2 × Ymax) = 0.90

(Numerical value for conditional expression (8))
f1 / f = 1.020

(Numerical values related to conditional expression (9))
νd_3 = 56.1

(Numerical values related to conditional expression (10))
f4 / f = -1.063

  FIG. 14 is a longitudinal aberration diagram of the imaging lens according to the seventh example. In the spherical aberration diagram, Fno represents an F number, and g, F, d, and C are g line (λ = 435.8 nm), F line (λ = 486.1 nm), and d line (λ = 587.6 nm), respectively. ), A characteristic of a wavelength corresponding to the C line (λ = 656.3 nm). In the astigmatism diagram, ω represents a half angle of view, S represents a sagittal direction, and T represents a wavelength characteristic corresponding to the d-line in the tangential direction. In the distortion diagram, ω represents a half angle of view, and the solid line represents a wavelength characteristic corresponding to the d-line.

  FIG. 15 is a cross-sectional view along the optical axis showing the configuration of the imaging lens according to the eighth example. The optical configuration of the imaging lens according to the present example is shown in Example 1 except that the fourth lens L84 is a positive meniscus lens having a concave surface facing the object side, and the final lens L85 has a negative refractive power. This is the same as the imaging lens. Similarly to the final lens L5 of Example 1, the final lens L85 also has an aspheric image side surface, and has extreme values at positions other than the intersection of the aspheric surface and the optical axis. Although the shape has a concave surface, the periphery of the optical effective diameter has a shape with a convex surface facing the image side. In the present embodiment, members similar to those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Hereinafter, various numerical data (optical specification table) relating to the imaging lens according to Example 8 will be shown.

(Surface data)
Surface number r d nd νd
(Aperture) 1 INF 0.600
* 2 171.3591 0.897 1.8014 45.5
* 3 -4.4139 0.182
* 4 21.2223 0.500 1.6150 25.9
* 5 3.0065 0.299
* 6 5.4642 1.320 1.5312 56.1
* 7 -9.7867 0.521
* 8 -2.4430 1.341 1.5312 56.1
* 9 -1.4191 0.100
* 10 2.4763 0.712 1.6397 23.5
* 11 1.2386 1.389
12 INF 0.500 1.5168 64.2
13 INF 0.772
(Image plane) 14 INF

(Aspheric data)
Cone coefficient (ε) and aspheric coefficient (B, C, D, E)
ε B C D E
2nd surface 5.1351 -1.62483E-02 -5.90497E-03 1.03419E-03 -3.19885E-04
3rd surface 2.5336 -1.71586E-02 7.40693E-04 8.97956E-05 -1.22707E-04
4th surface -9.7009 -4.46553E-02 1.91554E-02 -3.85068E-03 2.74469E-04
5th surface -7.4955 -1.56774E-02 7.75812E-03 -1.51002E-03 9.78936E-05
6th surface 0.2428 -1.51721E-02 1.17343E-03 -4.10569E-05 9.40896E-06
7th surface -4.3849 -1.12736E-02 1.42717E-03 -2.77635E-04 2.37769E-05
8th surface -3.9731 -3.49554E-02 1.08980E-02 -9.15819E-04 2.48490E-05
9th surface -2.1055 -2.52461E-02 4.84850E-03 -1.90995E-04 7.47320E-06
10th surface -5.1007 -6.49922E-03 -5.52709E-04 3.08478E-05 -1.06367E-06
11th surface -2.9362 -7.54555E-03 1.40775E-04 6.85976E-06 -4.58967E-07

(Various data)
Focal length f (mm) 5.175
F number 2.47
Maximum angle of view 2ω (°) 84.2
Maximum image height Ymax (mm) 4.66
Total length TTL (mm) 8.96 (back focus is air equivalent length)

(Focal length of each lens)
Lens number Start surface Focal length (mm)
L1 2 5.382 (f1)
L2 4 -5.756 (f2)
L3 6 6.806 (f3)
L84 8 4.384 (f4)
L85 10 -4.995 (f5)

(Numerical values related to conditional expression (1))
f / r1f = 0.030

(Numerical value related to conditional expression (2))
L / Ymax = 0.129

(Numerical values related to conditional expression (3))
f2 / f = -1.113

(Numerical values related to conditional expression (4))
f3 / f = 1.316

(Numerical values related to conditional expression (5))
nd_1 = 1.80

(Numerical values related to conditional expression (6))
f4 / f5 = -0.878

(Numerical values related to conditional expression (7))
TTL / (2 × Ymax) = 0.96

(Numerical value for conditional expression (8))
f1 / f = 1.040

(Numerical values related to conditional expression (9))
νd_3 = 56.1

(Numerical values related to conditional expression (10))
f4 / f = 0.847

  FIG. 16 is a longitudinal aberration diagram of the imaging lens according to the eighth example. In the spherical aberration diagram, Fno represents an F number, and g, F, d, and C are g line (λ = 435.8 nm), F line (λ = 486.1 nm), and d line (λ = 587.6 nm), respectively. ), A characteristic of a wavelength corresponding to the C line (λ = 656.3 nm). In the astigmatism diagram, ω represents a half angle of view, S represents a sagittal direction, and T represents a wavelength characteristic corresponding to the d-line in the tangential direction. In the distortion diagram, ω represents a half angle of view, and the solid line represents a wavelength characteristic corresponding to the d-line.

  The correspondence table of the conditional expressions in the above embodiments is shown below.

Example 1 Example 2 Example 3 Example 4
(1) f / r1f 0.017 1.001 -0.796 0.564
(2) L / Ymax 0.123 0.047 0.115 0.193
(3) f2 / f -1.300 -1.538 -1.883 -1.688
(4) f3 / f 0.748 0.853 0.762 0.776
(5) nd_1 1.88 1.80 1.73 1.85
(6) f4 / f5 -0.664 -0.722 -0.633 -0.730
(7) TTL / (2 × Ymax) 0.96 0.83 0.99 0.99
(8) f1 / f 1.126 1.194 1.288 1.348
(9) νd — 3 56.1 56.1 56.1 56.1
(10) f4 / f -0.827 -1.021 -0.774 -0.781

Example 5 Example 6 Example 7 Example 8
(1) f / r1f 0.017 0.012 -0.300 0.030
(2) L / Ymax 0.071 0.089 0.078 0.129
(3) f2 / f -0.712 -1.536 -1.715 -1.113
(4) f3 / f 0.785 0.652 1.206 1.316
(5) nd_1 1.88 1.88 1.73 1.80
(6) f4 / f5 -0.671 -0.630 -0.841 -0.878
(7) TTL / (2 × Ymax) 0.99 0.97 0.90 0.96
(8) f1 / f 0.673 1.509 1.020 1.040
(9) νd — 3 56.1 56.1 56.1 56.1
(10) f4 / f -0.886 -0.705 -1.063 0.847

  Each of the aspherical shapes has a vertex at the surface as the origin, the coordinate in the direction perpendicular to the optical axis is H, the amount of displacement in the optical axis direction at H is X (H), the paraxial radius of curvature is R, the cone coefficient is ε When the fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients are B, C, D, and E, respectively, and the displacement in the image plane direction is positive, they are expressed by the following equations. The sign of the surface shape and refractive power is considered in the paraxial region when an aspheric surface is included. Further, in each of the above embodiments, the aspheric shape having an extreme value means that the value of X (H) has a point where the value changes from increase to decrease, or a point where the value changes from decrease to increase. .

  As described above, the imaging lens of each of the above embodiments has a diaphragm unit having a movable part near the diaphragm, such as a variable diaphragm that can change the size of the diaphragm diameter by satisfying each conditional expression. Even when the lens unit is mounted in the lens system, it is possible to reduce the lens radial direction and total length in the lens unit including mechanical parts and the like, and to provide a high resolution with a wide angle of view. In addition, the ability to correct aberrations can be improved by arranging a lens having an aspheric surface as appropriate.

<Application example>
Hereinafter, the example which applied the imaging lens concerning the present invention to an imaging device is shown. FIG. 17 is a diagram illustrating an application example of an imaging apparatus including the imaging lens according to the present invention. As illustrated in FIG. 17, the imaging apparatus 200 includes an imaging lens 100 and an imaging element 201. In FIG. 17, the imaging lens 100 described in the first embodiment is described (see FIG. 1), but the imaging lenses of the second to eighth embodiments are also applicable.

  In the imaging apparatus 200 including the imaging lens 100 and the imaging element 201, the image plane IMG shown in the first embodiment corresponds to the imaging plane 201a of the imaging element 201. As the image sensor 201, for example, a photoelectric conversion element such as a CCD or a CMOS sensor can be used.

  In the imaging apparatus 200, the light incident from the object side of the imaging lens 100 finally forms an image on the imaging surface 201 a of the imaging element 201. Then, the light received by the image sensor 201 is photoelectrically converted and output as an electrical signal. This output signal is processed by a signal processing circuit (not shown) to generate a digital image corresponding to the image of the subject. The digital image can be recorded on a recording medium such as an HDD (Hard Disk Drive), a memory card, an optical disk, or a magnetic tape. When the imaging device 200 is a silver salt film camera, the imaging surface 201a corresponds to a film surface.

  As described above, by providing the imaging lens 100, it is possible to realize the imaging device 200 that is small and has a wide field angle and a high resolution.

  As described above, the imaging lens according to the present invention is useful for an imaging apparatus that is small and has a wide angle of view and requires high resolution.

DESCRIPTION OF SYMBOLS 100 Imaging lens 200 Imaging device 201 Imaging element 201a Imaging surface L1, L31 1st lens L2, L52 2nd lens L3 3rd lens L4, L84 4th lens L5, L85 Final lens STOP Aperture stop CG Cover glass IMG Image surface

Claims (9)

An aperture stop, a first lens having a positive refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power, which are arranged in order from the object side,
On the most image side, the image-side surface has an aspherical shape, and a final lens having a shape having an extreme value at a position other than the intersection of the aspherical surface and the optical axis is disposed,
An imaging lens characterized by satisfying the following conditional expression:
(1) -2.81 ≦ f / r1f ≦ 1.65
(2) 0.042 ≦ L / Ymax ≦ 0.830
Where f is the focal length of the entire imaging lens system, r1f is the paraxial radius of curvature of the object side surface of the first lens, L is the distance on the optical axis from the aperture stop to the object side surface of the first lens, and Ymax. Indicates the maximum image height of the imaging lens.   The imaging lens according to claim 1, wherein the second lens has a shape with a concave surface facing the image side. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
(3) −10.0 ≦ f2 / f ≦ −0.55
Here, f2 represents the focal length of the second lens. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
(4) 0.45 ≦ f3 / f ≦ 2.00
Here, f3 represents the focal length of the third lens. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
(5) nd_1 ≧ 1.58
Here, nd_1 represents the refractive index with respect to the d-line of the first lens.   The imaging lens according to claim 1, wherein a fourth lens having a negative refractive power is disposed between the third lens and the final lens. The imaging lens according to claim 6, wherein the following conditional expression is satisfied.
(6) -1.30 ≦ f4 / f5 ≦ −0.15
Here, f4 represents the focal length of the fourth lens, and f5 represents the focal length of the final lens. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
(7) TTL / (2 × Ymax) ≦ 1.5
Note that TTL represents the distance on the optical axis from the object side surface of the first lens to the image plane (the back focus portion is the air equivalent length).   An imaging apparatus comprising: the imaging lens according to claim 1; and an imaging element that converts an optical image formed by the imaging lens into an electrical signal.

Images