JP2006098976A - Imaging lens and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide imaging lenses capable of achieving a high optical performance while various aberrations are satisfactorily corrected and their miniaturization and thinning are achieved, and an imaging device having such imaging lenses. <P>SOLUTION: The imaging lenses are so composed that an aperture diaphragm, a biconvex first lens L1 having a positive refractive power, a meniscus second lens L2 having a negative refractive power with its concave surface facing the object side, and a meniscus third lens L3 with its convex surface facing the object side are arranged in the order from the object side to the image side. The conditional expression: -1.2<r1/r2<-0.5 is satisfied when the r1 denotes the paraxial curvature radius of the surface of the first lens L1 on the object side, and the r2 denotes the paraxial curvature radius of the surface on the image side. The imaging device is equipped with the imaging lenses and an image pickup device with its imaging surface disposed on the image plane of the imaging lenses. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging lens suitable for use in combination with an imaging element and an imaging apparatus having the imaging lens.

  2. Description of the Related Art Conventionally, various information devices including an imaging device configured using an imaging device such as a solid-state imaging device (for example, a CCD) have been proposed. Such information equipment is configured as, for example, a so-called digital camera or mobile phone device. An image pickup apparatus used in such information equipment includes an image pickup element and an image pickup lens that forms an image of an object (subject) on an image pickup surface of the image pickup element.

  In this imaging apparatus, as the number of pixels in the imaging element is increased and the density is increased, the imaging lens is required to have high optical performance including high resolution.

  In addition, in an imaging apparatus used in a small information device particularly suitable for carrying, an imaging lens is required to be small and thin.

  Thus, in order to realize an imaging lens that has high optical performance and is reduced in size and thickness, a three-lens configuration is employed rather than a two-lens configuration. It is known to be promising. It is also known that high optical performance can be maintained by appropriately adopting a lens having an aspherical surface. For example, Patent Documents 1 to 4 describe a three-lens imaging lens having an aperture-positive-negative-positive refractive power arrangement in order from the object side to the image side.

Japanese Patent Laid-Open No. 2004-4466 JP-A-2004-219807 JP 2004-226487 A JP 2004-240063 A

  However, in the imaging lenses described in Patent Documents 1 to 4, it is difficult to achieve high optical specifications and performance that have been required in recent years.

  That is, the inventor of the present application normalizes the maximum image height by 2.5 mm for these conventional imaging lenses, and uses MTF (Modulation Transfer Function) in the vicinity of the focal position for spatial frequencies of 150 lp / mm (linepair / mm) to 200 lp / mm. : Transfer function) peak value and MTF change characteristics in the optical axis direction were confirmed. MTF is one of the performance evaluation methods of an optical system, and represents the degree of modulation (contrast) in an image when an object having a single spatial frequency is imaged through the optical system.

  Here, the reason why the maximum image height is normalized to 2.5 mm and the spatial frequency is set to 150 lp / mm to 200 lp / mm is as follows.

  That is, assuming that the maximum image height of 2.5 mm is half of the diagonal length of the solid-state image sensor (distance from the optical axis to the corner of the solid-state image sensor), and the aspect ratio of the solid-state image sensor is 3: 4 (horizontally long). The vertical length of the solid-state imaging device is 3 mm. Here, when the number of pixels of the solid-state imaging device is about 2 million pixels, the number of pixels in the vertical direction of the solid-state imaging device is about 1200 pixels, so that the optical performance of the imaging lens is a resolution of 1200 TV lines or more. It is necessary to have a resolution of 900 TV lines or more which is 75% of at least 1200 TV lines. Since 900 TV lines at 3 mm correspond to a spatial frequency of 150 lp / mm and 1200 TV lines at 3 mm correspond to a spatial frequency of 200 lp / mm, the optical performance of an imaging lens with a maximum image height of 2.5 mm is a spatial frequency of 150 lp / mm to 200 lp. The MTF for / mm is important.

  Therefore, in order to evaluate whether the imaging lens has the optical performance required in combination with a solid-state imaging device with high pixels and high density, an MTF with a spatial frequency of 150 lp / mm to 200 lp / mm is used. confirmed.

  As a result of this confirmation, in the above-described conventional imaging lens, except for Example 7 of Patent Document 1, various aberrations (spherical aberration, coma aberration, astigmatism, chromatic aberration, etc.) remain, and thus the focal point. It has been found that the MTF peak value in the vicinity of the position is not sufficiently high, and the MTF peak position for each image height does not match in the optical axis direction.

  In Example 7 of Patent Document 1, the F value representing the brightness of the imaging lens is 4.15, and it cannot be said that the specification of recent imaging lenses that require an F value of about 3 or less is not satisfied. . Further, when Example 7 of Patent Document 1 was used at an F value of about 3, it was found that various aberrations remain and the optical performance is not sufficient.

  That is, it is difficult for the above-described conventional imaging lens to realize high optical specifications and performance that have been required in recent years.

  Therefore, the present invention is proposed in view of the above-described circumstances, and various aberrations are favorably corrected and high optical specifications and performance can be realized while reducing size and thickness. An object of the present invention is to provide a lens and an imaging apparatus having such an imaging lens.

  In order to solve the above-described problems, an imaging lens according to the present invention has the following configuration.

[Configuration 1]
In order from the object side to the image side, an aperture stop, a first biconvex lens having positive refractive power, a second meniscus lens having negative refractive power and a concave surface facing the object side, and A third meniscus lens having a convex surface facing the object side, and at least one of the surfaces of each lens is an aspherical surface. When the paraxial radius of curvature is r1, and the paraxial radius of curvature of the image side surface of the first lens is r2, the following conditional expression (1) is satisfied.
−1.2 <r1 / r2 <−0.5 Formula (1)

[Configuration 2]
In the imaging lens having the configuration 1, at least one of the first to third lenses is an aspherical surface.

[Configuration 3]
In the imaging lens having [Configuration 1] or [Configuration 2], the third lens has a positive refractive power.

[Configuration 4]
In the imaging lens having any one of [Configuration 1] to [Configuration 3], when the focal length of the third lens is f3 and the focal length of the entire imaging lens system is f, the following conditional expression (2) is satisfied. It is characterized by that.
0.5 <f3 / f <6 Formula (2)

[Configuration 5]
In the imaging lens having any one of [Configuration 1] to [Configuration 4], when the focal length of the first lens is f1 and the focal length of the entire imaging lens system is f, the following conditional expression (3) is satisfied: It is characterized by being.
0 <f1 / f <0.7 Formula (3)

[Configuration 6]
In the imaging lens having any one of [Configuration 1] to [Configuration 5], the following conditional expression (4) is satisfied.
−1.2 <r1 / r2 <−0.9 Formula (4)

  In these [Configuration 1] to [Configuration 6], the refractive power, the convex and concave portions of the surface shape are due to the paraxial curvature.

  The imaging device according to the present invention has the following configuration.

[Configuration 7]
An image pickup lens having any one of [Configuration 1] to [Configuration 6] and an image pickup element having an image pickup surface arranged on an image plane of the image pickup lens are provided.

  By having the above [Configuration 1], the present invention can provide a small imaging lens that is bright, has a wide angle of view, and has high resolution. This imaging lens has an optical performance suitable for use in combination with a small imaging device with a high pixel density and high density.

  Moreover, this invention can provide the imaging lens by which various aberrations were favorably corrected by having [Configuration 2].

  Further, according to the present invention having [Configuration 3], the incident angle of the off-axis light beam on the image plane can be reduced and the exit pupil position can be moved away from the image plane. That is, this imaging lens can secure an exit pupil position far from the image plane required from the characteristics of the solid-state imaging device, and has preferable characteristics as an imaging lens used in combination with the solid-state imaging device.

  Furthermore, the present invention can further reduce the incident angle of off-axis rays to the image plane by having [Configuration 4], and has more preferable characteristics as an imaging lens used in combination with a solid-state imaging device. It is.

  Furthermore, according to the present invention having [Configuration 5], it is easier to achieve the required reduction in size and thickness and correction of various aberrations, and a small imaging lens having high resolution can be provided.

  Furthermore, according to the present invention having [Configuration 6], various aberrations can be corrected more easily, and a small imaging lens having high resolution can be provided.

  The imaging lens according to the present invention, for example, normalizes the maximum image height at 2.5 mm, and for the spatial frequency of 150 lp / mm to 200 lp / mm, the MTF (Modulation Transfer Function) peak value and MTF near the focal position. When the change characteristics in the optical axis direction are confirmed, the various values of aberration (spherical aberration, coma aberration, astigmatism, chromatic aberration, etc.) are corrected well, and the MTF peak value near the focal position is sufficiently high. Also, the peak positions of the MTFs for the respective image heights are in good agreement in the optical axis direction.

  In this imaging lens, an exit pupil position far from the image plane can be secured, so that a small imaging device can be configured in combination with a solid-state imaging device.

  In addition, since the present invention has [Configuration 7], various aberrations in the imaging lens are favorably corrected, and an exit pupil position far from the image plane is secured, so a solid-state imaging device is used as the imaging device. Thus, a small-sized and high-performance imaging device can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a configuration of an imaging lens according to the present invention.

  As shown in FIG. 1, the photographing lens according to the present invention has an aperture stop S, a biconvex first lens L1 having a positive refractive power, and a negative refractive power in order from the object side to the image side. And a meniscus second lens L2 having a concave surface facing the object side and a meniscus third lens L3 having a convex surface facing the object side.

  For example, an image pickup surface of an image pickup element is disposed on the image plane of the image pickup lens. As described above, an imaging device is configured by the imaging lens and the imaging element in which the imaging surface is positioned on the image plane of the imaging lens.

  In this imaging apparatus, a filter 1 made of a plane-parallel plate is disposed between the third lens L3 of the imaging lens and the image plane. This filter 1 is an infrared cut filter for preventing the incidence of infrared rays on the image sensor, a low-pass filter for preventing the occurrence of moire fringes, a cover glass of the image sensor, or the like alone or Are arranged in combination. In addition, when arrange | positioning combining these various filters as the filter 1, you may arrange | position each filter through the air layer mutually, and may arrange | position each filter mutually joined.

  In this imaging lens, the first lens L1 has a positive refractive power, and the total length of the lens can be reduced by appropriately increasing the refractive power of L1.

  Further, by disposing the aperture stop S in front of L1 having a positive refractive power, it is possible to reduce the incident angle of the off-axis ray to the image plane and to move the exit pupil position away from the image plane.

  Further, since the second lens L2 has a negative refractive power, various aberrations, particularly Petzval sum can be corrected well. Since the second lens L2 has a meniscus shape with the concave surface facing the object side, off-axis aberrations, particularly coma aberration, can be favorably corrected.

  Further, since the third lens L3 has a meniscus shape with the convex surface facing the object side, off-axis aberrations, particularly field curvature, are favorably corrected. The third lens L3 has a function of aligning the image position of each image height in the optical axis direction.

In this imaging lens, when the paraxial radius of curvature of the object side surface of the first lens L1 is r1, and the paraxial radius of curvature of the image side surface of the first lens L1 is r2, the following conditional expression ( 1) is satisfied.
−1.2 <r1 / r2 <−0.5 Formula (1)

  In this imaging lens, since the conditional expression (1) is satisfied, the object-side surface and the image-side surface share the positive refractive power of the first lens L1, and thus the refractive power of each surface is large. The axial aberration and the off-axis aberration are well balanced and the aberration can be corrected well, and as a result, the required optical performance can be obtained. It is also preferable to share the positive refractive power of the first lens L1 between the object side surface and the image side surface from the viewpoint of reducing the influence of manufacturing errors. In this way, the refractive power of each surface does not become too large. This is because if the refractive power is too large, the optical performance is likely to be greatly deteriorated when a surface shape error or eccentricity occurs due to a manufacturing error.

For the same reason, in this imaging lens, it is more preferable that the following conditional expression (1-2) (equation (4) in “Claims”) is satisfied.
−1.2 <r1 / r2 <−0.9 Formula (1-2)

  Furthermore, in order to make the aberration correction capability of the first lens L1 more satisfactory, it is preferable that at least one surface, preferably both surfaces, of the first lens L1 is aspherical. Also, it is preferable that at least one surface, preferably both surfaces, of the second lens L2 is an aspherical surface. Furthermore, in order to make the function of aligning the image positions of the respective image heights of the third lens L3 in the optical axis direction more satisfactory, the third lens L3 has at least one surface, preferably both surfaces are aspherical. It is preferable that it is made.

  The third lens L3 preferably has a positive refractive power. Since the third lens L3 has a positive refractive power, the incident angle of the off-axis light beam on the image plane can be reduced, and the exit pupil position can be moved away from the image plane. That is, the exit pupil position far from the image plane required from the characteristics of the solid-state image sensor can be secured, and the characteristics preferable as an imaging lens used in combination with the solid-state image sensor can be obtained.

Further, in order to reduce the incident angle of off-axis rays to the image plane and move the exit pupil position away from the image plane, the focal length of the third lens L3 is f3, and the focal length of the entire imaging lens system is f. When, it is preferable that the following conditional expression (2) is satisfied.
0.5 <f3 / f <6 Formula (2)

In addition, in this imaging lens, the angle of incidence of off-axis rays to the image plane is further reduced to move the exit pupil position away from the image plane, so that the following conditional expression (2-2) is satisfied. preferable.
1 <f3 / f <3 Formula (2-2)

In this imaging lens, it is more preferable that the following conditional expression (3) is satisfied, where f1 is the focal length of the first lens L1 and f is the focal length of the entire imaging lens system. Satisfying conditional expression (3) makes it easier to achieve the required reduction in size and thickness and correction of various aberrations, and as a result, the required optical total length and optical performance can be obtained. .
0 <f1 / f <0.7 Formula (3)

In order to make it easier to reduce the size and thickness and correct various aberrations, and to obtain the required optical total length and optical performance, the following conditional expression (3-2) is further satisfied. More preferred.
0 <f1 / f <0.6 Formula (3-2)

  In this imaging lens, an appropriate optical material such as a synthetic resin material (plastic) or glass can be used as a material forming the first to third lenses L1, L2, and L3. For example, as the optical constants of the materials of these lenses L1, L2, and L3, the refractive index Nd at the d-line (wavelength 587.6 nm) is 1.4 to 2.0, and the Abbe number νd at the d-line is 20 to 85. A range is preferred.

  Further, the materials of these lenses L1, L2, and L3 are those having a refractive index Nd of 1.45 to 1.9 and an Abbe number νd of 20 to 70 from the viewpoint of availability and manufacturing cost. Is more preferable.

  For the first lens L1, for example, by using a low dispersion material having an Abbe number νd of about 50 or more, chromatic aberration, particularly axial chromatic aberration, can be corrected well. Further, chromatic aberration can be corrected more favorably by using a low dispersion glass having an Abbe number νd of 60 or more. Further, by using a high refractive index glass material having a refractive index Nd of about 1.6 to 2.0 for the first lens L1, a necessary refractive power can be obtained without excessively increasing the curvature of each surface. Can do. By using such a high refractive index glass material, if the curvature of each surface of the first lens L1 is not excessively increased, processing of the molding die and molding using this molding die are facilitated. be able to.

  For the second lens L2, for example, chromatic aberration can be favorably corrected by using a high dispersion material having an Abbe number νd of about 30 or less. Further, for the second lens L2, by using a high refractive index glass material having a refractive index Nd of about 1.6 to 2.0, the necessary refractive power is obtained without excessively increasing the curvature of each surface. be able to. By using such a high refractive index glass material, if the curvature of each surface of L2 is not excessively increased, the processing of the molding die and the molding using this molding die can be facilitated.

  For the third lens L3, for example, by using a low dispersion material having an Abbe number νd of about 50 or more, chromatic aberration, particularly lateral chromatic aberration, can be favorably corrected. Further, for the third lens L3, chromatic aberration can be corrected more favorably by using a low dispersion glass having an Abbe number νd of 60 or more.

  Since the third lens L3 has a smaller refractive power than the first and second lenses L1 and L2, the third lens L3 is formed using a plastic material having a low refractive index and low dispersion, for example, a refractive index of about Nd1.53 and an Abbe number of about νd56. May be. As such low refractive index and low dispersion plastic materials, there are many plastic materials with good moldability, that is, plastic materials whose optical performance does not deteriorate due to residual stress during molding, etc., so that good optical performance can be obtained. . Therefore, from the viewpoint of availability and manufacturing cost, it is preferable to use a plastic material as the material forming the third lens L3.

  The first to third lenses L1, L2, and L3 can be molded by a precision mold press. If the first to third lenses L1, L2, and L3 are molded by a precision mold press, when the lenses L1, L2, and L3 are molded, the shift amount between the first surface and the second surface of each lens is 10 μm or less, The inclination of the axis between the first surface and the second surface (molding tilt) can be made within 2 minutes, and an imaging lens having high imaging performance can be configured.

  Hereinafter, the present invention will be specifically described by giving examples according to the present invention. In addition, this invention is not limited to the structure of these Examples.

The symbols used in the following description of each example are as follows.
R: radius of curvature of refracting surface [mm]
D: Distance between top surfaces of refractive surfaces [mm]
Nd: Refractive index of lens material at d-line νd: Abbe number of lens material at d-line f: Focal length of entire lens system [mm]
F: F number 2Y: Image size (Y: Maximum image height) [mm]

The shape of the aspherical surface is represented by the following aspherical expression in an orthogonal coordinate system in which the intersection of the surface and the optical axis is the origin and the optical axis direction is the Z axis.
Z = Ch ² / [1 + √ {1- (1 + K) C 2 h 2} ] _{^{+ A 4 h 4 + A 6}} h 6 + A 8 h 8 + A 10 h 10 + A 12 h 12 + A 14 h 14

However, symbols in this aspherical expression are as follows.
h = √ (X ² + Y ² )
C: Paraxial curvature (C = 1 / R)
K: Conic constant A _{4 to} A ₁₄ : 4th to 14th aspherical coefficients

[Example 1]
FIG. 1 is a cross-sectional view illustrating a configuration of an imaging lens according to Example 1 of the present invention.

  The lens data in Example 1 of the present invention is shown in [Table 1] below.

  [F = 4.082, F = 3, 2Y = 5.0]

In the imaging lens according to the first embodiment, the following relationship is established.
r1 / r2 = −0.981
f3 / f = 1.385 (f3 = 5.654)
f1 / f = 0.558 (f1 = 2.280)
That is, conditional expression (1), conditional expression (1-2), conditional expression (2), conditional expression (2-2), conditional expression (3), and conditional expression (3-2) are satisfied.

  FIG. 2 is an aberration diagram (spherical aberration, meridional coma aberration (solid line is d-line (587.6 nm), dotted line is g-line (435.8 nm))) and astigmatism in Example 1 of the present invention. (The one-dot chain line is sagittal, the two-dot chain line is meridional) and distortion).

  As shown in FIG. 2, the imaging lens in the first embodiment has various aberrations corrected favorably, and is suitable as an imaging lens that constitutes an imaging device in combination with a small imaging element having high resolution.

  FIG. 3 is a graph showing the MTF in the vicinity of the focal position of the imaging lens according to Example 1 of the present invention.

  When this imaging lens confirms the MTF (Modulation Transfer Function) peak value near the focal position and the change characteristics of the MTF in the optical axis direction at a spatial frequency of 150 lp / mm, various aberrations (spherical aberration, coma aberration) Astigmatism, chromatic aberration, etc.) are well corrected, as shown in FIG. 3, the peak value of MTF in the vicinity of the focal position is sufficiently high, and the peak position of MTF for each image height is The optical axis direction agrees well. In FIG. 3, “*” indicates the MTF at an image height of 0 mm with a spatial frequency of 150 lp / mm, “♦” indicates the MTF in the sagittal direction at an image height of 2.5 mm, and “■” indicates the image height 2 The MTF for the meridional direction at .5 mm is shown.

  Therefore, in this imaging lens, it is possible to configure a small imaging device having high resolution in combination with a solid-state imaging device with high pixel density and high density in combination with an exit pupil position far from the image plane. it can.

[Example 2]
FIG. 4 is a cross-sectional view illustrating a configuration of an imaging lens according to Example 2 of the present invention.

  Lens data in Example 2 of the present invention is shown in [Table 2] below.

  [F = 4.082, F = 3, 2Y = 5.0]

In the imaging lens according to the second embodiment, the following relationship is established.
r1 / r2 = −1.062
f3 / f = 1.453 (f3 = 5.931)
f1 / f = 0.535 (f1 = 2.184)
That is, conditional expression (1), conditional expression (1-2), conditional expression (2), conditional expression (2-2), conditional expression (3), and conditional expression (3-2) are satisfied.

  FIG. 5 is an aberration diagram of the imaging lens in Example 2 of the present invention (spherical aberration, meridional coma aberration (solid line is d-line (587.6 nm), dotted line is g-line (435.8 nm)), astigmatism. (The one-dot chain line is sagittal, the two-dot chain line is meridional) and distortion).

  In the imaging lens according to the second embodiment, various aberrations are favorably corrected as shown in FIG. 5, and the imaging lens is suitable as an imaging lens constituting an imaging apparatus in combination with a small imaging element having high resolution.

  FIG. 6 is a graph illustrating the MTF in the vicinity of the focal position of the imaging lens according to the second embodiment of the present invention.

  When this imaging lens confirms the MTF (Modulation Transfer Function) peak value near the focal position and the change characteristics of the MTF in the optical axis direction at a spatial frequency of 150 lp / mm, various aberrations (spherical aberration, coma aberration) Astigmatism, chromatic aberration, etc.) are well corrected, as shown in FIG. 6, the peak value of the MTF near the focal position is sufficiently high, and the peak position of the MTF for each image height is The optical axis direction agrees well. In FIG. 6, “*” indicates the MTF at an image height of 0 mm with a spatial frequency of 150 lp / mm, “♦” indicates the MTF in the sagittal direction at an image height of 2.5 mm, and “■” indicates the image height of 2. The MTF for the meridional direction at .5 mm is shown.

  Therefore, in this imaging lens, it is possible to configure a small imaging device having high resolution in combination with a solid-state imaging device with high pixel density and high density in combination with an exit pupil position far from the image plane. it can.

Example 3
FIG. 7 is a cross-sectional view illustrating a configuration of an imaging lens according to Example 3 of the present invention.

  Lens data in Example 3 of the present invention is shown in [Table 3] below.

  [F = 4.181, F = 3.2, 2Y = 5.0]

In the imaging lens according to Example 3, the following relationship is established.
r1 / r2 = −0.992
f3 / f = 2.874 (f3 = 12.014)
f1 / f = 0.530 (f1 = 2.214)
That is, conditional expression (1), conditional expression (1-2), conditional expression (2), conditional expression (2-2), conditional expression (3), and conditional expression (3-2) are satisfied.

  FIG. 8 is an aberration diagram of the imaging lens in Example 3 of the present invention (spherical aberration, meridional coma aberration (solid line is d-line (587.6 nm), dotted line is g-line (435.8 nm)), astigmatism. (The one-dot chain line is sagittal, the two-dot chain line is meridional) and distortion).

  In the imaging lens according to the third embodiment, as shown in FIG. 8, various aberrations are favorably corrected, and the imaging lens is suitable as an imaging lens constituting an imaging apparatus in combination with a small imaging element having high resolution.

  FIG. 9 is a graph showing MTF in the vicinity of the focal position of the imaging lens according to Example 3 of the present invention.

  When this imaging lens confirms the MTF (Modulation Transfer Function) peak value near the focal position and the change characteristics of the MTF in the optical axis direction at a spatial frequency of 150 lp / mm, various aberrations (spherical aberration, coma aberration) Astigmatism, chromatic aberration, etc.) are well corrected, as shown in FIG. 9, the MTF peak value near the focal position is sufficiently high, and the MTF peak position for each image height is The optical axis direction agrees well. In FIG. 9, “*” represents the MTF at an image height of 0 mm with a spatial frequency of 150 lp / mm, “♦” represents the MTF in the sagittal direction at an image height of 2.5 mm, and “■” represents the image height of 2. The MTF for the meridional direction at .5 mm is shown.

  Therefore, in this imaging lens, it is possible to configure a small imaging device having high resolution in combination with a solid-state imaging device with high pixel density and high density in combination with an exit pupil position far from the image plane. it can.

Example 4
FIG. 10 is a cross-sectional view illustrating a configuration of an imaging lens according to Example 4 of the present invention.

  Lens data in Example 4 of the present invention is shown in [Table 4] below.

  [F = 4.083, F = 3, 2Y = 5.0]

In the imaging lens according to Example 4, the following relationship is established.
r1 / r2 = −0.908
f3 / f = 5.588 (f3 = 22.815)
f1 / f = 0.527 (f1 = 2.153)
That is, conditional expression (1), conditional expression (1-2), conditional expression (2), conditional expression (3), and conditional expression (3-2) are satisfied.

  FIG. 11 is an aberration diagram of the imaging lens in Example 4 of the present invention (spherical aberration, meridional coma aberration (solid line is d-line (587.6 nm), dotted line is g-line (435.8 nm)), astigmatism. (The one-dot chain line is sagittal, the two-dot chain line is meridional) and distortion).

  In the imaging lens in Example 4, as shown in FIG. 11, various aberrations are favorably corrected, and it is suitable as an imaging lens constituting an imaging apparatus in combination with a small imaging element having high resolution.

  FIG. 12 is a graph showing MTF in the vicinity of the focal position of the imaging lens according to Example 4 of the present invention.

  When this imaging lens confirms the MTF (Modulation Transfer Function) peak value near the focal position and the change characteristics of the MTF in the optical axis direction at a spatial frequency of 150 lp / mm, various aberrations (spherical aberration, coma aberration) Astigmatism, chromatic aberration, etc.) are well corrected, as shown in FIG. 12, the peak value of MTF near the focal position is sufficiently high, and the peak position of MTF for each image height is The optical axis direction agrees well. In FIG. 12, “*” indicates the MTF at an image height of 0 mm with a spatial frequency of 150 lp / mm, “♦” indicates the MTF in the sagittal direction at an image height of 2.5 mm, and “■” indicates the image height of 2. The MTF for the meridional direction at .5 mm is shown.

  Therefore, in this imaging lens, it is possible to configure a small imaging device having high resolution in combination with a solid-state imaging device with high pixel density and high density in combination with an exit pupil position far from the image plane. it can.

Example 5
FIG. 13 is a cross-sectional view illustrating a configuration of an imaging lens according to Example 5 of the present invention.

  Lens data in Example 5 of the present invention is shown in [Table 5] below.

  [F = 4.083, F = 3.1, 2Y = 5.0]

In the imaging lens according to the fifth embodiment, the following relationship is established.
r1 / r2 = −0.871
f1 / f = 0.511 (f1 = 2.86)
That is, conditional expression (1), conditional expression (3), and conditional expression (3-2) are satisfied.

  FIG. 14 is an aberration diagram of the image pickup lens in Example 5 of the present invention (spherical aberration, meridional coma aberration (solid line is d-line (587.6 nm), dotted line is g-line (435.8 nm)), astigmatism. (The one-dot chain line is sagittal, the two-dot chain line is meridional) and distortion).

  In the imaging lens according to the fifth embodiment, as shown in FIG. 14, various aberrations are favorably corrected, and the imaging lens is suitable as an imaging lens constituting an imaging apparatus in combination with a small imaging element having a high resolution.

  FIG. 15 is a graph showing MTF in the vicinity of the focal position of the imaging lens according to Example 5 of the present invention.

  When this imaging lens confirms the MTF (Modulation Transfer Function) peak value near the focal position and the change characteristics of the MTF in the optical axis direction at a spatial frequency of 150 lp / mm, various aberrations (spherical aberration, coma aberration) Astigmatism, chromatic aberration, etc.) are well corrected, as shown in FIG. 15, the peak value of MTF near the focal position is sufficiently high, and the peak position of MTF for each image height is The optical axis direction agrees well. In FIG. 15, “*” indicates the MTF at an image height of 0 mm with a spatial frequency of 150 lp / mm, “♦” indicates the MTF in the sagittal direction at an image height of 2.5 mm, and “■” indicates the image height 2 The MTF for the meridional direction at .5 mm is shown.

  Therefore, in this imaging lens, a small-sized imaging device having high resolution can be configured in combination with a solid-state imaging device with high pixels and high density.

Example 6
FIG. 16 is a cross-sectional view illustrating a configuration of an imaging lens according to Example 6 of the present invention.

  Lens data in Example 6 of the present invention are shown in Table 6 below.

  [F = 4.084, F = 3, 2Y = 5.0]

In the imaging lens according to Example 6, the following relationship is established.
r1 / r2 = −0.901
f3 / f = 1.413 (f3 = 5.771)
f1 / f = 0.543 (f1 = 2.217)
That is, conditional expression (1), conditional expression (1-2), conditional expression (2), conditional expression (2-2), conditional expression (3), and conditional expression (3-2) are satisfied.

  FIG. 17 is an aberration diagram of the image pickup lens in Example 6 of the present invention (spherical aberration, meridional coma aberration (solid line is d-line (587.6 nm), dotted line is g-line (435.8 nm)), astigmatism. (The one-dot chain line is sagittal, the two-dot chain line is meridional) and distortion).

  In the imaging lens in Example 6, as shown in FIG. 17, various aberrations are corrected favorably, and it is suitable as an imaging lens constituting an imaging apparatus in combination with a small imaging element having high resolution.

  FIG. 18 is a graph showing MTF in the vicinity of the focal position of the imaging lens according to Example 6 of the present invention.

  When this imaging lens confirms the MTF (Modulation Transfer Function) peak value near the focal position and the change characteristics of the MTF in the optical axis direction at a spatial frequency of 150 lp / mm, various aberrations (spherical aberration, coma aberration) Astigmatism, chromatic aberration, etc.) are well corrected, as shown in FIG. 18, the peak value of MTF near the focal position is sufficiently high, and the peak position of MTF for each image height is The optical axis direction agrees well. In FIG. 18, “*” indicates the MTF at an image height of 0 mm with a spatial frequency of 150 lp / mm, “♦” indicates the MTF in the sagittal direction at an image height of 2.5 mm, and “■” indicates the image height of 2. The MTF for the meridional direction at .5 mm is shown.

  Therefore, in this imaging lens, it is possible to configure a small imaging device having high resolution in combination with a solid-state imaging device with high pixel density and high density in combination with an exit pupil position far from the image plane. it can.

Example 7
FIG. 19 is a cross-sectional view illustrating a configuration of an imaging lens according to Example 7 of the present invention.

  Lens data in Example 7 of the present invention is shown in [Table 7] below.

  [F = 4.083, F = 2.9, 2Y = 5.0]

In the imaging lens according to Example 7, the following relationship is established.
r1 / r2 = −0.921
f3 / f = 1.424 (f3 = 5.815)
f1 / f = 0.554 (f1 = 2.263)
That is, conditional expression (1), conditional expression (1-2), conditional expression (2), conditional expression (2-2), conditional expression (3), and conditional expression (3-2) are satisfied.

  FIG. 20 is an aberration diagram of the image pickup lens in Example 7 of the present invention (spherical aberration, meridional coma aberration (solid line is d-line (587.6 nm), dotted line is g-line (435.8 nm)), astigmatism. (The one-dot chain line is sagittal, the two-dot chain line is meridional) and distortion).

  In the imaging lens in Example 7, various aberrations are favorably corrected as shown in FIG. 20, and the imaging lens is suitable as an imaging lens constituting an imaging apparatus in combination with a small imaging element having high resolution.

  FIG. 21 is a graph showing MTF in the vicinity of the focal position of the imaging lens according to Example 7 of the present invention.

  When this imaging lens confirms the MTF (Modulation Transfer Function) peak value near the focal position and the change characteristics of the MTF in the optical axis direction at a spatial frequency of 150 lp / mm, various aberrations (spherical aberration, coma aberration) Astigmatism, chromatic aberration, etc.) are well corrected, as shown in FIG. 21, the peak value of MTF near the focal position is sufficiently high, and the peak position of MTF for each image height is The optical axis direction agrees well. In FIG. 21, “*” represents the MTF at an image height of 0 mm with a spatial frequency of 150 lp / mm, “♦” represents the MTF in the sagittal direction at an image height of 2.5 mm, and “■” represents the image height of 2. The MTF for the meridional direction at .5 mm is shown.

  Therefore, in this imaging lens, it is possible to configure a small imaging device having high resolution in combination with a solid-state imaging device with high pixel density and high density in combination with an exit pupil position far from the image plane. it can.

Example 8
FIG. 22 is a cross-sectional view illustrating a configuration of an imaging lens according to Example 8 of the present invention.

  Lens data in Example 8 of the present invention are shown in Table 8 below.

  [F = 4.078, F = 3, 2Y = 5.0]

In the imaging lens according to Example 8, the following relationship is established.
r1 / r2 = −0.776
f3 / f = 1.342 (f3 = 5.473)
f1 / f = 0.521 (f1 = 2.123)
That is, conditional expression (1), conditional expression (2), conditional expression (2-2), conditional expression (3), and conditional expression (3-2) are satisfied.

  FIG. 23 is an aberration diagram of the image pickup lens in Example 8 of the present invention (spherical aberration, meridional coma aberration (solid line is d-line (587.6 nm), dotted line is g-line (435.8 nm)), astigmatism. (The one-dot chain line is sagittal, the two-dot chain line is meridional) and distortion).

  In the imaging lens in Example 8, as shown in FIG. 23, various aberrations are satisfactorily corrected, which is suitable as an imaging lens constituting an imaging device in combination with a small imaging element having high resolution.

  FIG. 24 is a graph showing MTF in the vicinity of the focal position of the imaging lens according to Example 8 of the present invention.

  When this imaging lens confirms the MTF (Modulation Transfer Function) peak value near the focal position and the change characteristics of the MTF in the optical axis direction at a spatial frequency of 150 lp / mm, various aberrations (spherical aberration, coma aberration) Astigmatism, chromatic aberration, etc.) are well corrected, as shown in FIG. 24, the peak value of MTF near the focal position is sufficiently high, and the peak position of MTF for each image height is The optical axis direction agrees well. In FIG. 24, “*” represents the MTF at an image height of 0 mm with a spatial frequency of 150 lp / mm, “♦” represents the MTF in the sagittal direction at an image height of 2.5 mm, and “■” represents the image height of 2. The MTF for the meridional direction at .5 mm is shown.

  Therefore, in this imaging lens, it is possible to configure a small imaging device having high resolution in combination with a solid-state imaging device with high pixel density and high density in combination with an exit pupil position far from the image plane. it can.

Example 9
FIG. 25 is a cross-sectional view illustrating a configuration of an imaging lens according to Example 9 of the present invention.

  Lens data in Example 9 of the present invention are shown in Table 9 below.

  [F = 4.078, F = 2.9, 2Y = 5.0]

In the imaging lens according to Example 9, the following relationship is established.
r1 / r2 = −0.677
f3 / f = 1.392 (f3 = 5.676)
f1 / f = 0.552 (f1 = 2.249)
That is, conditional expression (1), conditional expression (2), conditional expression (2-2), conditional expression (3), and conditional expression (3-2) are satisfied.

  FIG. 26 is an aberration diagram of the image pickup lens in Example 9 of the present invention (spherical aberration, meridional coma aberration (solid line is d-line (587.6 nm), dotted line is g-line (435.8 nm)), astigmatism. (The one-dot chain line is sagittal, the two-dot chain line is meridional) and distortion).

  As shown in FIG. 26, in the imaging lens in Example 9, various aberrations are favorably corrected, which is suitable as an imaging lens that constitutes an imaging apparatus in combination with a small imaging element having high resolution.

  FIG. 27 is a graph showing MTF in the vicinity of the focal position of the imaging lens according to Example 9 of the present invention.

  When this imaging lens confirms the MTF (Modulation Transfer Function) peak value near the focal position and the change characteristics of the MTF in the optical axis direction at a spatial frequency of 150 lp / mm, various aberrations (spherical aberration, coma aberration) Astigmatism, chromatic aberration, etc.) are well corrected, as shown in FIG. 27, the peak value of MTF near the focal position is sufficiently high, and the peak position of MTF for each image height is The optical axis direction agrees well. In FIG. 27, “*” indicates the MTF at an image height of 0 mm with a spatial frequency of 150 lp / mm, “♦” indicates the MTF in the sagittal direction at an image height of 2.5 mm, and “■” indicates the image height of 2. The MTF for the meridional direction at .5 mm is shown.

  Therefore, in this imaging lens, it is possible to configure a small imaging device having high resolution in combination with a solid-state imaging device with high pixel density and high density in combination with an exit pupil position far from the image plane. it can.

Example 10
FIG. 28 is a cross-sectional view illustrating a configuration of an imaging lens according to Example 10 of the present invention.

  Lens data in Example 10 of the present invention are shown in Table 10 below.

  [F = 4.078, F = 3, 2Y = 5.0]

In the imaging lens according to Example 10, the following relationship is established.
r1 / r2 = −1.181
f3 / f = 1.122 (f3 = 4.576)
f1 / f = 0.531 (f1 = 2.165)
That is, conditional expression (1), conditional expression (1-2), conditional expression (2), conditional expression (2-2), conditional expression (3), and conditional expression (3-2) are satisfied.

  FIG. 29 is an aberration diagram of the imaging lens in Example 10 of the present invention (spherical aberration, meridional coma aberration (solid line is d-line (587.6 nm), dotted line is g-line (435.8 nm)), astigmatism. (The one-dot chain line is sagittal, the two-dot chain line is meridional) and distortion).

  In the imaging lens in Example 10, as shown in FIG. 29, various aberrations are corrected favorably, and it is suitable as an imaging lens constituting an imaging apparatus in combination with a small imaging element having high resolution.

  FIG. 30 is a graph showing MTF in the vicinity of the focal position of the imaging lens according to Example 10 of the present invention.

  When this imaging lens confirms the MTF (Modulation Transfer Function) peak value near the focal position and the change characteristics of the MTF in the optical axis direction at a spatial frequency of 150 lp / mm, various aberrations (spherical aberration, coma aberration) Astigmatism, chromatic aberration, etc.) are well corrected, as shown in FIG. 30, the peak value of MTF near the focal position is sufficiently high, and the peak position of MTF for each image height is The optical axis direction agrees well. In FIG. 30, “*” indicates the MTF at an image height of 0 mm with a spatial frequency of 150 lp / mm, “♦” indicates the MTF in the sagittal direction at an image height of 2.5 mm, and “■” indicates the image height of 2. The MTF for the meridional direction at .5 mm is shown.

  Therefore, in this imaging lens, it is possible to configure a small imaging device having high resolution in combination with a solid-state imaging device with high pixel density and high density in combination with an exit pupil position far from the image plane. it can.

It is sectional drawing which shows the structure of the imaging lens in Example 1 of this invention. FIG. 6 is an aberration diagram (spherical aberration, meridional coma aberration, astigmatism, and distortion aberration) of the imaging lens according to Example 1 of the present invention. It is a graph which shows MTF in the focus position vicinity of the imaging lens in Example 1 of this invention. It is sectional drawing which shows the structure of the imaging lens in Example 2 of this invention. It is an aberration diagram (spherical aberration, meridional coma aberration, astigmatism and distortion aberration) of the imaging lens in Example 2 of the present invention. It is a graph which shows MTF in the focal position vicinity of the imaging lens in Example 2 of this invention. It is sectional drawing which shows the structure of the imaging lens in Example 3 of this invention. It is an aberration diagram (spherical aberration, meridional coma aberration, astigmatism and distortion aberration) of the imaging lens in Example 3 of the present invention. It is a graph which shows MTF in the focal position vicinity of the imaging lens in Example 3 of this invention. It is sectional drawing which shows the structure of the imaging lens in Example 4 of this invention. FIG. 10 is an aberration diagram (spherical aberration, meridional coma aberration, astigmatism, and distortion aberration) of the imaging lens according to Example 4 of the present invention. It is a graph which shows MTF in the focus position vicinity of the imaging lens in Example 4 of this invention. It is sectional drawing which shows the structure of the imaging lens in Example 5 of this invention. FIG. 10 is an aberration diagram (spherical aberration, meridional coma aberration, astigmatism, and distortion aberration) of the imaging lens according to Example 5 of the present invention. It is a graph which shows MTF in the focus position vicinity of the imaging lens in Example 5 of this invention. It is sectional drawing which shows the structure of the imaging lens in Example 6 of this invention. It is an aberration diagram (spherical aberration, meridional coma aberration, astigmatism, and distortion aberration) of the imaging lens in Example 6 of the present invention. It is a graph which shows MTF in the focus position vicinity of the imaging lens in Example 6 of this invention. It is sectional drawing which shows the structure of the imaging lens in Example 7 of this invention. It is an aberration diagram (spherical aberration, meridional coma aberration, astigmatism and distortion aberration) of the imaging lens in Example 7 of the present invention. It is a graph which shows MTF in the focal position vicinity of the imaging lens in Example 7 of this invention. It is sectional drawing which shows the structure of the imaging lens in Example 8 of this invention. It is an aberration diagram (spherical aberration, meridional coma aberration, astigmatism and distortion aberration) of the imaging lens in Example 8 of the present invention. It is a graph which shows MTF in the focus position vicinity of the imaging lens in Example 8 of this invention. It is sectional drawing which shows the structure of the imaging lens in Example 9 of this invention. It is an aberration diagram (spherical aberration, meridional coma aberration, astigmatism and distortion aberration) of the imaging lens in Example 9 of the present invention. It is a graph which shows MTF in the focal position vicinity of the imaging lens in Example 9 of this invention. It is sectional drawing which shows the structure of the imaging lens in Example 10 of this invention. It is an aberration diagram (spherical aberration, meridional coma aberration, astigmatism and distortion aberration) of the imaging lens in Example 10 of the present invention. It is a graph which shows MTF in the focus position vicinity of the imaging lens in Example 10 of this invention.

Explanation of symbols

1 filter S aperture stop L1 first lens L2 second lens L3 third lens

Claims (7)

In order from the object side to the image side, an aperture stop, a first biconvex lens having positive refractive power, a second meniscus lens having negative refractive power and a concave surface facing the object side, and A third lens having a meniscus shape having a convex surface facing the object side,
When the paraxial curvature radius of the object side surface of the first lens is r1 and the paraxial curvature radius of the image side surface of the first lens is r2, the following conditional expression (1) is satisfied. An imaging lens characterized by.
−1.2 <r1 / r2 <−0.5 Formula (1)   The imaging lens according to claim 1, wherein at least one of the first to third lenses is an aspherical surface.   The imaging lens according to claim 1, wherein the third lens has a positive refractive power. The following conditional expression (2) is satisfied, where f3 is the focal length of the third lens and f is the focal length of the entire imaging lens system. The imaging lens described in 1.
0.5 <f3 / f <6 Formula (2) The following conditional expression (3) is satisfied, where f1 is the focal length of the first lens and f is the focal length of the entire imaging lens system. The imaging lens described in 1.
0 <f1 / f <0.7 Formula (3) The imaging lens according to any one of claims 1 to 5, wherein the following conditional expression (4) is satisfied.
−1.2 <r1 / r2 <−0.9 Formula (4) The imaging lens according to any one of claims 1 to 6,
An imaging device comprising: an imaging device having an imaging surface arranged on an image surface of the imaging lens.

Images