JP2008139853A - Imaging lens having three-lens configuration, camera module, and portable terminal equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact, high-performance imaging lens having a three-lens configuration, which can properly correct aberrations depending on increase in the number of pixels and to provide a camera module on which the imaging lens is mounted, and portable terminal equipment. <P>SOLUTION: In the imaging lens, an aperture diaphragm St, a first lens L1, a second lens L2 and a third lens L3 are disposed in order from an object side. The first lens L1 comprises a positive lens having a convex surface on the object side and the second lens L2 comprises a meniscus lens having a concave surface on the object side. The imaging lens satisfies the following conditional expressions: (1) f/f3<0.95 and (2) BR2<0, wherein BR2 satisfies BR2=A/D4, wherein A represents a distance from a vertex position P1 on a front surface of the second lens and on an optical axis to a position P2 on a rear surface of the second lens through which a light ray passes toward a corner of an image height, provided that a traveling direction of the light ray is taken as appositive direction, and D4 represents a center thickness of the second lens, f represents a focal length of an entire system, f3 represents a focal length of the third lens. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging lens that forms an optical image of a subject on an imaging device such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), and an optical image formed by the imaging lens is converted into an imaging signal. The present invention relates to a mobile terminal device such as a mobile phone with a camera and an information mobile terminal (PDA: Personal Digital Assistance).

In recent years, image sensors such as CCDs and CMOSs have been greatly reduced in size and pixels. For this reason, the imaging device main body and the lens mounted thereon are also required to be small and have high performance. Further, in order to cope with a high-pixel imaging device, telecentricity (telecentricity), that is, the incident angle of the principal ray to the imaging device is almost parallel to the optical axis (the incident angle on the imaging surface is a method of the imaging surface). It is also required to be close to zero with respect to the line. Conventionally, a three-lens lens has been developed as a small imaging lens (see Patent Documents 1 to 9). Patent Documents 1 and 2 and Patent Document 3 (Example 1) describe an imaging lens having a so-called medium diaphragm configuration in which an aperture diaphragm is disposed between a first lens and a second lens. However, in the case of the structure of the middle diaphragm, if the total length of the lens system is to be shortened, the incident angle of the principal ray on the imaging surface becomes large, and the telecentricity is deteriorated. Therefore, it is conceivable to arrange the aperture stop closest to the object side in order to ensure telecentricity. Patent Document 3 (Example 2) and Patent Documents 4 to 9 describe a three-lens imaging lens in which an aperture stop is disposed closest to the object side.
JP 2003-322792 A JP 2005-352317 A Japanese Patent Laid-Open No. 2005-17440 JP 2005-292235 A JP 2005-345919 A Japanese Patent Laid-Open No. 2004-4466 JP 2004-226487 A JP 2004-240063 A JP 2006-47858 A

  However, with the increase in the number of pixels of the image sensor, development of a lens having higher optical performance is desired. In particular, it is desired to develop an imaging lens in which field curvature and chromatic aberration are favorably corrected while downsizing. Further, when the aperture stop is disposed closest to the object side, the manufacturing variation sensitivity (the degree of change in optical performance due to the manufacturing variation) tends to increase, and the mass production aptitude tends to deteriorate. Therefore, there is a demand for the development of an imaging lens in which the aperture stop is disposed closest to the object side to ensure telecentricity and suppress the sensitivity of manufacturing variation.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a small and high-performance three-lens imaging lens in which various aberrations are well corrected in response to an increase in the number of pixels, and an imaging lens thereof. An object of the present invention is to provide a camera module and a portable terminal device that can be mounted to obtain a high-resolution imaging signal.

The three-lens imaging lens according to the first aspect of the present invention includes an aperture stop, a first lens, a second lens, and a third lens in order from the object side. The first lens is a positive lens having a convex surface facing the object side, and the second lens is a meniscus lens having a concave surface facing the object side, which satisfies the following conditional expression.
f / f3 <0.95 (1)
BR2 <0 (2)
However, in BR2, the light ray direction is positive, the distance from the optical axis vertex position P1 of the second lens front surface to the position P2 where the light beam to the image height corner passes on the rear surface of the second lens is A, and the center of the second lens When the thickness is D4, BR2 = A / D4. Further, f is the focal length of the entire system, and f3 is the focal length of the third lens.

In the imaging lens according to the first aspect of the present invention, the configuration of each lens is made appropriate with a small number of lenses, ie, three as a whole, thereby achieving downsizing and high performance. In particular, since the aperture stop is disposed on the object side of the first lens, the overall length is shortened and telecentricity, that is, the incident angle of the principal ray with respect to the imaging surface can be made close to perpendicular (parallel to the optical axis). Optical performance advantageous to the characteristics of the image sensor can be obtained. In particular, when the conditional expression (2) is satisfied, the rear surface of the second lens is positioned closer to the object side than the front optical axis vertex position P1 in the peripheral portion. This makes it possible to reduce the light emission angle, which is advantageous mainly for correction of field curvature and distortion. Further, by satisfying conditional expression (1), the power of the third lens is optimized, which is advantageous mainly for correction of field curvature and chromatic aberration. As a result, high optical performance corresponding to the increase in the number of pixels can be obtained.
In the imaging lens according to the first aspect of the present invention, it is preferable that the following conditions are appropriately satisfied in order to obtain better optical performance or better manufacturing suitability.

0.22 <(D3 + D4) / f <0.43 (3)
However, D3 is a surface interval on the optical axis between the rear surface of the first lens and the front surface of the second lens.

νd2> 40 and −1.2 <f3 / f <0.0 (4)
Where νd2 is the Abbe number of the second lens.

νd2> 40 and 0.0 <f2 / f <2.0 (5)
Here, νd2 is the Abbe number of the second lens, and f2 is the focal length of the second lens.

The three-lens imaging lens according to the second aspect of the present invention includes an aperture stop, a first lens, a second lens, and a third lens in order from the object side. The first lens is a positive lens having a convex surface facing the object side, and the second lens is a lens having a concave surface facing the object side, which satisfies the following conditional expression.
f / f3 <0.95 (1)
D4 / f <0.136 (6)
However, D4 is the center thickness of the second lens, f is the focal length of the entire system, and f3 is the focal length of the third lens.

In the imaging lens according to the second aspect of the present invention, the configuration of each lens is made appropriate with a small number of lenses, ie, three as a whole, thereby achieving downsizing and high performance. In particular, since the aperture stop is disposed on the object side of the first lens, the overall length is shortened and telecentricity, that is, the incident angle of the principal ray with respect to the imaging surface can be made close to perpendicular (parallel to the optical axis). Optical performance advantageous to the characteristics of the image sensor can be obtained. In particular, when the conditional expression (6) is satisfied, the center thickness of the second lens becomes relatively small, the light emission angle is appropriately maintained, and good resolution performance is easily maintained. Further, it is possible to relatively easily reduce the overall length while keeping the manufacturing variation sensitivity small. In addition, material costs can be reduced. Further, by satisfying conditional expression (1), the power of the third lens is optimized, which is advantageous mainly for correction of field curvature and chromatic aberration. As a result, high optical performance corresponding to the increase in the number of pixels can be obtained.
In the imaging lens according to the second aspect of the present invention, in order to obtain better optical performance or better manufacturability, it is preferable to appropriately satisfy the following conditions.

0.22 <(D3 + D4) / f <0.43 (3)
However, D3 is a surface interval on the optical axis between the rear surface of the first lens and the front surface of the second lens.

νd2> 40 and (D4 + D6) / f <0.31 (7)
Where νd2 is the Abbe number of the second lens, and D6 is the center thickness of the third lens.

D6 / f ≦ 0.155 (8)
However, D6 is the center thickness of the third lens.

f3 / f <−0.4 and −5.6 <f2 / f <−3.3 (10)
Here, f2 is the focal length of the second lens.

νd2> 40 and −1.2 <f3 / f <0.0 (4)
Where νd2 is the Abbe number of the second lens.

f3 / f <−1.66 and 0.1 <| f1 / f2 | <0.5 (11)
Here, f1 is the focal length of the first lens, and f2 is the focal length of the second lens.

-0.5 <f1 / f2 <-0.1 (11) ''
Here, f1 is the focal length of the first lens, and f2 is the focal length of the second lens.

An imaging lens having a three-lens configuration according to the third aspect of the present invention includes an aperture stop, a first lens, a second lens, and a third lens in order from the object side. The first lens is a positive lens having a convex surface facing the object side, and the second lens is a lens having a positive refractive power having a concave surface facing the object side, which satisfies the following conditional expression. .
0.22 <(D3 + D4) / f <0.43 (3)
0 <f2 / f <1 (9)
Where f is the focal length of the entire system, f2 is the focal length of the second lens, D3 is the surface distance on the optical axis between the rear surface of the first lens and the front surface of the second lens, and D4 is the center thickness of the second lens. .

  In the imaging lens according to the third aspect of the present invention, the configuration of each lens is made appropriate with a small number of lenses, that is, three as a whole, thereby achieving downsizing and high performance. In particular, since the aperture stop is disposed on the object side of the first lens, the overall length is shortened and telecentricity, that is, the incident angle of the principal ray with respect to the imaging surface can be made close to perpendicular (parallel to the optical axis). Optical performance advantageous to the characteristics of the image sensor can be obtained. In particular, when the conditional expression (3) is satisfied, it is easy to keep the light beam emission angle appropriately while suppressing the total length, which is advantageous for correction of field curvature. Further, by satisfying conditional expression (9), the power of the second lens is optimized, which is advantageous mainly for correction of field curvature and distortion. As a result, high optical performance corresponding to the increase in the number of pixels can be obtained.

In the imaging lens according to the third aspect of the present invention, in order to obtain better optical performance, it is preferable that the following condition is satisfied.
νd2> 40 and −1.2 <f3 / f <0.0 (4)
Where νd2 is the Abbe number of the second lens and f3 is the focal length of the third lens.

The three-lens imaging lens according to the fourth aspect of the present invention includes an aperture stop, a first lens, a second lens, and a third lens in order from the object side. The first lens is a positive lens having a convex surface facing the object side, the second lens is a lens having a negative refractive power with the concave surface facing the object side, and the third lens is a negative refractive power. And satisfies the following conditional expression.
0.22 <(D3 + D4) / f <0.43 (3)
f3 / f <−0.4 and −5.6 <f2 / f <−3.3 (10)
However, f is the focal length of the entire system, f2 is the focal length of the second lens, f3 is the focal length of the third lens, D3 is the surface distance on the optical axis between the rear surface of the first lens and the front surface of the second lens, D4 Is the center thickness of the second lens.

  In the imaging lens according to the fourth aspect of the present invention, the configuration of each lens is made appropriate with a small number of lenses, that is, three as a whole, thereby achieving downsizing and high performance. In particular, since the aperture stop is disposed on the object side of the first lens, the overall length is shortened and telecentricity, that is, the incident angle of the principal ray with respect to the imaging surface can be made close to perpendicular (parallel to the optical axis). Optical performance advantageous to the characteristics of the image sensor can be obtained. In particular, when the conditional expression (3) is satisfied, it is easy to keep the light beam emission angle appropriately while suppressing the total length, which is advantageous for correction of field curvature. Further, by satisfying conditional expression (10), the power balance of the second lens and the third lens is optimized, which is advantageous for correcting various aberrations. As a result, high optical performance corresponding to the increase in the number of pixels can be obtained.

The three-lens imaging lens according to the fifth aspect of the present invention includes an aperture stop, a first lens, a second lens, and a third lens in order from the object side. The first lens is a positive lens having a convex surface facing the object side, the second lens is a lens having a concave surface facing the object side, and the third lens is a lens having negative refractive power, The following conditional expression is satisfied.
0.22 <(D3 + D4) / f <0.43 (3)
f3 / f <−1.66 and 0.1 <| f1 / f2 | <0.5 (11)
Where f is the focal length of the entire system, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, and D3 is the distance between the rear surface of the first lens and the front surface of the second lens. The surface interval on the optical axis, D4, is the center thickness of the second lens.

  In the imaging lens according to the fifth aspect of the present invention, the configuration of each lens is made appropriate with a small number of lenses, that is, three as a whole, thereby achieving downsizing and high performance. In particular, since the aperture stop is disposed on the object side of the first lens, the overall length is shortened and telecentricity, that is, the incident angle of the principal ray with respect to the imaging surface can be made close to perpendicular (parallel to the optical axis). Optical performance advantageous to the characteristics of the image sensor can be obtained. In particular, when the conditional expression (3) is satisfied, it is easy to keep the light beam emission angle appropriately while suppressing the total length, which is advantageous for correction of field curvature. Moreover, satisfying conditional expression (11) optimizes the power balance of the first lens, the second lens, and the third lens, which is advantageous for correcting various aberrations. As a result, high optical performance corresponding to the increase in the number of pixels can be obtained.

An imaging lens having a three-lens configuration according to the sixth aspect of the present invention includes an aperture stop, a first lens, a second lens, and a third lens in order from the object side. The first lens is a positive lens having a convex surface facing the object side, and the second lens is a lens having a concave surface facing the object side, which satisfies the following conditional expression.
−0.85 <f2 / {f3 · (45−νd2)} <− 0.13 (12)
Where νd2 is the Abbe number of the second lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

In the imaging lens according to the sixth aspect of the present invention, the configuration of each lens is made appropriate with a small number of lenses, ie, three as a whole, thereby achieving miniaturization and high performance. In particular, since the aperture stop is disposed on the object side of the first lens, the overall length is shortened and telecentricity, that is, the incident angle of the principal ray with respect to the imaging surface can be made close to perpendicular (parallel to the optical axis). Optical performance advantageous to the characteristics of the image sensor can be obtained. In particular, when the conditional expression (12) is satisfied, the power of the second lens and the third lens and the dispersion of the second lens are appropriately controlled, chromatic aberration is reduced, and it is caused by misalignment during manufacturing. Variations in image plane are reduced, and a lens system with excellent manufacturing suitability can be obtained. As a result, high optical performance corresponding to the increase in the number of pixels can be obtained.
In the imaging lens according to the sixth aspect of the present invention, in order to obtain better optical performance or better manufacturability, it is preferable to appropriately satisfy the following conditions.

BR2 <0 (2)
However, in BR2, the light ray direction is positive, the distance from the optical axis vertex position P1 of the second lens front surface to the position P2 where the light beam to the image height corner passes on the rear surface of the second lens is A, and the center of the second lens When the thickness is D4, BR2 = A / D4.

0.22 <(D3 + D4) / f <0.43 (3)
D6 / f ≦ 0.155 (8)
Where f is the focal length of the entire system, D3 is the surface spacing on the optical axis between the rear surface of the first lens and the front surface of the second lens, D4 is the center thickness of the second lens, and D6 is the center thickness of the third lens. .

D4 / f <0.136 (6)
Here, f is the focal length of the entire system, and D4 is the center thickness of the second lens.

An imaging lens having a three-lens configuration according to a seventh aspect of the present invention includes, in order from the object side, an aperture stop, a first lens having a positive refractive power, a second lens having a positive refractive power, and a negative lens A third lens having refractive power is disposed. The third lens has a concave surface in the vicinity of the optical axis, and a convex surface in the periphery of the image side, and satisfies the following conditional expression.
f / R6 <−0.4 (13)
However, R6 is the paraxial radius of curvature of the object side surface of the third lens, and f is the focal length of the entire system.

  In the imaging lens according to the seventh aspect of the present invention, the configuration of each lens is made appropriate with a small number of lenses, ie, three as a whole, thereby achieving downsizing and high performance. In particular, since the aperture stop is disposed on the object side of the first lens, the overall length is shortened and telecentricity, that is, the incident angle of the principal ray with respect to the imaging surface can be made close to perpendicular (parallel to the optical axis). Optical performance advantageous to the characteristics of the image sensor can be obtained. In particular, since the shape of the third lens arranged closest to the imaging surface is optimized, it is easy to ensure telecentricity while favorably correcting curvature of field and distortion. As a result, high optical performance corresponding to the increase in the number of pixels can be obtained.

In the imaging lens according to the seventh aspect of the present invention, in order to obtain better optical performance, it is preferable that the following condition is satisfied.
-1.2 <f3 / f <0.0 (14)
Here, f3 is the focal length of the third lens.

0.22 <(D3 + D4) / f <0.43 (3)
However, D3 is the surface interval on the optical axis between the rear surface of the first lens and the front surface of the second lens, and D4 is the center thickness of the second lens.

0 <f2 / f <1 (9)
Here, f2 is the focal length of the second lens.

νd2> 40 and −1.2 <f3 / f <0.0 (4)
Where νd2 is the Abbe number of the second lens and f3 is the focal length of the third lens.

An imaging lens having a three-lens configuration according to an eighth aspect of the present invention includes, in order from the object side, an aperture stop, a first lens having a positive refractive power, a second lens having a positive refractive power, and a negative lens A third lens having a refractive power is provided and satisfies the following conditional expression.
D4 / f <0.136 (6)
−0.85 <f2 / {f3 · (45−νd2)} <− 0.13 (12)
-2.5 <f / f3 <0.0 and 0.5 <f2 / f (15)
Here, D4 is the center thickness of the second lens, νd2 is the Abbe number of the second lens, f is the focal length of the entire system, f2 is the focal length of the second lens, and f3 is the focal length of the third lens.

  In the imaging lens according to the eighth aspect of the present invention, the configuration of each lens is made appropriate with a small number of lenses, ie, three as a whole, thereby achieving downsizing and high performance. In particular, since the aperture stop is disposed on the object side of the first lens, the overall length is shortened and telecentricity, that is, the incident angle of the principal ray with respect to the imaging surface can be made close to perpendicular (parallel to the optical axis). Optical performance advantageous to the characteristics of the image sensor can be obtained. In particular, when the conditional expression (6) is satisfied, the center thickness of the second lens becomes relatively small, the light emission angle is appropriately maintained, and good resolution performance is easily maintained. Further, it is possible to relatively easily reduce the overall length while keeping the manufacturing variation sensitivity small. In addition, material costs can be reduced. Further, by satisfying conditional expression (12), the power of the second lens and the third lens and the dispersion of the second lens are appropriately controlled, the chromatic aberration is reduced, and an image generated due to a positional deviation during manufacturing. Surface variations are reduced, and a lens system with excellent manufacturing suitability can be obtained. Furthermore, satisfying conditional expression (15) optimizes the power balance of the second lens and the third lens, which is advantageous for correcting various aberrations. As a result, high optical performance corresponding to the increase in the number of pixels can be obtained.

In the three-lens imaging lens according to each aspect of the present invention, the first lens, the second lens, and the third lens are preferably aspherical lenses. By optimizing the aspheric shape of each lens, it is advantageous mainly for correction of field curvature and distortion, and better optical performance can be obtained.
For example, it is preferable that the image side surface of the first lens has an aspherical shape whose shape changes toward the object side as compared to the vicinity of the optical axis as it goes to the periphery. For example, it is preferable that the aspherical shape has a concave shape or a shape close to a plane in the vicinity of the optical axis, and becomes a convex shape toward the periphery.
Further, it is preferable that the object side surface of the second lens has an aspherical shape whose shape changes toward the object side as compared to the vicinity of the optical axis as it goes to the periphery. For example, it is preferable to have a concave shape in the vicinity of the optical axis and an aspherical shape that becomes a concave shape having a smaller radius of curvature than the vicinity of the optical axis as it goes to the periphery.
In addition, the aspherical shape in which the image-side surface of the third lens changes toward the image side and eventually changes toward the object side as compared to the vicinity of the optical axis as it goes to the periphery. It is preferable that For example, it is preferably an aspherical shape that has a concave shape near the optical axis, a concave shape with a large absolute value of the radius of curvature until the middle, and a convex shape toward the periphery.

A camera module according to the present invention includes a three-lens imaging lens according to the present invention and an imaging element that outputs an electrical signal corresponding to an optical image formed by the imaging lens.
In the camera module according to the present invention, a high-resolution imaging signal is obtained based on a high-resolution optical image obtained by the three-lens imaging lens according to the present invention.

A portable terminal device according to the present invention includes the camera module according to the present invention.
In the portable terminal device according to the present invention, a high-resolution imaging signal is obtained based on the high-resolution optical image obtained by the three-lens imaging lens of the present invention, and the high-resolution imaging signal is obtained based on the imaging signal. An image is obtained.

  According to the three-lens imaging lens according to each aspect of the present invention, the configuration of each lens is optimized with a small number of lenses of three as a whole. A small and high-performance imaging lens system in which is corrected well can be realized. In addition, better optical performance can be obtained by appropriately satisfying preferable conditions. Alternatively, it is possible to obtain manufacturing aptitude excellent in mass productivity.

  In addition, according to the camera module or the portable terminal device of the present invention, since the imaging signal corresponding to the optical image formed by the high-performance three-lens imaging lens of the present invention is output, high resolution is achieved. Imaging signals can be obtained. In particular, according to the mobile terminal device of the present invention, a high-resolution captured image can be obtained based on the imaging signal.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a first configuration example of an imaging lens according to an embodiment of the present invention. This configuration example corresponds to the lens configuration of a first numerical example (FIGS. 15A and 15B) which will be described later. 2 to 13 show second to thirteenth configuration examples. These correspond to the lens configurations of second to thirteenth numerical examples (FIG. 16A, FIG. 16B) to FIG. 27A, and FIG. 27B described later. 1 to 13, the reference symbol Ri is attached so that the surface of the component on the most object side including the aperture stop St is first, and increases sequentially toward the image side (imaging side). The radius of curvature of the i th surface is shown. A symbol Di indicates a surface interval on the optical axis Z1 between the i-th surface and the i + 1-th surface. In each configuration example, the basic configuration is the same.

  The imaging lens according to the present embodiment is used for various imaging devices using an imaging device such as a CCD or CMOS, particularly for relatively small portable terminal devices such as digital still cameras, camera-equipped mobile phones, and PDAs. Is preferred. FIGS. 43A and 43B show a camera-equipped mobile phone as an example of the mobile terminal device. This camera-equipped mobile phone includes an upper housing 2A and a lower housing 2B, both of which are configured to be rotatable in the direction of the arrow in FIG. The lower housing 2B is provided with operation keys 21 and the like. The upper housing 2A is provided with a camera unit 1 (FIG. 43B), a display unit 22 (FIG. 43A), and the like. The display unit 22 includes a display panel such as an LCD (liquid crystal panel) or an EL (Electro-Luminescence) panel. The display part 22 is arrange | positioned at the side used as an inner surface at the time of folding. The display unit 22 can display various menus related to the telephone function and images taken by the camera unit 1. The camera unit 1 is disposed, for example, on the back side of the upper housing 2A. However, the position where the camera unit 1 is provided is not limited to this. The camera unit 1 has a camera module in which the imaging lens according to the present embodiment is incorporated.

  FIG. 44 shows a configuration example of a camera module used in the camera unit 1. This camera module is provided at a position corresponding to the imaging surface of the imaging lens on the support substrate 4 and the support substrate 4 that supports the lens barrel 3 in which the imaging lens according to the present embodiment is accommodated. Image pickup device. The camera module also includes a flexible substrate 5 electrically connected to the imaging device on the support substrate 4 and signal processing on the terminal device body side in the camera-equipped mobile phone or the like while being electrically connected to the flexible substrate 5. And an external connection terminal 6 configured to be connectable to a circuit. These components are integrally configured.

  In this camera module, the optical image formed by the imaging lens is converted into an electrical imaging signal by the imaging device, and the imaging signal is processed by the signal processing on the terminal device body side via the flexible substrate 5 and the external connection terminal 6. Output to the circuit. Here, in this camera module, a high-resolution imaging signal can be obtained by using the imaging lens according to the present embodiment. On the terminal device body side, a high-resolution image can be generated based on the imaging signal.

  As shown in FIGS. 1 to 13, the imaging lens according to the present embodiment includes a first lens L1, a second lens L2, and a third lens L3 in order from the object side along the optical axis Z1. Yes. The optical aperture stop St is preferably arranged on the object side as much as possible to ensure telecentricity. In each configuration example, an aperture stop St is disposed on the front side of the first lens L1 and on the most object side of the lens system. An imaging element such as a CCD is disposed on the imaging surface Simg of the imaging lens. Various optical members are arranged between the third lens L3 and the image sensor in accordance with the configuration on the camera side where the lens is mounted. For example, a flat glass plate GC such as a cover glass for protecting the imaging surface or an infrared cut filter is disposed.

  Each of the first lens L1, the second lens L2, and the third lens L3 is preferably aspheric on both surfaces in order to correct various aberrations while reducing the size with a small number of lenses. In that case, a plastic lens is advantageous for processing an aspheric lens, and therefore, it is preferable to appropriately use a plastic lens.

The first lens L1 has a positive refractive power in the vicinity of the optical axis. The object side surface of the first lens L1 is convex toward the object side in the vicinity of the optical axis. The image side surface of the first lens L1 has first, second, fourth, fifth, sixth, seventh and eighth configuration examples (FIGS. 1, 2, 4, 5, 6, In FIGS. 7 and 8), a concave shape is formed on the image side in the vicinity of the optical axis, and a positive meniscus lens is configured in the vicinity of the optical axis. In the third, tenth, eleventh, twelfth and thirteenth configuration examples (FIGS. 3, 10, 11, 12, and 13), the image-side surface of the first lens L1 has an optical axis. A planar shape is formed on the image side in the vicinity, and a planoconvex lens is formed in the vicinity of the optical axis. In the ninth configuration example (FIG. 9), the image-side surface of the first lens L1 has a convex shape on the image side in the vicinity of the optical axis, and has a biconvex lens configuration in the vicinity of the optical axis. The Abbe number νd1 of the first lens L1 is preferably νd1> 50.
Further, it is preferable that the image side surface of the first lens L1 has an aspherical shape whose shape changes toward the object side as compared to the vicinity of the optical axis as it goes to the periphery. For example, it is preferable that the aspherical shape has a concave shape or a shape close to a plane in the vicinity of the optical axis, and becomes a convex shape toward the periphery.

The second lens L2 has a positive or negative refractive power in the vicinity of the optical axis. The object side surface of the second lens L2 is concave on the object side near the optical axis, the image side surface is convex on the image side near the optical axis, and the concave surface on the object side is near the optical axis. It is a meniscus lens configuration.
When the second lens L2 has an aspherical shape, it is preferable that the object-side surface has an aspherical shape whose shape changes toward the object side as compared with the vicinity of the optical axis, for example. It is preferable to have a concave shape in the vicinity of the optical axis and a shape in which the absolute value of the radius of curvature is smaller (a stronger concave surface) in the vicinity than in the vicinity of the optical axis.

The third lens L3 has a positive or negative refractive power in the vicinity of the optical axis. The object side surface of the third lens L3 is convex or concave toward the object side in the vicinity of the optical axis. The image side surface has a concave shape on the image side in the vicinity of the optical axis. For example, the image-side surface of the third lens L3 has a concave shape on the image side in the vicinity of the optical axis, and has a configuration of a positive meniscus lens in the vicinity of the optical axis.
The Abbe number νd3 of the third lens L3 is preferably νd3> 50.

Here, the third lens L3 is a lens arranged closest to the imaging surface. Therefore, in the third lens L3, the luminous flux is separated at each angle of view as compared with the first lens L1 and the second lens L2. Therefore, by appropriately using an aspherical surface in the third lens L3, it is easy to correct aberrations for each angle of view, and it is easy to correct curvature of field and distortion. In addition, it is easy to ensure telecentricity. For this reason, it is preferable that the shape of the third lens L3 in the vicinity of the optical axis is different from the shape in the peripheral portion. Specifically, the object side surface of the third lens L3 is, for example, a concave shape in the vicinity of the optical axis and approaches a plane on the way to the peripheral portion, or a convex shape in the vicinity of the optical axis, and is on the way to the peripheral portion. Then, a concave shape is preferable.
Further, the aspherical surface in which the image side surface of the third lens L3 changes to the image side partway and finally changes to the object side as compared to the vicinity of the optical axis as it goes to the periphery. The shape is preferred. For example, it is preferably an aspherical shape that has a concave shape near the optical axis, a concave shape with a large absolute value of the radius of curvature until the middle, and a convex shape toward the periphery.

  The imaging lens according to the present embodiment preferably satisfies at least one of the following conditional expressions.

f / f3 <0.95 (1)
More preferably,
f / f3 <0.7 (1) '
It is good to be.

BR2 <0.1 (2-0)
Preferably,
BR2 <0 (2)
It is good to be. More preferably,
BR2 <−0.2 (2-1)
It is good to be. Even more preferably,
BR2 <−0.32 (2-2)
It is good to be.

0.22 <(D3 + D4) / f <0.43 (3)
Preferably,
0.25 <(D3 + D4) / f <0.40 (3) ′
It is good to be.

νd2> 40 and −1.2 <f3 / f <0.0 (4)
In the formula (4), f3 / f is preferably
−1.0 <f3 / f <0.0 (4) ′
It is good to be.

  νd2> 40 and 0.0 <f2 / f <2.0 (5)

  D4 / f <0.136 (6)

  νd2> 40 and (D4 + D6) / f <0.31 (7)

  D6 / f ≦ 0.155 (8)

  0.0 <f2 / f <1.0 (9)

f3 / f <−0.4 and −5.6 <f2 / f <−3.3 (10)
In the formula (10), f2 / f is preferably
−5.6 <f2 / f <−3.7 (10) ′
It is good to be.

  f3 / f <−0.4 and 0.5 <f2 / f (10A)

f3 / f <−1.66 and 0.1 <| f1 / f2 | <0.5 (11)
In the formula (11), f1 / f2 is preferably
0.1 <f1 / f2 <0.5 (11) ′
Or
-0.5 <f1 / f2 <-0.1 (11) ''
It is good to be.

  −0.85 <f2 / {f3 · (45−νd2)} <− 0.13 (12)

  f / R6 <−0.4 (13)

  -1.2 <f3 / f <0.0 (14)

  -2.5 <f / f3 <0.0 and 0.5 <f2 / f (15)

In the above conditional expression,
f: focal length of the entire system f1: focal length of the first lens L1 f2: focal length of the second lens L2 f3: focal length of the third lens L3 D3: on the optical axis between the rear surface of the first lens and the front surface of the second lens D4: Center thickness of the second lens L2 D6: Center thickness of the third lens L3 R6: Paraxial radius of curvature of the object side surface of the third lens L3 νd2: Abbe number of the second lens L2.

  In conditional expressions (2-0), (2), (2-1), and (2-2), BR2 is an image height corner from the optical axis vertex position P1 of the second lens front surface to the rear surface of the second lens. BR2 = A / D4, where A is the distance to the position P2 through which the light beam passes and D4 is the center thickness of the second lens L2. The traveling direction of the light beam (the direction from the object side to the image side) is positive. FIGS. 14A and 14B show the concept of this BR2. D4 is larger than 0 because it is the center thickness of the second lens L2. Therefore, if A> 0, BR2> 0. As shown in FIG. 14A, A> 0 is when the traveling direction of the light beam is positive, the rear surface of the second lens is the peripheral portion, and is closer to the image side than the optical axis vertex position P1 of the front surface. Means to be located. If A <0, BR2 <0. As shown in FIG. 14B, A <0 is that when the traveling direction of the light beam is positive, the rear surface of the second lens is the peripheral portion and is closer to the object side than the optical axis vertex position P1 of the front surface. Will be located.

Here, in the present embodiment, a preferred configuration example considering each conditional expression will be described. For example, roughly eight preferred configurations are conceivable. FIG. 29 shows the relationship between these configuration groups and conditional expressions, and the corresponding relationship with examples described later.
<First configuration group>

(Basic configuration 1-1)
In order from the object side, an aperture stop St, a first lens L1, a second lens L2, and a third lens L3 are disposed, and the first lens L1 is a positive lens having a convex surface facing the object side, The second lens L2 is a meniscus lens having a concave surface directed toward the object side, and satisfies the conditional expressions (1) and (2).

Based on the basic configuration 1-1, the following preferable configuration may be used.
(Configuration 1-2)
A configuration that satisfies the basic configuration 1-1 and further satisfies the conditional expression (3).
(Configuration 1-3)
A configuration that satisfies the basic configuration 1-1 or the configuration 1-2 and further satisfies the conditional expression (4).
(Configuration 1-4)
A configuration that satisfies the basic configuration 1-1 and further satisfies the conditional expression (5).

Furthermore, in the configurations 1-1 to 1-4, the configuration satisfying the conditional expression (2-1) or the conditional expression (2-2) may be employed.
<Second component group>

(Basic configuration 2-1)
In order from the object side, an aperture stop St, a first lens L1, a second lens L2, and a third lens L3 are disposed, and the first lens L1 is a positive lens having a convex surface facing the object side, The second lens L2 is composed of a lens having a concave surface directed toward the object side, and satisfies the conditional expressions (1) and (6).

The following preferable configuration may be used based on the basic configuration 2-1.
(Configuration 2-2)
A configuration that satisfies the basic configuration 2-1 and further satisfies the conditional expression (3).
(Configuration 2-3)
A configuration that satisfies the configuration 2-2 and further satisfies the conditional expression (7).
(Configuration 2-4)
A configuration that satisfies the configuration 2-2 or the configuration 2-2 and further satisfies the conditional expression (8).

Moreover, the following preferable structure may be sufficient.
(Configuration 2-5)
A configuration that satisfies the basic configuration 2-1 and further satisfies the conditional expression (10).
(Configuration 2-6)
A configuration that satisfies the basic configuration 2-1 and further satisfies the conditional expression (4).
(Configuration 2-7)
A configuration that satisfies the basic configuration 2-1 and further satisfies the conditional expression (11).
(Configuration 2-8)
A configuration that satisfies the basic configuration 2-1 and further satisfies the conditional expression (11) ″.

Furthermore, in the configurations 2-1 to 2-4, the configuration satisfying the conditional expression (4) and the conditional expression (5) may be employed. Alternatively, in configurations 2-1 to 2-4, a configuration that satisfies conditional expression (3) ′, conditional expression (4) ′, or conditional expression (9) may be used.
<Third component group>

(Basic configuration 3-1)
In order from the object side, an aperture stop St, a first lens L1, a second lens L2, and a third lens L3 are disposed, and the first lens L1 is a positive lens having a convex surface facing the object side, The second lens L2 is composed of a lens having a positive refractive power with the concave surface facing the object side, and satisfies the conditional expressions (3) and (9).

The following preferable configuration may be used based on the basic configuration 3-1.
(Configuration 3-2)
A configuration that satisfies the basic configuration 3-1 and further satisfies the conditional expression (4).

Further, in the configurations 3-1 and 3-2, the configuration satisfying the conditional expression (3) ′ or the conditional expression (4) ′ may be adopted.
<4th group>

(Basic configuration 4-1)
In order from the object side, an aperture stop St, a first lens L1, a second lens L2, and a third lens L3 are disposed, and the first lens L1 is a positive lens having a convex surface facing the object side, The second lens L2 is composed of a lens having negative refractive power with the concave surface facing the object side, and the third lens L3 is composed of a lens having negative refractive power, satisfying conditional expressions (3) and (10). Configuration to do.
<Fifth component group>

(Basic configuration 5-1)
In order from the object side, an aperture stop St, a first lens L1, a second lens L2, and a third lens L3 are disposed, and the first lens L1 is a positive lens having a convex surface facing the object side, The second lens L2 is composed of a lens having a concave surface directed toward the object side, and the third lens L3 is composed of a lens having negative refractive power, and satisfies the conditional expressions (3) and (11).

Furthermore, a configuration that satisfies the conditional expression (11) ′ or the conditional expression (11) ″ based on the basic configuration 5-1 may be used.
<Sixth component group>

(Basic configuration 6-1)
In order from the object side, an aperture stop St, a first lens L1, a second lens L2, and a third lens L3 are disposed, and the first lens L1 is a positive lens having a convex surface facing the object side, A configuration in which the second lens L2 is composed of a lens having a concave surface directed toward the object side and satisfies the conditional expression (12).

The following preferable configuration may be used based on the basic configuration 6-1.
(Configuration 6-2)
A configuration that satisfies the basic configuration 6-1 and further satisfies the conditional expression (2).
(Configuration 6-3)
A configuration that satisfies the configuration 6-1 and further satisfies the conditional expressions (3) and (8).
(Configuration 6-4)
A configuration that satisfies the configuration 6-1 and further satisfies the conditional expression (6).

Furthermore, in the configurations 6-1 to 6-4, the configuration satisfying the conditional expression (2-1) or the conditional expression (2-2) may be employed.
<Seventh group>

(Basic configuration 7-1)
In order from the object side, an aperture stop St, a first lens L1 having a positive refractive power, a second lens L2 having a positive refractive power, and a third lens L3 having a negative refractive power are disposed. The third lens L3 has a configuration in which the object side surface has a concave shape in the vicinity of the optical axis and the image side surface has a convex shape in the peripheral portion, and satisfies the conditional expression (13).

The following preferable configuration may be used based on the basic configuration 7-1.
(Configuration 7-2)
A configuration that satisfies the basic configuration 7-1 and further satisfies the conditional expression (14).

Moreover, the following preferable structure may be sufficient.
(Configuration 7-3)
A configuration that satisfies the basic configuration 7-1 and further satisfies the conditional expression (3).
(Configuration 7-4)
A configuration that satisfies the basic configuration 7-1 and further satisfies the conditional expression (9).
(Configuration 7-5)
A configuration that satisfies the basic configuration 7-4 and further satisfies the conditional expression (4).
<Eighth configuration group>

(Basic configuration 8-1)
In order from the object side, an aperture stop St, a first lens L1 having a positive refractive power, a second lens L2 having a positive refractive power, and a third lens L3 having a negative refractive power are disposed. A configuration that satisfies conditional expressions (6), (12), and (15).

Next, operations and effects of the imaging lens configured as described above will be described.
In this imaging lens, the overall configuration of each lens is optimized by combining appropriate conditions with respect to the lens shape and power distribution, etc., with a small lens configuration of 3 lenses as a whole. It is done.

Further, in this imaging lens, by arranging the aperture stop St on the front side of the first lens L1, it is possible to obtain a lens system that is advantageous for shortening the overall length and ensuring telecentricity. Further, in this imaging lens, it is possible to correct aberrations more effectively by optimizing the aspherical surface of each surface. Telecentricity, that is, the incident angle of the chief ray on the image sensor is almost parallel to the optical axis (the incident angle on the image plane is zero with respect to the normal of the image plane) It is required to be close to In this imaging lens, for example, the image-side surface of the third lens L3, which is the final lens surface closest to the imaging element, has a concave shape on the image side in the vicinity of the optical axis and a convex shape on the image side in the peripheral portion. Thus, aberration correction for each angle of view is appropriately performed, and the incident angle of the light beam to the image sensor is controlled to be equal to or smaller than a certain angle. As a result, unevenness in the amount of light in the entire image plane can be reduced, and it is advantageous for correcting curvature of field and distortion.
The actions and effects of each conditional expression are as follows.

  Conditional expression (1) defines an appropriate power of the third lens L3. By satisfying conditional expression (1), the power of the third lens L3 is optimized, which is advantageous mainly for correction of field curvature and chromatic aberration.

  Conditional expressions (2-0), (2), (2-1), and (2-2) relate to the shape of the second lens. When the value of BR2 is close to 0, the condition of the second lens L2 The position P2 of the rear peripheral portion is close to the front optical axis vertex position P1. When BR2 is positive, as shown in FIG. 14A, when the position P2 of the rear surface peripheral portion of the second lens L2 is located on the image side with respect to the optical axis vertex position P1 of the front surface, and BR2 is negative As shown in FIG. 14B, the position P2 of the rear peripheral portion of the second lens L2 is located on the object side of the front optical axis vertex position P1. As BR2 becomes closer to 0 and the negative value becomes larger, the light emission angle can be made dull, which is advantageous mainly for correction of field curvature and distortion.

  Conditional expression (3) defines an appropriate relationship between the distance between the first lens L1 and the second lens L2 and the center thickness of the second lens L2. Satisfying the conditional expression (3) makes it easy to keep the light emission angle appropriately while suppressing the total length, and is advantageous for correcting curvature of field. If the upper limit of conditional expression (3) is exceeded, the total length becomes large, and it is disadvantageous for correcting curvature of field. If the lower limit is exceeded, the light emission angle cannot be maintained properly. More preferably, by setting the numerical value range to the range of conditional expression (3) ′, better optical performance can be obtained.

  Conditional expression (4) defines an appropriate power of the third lens L3 when the Abbe number of the second lens L2 is νd2> 40. In the conditional expression (4), if f3 / f exceeds the upper limit, it is disadvantageous mainly for correction of axial aberration and astigmatic difference. Exceeding the lower limit is disadvantageous mainly for correcting curvature of field, distortion, and lateral chromatic aberration. More preferably, by setting the numerical value range of f3 / f to the range of conditional expression (4) ′, better optical performance can be obtained.

  Conditional expression (5) defines an appropriate power of the second lens L2 when the Abbe number of the second lens L2 is νd2> 40. By satisfying conditional expression (5), the chromatic aberration of magnification generated in the second lens L2, and further, the field curvature and distortion can be kept good. If f2 / f exceeds the upper limit or lower limit of conditional expression (5), it is disadvantageous mainly for correction of field curvature and distortion.

  Conditional expression (6) defines an appropriate center thickness of the second lens L2. When the conditional expression (6) is satisfied, the center thickness of the second lens L2 becomes relatively small, the light emission angle is appropriately maintained, and good resolution performance is easily maintained. Further, it is possible to relatively easily reduce the overall length while keeping the manufacturing variation sensitivity small.

  Conditional expression (7) defines appropriate center thicknesses of the second lens L2 and the third lens L3 when the Abbe number of the second lens L2 is νd2> 40. Satisfying the conditional expression (7) is advantageous for shortening the overall length while appropriately maintaining the resolution performance and the light emission angle, and suppressing the manufacturing variation sensitivity.

  Conditional expression (8) defines an appropriate center thickness of the third lens L3. By reducing the center thickness of the third lens L3 so as to satisfy the conditional expression (8), it is advantageous for shortening the overall length while keeping the resolution performance and the light emission angle appropriately, and suppressing the manufacturing variation sensitivity. It becomes. When the conditional expression (8) is satisfied, the total length can be reduced relatively easily. Furthermore, material costs can be reduced.

  Conditional expression (9) defines an appropriate power of the second lens L2. Satisfying conditional expression (9) optimizes the power of the second lens L2, which is advantageous mainly for correction of field curvature and distortion. Exceeding the upper and lower limits is disadvantageous mainly for correcting curvature of field and distortion.

Conditional expression (10) defines appropriate powers of the second lens L2 and the third lens L3. By satisfying conditional expression (10), the power balance of the second lens L2 and the third lens L3 is optimized, which is advantageous in correcting various aberrations.
In the state of f3 / f <−0.4, the negative power of the third lens L3 is weak, and the balance of axial aberration, astigmatism, field curvature, and distortion is more balanced than when the negative power is strong. Not enough. Under the condition where the negative power of the third lens L3 is weak, the balance of various aberrations can be maintained well by setting the negative power of the second lens L2 within the range of the conditional expression (10). In the conditional expression (10), when the negative power range of the second lens L2 exceeds the upper limit and the lower limit, the balance of various aberrations cannot be maintained. More preferably, by setting the numerical range to the range of conditional expression (10) ′, better optical performance can be obtained.

  Conditional expression (10) is a preferable condition when the second lens L2 has negative power. However, when conditional expression (10) has positive power, conditional expression (10A) ), Satisfactory optical performance can be obtained.

Conditional expression (11) defines an appropriate power of each lens. By satisfying conditional expression (11), the power balance of the first lens L1, the second lens L2, and the third lens L3 is optimized, which is advantageous for correcting various aberrations.
In the state of f3 / f <−1.66, the negative power of the third lens L3 is weak, and the balance of axial aberration, astigmatism, field curvature, and distortion is more balanced than when the negative power is strong. Not enough. By appropriately defining the value of | f1 / f2 | under the condition that the negative power of the third lens L3 is weak, the balance of various aberrations can be kept good.
If the upper limit of 0.1 <| f1 / f2 | <0.5 is exceeded, the power of the second lens L2 becomes too strong compared to the positive power of the first lens L1, and spherical aberration, field curvature, and coma It becomes difficult to correct aberration and chromatic aberration at the same time. If the lower limit is exceeded, it becomes difficult to correct curvature of field and coma, and good optical performance cannot be obtained. More preferably, by setting the numerical range to the range of conditional expression (11) ′ or (11) ″, better optical performance can be obtained.

  Conditional expression (12) defines an appropriate balance between the power (1 / f2) of the second lens L2 and the power (1 / f3) of the third lens L3 and the dispersion of the second lens L2. This contributes to reducing the overall chromatic aberration. If the upper limit and lower limit of conditional expression (12) are deviated, the balance between axial and lateral chromatic aberration will be lost, and axial and lateral chromatic aberration cannot be kept good at the same time. In order to reduce the overall chromatic aberration, the power balance between the second lens L2 and the third lens L3 is important. At this time, when a material having a small Abbe number is used for the second lens L2, the power of the second lens L2 is weak. Conversely, when the Abbe number νd2 of the second lens L2 is large, it is preferable that the power of the second lens L2 becomes strong. By satisfying conditional expression (12), the power of the second lens L2 and the power of the third lens L3 are appropriately controlled with the value of the Abbe number νd2 being 45 as a boundary.

  Conditional expression (13) defines an appropriate shape of the object side surface of the third lens L3. In order to satisfy the conditional expression (13), the concave shape of the object side surface of the third lens L3 is made relatively strong, so that the emission angle of the light beam is appropriately maintained while maintaining the curvature of field and distortion well. To maintain telecentricity.

  Conditional expression (14) defines an appropriate power of the third lens L3. In conditional expression (14), if f3 / f exceeds the upper limit, it is disadvantageous mainly for correction of axial aberration and astigmatic difference. Exceeding the lower limit is disadvantageous mainly for correcting curvature of field, distortion, and lateral chromatic aberration.

  Conditional expression (15) defines appropriate powers of the second lens L2 and the third lens L3. By satisfying conditional expression (15), the power balance of the second lens L2 and the third lens L3 is optimized, which is advantageous for correcting various aberrations.

  As described above, according to the imaging lens according to the present embodiment, the configuration of each lens is optimized with a small number of lenses of three as a whole. A compact and high-performance imaging lens system in which aberrations are well corrected can be realized. In addition, better optical performance can be obtained by appropriately satisfying preferable conditions. Alternatively, it is possible to obtain manufacturing aptitude excellent in mass productivity. In addition, according to the camera module or the mobile terminal device according to the present embodiment, the electric signal corresponding to the optical image formed by the high-performance imaging lens according to the present embodiment is output. An image pickup signal of an image can be obtained. In particular, according to the mobile terminal device according to the present embodiment, a high-resolution captured image can be obtained based on the imaging signal.

  Next, specific numerical examples of the imaging lens according to the present embodiment will be described. Hereinafter, the first to thirteenth numerical examples will be described together.

  Specific lens data corresponding to the configuration of the imaging lens shown in FIG. 1 is shown as Example 1 in FIGS. 15A and 15B. In particular, FIG. 15A shows the basic lens data, and FIG. 15B shows data on the aspherical surface. In the field of the surface number Si in the lens data shown in FIG. 15A, the surface of the component closest to the object side including the aperture stop St is the first, and the number is sequentially increased toward the image side. The number of the i-th surface (i = 1 to 9) marked with is shown. In the column of the curvature radius Ri, the value (mm) of the curvature radius of the i-th surface from the object side is shown in correspondence with the reference symbol Ri in FIG. Similarly, the column of the surface interval Di indicates the interval (mm) on the optical axis between the i-th surface Si and the i + 1-th surface Si + 1 from the object side. Ndj represents the value of the refractive index for the d-line (wavelength 587.6 nm) of the j-th (j = 1 to 4) optical element from the object side. The column of νdj shows the Abbe number value for the d-line of the j-th optical element from the object side.

In the imaging lens according to Example 1, both surfaces of the first lens L1, the second lens L2, and the third lens L3 are all aspherical. In the basic lens data in FIG. 15A, numerical values of the curvature radii near the optical axis are shown as the curvature radii of these aspheric surfaces. In the numerical values shown as aspherical data in FIG. 15B, the symbol “E” indicates that the subsequent numerical value is a “power exponent” with 10 as the base, and an exponent function with 10 as the base. The numerical value represented by “E” is multiplied by the numerical value before “E”. For example, “1.0E-02” indicates “1.0 × 10 ⁻² ”.

As the aspheric surface data, the values of the coefficients B _n and KA in the aspheric surface expression represented by the following expression (A) are described. More specifically, Z is the length of a perpendicular line (mm) drawn from a point on the aspheric surface at a height Y from the optical axis Z1 to the tangential plane (plane perpendicular to the optical axis Z1) of the apex of the aspheric surface. ). In the imaging lens according to Example 1, the fourth, sixth, eighth, and tenth order coefficients B ₄ , B ₆ , B ₈ , and B ₁₀ are effective as each aspheric surface as the aspheric coefficient B _n. It is expressed using.
Z = C · Y ² / {1+ (1−KA · C ² · Y ² ) ^1/2 } + ΣB _n · Y ⁿ (A)
(N = an integer greater than 3)
However,
Z: Depth of aspheric surface (mm)
Y: Distance from the optical axis to the lens surface (height) (mm)
KA: Conic constant C: Paraxial curvature = 1 / R
(R: paraxial radius of curvature)
B _n : nth-order aspheric coefficient

In the same manner as the imaging lens according to the first embodiment, specific lens data corresponding to the configuration of the imaging lens shown in FIGS. (B) to FIGS. 27 (A) and 27 (B). In any of Examples 2 to 13, as in Example 1, both surfaces of the first lens L1, the second lens L2, and the third lens L3 are all aspherical. In the imaging lens according to Example 9, as in Example 1, each aspheric surface has even-order fourth, sixth, eighth, and tenth coefficients B ₄ , B ₆ , B as the aspheric coefficient B _n. It is represented by effectively using the _8, B _10. Of Examples 2-13, in the embodiment, except for Example 9, a third-order to tenth-order even-order and odd-order coefficients B ₃ .about.B ₁₀ effectively as the aspheric surface is aspherical coefficients B _n It is expressed using.

  In FIG. 28, the values regarding the above-described conditional expressions are collectively shown for the respective examples. In addition, EX. Indicates an embodiment. In FIG. 28, the part highlighted by shading indicates that the value of the example is within the numerical range of the conditional expression.

  FIG. 29 shows the relationship between the above-described configuration groups and conditional expressions, and the corresponding relationship with the above-described embodiments.

  30A to 30C show spherical aberration, astigmatism, and distortion (distortion aberration) in the imaging lens according to Example 1, respectively. Each aberration diagram shows an aberration with the e-line as a reference wavelength. The spherical aberration diagram and the astigmatism diagram also show aberrations for the F line (wavelength 486.13 nm) and the C line (wavelength 656.27 nm). In the astigmatism diagram, the solid line indicates the sagittal direction (S), and the broken line indicates the tangential direction (T). FNo. Indicates the F value, and Y indicates the image height.

  Similarly, various aberrations of the imaging lenses according to Examples 2 to 13 are shown in FIGS. 31A, 31B, 31C to 42A, 42B, and 42. Shown in (C).

  As can be seen from the above numerical data and aberration diagrams, each embodiment is optimized with a small number of lenses, ie, three as a whole, and a compact size in which field curvature, coma aberration, etc. are well corrected. A high-performance imaging lens system can be realized.

  In addition, this invention is not limited to the said embodiment and each Example, A various deformation | transformation implementation is possible. For example, the radius of curvature, the surface interval, and the refractive index of each lens component are not limited to the values shown in the above numerical examples, and may take other values.

It is a lens sectional view corresponding to the imaging lens concerning Example 1 of the present invention. It is lens sectional drawing corresponding to the imaging lens which concerns on Example 2 of this invention. It is lens sectional drawing corresponding to the imaging lens which concerns on Example 3 of this invention. It is lens sectional drawing corresponding to the imaging lens which concerns on Example 4 of this invention. It is a lens sectional view corresponding to the image pick-up lens concerning Example 5 of the present invention. It is lens sectional drawing corresponding to the imaging lens which concerns on Example 6 of this invention. It is lens sectional drawing corresponding to the imaging lens which concerns on Example 7 of this invention. It is lens sectional drawing corresponding to the imaging lens which concerns on Example 8 of this invention. It is lens sectional drawing corresponding to the imaging lens which concerns on Example 9 of this invention. It is lens sectional drawing corresponding to the imaging lens which concerns on Example 10 of this invention. It is lens sectional drawing corresponding to the imaging lens which concerns on Example 11 of this invention. It is a lens sectional view corresponding to the image pick-up lens concerning Example 12 of the present invention. It is lens sectional drawing corresponding to the imaging lens which concerns on Example 13 of this invention. It is explanatory drawing regarding a conditional expression. 2A and 2B are diagrams illustrating lens data of an imaging lens according to Example 1 of the present invention, where FIG. 1A illustrates basic lens data, and FIG. It is a figure which shows the lens data of the imaging lens which concerns on Example 2 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 3 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 4 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 5 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 6 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 7 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 8 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 9 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 10 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 11 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 12 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is a figure which shows the lens data of the imaging lens which concerns on Example 13 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is the figure which showed collectively about the correspondence of each structure group and each Example. It is the figure which showed collectively about the correspondence of a conditional expression and a claim. FIG. 4 is an aberration diagram showing various aberrations of the imaging lens according to Example 1 of the present invention, in which (A) shows spherical aberration, (B) shows astigmatism, and (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 2 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 3 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 4 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 5 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 6 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 7 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 8 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 9 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 10 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 11 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 12 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is an aberration diagram which shows the various aberrations of the imaging lens which concerns on Example 13 of this invention, (A) shows spherical aberration, (B) shows astigmatism, (C) shows distortion. It is a perspective view which shows one structural example of the portable terminal device which concerns on one embodiment of this invention. It is a perspective view which shows one structural example of the camera module which concerns on one embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Camera part, 4 ... Support substrate, 5 ... Flexible substrate, 6 ... External connection terminal, L1 ... 1st lens, L2 ... 2nd lens, L3 ... 3rd lens, GC ... Glass plate, St ... Aperture stop, Ri The radius of curvature of the i-th lens surface from the object side, Di: the surface interval between the i-th and i + 1-th lens surfaces from the object side, Z1, the optical axis.

Claims (28)

In order from the object side, an aperture stop, a first lens, a second lens, and a third lens are disposed,
The first lens is a positive lens having a convex surface facing the object side,
The second lens is a meniscus lens having a concave surface facing the object side,
An imaging lens having a three-lens structure characterized by satisfying the following conditional expression.
f / f3 <0.95 (1)
BR2 <0 (2)
However,
BR2: The light ray direction is positive, the distance from the optical axis apex position P1 on the front surface of the second lens to the position P2 where the light beam to the image height corner passes on the rear surface of the second lens is A, and the center thickness of the second lens is D4 BR2 = A / D4
f: Focal length of the entire system f3: The focal length of the third lens. Furthermore, the following conditional expression is satisfied. The imaging lens with three lenses according to claim 1 characterized by things.
0.22 <(D3 + D4) / f <0.43 (3)
However,
D3: Surface distance on the optical axis between the rear surface of the first lens and the front surface of the second lens. D4: The center thickness of the second lens. Furthermore, the following conditional expression is satisfied. The imaging lens with three lenses according to claim 1 or 2 characterized by things.
νd2> 40 and −1.2 <f3 / f <0.0 (4)
However,
νd2: The Abbe number of the second lens. Furthermore, the following conditional expression is satisfied. The imaging lens with three lenses according to claim 1 characterized by things.
νd2> 40 and 0.0 <f2 / f <2.0 (5)
However,
νd2: Abbe number of the second lens f2: The focal length of the second lens. In order from the object side, an aperture stop, a first lens, a second lens, and a third lens are disposed,
The first lens is a positive lens having a convex surface facing the object side,
The second lens is a lens having a concave surface facing the object side,
An imaging lens having a three-lens structure characterized by satisfying the following conditional expression.
f / f3 <0.95 (1)
D4 / f <0.136 (6)
However,
D4: center thickness of the second lens f: focal length of the entire system f3: focal length of the third lens The three-element imaging lens according to claim 5, further satisfying the following conditional expression.
0.22 <(D3 + D4) / f <0.43 (3)
However,
D3: A surface interval on the optical axis between the rear surface of the first lens and the front surface of the second lens. The three-element imaging lens according to claim 6, further satisfying the following conditional expression.
νd2> 40 and (D4 + D6) / f <0.31 (7)
However,
νd2: Abbe number of the second lens D6: Center thickness of the third lens. 8. The three-lens imaging lens according to claim 6 or 7, wherein the following conditional expression is satisfied.
D6 / f ≦ 0.155 (8)
However,
D6: The center thickness of the third lens. The three-element imaging lens according to claim 5, further satisfying the following conditional expression.
f3 / f <−0.4 and −5.6 <f2 / f <−3.3 (10)
However,
f2: The focal length of the second lens. The three-element imaging lens according to claim 5, further satisfying the following conditional expression.
νd2> 40 and −1.2 <f3 / f <0.0 (4)
However,
νd2: The Abbe number of the second lens. The three-element imaging lens according to claim 5, further satisfying the following conditional expression.
f3 / f <−1.66 and 0.1 <| f1 / f2 | <0.5 (11)
However,
f1: The focal length of the first lens f2: The focal length of the second lens. The three-element imaging lens according to claim 5, further satisfying the following conditional expression.
-0.5 <f1 / f2 <-0.1 (11) ''
However,
f1: The focal length of the first lens f2: The focal length of the second lens. In order from the object side, an aperture stop, a first lens, a second lens, and a third lens are disposed,
The first lens is a positive lens having a convex surface facing the object side,
The second lens is a lens having a positive refractive power with a concave surface facing the object side,
An imaging lens having a three-lens structure characterized by satisfying the following conditional expression.
0.22 <(D3 + D4) / f <0.43 (3)
0 <f2 / f <1 (9)
However,
f: Focal length of the entire system f2: Focal length of the second lens D3: Surface distance on the optical axis between the rear surface of the first lens and the front surface of the second lens D4: The center thickness of the second lens. The three-element imaging lens according to claim 13, further satisfying the following conditional expression:
νd2> 40 and −1.2 <f3 / f <0.0 (4)
However,
νd2: Abbe number of the second lens f3: The focal length of the third lens. In order from the object side, an aperture stop, a first lens, a second lens, and a third lens are disposed,
The first lens is a positive lens having a convex surface facing the object side,
The second lens is a lens having negative refractive power with a concave surface facing the object side,
The third lens is a lens having a negative refractive power,
An imaging lens having a three-lens structure characterized by satisfying the following conditional expression.
0.22 <(D3 + D4) / f <0.43 (3)
f3 / f <−0.4 and −5.6 <f2 / f <−3.3 (10)
However,
f: Focal length of the entire system f2: Focal length of the second lens f3: Focal length of the third lens D3: Surface distance on the optical axis between the rear surface of the first lens and the front surface of the second lens D4: Center of the second lens Thickness. In order from the object side, an aperture stop, a first lens, a second lens, and a third lens are disposed,
The first lens is a positive lens having a convex surface facing the object side,
The second lens is a lens having a concave surface facing the object side,
The third lens is a lens having a negative refractive power,
An imaging lens having a three-lens structure characterized by satisfying the following conditional expression.
0.22 <(D3 + D4) / f <0.43 (3)
f3 / f <−1.66 and 0.1 <| f1 / f2 | <0.5 (11)
However,
f: Focal length of the entire system f1: Focal length of the first lens f2: Focal length of the second lens f3: Focal length of the third lens D3: Surface on the optical axis between the rear surface of the first lens and the front surface of the second lens Interval D4: The center thickness of the second lens. In order from the object side, an aperture stop, a first lens, a second lens, and a third lens are disposed,
The first lens is a positive lens having a convex surface facing the object side,
The second lens is a lens having a concave surface facing the object side,
An imaging lens having a three-lens structure characterized by satisfying the following conditional expression.
−0.85 <f2 / {f3 · (45−νd2)} <− 0.13 (12)
However,
νd2: Abbe number of the second lens f2: focal length of the second lens f3: focal length of the third lens The three-element imaging lens according to claim 17, further satisfying the following conditional expression.
BR2 <0 (2)
However,
BR2: The light ray direction is positive, the distance from the optical axis apex position P1 on the front surface of the second lens to the position P2 where the light beam to the image height corner passes on the rear surface of the second lens is A, and the center thickness of the second lens is D4 BR2 = A / D4
And The three-element imaging lens according to claim 17, further satisfying the following conditional expression.
0.22 <(D3 + D4) / f <0.43 (3)
D6 / f ≦ 0.155 (8)
However,
f: Focal length of the entire system D3: Surface distance on the optical axis between the rear surface of the first lens and the front surface of the second lens D4: Center thickness of the second lens D6: Center thickness of the third lens. The three-element imaging lens according to claim 17, further satisfying the following conditional expression.
D4 / f <0.136 (6)
However,
f: focal length of entire system D4: center thickness of the second lens. In order from the object side, an aperture stop, a first lens having a positive refractive power, a second lens having a positive refractive power, and a third lens having a negative refractive power are disposed.
In the third lens, the object side surface is concave in the vicinity of the optical axis, and the image side surface is convex in the periphery.
An imaging lens having a three-lens structure characterized by satisfying the following conditional expression.
f / R6 <−0.4 (13)
However,
R6: Paraxial radius of curvature of the object side surface of the third lens f: The focal length of the entire system. The three-element imaging lens according to claim 21, further satisfying the following conditional expression.
-1.2 <f3 / f <0.0 (14)
However,
f3: The focal length of the third lens. The three-element imaging lens according to claim 21, further satisfying the following conditional expression.
0.22 <(D3 + D4) / f <0.43 (3)
However,
D3: Surface distance on the optical axis between the rear surface of the first lens and the front surface of the second lens. D4: The center thickness of the second lens. The three-element imaging lens according to claim 21, further satisfying the following conditional expression.
0 <f2 / f <1 (9)
However,
f2: The focal length of the second lens. 25. The three-lens imaging lens according to claim 24, further satisfying the following conditional expression.
νd2> 40 and −1.2 <f3 / f <0.0 (4)
However,
νd2: Abbe number of the second lens f3: The focal length of the third lens. In order from the object side, an aperture stop, a first lens having a positive refractive power, a second lens having a positive refractive power, and a third lens having a negative refractive power are disposed.
An imaging lens having a three-lens structure characterized by satisfying the following conditional expression.
D4 / f <0.136 (6)
−0.85 <f2 / {f3 · (45−νd2)} <− 0.13 (12)
-2.5 <f / f3 <0.0 and 0.5 <f2 / f (15)
However,
D4: center thickness of the second lens νd2: Abbe number of the second lens f: focal length of the entire system f2: focal length of the second lens f3: focal length of the third lens An imaging lens according to any one of claims 1 to 26;
An image pickup device that outputs an image pickup signal corresponding to an optical image formed by the image pickup lens.   A mobile terminal device comprising the camera module according to claim 27.

Images