JP2008076594A - Imaging lens, camera module, and portable terminal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact high performance imaging lens for excellently correcting image face curvature, comatic aberration, etc. by coping with ever increasing pixels, and to provide a camera module mounting the imaging lens and a portable terminal device. <P>SOLUTION: An imaging lens includes a first positive lens G1 in which both faces are aspheric, a second negative lens G2 in which both faces are aspheric, and a third positive lens G3 in which both faces are aspheric. The face of an object side makes the first lens G1 a projection shape on the object side in the neighborhood of an optical axis, the face of the object side makes the second lens G2 a recess shape on the object side in the neighborhood of the optical axis, the face of the object side makes the third lens G3 a projection shape on the object side in the neighborhood of the optical axis, and the face of an image side is made a recessed shape on the image side in the neighborhood of the optical axis. Condition inequality (1): 1.5<f/f3 and condition inequality (2): f2/f1<-0.62 are satisfied. Wherein, f is entire system focal distance, f1 is focal distance of the first lens, f2 is focal distance of the second lens and f3 is focal distance 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. Conventionally, for example, a three-lens lens has been developed as a small imaging lens mounted on a camera-equipped mobile phone (see Patent Documents 1 to 3).
Japanese Patent Laid-Open No. 2004-4466 JP 2004-226487 A JP 2004-240063 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, the conventional three-lens imaging lens has a large field curvature and coma, and improvements are desired.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a compact and high-performance imaging lens in which field curvature, coma and the like are well corrected in response to an increase in the number of pixels, and the imaging lens. Is to provide a camera module and a portable terminal device capable of obtaining a high-resolution imaging signal.

The imaging lens according to the present invention includes, in order from the object side, a first lens having both aspheric surfaces and positive refractive power, a second lens having both surfaces aspheric and negative refractive power, and both surfaces aspheric. And a third lens having a positive refractive power. In addition, the first lens has a convex surface on the object side near the optical axis, the second lens has a concave shape on the object side near the optical axis, and the third lens The object side surface has a convex shape on the object side near the optical axis, and the image side surface has a concave shape on the image side near the optical axis, which satisfies the following conditional expression.
1.5 <f / f3 (1)
f2 / f1 <−0.62 (2)
Here, 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, and f3 is the focal length of the third lens.

  In the imaging lens according to the present invention, the shape and refractive power of each lens are made appropriate with a small number of lenses, ie, three as a whole, thereby achieving downsizing and high performance. In particular, by satisfying each conditional expression, the power balance between the lenses is optimized, which is advantageous for correction of curvature of field, coma, and the like, and high optical performance corresponding to an increase in the number of pixels can be obtained.

The imaging lens according to the present invention more preferably satisfies the following conditional expression. Thereby, higher optical performance can be obtained.
1.5 <f / f3 <2.0 (1A)
−0.80 <f2 / f1 <−0.62 (2A)
0.4 <f1 / f <1.2 (3)

  In the imaging lens according to the present invention, an aperture stop may be provided on the object side of the first lens. Thereby, the shortening of the total length 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), and optical performance advantageous to the characteristics of the imaging device can be obtained.

In the imaging lens according to the present invention, it is preferable that the material of the first lens and the third lens has an Abbe number of 50 or more, and the material of the second lens has an Abbe number of 30 or less.
Thereby, it is advantageous to correct axial and magnification chromatic aberration, and better resolution performance can be obtained.

A camera module according to the present invention includes an 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 the high-resolution optical image obtained by the imaging lens of 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 imaging lens of the present invention, and a high-resolution image is obtained based on the imaging signal. .

  According to the imaging lens of the present invention, the shape and refractive power of each lens are optimized with a small number of lenses of three as a whole, so that field curvature, coma aberration, etc. correspond to the increase in the number of pixels. A small and high-performance imaging lens system that is well corrected can be realized.

  In addition, according to the camera module or the portable terminal device of the present invention, since an electrical signal corresponding to the optical image formed by the high-performance imaging lens of the present invention is output, a high-resolution imaging signal is output. Obtainable. 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. 7A and 7B) described later. FIG. 2 shows a second configuration example and corresponds to a lens configuration of a second numerical example (FIGS. 8A and 8B) which will be described later. FIG. 3 shows a third configuration example, which corresponds to a lens configuration of a third numerical example (FIGS. 9A and 9B) which will be described later. FIG. 4 shows a fourth configuration example, which corresponds to a lens configuration of a fourth numerical example (FIGS. 10A and 10B) which will be described later. FIG. 5 shows a fifth configuration example and corresponds to a lens configuration of a fifth numerical example (FIGS. 11A and 11B) which will be described later. FIG. 6 shows a sixth configuration example, which corresponds to a lens configuration of a sixth numerical example (FIGS. 12A and 12B) described later. In FIG. 1 to FIG. 6, the symbol Ri is the curvature of the i-th surface that is numbered sequentially so as to increase toward the image side (imaging side), with the surface of the component closest to the object side first. Indicates the radius. 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.

  This imaging lens is suitable for use in various imaging devices using an imaging device such as a CCD or CMOS, in particular, relatively small portable terminal devices such as digital still cameras, camera-equipped mobile phones, and PDAs. . 26A and 26B show a mobile phone with a camera as an example of a mobile terminal device. This camera-equipped cellular 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. 26B), a display unit 22 (FIG. 26A), 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. 27 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 6, the imaging lens according to the present embodiment includes a first lens G1, a second lens G2, and a third lens G3 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. 1 to 6, the aperture stop St is disposed on the front side of the first lens G1 and on the most object side of the lens system. An imaging element 10 such as a CCD is disposed on the imaging surface of the imaging lens. Various optical members are arranged between the third lens G3 and the image sensor 10 according to the configuration of the camera side on which 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 G1, the second lens G2, and the third lens G3 is aspheric on both surfaces. The first lens G1, the second lens G2, and the third lens G3 are preferably made of plastic. In addition, the material of the first lens and the third lens preferably has an Abbe number of 50 or more, and the material of the second lens preferably has an Abbe number of 30 or less.

  The first lens G1 has a positive refractive power. The object side surface of the first lens G1 is convex toward the object side in the vicinity of the optical axis. In the first configuration example (FIG. 1) and the fourth configuration example (FIG. 4), the image side surface of the first lens G1 has a concave shape on the image side in the vicinity of the optical axis, and a positive meniscus lens in the vicinity of the optical axis. It becomes the composition of. In the second, third, fifth, and sixth configuration examples (FIGS. 2, 3, 5, and 6), the image side surface of the first lens G1 has a convex shape on the image side in the vicinity of the optical axis. In the vicinity of the optical axis, a biconvex lens is formed.

  The second lens G2 has a negative refractive power. The object side surface of the second lens G2 has a concave shape on the object side in the vicinity of the optical axis. In the first, fourth, fifth, and sixth configuration examples, the image side surface of the second lens G2 has a concave shape on the image side in the vicinity of the optical axis, and has a biconcave lens configuration in the vicinity of the optical axis. Yes. In the second and third configuration examples, the image-side surface of the second lens G2 has a convex shape on the image side in the vicinity of the optical axis, and has a negative meniscus lens configuration in the vicinity of the optical axis.

  The third lens G3 has a positive refractive power. The object side surface of the third lens G3 is convex toward the object side in the vicinity of the optical axis. For example, the image-side surface of the third lens G3 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.

  Here, the third lens G3 is a lens arranged closest to the imaging surface. Therefore, in the third lens G3, the luminous flux is separated at each angle of view as compared with the first lens G1 and the second lens G2. Therefore, by appropriately using an aspheric surface in the third lens G3, 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 G3 in the vicinity of the optical axis is different from the shape in the peripheral portion. Specifically, it is preferable that the object side surface of the third lens G3 has, for example, a convex shape in the vicinity of the optical axis and a concave shape in the peripheral portion. Further, it is preferable that the image-side surface has, for example, a concave shape in the vicinity of the optical axis and a convex shape in the peripheral portion.

This imaging lens satisfies the following conditions.
1.5 <f / f3 (1)
f2 / f1 <−0.62 (2)
Here, f is the focal length of the entire system, f1 is the focal length of the first lens G1, f2 is the focal length of the second lens G2, and f3 is the focal length of the third lens G3.

Conditional expressions (1) and (2) are preferably in the numerical ranges of the following conditional expressions (1A) and (2A). Moreover, it is preferable to satisfy the conditional expression (3).
1.5 <f / f3 <2.0 (1A)
−0.80 <f2 / f1 <−0.62 (2A)
0.4 <f1 / f <1.2 (3)

Further, it is more preferable that the numerical values are in the following conditional expressions (1B) and (2B).
1.5 <f / f3 <1.6 (1B)
−0.67 <f2 / f1 <−0.62 (2B)

Next, operations and effects of the imaging lens configured as described above will be described.
In this imaging lens, since the shape and refractive power of each lens are appropriate with a small lens configuration of three as a whole, miniaturization and high performance can be achieved. In particular, by satisfying each conditional expression, the power balance between the lenses is optimized, which is advantageous for correction of curvature of field, coma, and the like, and high optical performance corresponding to an increase in the number of pixels can be obtained.

  When the upper limit of conditional expression (1A) is exceeded, it becomes difficult to correct curvature of field and coma, and good optical performance cannot be obtained. Therefore, more preferable optical performance can be obtained by setting the upper limit in the range of the conditional expression (1B). When the lower limit of conditional expressions (1), (1A), and (1B) is exceeded, the positive power of the first lens G1 increases or the negative power of the second lens G2 decreases, resulting in spherical aberration and field curvature. This is not preferable because it becomes difficult to correct coma aberration and chromatic aberration at the same time.

  If the upper limit of conditional expressions (2), (2A), (2B) is exceeded, the negative power of the second lens G2 is too strong compared to the positive power of the first lens G1, and spherical aberration, curvature of field, It becomes difficult to correct coma and chromatic aberration at the same time. Exceeding the lower limit of conditional expression (2A) is not preferable because it becomes difficult to correct curvature of field and coma, and good optical performance cannot be obtained. Therefore, more preferable optical performance can be obtained by setting the lower limit to the range of the conditional expression (2B).

  If the upper limit of conditional expression (3) is exceeded, chromatic aberration will be undercorrected. Exceeding the lower limit of conditional expression (3) is not preferable because the power of the first lens G1 and the second lens G2 is increased, and high component accuracy and assembly accuracy are required.

  Further, in this imaging lens, the material of the first lens G1, the second lens G2, and the third lens G3 is made of plastic, so that an aspherical shape can be realized with high accuracy, and light weight and low cost can be realized. It becomes possible to provide a lens. Also, by setting the Abbe number of the material of the first lens G1 and the third lens G3 to 50 or more and the Abbe number of the material of the second lens G2 to 30 or less, both axial chromatic aberration and magnification chromatic aberration are corrected well. And good resolution is obtained.

  Further, in this imaging lens, by arranging the aperture stop St on the front side of the first lens G1, 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 principal ray on the image sensor 10 is almost parallel to the optical axis in order to support the high-pixel image sensor 10 (the incident angle on the image plane is relative to the normal of the image plane). To be close to zero). In this imaging lens, for example, the image-side surface of the third lens G3 that is the final lens surface closest to the imaging element 10 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 is appropriately performed for each angle of view, and the incident angle of the light beam on the image sensor 10 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.

  As described above, according to the imaging lens according to the present embodiment, since the shape and refractive power of each lens are optimized with a small number of lenses of three as a whole, it corresponds to an increase in the number of pixels. Thus, a compact and high-performance imaging lens system in which curvature of field, coma aberration, etc. are corrected well can be realized. 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 sixth 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. 7A and 7B. In particular, FIG. 7A shows the basic lens data, and FIG. 7B shows data relating to the aspherical surface. In the field of the surface number Si in the lens data shown in FIG. 7A, the surface of the component closest to the object side is the first, and the i th ( The number of the surface of i = 1 to 6) 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. Nej represents the value of the refractive index with respect to the e-line (wavelength 546.07 nm) of the j-th (j = 1 to 3) optical element from the object side. In the column νdj, the Abbe number value for the d-line (wavelength 587.6 nm) of the j-th optical element from the object side is shown.

  Although omitted in the lens data of FIG. 7A, the imaging lens according to Example 1 has a glass plate GC with a thickness of 0.3 mm disposed between the third lens L3 and the imaging plane. ing.

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. The basic lens data in FIG. 7A shows numerical values of the radius of curvature near the optical axis as the radius of curvature of these aspheric surfaces. In the numerical values shown as aspherical data in FIG. 7B, the symbol “E” indicates that the next 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 K 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, each aspheric surface is expressed by effectively using the _{third to twentieth} coefficients B _{3 to} B ₂₀ as the aspheric coefficient B _n .
Z = C · Y ² / {1+ (1−K · 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)
K: Conic constant C: Paraxial curvature = 1 / R
(R: paraxial radius of curvature)
B _n : nth-order aspheric coefficient

  Similar to the imaging lens according to Example 1 above, specific lens data corresponding to the configuration of the imaging lens shown in FIG. 2 is shown as Example 2 in FIGS. 8A and 8B. . Similarly, specific lens data corresponding to the configuration of the imaging lens shown in FIG. 3 is shown as Example 3 in FIGS. 9A and 9B. Similarly, specific lens data corresponding to the configuration of the imaging lens shown in FIG. 4 is shown as Example 4 in FIGS. 10A and 10B. Similarly, specific lens data corresponding to the configuration of the imaging lens shown in FIG. 5 is shown as Example 5 in FIGS. 11A and 11B. Similarly, specific lens data corresponding to the configuration of the imaging lens shown in FIG. 6 is shown as Example 6 in FIGS. 12A and 12B.

  In any of the imaging lenses according to Examples 2 to 6, as in Example 1, both surfaces of the first lens L1, the second lens L2, and the third lens L3 are all aspherical. . Although not shown in each lens data, a glass plate GC having a thickness of 0.3 mm is disposed between the third lens L3 and the imaging plane for each of the second to sixth embodiments.

  In FIG. 13, the values related to the above-described conditional expressions (1) to (3) (conditional expressions (1A), (2A) and (1B), (2B)) are collectively shown for the respective examples. As various data, FNo. The values of (F value), f (focal length of the entire system), Bf (back focus), and ω (half angle of view) are collectively shown for each example. As can be seen from FIG. 13, the value of each example is within the numerical range of each conditional expression.

  14A to 14D show spherical aberration, astigmatism, distortion (distortion aberration), and lateral chromatic aberration in the imaging lens according to Example 1, respectively. 15A to 15C show transverse aberration (coma aberration) at each angle of view. Each aberration diagram shows an aberration with the e-line as a reference wavelength. The spherical aberration diagram and the lateral chromatic aberration diagram also show aberrations for the g-line (wavelength 435.8 nm) and the C-line (wavelength 656.3 nm). In the astigmatism diagram, the solid line indicates the sagittal direction and the broken line indicates the tangential direction. FNo. Indicates an F value, and ω indicates a half angle of view.

  Similarly, various aberrations of the imaging lens according to Example 2 are shown in FIGS. 16A to 16D and FIGS. 17A to 17C, and the imaging lens according to Example 3 is shown. The various aberrations are shown in FIGS. 18A to 18D and FIGS. 19A to 19C. Similarly, various aberrations regarding the imaging lens according to Example 4 are illustrated in FIGS. 20A to 20D and FIGS. 21A to 21C, and the imaging lens according to Example 5 is illustrated. Various aberrations are shown in FIGS. 22 (A) to 22 (D) and FIGS. 23 (A) to 23 (C), and various aberrations of the imaging lens according to Example 6 are shown in FIGS. 24 (A) to 24 (D). ) And FIGS. 25 (A) to 25 (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. 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 5 of this invention, (A) shows basic lens data, (B) shows the lens data regarding an aspherical surface. It is the figure which showed various data, such as the value regarding a conditional expression, about each Example collectively. 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, (C) shows distortion, and (D) shows lateral chromatic aberration. FIG. 6 is an aberration diagram showing lateral aberration of the imaging lens according to Example 1 of the invention. 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, (D) shows lateral chromatic aberration. FIG. 6 is an aberration diagram showing lateral aberration of the imaging lens according to Example 2 of the present invention. 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, (D) shows lateral chromatic aberration. FIG. 6 is an aberration diagram showing lateral aberration of the imaging lens according to Example 3 of the present invention. 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, (D) shows lateral chromatic aberration. FIG. 6 is an aberration diagram showing lateral aberration of the imaging lens according to Example 4 of the present invention. 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, (D) shows lateral chromatic aberration. FIG. 10 is an aberration diagram showing lateral aberration of the imaging lens according to Example 5 of the present invention. 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, (D) shows lateral chromatic aberration. FIG. 10 is an aberration diagram showing lateral aberration of the imaging lens according to Example 6 of the present invention. 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, G1 ... 1st lens, G2 ... 2nd lens, G3 ... 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 (6)

In order from the object side, both surfaces are aspherical and have a positive refractive power, a second lens having both aspherical surfaces and negative refractive power, and both surfaces are aspherical and have positive refractive power. A third lens having,
In the first lens, the object side surface is convex toward the object side in the vicinity of the optical axis,
In the second lens, the object side surface is concave on the object side in the vicinity of the optical axis,
The third lens has a convex surface on the object side near the optical axis, and a concave surface on the image side near the optical axis.
An imaging lens that satisfies the following conditional expression.
1.5 <f / f3 (1)
f2 / f1 <−0.62 (2)
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 The imaging lens according to claim 1, further satisfying the following conditional expression.
1.5 <f / f3 <2.0 (1A)
−0.80 <f2 / f1 <−0.62 (2A)
0.4 <f1 / f <1.2 (3) The imaging lens according to claim 1, wherein an aperture stop is provided on the object side of the first lens. The material of the first lens and the third lens has an Abbe number of 50 or more,
The imaging lens according to any one of claims 1 to 3, wherein the material of the second lens has an Abbe number of 30 or less. The imaging lens according to any one of claims 1 to 4,
An image pickup device that outputs an electrical signal corresponding to an optical image formed by the image pickup lens.   A mobile terminal device comprising the camera module according to claim 5.

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