JPWO2015005417A1 - Imaging lens, imaging device, and portable terminal - Google Patents

Abstract

Provided is a five-lens imaging lens that is small but has various aberrations corrected satisfactorily and has a brightness such that the F-number is F2.4 or less. The imaging lens 10 includes, in order from the object side, a first lens L1 having a positive refractive power and a convex surface facing the object side in the vicinity of the optical axis AX, and a negative lens having a negative refractive power on the object side in the vicinity of the optical axis AX. A second lens L2 having a meniscus shape with a concave surface, a third lens L3, a fourth lens L4 having a positive refractive power, and a fifth lens having a negative refractive power and a biconcave shape in the vicinity of the optical axis AX. It consists essentially of the lens L5. The imaging lens 10 satisfies the following conditional expressions (1) and (2) 0.55 <f1 / f <0.95 (1), 0.35 <d14 / EPD <0.55 (2) . Here, f1 is the focal length of the first lens L1, f is the focal length of the entire imaging lens 10, and d14 is the optical axis from the object side surface S11 of the first lens L1 to the image side surface S22 of the second lens L2. The distance on AX, and EPD is the diameter of the entrance pupil of the entire imaging lens 10 system.

Description

  The present invention relates to a small imaging lens, an imaging apparatus including the same, and a portable terminal.

  In recent years, along with the improvement in performance and miniaturization of imaging devices using solid-state imaging devices such as CCD (Charge Coupled Device) type image sensors or CMOS (Complementary Metal Oxide Semiconductor) type image sensors, Portable information terminals are becoming popular. In addition, there is an increasing demand for further downsizing and higher performance of imaging lenses mounted on these imaging apparatuses. As an imaging lens for such an application, an imaging lens having a five-lens configuration has been proposed because it can achieve higher performance than a lens having three or four lenses.

  As such a five-lens imaging lens, a first lens having positive refractive power in order from the object side, a second lens having negative refractive power with a convex surface facing the image side, and a third lens having negative refractive power. An imaging lens including a lens, a fourth lens having a positive refractive power, and a fifth lens having a negative refractive power is disclosed (for example, see Patent Documents 1 and 2).

However, the imaging lens described in Patent Document 1 has a long back focus with respect to the entire optical length, and as a result, it is difficult to say that the imaging lens can be sufficiently downsized. Further, the F value is as dark as about F2.8, and it cannot cope with the recent increase in the number of pixels.
In addition, the imaging lens described in Patent Document 2 cannot be said to have sufficient aberration correction as a whole, and the F value is as dark as about F2.4, so that higher performance is achieved when the aperture is further increased. Difficult to do.

JP 2010-152042 A US Patent Application Publication No. 2013/0057968

  The present invention has been made in view of the above-mentioned problems of the background art, and has a brightness with an F value of F2.4 or less, in which various aberrations are well corrected while being smaller than the conventional type. An object of the present invention is to provide an imaging lens having a five-lens configuration.

Here, although it is a scale of a small imaging lens, the present invention aims at miniaturization at a level satisfying the following expression. By satisfying this range, the entire imaging apparatus can be reduced in size and weight.
L / 2Y <0.90 (10)
However,
L: Distance on the optical axis from the lens surface closest to the object side to the image-side focal point of the entire imaging lens system 2Y: Diagonal length of the imaging surface of the imaging device (diagonal length of the rectangular effective pixel area of the imaging device)

  Here, the image-side focal point refers to an image point when a parallel light beam parallel to the optical axis is incident on the imaging lens. When a parallel plate such as an optical low-pass filter, an infrared cut filter, or a seal glass of the image pickup device package is disposed between the most image side surface of the image pickup lens and the image side focal position, the parallel plate is used. The part is assumed to be the air conversion distance and the value of L is calculated.

The value L / 2Y is more preferably in the range of the following formula.
L / 2Y <0.80 (10) ′

In order to achieve the above object, an imaging lens according to the present invention is for imaging a subject image on an imaging surface of an imaging element, and in order from the object side, (a) has a positive refractive power, A first lens having a convex surface facing the object side near the optical axis and a curvature that is stronger on the object side surface than the image side surface; and (b) having a negative refractive power and directing a concave surface toward the object side near the optical axis. A second lens having a meniscus shape or a concave shape near the optical axis on the object side, (c) a third lens, (d) a fourth lens having a positive refractive power, and (e) a negative refractive power. And (f) the aperture stop is disposed closer to the object side than the second lens, and (g) the image side surface of the second lens is (B) The sag amount on the object side surface of the third lens has a negative value at the peripheral part. (I) the image side surface of the fifth lens has an aspherical shape, has an extreme value at a position other than the intersection of the optical axis, to satisfy the following condition (j).
0.55 <f1 / f <0.95 (1)
0.35 <d14 / EPD <0.55 (2)
However,
f1: Focal length of the first lens f: Focal length of the entire imaging lens system (hereinafter the same)
d14: Distance on the optical axis from the object side surface of the first lens to the image side surface of the second lens EPD: entrance pupil diameter of the entire imaging lens system (the same applies hereinafter)

  The basic configuration according to the present invention for obtaining a compact imaging lens with good aberration correction is, in order from the object side, having a positive refractive power, with the convex surface facing the object side in the vicinity of the optical axis, and from the image side surface. A first lens having a stronger curvature on the object side, a second lens having a negative refractive power and a concave surface facing the object side in the vicinity of the optical axis, a third lens, a positive lens, and a positive refraction A fourth lens having a power and a fifth lens having a negative refractive power and a biconcave shape in the vicinity of the optical axis. This lens configuration of a so-called telephoto type in which a positive lens group including a first lens, a second lens, a third lens, and a fourth lens is disposed, and a negative fifth lens is disposed on the image side of the positive lens group. This is an advantageous configuration for reducing the overall length of the imaging lens.

Further, in the above imaging lens, by using two or more of the five lens elements as negative lenses, the number of surfaces having a diverging action can be increased to facilitate correction of Petzval sum, and good imaging performance up to the periphery of the screen can be achieved. It is possible to obtain a secured imaging lens. In addition, by making the object side surface of the first lens a convex surface and making the object side surface have a curvature that is stronger than the image side surface, the combined principal point position of the entire imaging lens system can be brought closer to the object side, This is advantageous for reducing the overall length of the imaging lens. Furthermore, the shape of the object side surface of the second lens can be made concentric with the aperture stop by making the second lens a meniscus shape or a concave flat shape with the concave surface facing the object side in the vicinity of the optical axis. Further, off-axis aberrations generated on the object side surface of the second lens can be suppressed.
In the imaging lens, by making the image side surface of the second lens have a diverging action at the peripheral portion, it is possible to satisfactorily correct field curvature, distortion, lateral chromatic aberration, and the like with respect to ambient light. Become. Here, the “shape having a diverging action” refers to a surface on which light incident on the image side surface of the second lens exits in a direction away from the optical axis after passing through the image side surface of the second lens. By setting the sag amount on the object side surface of the third lens to a negative value in the peripheral portion, the shape of the object side surface of the third lens can be made concentric with respect to the aperture stop, similarly to the second lens. Therefore, various off-axis aberrations occurring on the object side surface of the third lens can be suppressed. Here, the “sag amount” is the amount of displacement from the surface vertex on the optical axis at the height h from the optical axis of the optical surface. The fact that the sag amount takes a negative value at a certain height h means that the displacement amount of the surface at the height h is located closer to the object side than the point on the optical axis.
In the imaging lens, by making the image side surface of the fifth lens disposed closest to the image side an aspherical surface, various aberrations at the periphery of the screen can be favorably corrected. Furthermore, the aspherical shape having an extreme value at a position other than the intersection with the optical axis makes it easy to ensure the telecentric characteristics of the image-side light beam. Here, “extreme value” is a line or point on the aspheric surface where the tangent plane or tangent of the aspherical vertex is a plane or line segment perpendicular to the optical axis in the curve of the lens cross-sectional shape within the effective radius. That is.

In the imaging lens, conditional expression (1) is a conditional expression for appropriately setting the focal length of the first lens to appropriately shorten the entire imaging lens and correct aberrations.
When the value f1 / f of conditional expression (1) is less than the upper limit, the refractive power of the first lens can be maintained moderately, and the composite principal point from the first lens to the fourth lens is arranged closer to the object side. And the overall length of the imaging lens can be shortened. On the other hand, when the value f1 / f of conditional expression (1) exceeds the lower limit, the refractive power of the first lens does not become excessively large, and higher-order spherical aberration and coma aberration that occur in the first lens are reduced. It can be kept small.
The value f1 / f is more preferably in the range of the following formula.
0.60 <f1 / f <0.90 (1) ′

In the imaging lens, the conditional expression (2) is a conditional expression for appropriately setting the distance on the optical axis from the object side surface of the first lens to the image side surface of the second lens.
As described above, the image side surface of the second lens is a surface having a diverging action at the peripheral portion, and in order to correct field curvature and chromatic aberration more favorably, a diverging surface is arranged at a place where the beam diameter is large. Is desirable. That is, it is desirable to arrange the second lens closer to the object side. On the other hand, since it is necessary to secure a certain amount of lens thickness in the periphery of the first lens adjacent to the aperture stop, a center diameter of the first lens tends to be large in a large aperture lens having a small F value. Thus, there is a limit in moving the second lens toward the object side. Therefore, by satisfying conditional expression (2), the second lens can be arranged at an optimal position, and both downsizing of the entire length of the imaging lens and good aberration correction can be achieved.
Specifically, when the value d14 / EPD of conditional expression (2) is lower than the upper limit, the image side surface of the second lens having a diverging action can be arranged closer to the object side, so that aberration correction is performed. It can be done well. In addition, since the total value of the thickness of the first lens and the thickness of the second lens can be reduced, the overall length of the imaging lens can be shortened as a result. On the other hand, when the value d14 / EPD of conditional expression (2) exceeds the lower limit, the second lens does not go too far toward the object side, and the thickness of the peripheral portion of the first lens and the center thickness of the second lens are reduced. The moldability is not impaired.
The value d14 / EPD is more preferably in the range of the following formula.
0.40 <d14 / EPD <0.53 (2) ′

In a specific aspect of the present invention, the following conditional expression (3) is satisfied in the imaging lens.
0.30 <r1 / f <0.50 (3)
However,
r1: radius of curvature of the object side surface of the first lens

Conditional expression (3) is a conditional expression for appropriately setting the radius of curvature of the object side surface of the first lens and appropriately achieving shortening of the entire length of the imaging lens and aberration correction.
When the value of conditional expression (3) is below the upper limit, the refractive power of the object side surface of the first lens can be maintained moderately, and the composite principal point of the first lens and the second lens is arranged closer to the object side. And the overall length of the imaging lens can be shortened. On the other hand, when the value of conditional expression (3) exceeds the lower limit, the refractive power of the object side surface of the first lens does not become excessively large, and higher-order spherical aberration and coma aberration that occur in the first lens are reduced. It can be kept small.
The value r1 / f is more preferably in the range of the following formula.
0.35 <r1 / f <0.45 (3) ′

In another aspect of the present invention, the following conditional expression (4) is satisfied.
−1.20 <f / f23 <−0.15 (4)
However,
f23: Composite focal length of the second lens and the third lens

Conditional expression (4) is a conditional expression for appropriately setting the combined focal length of the second lens and the third lens.
When the value of conditional expression (4) exceeds the lower limit, the negative combined refractive power of the second lens and the third lens does not become too strong, and the combined principal point position of the entire imaging lens system is arranged on the image side. And the overall length of the imaging lens can be shortened. On the other hand, since the negative combined refractive power of the second lens and the third lens can be appropriately maintained when the value of conditional expression (4) is below the upper limit, the Petzval sum can be easily corrected, and the periphery of the screen It is possible to obtain an imaging lens that ensures good imaging performance.
The value f / f23 is more preferably in the range of the following formula.
−1.10 <f / f23 <−0.20 (4) ′

In still another aspect of the present invention, the following conditional expression (5) is satisfied.
−2.0 <(r3 + r4) / (r3−r4) ≦ −1.0 (5)
However,
r3: radius of curvature of object side surface of second lens r4: radius of curvature of image side surface of second lens

Conditional expression (5) is a conditional expression for appropriately setting the shape of the second lens. In the range indicated by conditional expression (5), the second lens changes from a plano-concave shape with a concave surface facing the object side to a meniscus shape with the concave surface facing the object side.
When the value of conditional expression (5) is below the upper limit, the curvature of the concave surface on the object side can be increased, so the second lens can be made more concentric with the aperture stop, and the second lens Off-axis aberrations occurring on the object side surface of the object can be suppressed. On the other hand, if the value of conditional expression (5) exceeds the lower limit, the radius of curvature of the object side surface of the second lens does not become too small, and a clearance with the first lens can be appropriately secured. As a result, the overall length of the imaging lens can be shortened.
The value (r3 + r4) / (r3-r4) is more preferably in the range of the following formula.
−1.8 <(r3 + r4) / (r3−r4) ≦ −1.0 (5) ′

  In still another aspect of the present invention, the sag amount on the image side surface of the third lens is a negative value in the peripheral portion. Thereby, since it can be made concentric with respect to the aperture stop together with the object side surface, various off-axis aberrations generated in the entire third lens can be suppressed.

  In still another aspect of the present invention, the third lens has negative refractive power. As a result, it is possible to increase the number of lenses having negative refractive power in combination with the second lens and the fifth lens. Therefore, it is possible to easily correct the Petzval sum by increasing the diverging surface and to improve the periphery of the screen. It is possible to obtain an imaging lens that ensures imaging performance.

  In still another aspect of the present invention, the third lens has a shape in which a concave surface faces the image side in the vicinity of the optical axis. Accordingly, the negative refractive power of the third lens can be set strongly, which is more advantageous for correction of field curvature and chromatic aberration.

In still another aspect of the present invention, the following conditional expression (6) is satisfied.
0.0 <| f2 / f3 | <1.00 (6)
However,
f2: focal length of the second lens f3: focal length of the third lens

Conditional expression (6) is a conditional expression for appropriately setting the ratio of the focal lengths of the second lens and the third lens. Since the value of conditional expression (6) is lower than the upper limit, the refractive power of the second lens can be set to be stronger than that of the third lens. This is advantageous for reducing curvature and chromatic aberration. On the other hand, if the value of conditional expression (6) exceeds the lower limit, the negative refractive power can be appropriately shared between the second lens and the third lens, so that a manufacturing error occurs in each lens. It becomes possible to suppress the performance degradation of the device.
The value | f2 / f3 | is more preferably in the range of the following formula.
0.0 <| f2 / f3 | <0.90 (6) ′

In still another aspect of the present invention, the following conditional expression (7) is satisfied.
15 <ν3 <45 (7)
However,
ν3: Abbe number of the third lens

Conditional expression (7) is a conditional expression for satisfactorily correcting the chromatic aberration by appropriately setting the Abbe number of the third lens. By using a high dispersion material that falls within the range of conditional expression (7) for the third lens, it becomes possible to satisfactorily correct the chromatic aberration of the entire imaging lens system.
The value ν3 is more preferably in the range of the following formula.
20 <ν3 <28 (7) ′

In still another aspect of the present invention, the following conditional expression (8) is satisfied.
20 <ν1-ν2 <70 (8)
However,
ν1: Abbe number of the first lens ν2: Abbe number of the second lens

Conditional expression (8) is a conditional expression for satisfactorily correcting the chromatic aberration of the entire imaging lens system. When the value of conditional expression (8) exceeds the lower limit, chromatic aberrations such as axial chromatic aberration and lateral chromatic aberration can be corrected in a well-balanced manner. On the other hand, when the value of conditional expression (8) is below the upper limit, it can be made of an easily available glass material.
The value ν1-ν2 is more preferably in the range of the following formula.
25 <ν1-ν2 <65 (8) ′

In still another aspect of the present invention, the following conditional expression (9) is satisfied.
f / EPD <1.95 (9)

By using an optical system that satisfies the range of conditional expression (9), the amount of light incident on the sensor surface can be increased even in a recent optical system using a sensor with a narrow pixel pitch, and an image with little noise can be obtained even in a dark place. Can be obtained.
The value f / EPD is more preferably in the range of the following formula.
f / EPD <1.90 (9) ′

  In yet another aspect of the present invention, the aperture stop is disposed between the first lens and the second lens. Thereby, even if the radius of curvature of the object side surface of the first lens is reduced, the refraction angle of the peripheral marginal ray passing through the object side surface of the first lens does not become too large. Can be compatible.

  In still another aspect of the present invention, the aperture stop is disposed closer to the object side than the first lens. Thereby, since the refraction angle of the light beam on the object side surface of the first lens can be reduced, it is possible to suppress the occurrence of high-order spherical aberration and coma generated in the first lens. In addition, since the height of the light beam passing through the first lens can be reduced, the edge thickness of the first lens can be easily ensured, and the moldability can be improved. In particular, in an optical system having a large aperture, it is important to dispose the aperture stop closer to the object side than the first lens.

  In still another aspect of the present invention, the lens further includes a lens having substantially no power.

  In order to achieve the above object, an imaging apparatus according to the present invention includes the imaging lens described above and an imaging element. By using the image pickup lens of the present invention, it is possible to obtain an image pickup apparatus that has a wide angle and has a brightness such that the F value is F2.4 or less and is small and has various aberrations corrected satisfactorily.

  In order to achieve the above object, a mobile terminal according to the present invention includes an imaging device that has a brightness at a wide angle of F2.4 or less and is small and has various aberrations corrected satisfactorily.

It is a figure explaining an imaging device provided with the imaging lens of one embodiment of the present invention. It is a block diagram explaining a portable terminal provided with the imaging device of FIG. 3A and 3B are perspective views of the front side and the back side of the mobile terminal, respectively. 2 is a cross-sectional view of an imaging lens of Example 1. FIG. 5A to 5E are aberration diagrams of the imaging lens of Example 1. FIG. 6 is a cross-sectional view of an imaging lens of Example 2. FIG. 7A to 7E are aberration diagrams of the imaging lens of Example 2. FIG. 6 is a cross-sectional view of an imaging lens of Example 3. FIG. 9A to 9E are aberration diagrams of the imaging lens of Example 3. FIG. 6 is a cross-sectional view of an imaging lens of Example 4. FIG. 11A to 11E are aberration diagrams of the imaging lens of Example 4. FIGS. 6 is a cross-sectional view of an imaging lens of Example 5. FIG. 13A to 13E are aberration diagrams of the imaging lens of Example 5. FIGS.

  Hereinafter, with reference to FIG. 1 etc., the imaging lens which is one Embodiment of this invention is demonstrated. The imaging lens 10 illustrated in FIG. 1 has the same configuration as the imaging lens 11 of Example 1 described later.

  FIG. 1 is a cross-sectional view illustrating a camera module including an imaging lens according to an embodiment of the present invention.

  The camera module 50 includes an imaging lens 10 that forms a subject image, an imaging device 51 that detects a subject image formed by the imaging lens 10, and a wiring board 52 that holds the imaging device 51 from behind and has wiring and the like. And a lens barrel portion 54 having an opening OP for holding the imaging lens 10 and the like and allowing a light beam from the object side to enter. The imaging lens 10 has a function of forming a subject image on the image plane or the imaging plane (projected plane) I of the imaging element 51. The camera module 50 is used by being incorporated in an imaging device to be described later.

The imaging lens 10 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 in order from the object side.
The imaging lens 10 is small in size, and as a scale, it aims to be downsized to a level that satisfies the following expression (10).
L / 2Y <0.90 (10)
Here, L is the distance on the optical axis AX from the most object-side lens surface (object side surface S11 of the first lens L1) of the entire imaging lens 10 system to the image-side focal point, and 2Y is the imaging surface of the image sensor 51. The diagonal length (the diagonal length of the rectangular effective pixel region of the image sensor 51). The image-side focal point refers to an image point when parallel light rays parallel to the optical axis AX are incident on the imaging lens 10. When the value L / 2Y satisfies the range of the above formula (10), the entire camera module 50 can be reduced in size and weight.

It should be noted that an optical low-pass filter, an infrared cut filter, an image sensor package seal glass, or the like is provided between the image side lens surface (image side surface S52 of the fifth lens L5) of the imaging lens 10 and the image side focal position. When the parallel flat plate F is arranged, the value of L is calculated after the parallel flat plate F portion is set as an air conversion distance. The value L / 2Y is more preferably in the range of the following formula.
L / 2Y <0.80 (10) ′

  The image sensor 51 is a sensor chip made of a solid-state image sensor. The photoelectric conversion unit 51a of the image sensor 51 is composed of a CCD (charge coupled device) or a CMOS (complementary metal oxide semiconductor), photoelectrically converts incident light for each RGB, and outputs an analog signal thereof. The photoelectric conversion surface of the photoelectric conversion unit 51a as the light receiving unit is an image surface or an imaging surface (projected surface) I.

  The wiring board 52 has a role of aligning and fixing the image sensor 51 to other members (for example, the lens barrel portion 54). The wiring board 52 can receive a voltage and a signal for driving the image pickup device 51 and the driving mechanism 55a from an external circuit, and can output a detection signal to the external circuit.

  On the imaging lens 10 side of the imaging element 51, a parallel plate F is disposed and fixed by a holder member (not shown) so as to cover the imaging element 51 and the like.

  The lens barrel 54 houses and holds the imaging lens 10. The lens barrel portion 54 enables the focusing operation of the imaging lens 10 by moving any one or more of the lenses L1 to L5 constituting the imaging lens 10 along the optical axis AX. For example, it has a drive mechanism 55a. The drive mechanism 55a reciprocates a specific lens along the optical axis AX. The drive mechanism 55a includes, for example, a voice coil motor and a guide. The drive mechanism 55a can be configured by a stepping motor or the like instead of the voice coil motor or the like.

  Next, an example of a mobile phone or other mobile communication terminal 300 equipped with the camera module 50 illustrated in FIG. 1 will be described with reference to FIGS. 2, 3A, and 3B.

  The mobile communication terminal 300 is a smartphone-type mobile communication terminal or mobile terminal, and wireless communication for realizing various information communication between the imaging apparatus 100 having the camera module 50 and an external system or the like via the antenna 331. Part 330. In addition, although illustration is abbreviate | omitted, the portable communication terminal 300 also has a memory | storage part (ROM) which memorize | stores necessary data, such as a system program, various processing programs, and terminal ID besides the operation part containing a power switch etc. Prepare.

  In addition to the camera module 50 described above, the imaging apparatus 100 includes an optical system driving unit 101, an imaging interface (I / F) 102, an image processing circuit (ISP) 103, a temporary storage unit (RAM) 104, a data storage unit ( EEPROM) 105, CPU 106, display operation unit interface 107, auxiliary storage unit interface 108, display operation unit (LCD) 310, auxiliary storage unit (SD card, etc.) 320, and the like. Among these, the imaging interface 102, the image processing circuit 103, the temporary storage unit 104, the data storage unit 105, the CPU 106, the display operation unit interface 107, and the auxiliary storage unit interface 108 are the control unit 110 for driving the camera module 50 and the like. As a role. The control unit 110 also includes a communication unit interface 109. In addition, the image processing circuit 103, the temporary storage unit 104, the data storage unit 105, and the CPU 106 have a role as an image processing unit 111 that processes an image signal output from the camera module 50.

  The optical system driving unit 101 controls the state of the imaging lens 10 by operating the driving mechanism 55 a of the imaging lens 10 when performing focusing, exposure, and the like under the control of the CPU 106. The optical system driving unit 101 operates the driving mechanism 55a to appropriately move specific or all lenses in the imaging lens 10 along the optical axis AX, thereby causing the imaging lens 10 to perform a focusing operation.

  The imaging interface 102 is a part for passing the image signal output from the imaging element 51 to the control unit 110.

  The image processing circuit 103 performs image processing on the image signal output from the image sensor 51. In the image processing circuit 103, it is assumed that the image signal corresponds to a moving image, and the frame image constituting the image signal is processed. The image processing circuit 103 executes distortion correction processing on the image signal based on the lens correction data read from the data storage unit 105 in addition to normal image processing such as color correction, gradation correction, and zooming. .

  The temporary storage unit 104 is used as a work area for temporarily storing various processing programs executed by the control unit 110, data necessary for the execution, processing data, imaging data obtained by the imaging apparatus 100, and the like.

  The data storage unit 105 stores lens correction data used for image processing. Specifically, in addition to data for color correction, gradation correction, etc., parameters for distortion correction are stored.

  The CPU 106 comprehensively controls each unit and executes a program corresponding to each process. The CPU 106 can also perform various image processing such as color correction, gradation correction, and distortion correction on the image signal based on the lens correction data read from the data storage unit 105.

  The display operation unit interface 107 transfers the image signal output from the CPU 106 to the display operation unit 310 and transfers the operation signal from the display operation unit 310 to the CPU 106.

  The auxiliary storage unit interface 108 outputs the moving image and image data as a still image output from the CPU 106 to the auxiliary storage unit 320.

  The display operation unit 310 is a touch panel that displays data related to communication, captured images, and the like and receives user operations.

  The auxiliary storage unit 320 is detachable and is a part that records and stores the image signal processed by the image processing unit 111.

  Here, the photographing operation of the mobile communication terminal 300 including the imaging device 100 will be described. When the camera mode in which the mobile communication terminal 300 is operated as a camera is set, subject monitoring (through image display) and image shooting execution are performed. In monitoring, an image of a subject obtained through the imaging lens 10 is formed on the imaging surface I (see FIG. 1) of the imaging element 51. The image sensor 51 is scanned and driven by an image sensor drive unit (not shown), and outputs one frame of a digital signal obtained by digitizing a photoelectric conversion output corresponding to an optical image formed at a fixed period. The digital signal is input to the image processing circuit 103 and the temporary storage unit 104, and an image signal (video signal) processed by the image processing unit 111 is generated and output to the display operation unit 310 and the auxiliary storage unit 320. .

  The display operation unit 310 functions as a finder in monitoring and displays captured images in real time. In this state, focusing, exposure, and the like of the imaging lens 10 are set by driving the optical system driving unit 101 based on an operation input performed by the user via the display operation unit 310 at any time.

  In such a monitoring state, for example, still image data is captured when the user appropriately operates the display operation unit 310. One frame of image data (imaging data) stored in the temporary storage unit 104 is read and compressed in accordance with the operation content of the display operation unit 310. The compressed image data is recorded in the temporary storage unit 104 or the like via the control unit 110, for example.

  Hereinafter, image processing of the mobile communication terminal 300 will be described. In FIG. 2, the image signal output from the imaging lens 10 is input to the control unit 110 via the imaging interface 102. If the input image signal corresponds to a still image, the image signal is stored in the temporary storage unit 104, the CPU 106 reads the lens correction data from the data storage unit 105, and the image processing circuit 103 corrects the image signal. Various image processing is performed on the image signal based on the data. Here, the image processing includes image processing for displaying on the display operation unit 310 and image processing for storing in the auxiliary storage unit 320. On the other hand, when the input image signal corresponds to a moving image, the image signal is input to the image processing circuit 103, and the image processing circuit 103 converts the image signal into the image signal based on the lens correction data read from the correction data. Various image processing is performed on the image. The image signal subjected to the image processing is displayed on the display operation unit 310 via the display operation unit interface 107. The image signal subjected to image processing is also recorded in the auxiliary storage unit 320 via the auxiliary storage unit interface 108.

  The above-described imaging apparatus 100 is an example of an imaging apparatus suitable for the present invention, and the present invention is not limited to this.

  That is, the image pickup apparatus equipped with the camera module 50 or the image pickup lens 10 is not limited to the one built in the smartphone type mobile communication terminal 300, but is built into a mobile phone, a PHS (Personal Handyphone System), or the like. Alternatively, it may be incorporated in a PDA (Personal Digital Assistant), a tablet personal computer, a mobile personal computer, a digital still camera, a video camera, or the like.

Hereinafter, returning to FIG. 1, the imaging lens 10 according to an embodiment of the present invention will be described in detail. The imaging lens 10 shown in FIG. 1 forms a subject image on an imaging surface (projected surface) I of an image sensor 51. The imaging lens 10 has a positive refractive power in order from the object side and is near the optical axis AX. A first lens L1 having a meniscus shape with a convex surface facing the object side, a second lens L2 having a negative refractive power and a concave surface facing the object side in the vicinity of the optical axis AX, and a third lens L2. The lens L3, a fourth lens L4 having a positive refractive power, and a fifth lens L5 having a negative refractive power and having a biconcave shape in the vicinity of the optical axis AX. Here, the image side surface S22 of the second lens L2 has a shape having a diverging action at the peripheral portion, and the light beam incident on the image side surface S22 of the second lens L2 passes through the image side surface S22 of the second lens L2. The light is emitted in a direction away from the optical axis AX. Further, the sag amount h31 of the object side surface S31 of the third lens L3 is a negative value in the peripheral portion. The image side surface S52 of the fifth lens L5 has an aspherical shape and has an extreme value at a position P other than the intersection with the optical axis AX (see FIG. 1). The aperture stop S is disposed on the object side surface S11 side of the first lens L1, but may be disposed between the image side surface S12 of the first lens L1 and the object side surface S21 of the second lens L2.
The imaging lens 10 satisfies the conditional expressions (1) and (2) already described.
0.55 <f1 / f <0.95 (1)
0.35 <d14 / EPD <0.55 (2)
Here, f1 is the focal length of the first lens L1, f is the focal length of the entire imaging lens 10, and d14 is the optical axis from the object side surface S11 of the first lens L1 to the image side surface S22 of the second lens L2. The distance on AX, and EPD is the diameter of the entrance pupil of the entire imaging lens 10 system.

  The imaging lens 10 according to the embodiment includes a so-called telephoto type configuration in which a positive lens group including first to fourth lenses L1 to L4 is disposed, and a negative fifth lens L5 is disposed on the image side of the positive lens group. It has become. The telephoto type lens configuration is advantageous for downsizing the entire length of the imaging lens 10.

  Further, in the imaging lens 10, by using two or more negative lenses among the five-lens configuration, the number of surfaces having a diverging action can be increased to easily correct the Petzval sum, and good imaging performance up to the periphery of the screen Can be secured. In addition, the object side surface S11 of the first lens L1 is a convex surface, and the object side surface S11 has a stronger curvature than the image side surface S12, so that the combined principal point position of the entire imaging lens 10 system is closer to the object side. This is advantageous in reducing the overall length of the imaging lens 10. Furthermore, the shape of the object side surface S21 of the second lens L2 is concentric with respect to the aperture stop S by making the second lens L2 a meniscus shape or concave shape with the concave surface facing the object side in the vicinity of the optical axis AX. Therefore, various off-axis aberrations generated on the object side surface S21 of the second lens L2 can be suppressed. By making the image side surface S22 of the second lens L2 have a diverging action at the peripheral portion, it is possible to satisfactorily correct field curvature, distortion, lateral chromatic aberration, and the like with respect to the ambient light. Here, the “shape having a diverging action” is a surface on which the light incident on the image side surface S22 of the second lens L2 exits in a direction away from the optical axis AX after passing through the image side surface S22 of the second lens L2. That means. By setting the sag amount h31 of the object side surface S31 of the third lens L3 to a negative value at the periphery, the shape of the object side surface S31 of the third lens L3 with respect to the aperture stop S is the same as that of the second lens L2. Therefore, the off-axis aberrations generated on the object side surface S31 of the third lens L3 can be suppressed. Here, the fact that the sag amount takes a negative value at a certain height h means that the displacement amount of the surface at the height h is located closer to the object side than the point on the optical axis AX. Yes. By setting the image side surface S52 of the fifth lens L5 arranged closest to the image side to be an aspherical surface, various aberrations at the periphery of the screen can be corrected satisfactorily. Furthermore, by making the fifth lens L5 an aspherical shape having an extreme value at a position P other than the intersection with the optical axis AX, the telecentric characteristics of the image-side light beam can be easily secured. “Extreme value” is a line on an aspheric surface where the tangent plane or tangent of the apex of the aspheric surface is a plane or line segment perpendicular to the optical axis AX when considering a lens cross-sectional shape curve within the effective radius. Or it is a point.

  In the imaging lens 10, the third lens L3 can have, for example, a negative refractive power and a concave surface facing the image side in the vicinity of the optical axis AX, but can also have a positive refractive power. it can. The sag amount h32 of the image side surface S32 of the third lens L3 has a negative value at the peripheral portion.

In the imaging lens 10, the conditional expression (1) is a conditional expression for appropriately setting the focal length of the first lens L <b> 1 and appropriately shortening the entire length of the imaging lens 10 and correcting the aberration.
When the value f1 / f of conditional expression (1) is below the upper limit, the refractive power of the first lens L1 can be maintained moderately, and the composite principal point from the first lens L1 to the fourth lens L4 can be more object-oriented. It can arrange | position to the side and can shorten the imaging lens 10 full length. On the other hand, when the value f1 / f of the conditional expression (1) exceeds the lower limit, the refractive power of the first lens L1 does not increase more than necessary, and higher-order spherical aberration and coma generated in the first lens L1. Aberration can be suppressed small.
The value f1 / f is more preferably within the range of the following conditional expression (1) ′.
0.60 <f1 / f <0.90 (1) ′

In the imaging lens 10, the conditional expression (2) is a conditional expression for appropriately setting the distance on the optical axis AX from the object side surface S11 of the first lens L1 to the image side surface S22 of the second lens L2.
When the conditional expression (2) is satisfied, the second lens L2 can be disposed at an optimum position, and both the downsizing of the entire length of the imaging lens 10 and good aberration correction can be achieved. Specifically, since the value d14 / EPD of conditional expression (2) is below the upper limit, the image side surface S22 of the second lens L2 having a diverging action can be disposed more on the object side, and thus aberrations Correction can be performed satisfactorily. Moreover, since the total value of the thickness of the 1st lens L1 and the thickness of the 2nd lens L2 can be made small, it becomes possible to shorten the imaging lens 10 full length as a result. On the other hand, when the value d14 / EPD of conditional expression (2) exceeds the lower limit, the second lens L2 does not go too far toward the object side, and the thickness of the peripheral portion of the first lens L1 and the center thickness of the second lens L2 are prevented. Does not become too thin and does not impair the moldability.
The value d14 / EPD is more preferably within the range of the following conditional expression (2) ′.
0.40 <d14 / EPD <0.53 (2) ′

In the imaging lens 10 of the embodiment, in addition to the conditional expressions (1) and (2), the conditional expression (3) already described.
0.30 <r1 / f <0.50 (3)
Satisfied. Here, r1 is the radius of curvature of the object side surface S11 of the first lens L1.
The imaging lens 10 of the embodiment more preferably satisfies the following conditional expression (3) ′.
0.35 <r1 / f <0.45 (3) ′

In the imaging lens 10 of the embodiment, in addition to the conditional expressions (1) and (2), the conditional expression (4) already described.
−1.20 <f / f23 <−0.15 (4)
Satisfied. Here, f23 is a combined focal length of the second lens L2 and the third lens L3.
More preferably, the imaging lens 10 of the embodiment satisfies the following conditional expression (4) ′.
−1.10 <f / f23 <−0.20 (4) ′

In the imaging lens 10 of the embodiment, in addition to the conditional expressions (1) and (2), the conditional expression (5) already described.
−2.0 <(r3 + r4) / (r3−r4) ≦ −1.0 (5)
Satisfied. Here, r3 is the radius of curvature of the object side surface S21 of the second lens L2, and r4 is the radius of curvature of the image side surface S22 of the second lens L2.
The imaging lens 10 of the embodiment preferably satisfies the following conditional expression (5) ′.
−1.8 <(r3 + r4) / (r3−r4) ≦ −1.0 (5) ′

In the imaging lens 10 of the embodiment, in addition to the conditional expressions (1) and (2), the conditional expression (6) already described.
0.0 <| f2 / f3 | <1.00 (6)
Satisfied. Here, f2 is the focal length of the second lens L2, and f3 is the focal length of the third lens L3.
More preferably, the imaging lens 10 of the embodiment satisfies the following conditional expression (6) ′.
0.0 <| f2 / f3 | <0.90 (6) ′

In the imaging lens 10 of the embodiment, in addition to the conditional expressions (1) and (2), the conditional expression (7) already described.
15 <ν3 <45 (7)
Satisfied. Where ν3 is the Abbe number of the third lens L3.
The imaging lens 10 of the embodiment preferably satisfies the following conditional expression (7) ′.
20 <ν3 <28 (7) ′

In the imaging lens 10 of the embodiment, in addition to the conditional expressions (1) and (2), the conditional expression (8) already described.
20 <ν1-ν2 <70 (8)
Satisfied. Here, ν1 is the Abbe number of the first lens L1, and ν2 is the Abbe number of the second lens L2.
The imaging lens 10 of the embodiment preferably satisfies the following conditional expression (8) ′.
25 <ν1-ν2 <65 (8) ′

In the imaging lens 10 of the embodiment, in addition to the conditional expressions (1) and (2), the conditional expression (9) already described.
f / EPD <1.95 (9)
Satisfied.
The imaging lens 10 of the embodiment more preferably satisfies the following conditional expression (9) ′.
f / EPD <1.90 (9) ′

  Note that the imaging lens 10 of the embodiment may further include a lens having substantially no power.

ただし、
Ａｉ：ｉ次の非球面係数
Ｒ ：曲率半径
Ｋ ：円錐定数〔Example〕
Examples of the imaging lens of the present invention will be shown below. Symbols used in each example are as follows.
f: Focal length of the entire imaging lens system fB: Back focus F: F value 2Y: Diagonal length of the imaging surface of the imaging device ENTP: Entrance pupil position (distance from the first surface to the entrance pupil position)
EXTP: exit pupil position (distance from imaging surface to exit pupil position)
H1: Front principal point position (distance from first surface to front principal point position)
H2: Rear principal point position (distance from the final surface to the rear principal point position)
R: radius of curvature D: axial distance Nd: refractive index νd of lens material with respect to d-line: Abbe number of lens material In each example, the surface described with “*” after each surface number has an aspherical shape. The shape of the aspherical surface is expressed by the following “Equation 1” with the vertex of the surface as the origin, the X axis in the direction of the optical axis AX, and the height in the direction perpendicular to the optical axis AX as h.

However,
Ai: i-order aspheric coefficient R: radius of curvature K: conic constant

Example 1
The overall specifications of the imaging lens of Example 1 are shown below.
f = 2.89mm
fB = 0.32mm
F = 2.06
2Y = 4.59mm
ENTP = 0mm
EXTP = -1.79mm
H1 = −1.07mm
H2 = −2.57mm

The lens surface data of Example 1 is shown in Table 1 below.
[Table 1]
Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (STOP) infinity -0.149 0.70
2 * 1.101 0.403 1.54470 56.2 0.71
3 * 10.210 0.073 0.70
4 * -3.441 0.150 1.63470 23.9 0.71
5 * -14.179 0.353 0.68
6 * -6.386 0.288 1.63470 23.9 0.73
7 * 42.390 0.312 0.89
8 * -14.752 0.524 1.54470 56.2 1.10
9 * -0.698 0.228 1.31
10 * -1.129 0.274 1.54470 56.2 1.84
11 * 1.515 0.400 1.99
12 infinity 0.110 1.51630 64.1 2.50
13 infinity 2.50

The aspheric coefficients of the lens surfaces of Example 1 are shown in Table 2 below. In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is expressed using E (for example, 2.5E-02).
[Table 2]
Second side
K = -0.48483E-01, A4 = 0.98924E-02, A6 = -0.52022E-02, A8 = -0.18584E + 00,
A10 = 0.11409E + 00, A12 = -0.65825E-01, A14 = -0.23705E + 01
Third side
K = -0.47523E + 02, A4 = -0.50658E-01, A6 = -0.15304E + 00, A8 = -0.12094E + 00,
A10 = -0.41308E-01, A12 = -0.15534E + 00, A14 = -0.30333E + 00
4th page
K = -0.25137E + 02, A4 = 0.12763E + 00, A6 = 0.14995E + 00, A8 = 0.46857E-01,
A10 = 0.17206E + 00, A12 = 0.35139E + 00, A14 = 0.24471E + 00
5th page
K = 0.00000E + 00, A4 = 0.26330E + 00, A6 = 0.28020E + 00, A8 = 0.17425E + 00,
A10 = 0.53613E + 00, A12 = 0.25343E + 00, A14 = -0.44662E-01
6th page
K = 0.70657E + 02, A4 = -0.36299E + 00, A6 = -0.82891E-01, A8 = 0.67962E-01,
A10 = 0.54456E + 00, A12 = 0.11486E + 01, A14 = -0.14056E + 01
7th page
K = 0.80000E + 02, A4 = -0.33913E + 00, A6 = 0.28248E-01, A8 = -0.46489E-01,
A10 = 0.24981E + 00, A12 = 0.20636E + 00, A14 = -0.15600E + 00
8th page
K = -0.79304E + 02, A4 = -0.96407E-01, A6 = 0.34324E-01, A8 = -0.59747E-01,
A10 = 0.24938E-01, A12 = 0.64671E-01, A14 = -0.69407E-01
9th page
K = -0.37337E + 01, A4 = -0.15808E + 00, A6 = 0.25532E + 00, A8 = -0.47352E-01,
A10 = -0.41763E-01, A12 = -0.40061E-02, A14 = 0.60407E-02
10th page
K = -0.88598E + 01, A4 = -0.44100E-01, A6 = 0.12997E-01, A8 = 0.27719E-02,
A10 = -0.27668E-03, A12 = -0.22061E-03, A14 = 0.33506E-04
11th page
K = -0.20227E + 02, A4 = -0.56264E-01, A6 = 0.68316E-02, A8 = -0.20519E-02,
A10 = 0.67564E-05, A12 = -0.75606E-04, A14 = 0.32868E-04

The single lens data of Example 1 is shown in Table 3 below.
[Table 3]
Lens Start surface Focal length (mm)
1 2 2.230
2 4 -7.198
3 6 -8.725
4 8 1.329
5 10 -1.146

  FIG. 4 is a cross-sectional view of the imaging lens 11 and the like of the first embodiment. The imaging lens 11 has, in order from the object side, a first lens L1 having a positive refractive power near the optical axis AX and a meniscus shape with a convex surface facing the object side, and a negative refractive power near the optical axis AX. The second lens L2 having a meniscus shape with the concave surface facing the object side, the third lens L3 having a negative refractive power in the vicinity of the optical axis AX, and the positive refractive power in the vicinity of the optical axis AX. And a fourth lens L4 having a meniscus shape with a convex surface facing the image side, and a biconcave fifth lens L5 having negative refractive power in the vicinity of the optical axis AX. All the lenses L1 to L5 are made of a plastic material. An aperture stop S is disposed on the object side surface S11 side of the first lens L1. Between the light exit surface of the fifth lens L5 and the imaging surface (image surface) I, a parallel plate F having an appropriate thickness is disposed. The parallel plate F is assumed to be an optical low-pass filter, an IR cut filter, a seal glass of a solid-state image sensor, and the like (the same applies to the following examples).

  5A to 5C show the spherical aberration, astigmatism, and distortion of the imaging lens 11 of Example 1, and FIGS. 5D and 5E show the meridional coma aberration of the imaging lens 11. FIG.

(Example 2)
The overall specifications of the imaging lens of Example 2 are shown below.
f = 3.86mm
fB = 0.18mm
F = 1.85
2Y = 5.842mm
ENTP = 0mm
EXTP = -2.26mm
H1 = -2.25mm
H2 = -3.68mm

The lens surface data of Example 2 is shown in Table 4 below.
[Table 4]
Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (STOP) infinity -0.335 1.04
2 * 1.459 0.651 1.54470 56.2 1.04
3 * -13.183 0.076 1.00
4 * -2.620 0.180 1.63470 23.9 0.99
5 * -100.000 0.441 0.93
6 * -272.942 0.347 1.63470 23.9 0.98
7 * 45.830 0.567 1.15
8 * -31.624 0.497 1.54470 56.2 1.57
9 * -1.584 0.530 1.74
10 * -6.632 0.303 1.54470 56.2 2.26
11 * 1.529 0.500 2.48
12 infinity 0.210 1.51630 64.1 2.90
13 infinity 2.95

The aspherical coefficient of the lens surface of Example 2 is shown in Table 5 below.
[Table 5]
Second side
K = -0.76883E-01, A3 = 0.00000E + 00, A4 = 0.66635E-02, A5 = 0.00000E + 00,
A6 = 0.10611E-01, A8 = -0.26326E-01, A10 = 0.11659E-01,
A12 = 0.27967E-01, A14 = -0.36646E-01
Third side
K = -0.80694E + 02, A3 = 0.00000E + 00, A4 = 0.37694E-01, A5 = 0.00000E + 00,
A6 = -0.12840E-01, A8 = 0.25887E-02, A10 = -0.21262E-01,
A12 = 0.14366E-01, A14 = -0.10563E-01
4th page
K = -0.31264E + 02, A3 = 0.00000E + 00, A4 = 0.10790E + 00, A5 = 0.00000E + 00,
A6 = -0.11183E-01, A8 = -0.26803E-01, A10 = 0.33822E-01,
A12 = 0.24551E-01, A14 = -0.96675E-02
5th page
K = 0.90000E + 02, A3 = -0.41969E-01, A4 = 0.39867E + 00, A5 = -0.18839E + 00,
A6 = -0.12700E + 00, A8 = 0.22138E + 00, A10 = 0.22239E-01,
A12 = -0.21339E + 00, A14 = 0.20636E + 00
6th page
K = 0.90000E + 02, A3 = -0.36470E-01, A4 = -0.27978E-01, A5 = -0.26463E + 00,
A6 = 0.15619E + 00, A8 = 0.66328E-02, A10 = -0.11302E + 00,
A12 = 0.13646E + 00, A14 = -0.20200E-01
7th page
K = 0.90000E + 02, A3 = 0.36513E-01, A4 = -0.22996E + 00, A5 = 0.10171E + 00,
A6 = -0.45782E-01, A8 = -0.14196E-01, A10 = 0.29221E-01,
A12 = -0.15934E-02, A14 = 0.45445E-02
8th page
K = -0.90000E + 02, A3 = -0.37255E-01, A4 = 0.12886E + 00, A5 = -0.10117E + 00,
A6 = 0.34840E-02, A8 = 0.25365E-02, A10 = -0.10502E-01,
A12 = 0.58437E-02, A14 = -0.86837E-03
9th page
K = -0.39637E + 01, A3 = -0.40867E-02, A4 = 0.14766E-01, A5 = 0.14637E-01,
A6 = 0.63526E-02, A8 = -0.23576E-01, A10 = 0.31697E-02,
A12 = 0.27100E-02, A14 = -0.65083E-03
10th page
K = 0.51413E + 01, A3 = -0.13876E + 00, A4 = -0.31043E-01, A5 = 0.19406E-01,
A6 = 0.14894E-01, A8 = -0.14689E-03, A10 = -0.27782E-03,
A12 = -0.23549E-04, A14 = 0.58801E-05
11th page
K = -0.65794E + 01, A3 = -0.15524E + 00, A4 = 0.29088E-01, A5 = 0.31989E-02,
A6 = 0.12195E-02, A8 = -0.92919E-03, A10 = 0.65865E-04,
A12 = -0.10294E-04, A14 = 0.17486E-05

The single lens data of Example 2 is shown in Table 6 below.
[Table 6]
Lens Start surface Focal length (mm)
1 2 2.450
2 4 -4.243
3 6 -61.801
4 8 3.044
5 10 -2.251

  FIG. 6 is a cross-sectional view of the imaging lens 12 and the like of the second embodiment. In order from the object side, the imaging lens 12 has a biconvex first lens L1 having a positive refractive power in the vicinity of the optical axis AX, and a negative refractive power in the vicinity of the optical axis AX and having a concave surface directed toward the object side. A second lens L2 having a meniscus shape, a third lens L3 having negative refractive power in the vicinity of the optical axis AX, and a biconcave third lens L3 having positive refractive power in the vicinity of the optical axis AX and having a convex surface directed toward the image side A fourth lens L4 having a meniscus shape and a biconcave fifth lens L5 having negative refractive power in the vicinity of the optical axis AX are provided. All the lenses L1 to L5 are made of a plastic material. An aperture stop S is disposed on the object side surface S11 side of the first lens L1. Between the light exit surface of the fifth lens L5 and the imaging surface (image surface) I, a parallel plate F having an appropriate thickness is disposed.

  7A to 7C show spherical aberration, astigmatism, and distortion of the imaging lens 12 of Example 2, and FIGS. 7D and 7E show meridional coma aberration of the imaging lens 12. FIG.

(Example 3)
The overall specifications of the imaging lens of Example 3 are shown below.
f = 2.9mm
fB = 0.36mm
F = 2.09
2Y = 4.59mm
ENTP = 0mm
EXTP = -1.82mm
H1 = −0.94mm
H2 = −2.53mm

The lens surface data of Example 3 is shown in Table 7 below.
[Table 7]
Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (STOP) infinity -0.166 0.69
2 * 1.168 0.417 1.54470 56.2 0.72
3 * 6.501 0.136 0.73
4 * -3.270 0.150 1.63470 23.9 0.72
5 * -100.393 0.229 0.73
6 * 3.949 0.205 1.63470 23.9 0.80
7 * 4.200 0.393 0.87
8 * -4.503 0.434 1.54470 56.2 1.03
9 * -0.927 0.356 1.18
10 * -13.244 0.261 1.54470 56.2 1.83
11 * 1.101 0.400 1.97
12 infinity 0.110 1.51630 64.1 2.24
13 infinity 2.27

The aspherical coefficients of the lens surfaces of Example 3 are shown in Table 8 below.
[Table 8]
Second side
K = 0.66961E-01, A3 = 0.00000E + 00, A4 = 0.10954E-01, A5 = 0.00000E + 00,
A6 = 0.58563E-02, A8 = -0.35087E-01, A10 = 0.16890E + 00,
A12 = 0.19833E + 00, A14 = -0.11557E + 01
Third side
K = -0.15056E + 02, A3 = 0.00000E + 00, A4 = -0.31116E-01, A5 = 0.00000E + 00,
A6 = 0.13326E + 00, A8 = -0.11946E + 00, A10 = -0.85901E + 00,
A12 = -0.73833E + 00, A14 = 0.14988E + 01
4th page
K = -0.54737E + 02, A3 = 0.00000E + 00, A4 = 0.41517E-02, A5 = 0.00000E + 00,
A6 = 0.49357E + 00, A8 = -0.66970E + 00, A10 = -0.13216E + 01,
A12 = -0.13813E + 00, A14 = 0.31515E + 01
5th page
K = 0.79919E + 02, A3 = -0.32634E-01, A4 = 0.26173E + 00, A5 = 0.55406E-01,
A6 = 0.16659E + 00, A8 = -0.19977E + 00, A10 = -0.13080E + 00,
A12 = -0.69580E + 00, A14 = 0.22189E + 01
6th page
K = -0.79983E + 02, A3 = 0.46336E-02, A4 = -0.26565E + 00, A5 = -0.12762E + 00,
A6 = 0.21391E + 00, A8 = -0.19174E + 00, A10 = 0.77515E-01,
A12 = 0.12836E + 01, A14 = -0.11258E + 01
7th page
K = -0.55215E + 02, A3 = 0.18737E-01, A4 = -0.30716E + 00, A5 = 0.71382E-01,
A6 = -0.32112E-01, A8 = -0.66783E-01, A10 = 0.15135E + 00,
A12 = -0.75625E-02, A14 = 0.24010E + 00
8th page
K = 0.11675E + 02, A3 = -0.16577E + 00, A4 = 0.44224E + 00, A5 = -0.52861E + 00,
A6 = 0.47563E-01, A8 = 0.27513E + 00, A10 = -0.19435E + 00,
A12 = -0.16870E + 00, A14 = 0.17171E + 00
9th page
K = -0.62973E + 01, A3 = -0.22920E + 00, A4 = -0.35573E-01, A5 = 0.60127E-01,
A6 = 0.94451E-01, A8 = -0.90933E-01, A10 = 0.32607E-01,
A12 = 0.31949E-01, A14 = -0.20835E-01
10th page
K = 0.55399E + 01, A3 = -0.18807E + 00, A4 = -0.92684E-02, A5 = 0.23411E-01,
A6 = 0.30107E-01, A8 = -0.22395E-02, A10 = -0.13408E-02,
A12 = 0.17200E-03, A14 = 0.67538E-05
11th page
K = -0.99210E + 01, A3 = -0.78228E-01, A4 = -0.32880E-01, A5 = 0.39632E-02,
A6 = 0.12812E-01, A8 = -0.49206E-02, A10 = 0.87731E-03,
A12 = -0.22492E-03, A14 = 0.42813E-04

The single lens data of Example 3 is shown in Table 9 below.
[Table 9]
Lens Start surface Focal length (mm)
1 2 2.543
2 4 -5.329
3 6 79.197
4 8 2.056
5 10 -1.855

  FIG. 8 is a cross-sectional view of the imaging lens 13 and the like of the third embodiment. The imaging lens 13 has, in order from the object side, a first lens L1 having a positive refractive power near the optical axis AX and a meniscus shape with a convex surface facing the object side, and a negative refractive power near the optical axis AX. A second lens L2 having a meniscus shape with a concave surface facing the object side, a third lens L3 having a positive refractive power near the optical axis AX and a meniscus shape having a convex surface facing the object side, and an optical axis AX A fourth lens L4 having a meniscus shape having a positive refractive power in the vicinity and a convex surface facing the image side, and a biconcave fifth lens L5 having a negative refractive power in the vicinity of the optical axis AX are provided. All the lenses L1 to L5 are made of a plastic material. An aperture stop S is disposed on the object side surface S11 side of the first lens L1. Between the light exit surface of the fifth lens L5 and the imaging surface (image surface) I, a parallel plate F having an appropriate thickness is disposed.

  9A to 9C show the spherical aberration, astigmatism, and distortion of the imaging lens 13 of Example 3, and FIGS. 9D and 9E show the meridional coma aberration of the imaging lens 13.

Example 4
The overall specifications of the imaging lens of Example 4 are shown below.
f = 3.77 mm
fB = 0.37mm
F = 1.85
2Y = 5.842mm
ENTP = 0mm
EXTP = −2.07mm
H1 = −2.06mm
H2 = -3.4mm

The lens surface data of Example 4 is shown in Table 10 below.
[Table 10]
Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (STOP) infinity -0.303 1.02
2 * 1.577 0.527 1.54470 56.2 1.02
3 * 18.055 0.222 0.97
4 * -2.176 0.170 1.63470 23.9 0.97
5 * -89.286 0.234 0.98
6 * 2.603 0.433 1.56400 42.3 1.07
7 * 45.732 0.839 1.18
8 * -5.824 0.423 1.54470 56.2 1.40
9 * -1.456 0.439 1.60
10 * -7.289 0.314 1.54470 56.2 1.90
11 * 1.415 0.300 2.30
12 infinity 0.210 1.51630 64.1 2.77
13 infinity 2.85

The aspherical coefficients of the lens surfaces of Example 4 are shown in Table 11 below.
[Table 11]
Second side
K = 0.46468E + 00, A4 = -0.91731E-02, A6 = -0.49393E-02, A8 = 0.10562E-01,
A10 = -0.60934E-01, A12 = 0.82997E-01, A14 = -0.39102E-01
Third side
K = 0.82150E + 02, A3 = 0.00000E + 00, A4 = 0.64406E-02, A5 = 0.00000E + 00,
A6 = 0.26342E-01, A7 = 0.00000E + 00, A8 = -0.49634E-01,
A10 = 0.32927E-01, A12 = 0.17762E-01, A14 = -0.26158E-01
4th page
K = -0.28380E + 02, A4 = 0.15492E-01, A6 = 0.15080E + 00, A8 = -0.16476E + 00,
A10 = -0.52075E-02, A12 = 0.12356E + 00, A14 = -0.67260E-01
5th page
K = -0.90000E + 02, A3 = 0.00000E + 00, A4 = 0.20122E + 00, A5 = 0.00000E + 00,
A6 = -0.78206E-01, A7 = 0.00000E + 00, A8 = 0.34650E-01,
A10 = 0.36034E-01, A12 = -0.29095E-01, A14 = 0.95758E-02
6th page
K = -0.24033E + 01, A3 = -0.58729E-01, A4 = 0.44848E-01, A5 = -0.19547E + 00,
A6 = 0.51629E-01, A7 = 0.11573E + 00, A8 = -0.46509E-01,
A10 = -0.70413E-01, A12 = 0.36357E-01, A14 = -0.39707E-02
7th page
K = 0.56316E + 02, A4 = -0.66758E-01, A6 = -0.81900E-02, A8 = -0.39453E-01,
A10 = 0.19362E-01, A12 = -0.19777E-02, A14 = -0.39508E-02
8th page
K = -0.90000E + 02, A3 = -0.45317E-02, A4 = -0.18989E-01, A5 = -0.45958E-01,
A6 = 0.96459E-02, A7 = 0.10805E-01, A8 = 0.28323E-03,
A10 = -0.92876E-02, A12 = 0.10949E-02, A14 = -0.27849E-03
9th page
K = -0.57602E + 01, A4 = -0.82558E-01, A6 = 0.42777E-01, A8 = -0.14428E-01,
A10 = 0.41889E-02, A12 = -0.75672E-03, A14 = 0.69404E-04
10th page
K = 0.56942E + 01, A3 = -0.21160E + 00, A4 = -0.34771E-02, A5 = 0.27677E-01,
A6 = 0.61406E-02, A7 = 0.17122E-02, A8 = 0.26823E-03,
A10 = -0.15410E-03, A12 = -0.33556E-04, A14 = 0.13752E-05
11th page
K = -0.76965E + 01, A3 = -0.20855E + 00, A4 = 0.11033E + 00, A5 = -0.34109E-01,
A6 = 0.11153E-02, A7 = 0.20717E-02, A8 = -0.34787E-03,
A10 = -0.26423E-04, A12 = -0.26193E-04, A14 = 0.48515E-05

The single lens data of Example 4 is shown in Table 12 below.
[Table 12]
Lens Start surface Focal length (mm)
1 2 3.137
2 4 -3.517
3 6 4.876
4 8 3.446
5 10 -2.148

  FIG. 10 is a cross-sectional view of the imaging lens 14 and the like of the fourth embodiment. The imaging lens 14 has, in order from the object side, a first lens L1 having a positive refractive power near the optical axis AX and a meniscus shape with a convex surface facing the object side, and a negative refractive power near the optical axis AX. A second lens L2 having a meniscus shape with a concave surface facing the object side, a third lens L3 having a positive refractive power near the optical axis AX and a meniscus shape having a convex surface facing the object side, and an optical axis AX A fourth lens L4 having a meniscus shape having a positive refractive power in the vicinity and a convex surface facing the image side, and a biconcave fifth lens L5 having a negative refractive power in the vicinity of the optical axis AX are provided. All the lenses L1 to L5 are made of a plastic material. An aperture stop S is disposed on the object side surface S11 side of the first lens L1. Between the light exit surface of the fifth lens L5 and the imaging surface (image surface) I, a parallel plate F having an appropriate thickness is disposed.

  11A to 11C show spherical aberration, astigmatism, and distortion of the imaging lens 14 of Example 4, and FIGS. 11D and 11E show meridional coma aberration of the imaging lens 14. FIG.

(Example 5)
f = 3.77 mm
fB = 0.42mm
F = 1.92
2Y = 5.842mm
ENTP = 0.45mm
EXTP = -1.99mm
H1 = -1.68mm
H2 = -3.36mm

The lens surface data of Example 5 is shown in Table 13 below.
[Table 13]
Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 infinity 0.000 1.31
2 * 1.549 0.528 1.54470 56.2 1.09
3 * -60.971 0.050 1.08
4 (STOP) infinity 0.115 0.93
5 * -2.398 0.170 1.63470 23.9 0.93
6 * -89.286 0.356 0.92
7 * 3.717 0.329 1.56930 39.7 1.00
8 * 13.014 0.842 1.12
9 * -9.889 0.514 1.54470 56.2 1.45
10 * -1.270 0.329 1.63
11 * -10.498 0.323 1.54470 56.2 2.00
12 * 1.119 0.300 2.43
13 infinity 0.210 1.51630 64.1 3.50
14 infinity 3.50

The aspheric coefficients of the lens surfaces of Example 5 are shown in Table 14 below.
[Table 14]
Second side
K = 0.33110E + 00, A4 = -0.28123E-02, A6 = -0.49633E-01, A8 = 0.55545E-01,
A10 = -0.73641E-01, A12 = 0.36765E-01, A14 = -0.33288E-01
Third side
K = -0.90000E + 02, A3 = 0.00000E + 00, A4 = -0.67073E-02, A5 = 0.00000E + 00,
A6 = 0.20870E-01, A7 = 0.00000E + 00, A8 = -0.51339E-01,
A10 = 0.42987E-02, A12 = 0.66808E-02, A14 = -0.98075E-02
5th page
K = -0.27226E + 02, A4 = 0.75642E-01, A6 = 0.11248E + 00, A8 = -0.17677E + 00,
A10 = 0.29284E-01, A12 = 0.15304E + 00, A14 = -0.79221E-01
6th page
K = -0.90000E + 02, A3 = 0.00000E + 00, A4 = 0.25655E + 00, A5 = 0.00000E + 00,
A6 = -0.10093E + 00, A7 = 0.00000E + 00, A8 = 0.26615E-01,
A10 = 0.58773E-01, A12 = -0.14693E-01, A14 = 0.95758E-02
7th page
K = -0.55174E + 01, A3 = -0.46809E-01, A4 = 0.25656E-01, A5 = -0.23349E + 00,
A6 = 0.44535E-01, A7 = 0.10892E + 00, A8 = -0.60568E-01,
A10 = -0.71925E-01, A12 = 0.41878E-01, A14 = -0.31659E-01
8th page
K = -0.90000E + 02, A4 = -0.10931E + 00, A6 = -0.19868E-01, A8 = -0.39580E-01,
A10 = 0.18804E-01, A12 = -0.32039E-02, A14 = -0.87524E-02
9th page
K = -0.90000E + 02, A3 = -0.29306E-01, A4 = 0.60053E-01, A5 = -0.10116E + 00,
A6 = 0.71803E-02, A7 = 0.17850E-01, A8 = 0.28277E-02,
A10 = -0.10474E-01, A12 = 0.20016E-02, A14 = -0.99254E-04
10th page
K = -0.42828E + 01, A4 = -0.65396E-01, A6 = 0.20767E-01, A8 = -0.12419E-01,
A10 = 0.60913E-02, A12 = -0.76769E-03, A14 = -0.30396E-04
11th page
K = 0.10065E + 02, A3 = -0.21749E + 00, A4 = -0.15574E-01, A5 = 0.32147E-01,
A6 = 0.84838E-02, A7 = 0.26237E-02, A8 = -0.74121E-04,
A10 = -0.31431E-03, A12 = -0.80630E-04, A14 = 0.13770E-04
12th page
K = -0.44201E + 01, A3 = -0.28551E + 00, A4 = 0.15540E + 00, A5 = -0.31162E-01,
A6 = -0.27078E-02, A7 = 0.41252E-03, A8 = -0.15457E-03,
A10 = 0.80807E-04, A12 = -0.12932E-04, A14 = 0.13931E-05

The single lens data of Example 5 is shown in Table 15 below.
[Table 15]
Lens Start surface Focal length (mm)
1 2 2.782
2 5 -3.886
3 7 9.024
4 9 2.621
5 11 -1.839

  FIG. 12 is a cross-sectional view of the imaging lens 15 and the like according to the fifth embodiment. The imaging lens 15 has, in order from the object side, a biconvex first lens L1 having a positive refractive power in the vicinity of the optical axis AX, and a negative refractive power in the vicinity of the optical axis AX and having a concave surface directed toward the object side. A second lens L2 having a meniscus shape, a third lens L3 having a meniscus shape having a positive refractive power near the optical axis AX and a convex surface facing the object side, and a positive refractive power near the optical axis AX. And a fourth lens L4 having a meniscus shape with a convex surface facing the image side, and a biconcave fifth lens L5 having negative refractive power in the vicinity of the optical axis AX. All the lenses L1 to L5 are made of a plastic material. An aperture stop S is disposed between the image side surface S12 of the first lens L1 and the object side surface S21 of the second lens L2. Between the light exit surface of the fifth lens L5 and the imaging surface (image surface) I, a parallel plate F having an appropriate thickness is disposed.

  13A to 13C show spherical aberration, astigmatism, and distortion of the imaging lens 15 of Example 5, and FIGS. 13D and 13E show meridional coma aberration of the imaging lens 15. FIG.

For reference, Table 16 below summarizes the values of Examples 1 to 5 corresponding to the conditional expressions (1) to (10).
[Table 16]

  As mentioned above, although this invention was demonstrated according to embodiment and an Example, this invention is not limited to the said embodiment etc.

  In recent years, as a method for mounting an image pickup apparatus at a low cost and in large quantities, a reflow process (heating process) is performed on a substrate on which a solder has been potted in advance, with an IC chip and other electronic components and optical elements placed on the board. A technique has been proposed in which an electronic component and an optical element are simultaneously mounted on a substrate by melting the substrate. In order to perform mounting using such a reflow process, it is necessary to heat the optical element to about 200 to 260 ° C. together with the electronic components. At such a high temperature, the lens using the thermoplastic resin is heated. There is a problem that the optical performance deteriorates due to deformation or discoloration. As one of the methods for solving such problems, a technology that uses a glass mold lens having excellent heat resistance performance and achieves both miniaturization and optical performance in a high temperature environment has been proposed. Generally, the cost is higher than the lens using the lens. For this reason, there has been a problem that it is impossible to meet the demand for cost reduction of the imaging apparatus. Therefore, when an energy curable resin is used as the material of the imaging lenses 11 to 15 of Examples 1 to 5, when the lens is exposed to a higher temperature than a lens using a thermoplastic resin such as polycarbonate or polyolefin. The decrease in optical performance can be reduced. Therefore, the imaging lenses 11 to 15 are effective for the reflow process, are easier to manufacture than the glass mold lens, become inexpensive, and can achieve both low cost and mass productivity of the imaging device incorporating the imaging lens. Therefore, you may form the lenses L1-L5 of this embodiment using the said energy curable resin. The energy curable resin generally refers to a thermosetting resin, an ultraviolet curable resin, or the like.

  In the first to fifth embodiments, the principal ray incident angle of the light beam incident on the imaging surface I of the image sensor 51 is not necessarily designed to be sufficiently small in the peripheral portion of the imaging surface I. However, with recent technology, it has become possible to reduce shading by reviewing the arrangement of the color filters of the image sensor 51 and the on-chip microlens array. Specifically, if the pitch of the arrangement of the color filters and the on-chip microlens array is set slightly smaller than the pixel pitch of the image pickup surface I of the image pickup device 51, the pixel is closer to the periphery of the image pickup surface I. Since the color filter and the on-chip microlens array shift to the optical axis AX side of the imaging lens 10 (11 to 15), the obliquely incident light beam can be efficiently guided to the light receiving unit of each pixel. Thereby, the shading which generate | occur | produces in the image pick-up element 51 can be restrained small. The said Examples 1-5 are the design examples aiming at further size reduction about the part by which the above-mentioned request | requirement was eased.

  Further, in this specification, “convex surface in the vicinity of the optical axis” means a point (for example, 0.05 mm) away from the optical axis AX regardless of the numerical value of the function defining the shape of the surface. If the sag amount of the lens surface is the object side surface of the lens, it means a surface having a positive value and a negative value on the image side surface. Conversely, “concave surface near the optical axis” means a negative value if the sag amount of the surface at a point (for example, 0.05 mm) away from the optical axis AX by a minute amount is an object side surface of the lens. Then, it means a surface that takes a positive value. If a discontinuous shape different from the function of the optical surface is added to the center of the lens surface for the purpose of detecting the amount of eccentricity of the lens or adjusting the eccentricity, the discontinuous shape The sag amount is calculated using a function of the original optical surface. If the approximate curvature radius when the shape measurement value near the center of the lens (specifically, the central region within 10% of the lens outer diameter) is fitted by the least square method is positive, the optical axis AX It can be regarded as a convex surface in the vicinity. For example, when a secondary aspherical coefficient is used, a curvature radius that takes into account the secondary aspherical coefficient in the reference curvature radius of the aspherical definition formula can be regarded as a paraxial curvature radius (for example, reference literature). (See pages 41 to 42 of “Lens Design Method” by K. Matsui, Kyoritsu Publishing Co., Ltd.).

Claims (16)

From the object side,
A first lens having a positive refractive power, a convex surface facing the object side in the vicinity of the optical axis, and a curvature that is stronger on the object side surface than on the image side surface;
A second lens having negative refractive power and having a meniscus shape with a concave surface facing the object side in the vicinity of the optical axis or a concave shape on the object side in the vicinity of the optical axis;
A third lens;
A fourth lens having a positive refractive power;
A fifth lens having negative refractive power and a biconcave shape in the vicinity of the optical axis,
An aperture stop is disposed closer to the object side than the second lens;
The image side surface of the second lens has a shape having a diverging action in the peripheral portion,
The amount of sag on the object side surface of the third lens is a negative value at the periphery,
The image side surface of the fifth lens has an aspherical shape, and has an extreme value at a position other than the intersection with the optical axis,
An imaging lens that satisfies the following conditional expression.
0.55 <f1 / f <0.95 (1)
0.35 <d14 / EPD <0.55 (2)
However,
f1: Focal length of the first lens f: Focal length of the entire imaging lens d14: Distance on the optical axis from the object side surface of the first lens to the image side surface of the second lens EPD: Entrance pupil of the entire imaging lens system diameter The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.30 <r1 / f <0.50 (3)
However,
r1: radius of curvature of the object side surface of the first lens f: focal length of the entire imaging lens system The imaging lens according to claim 1, wherein the imaging lens satisfies the following conditional expression.
−1.20 <f / f23 <−0.15 (4)
However,
f: Focal length of the entire imaging lens system f23: Composite focal length of the second lens and the third lens The imaging lens according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
−2.0 <(r3 + r4) / (r3−r4) ≦ −1.0 (5)
However,
r3: radius of curvature of the object side surface of the second lens r4: radius of curvature of the image side surface of the second lens   The imaging lens according to any one of claims 1 to 4, wherein a sag amount on the image side surface of the third lens is a negative value in a peripheral portion.   The imaging lens according to claim 1, wherein the third lens has a negative refractive power.   The imaging lens according to claim 6, wherein the third lens has a shape with a concave surface facing the image side in the vicinity of the optical axis. The imaging lens according to claim 6, wherein the following conditional expression is satisfied.
0.0 <| f2 / f3 | <1.00 (6)
However,
f2: focal length of the second lens f3: focal length of the third lens The imaging lens according to any one of claims 1 to 8, which satisfies the following conditional expression.
15 <ν3 <45 (7)
However,
ν3: Abbe number of the third lens The imaging lens according to any one of claims 1 to 9, wherein the following conditional expression is satisfied.
20 <ν1-ν2 <70 (8)
However,
ν1: Abbe number of the first lens ν2: Abbe number of the second lens The imaging lens according to claim 1, wherein the imaging lens satisfies the following conditional expression.
f / EPD <1.95 (9)
However,
f: Focal length of the entire imaging lens system EPD: Entrance pupil diameter of the entire imaging lens system   The imaging lens according to claim 1, wherein the aperture stop is disposed between the first lens and the second lens.   The imaging lens according to claim 1, wherein the aperture stop is disposed closer to the object side than the first lens.   The imaging lens according to claim 1, further comprising a lens having substantially no power.   An imaging device comprising the imaging lens according to claim 1 and an imaging element.   A portable terminal comprising the imaging device according to claim 15.

Images