JP5644681B2 - Imaging device and portable terminal - Google Patents

Description

The present invention relates to an imaging lens, an imaging device, and a portable terminal for an imaging device, and in particular, the present invention is a solid-state imaging device such as a CCD-type image sensor or a CMOS-type image sensor having a curved imaging surface. And an imaging apparatus having an imaging lens and a portable terminal using the imaging apparatus.

  In recent years, small-sized imaging devices using solid-state imaging devices such as CCD (Charged Coupled Device) type image sensors or CMOS (Complementary Metal Oxide Semiconductor) type image sensors have become mobile terminals such as mobile phones and PDAs (Personal Digital Assistants), Furthermore, it is also installed in notebook personal computers and the like, and it is possible to transmit not only audio information but also image information to a remote place.

  In the solid-state imaging device used in such an imaging apparatus, in recent years, the pixel size has been reduced, and the imaging device has been increased in size and size. Further, it is possible to curve the imaging surface, and there is a demand for a compact and high-performance imaging lens that is optimal for such an imaging device.

  Here, Patent Document 1 discloses an imaging device in which a solid-state imaging element is curved. According to Patent Document 1, a solid-state imaging device is curved into a polynomial surface shape, thereby correcting the curvature of field and distortion generated by the lens in a well-balanced manner, and providing a compact and high-resolution imaging apparatus. However, since the solid-state imaging device has a CIF size (352 pixels × 288 pixels) and the imaging lens has a single lens configuration, the chromatic aberration is not sufficiently corrected. It is not possible to obtain an imaging device.

  Patent Document 2 and Patent Document 3 disclose an imaging lens having a curved imaging surface, a shooting field angle of about 77 degrees, and a brightness of F5.7 to F6.2 for use in a compact camera or a lens-equipped film unit. Is disclosed. The lens configuration is a rear stop triplet type lens including a positive first lens, a negative second lens, a positive third lens, and an aperture stop. However, if the F value is darker than F5, sufficient performance cannot be obtained, and the triplet type tends to increase the back focus, and the imaging lens and the imaging device are increased in size.

  Patent Documents 2 to 3 are imaging lenses for film cameras, which are designed to improve performance by curving the film surface (imaging surface) in accordance with the curvature of field generated by the lens. Since both are imaging lenses for cameras that use roll films, the film surface is a so-called cylindrical imaging surface that is curved only in the long side direction of the screen due to the structure of the camera. Therefore, although good performance can be obtained in the long side direction of the screen, the imaging surface in the short side direction of the screen remains flat, so performance cannot be improved and deterioration may occur depending on the correction status of field curvature. obtain. It is difficult to obtain high performance over the entire screen by bending only the long side direction of the imaging surface as in Patent Documents 2 to 3.

Furthermore, since Patent Documents 2 to 3 are imaging lenses for film cameras as described above, the principal ray incident angle of the light beam incident on the imaging surface is not necessarily designed to be sufficiently small in the periphery of the imaging surface. . In an imaging lens for forming a subject image on the photoelectric conversion unit of a solid-state image sensor, when the chief ray incident angle of the light beam incident on the imaging surface, so-called telecentric characteristics, deteriorates, the light beam enters the solid-state image sensor obliquely. As a result, a phenomenon (shading) in which the substantial aperture efficiency decreases in the peripheral portion of the imaging surface occurs, and the peripheral light amount becomes insufficient.

JP 2004-356175 A JP-A-8-68935 JP 2000-292688 JP 2010-271541 A

  On the other hand, as a small and high-performance lens, a four-lens imaging lens has been proposed because it can be improved in performance as compared with a lens having two or three lenses. As an example, in Patent Document 4, in order from the object side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a fourth lens having a negative refractive power. A so-called telephoto type imaging lens is disclosed which is made up of lenses and aims to reduce the overall length of the imaging lens (the distance on the optical axis from the most object-side lens surface to the image-side focal point of the entire imaging lens system). Yes. However, the imaging lens described in Patent Document 4 has a chief ray incident angle on the imaging surface of about 25 ° to 30 ° at the maximum, so it cannot be said that the telecentric characteristic is good, and the optical total length is shortened. Is insufficient.

The present invention has been made in view of such problems, and has a four-sheet configuration that can suppress shading with a small size and high performance by utilizing the fact that the imaging surface of the solid-state imaging device is curved. It is an object to obtain an imaging device having an imaging lens and a portable terminal.

The imaging apparatus according to claim 1, chromatic imaging surface, and the solid-state image sensor which is curved to fall toward the object side toward the peripheral portion of the screen, and an imaging lens for forming an object image on the imaging surface And
The imaging lens in order from the object side,
A first lens having a positive refractive power;
A second lens having negative refractive power;
A third lens having a positive refractive power;
A fourth lens having at least one aspheric surface and having positive or negative refractive power;
And satisfying the following conditional expression.
0.5 <f123 / f <1.4 (1)
0.05 <SAGI / Y <0.50 (2)
1.29 ≦ f3 / f <3.5 (6)
However,
f123: Composite focal length from the first lens to the third lens f: Focal length of the entire imaging lens system
SAGI: displacement in the optical axis direction at the maximum image height from a point on the optical axis of the imaging surface
Y: Maximum image height
f3: focal length of the third lens

  An imaging apparatus according to the present invention includes a solid-state imaging device having a photoelectric conversion unit and an imaging lens that forms a subject image on the photoelectric conversion unit of the solid-state imaging device. It is curved. Since the imaging surface of the solid-state imaging device is curved, both miniaturization and high performance can be achieved. If the imaging surface is curved toward the imaging lens, it is advantageous to correct the chief ray incident angle of the light beam incident on the imaging surface, so-called telecentric characteristics. The chief ray incident angle of the light beam incident on the imaging surface is smaller when the imaging surface is curved than when the imaging surface is flat, so the telecentric characteristics are not sufficiently corrected by the imaging lens. However, the aperture efficiency is not reduced, and the occurrence of shading can be suppressed. In addition, correction of field curvature, distortion, and coma becomes easy, and miniaturization becomes possible. Here, in the present invention, the curved shape of the imaging surface is premised on that both the long side direction and the short side direction of the screen are curved so as to fall toward the object side toward the periphery of the screen, The spherical shape does not necessarily have to be a spherical shape, and any surface shape that can be expressed by an arbitrary mathematical expression such as an aspherical shape, a parabolic shape, an XY polynomial surface shape, etc. may be used. By adopting a shape that fits the shape, the performance can be improved over the entire screen.

The imaging lens mounted on the imaging apparatus of the present invention includes, in order from the object side, a first lens having a positive refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power. , At least one surface is an aspherical surface and is composed of a fourth lens having positive or negative refractive power .

Conditional expression (1) is a conditional expression for appropriately setting the combined focal length of the first lens to the third lens. When the value of conditional expression (1) exceeds the lower limit, the positive composite focal length of the first lens to the third lens is not unnecessarily shortened, and performance degradation due to manufacturing errors of the first lens to the third lens is reduced. Sensitivity, so-called error sensitivity, can be reduced. On the other hand, when the value of conditional expression (1) is less than the upper limit, the combined focal length from the first lens to the third lens can be appropriately maintained, and the combined principal point position of the entire lens system is further moved to the object side. Since it can be arranged, it is advantageous for shortening the total length of the imaging lens. More preferably, the range of the following formula is good.
0.6 <f123 / f <1.3 (1) ′
Conditional expression (2) is a conditional expression for appropriately setting the amount of curvature of the imaging surface. When the value of conditional expression (2) exceeds the lower limit, the amount of curvature of the imaging surface can be maintained moderately, and it is possible to prevent an increase in the telecentric characteristics and field curvature correction burden on the imaging lens. Therefore, coma and chromatic aberration can be corrected satisfactorily. On the other hand, when the value of conditional expression (2) is below the upper limit, the amount of curvature of the imaging surface becomes too large, and it is possible to prevent overcorrection of field curvature. Further, it is possible to prevent the final surface of the imaging lens from being too close to the imaging surface, and to ensure a sufficient air space for inserting an IR cut filter or the like. More preferably, the range of the following formula is good.
0.10 <SAGI / Y <0.40 (2) '
Conditional expression (6) is a conditional expression for appropriately setting the focal length of the third lens. When the value of conditional expression (6) exceeds the lower limit, the focal length of the third lens does not become too small, and the occurrence of distortion and coma can be suppressed. On the other hand, when the value of conditional expression (6) is below the upper limit, the focal length of the third lens can be maintained moderately, and the overall length of the imaging lens can be shortened.

The imaging lens according to claim 2 is the invention according to claim 1, wherein the fourth lens has have a negative refractive power.

  This so-called telephoto type lens configuration in which a positive group consisting of a first lens, a second lens, and a third lens and a negative group consisting of a fourth lens are arranged is advantageous in reducing the overall length of the imaging lens. is there.

The imaging apparatus according to claim 3 is the invention according to claim 1 or 2, the image pickup surface that is the curved has a spherical shape, and satisfies the following conditional expression.
−8.0 <RI / Y <−1.0 (3)
However,
RI: radius of curvature of the imaging surface Y: maximum image height

By making the imaging surface spherical, the imaging surface does not have a complicated shape, and the difficulty of the manufacturing process for bending the imaging surface can be reduced. Here, the conditional expression (3) is a conditional expression for appropriately setting the curvature amount of the imaging surface. When the value of the conditional expression (3) exceeds the lower limit, the amount of curvature of the imaging surface can be maintained moderately, and it is possible to prevent an increase in the telecentric characteristics and field curvature correction burden on the imaging lens. Therefore, coma and chromatic aberration can be corrected satisfactorily. On the other hand, if the value of conditional expression (3) is below the upper limit, the amount of curvature of the imaging surface becomes too large, and it is possible to prevent overcorrection of field curvature. Further, it is possible to prevent the final surface of the imaging lens from being too close to the imaging surface, and to ensure a sufficient air space for inserting an IR cut filter or the like. More preferably, the range of the following formula is good.
−7.0 <RI / Y <−1.5 (3) ′

The imaging apparatus according to claim 4, in the invention described in claim 1, wherein the first lens is a shape with a convex surface directed to the object side, characterized by satisfying the following condition And
0.4 <f1 / f <1.3 (4)
However,
f1: Focal length of the first lens f: Focal length of the entire imaging lens system

Conditional expression (4) 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 of conditional expression (4) is less than the upper limit, the refractive power of the first lens can be maintained moderately, and the composite principal point of the first lens to the third lens can be arranged closer to the object side. The overall length of the imaging lens can be shortened. On the other hand, when the value of conditional expression (4) exceeds the lower limit, the refractive power of the first lens does not become unnecessarily large, and high-order spherical aberration and coma generated in the first lens are suppressed to a small value. Can do. More preferably, the range of the following formula is good.
0.5 <f1 / f <1.2 (4) '

The imaging apparatus according to claim 5, in the invention described in claim 1, wherein the second lens is shaped with a concave surface facing the image side, characterized by satisfying the following condition And
.
0 <(r3 + r4) / (r3-r4) <1.0 (5)
However,
r3: radius of curvature of the second lens object side surface r4: radius of curvature of the second lens image side surface

Conditional expression (5) is a conditional expression for appropriately setting the shaping factor of the second lens. When the value of conditional expression (5) exceeds the lower limit, the principal point position of the second lens moves to the image side, the distance between the principal points of the first lens and the second lens increases, and the first lens and the second lens Since the refractive power of the first lens and the second lens can be reduced while maintaining the combined focal length of the lens, the occurrence of each aberration can be suppressed, and the influence of manufacturing errors can be reduced. Mass productivity is improved. On the other hand, when the value of conditional expression (5) is less than the upper limit value, occurrence of higher-order aberrations such as coma flare due to an increase in the radius of curvature of the image side surface can be suppressed. More preferably, the range of the following formula is good.
0 <(r3 + r4) / (r3-r4) <0.80 (5) ′

The imaging apparatus according to claim 6 is the invention according to claim 1, wherein said third lens is a biconvex shape.

The imaging apparatus according to claim 7 is the invention according to claim 1, characterized by satisfying the following conditional expression.
φp / φm <5.0 (7)
However,
φp: power of the fourth lens in the paraxial axis φm: power of the fourth lens in the position of the maximum ray height

Conditional expression (7) is a conditional expression for appropriately setting the ratio of the power at the maximum ray height of the fourth lens to the paraxial power. In order to satisfactorily correct off-axis field curvature and astigmatism, it is desirable that the power at the periphery of the fourth lens be in the range of conditional expression (7). If the upper limit of conditional expression (7) is exceeded, off-axis aberration correction will be insufficient, and good performance may not be obtained. More preferably, the range of the following formula is good.
φm / φp <4.0 (7) '

  Here, the lens power φm at the position of the maximum ray height is such that when parallel rays are incident from an infinite distance on the object side to the effective radius Hm on the side surface of the symmetrical lens object, and the tilt angle after passing through the lens is ξ, φm = tanξ / Hm. Φp is given by the reciprocal of the focal length on the fourth lens paraxial. (Reference: JP 2004-326097 A)

The imaging apparatus according to claim 8 is the invention according to any one of claims 1 to 7, the image side from the object side apex of the first lens, the object side surface position by Ri of the first lens periphery An aperture stop is arranged on the body side.

In the image side of the object side surface vertex of the first lens, by disposing the aperture diaphragm on the object side positions by Ri product side of the first lens peripheral portion, it is possible to distance the exit pupil position of the imaging surface, good telecentricity Can be secured.

An imaging device according to a ninth aspect is characterized in that, in the invention according to any one of the first to seventh aspects, an aperture stop is disposed between the first lens and the second lens.

  By arranging an aperture stop between the first lens and the second lens, the refraction angle of the peripheral marginal ray passing through the side surface of the first lens object does not become too large, and both downsizing of the imaging lens and good aberration correction are achieved. can do.

An imaging device according to a tenth aspect is the invention according to any one of the first to ninth aspects, further including a lens having substantially no power. That is, even when a dummy lens having substantially no power is added to the configuration of claim 1, it is within the scope of application of the present invention.

A portable terminal according to an eleventh aspect includes the imaging device according to any one of the first to tenth aspects .

  By using the imaging device of the present invention, a smaller and higher performance portable terminal can be obtained.

According to the present invention, by utilizing a solid-state imaging device imaging surface is curved, the small type and high performance, is possible to obtain an imaging device and a portable terminal equipped with the imaging lens of the four lenses that can suppress shading it can.

It is a perspective view of the imaging device concerning this embodiment. It is the figure which showed typically the cross section along the optical axis of the imaging lens of the imaging device which concerns on this Embodiment. It is an external view of the mobile telephone which is an example of the portable terminal provided with the imaging device which concerns on this Embodiment. 2 is a cross-sectional view of an imaging lens of Example 1. FIG. FIG. 6 is an aberration diagram (spherical aberration, astigmatism, distortion) of the imaging lens of Example 1. 2 is a meridional coma aberration diagram of Example 1. FIG. 6 is a cross-sectional view of an imaging lens of Example 2. FIG. FIG. 6 is an aberration diagram (spherical aberration, astigmatism, distortion) of the imaging lens of Example 2. 6 is a meridional coma aberration diagram of Example 2. FIG. 6 is a cross-sectional view of an imaging lens of Example 3. FIG. FIG. 6 is an aberration diagram (spherical aberration, astigmatism, distortion) of the imaging lens of Example 3. FIG. 6 is a meridional coma aberration diagram of Example 3. 6 is a cross-sectional view of an imaging lens of Example 4. FIG. FIG. 10 is an aberration diagram (spherical aberration, astigmatism, distortion) of the imaging lens of Example 4. 6 is a meridional coma aberration diagram of Example 4. FIG. 6 is a cross-sectional view of an imaging lens of Example 5. FIG. FIG. 10 is an aberration diagram (spherical aberration, astigmatism, distortion) of the imaging lens of Example 5. FIG. 6 is a meridional coma aberration diagram of Example 5. 6 is a cross-sectional view of an imaging lens of Example 6. FIG. FIG. 10 is an aberration diagram (spherical aberration, astigmatism, distortion) of the imaging lens of Example 6. 6 is a meridional coma aberration diagram of Example 6. FIG. 10 is a cross-sectional view of an imaging lens of Example 7. FIG. FIG. 10 is an aberration diagram (spherical aberration, astigmatism, distortion) of the imaging lens of Example 7. FIG. 6 is a meridional coma aberration diagram of Example 7.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a top view of an imaging apparatus 50 according to the present embodiment, and FIG. 2 is a cross-sectional view obtained by cutting the configuration of FIG. 1 along a cross section including an optical axis.

  As illustrated in FIG. 1 or FIG. 2, the imaging device 50 includes a CMOS type imaging device 51 as a solid-state imaging device having a photoelectric conversion unit 51 a and an imaging lens that captures a subject image on the photoelectric conversion unit 51 a on the imaging device 51. 10 and a casing 53 made of a light shielding member having an opening for light incidence from the object side, and these are integrally formed.

  As shown in FIG. 2, the image sensor 51 is spherically curved with a predetermined radius of curvature, and a pixel (photoelectric conversion element) is two-dimensionally arranged at the center of the curved light receiving side surface. A photoelectric conversion unit 51a as a unit is formed, and a signal processing circuit 51b is formed around the photoelectric conversion unit 51a. The signal processing circuit 51b includes a driving circuit unit that sequentially drives each pixel to obtain a signal charge, an A / D conversion unit that converts each signal charge into a digital signal, and a signal that forms an image signal output using the digital signal. It consists of a processing unit and the like. Note that the image pickup element is not limited to the above-described CMOS type image sensor, and may be one to which another one such as a CCD is applied.

  An optical low-pass filter F is fixed to the photoelectric conversion unit 51 a side of the image sensor 51 via a spacer B, and the optical low-pass filter F or the side surface of the image sensor 51 is fixed to the housing 53. The optical low-pass filter F is a flat plate here, but may be curved in accordance with the photoelectric conversion unit 51a.

  A plurality of external electrodes 52 used for connection to an external circuit are formed on the other surface of the image sensor 51 (surface opposite to the photoelectric conversion unit 51a). The external electrode 52 and an external circuit (not shown) (for example, a control circuit included in a host device on which the imaging device is mounted) are connected to receive a voltage or a clock signal for driving the imaging device 51 from the external circuit. In addition, it is possible to output a digital YUV signal to an external circuit.

  Although not shown, a substrate is disposed on the surface opposite to the photoelectric conversion unit 51a of the image sensor 51, the substrate and the image sensor 51 are connected by wire bonding, and an external surface is connected to the surface of the substrate opposite to the image sensor. A plurality of external electrodes used for connection with a circuit may be formed.

  As shown in FIG. 2, the housing 53 made of a light-shielding member is screwed into a lens frame 55 that holds the imaging lens 10 on the photoelectric conversion unit 51 a side of the imaging element 51, whereby the imaging lens 10 is Adjustable in the optical axis direction.

  The imaging lens 10 includes, in order from the object side, an aperture stop S, a positive first lens L1, a negative second lens L2, a positive third lens L3, and a positive or negative fourth lens L4. A subject image is formed on the photoelectric conversion surface 51a. In addition, the dashed-dotted line in FIG. 2 is the optical axis of each lens L1-L4.

  Any one of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the optical low-pass filter F is coated with an infrared light cut coat. Although not shown, an infrared light cut filter may be disposed in front of the optical low-pass filter instead of the infrared cut coat.

  The lenses L1 to L4 constituting the imaging lens 10 are held by a lens frame 55 made of a light shielding member. Each of the lenses L1 to L4 has an outer diameter that increases from the object side toward the image side, and a disc-shaped light shielding member SH1 having an opening in the center is disposed between the flange portions of the lenses L1 and L2. Has been. Further, the light shielding member SH2 is fixed to the lens frame 55 so as to contact the image side flange portion of the lens L2. Further, a light shielding member SH3 is provided between the lenses L3 and L4. The surfaces of the light shielding members SH1, SH2, and SH3 that cut unnecessary light may be stepped or roughened. Further, a light shielding member may be disposed between the fourth lens L4 and the optical low-pass filter F. By arranging the light shielding member outside the light beam path, it is possible to suppress the occurrence of ghost and flare. In the case of the imaging apparatus shown in FIG. 2, H in the figure is the height of the imaging lens in the optical axis direction of the imaging apparatus.

  FIG. 3 is an external view of a mobile phone 100 that is an example of a mobile terminal including the imaging device 50 according to the present embodiment. In the mobile phone 100 shown in the figure, an upper casing 71 as a case having display screens D1 and D2 and a lower casing 72 having an operation button 60 as an input unit are connected via a hinge 73. Yes. The imaging device 50 is built below the display screen D <b> 2 in the upper casing 71, and is arranged so that the imaging device 50 can capture light from the outer surface side of the upper casing 71. Note that the position of the imaging device may be disposed above or on the side of the display screen D2 in the upper casing 71. Of course, the mobile phone is not limited to a folding type.

(Example)
Next, examples suitable for the above-described embodiment will be described. However, the present invention is not limited to the following examples. Symbols used in each example are as follows.
f: Focal length of the entire imaging lens fB: Back focus F: F number 2Y: Diagonal length of the imaging surface of the solid-state imaging device
ENTP: Entrance pupil position (distance from first surface to entrance pupil position)
EXTP: Exit pupil position (distance from imaging surface to exit pupil position)
H1: Front principal point position (distance from the first surface to the 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: spacing between axial upper surfaces Nd: refractive index νd of lens material with respect to d-line: Abbe number of lens material

  In each embodiment, the surface described with “*” after each surface number is a surface having an aspheric shape, and the shape of the aspheric surface has the vertex of the surface as the origin and the X axis in the optical axis direction. The height in the direction perpendicular to the optical axis is represented by the following “Equation 1”.

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

Example 1
Lens data is shown in Table 1. 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). 4 is a sectional view of the lens of Example 1. FIG. In the figure, L1 is a first lens, L2 is a second lens, L3 is a third lens, L4 is a fourth lens, S is an aperture stop, F is an optical low-pass filter, IR cut filter, a solid-state image sensor sealing glass, and the like. It is an assumed parallel plate, and I represents an imaging surface. 5A is a spherical aberration diagram of Example 1, FIG. 5B is an astigmatism diagram, and FIG. 5C is a distortion diagram. FIG. 6 is a meridional coma aberration diagram. Here, in the spherical aberration diagram, the coma aberration diagram, and the meridional coma aberration diagram, g represents the amount of spherical aberration with respect to the g line, and d represents the amount of spherical aberration with respect to the d line. In the astigmatism diagram, the solid line S represents the sagittal plane, and the dotted line M represents the meridional plane (the same applies hereinafter). The aperture stop S is on the object side of the first lens L1.

[table 1 ]
Example 1
f = 5.78mm fB = 0.88mm F = 2.88 2Y = 7.128mm
ENTP = 0mm EXTP = -3.77mm H1 = -1.41mm H2 = -4.9mm

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (Aperture) ∞ -0.12 1.00
2 * 2.503 1.03 1.53180 56.0 1.04
3 * -4.655 0.05 1.16
4 * -5.683 0.40 1.58300 30.0 1.18
5 * 4.189 0.90 1.27
6 * 15.416 0.89 1.53 180 56.0 2.03
7 * -5.207 1.69 2.05
8 * -6.184 0.52 1.53180 56.0 2.44
9 * 26.685 0.20 2.90
10 ∞ 0.15 1.51630 64.1 3.45
11 ∞ 0.87 3.49
12 (imaging surface) -15.201

Aspheric coefficient

2nd side 6th side
K = 0.20668E + 00 K = 0.44775E + 02
A4 = -0.45215E-02 A4 = -0.11350E-02
A6 = -0.30318E-02 A6 = 0.10797E-02
A8 = -0.10255E-03 A8 = 0.55500E-03
A10 = -0.46269E-03 A10 = -0.78770E-04
A12 = 0.38768E-05

3rd surface 7th surface
K = 0.23020E-02 K = -0.27977E + 02
A4 = 0.40995E-02 A4 = -0.20548E-01
A6 = 0.88443E-02 A6 = 0.86374E-02
A8 = -0.28733E-02 A8 = -0.16996E-02
A10 = -0.94745E-04 A10 = 0.36981E-03
A12 = -0.18637E-04

4th side 8th side
K = -0.36926E + 02 K = 0.49501E + 01
A4 = -0.18770E-01 A4 = -0.38583E-01
A6 = 0.28390E-01 A6 = 0.55910E-02
A8 = -0.76595E-02 A8 = 0.11518E-03
A10 = 0.83678E-03 A10 = -0.20463E-03
A12 = 0.26886E-04

5th surface 9th surface
K = 0.96482E + 00 K = -0.44208E + 03
A4 = 0.58465E-02 A4 = -0.33633E-01
A6 = 0.14042E-01 A6 = 0.59291E-02
A8 = -0.73500E-02 A8 = -0.70521E-03
A10 = 0.35023E-02 A10 = 0.34026E-04
A12 = -0.69564E-03 A12 = -0.10257E-06

Single lens data

Lens Start surface Focal length (mm)
1 2 3.222
2 4 -4.076
3 6 7.431
4 8 -9.389

(Example 2)
Table 2 shows the lens data. FIG. 7 is a sectional view of the lens of Example 2. In the figure, L1 is a first lens, L2 is a second lens, L3 is a third lens, L4 is a fourth lens, S is an aperture stop, F is an optical low-pass filter, IR cut filter, a solid-state image sensor sealing glass, and the like. It is an assumed parallel plate, and I represents an imaging surface. FIG. 8A is a spherical aberration diagram of Example 2, FIG. 8B is an astigmatism diagram, and FIG. 8C is a distortion diagram. FIG. 9 is a meridional coma aberration diagram. The aperture stop S is on the object side of the first lens L1.

[Table 2]
Example 2

f = 4.68mm fB = 1.03mm F = 2.88 2Y = 7.128mm
ENTP = 0mm EXTP = -3.82mm H1 = 0.16mm H2 = -3.65mm

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (Aperture) ∞ -0.01 0.81
2 * 3.484 1.59 1.54470 56.2 0.85
3 * -4.706 0.06 1.30
4 * -7.921 0.40 1.63200 23.4 1.33
5 * 6.574 0.26 1.54
6 * 12.758 1.28 1.54470 56.2 1.77
7 * -5.217 0.81 1.98
8 * 3.523 0.73 1.54470 56.2 2.30
9 * 2.618 0.40 3.06
10 ∞ 0.15 1.51630 64.1 3.47
11 ∞ 1.03 3.52
12 (Imaging surface) -9.840

Aspheric coefficient

2nd side 6th side
K = 0.26831E + 00 K = 0.19634E + 02
A4 = -0.49640E-02 A4 = -0.55092E-02
A6 = -0.35249E-02 A6 = 0.37558E-02
A8 = 0.41901E-02 A8 = -0.64978E-03
A10 = -0.30654E-02 A10 = 0.16145E-03
A12 = -0.16946E-04

3rd surface 7th surface
K = 0.34256E + 01 K = -0.29973E + 01
A4 = -0.34442E-02 A4 = -0.25718E-01
A6 = 0.10763E-01 A6 = 0.83725E-02
A8 = -0.59391E-02 A8 = -0.20725E-02
A10 = 0.37082E-03 A10 = 0.44531E-03
A12 = -0.20066E-04

4th side 8th side
K = -0.17415E + 02 K = -0.11658E + 02
A4 = -0.23971E-01 A4 = -0.41840E-01
A6 = 0.19654E-01 A6 = -0.12657E-02
A8 = -0.88369E-02 A8 = 0.82939E-03
A10 = 0.11981E-02 A10 = -0.12381E-03
A12 = 0.92004E-05

5th surface 9th surface
K = -0.19173E + 02 K = -0.64839E + 00
A4 = -0.59634E-02 A4 = -0.55582E-01
A6 = 0.11854E-01 A6 = 0.72567E-02
A8 = -0.55652E-02 A8 = -0.83289E-03
A10 = 0.14173E-02 A10 = 0.59449E-04
A12 = -0.14817E-03 A12 = -0.19144E-05

Single lens data

Lens Start surface Focal length (mm)
1 2 3.946
2 4 -5.624
3 6 6.973
4 8 -26.180

Example 3
Table 3 shows lens data. FIG. 10 is a sectional view of the lens of Example 3. In the figure, L1 is a first lens, L2 is a second lens, L3 is a third lens, L4 is a fourth lens, S is an aperture stop, and I is an imaging surface. 11A is a spherical aberration diagram of Example 3, FIG. 11B is an astigmatism diagram, and FIG. 11C is a distortion diagram. FIG. 12 is a meridional coma aberration diagram. The aperture stop S is on the object side of the first lens L1.

[Table 3]
Example 3

f = 3.77mm fB = 1.27mm F = 2.8 2Y = 5.744mm
ENTP = 0mm EXTP = -2.18mm H1 = -0.35mm H2 = -2.5mm

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (Aperture) ∞ -0.03 0.67
2 * 1.941 0.53 1.54470 56.2 0.71
3 * -12.609 0.05 0.82
4 * -15.100 0.30 1.63200 23.4 0.86
5 * 4.353 0.32 0.93
6 * 34.147 0.66 1.54470 56.2 1.22
7 * -4.010 0.90 1.31
8 * 3.771 0.60 1.54470 56.2 1.78
9 * 2.525 1.24 2.27
10 (imaging surface) -9.119

Aspheric coefficient

2nd side 6th side
K = -0.68875E + 00 K = -0.23459E + 02
A4 = -0.12853E-01 A4 = -0.17684E-01
A6 = -0.52162E-01 A6 = 0.30999E-01
A8 = 0.27637E-01 A8 = 0.82705E-02
A10 = -0.55353E-01 A10 = -0.35244E-02
A12 = 0.62240E-04

3rd surface 7th surface
K = 0.50000E + 02 K = -0.32505E + 00
A4 = -0.10330E + 00 A4 = -0.50179E-01
A6 = 0.74303E-01 A6 = 0.31260E-01
A8 = -0.40486E-01 A8 = -0.40429E-02
A10 = 0.20244E-01 A10 = 0.51426E-02
A12 = 0.18280E-03

4th side 8th side
K = -0.22519E + 02 K = -0.16264E + 02
A4 = -0.17286E-01 A4 = -0.10138E + 00
A6 = 0.79880E-01 A6 = -0.24632E-02
A8 = 0.42798E-01 A8 = 0.44097E-02
A10 = -0.28936E-01 A10 = -0.84127E-03
A12 = 0.18354E-03

5th surface 9th surface
K = 0.94031E + 01 K = -0.72066E + 00
A4 = 0.53517E-01 A4 = -0.10906E + 00
A6 = 0.44420E-01 A6 = 0.20776E-01
A8 = -0.37207E-01 A8 = -0.35735E-02
A10 = 0.23040E-01 A10 = 0.43364E-03
A12 = -0.10128E-01 A12 = -0.23964E-04

Single lens data

Lens Start surface Focal length (mm)
1 2 3.128
2 4 -5.314
3 6 6.629
4 8 -16.893

Example 4
Table 4 shows the lens data. FIG. 13 is a sectional view of the lens of Example 4. In the figure, L1 is a first lens, L2 is a second lens, L3 is a third lens, L4 is a fourth lens, S is an aperture stop, and I is an imaging surface. 14A is a spherical aberration diagram of Example 4, FIG. 14B is an astigmatism diagram, and FIG. 14C is a distortion diagram. FIG. 15 is a meridional coma aberration diagram. The aperture stop S is on the object side of the first lens L1.

[Table 4]
Example 4

f = 3.77mm fB = 1.52mm F = 2.8 2Y = 5.744mm
ENTP = 0mm EXTP = -2.24mm H1 = -0.01mm H2 = -2.25mm

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (Aperture) ∞ 0.07 0.67
2 * 2.414 0.61 1.54470 56.2 0.78
3 * -6.963 0.21 0.92
4 * -6.891 0.50 1.63200 23.4 1.01
5 * 6.621 0.24 1.12
6 * 5.080 0.61 1.54470 56.2 1.42
7 * 38.385 0.43 1.55
8 * 2.116 0.70 1.54470 56.2 1.79
9 * 2.287 1.50 2.25
10 * (Imaging surface) -8.498

Aspheric coefficient

2nd side 6th side
K = -0.20704E + 01 K = -0.91604E + 01
A4 = -0.27221E-01 A4 = -0.23651E-01
A6 = -0.48137E-01 A6 = 0.92425E-02
A8 = 0.13821E-02 A8 = 0.77904E-02
A10 = -0.55764E-01 A10 = -0.54959E-02
A12 = 0.11377E-02

3rd surface 7th surface
K = 0.35439E + 02 K = 0.42309E + 02
A4 = -0.12696E + 00 A4 = -0.83829E-01
A6 = 0.30338E-01 A6 = 0.43637E-01
A8 = -0.26796E-01 A8 = -0.86494E-02
A10 = -0.26313E-02 A10 = 0.15484E-02
A12 = -0.12148E-03

4th side 8th side
K = 0.21888E + 02 K = -0.69345E + 01
A4 = -0.95721E-01 A4 = -0.90125E-01
A6 = 0.11337E + 00 A6 = -0.23591E-02
A8 = 0.93111E-02 A8 = 0.45847E-02
A10 = -0.11726E-01 A10 = -0.78287E-03
A12 = 0.12231E-03

5th side 9th side
K = -0.29589E + 02 K = -0.66240E + 00
A4 = -0.36693E-01 A4 = -0.10620E + 00
A6 = 0.93988E-01 A6 = 0.20570E-01
A8 = -0.39750E-01 A8 = -0.36171E-02
A10 = 0.21120E-01 A10 = 0.42612E-03
A12 = -0.62407E-02 A12 = -0.24544E-04

10th page
K = -0.28506E + 01
A4 = 0.40989E-03
A6 = 0.13817E-04
A8 = 0.24635E-07
A10 = -0.83635E-07
A12 = -0.15480E-07

Single lens data

Lens Start surface Focal length (mm)
1 2 3.368
2 4 -5.268
3 6 10.681
4 8 21.225

(Example 5)
Table 5 shows the lens data. FIG. 16 is a sectional view of the lens of Example 5. In the figure, L1 is a first lens, L2 is a second lens, L3 is a third lens, L4 is a fourth lens, S is an aperture stop, and I is an imaging surface. FIG. 17A is a spherical aberration diagram of Example 5, FIG. 17B is an astigmatism diagram, and FIG. 17C is a distortion diagram. FIG. 18 is a meridional coma aberration diagram. The aperture stop S is on the object side of the first lens L1. The fifth embodiment is an embodiment that does not belong to the present invention.

[Table 5]
Example 5

f = 3.77mm fB = 1.86mm F = 2.8 2Y = 5.744mm
ENTP = 0mm EXTP = -2.12mm H1 = 0.19mm H2 = -1.92mm

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (Aperture) ∞ 0.01 0.67
2 * 2.441 0.57 1.54470 56.2 0.71
3 * -4.907 0.09 0.85
4 * -7.730 0.30 1.63200 23.4 0.91
5 * 7.135 0.38 1.00
6 * -9.102 0.94 1.54470 56.2 1.37
7 * -1.494 0.28 1.38
8 * -11.994 0.40 1.54470 56.2 1.47
9 * 2.884 1.83 1.99
10 (Imaging surface) -9.443

Aspheric coefficient

2nd side 6th side
K = -0.23154E + 01 K = -0.50000E + 02
A4 = -0.25043E-01 A4 = 0.14876E-02
A6 = -0.72675E-01 A6 = 0.34718E-01
A8 = 0.21654E-01 A8 = 0.62594E-02
A10 = -0.59724E-01 A10 = -0.49021E-02
A12 = 0.71466E-03

3rd surface 7th surface
K = 0.26366E + 02 K = -0.31032E + 01
A4 = -0.11508E + 00 A4 = -0.50615E-01
A6 = 0.66611E-01 A6 = 0.21893E-01
A8 = -0.43570E-01 A8 = -0.89335E-02
A10 = 0.61226E-01 A10 = 0.62006E-02
A12 = 0.16910E-02

4th side 8th side
K = 0.40282E + 02 K = -0.50000E + 02
A4 = -0.32281E-01 A4 = -0.80693E-01
A6 = 0.64987E-01 A6 = -0.10915E-01
A8 = 0.39301E-01 A8 = 0.32314E-02
A10 = -0.15000E-01 A10 = -0.71436E-03
A12 = 0.29826E-03

5th side 9th side
K = 0.13893E + 02 K = -0.37404E + 00
A4 = 0.56552E-01 A4 = -0.10580E + 00
A6 = 0.50388E-01 A6 = 0.21369E-01
A8 = -0.52279E-01 A8 = -0.35956E-02
A10 = 0.11343E-01 A10 = 0.40603E-03
A12 = 0.65470E-02 A12 = -0.34408E-04

Single lens data

Lens Start surface Focal length (mm)
1 2 3.077
2 4 -5.826
3 6 3.144
4 8 -4.229

(Example 6)
Table 6 shows the lens data. FIG. 19 is a sectional view of the lens of Example 6. In the figure, L1 is a first lens, L2 is a second lens, L3 is a third lens, L4 is a fourth lens, S is an aperture stop, and I is an imaging surface. 20A is a spherical aberration diagram of Example 6, FIG. 20B is an astigmatism diagram, and FIG. 20C is a distortion diagram. FIG. 21 is a meridional coma aberration diagram. The aperture stop S is between the first lens L1 and the second lens L2. The sixth embodiment is an embodiment that does not belong to the present invention.

[Table 6]
Example 6

f = 3.48mm fB = 1.82mm F = 2.45 2Y = 5.744mm
ENTP = 0.45mm EXTP = -1.98mm H1 = 0.74mm H2 = -1.66mm

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 ∞ 0.00 1.18
2 * 2.383 0.62 1.54470 56.2 1.03
3 * -27.053 0.01 0.82
4 (Aperture) ∞ 0.15 0.66
5 * -90.439 0.30 1.63200 23.4 0.77
6 * 14.723 0.49 0.88
7 * -4.125 0.97 1.54470 56.2 1.35
8 * -1.452 0.05 1.57
9 * 3.731 0.40 1.61550 25.2 2.03
10 * 1.862 1.81 2.31
11 (Imaging surface) -7.000

Aspheric coefficient

2nd surface 7th surface
K = -0.18146E + 01 K = -0.45751E + 00
A4 = -0.11238E-01 A4 = 0.25690E-01
A6 = -0.30746E-01 A6 = -0.88706E-01
A8 = 0.10694E-01 A8 = 0.11499E + 00
A10 = -0.21214E-01 A10 = -0.42740E-01
A12 = 0.43753E-02

3rd surface 8th surface
K = 0.50000E + 02 K = -0.67502E + 01
A4 = -0.50657E-01 A4 = -0.22802E + 00
A6 = -0.49064E-01 A6 = 0.18391E + 00
A8 = 0.65050E-01 A8 = -0.12891E + 00
A10 = -0.12985E + 00 A10 = 0.58370E-01
A12 = 0.84402E-01 A12 = -0.95961E-02

5th side 9th side
K = 0.50000E + 02 K = -0.35206E + 00
A4 = 0.68018E-01 A4 = -0.18176E + 00
A6 = -0.12063E-01 A6 = 0.61277E-01
A8 = -0.49062E-01 A8 = -0.33819E-02
A10 = 0.56240E-01 A10 = -0.27661E-02
A12 = -0.43945E-01 A12 = 0.70086E-03
A14 = -0.54457E-04

6th page 10th page
K = -0.36470E + 02 K = -0.72398E + 01
A4 = 0.12730E + 00 A4 = -0.94630E-01
A6 = -0.13318E-01 A6 = 0.36323E-01
A8 = 0.51169E-01 A8 = -0.84703E-02
A10 = -0.97708E-01 A10 = 0.12047E-02
A12 = 0.42755E-01 A12 = -0.91611E-04
A14 = 0.25018E-05

Single lens data

Lens Start surface Focal length (mm)
1 2 4.051
2 5 -20.012
3 7 3.647
4 9 -6.578

(Example 7)
Table 7 shows the lens data. FIG. 22 is a sectional view of the lens of Example 7. In the figure, L1 is a first lens, L2 is a second lens, L3 is a third lens, L4 is a fourth lens, S is an aperture stop, and I is an imaging surface. FIG. 23A is a spherical aberration diagram of Example 7, FIG. 23B is an astigmatism diagram, and FIG. 23C is a distortion diagram. FIG. 24 is a meridional coma aberration diagram. The aperture stop S is on the object side of the first lens L1.

[Table 7]
Example 7

f = 3.52mm fB = 1.04mm F = 2.8 2Y = 5.744mm
ENTP = 0mm EXTP = -2.89mm H1 = 0.37mm H2 = -2.48mm

Surface number R (mm) D (mm) Nd νd Effective radius (mm)
1 (Aperture) ∞ -0.05 0.67
2 * 2.379 0.98 1.54470 56.2 0.63
3 * -2.832 0.05 0.89
4 * -3.018 0.30 1.63200 23.4 0.92
5 * -235.830 0.27 1.07
6 * -28.219 0.71 1.54470 56.2 1.44
7 * -5.145 0.77 1.59
8 * 7.781 0.68 1.54470 56.2 2.02
9 * 8.171 1.03 2.37
10 (imaging surface)-5.000

Aspheric coefficient

2nd side 6th side
K = -0.12146E + 01 K = 0.46169E + 02
A4 = -0.12881E-01 A4 = -0.23820E-01
A6 = -0.21281E-01 A6 = 0.29470E-01
A8 = 0.14977E-01 A8 = 0.66328E-02
A10 = -0.45090E-01 A10 = -0.58642E-02
A12 = 0.79812E-03

3rd surface 7th surface
K = 0.77739E + 01 K = 0.35966E + 01
A4 = -0.87252E-01 A4 = -0.50298E-01
A6 = 0.12099E + 00 A6 = 0.32881E-01
A8 = 0.10957E-01 A8 = -0.89186E-02
A10 = -0.15074E-02 A10 = 0.58415E-02
A12 = -0.12032E-02

4th side 8th side
K = 0.83353E + 01 K = -0.50000E + 02
A4 = 0.60055E-02 A4 = -0.80417E-01
A6 = 0.11417E + 00 A6 = 0.42909E-02
A8 = 0.13321E-01 A8 = 0.57286E-02
A10 = -0.64017E-02 A10 = -0.22401E-02
A12 = 0.27244E-03

5th surface 9th surface
K = 0.50000E + 02 K = 0.10651E + 02
A4 = 0.75714E-01 A4 = -0.73689E-01
A6 = 0.26850E-01 A6 = 0.14902E-01
A8 = -0.37066E-01 A8 = -0.29045E-02
A10 = 0.35778E-01 A10 = 0.40555E-03
A12 = -0.15596E-01 A12 = -0.36409E-04

Single lens data

Lens Start surface Focal length (mm)
1 2 2.543
2 4 -4.840
3 6 11.426
4 8 185.132

  Table 8 summarizes the values of the conditional expressions described in the claims.

  Regarding the meaning of the paraxial radius of curvature described in the claims and the examples, in the actual lens measurement scene, in the vicinity of the center of the lens (specifically, the central region within 10% of the lens outer diameter) ) Can be regarded as the paraxial curvature radius when fitting the shape measurement value in the least square method. 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.).

  The present invention is not limited to the embodiments described in the specification, and other embodiments and modifications are apparent to those skilled in the art from the embodiments and ideas described in the present specification. It is. For example, even when a dummy lens having substantially no power is further provided, it is within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Imaging lens 50 Imaging device 51a Photoelectric conversion part 51b Signal processing circuit 52 External electrode 53 Housing | casing 55 Mirror frame 60 Operation button 71 Upper housing | casing 72 Lower housing | casing 73 Hinge 100 Cellular phone B Spacer F Optical low-pass filter D1, D2 display Screen L1 First lens L2 Second lens L3 Third lens L4 Fourth lens S Aperture stop SH1 Light blocking member SH2 Light blocking member SH3 Light blocking member

Claims (11)

The imaging surface, possess a solid-state imaging device which has been bent to fall toward the object side toward the peripheral portion of the screen, and an imaging lens for forming an object image on the imaging surface,
The imaging lens in order from the object side,
A first lens having a positive refractive power;
A second lens having negative refractive power;
A third lens having a positive refractive power;
A fourth lens having at least one aspheric surface and having positive or negative refractive power;
Consists, ZoSo location shooting you and satisfies the following conditional expression.
0.5 <f123 / f <1.4 (1)
0.05 <SAGI / Y <0.50 (2)
1.29 ≦ f3 / f <3.5 (6)
However,
f123: Composite focal length from the first lens to the third lens f: Focal length of the entire imaging lens system
SAGI: displacement in the optical axis direction at the maximum image height from a point on the optical axis of the imaging surface
Y: Maximum image height
f3: focal length of the third lens The imaging apparatus according to claim 1, wherein the fourth lens has have a negative refractive power. The imaging apparatus according to claim 1, wherein the curved imaging surface has a spherical shape and satisfies the following conditional expression.
−8.0 <RI / Y <−1.0 (3)
However,
RI: radius of curvature of the imaging surface Y: maximum image height The imaging device according to claim 1, wherein the first lens has a shape with a convex surface directed toward the object side, and satisfies the following conditional expression.
0.4 <f1 / f <1.3 (4)
However,
f1: Focal length of the first lens f: Focal length of the entire imaging lens system The imaging device according to claim 1, wherein the second lens has a shape with a concave surface facing the image side, and satisfies the following conditional expression.
0 <(r3 + r4) / (r3-r4) <1.0 (5)
However,
r3: radius of curvature of the second lens object side surface r4: radius of curvature of the second lens image side surface The third lens The imaging apparatus according to any one of claims 1 to 5, characterized in that a biconvex shape. The imaging apparatus according to claim 1, wherein the following conditional expression is satisfied.
φp / φm <5.0 (7)
However,
φp: power of the fourth lens in the paraxial axis φm: power of the fourth lens in the position of the maximum ray height In the image side of the object side surface vertex of the first lens, according to claim 1, characterized in that a aperture diaphragm on the object side positions by Ri product side of the first lens periphery Imaging device . The imaging apparatus according to claim 1, wherein an aperture stop is disposed between the first lens and the second lens. The imaging apparatus according to claim 1, further comprising a lens having substantially no power. A portable terminal comprising the imaging device according to claim 1.