JP2015125405A - Image capturing lens, lens unit, image capturing device, digital still camera, and mobile terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an image capturing lens which has a reduced chief ray angle of rays focused on a peripheral section of an image sensor and a sufficient distance secured between the image sensor and the image capturing lens and which is wide angle, well corrected for aberrations, and configured with six lenses; an image capturing device, digital still camera, and mobile terminal having the same.SOLUTION: An image capturing lens is for forming an image of an object on an imaging plane of an image sensor and is configured with six lenses comprising, in order from the object side, a first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens, the first lens having negative refractive power, and the first and second lenses having negative composite refractive power. At least either of an object-side surface of the first lens and an image-side surface of the sixth lens is an aspherical surface, the aspherical surface being shaped to have an aspherical surface sag amount having an extremum at a position other than an intersection of the aspherical surface and an optical axis on the optical surface.

Description

  The present invention relates to a wide-angle imaging lens used in an imaging device, an imaging device including the imaging lens, a digital still camera including the imaging device, and a portable terminal.

  In recent years, digital still cameras and portable terminals equipped with an imaging device using a solid-state imaging device such as a CCD (Charge Coupled Device) type image sensor or a CMOS (Complementary Metal Oxide Semiconductor) type image sensor have become widespread. However, in addition to the convenience and design of these imaging devices, the general user needs to improve the image quality. Therefore, the solid-state imaging device is made smaller and has higher pixels, and the imaging lens Despite being small in size, higher optical performance tends to be required. In addition, in order to enable imaging of a short-distance subject, there is a tendency that a wide-angle imaging lens having a focal length of 28 mm or less in terms of a 35 mm photograph, that is, a field angle of 75 degrees or more is preferred. As an imaging lens for such applications, there is a six-lens imaging lens that can satisfactorily suppress various aberrations that become conspicuous as a result of widening of the angle and can achieve higher performance than imaging lenses with four or five lenses. Proposed.

  As a six-lens imaging lens, a first lens having positive refractive power in order from the object side, a convex surface facing the object side, a second lens having positive refractive power, and a third lens having positive refractive power An imaging lens including a lens, a fourth lens having positive or negative refractive power, a fifth lens having positive refractive power, and a sixth lens having negative refractive power is known (for example, Patent Document 1). ). In addition, a first lens having negative refractive power in order from the object side, a convex surface on the object side and a concave surface on the image side, a second lens having positive refractive power, and a first lens having positive or negative refractive power An imaging lens including three lenses, a fourth lens having a negative refractive power, a fifth lens having a negative refractive power, and a sixth lens having a positive or negative refractive power is known (Patent Document 2). .

US Patent Publication No. 2013/0279021 Chinese Patent No. 202844391

  In general, an optical low-pass filter, an infrared cut filter, and a cover glass that protects the image sensor are disposed between the image lens and the image sensor. However, in the image lenses disclosed in Patent Document 1 and Patent Document 2, 0 is used. Only a thin infrared cut filter of about 2 mm is provided, and it can be said that the configuration is relatively poor. In particular, since the distance between the sixth lens closest to the image sensor and the image sensor is relatively narrow, for example, if a cover glass has to be further arranged, there is not enough space, and manufacturing errors that may occur in each member In view of the above, there is a problem in that there is a risk of causing interference between members. Such a problem of interference tends to become more prominent with a so-called wide-angle lens having a small focal length with respect to the size of the image sensor. On the other hand, it is possible to avoid interference by thinning the parallel flat plate of the optical low-pass filter, infrared cut filter and cover glass, but thinning the parallel flat plate while maintaining high optical performance significantly increases the cost. Will be invited. Therefore, in order to manufacture the imaging device at a low cost, it is preferable to increase the distance between the sixth lens of the imaging lens and the imaging element as much as possible while suppressing the overall length.

  In addition, the imaging lenses disclosed in Patent Literature 1 and Patent Literature 2 have a chief ray angle (CRA) that is focused on the periphery of the imaging device, which is as large as 20 ° or more. There is a problem in that the image quality is lowered due to the occurrence of color unevenness due to a decrease (peripheral light amount decrease) and color mixing characteristics deterioration. Here, in order to suppress the degradation of image quality, a technique for optimizing the microlens arranged on the surface of the image sensor according to the CRA of the imaging lens has been developed, but the degradation of the image quality is completely corrected. Therefore, it is preferable to use an imaging lens with suppressed CRA in order to inexpensively manufacture an imaging device capable of obtaining a high-quality image.

  The present invention has been made in view of the above-described problems, suppresses the chief ray angle of the light beam condensed on the periphery of the image sensor, can secure a sufficient interval between the image sensor and the image pickup lens, and has a wide angle and good aberration. It is an object of the present invention to provide an imaging lens having a six-lens configuration corrected to the above, an imaging device including the imaging lens, a lens unit, a digital still camera, and a portable terminal.

  The imaging lens according to claim 1 is an imaging lens for forming a subject image on an imaging surface of an imaging element, and sequentially from the object side, a first lens, a second lens, a third lens, and a fourth lens. The first lens has a negative refractive power, the first lens and the second lens have a negative combined refractive power, At least one of the object side surface of the first lens and the image side surface of the sixth lens is an aspheric surface, and the aspheric sag amount is an extreme value at a position on the optical surface other than the intersection of the aspheric surface and the optical axis. It is characterized by having a shape.

  According to the present invention, the first lens has a negative refractive power, and the first lens and the second lens have a negative combined refractive power, so that the focal length with respect to the size of the image sensor is small. A wide-angle lens can be configured as a so-called retrofocus type lens, which increases the back focus, so that the interval between the imaging lens and the imaging surface can be widened. Space can be secured.

  Further, by making at least one of the object side surface of the first lens and the image side surface of the sixth lens an aspherical surface, various aberrations can be favorably corrected over the entire screen. Furthermore, since the aspheric sag amount has an extreme value at a position other than the intersection of the aspheric surface and the optical axis within the effective diameter, the chief ray angle (CRA) at the periphery of the image sensor can be suppressed. . Note that “the aspheric sag amount has an extreme value” means that the height in the direction perpendicular to the optical axis from the optical axis to any point on the aspheric cross section is h, and the reference position (aspherical surface to that point) First-order differential (dX (h) / dh) = 0, where X (h) is the distance in the optical axis direction (aspherical surface sag amount) from the surface apex of A or the point on the optical axis of the aspheric surface) The point represented by.

Here, in the imaging lens of the present invention, various aberrations on the imaging surface must be corrected well. For example, barrel distortion (distortion) that becomes noticeable with a wide-angle lens having a small focal length is suppressed to such an extent that a distortion image can be corrected satisfactorily in the imaging apparatus. At this time, the optical distortion (D) is D ≧ −25% over the entire image height, and more preferably D ≧ −20%. Here, the optical distortion is defined by the following expression, which is a pincushion type when positive and a barrel distortion when negative.
D = y−y ₀ / y ₀ * 100 (%)
However,
y: actual image height y ₀ : ideal image height

  According to a second aspect of the present invention, there is provided the imaging lens according to the first aspect of the invention, wherein the object side surface of the first lens is an aspheric surface, and an aspheric sag is provided at a position other than the intersection of the aspheric surface and the optical axis. The quantity is a shape having an extreme value.

  By making the object side surface of the first lens an aspherical surface, various aberrations at the periphery of the screen can be corrected well. Furthermore, the principal ray angle (CRA) at the periphery of the image sensor can be suppressed by forming the shape of the aspheric sag amount having an extreme value at a position other than the intersection of the aspheric surface and the optical axis.

  According to a third aspect of the present invention, in the image pickup lens according to the first or second aspect, the image-side surface of the sixth lens is an aspherical surface, and is not positioned at a position other than the intersection of the aspherical surface and the optical axis. The spherical sag amount has an extreme value.

  By making the object-side surface of the sixth lens an aspherical surface, various aberrations at the periphery of the screen can be corrected well, and the position at which the sixth lens is closest to the imaging surface can be controlled. Therefore, the distance between the sixth lens and the imaging surface can be increased. Furthermore, the principal ray angle (CRA) at the periphery of the image sensor can be suppressed by forming the shape of the aspheric sag amount having an extreme value at a position other than the intersection of the aspheric surface and the optical axis.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the image side surface of the first lens is an aspherical surface, and other than the intersection of the aspherical surface and the optical axis. The aspheric sag amount has an extreme value at the position.

  By making the image side surface of the first lens an aspherical surface, various aberrations at the periphery of the screen can be corrected well. Furthermore, the principal ray angle (CRA) at the periphery of the image sensor can be suppressed by forming the shape of the aspheric sag amount having an extreme value at a position other than the intersection of the aspheric surface and the optical axis. Note that an aspherical sag amount is present at a position other than the intersection with the optical axis on the object side surface of the first lens, the image side surface of the first lens, and the surface other than the object side surface of the sixth lens. It may be an aspherical shape having extreme values.

The imaging lens of Claim 5 satisfies the following conditional expressions in the invention in any one of Claims 1-4, It is characterized by the above-mentioned.
fb / f> 0.4 (1)
However,
fb: Back focus (air equivalent distance) (mm)
f: Total focal length (mm) of the entire imaging lens system

Expression (1) is a conditional expression for appropriately setting the back focus. By satisfying the expression (1), the sixth lens and the imaging surface are not brought too close to each other, and a space for arranging an optical low-pass filter, an infrared cut filter, and a cover glass for protecting the imaging element can be secured. it can. Here, the back focus is a distance on the optical axis between the image-side surface of the sixth lens and the imaging surface, and an optical low-pass filter, an infrared cut filter, a cover glass for protecting the imaging device, and the like are arranged. In such a case, these are calculated as air conversion distances. Moreover, it is more preferable to satisfy the following conditional expressions.
fb / f> 0.45 (1 ′)

The imaging lens of Claim 6 satisfies the following conditional expressions in the invention in any one of Claims 1-5, It is characterized by the above-mentioned.
d6 / f> 0.3 (2)
However,
d6: Distance between the sixth lens and the imaging surface of the imaging device (air equivalent distance) (mm)
f: Total focal length (mm) of the entire imaging lens system

Expression (2) is a conditional expression for appropriately setting the distance between the imaging lens and the image plane. By satisfying the expression (2), the sixth lens and the imaging surface are not brought too close to each other, and a space for arranging an optical low-pass filter, an infrared cut filter, and a cover glass for protecting the imaging element can be secured. it can. Here, d6 is a distance from the position where the aspherical sag amount of the sixth lens is closest to the image side to the imaging surface, and an optical low-pass filter, an infrared cut filter, a cover glass for protecting the imaging element, and the like are arranged. If these are to be calculated, these are calculated as air conversion distances. In addition, from the above viewpoint, the following conditional expressions are more preferable.
d6 / f> 0.35 (2 ′)

  The imaging lens according to claim 7 is the invention according to any one of claims 1 to 6, wherein the second lens has a positive refractive power, and the third lens has a positive refractive power, The fourth lens has a negative refractive power, the fifth lens has a positive refractive power, and the sixth lens has a negative refractive power.

  Of the six-lens configuration, three lenses are positive lenses and three lenses are negative lenses, so that Petzval sum and chromatic aberration can be easily corrected, and an imaging lens having good imaging performance up to the peripheral portion is obtained. be able to. Further, a positive refractive power is formed by combining the first lens to the fifth lens, and the sixth lens has a negative refractive power, so that a so-called telephoto type lens configuration can be obtained, and the total length of the imaging lens can be increased. It can be set as the structure advantageous for size reduction.

  The imaging lens according to claim 8 is the invention according to any one of claims 1 to 6, wherein the second lens has a negative refractive power, and the third lens has a positive refractive power, The fourth lens has a negative refractive power, the fifth lens has a positive refractive power, and the sixth lens has a negative refractive power.

  Since the second lens has a negative refractive power, the negative combined refractive power of the first lens and the second lens can be increased, and in a wide-angle lens having a small focal length with respect to the size of the image sensor, a so-called retro-reflective power is obtained. Since a focus type lens configuration can be obtained, thereby increasing the back focus, the distance between the imaging lens and the imaging surface can be widened, so that a sufficient space for installing an infrared cut filter, a cover glass, or the like can be secured. Further, a positive refractive power is formed by combining the first lens to the fifth lens, and the sixth lens has a negative refractive power, so that a so-called telephoto type lens configuration can be obtained, and the total length of the imaging lens can be increased. It can be set as the structure advantageous for size reduction.

  An imaging lens according to a ninth aspect is characterized in that, in the invention according to any one of the first to eighth aspects, an angle of view is 75 degrees or more.

  In the case of a wide-angle imaging lens having an angle of view of 75 degrees or more, that is, a focal length of 28 mm or less in terms of a 35 mm size photograph, the distance between the image side surface of the sixth lens and the imaging surface becomes short, and an optical low-pass filter The space for arranging the infrared cut filter and the cover glass for protecting the image pickup device tends to be narrow. However, according to the present invention, since the first lens and the second lens have a negative combined refractive power, the back focus is sufficiently large, and even a wide-angle imaging lens is located on the image side of the sixth lens. Sufficient space can be secured.

  A lens unit according to a tenth aspect is characterized in that the imaging lens according to any one of the first to ninth aspects is assembled to a barrel that holds the imaging lens.

  An image pickup apparatus according to an eleventh aspect includes an image pickup element that photoelectrically converts a subject image and the lens unit according to the tenth aspect.

  A digital still camera according to a twelfth aspect includes the imaging device according to the eleventh aspect.

  According to a thirteenth aspect of the present invention, there is provided a mobile terminal including the imaging device according to the eleventh aspect.

  It is preferable that at least four of the six lenses constituting the imaging lens are plastic lenses from the viewpoint of manufacturing at a low cost. Further, it is more preferable that at least five lenses are plastic lenses.

  The six lenses constituting the imaging lens may include glass lenses. By including the glass lens, the imaging lens is resistant to deterioration in imaging performance due to manufacturing errors that occur during assembly into the unit. Moreover, it is also preferable from the viewpoint of suppressing deterioration in imaging performance when an environmental change such as temperature occurs.

  Since the amount of captured light increases as the pixel size of the image sensor increases, generally, the larger the image sensor size, the higher the quality of the image. Specifically, an image sensor having a size of 1 / 2.3 type (imaging surface diagonal length of about 8 mm) or more is preferable to an image sensor having a size of 1/3 type (image surface diagonal length of about 6 mm) or less. . More preferably, it is an image pickup element of 1 / 1.7 type (diagonal length of imaging surface diagonal length: about 9 mm) or more.

  According to the present invention, a six-lens imaging lens in which the principal ray angle of the light beam condensed on the periphery of the imaging device is suppressed, a sufficient interval between the imaging device and the imaging lens can be secured, and aberrations are corrected favorably at a wide angle. And an imaging device provided with an imaging lens, a digital still camera, and a portable terminal can be provided.

It is a perspective view of the imaging unit 50 concerning this Embodiment. 3 is a diagram schematically showing a cross section along the optical axis of an imaging optical system of the imaging unit 50. FIG. It is the front view (a) of the smart phone as a portable terminal to which an imaging unit is applied, and the back view (b) of the smart phone to which the imaging unit is applied. It is a control block diagram of the smart phone of FIG. 3 is a cross-sectional view in the optical axis direction of the imaging lens of Example 1. FIG. FIG. 4 is an aberration diagram of Example 1 (spherical aberration (a), astigmatism (b), distortion (c)). 2 is a graph showing a chief ray angle (CRA) of a light beam with respect to an image height in Example 1, where the horizontal axis is the image height and the vertical axis is the CRA. FIG. 3 is a diagram illustrating an aspherical shape of a second surface (object-side surface of the first lens) of Example 1, where the vertical axis represents the height h from the optical axis and the horizontal axis represents the sag amount X. FIG. 3 is a diagram illustrating an aspherical shape of a third surface (image side surface of the first lens) of Example 1, in which the vertical axis indicates the height h from the optical axis and the horizontal axis indicates the sag amount X. FIG. 14 is a diagram illustrating the aspherical shape of the fourteenth surface (image side surface of the sixth lens) of Example 1, where the vertical axis represents the height h from the optical axis and the horizontal axis represents the sag amount X. FIG. 6 is a cross-sectional view in the optical axis direction of the imaging lens of Example 2. FIG. 6 is an aberration diagram of Example 2 (spherical aberration (a), astigmatism (b), distortion (c)). FIG. 5 is a graph showing a chief ray angle (CRA) of a light beam with respect to an image height in Example 2, where the horizontal axis is the image height and the vertical axis is the CRA. FIG. 6 is a diagram illustrating the aspherical shape of the second surface (object side surface of the first lens) of Example 2, with the vertical axis representing the height h from the optical axis and the horizontal axis representing the sag amount X. FIG. 6 is a diagram illustrating the aspherical shape of the third surface (image side surface of the first lens) of Example 2, in which the vertical axis represents the height h from the optical axis and the horizontal axis represents the sag amount X. FIG. 14 is a diagram illustrating the aspherical shape of the fourteenth surface (image side surface of the sixth lens) of Example 2, with the vertical axis representing the height h from the optical axis and the horizontal axis representing the sag amount X. 6 is a cross-sectional view in the optical axis direction of the imaging lens of Embodiment 3. FIG. FIG. 6 is an aberration diagram of Example 3 (spherical aberration (a), astigmatism (b), distortion (c)). FIG. 6 is a graph showing a chief ray angle (CRA) of a light beam with respect to an image height in Example 3, where the horizontal axis is the image height and the vertical axis is the CRA. FIG. 6 is a diagram illustrating the aspherical shape of the second surface (object side surface of the first lens) of Example 3, with the vertical axis representing the height h from the optical axis and the horizontal axis representing the sag amount X. FIG. 6 is a diagram illustrating the aspherical shape of the third surface (image side surface of the first lens) of Example 3, in which the vertical axis represents the height h from the optical axis and the horizontal axis represents the sag amount X. FIG. 14 is a diagram illustrating the aspherical shape of the fourteenth surface (image side surface of the sixth lens) of Example 3, with the vertical axis representing the height h from the optical axis and the horizontal axis representing the sag amount X.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an imaging unit (imaging device) 50 according to the present embodiment, and FIG. 2 is a diagram schematically showing a cross section along the optical axis of the imaging lens of the imaging unit 50.

  As shown in FIGS. 1 and 2, the imaging unit 50 captures a subject image on a CMOS type imaging device 51 as a solid-state imaging device having a photoelectric conversion unit 51 a and a photoelectric conversion unit (imaging surface) 51 a of the imaging device 51. An imaging lens 10 to be held, a lens barrel 53 that holds the imaging lens 10, a parallel plate-shaped IR cut filter F and a cover glass CG that are supported by the sensor cover 54 and disposed between the imaging lens 10 and the imaging element 51, A sensor cover 54 that holds the IR cut filter F and the cover glass CG, an actuator 55 that drives the imaging lens 10 together with the lens barrel 53 with respect to the sensor cover 54 in the optical axis direction, and supports the sensor cover 54 and the imaging element 51. And a housing 56 disposed on the substrate 52 and covering the imaging lens 10.

  As shown in FIG. 2, the imaging element 51 has a photoelectric conversion part 51 a as a light receiving part in which pixels (photoelectric conversion elements) are two-dimensionally arranged at the center of the plane on the light receiving side. A signal processing circuit (not shown) is formed around the periphery. Such a signal processing circuit includes a drive 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. In addition, a large number of pads (not shown) are arranged in the vicinity of the outer edge of the plane on the light receiving side of the image sensor 51, and are connected to the substrate 52 via wires (not shown). The image sensor 51 converts the signal charge from the photoelectric conversion unit 51a into an image signal such as a digital YUV signal, and outputs it to a predetermined circuit on the substrate 52 through a wire. Here, Y is a luminance signal, U (= R−Y) is a color difference signal between red and the luminance signal, and V (= BY) is a color difference signal between blue and the luminance signal. Note that the image sensor is not limited to the above CMOS image sensor, and other devices such as a CCD may be used.

  The imaging lens 10 disposed in the lens barrel 53 constitutes a lens unit, and in order from the object side, a first lens L1, a second lens L2, an aperture stop S, a third lens L3, a fourth lens L4, a fifth lens. It consists of a lens L5 and a sixth lens L6, and the flange portions are abutted with each other via a spacer SP, thereby maintaining the inter-axis distance.

  The operation of the imaging unit 50 described above will be described. FIG. 3 is a diagram illustrating a state in which the imaging unit 50 is mounted on the smartphone 100 as a mobile terminal. FIG. 4 is a control block diagram of the smartphone 100.

  In the imaging unit 50, for example, the object-side end surface of the housing 56 is provided on the back surface of the smartphone 100 (see FIG. 3B), and is disposed at a position corresponding to the back side of the touch panel 70.

  The imaging unit 50 is connected to the control unit 101 of the smartphone 100 and outputs an image signal such as a luminance signal or a color difference signal to the control unit 101 side.

  On the other hand, as shown in FIG. 4, the smartphone 100 performs overall control of each unit, and also inputs a control unit (CPU) 101 that executes a program corresponding to each process, and inputs a number and the like with a key. Unit 60, a liquid crystal display unit 70 for displaying captured images in addition to predetermined data, a wireless communication unit 80 for realizing various information communication with an external server, a system program for mobile phone 100, Obtained by a storage unit (ROM) 91 storing various processing programs and necessary data such as a terminal ID, and various processing programs and data executed by the control unit 101, or processing data, or the imaging unit 50 And a temporary storage unit (RAM) 92 that is used as a work area for temporarily storing imaging data and the like.

  The smartphone 100 operates by operating the input key unit 60, and touches an icon 71 or the like displayed on the touch panel (display unit) 70, whereby the imaging unit 50 can be operated to perform imaging. Here, focusing is performed by the actuator 55 serving as a focus mechanism displacing the imaging lens 10 in the optical axis direction. In particular, at the time of short-distance imaging, the actuator 55 moves the entire imaging lens 10 toward the object side, thereby focusing on a short-distance subject.

  The image signal input from the imaging unit 50 according to the release performed at an appropriate timing is subjected to image processing to be described later in the control unit 101, and is stored in the storage unit 92 by the control system of the smartphone 100, Alternatively, it is displayed on the touch panel 70, and further transmitted to the outside as video information via the wireless communication unit 80.

  In the present embodiment, the entire imaging lens 10 is extended forward at the time of short-distance imaging. For example, the first lens L1 to the fifth lens L5 of the imaging lens 10 are the first group, and the sixth lens L6 is the first lens. As the second group, the second lens group may be always fixed, and the first lens group may be extended toward the object side during short-distance imaging, or the first lens group and the second lens group may be disposed toward the object side during short-distance imaging. Although it extends, the extension amount (T1) of the first lens group may be larger than the extension amount (T2) of the second lens group.

[Example]
Examples of the imaging lens of the present invention will be shown below. Symbols used in each example are as follows. Unless otherwise indicated, the unit of value for distance is mm.
f: Focal length of the entire imaging lens system fb: Back focus (air conversion distance)
F: F number 2Y: Diagonal length of the imaging surface of the imaging element FOV: Angle of view R: Radius of curvature d: Axial distance Nd: Refractive index νd of lens material with respect to d-line νd: Abbe number of lens material f1: First lens Focal length f2: Focal length of second lens f3: Focal length of third lens f4: Focal length of fourth lens f5: Focal length of fifth lens f6: Focal length of sixth lens f12: First lens and second lens Synthetic focal length d6 of the lens: Distance between the position of the sixth lens closest to the image plane and the image plane (air conversion distance)

  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 image side is plus), and the height in the direction perpendicular to the optical axis is h, and is expressed by the following “Equation 1”.

ただし、
Ａｉ：ｉ次の非球面係数
Ｒ ：曲率半径
Ｋ ：円錐定数

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

  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 radius of curvature that takes into account the secondary aspherical coefficient in the reference curvature radius of the aspherical definition formula can be regarded as the paraxial curvature radius. (For example, refer to P41-42 of “Lens Design Method” written by Yoshiya Matsui (Kyoritsu Publishing Co., Ltd.) as a reference)

Example 1
The specifications of the imaging lens of Example 1 are shown below.
f = 4.67mm
fb = 2.31 mm
F = 2.88
2Y = 9.33mm
FOV = 90 °

The surface data of the imaging lens of Example 1 is shown below.
Surface number R (mm) d (mm) Nd νd Effective radius (mm)
1 ∞ ∞
2 * -4.374 0.77 1.5305 55.7 2.67
3 * -6.394 0.15 2.10
4 * 2.440 0.94 1.6346 23.9 1.57
5 * 2.121 0.55 1.03
6 (Aperture) ∞ 0.15 0.77
7 * 13.573 1.20 1.5305 55.7 0.92
8 * -2.714 0.56 1.28
9 * -3.414 0.60 1.6346 23.9 1.54
10 * 15.148 0.20 2.11
11 * -609.613 1.82 1.7720 50.0 2.38
12 * -2.474 0.18 2.71
13 * 3.760 1.14 1.5305 55.7 3.67
14 * 1.774 1.13 3.80
15 ∞ 0.30 1.5163 64.1 3.88
16 ∞ 0.20 3.91
17 ∞ 0.50 1.5163 64.1 3.93
18 ∞ 0.53 3.97

  Here, the second and third surfaces are the first lenses, the fourth and fifth surfaces are the second lenses, the seventh and eighth surfaces are the third lenses, and the ninth and tenth surfaces are the fourth lenses. The eleventh and twelfth surfaces represent the fifth lens, and the thirteenth and fourteenth surfaces represent the sixth lens. Both the second surface and the third surface have a convex shape on the image side near the optical axis, and the first lens has a meniscus shape convex on the image side. Both the thirteenth surface and the fourteenth surface have a convex shape toward the object side, and the sixth lens has a meniscus shape that is convex toward the object side.

The aspheric coefficient of Example 1 is shown below.
Second side
K = -5.34580E + 00, A4 = 3.55921E-02, A6 = -8.35358E-03, A8 = 1.48349E-03, A10 = -1.80887E-04, A12 = 1.32819E-05, A14 = -4.33192E -07
Third side
K = -1.38774E + 01, A4 = 4.78295E-02, A6 = -1.35766E-02, A8 = 2.36763E-03, A10 = -2.15698E-04, A12 = 8.25505E-06, A14 = -1.10536E -08
4th page
K = 6.91590E-02, A4 = 2.97538E-03, A6 = -1.16170E-03, A8 = -1.62615E-03, A10 = 6.69805E-04
5th page
K = 9.59742E-01, A4 = -2.05091E-02, A6 = 2.11283E-02, A8 = -1.11875E-02, A10 = -2.16708E-03, A12 = 7.49300E-03
7th page
A4 = -1.03463E-02, A6 = -3.53802E-03, A8 = 3.09003E-03
8th page
A4 = -2.80292E-02, A6 = 9.22517E-03, A8 = -1.74559E-02, A10 = 1.74250E-02, A12 = -8.40329E-03, A14 = 1.44858E-03
9th page
K = -4.37488E + 00, A4 = -6.07809E-02, A6 = 2.15084E-02, A8 = -4.79510E-03, A10 = 3.27404E-03, A12 = -1.39264E-03, A14 = 1.73223E -04
10th page
A4 = -1.99606E-02, A6 = 1.51081E-03, A8 = 1.82620E-03, A10 = -5.85764E-04, A12 = 7.40190E-05, A14 = -3.97111E-06
11th page
A4 = 1.99505E-02, A6 = -1.32170E-02, A8 = 4.18286E-03, A10 = -7.42897E-04, A12 = 7.22136E-05, A14 = -2.98225E-06
12th page
K = -4.06339E + 00, A4 = -8.13305E-03, A6 = 1.83913E-03, A8 = -6.89620E-04, A10 = 1.47500E-04, A12 = -1.36298E-05, A14 = 4.94380E -07
13th page
K = -5.27880E + 00, A4 = -1.09290E-02, A6 = -7.22040E-04, A8 = 3.28767E-04, A10 = -3.01692E-05, A12 = 1.22309E-06, A14 = -1.93842 E-08
14th page
K = -3.82395E + 00, A4 = -1.68203E-02, A6 = 2.09781E-03, A8 = -2.18788E-04, A10 = 1.38088E-05, A12 = -3.93774E-07, A14 = 3.19918E -09

The focal length of each lens is shown below. At this time, since the refractive power is the reciprocal of the focal length, the positive / negative of the refractive power is the same as the positive / negative of the focal length.
f1 = −29.96 mm
f2 = 172.99mm
f3 = 4.36mm
f4 = -4.29mm
f5 = 3.20mm
f6 = −7.87 mm
f12 = -30.33mm

Values corresponding to the conditional expression of the imaging lens of Example 1 are shown below.
fb / f = 0.49
d6 / f = 0.36

  The imaging lens of Example 1 is a wide-angle lens with an angle of view of 90 degrees, which satisfies the conditional expressions (1) and (2). Between the sixth lens and the imaging element, an optical low-pass filter, an infrared cut The space | interval which arrange | positions the cover glass which protects a filter and an image pick-up element is ensured.

  In Example 1, the fifth lens is a glass mold lens, and the first to fourth lenses and the sixth lens are plastic lenses.

  In the surface data of the imaging lens of Example 1, the shooting distance is infinity, but the shooting distance is not limited to this in the present invention. For example, the imaging lens is provided with a focus mechanism that corrects a deviation in the imaging position due to a change in the shooting distance by changing the distance (d14) between the 14th surface and the 15th surface on the optical axis, thereby reducing the shooting distance range. Can be spread. In Example 1, when the shooting distance is 80 mm (d1 = 80 mm), the distance between the 14th surface and the 15th surface on the optical axis is 1.39 mm (d14 = 1.39 mm). At this time, the distance between the image-side surface of the sixth lens and the image sensor becomes narrow, but since sufficient distance is secured by satisfying conditional expressions (1) and (2), such a focus is maintained. Proximity shooting with a mechanism is possible.

  5 is a cross-sectional view of the imaging lens of Example 1. FIG. In the figure, L1 is a first lens having negative refractive power, L2 is a second lens having positive refractive power, L3 is a third lens having positive refractive power, L4 is a fourth lens having negative refractive power, L5 is a fifth lens having a positive refractive power, L6 is a sixth lens having a negative refractive power, S is an aperture stop, and I is an imaging surface. F is a parallel plate assuming an optical low-pass filter and an infrared cut filter, and CG is a parallel plate assuming a cover glass that protects the image sensor. Note that the combined refractive power of the first lens L1 and the second lens L2 is negative.

  FIG. 6 is an aberration diagram ((a) spherical aberration, (b) astigmatism, (c) distortion) relating to the imaging lens of Example 1. Various aberrations on the image plane are corrected satisfactorily. Here, the barrel-shaped distortion (distortion) that becomes conspicuous in the wide-angle lens is D ≧ −15% in the entire image height, and the distortion image can be corrected well in the imaging apparatus. In the following aberration diagrams, in the astigmatism diagrams, the solid line S represents the sagittal image plane, and the dotted line M represents the meridional image plane.

  FIG. 7 is a graph showing the chief ray angle (CRA) of the light beam with respect to the image height in Example 1. As shown in FIG. 7, since the CRA is 20 ° or less, it is possible to suppress a decrease in image quality due to a decrease in light collection efficiency (a decrease in peripheral light amount) and color unevenness due to a deterioration in color mixing characteristics.

  8 shows the second surface of the first embodiment (object side surface of the first lens), FIG. 9 shows the third surface of the first embodiment (image side surface of the first lens), and FIG. 10 shows the first surface of the first embodiment. It is a figure which shows the aspherical shape of 14 surfaces (image side surface of a 6th lens). The second surface has an extreme value when the sag amount X is h = 1.67 mm, the third surface has an extreme value when the sag amount X is h = 1.05 mm, and the sag amount X is h = 2. The shape has an extreme value at 74 mm, and the chief ray angle (CRA) at the periphery of the image sensor is suppressed.

(Example 2)
The specifications of the imaging lens of Example 2 are shown below.
f = 4.67mm
fb = 2.31 mm
F = 2.88
2Y = 9.33mm
FOV = 90 °

The surface data of the imaging lens of Example 2 is shown below.
Surface number R (mm) d (mm) Nd νd Effective radius (mm)
1 ∞ ∞
2 * -3.383 0.71 1.5305 55.7 2.52
3 * -4.478 0.15 2.10
4 * 2.711 0.90 1.6346 23.9 1.52
5 * 2.467 0.55 1.03
6 (Aperture) ∞ 0.15 0.77
7 * 10.989 1.20 1.5305 55.7 0.92
8 * -3.033 0.61 1.28
9 * -3.286 0.61 1.6346 23.9 1.53
10 * 15.675 0.20 2.07
11 * 413.846 1.80 1.7720 50.0 2.35
12 * -2.423 0.18 2.68
13 * 3.757 1.11 1.5305 55.7 3.66
14 * 1.727 1.13 3.79
15 ∞ 0.30 1.5163 64.1 3.87
16 ∞ 0.20 3.89
17 ∞ 0.50 1.5163 64.1 3.92
18 ∞ 0.53 3.96

  Here, the second and third surfaces are the first lenses, the fourth and fifth surfaces are the second lenses, the seventh and eighth surfaces are the third lenses, and the ninth and tenth surfaces are the fourth lenses. The eleventh and twelfth surfaces represent the fifth lens, and the thirteenth and fourteenth surfaces represent the sixth lens. Both the second surface and the third surface have a convex shape on the image side near the optical axis, and the first lens has a meniscus shape convex on the image side. Both the thirteenth surface and the fourteenth surface have a convex shape toward the object side, and the sixth lens has a meniscus shape that is convex toward the object side.

The aspheric coefficient of Example 2 is shown below.
Second side
K = -4.96125E + 00, A4 = 3.29575E-02, A6 = -8.49982E-03, A8 = 1.48099E-03, A10 = -1.79752E-04, A12 = 1.33926E-05, A14 = -4.45466E -07
Third side
K = -1.38774E + 01, A4 = 4.13195E-02, A6 = -1.37753E-02, A8 = 2.36060E-03, A10 = -2.15305E-04, A12 = 9.46031E-06, A14 = -1.35059E -07
4th page
K = -3.65867E-02, A4 = 1.03489E-02, A6 = -2.25089E-03, A8 = -1.80133E-03, A10 = 6.92236E-04
5th page
K = 1.43226E + 00, A4 = -1.32097E-02, A6 = 2.48773E-02, A8 = -1.59231E-02, A10 = 8.47464E-04, A12 = 5.30424E-03
7th page
A4 = -5.91692E-03, A6 = -2.01333E-03, A8 = 3.20417E-03
8th page
A4 = -2.86486E-02, A6 = 1.10337E-02, A8 = -1.79294E-02, A10 = 1.74181E-02, A12 = -7.69022E-03, A14 = 1.19404E-03
9th page
K = -4.37488E + 00, A4 = -6.54415E-02, A6 = 2.29663E-02, A8 = -4.51955E-03, A10 = 3.40626E-03, A12 = -1.36181E-03, A14 = 1.37400E -04
10th page
A4 = -2.24761E-02, A6 = 3.42783E-03, A8 = 9.64959E-04, A10 = -3.06005E-04, A12 = 3.08454E-05, A14 = -1.62018E-06
11th page
A4 = 1.94032E-02, A6 = -1.27615E-02, A8 = 4.04634E-03, A10 = -7.28167E-04, A12 = 7.22690E-05, A14 = -3.06427E-06
12th page
K = -4.05993E + 00, A4 = -7.92255E-03, A6 = 1.92544E-03, A8 = -6.92032E-04, A10 = 1.47150E-04, A12 = -1.36380E-05, A14 = 4.91632E -07
13th page
K = -5.27880E + 00, A4 = -1.14781E-02, A6 = -6.60025E-04, A8 = 3.27960E-04, A10 = -3.02505E-05, A12 = 1.22041E-06, A14 = -1.91167 E-08
14th page
K = -3.82395E + 00, A4 = -1.69597E-02, A6 = 2.09390E-03, A8 = -2.15848E-04, A10 = 1.36448E-05, A12 = -3.99806E-07, A14 = 3.64111E -09

The focal length of each lens is shown below. At this time, since the refractive power is the reciprocal of the focal length, the positive / negative of the refractive power is the same as the positive / negative of the focal length.
f1 = −33.52 mm
f2 = 97.59mm
f3 = 4.60mm
f4 = -4.19mm
f5 = 3.11mm
f6 = −7.40 mm
f12 = −43.40mm

The values corresponding to the conditional expression of the imaging lens of Example 2 are shown below.
fb / f = 0.50
d6 / f = 0.36

  The imaging lens of Example 2 is a wide-angle lens with an angle of view of 90 degrees, which satisfies the conditional expressions (1) and (2). Between the sixth lens and the imaging device, an optical low-pass filter, an infrared ray cut-off The space | interval which arrange | positions the cover glass which protects a filter and an image pick-up element is ensured.

  In Example 2, the fifth lens is a glass mold lens, and the first to fourth lenses and the sixth lens are plastic lenses.

  FIG. 11 is a cross-sectional view of the imaging lens of the second embodiment. In the figure, L1 is a first lens having negative refractive power, L2 is a second lens having positive refractive power, L3 is a third lens having positive refractive power, L4 is a fourth lens having negative refractive power, L5 is a fifth lens having a positive refractive power, L6 is a sixth lens having a negative refractive power, S is an aperture stop, and I is an imaging surface. F is a parallel plate assuming an optical low-pass filter and an infrared cut filter, and CG is a parallel plate assuming a cover glass that protects the image sensor. Note that the combined refractive power of the first lens L1 and the second lens L2 is negative.

  FIG. 12 is an aberration diagram ((a) spherical aberration, (b) astigmatism, (c) distortion aberration) applied to the imaging lens of Example 2. Various aberrations on the image plane are corrected satisfactorily. Here, the barrel-shaped distortion (distortion) that becomes conspicuous in the wide-angle lens is D ≧ −15% in the entire image height, and the distortion image can be corrected well in the imaging apparatus.

  FIG. 13 is a graph showing the chief ray angle (CRA) of the light beam with respect to the image height in Example 2. As shown in FIG. 13, since the CRA is 20 ° or less, it is possible to suppress a decrease in image quality due to a decrease in light collection efficiency (a decrease in peripheral light amount) and color unevenness due to a deterioration in color mixing characteristics.

  14 shows the second surface of Example 2 (the object side surface of the first lens), FIG. 15 shows the third surface of Example 2 (the image side surface of the first lens), and FIG. 16 shows the second surface of Example 2. The aspherical shape of 14 surfaces (image side surface of the sixth lens). The fourteenth surface has a shape having an extreme value when the sag amount X is h = 2.74 mm, and suppresses the chief ray angle (CRA) at the periphery of the image sensor.

(Example 3)
The specifications of the imaging lens of Example 3 are shown below.
f = 4.67mm
fb = 2.77 mm
F = 2.88
2Y = 9.33mm
FOV = 90 °

The surface data of the imaging lens of Example 3 is shown below.
Surface number R (mm) d (mm) Nd νd Effective radius (mm)
1 ∞ ∞
2 * -3.393 0.67 1.5305 55.7 2.58
3 * -4.084 0.15 2.10
4 * 2.595 0.91 1.6346 23.9 1.57
5 * 2.210 0.66 1.08
6 (Aperture) ∞ 0.21 0.77
7 * 22.229 1.20 1.5305 55.7 0.92
8 * -2.869 0.55 1.28
9 * -3.346 0.38 1.6346 23.9 1.54
10 * 15.556 0.20 1.98
11 * -84.227 1.74 1.7720 50.0 2.26
12 * -2.409 0.16 2.59
13 * 3.002 0.90 1.5305 55.7 3.55
14 * 1.693 1.59 3.59
15 ∞ 0.30 1.5163 64.1 3.57
16 ∞ 0.20 3.80
17 ∞ 0.50 1.5163 64.1 3.85
18 ∞ 0.53 3.93

  Here, the second and third surfaces are the first lenses, the fourth and fifth surfaces are the second lenses, the seventh and eighth surfaces are the third lenses, and the ninth and tenth surfaces are the fourth lenses. The eleventh and twelfth surfaces represent the fifth lens, and the thirteenth and fourteenth surfaces represent the sixth lens. Both the second surface and the third surface have a convex shape on the image side near the optical axis, and the first lens has a meniscus shape convex on the image side. Both the thirteenth surface and the fourteenth surface have a convex shape toward the object side, and the sixth lens has a meniscus shape that is convex toward the object side.

The aspheric coefficient of Example 3 is shown below.
Second side
K = -6.38067E + 00, A4 = 3.30965E-02, A6 = -8.14287E-03, A8 = 1.46254E-03, A10 = -1.75592E-04, A12 = 1.25609E-05, A14 = -3.96007E -07
Third side
K = -1.38774E + 01, A4 = 4.14267E-02, A6 = -1.23834E-02, A8 = 2.44006E-03, A10 = -2.89569E-04, A12 = 1.97444E-05, A14 = -5.38298E -07
4th page
K = 8.70994E-02, A4 = 6.35303E-03, A6 = -3.63272E-03, A8 = -3.78519E-04, A10 = 4.34011E-04
5th page
K = 6.76916E-01, A4 = -2.25167E-02, A6 = 2.47471E-02, A8 = -1.85660E-02, A10 = 6.99117E-03, A12 = 1.30169E-03
7th page
A4 = -1.14731E-02, A6 = -4.59477E-03, A8 = 1.65754E-03
8th page
A4 = -2.23985E-02, A6 = 7.04992E-03, A8 = -1.49966E-02, A10 = 1.47015E-02, A12 = -6.98138E-03, A14 = 1.17878E-03
9th page
K = -4.37488E + 00, A4 = -6.32978E-02, A6 = 2.54691E-02, A8 = -6.10889E-03, A10 = 2.93815E-03, A12 = -1.15191E-03, A14 = 1.46431E -04
10th page
A4 = -3.27666E-02, A6 = 1.17782E-02, A8 = -2.10605E-03, A10 = 1.92494E-04, A12 = -3.14534E-06, A14 = -1.08320E-06
11th page
A4 = 1.53905E-02, A6 = -9.87912E-03, A8 = 3.30229E-03, A10 = -6.41871E-04, A12 = 7.03989E-05, A14 = -3.33687E-06
12th page
K = -4.00289E + 00, A4 = -9.61364E-03, A6 = 2.40432E-03, A8 = -6.98296E-04, A10 = 1.45625E-04, A12 = -1.35799E-05, A14 = 4.59881E -07
13th page
K = -5.27880E + 00, A4 = -7.22354E-03, A6 = -7.24520E-04, A8 = 3.05678E-04, A10 = -2.95888E-05, A12 = 1.28553E-06, A14 = -2.21633 E-08
14th page
K = -3.82395E + 00, A4 = -1.48691E-02, A6 = 1.84899E-03, A8 = -1.77361E-04, A10 = 1.25851E-05, A12 = -4.41856E-07, A14 = 4.71741E -09

The focal length of each lens is shown below. At this time, since the refractive power is the reciprocal of the focal length, the positive / negative of the refractive power is the same as the positive / negative of the focal length.
f1 = −56.98 mm
f2 = −302.8 mm
f3 = 4.85mm
f4 = −4.26 mm
f5 = 3.17mm
f6 = −9.58 mm
f12 = −41.82mm

The values corresponding to the conditional expression of the imaging lens of Example 3 are shown below.
fb / f = 0.59
d6 / f = 0.39

  The imaging lens of Example 3 is a wide-angle lens having an angle of view of 90 degrees, which satisfies the conditional expressions (1) and (2). Between the sixth lens and the imaging device, an optical low-pass filter, an infrared cut The space | interval which arrange | positions the cover glass which protects a filter and an image pick-up element is ensured.

  In Example 3, the fifth lens is a glass mold lens, and the first to fourth lenses and the sixth lens are plastic lenses.

  FIG. 17 is a sectional view of the imaging lens of Example 3. In the figure, L1 is a first lens having negative refractive power, L2 is a second lens having negative refractive power, L3 is a third lens having positive refractive power, L4 is a fourth lens having negative refractive power, L5 is a fifth lens having a positive refractive power, L6 is a sixth lens having a negative refractive power, S is an aperture stop, and I is an imaging surface. F is a parallel plate assuming an optical low-pass filter and an infrared cut filter, and CG is a parallel plate assuming a cover glass that protects the image sensor. Note that the combined refractive power of the first lens L1 and the second lens L2 is negative.

  FIG. 18 is an aberration diagram (spherical aberration, astigmatism, distortion) relating to the imaging lens of Example 3. Various aberrations on the image plane are corrected satisfactorily. Here, the barrel-shaped distortion (distortion) that becomes conspicuous in the wide-angle lens is D ≧ −15% in the entire image height, and the distortion image can be corrected well in the imaging apparatus.

  FIG. 19 is a graph showing the chief ray angle (CRA) of the light beam with respect to the image height in Example 3. As shown in FIG. 19, since the CRA is 20 ° or less, it is possible to suppress deterioration in image quality due to occurrence of color unevenness due to reduction in light collection efficiency (peripheral light amount reduction) and color mixing characteristics.

  20 shows the second surface of the third embodiment (object side surface of the first lens), FIG. 21 shows the third surface of the third embodiment (image side surface of the first lens), and FIG. 22 shows the third surface of the third embodiment. The aspherical shape of 14 surfaces (image side surface of the sixth lens). The second surface has an extreme value when the sag amount X is h = 1.96 mm, and the third surface has an extreme value when the sag amount X is h = 1.43 mm. The ray angle (CRA) is suppressed.

  Further, the present invention is not limited to the embodiments described in the specification, and it is understood that other embodiments and modifications are included in the art from the embodiments and ideas described in the present specification. It is obvious to For example, even when a dummy lens having substantially no refractive power is further provided, it is within the scope of application of the present invention. Moreover, although the portable terminal which mounts an imaging device was shown as an example, it can also be mounted in a digital still camera.

  The present invention can provide an imaging lens suitable for a portable terminal or a digital still camera.

DESCRIPTION OF SYMBOLS 10 Imaging lens 50 Imaging unit 51 Solid-state image sensor 51a Photoelectric conversion part 52 Substrate 53 Lens tube 54 Sensor cover 55 Actuator 60 Input part 60 Input key part 70 Touch panel 71 Icon 80 Wireless communication part 92 Storage part 100 Smartphone 101 Control part L1-L6 Lens S Aperture stop CG Cover glass F Optical filter

Claims (13)

  An imaging lens for forming a subject image on an imaging surface of an imaging element, and in order from the object side, 6 of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens The first lens has a negative refractive power, the first lens and the second lens have a negative combined refractive power, the object side of the first lens and the sixth lens At least one of the image-side surfaces of the lens is an aspherical surface, and the aspherical sag amount has an extreme value at a position on the optical surface other than the intersection of the aspherical surface and the optical axis. Imaging lens.   2. The object-side surface of the first lens is an aspheric surface, and the aspheric sag amount has an extreme value at a position other than the intersection of the aspheric surface and the optical axis. Imaging lens.   The image-side surface of the sixth lens is an aspherical surface, and the aspherical sag amount has a shape having an extreme value at a position other than the intersection of the aspherical surface and the optical axis. The imaging lens described in 1.   The image-side surface of the first lens is an aspherical surface, and the aspherical sag amount has an extreme value at a position other than the intersection of the aspherical surface and the optical axis. The imaging lens according to any one of the above. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
fb / f> 0.4 (1)
However,
fb: Back focus (air equivalent distance) (mm)
f: Total focal length (mm) of the entire imaging lens system The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
d6 / f> 0.3 (2)
However,
d6: Distance between the sixth lens and the imaging surface of the imaging device (air equivalent distance) (mm)
f: Total focal length (mm) of the entire imaging lens system   The second lens has a positive refractive power, the third lens has a positive refractive power, the fourth lens has a negative refractive power, and the fifth lens has a positive refractive power. The imaging lens according to claim 1, wherein the sixth lens has a negative refractive power.   The second lens has a negative refractive power, the third lens has a positive refractive power, the fourth lens has a negative refractive power, and the fifth lens has a positive refractive power. The imaging lens according to claim 1, wherein the sixth lens has a negative refractive power.   The imaging lens according to any one of claims 1 to 8, wherein an angle of view is 75 degrees or more.   A lens unit comprising the imaging lens according to any one of claims 1 to 9 assembled to a barrel that holds the imaging lens.   An image pickup apparatus comprising: an image pickup device that photoelectrically converts a subject image; and the lens unit according to claim 10.   A digital still camera comprising the imaging device according to claim 11.   A portable terminal comprising the imaging device according to claim 11.

Images