JP5963003B2 - Imaging lens and imaging apparatus - Google Patents

Description

  The present invention relates to an imaging lens suitable for an imaging apparatus using a solid-state imaging device such as a CCD (Charge Coupled Devices) type image sensor or a CMOS (Complementary Meta 1-Oxide Semiconductor) type image sensor.

  In recent years, mobile phones (including smartphones) and mobile information terminals equipped with an imaging device have become widespread with the improvement in performance and miniaturization of imaging devices using solid-state imaging devices such as CCD image sensors or CMOS image sensors. It's getting on. In addition, there is an increasing demand for further downsizing and higher performance of imaging lenses mounted on these imaging apparatuses. Recently, there are many cases where such a portable terminal is equipped with a high-pixel / high-performance main camera and a low-pixel / small-sized sub-camera.

  As an imaging lens for main camera applications, an imaging lens having a configuration of three to five lenses has been proposed because high performance is required. On the other hand, as a sub-camera imaging lens, low-pixels of VGA or less have been common so far, so a single-lens imaging lens was the main one. In addition to the low profile (short overall length), high performance capable of dealing with high pixels such as 1.3 million pixels and 2 million pixels has been demanded. A single-lens imaging lens has been proposed.

  As the imaging lens having the two-lens configuration, imaging lenses having a positive / negative configuration as in Patent Documents 1 to 4 are known.

International Publication No. 2006/35990 Pamphlet JP 2011-28213 A JP 2010-113124 A JP 2011-145491 A

  However, the imaging lens described in Patent Document 1 has a problem that the curvature of the image side surface of the second lens is strong, the sag amount to the inflection point is large, and the moldability is deteriorated. In particular, in a lens made of a hard material such as a glass mold lens, when the moldability deteriorates, the lens surface shape variation during molding becomes large, and it becomes difficult to ensure sufficient optical performance.

  In addition, in the imaging lens described in Patent Document 2, the curvature of the image side surface of the second lens is weak, so the aberration correction is insufficient. To compensate for the insufficient aberration correction, the curvature of the object side surface of the second lens becomes strong. There is a problem that the prospective angle within the effective diameter increases and the moldability deteriorates.

  Moreover, although the imaging lens described in Patent Document 3 is an imaging lens in consideration of moldability, the curvature of the image side surface of the first lens is weak and the Petzval sum is large, so correction of field curvature is insufficient. In addition, when the total lens length is further shortened, there is a problem that performance deterioration occurs and it is difficult to cope with the increase in the number of pixels of the image sensor.

  Further, the imaging lens described in Patent Document 4 has a problem that the moldability is poor because the curvature on the second lens object side is too strong.

  The present invention has been made in view of such problems, and uses a two-lens imaging lens in which various aberrations are corrected while having better moldability than the conventional type, and the imaging lens. An object is to provide an imaging device.

Here, although it is a scale of a small imaging lens, the present invention aims at miniaturization at a level satisfying the following expression. By satisfying this range, the entire imaging apparatus can be reduced in size and weight.
L / 2Y <1.00 (7)
However,
L: Distance on the optical axis from the lens surface closest to the object side to the image-side focal point of the entire imaging lens system 2Y: diagonal length of the imaging surface of the solid-state imaging device (diagonal length of the rectangular effective pixel region of the solid-state imaging device)

Here, the image-side focal point refers to an image point when a parallel light beam parallel to the optical axis is incident on the imaging lens. When a parallel plate such as an optical low-pass filter, an infrared cut filter, or a seal glass of a solid-state image sensor package is disposed between the image-side surface of the imaging lens and the image-side focal position, the imaging lens is parallel. The flat plate portion is calculated as the above L value after the air conversion distance. More preferably, the range of the following formula is good.
L / 2Y <0.90 (7) '

The imaging lens according to claim 1 includes an aperture stop, a first lens, and a second lens in order from the object side.
The first lens is a positive meniscus lens having a convex surface on the object side and a concave surface on the image side,
The second lens is a negative lens having a paraxial concave surface facing the image side surface, and the image side surface is an imaging lens having an aspherical surface having an inflection point and a convex shape on the periphery,
An infrared cut coat on the object side surface of the second lens;
The following conditional expression is satisfied.
−1.10 <(1-n1) f / r2 <−0.20 (1)
−0.18 <(n2-1) f / r3 <0.18 (2)
−0.25 <(1-n2) f / r4 <−0.02 (3)
However,
n1: Refractive index of the first lens with respect to the d-line n2: Refractive index of the second lens with respect to the d-line r2: Radius of curvature of the side surface of the first lens (mm)
r3: radius of curvature (mm) of the side surface of the second lens object
r4: radius of curvature of the side surface of the second lens image (mm)

  By using the first lens as a positive lens and the second lens as a negative lens, a so-called telephoto type is obtained, so that the total optical length can be shortened. Furthermore, by making the shape of the first lens a meniscus lens having a convex surface facing the object side, the principal point position of the first lens with strong power can be set on the object side, so that the optical total length can be further shortened. In general, if the optical total length is shortened, the exit pupil position gets closer to the image plane.Therefore, securing telecentricity is a problem, but by placing the aperture stop closest to the object side, the exit pupil position is moved closer to the object side. By making the image side surface of the second lens an aspherical surface having an inflection point and a convex shape on the periphery (that is, the peripheral portion has a positive power), the incident angle of light on the peripheral portion of the screen is reduced. It can be reduced to ensure good telecentricity.

When the value of conditional expression (1) is less than the upper limit, the concave surface on the side surface of the first lens image can be given power, so that the Petzval sum can be reduced and the curvature of field can be corrected well. In addition, when the value of conditional expression (1) exceeds the lower limit, it is possible to prevent the occurrence of higher-order aberrations due to the concave surface becoming too strong. Furthermore, the imaging lens of the present invention desirably satisfies the following conditional expression (1 ′).
−0.90 <(1-n1) f / r2 <−0.30 (1 ′)

When the value of conditional expression (2) is lower than the upper limit or higher than the lower limit, the curvature of the object side surface of the second lens is weakened, so the expected angle of the optical surface is reduced and the moldability is improved. Furthermore, the imaging lens of the present invention desirably satisfies the following conditional expression (2 ′).
−0.15 <(n2-1) f / r3 <0.15 (2 ′)

When the value of conditional expression (3) is below the upper limit, the power of the image side surface of the second lens is increased, so that the Petzval sum is reduced and the curvature of field can be corrected well. Moreover, since the concave surface on the side surface of the second lens image is weakened when the value of conditional expression (3) exceeds the lower limit, the amount of sag up to the inflection point leading to the peripheral positive power can be suppressed to a small value. Can maintain good moldability. Furthermore, the imaging lens of the present invention desirably satisfies the following conditional expression (3 ′).
−0.20 <(1-n2) f / r4 <−0.05 (3 ′)

The imaging lens described in claim 2 is characterized in that, in the invention described in claim 1, the following conditional expression is satisfied.
-10.0 <(SAG3 / f) × 1000 <0 (4)
However,
SAG3: Sag amount at 70% of the effective diameter of the second lens object side surface

  By suppressing the sag amount on the side surface of the second lens object so as to satisfy the expression (4), the optical surface can be made a gentle surface, so that good moldability can be maintained. Here, the “effective diameter” refers to the position through which the outermost light beam of the light beam formed at the highest image height passes.

  By providing the optical surface with an IR cut function, a separate member having an infrared cut function such as an IR cut filter can be omitted, leading to cost reduction. When IR cut coating is applied to the optical surface, it is known that there is a difference in film thickness between the central portion and the peripheral portion of the lens because the lens has a curvature. In particular, since the surface satisfying the formulas (2) and (4) has a small surface angle, it is possible to suppress a film thickness variation that occurs when an IR cut coat is used as an optical surface. The shift of the wavelength characteristic to the short wavelength side can be minimized.

The imaging lens described in claim 3 is characterized in that, in the invention described in claim 1 or 2 , the following conditional expression is satisfied.
0.30 <d3 / f <0.60 (5)
However,
d3: Axial thickness (mm) of the second lens

When the value of conditional expression (5) is below the upper limit, the thickness of the second lens does not become too thick, and the optical total length can be shortened. Further, when the value of conditional expression (5) exceeds the lower limit, the thickness of the second lens is not reduced too much, and the edge thickness can be secured even if the peripheral portion of the image side surface has a sag toward the object side. Therefore, the moldability can be kept good. Furthermore, the imaging lens of the present invention desirably satisfies the following conditional expression (5 ′).
0.35 <d3 / f <0.50 (5 ')

The imaging lens of Claim 4 satisfies the following conditional expressions in the invention of any one of Claims 1-3 .
-20.0 <f2 / f1 <-5.0 (6)
However,
f1: Focal length (mm) of the first lens
f2: Focal length (mm) of the second lens

Conditional expression (6) is a conditional expression representing the ratio of the power of the first lens and the second lens. When the value of conditional expression (6) is below the upper limit, the power of the first lens is sufficiently strong with respect to the power of the second lens, so that the total optical length can be kept small. In addition, since the value of conditional expression (6) exceeds the lower limit, the second lens has a certain amount of power with respect to the power of the first lens, so the Petzval sum can be reduced and the field curvature is corrected well. can do. In addition, since the principal point of the entire system can be moved toward the object side, the optical total length can be further shortened.
Furthermore, the imaging lens of the present invention desirably satisfies the following conditional expression (6 ′).
−17.0 <f2 / f1 <−8.0 (6 ′)

An imaging lens according to a fifth aspect is the invention according to any one of the first to fourth aspects, wherein the second lens is made of glass. The second lens satisfying the expressions (2) and (3) is easy to mold and has excellent moldability when the material is glass. Further, in a lens made of a hard material such as a glass mold lens, when the moldability is deteriorated, the lens surface shape variation at the time of molding becomes large, and it becomes difficult to ensure sufficient optical performance.

An imaging lens according to a sixth aspect is the invention according to any one of the first to fourth aspects, wherein the second lens is made of resin. The second lens satisfying the expressions (2) and (3) can ensure a highly accurate surface shape even when contracted during molding.

An imaging apparatus according to a seventh aspect includes the imaging lens according to any one of the first to sixth aspects and a solid-state imaging element, and satisfies the following expression.
L / 2Y <1.00 (7)
However,
L: Distance on the optical axis from the lens surface closest to the object side to the image-side focal point of the entire imaging lens system 2Y: diagonal length of the imaging surface of the solid-state imaging device (diagonal length of the rectangular effective pixel region of the solid-state imaging device)

An imaging device according to an eighth aspect of the invention is characterized in that, in the invention according to the seventh aspect , the following expression is satisfied.
L / 2Y <0.90 (7 ')

  According to the present invention, it is possible to provide an imaging lens having a two-lens configuration in which various aberrations are corrected while having better moldability and the like than the conventional type, and an imaging apparatus using the imaging lens.

It is a perspective view of imaging device LU concerning this embodiment. It is sectional drawing which cut | disconnected the structure of FIG. 1 by the arrow II-II line, and was seen in the arrow direction. FIGS. 2A and 2B are diagrams showing a mobile phone T, in which FIG. 1A is a view of the folded mobile phone opened and viewed from the inside, and FIG. 2B is a view of the folded mobile phone opened and viewed from the outside. 1 is a cross-sectional view of an imaging lens according to Example 1. FIG. FIG. 6 is an aberration diagram of spherical aberration (a), astigmatism (b), and distortion (c) of the imaging lens according to Example 1; 6 is a cross-sectional view of an imaging lens according to Example 2. FIG. FIG. 6 is an aberration diagram of spherical aberration (a), astigmatism (b), and distortion (c) of the imaging lens according to Example 2; 6 is a cross-sectional view of an imaging lens according to Example 3. FIG. FIG. 6 is an aberration diagram of spherical aberration (a), astigmatism (b), and distortion aberration (c) of the imaging lens according to Example 3; 6 is a cross-sectional view of an imaging lens according to Example 4. FIG. FIG. 6 is an aberration diagram of spherical aberration (a), astigmatism (b), and distortion aberration (c) of the imaging lens according to Example 4; 6 is a cross-sectional view of an imaging lens according to Example 5. FIG. FIG. 10 is an aberration diagram of spherical aberration (a), astigmatism (b), and distortion aberration (c) of the imaging lens according to Example 5; 6 is a cross-sectional view of an imaging lens according to Example 6. FIG. FIG. 10 is an aberration diagram of spherical aberration (a), astigmatism (b), and distortion (c) of the imaging lens according to Example 6; 10 is a cross-sectional view of an imaging lens according to Example 7. FIG. FIG. 10 is an aberration diagram of spherical aberration (a), astigmatism (b), and distortion (c) of the imaging lens according to Example 7;

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an imaging apparatus LU according to the present embodiment, and FIG. 2 is a cross-sectional view of the configuration of FIG. 1 taken along line II-II and viewed in the direction of the arrow. As shown in FIG. 2, the imaging device LU is a CMOS type image sensor IM as a solid-state imaging device having a photoelectric conversion unit IMa, and imaging that causes the photoelectric conversion unit (light receiving surface) IMa of the image sensor IM to capture a subject image. A lens LN and an external connection terminal (electrode) (not shown) for transmitting and receiving the electrical signal are provided, and these are integrally formed.

The imaging lens LN is composed of a glass or resin-made first lens L1 and a glass or resin-made second lens L2 in order from the object side (upper side in FIG. 2). When the lens is made of glass, it can be formed by a glass mold or a droplet method. The first lens L1 is a positive meniscus lens having a convex surface on the object side and a concave surface on the image side. The second lens L2 is a negative lens having a paraxial concave surface on the image side surface, and the image side surface has an inflection point. The periphery includes an aspheric surface having a convex shape, and the following conditional expression is satisfied.
−1.10 <(1-n1) f / r2 <−0.20 (1)
−0.18 <(n2-1) f / r3 <0.18 (2)
−0.25 <(1-n2) f / r4 <−0.05 (3)
However,
n1: Refractive index of the first lens L1 with respect to the d-line n2: Refractive index with respect to the d-line of the second lens L2 r2: Radius of curvature of the first lens image side surface (mm)
r3: radius of curvature of the second lens object side surface (mm)
r4: radius of curvature of the second lens image side surface (mm)
f: Focal length of the entire system (mm)

  In the image sensor IM, a photoelectric conversion unit IMa as a light receiving unit in which pixels (photoelectric conversion elements) are two-dimensionally arranged is formed in the center of a plane on the light receiving side, and signal processing (not shown) is performed. Connected to the circuit. 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. A number of pads (not shown) are arranged near the outer edge of the light receiving side plane of the image sensor IM, and are connected to the image sensor IM via wires (not shown). The image sensor IM converts a signal charge from the photoelectric conversion unit IMa into an image signal such as a digital YUV signal and outputs the image signal to a predetermined circuit via a wire (not shown). 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 solid-state imaging device is not limited to the CMOS image sensor, and other devices such as a CCD may be used.

  The image sensor IM is connected to an external circuit (for example, a control circuit included in a host device of a portable terminal mounted with an imaging device) via an external connection terminal, and a voltage or a clock for driving the image sensor IM from the external circuit. It is possible to receive a signal and to output a digital YUV signal to an external circuit.

  The upper part of the image sensor IM is sealed with a cover glass CG. A parallel plate-shaped IR cut filter F is provided above the cover glass CG (object side) with a spacer SP3 interposed therebetween, and a second lens is disposed above the cover glass CG at a predetermined distance with a spacer SP2 interposed therebetween. The flange portion of L2 (outside of the lens portion) is fixed, and further above that, the flange portion (outside of the lens portion) of the first lens L1 is fixed via a spacer SP1.

  The outer sides of these lenses L1 and L2 are covered with a housing BX, and the lower surface of the upper flange BXa of the housing BX is supported in contact with the upper surface of the flange portion (outside of the lens portion) of the first lens L1. The lower end of the housing BX is in contact with the cover glass CG. An opening formed in the upper flange BXa of the housing BX constitutes a diaphragm S.

  Next, a mobile phone as an example of a mobile terminal equipped with an imaging device will be described with reference to the external view of FIG. 3A is a view of the folded mobile phone opened from the inside and FIG. 3B is a view of the folded mobile phone opened from the outside.

  3A and 3B, the mobile phone T includes an upper casing 71 as a case having display screens D1 and D2 and a lower casing 72 having an operation button B via a hinge 73. It is connected. In the present embodiment, the main imaging device MC for photographing a landscape or the like is provided on the surface side of the upper housing 71, and the imaging device LU including the above-described wide-angle imaging lens LN is the upper housing 71. And provided on the display screen D1.

  As shown in FIG. 3A, the imaging lens LN can capture an image of the upper body of the user who holds the mobile phone T with his / her hand, with the imaging device LU facing the imaging device LU. By transmitting the image signal to the mobile phone of the other party that is communicating and displaying the image of this user, a so-called videophone can be realized by making a normal call. The mobile phone T 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. The meaning of each symbol in the embodiment is as follows.
FL: Focal length of the entire imaging lens (mm)
BF: Back focus (mm) (however, the distance from the final optical surface excluding the parallel plate to the paraxial image plane when the parallel plate is the air conversion length)
Fno: F number w: Half angle of view (°)
Ymax: half length (mm) of the diagonal length of the imaging surface of the solid-state imaging device
TL: Distance (mm) on the optical axis from the lens surface closest to the object side to the image-side focal point of the entire imaging lens system (however, “image-side focal point” means that parallel rays parallel to the optical axis are incident on the imaging lens. (The image point at this time is obtained with the parallel plate as the air conversion length.)
r: radius of curvature of refractive surface (mm)
d: Distance between shaft upper surfaces (mm)
nd: Refractive index of lens material at d-line at room temperature vd: Abbe number of lens material STO: Aperture stop

  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 aspherical coefficient R: reference radius of curvature K: conic constant.

In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is represented using E (for example, 2.5e−002). The surface number of the lens data was given in order with the object side of the first lens as one surface. In addition, the unit of the numerical value showing the length described in an Example shall be mm.

Example 1
Table 1 shows lens data in Example 1. 4 is a sectional view of the lens of Example 1. FIG. The imaging lens according to the first exemplary embodiment includes, in order from the object side, an aperture stop S, a first lens L1, and a second lens L2 in order from the object side. The first lens L1 has a convex surface on the object side and a concave surface on the image side. It is a positive meniscus lens, and the second lens L2 is a negative lens having a paraxial concave surface directed to the image side surface, and the image side surface has an aspheric surface having an inflection point and a convex shape in the periphery. Note that F is an infrared cut filter, CG is a cover glass, and IM is a solid-state image sensor.

[Table 1]
Reference Wave Length = 587.56 nm
unit: mm

NUM. Rd nd vd eff.diameter
OBJ INFINITY 350.0000
1 INFINITY 0.0500 0.840
STO INFINITY -0.0850 0.840
3 * 0.8376 0.6530 1.58313 59.44 0.904
4 * 1.5995 0.4070 0.943
5 * 1e + 018 0.9620 1.58313 59.44 1.248
6 * 12.5380 0.1000 2.334
7 INFINITY 0.1750 1.52310 54.49 3.400
8 INFINITY 0.1690 3.400
9 INFINITY 0.4000 1.52550 62.19 3.400
IMG INFINITY 0.0563

Aspheric coefficient
3: K = -4.42830e + 000, A3 = 1.95700e-002, A4 = 9.65840e-001, A6 = -8.98080e-001, A8 = -2.17300e + 001, A10 = 3.89000e + 002, A12 =- 2.98010e + 003, A14 = 1.12680e + 004, A16 = -1.69290e + 004
4: K = -5.00000e + 001, A3 = 4.60780e-001, A4 = -4.30670e-001, A6 = 9.84810e + 000, A8 = -1.02650e + 002, A10 = 8.50080e + 002, A12 =- 4.59480e + 003, A14 = 1.43470e + 004, A16 = -1.87400e + 004
5: K = 0.00000e + 000, A4 = -4.74040e-001, A6 = 1.18080e + 000, A8 = -1.32070e + 001, A10 = 5.38720e + 001, A12 = -9.71240e + 001, A14 = 1.83010 e + 002, A16 = -1.01490e + 003, A18 = 2.50480e + 003, A20 = -1.91630e + 003
6: K = 0.00000e + 000, A4 = -9.02160e-002, A6 = -1.31520e-001, A8 = 2.57910e-001, A10 = -3.88240e-001, A12 = 2.37370e-001, A14 = 6.04190 e-002, A16 = -1.63310e-001, A18 = 7.72210e-002, A20 = -1.18490e-002

FL 2.3599
Fno 2.8224
w 64.3227
Ymax 1.5400
BF 0.694
TL 2.715

Elem Surfs Focal Length Diameter
1 3-11 2.359893 3.3685

Elem Surfs Focal Length Diameter
1 3- 4 2.291940 0.9600
2 5--6 -21.501209 2.4360

  FIG. 5 is an aberration diagram of Example 1 (spherical aberration (a), astigmatism (b), distortion (c)). Here, in the spherical aberration diagram, the solid line represents the spherical aberration amount with respect to the d line and the dotted line, respectively, and in the astigmatism diagram, the solid line represents the sagittal surface and the dotted line represents the meridional surface (hereinafter the same).

(Example 2)
Table 2 shows lens data in Example 2. 6 is a sectional view of the lens of Example 2. FIG. The imaging lens of Example 2 includes an aperture stop S, a first lens L1, and a second lens L2 in order from the object side, and from the object side. The first lens L1 has a convex surface on the object side and a concave surface on the image side. It is a positive meniscus lens, and the second lens L2 is a negative lens having a paraxial concave surface directed to the image side surface, and the image side surface has an aspheric surface having an inflection point and a convex shape in the periphery. Note that F is an infrared cut filter, CG is a cover glass, and IM is a solid-state image sensor.

[Table 2]
Reference Wave Length = 587.56 nm
unit: mm

NUM. Rd nd vd eff.diameter
OBJ INFINITY 350.0000
1 INFINITY 0.0500 0.840
STO INFINITY -0.0682 0.840
3 * 0.9004 0.6899 1.58313 59.44 0.911
4 * 1.7114 0.4692 0.981
5 * 8.0460 0.9004 1.58313 59.44 1.344
6 * 5.7540 0.1000 2.331
7 INFINITY 0.1750 1.52310 54.49 3.400
8 INFINITY 0.1690 3.400
9 INFINITY 0.4000 1.52550 62.19 3.400
IMG INFINITY 0.0924

Aspheric coefficient
3: K = -4.40583e + 000, A3 = -3.52063e-003, A4 = 8.87648e-001, A6 = -1.37562e + 000, A8 = -2.11593e + 001, A10 = 4.25059e + 002, A12 = -3.19571e + 003, A14 = 1.12751e + 004, A16 = -1.53899e + 004
4: K = -5.00000e + 001, A3 = 3.97337e-001, A4 = -4.98522e-001, A6 = 1.03872e + 001, A8 = -1.15793e + 002, A10 = 9.34071e + 002, A12 =- 4.60672e + 003, A14 = 1.23904e + 004, A16 = -1.36840e + 004
5: K = 0.00000e + 000, A4 = -5.09306e-001, A6 = 1.86433e + 000, A8 = -1.36358e + 001, A10 = 4.81356e + 001, A12 = -1.00943e + 002, A14 = 2.40224 e + 002, A16 = -7.55447e + 002, A18 = 1.34373e + 003, A20 = -8.85488e + 002
6: K = 0.00000e + 000, A4 = -1.12968e-001, A6 = -1.26251e-001, A8 = 2.82773e-001, A10 = -3.93303e-001, A12 = 2.24028e-001, A14 = 5.85290 e-002, A16 = -1.58629e-001, A18 = 8.29624e-002, A20 = -1.52528e-002

FL 2.4197
Fno 2.8224
w 62.9875
Ymax 1.5400
BF 0.730
TL 2.789

Elem Surfs Focal Length Diameter
1 3-11 2.419650 3.3201

Elem Surfs Focal Length Diameter
1 3- 4 2.480770 1.0038
2 5--6 -40.501402 2.4472

  FIG. 7 is an aberration diagram of Example 2 (spherical aberration (a), astigmatism (b), distortion (c)).

(Example 3)
Table 3 shows lens data in Example 3. FIG. 8 is a sectional view of the lens of Example 3. The imaging lens according to the third exemplary embodiment includes an aperture stop S, a first lens L1, and a second lens L2 in order from the object side. The first lens L1 has a convex surface on the object side and a concave surface on the image side. It is a positive meniscus lens, and the second lens L2 is a negative lens having a paraxial concave surface directed to the image side surface, and the image side surface has an aspheric surface having an inflection point and a convex shape in the periphery. Note that F is an infrared cut filter, CG is a cover glass, and IM is a solid-state image sensor.

[Table 3]
Reference Wave Length = 587.56 nm
unit: mm

NUM. Rd nd vd eff.diameter
OBJ INFINITY 1000.0000
1 INFINITY 0.0500 0.840
STO INFINITY -0.0623 0.840
3 * 0.9126 0.6779 1.48700 70.19 0.914
4 * 3.8590 0.5897 1.016
5 * -21.4067 1.0663 1.83400 37.19 1.340
6 * 8.6587 0.1000 2.447
7 INFINITY 0.1750 1.52310 54.49 3.400
8 INFINITY 0.1690 3.400
9 INFINITY 0.4000 1.52550 62.19 3.400
IMG INFINITY 0.0541

Aspheric coefficient
3: K = -6.01260e + 000, A3 = 3.75767e-002, A4 = 9.55063e-001, A6 = -1.88262e + 000, A8 = -2.24516e + 001, A10 = 4.54566e + 002, A12 =- 3.18006e + 003, A14 = 9.91073e + 003, A16 = -1.11738e + 004
4: K = 1.26415e + 001, A3 = 4.22193e-001, A4 = -1.62799e + 000, A6 = 1.29438e + 001, A8 = -1.15022e + 002, A10 = 9.16295e + 002, A12 = -4.67268 e + 003, A14 = 1.25006e + 004, A16 = -1.30901e + 004
5: K = 0.00000e + 000, A4 = -2.82274e-001, A6 = 9.87052e-001, A8 = -1.21176e + 001, A10 = 5.00541e + 001, A12 = -1.02408e + 002, A14 = 2.13102 e + 002, A16 = -8.12319e + 002, A18 = 1.77837e + 003, A20 = -1.38317e + 003
6: K = 0.00000e + 000, A4 = -5.42322e-002, A6 = -1.62605e-001, A8 = 3.10050e-001, A10 = -3.83069e-001, A12 = 2.15983e-001, A14 = 5.90651 e-002, A16 = -1.58014e-001, A18 = 8.26739e-002, A20 = -1.46841e-002

FL 2.5371
Fno 2.8224
w 60.9171
Ymax 1.5400
BF 0.694
TL 3.028

Elem Surfs Focal Length Diameter
1 3-11 2.537109 3.3215

Elem Surfs Focal Length Diameter
1 3- 4 2.282481 1.0321
2 5- 6 -7.274781 2.5797

  FIG. 9 is an aberration diagram of Example 3 (spherical aberration (a), astigmatism (b), distortion (c)).

Example 4
Table 4 shows lens data in Example 4. FIG. 10 is a sectional view of the lens of Example 4. The imaging lens according to the fourth exemplary embodiment includes an aperture stop S, a first lens L1, and a second lens L2 in order from the object side, and has a convex surface on the object side and a concave surface on the image side. It is a positive meniscus lens, and the second lens L2 is a negative lens having a paraxial concave surface directed to the image side surface, and the image side surface has an aspheric surface having an inflection point and a convex shape in the periphery. Note that F is an infrared cut filter, CG is a cover glass, and IM is a solid-state image sensor.

[Table 4]
Reference Wave Length = 587.56 nm
unit: mm

NUM. Rd nd vd eff.diameter
OBJ INFINITY 1000.0000
1 INFINITY 0.0500 0.898
STO INFINITY -0.1200 0.898
3 * 0.8183 0.6304 1.58313 59.39 0.932
4 * 1.4096 0.5085 0.926
5 * -44.2023 0.9173 1.58313 59.39 1.299
6 * 9.6803 0.1000 2.308
7 INFINITY 0.1750 1.52310 54.49 3.400
8 INFINITY 0.1690 3.400
9 INFINITY 0.3500 1.47140 65.19 3.400
IMG INFINITY 0.1085

Aspheric coefficient
3: K = -3.15541e + 000, A3 = -3.56669e-002, A4 = 9.24268e-001, A6 = -1.05369e-001, A8 = -3.30585e + 001, A10 = 4.60558e + 002, A12 = -3.00381e + 003, A14 = 9.82347e + 003, A16 = -1.28446e + 004
4: K = 6.90028e + 000, A3 = 2.93943e-001, A4 = -1.57193e + 000, A6 = 1.67272e + 001, A8 = -1.44248e + 002, A10 = 8.94175e + 002, A12 = -4.18454 e + 003, A14 = 1.34391e + 004, A16 = -2.09593e + 004
5: K = 0.00000e + 000, A4 = -5.35224e-001, A6 = 1.53473e + 000, A8 = -1.18000e + 001, A10 = 4.37271e + 001, A12 = -1.05196e + 002, A14 = 3.34103 e + 002, A16 = -1.20857e + 003, A18 = 2.26001e + 003, A20 = -1.52940e + 003
6: K = 0.00000e + 000, A4 = -1.27106e-001, A6 = -1.02122e-001, A8 = 2.51530e-001, A10 = -3.87909e-001, A12 = 2.31039e-001, A14 = 6.36030 e-002, A16 = -1.65851e-001, A18 = 8.24530e-002, A20 = -1.40219e-002

FL 2.5407
Fno 2.8224
w 60.8935
Ymax 1.5400
BF 0.720
TL 2.776

Elem Surfs Focal Length Diameter
1 3-11 2.540692 4.3097

Elem Surfs Focal Length Diameter
1 3- 4 2.401863 0.9700
2 5-6 -13.533350 2.5958

  FIG. 11 is an aberration diagram of Example 4 (spherical aberration (a), astigmatism (b), distortion (c)).

(Example 5)
Table 5 shows lens data in Example 5. 12 is a sectional view of the lens of Example 5. FIG. The imaging lens according to the fifth exemplary embodiment includes an aperture stop S, a first lens L1, and a second lens L2 in order from the object side, and has a convex surface on the object side and a concave surface on the image side. It is a positive meniscus lens, and the second lens L2 is a negative lens having a paraxial concave surface directed to the image side surface, and the image side surface has an aspheric surface having an inflection point and a convex shape in the periphery. In addition, CG is a cover glass and IM is a solid-state image sensor. In this embodiment, an IR cut coat is applied to the object side surface of the second lens L2.

[Table 5]
Reference Wave Length = 587.56 nm
unit: mm

NUM. Rd nd vd eff.diameter
OBJ INFINITY 1000.0000
1 INFINITY 0.0500 0.820
STO INFINITY -0.0227 0.820
3 * 0.9797 0.6220 1.72900 52.69 0.959
4 * 1.6103 0.3949 0.958
5 * 9.1068 1.1790 1.58313 59.39 1.244
6 * 7.5041 0.1000 2.507
7 INFINITY 0.3500 1.47140 65.19 3.400
IMG INFINITY 0.2631

Aspheric coefficient
3: K = -8.16625e + 000, A3 = 3.18129e-002, A4 = 9.89771e-001, A6 = -5.88553e-001, A8 = -3.76841e + 001, A10 = 4.99253e + 002, A12 =- 3.04725e + 003, A14 = 9.22448e + 003, A16 = -1.10219e + 004
4: K = 4.33221e + 000, A3 = 3.63077e-001, A4 = -1.67171e + 000, A6 = 1.58862e + 001, A8 = -1.35829e + 002, A10 = 9.18381e + 002, A12 = -4.32723 e + 003, A14 = 1.19693e + 004, A16 = -1.38134e + 004
5: K = 0.00000e + 000, A4 = -4.49680e-001, A6 = 9.33256e-001, A8 = -7.59496e + 000, A10 = 3.81113e + 001, A12 = -1.56340e + 002, A14 = 4.54470 e + 002, A16 = -7.88247e + 002, A18 = 5.54498e + 002, A20 = -2.58002e + 001
6: K = 0.00000e + 000, A4 = -8.15697e-002, A6 = -7.84948e-002, A8 = 2.35133e-001, A10 = -3.93798e-001, A12 = 2.37718e-001, A14 = 7.46519 e-002, A16 = -1.71513e-001, A18 = 8.12837e-002, A20 = -1.30862e-002

FL 2.3215
Fno 2.8224
w 65.4864
Ymax 1.5400
BF 0.592
TL 2.788

Elem Surfs Focal Length Diameter
1 3- 9 2.321550 3.3701

Elem Surfs Focal Length Diameter
1 3- 4 2.423962 0.9833
2 5-6 -100.308185 2.6834

  FIG. 13 is an aberration diagram of Example 5 (spherical aberration (a), astigmatism (b), distortion (c)).

(Example 6)
Table 6 shows lens data in Example 6. FIG. 14 is a sectional view of the lens of Example 6. The imaging lens of Example 6 includes an aperture stop S, a first lens L1, and a second lens L2 in order from the object side, and the first lens L1 has a convex surface on the object side and a concave surface on the image side. It is a positive meniscus lens, and the second lens L2 is a negative lens having a paraxial concave surface directed to the image side surface, and the image side surface has an aspheric surface having an inflection point and a convex shape in the periphery. Note that F is an infrared cut filter, CG is a cover glass, and IM is a solid-state image sensor.

[Table 6]
Reference Wave Length = 587.56 nm
unit: mm

NUM. Rd nd vd eff.diameter
OBJ INFINITY 1000.0000
STO INFINITY 0.0500 0.814
2 INFINITY -0.1122 0.808
3 * 0.7666 0.5583 1.58313 59.44 0.817
4 * 1.4482 0.4740 0.854
5 * -8.0747 0.8525 1.58313 59.44 1.190
6 * 22.8580 0.0560 2.264
7 INFINITY 0.1450 1.52550 54.99 3.000
8 INFINITY 0.0500 3.100
9 INFINITY 0.5000 1.47140 65.19 3.200
IMG INFINITY 0.1174

Aspheric coefficient
3: K = -2.47242e + 000, A3 = -2.03904e-002, A4 = 5.28641e-001, A5 = 2.54642e + 000, A6 = -8.21916e + 000, A8 = 3.04775e + 001, A10 =- 4.41460e + 001, A12 = -2.28918e + 002, A14 = 8.29246e + 002, A16 = -3.23533e + 002
4: K = -3.43564e-001, A3 = 1.96346e-002, A4 = 2.34363e-001, A5 = 1.90841e + 000, A6 = -6.24281e + 000, A8 = 4.77867e + 001, A10 = -1.42714 e + 002, A12 = -1.22119e + 003, A14 = 1.24465e + 004, A16 = -2.93322e + 004
5: K = 0.00000e + 000, A3 = 1.63283e-001, A4 = -7.76179e-001, A6 = -3.60913e-001, A8 = 6.84326e + 000, A10 = -4.15614e + 001, A12 = 8.54161 e + 001, A14 = -1.47110e + 001, A16 = -1.74300e + 002
6: K = 0.00000e + 000, A4 = 7.94924e-002, A6 = -7.06609e-001, A8 = 9.79988e-001, A10 = -3.12305e-001, A12 = -6.37242e-001, A14 = 5.03041 e-001, A16 = 1.24628e-001, A18 = -2.27376e-001, A20 = 5.74678e-002

FL 2.3694
Fno 2.8200
w 64.2796
Ymax 1.5420
BF 0.645
TL 2.530

Elem Surfs Focal Length Diameter
1 3-11 2.369447 3.5000

Elem Surfs Focal Length Diameter
1 3- 4 2.145 640 0.8537
2 5- 6 -10.129665 2.4000

  FIG. 15 is an aberration diagram of Example 6 (spherical aberration (a), astigmatism (b), distortion (c)).

(Example 7)
Table 7 shows lens data in Example 7. FIG. 16 is a sectional view of the lens of Example 7. The imaging lens of Example 7 includes an aperture stop S, a first lens L1, and a second lens L2 in order from the object side, in order from the object side, and the first lens L1 has a convex surface on the object side and a concave surface on the image side. It is a positive meniscus lens, and the second lens L2 is a negative lens having a paraxial concave surface directed to the image side surface, and the image side surface has an aspheric surface having an inflection point and a convex shape in the periphery. Note that F is an infrared cut filter, CG is a cover glass, and IM is a solid-state image sensor.

[Table 7]
Reference Wave Length = 587.56 nm
unit: mm

NUM. Rd nd vd eff.diameter
OBJ INFINITY 1000.0000
1 INFINITY 0.0500 0.831
STO INFINITY -0.0537 0.831
3 * 1.0204 0.6343 1.58313 59.39 0.924
4 * 2.7741 0.5599 1.038
5 * 9.6828 0.9844 1.71200 31.09 1.385
6 * 6.9382 0.1000 2.554
7 INFINITY 0.1750 1.52310 54.49 3.400
8 INFINITY 0.1690 3.400
9 INFINITY 0.4000 1.52550 62.19 3.400
IMG INFINITY 0.0844


Aspheric coefficient
3: K = -7.95071e + 000, A3 = 2.35363e-002, A4 = 9.82407e-001, A6 = -2.35928e + 000, A8 = -2.33433e + 001, A10 = 4.65419e + 002, A12 =- 3.19416e + 003, A14 = 1.01163e + 004, A16 = -1.22571e + 004
4: K = 1.10170e + 001, A3 = 3.78654e-001, A4 = -1.54800e + 000, A6 = 1.26252e + 001, A8 = -1.18094e + 002, A10 = 9.22635e + 002, A12 = -4.63530 e + 003, A14 = 1.24582e + 004, A16 = -1.34381e + 004
5: K = 0.00000e + 000, A4 = -2.59479e-001, A6 = 8.63308e-001, A8 = -1.18218e + 001, A10 = 5.00452e + 001, A12 = -1.03338e + 002, A14 = 2.11221 e + 002, A16 = -7.81989e + 002, A18 = 1.72624e + 003, A20 = -1.38433e + 003
6: K = 0.00000e + 000, A4 = -3.32183e-002, A6 = -1.98003e-001, A8 = 3.20956e-001, A10 = -3.80584e-001, A12 = 2.13360e-001, A14 = 5.92626 e-002, A16 = -1.57226e-001, A18 = 8.27200e-002, A20 = -1.50977e-002

FL 2.3803
Fno 2.8224
w 63.6944
Ymax 1.5400
BF 0.723
TL 2.902

Elem Surfs Focal Length Diameter
1 3-11 2.380264 3.3332

Elem Surfs Focal Length Diameter
1 3- 4 2.442743 1.0382
2 5--6 -40.404709 2.5543

  FIG. 17 is an aberration diagram of Example 7 (spherical aberration (a), astigmatism (b), distortion (c)).

  Table 8 summarizes the values of the examples corresponding to the respective conditional expressions.

  The present invention is not limited to the embodiments described in the specification, and includes other embodiments and modifications for those skilled in the art from the embodiments and technical ideas described in the present specification. it is obvious. The description and examples are for illustrative purposes only, and the scope of the invention is indicated by the following claims.

B Operation buttons D1 and D2 Display screen F IR cut filter L1 First lens L2 Second lens L3 Third lens LN Imaging lens LU Imaging device CG Cover glass S Aperture stop IM Image sensor IMa Photoelectric conversion unit T Mobile phone

Claims (8)

It consists of an aperture stop, first lens, and second lens in order from the object side.
The first lens is a positive meniscus lens having a convex surface on the object side and a concave surface on the image side,
The second lens is a negative lens having a paraxial concave surface facing the image side surface, and the image side surface is an imaging lens having an aspherical surface having an inflection point and a convex shape on the periphery,
An infrared cut coat on the object side surface of the second lens;
An imaging lens satisfying the following conditional expression:
−1.10 <(1-n1) f / r2 <−0.20 (1)
−0.18 <(n2-1) f / r3 <0.18 (2)
−0.25 <(1-n2) f / r4 <−0.02 (3)
However,
n1: Refractive index of the first lens with respect to the d-line n2: Refractive index of the second lens with respect to the d-line r2: Radius of curvature of the side surface of the first lens (mm)
r3: radius of curvature (mm) of the side surface of the second lens object
r4: radius of curvature of the side surface of the second lens image (mm)
f: Focal length of the entire system (mm) The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
-10.0 <(SAG3 / f) × 1000 <0 (4)
However,
SAG3: Sag amount at 70% of the effective diameter of the second lens object side surface The imaging lens according to claim 1 or 2, characterized by satisfying the following conditional expression.
0.30 <d3 / f <0.60 (5)
However,
d3: Axial thickness (mm) of the second lens The imaging lens according to any one of claims 1 to 3, characterized by satisfying the following conditional expression.
-20.0 <f2 / f1 <-5.0 (6)
However,
f1: Focal length (mm) of the first lens
f2: Focal length (mm) of the second lens The second lens The imaging lens according to any one of claims 1 to 4, characterized in that is made of glass. The second lens The imaging lens according to any one of claims 1 to 4, characterized in that is made of resin. An imaging lens according to any one of claims 1 to 6 and a solid-state imaging device, an imaging device and satisfies the following expression.
L / 2Y <1.00 (7)
However,
L: Distance on the optical axis from the lens surface closest to the object side to the image-side focal point of the entire imaging lens system 2Y: diagonal length of the imaging surface of the solid-state imaging device (diagonal length of the rectangular effective pixel region of the solid-state imaging device) The imaging apparatus according to claim 7 , wherein the following expression is satisfied.
L / 2Y <0.90 (7 ')