CN114791660A - Camera lens - Google Patents
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- CN114791660A CN114791660A CN202110909031.9A CN202110909031A CN114791660A CN 114791660 A CN114791660 A CN 114791660A CN 202110909031 A CN202110909031 A CN 202110909031A CN 114791660 A CN114791660 A CN 114791660A
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- 238000003384 imaging method Methods 0.000 claims abstract description 101
- 230000014509 gene expression Effects 0.000 claims abstract description 74
- 230000003287 optical effect Effects 0.000 claims abstract description 25
- 230000005499 meniscus Effects 0.000 claims description 22
- 239000006185 dispersion Substances 0.000 claims description 2
- 230000004075 alteration Effects 0.000 description 73
- 201000009310 astigmatism Diseases 0.000 description 56
- 206010010071 Coma Diseases 0.000 description 40
- 238000010586 diagram Methods 0.000 description 17
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
- G02B13/004—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having four lenses
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B30/00—Camera modules comprising integrated lens units and imaging units, specially adapted for being embedded in other devices, e.g. mobile phones or vehicles
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Abstract
The invention provides an imaging lens which can meet the requirement of low F value and has good optical characteristics. The imaging lens includes, in order from an object side to an image side: a first lens L1 having a positive power; a second lens L2; a third lens L3; and a fourth lens L4; the first lens is convex towards the object side in a paraxial region; the third lens L3 has a concave surface facing the image side in the paraxial region; the predetermined conditional expression is satisfied.
Description
Technical Field
The present invention relates to an imaging lens for forming an image of an object on a solid-state imaging element of a CCD sensor or a C-MOS sensor used in an imaging device.
Background
In recent years, camera functions have been widely mounted in various products such as home electric appliances, information terminal devices, and automobiles. In the future, development of a product incorporating a camera function is currently being carried out.
Imaging lenses mounted in such apparatuses are required to be small and high-resolution.
As a conventional imaging lens aimed at high performance, for example, an imaging lens of the following patent document 1 is known.
Patent document 1(JP2008-275783 a) discloses an imaging lens including, in order from an object side: a first lens having a positive refractive power and having a meniscus shape with a convex surface facing the object side; a second lens having a biconcave shape;
a diaphragm; a third lens in a biconvex shape; and a fourth lens having a negative refractive power and having a meniscus shape with a concave surface facing the object side;
the relationship between the thickness of the whole system of the image reading lens and the distance on the optical axis from the third lens to the fourth lens meets a certain condition.
Disclosure of Invention
Problems to be solved by the invention
When the F value is intended to be lowered by the lens structure described in patent document 1, it is very difficult to correct aberration in the peripheral portion, and good optical performance cannot be obtained.
The present invention has been made in view of the above problems, and an object of the present invention is to provide an imaging lens having a high resolution and capable of satisfactorily correcting aberrations while satisfying a requirement for a low F value in a balanced manner.
In the terms used in the present invention, the convex surface, the concave surface, and the flat surface of the lens surface mean shapes near the optical axis (paraxial). The optical power refers to the optical power near the optical axis (paraxial). The pole is a point on the aspheric surface other than the optical axis where the tangent plane perpendicularly intersects the optical axis. The total optical length is a distance on the optical axis from the object-side surface of the optical element located closest to the object side to the imaging surface. The optical total length and the back focal length are distances obtained by converting the thickness of an IR cut filter, a cover glass, or the like disposed between the imaging lens and the imaging plane into air.
Means for solving the problems
An imaging lens according to the present invention includes, in order from an object side to an image side: a first lens having a positive power and having a convex surface facing the object side in a paraxial region; a second lens; a third lens having a concave surface facing the image side in a paraxial region; and a fourth lens.
In the imaging lens having the above configuration, the first lens has a positive refractive power, thereby achieving a low back.
In addition, by having the convex surface facing the object side in the paraxial region, spherical aberration, coma, astigmatism, curvature of field, and distortion are suppressed.
In addition, astigmatism, curvature of field, and distortion are corrected well by the image side surface of the third lens with the concave surface facing the image side in the paraxial region.
In the imaging lens of the first configuration, the first configuration has, for each refractive power, in order from the object side toward the image side: a positive first lens, a negative second lens, a positive third lens, and a negative fourth lens.
In the imaging lens of the second configuration, the second configuration has, in order from the object side toward the image side: a positive first lens, a positive second lens, a negative third lens, and a positive fourth lens.
In the imaging lens of the first configuration, the first lens is preferably biconvex in the paraxial region. The first lens is biconvex in the paraxial region and has positive focal power on both surfaces, thereby realizing low back and suppressing spherical aberration, coma, astigmatism, curvature of field and distortion.
In the imaging lens having the first configuration, the second lens is preferably biconcave in the paraxial region. In addition, chromatic aberration, coma, astigmatism, curvature of field, and distortion are corrected well by the second lens in a biconcave shape in the paraxial region.
In the imaging lens having the first configuration, the third lens preferably has a meniscus shape with a concave surface facing the image side in the paraxial region. Spherical aberration, coma, astigmatism, curvature of field, and distortion are corrected well by the third lens taking a meniscus shape with the concave surface facing the image side in the paraxial region.
In the imaging lens having the first configuration, the fourth lens preferably has a meniscus shape with a convex surface facing the image side in the paraxial region. Chromatic aberration, coma, astigmatism, curvature of field, and distortion are corrected well by the fourth lens taking a meniscus shape with the convex surface facing the image side in the paraxial region.
In the imaging lens having the first configuration, that is, the configuration in which the refractive power is arranged in order from the object side, positive, negative, positive, and negative, it is preferable that the shape of each lens is a biconvex shape, a biconcave shape, a meniscus shape with the concave surface facing the image side, and a meniscus shape with the convex surface facing the image side.
In the imaging lens having the second configuration, it is preferable that the first lens has a meniscus shape with a convex surface facing the object side in the paraxial region. Spherical aberration, coma, astigmatism, curvature of field, and distortion are suppressed by the first lens taking a meniscus shape with a convex surface facing the object side in the paraxial region. In addition, by orienting the concave surface to the image side in the paraxial region, spherical aberration, coma, and astigmatism can be corrected well.
In the imaging lens having the second configuration, the second lens is preferably biconvex in the paraxial region. The second lens is biconvex in the paraxial region and has positive focal power on both surfaces, thereby realizing low back and well correcting spherical aberration, coma, astigmatism, curvature of field and distortion.
In the imaging lens of the second configuration, the third lens is preferably biconcave in the paraxial region. Chromatic aberration, coma, astigmatism, curvature of field, and distortion are corrected well by the third lens taking a biconcave shape in the paraxial region.
In the imaging lens having the second configuration, the fourth lens preferably has a meniscus shape with a concave surface facing the image side in the paraxial region. In addition, by the fourth lens taking a meniscus shape with the concave surface facing the image side in the paraxial region, coma, astigmatism, curvature of field, and distortion are corrected well.
In the imaging lens having the second configuration, that is, the configuration in which the refractive power is arranged in order of positive, negative, and positive from the object side, it is preferable that the shape of each lens is a meniscus shape in which a convex surface faces the object side, a biconvex shape, a biconcave shape, and a meniscus shape in which a concave surface faces the image side in order from the object side in the paraxial region.
In the imaging lenses of the first and second configurations, it is preferable that each lens surface is formed to be an aspherical surface. By forming each lens surface to be aspherical, each aberration is corrected well.
With the imaging lens of the present invention having the above configuration, a low F value with an F value of 4.0 or less is realized.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (1) is satisfied,
(1)13＜νd4＜34
wherein,
ν d 4: the fourth lens has an abbe number with respect to the d-line.
By satisfying the range of the conditional expression (1), chromatic aberration can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (2) is satisfied,
(2) 0.3＜νd3/νd4＜2.0
wherein,
ν d 3: the third lens has an abbe number with respect to the d-line,
ν d 4: the fourth lens has an Abbe number with respect to the d-line.
By satisfying the range of the conditional expression (2), chromatic aberration can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (3) is satisfied,
(3) 0.25＜|r2/r3|＜0.85
wherein,
r 2: a paraxial radius of curvature of an image-side surface of the first lens,
r 3: a paraxial radius of curvature of an object-side surface of the second lens.
By satisfying the range of conditional expression (3), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (4) is satisfied,
(4) 0.85＜|f4|/f＜3.85
f 4: the focal length of the fourth lens element is,
f: the focal length of the whole system of the camera lens.
By satisfying the range of conditional expression (4), coma, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (5) is satisfied,
(5) 0.15＜|r2|/f＜0.55
wherein,
r 2: a paraxial radius of curvature of an image-side surface of the first lens,
f: the focal length of the whole system of the camera lens.
By satisfying the range of conditional expression (5), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (6) is satisfied,
(6) 0.2＜|r3|/f＜1.2
wherein,
r 3: the paraxial radius of curvature of the object-side surface of the second lens,
f: the focal length of the whole system of the camera lens.
By satisfying the range of conditional expression (6), astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (7) is satisfied,
(7) 0.5＜r6/|f3|＜6.0
wherein,
r 6: the paraxial radius of curvature of the image-side surface of the third lens,
f 3: the focal length of the third lens.
By satisfying the range of conditional expression (7), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (8) is satisfied,
(8) 9＜D3/|f3|)×100＜43
wherein,
d3: the thickness of the third lens on the optical axis,
f 3: the focal length of the third lens.
By satisfying the range of conditional expression (8), low back can be achieved, and spherical aberration, coma, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (9) is satisfied,
(9) 0.1＜|f2|/f＜0.7
wherein,
f 2: the focal length of the second lens is such that,
f: the focal length of the whole system of the camera lens.
By satisfying the range of conditional expression (9), coma, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (10) is satisfied,
(10) 0.1＜|f3|/f＜0.8
wherein,
f 3: the focal length of the third lens is such that,
f: the focal length of the whole system of the camera lens.
By satisfying the range of conditional expression (10), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (11) is satisfied,
(11) 13＜νd3＜34
wherein,
ν d 3: the third lens has an abbe number with respect to the d-line.
By satisfying the range of the conditional expression (11), chromatic aberration can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (12) is satisfied,
(12) 0.1＜r1/f＜0.4
wherein,
r 1: the paraxial radius of curvature of the object-side surface of the first lens,
f: the focal length of the whole system of the camera lens.
By satisfying the range of conditional expression (12), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (13) is satisfied,
(13) 0.3＜r1/|r2|＜1.5
wherein,
r 1: the paraxial radius of curvature of the object-side surface of the first lens,
r 2: a paraxial radius of curvature of an image-side surface of the first lens.
By satisfying the range of conditional expression (13), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (14) is satisfied,
(14) 0.2＜|r2/r8|＜1.8
wherein,
r 2: a paraxial radius of curvature of an image-side surface of the first lens,
r 8: paraxial radius of curvature of the image-side surface of the fourth lens.
By satisfying the range of conditional expression (14), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (15) is satisfied,
(15) 0.05＜|r2/f1|＜2.00
wherein,
r 2: a paraxial radius of curvature of an image-side surface of the first lens,
f 1: the focal length of the first lens.
By satisfying the range of conditional expression (15), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expressions (16), (16)0.65 < | r3/r7| < 3.70 be satisfied
Wherein,
r 3: the paraxial radius of curvature of the object-side surface of the second lens,
r 7: paraxial radius of curvature of the object-side surface of the fourth lens.
By satisfying the range of conditional expression (16), coma, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (17) is satisfied,
(17) 0.25＜|r5|/f＜0.80
wherein,
r 5: the paraxial radius of curvature of the object-side surface of the third lens,
f: the focal length of the whole system of the camera lens.
By satisfying the range of conditional expression (17), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (18) is satisfied,
(18) 0.5＜|r5|/T3＜9.0
wherein,
r 5: the paraxial radius of curvature of the object-side surface of the third lens,
t3: and the distance on the optical axis from the image side surface of the third lens to the object side surface of the fourth lens.
By satisfying the range of the conditional expression (18), lowering of the back is achieved, and spherical aberration, coma, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (19) is satisfied,
(19) 0.05＜|r5|/r6＜1.60
wherein,
r 5: the paraxial radius of curvature of the object-side surface of the third lens,
r 6: paraxial radius of curvature of the image-side surface of the third lens.
By satisfying the range of conditional expression (19), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (20) is satisfied,
(20) 0.2＜|r5/f3|＜2.0
wherein,
r 5: the paraxial radius of curvature of the object-side surface of the third lens,
f 3: focal length of the third lens.
By satisfying the range of conditional expression (20), spherical aberration, coma aberration, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (21) is satisfied,
(21) 0.2＜r6/f＜3.0
wherein,
r 6: the paraxial radius of curvature of the image-side surface of the third lens,
f: the focal length of the whole system of the camera lens.
By satisfying the range of the conditional expression (21), astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (22) is satisfied,
(22) 0.1＜|r7|/f＜0.8
wherein,
r 7: the paraxial radius of curvature of the object-side surface of the fourth lens,
f: the focal length of the whole system of the camera lens.
By satisfying the range of conditional expression (22), coma, astigmatism, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (23) is satisfied,
(23) 0.2＜|r7|/(T3+bf)＜1.7
wherein,
r 7: the paraxial radius of curvature of the object-side surface of the fourth lens,
t3: the distance on the optical axis from the image side surface of the third lens to the object side surface of the fourth lens,
bf: back focal length.
By satisfying the range of conditional expression (23), the lower back can be realized, and coma aberration, astigmatism, and distortion can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (24) is satisfied,
(24) 0.1＜|r7/r8|＜1.6
wherein,
r 7: the paraxial radius of curvature of the object-side surface of the fourth lens,
r 8: paraxial radius of curvature of the image-side surface of the fourth lens.
By satisfying the range of conditional expression (24), coma, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above configuration, it is preferable that the following conditional expression (25) is satisfied,
(25) 6＜(D2/|f2|)×100＜61
wherein,
d2: the thickness of the second lens on the optical axis,
f 2: focal length of the second lens.
By satisfying the range of conditional expression (25), the lower back can be realized, and coma, astigmatism, curvature of field, and distortion can be corrected well.
In the imaging lens having the above-described configuration, it is preferable that the following conditional expression (26) is satisfied,
(26) 0.05＜|f2/f4|＜0.75
wherein,
f 2: the focal length of the second lens is such that,
f 4: focal length of the fourth lens.
By satisfying the range of conditional expression (26), coma, astigmatism, curvature of field, and distortion can be corrected well.
The present invention can provide an imaging lens that can correct aberrations well and has high resolution.
Drawings
Fig. 1 is a diagram showing a schematic configuration of an imaging lens according to example 1 of the first embodiment of the present invention.
Fig. 2 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to example 1 of the first embodiment of the present invention.
Fig. 3 is a diagram showing a schematic configuration of an imaging lens according to example 2 of the second embodiment of the present invention.
Fig. 4 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens in example 2 of the second embodiment of the present invention.
Fig. 5 is a diagram showing a schematic configuration of an imaging lens according to example 3 of the second embodiment of the present invention.
Fig. 6 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to example 3 of the second embodiment of the present invention.
Fig. 7 is a diagram showing a schematic configuration of an imaging lens according to example 4 of the second embodiment of the present invention.
Fig. 8 is a diagram showing spherical aberration, astigmatism and distortion of the imaging lens in example 4 of the second embodiment of the present invention.
Fig. 9 is a diagram showing a schematic configuration of an imaging lens according to example 5 of the second embodiment of the present invention.
Fig. 10 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens in example 5 of the second embodiment of the present invention.
Fig. 11 is a diagram showing a schematic configuration of an imaging lens according to example 6 of the second embodiment of the present invention.
Fig. 12 is a diagram showing spherical aberration, astigmatism, and distortion of the imaging lens according to example 6 of the second embodiment of the present invention.
Detailed Description
Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.
Fig. 1 is a schematic configuration diagram of an imaging lens according to example 1 of the first embodiment of the present invention. Fig. 3, 5, 7, 9, and 11 are schematic configuration diagrams of imaging lenses according to examples 2 to 6 of the second embodiment of the present invention, respectively.
As shown in the schematic configuration diagram, the imaging lens of the present invention includes, in order from an object side to an image side: a first lens L1 having a positive power; a second lens L2; a third lens L3; and a fourth lens L4, the first lens L1 being convex toward the object side in the paraxial region, and the third lens L3 being concave toward the image side in the paraxial region.
A filter IR such as an infrared cut filter or a cover glass is disposed between the fourth lens L4 and the imaging surface IMG (i.e., the imaging surface of the image pickup device). In addition, the filter IR can be omitted.
Since the aperture stop ST is disposed on the object side of the first lens L1, it is easy to correct each aberration and to suppress the angle at which high-image-height light rays enter the imaging element.
[ first embodiment ]
Hereinafter, a first embodiment according to the present invention will be described in detail with reference to fig. 1.
The first lens L1 has a positive power and is biconvex in the paraxial region. Therefore, the lower back is achieved by the positive power of both surfaces, and spherical aberration, coma, astigmatism, curvature of field, and distortion are suppressed.
The second lens L2 has a negative power and is biconcave in the paraxial region. Therefore, chromatic aberration, coma, astigmatism, curvature of field, and distortion are corrected well.
The third lens L3 has a positive power and has a meniscus shape with a concave surface facing the image side in the paraxial region. Therefore, spherical aberration, coma, astigmatism, curvature of field, and distortion are corrected well.
The fourth lens L4 has a negative refractive power and has a meniscus shape with a convex surface facing the image side in the paraxial region. Therefore, chromatic aberration, coma, astigmatism, curvature of field, and distortion are corrected well.
[ second embodiment ]
A second embodiment according to the present invention will be described in detail below with reference to fig. 3.
The first lens L1 has a positive power and has a meniscus shape with a convex surface facing the object side in the paraxial region. Thus, spherical aberration, coma, astigmatism, curvature of field, and distortion are suppressed. In addition, by orienting the concave surface to the image side in the paraxial region, spherical aberration, coma, and astigmatism can be corrected well.
The second lens L2 has a positive power and is biconvex in the paraxial region. Therefore, spherical aberration, coma, astigmatism, curvature of field, and distortion are corrected well.
The third lens L3 has a negative power and is biconcave in the paraxial region. Therefore, chromatic aberration, coma, astigmatism, curvature of field, and distortion are corrected well.
The fourth lens L4 has a positive power and has a meniscus shape with a concave surface facing the image side in the paraxial region. Accordingly, coma, astigmatism, curvature of field, and distortion are corrected well.
In the imaging lens of the present embodiment, all of the first lens L1 to the fourth lens L4 are preferably configured by a single lens. The aspherical surface can be more used by being constituted by only a single lens. In the present embodiment, the aberrations are corrected favorably by forming all the lens surfaces to be appropriate aspherical surfaces. Further, since the number of steps can be reduced as compared with the case of using a cemented lens, the manufacturing can be performed at low cost.
In the imaging lens of the present embodiment, it is preferable that all lens surfaces are formed to be aspherical, but a spherical surface which is easy to manufacture may be used in accordance with required performance.
The imaging lens in the present embodiment satisfies the following conditional expressions (1) to (26), and exhibits a preferable effect.
(1) 13＜νd4＜34
(2) 0.3＜νd3/νd4＜2.0
(3) 0.25＜|r2/r3|＜0.85
(4) 0.85＜|f4|/f＜3.85
(5) 0.15＜|r2|/f＜0.55
(6) 0.2＜|r3|/f＜1.2
(7) 0.5＜r6/|f3|＜6.0
(8) 9＜(D3/|f3|)×100＜43
(9) 0.1＜|f2|/f＜0.7
(10) 0.1＜|f3|/f＜0.8
(11) 13＜νd3＜34
(12) 0.1＜r1/f＜0.4
(13) 0.3＜r1/|r2|＜1.5
(14) 0.2＜|r2/r8|＜1.8
(15) 0.05＜|r2/f1|＜2.00
(16) 0.65＜|r3/r7|＜3.70
(17) 0.25＜|r5|/f＜0.80
(18) 0.5＜|r5|/T3＜9.0
(19) 0.05＜|r5|/r6＜1.60
(20) 0.2＜|r5/f3|＜2.0
(21) 0.2＜r6/f＜3.0
(22) 0.1＜|r7|/f＜0.8
(23) 0.2＜|r7|/(T3+bf)＜1.7
(24) 0.1＜|r7/r8|＜1.6
(25) 6＜(D2/|f2|)×100＜61
(26) 0.05＜|f2/f4|＜0.75
Wherein,
ν d 3: the third lens L3 has an abbe number with respect to the d-line,
ν d 4: the dispersion coefficient of the fourth lens L4 with respect to the d-line,
d2: the thickness of the second lens L2 on the optical axis X,
d3: the thickness of the third lens L3 on the optical axis X,
t3: the distance on the optical axis X from the image side surface of the third lens L3 to the object side surface of the fourth lens L4,
bf: the back focal length of the lens is set,
f: the focal length of the whole system of the camera lens,
f 1: the focal length of the first lens L1,
f 2: the focal length of the second lens L2,
f 3: the focal length of the third lens L3,
f 4: the focal length of the fourth lens L4,
r 1: the paraxial radius of curvature of the object-side surface of the first lens L1,
r 2: the paraxial radius of curvature of the image-side surface of the first lens L1,
r 3: the paraxial radius of curvature of the object-side surface of second lens L2,
r 5: the paraxial radius of curvature of the object-side surface of the third lens L3,
r 6: the paraxial radius of curvature of the image-side surface of the third lens L3,
r 7: the paraxial radius of curvature of the object-side surface of fourth lens L4,
r 8: paraxial radius of curvature of the image-side surface of the fourth lens L4.
Further, it is not necessary to satisfy all of the conditional expressions, and it is possible to obtain the operational effects corresponding to the conditional expressions by satisfying each conditional expression individually.
In the present embodiment, the imaging lens satisfies the following conditional expressions (1a) to (26a), and exhibits a further advantageous effect.
(1a) 16＜νd4＜29
(2a) 0.6＜νd3/νd4＜1.7
(3a) 0.4＜|r2/r3|＜0.8
(4a) 1.0＜|f4|/f＜3.4
(5a) 0.25＜|r2|/f＜0.45
(6a) 0.3＜|r3|/f＜0.9
(7a) 0.9＜r6/|f3|＜4.9
(8a) 14＜(D3/|f3|)×100＜36
(9a) 0.15＜|f2|/f＜0.60
(10a) 0.2＜|f3|/f＜0.6
(11a) 16＜νd3＜29
(12a) 0.2＜r1/f＜0.3
(13a) 0.45＜r1/|r2|＜1.1
(14a) 0.25＜|r2/r8|＜1.50
(15a) 0.15＜|r2/f1|＜1.60
(16a) 1＜|r3/r7|＜3
(17a) 0.27＜|r5|/f＜0.65
(18a) 1.7＜|r5|/T3＜7.5
(19a) 0.10＜|r5|/r6＜1.35
(20a) 0.4＜|r5/f3|＜1.6
(21a) 0.3＜r6/f＜2.4
(22a) 0.2＜|r7|/f＜0.6
(23a) 0.4＜|r7|/(T3+bf)＜1.3
(24a) 0.2＜|r7/r8|＜1.3
(25a) 9＜(D2/|f2|)×100＜50
(26a) 0.1＜|f2/f4|＜0.6
The symbols of the conditional expressions are the same as those described in the preceding paragraph. The lower limit or the upper limit of the corresponding conditional expressions (1a) to (26a) may be applied to the lower limit or the upper limit of the conditional expressions (1) to (26).
In the present embodiment, the aspherical shape adopted for the aspherical surface of the lens surface is expressed by expression 1 when the axis in the optical axis direction is Z, the height in the direction orthogonal to the optical axis is H, the paraxial radius of curvature is R, the conic coefficient is k, and the aspherical coefficients are a4, a6, A8, a10, a12, a14, a16, a18, and a 20.
[ mathematical formula 1]
Next, an example of the imaging lens according to the present embodiment is shown. In each embodiment, F represents a focal length of the entire imaging lens system, Fno represents an F value, ω represents a half field pair, ih represents a maximum image height, and TTL represents a total optical length. In addition, i denotes a surface number counted from the object side, r denotes a paraxial radius of curvature, d denotes a distance (surface interval) between lens surfaces on the optical axis, Nd denotes a refractive index of a d-line (reference wavelength), and vd denotes an abbe number with respect to the d-line. Note that, the aspherical surface is indicated by an asterisk symbol attached to the back of the surface number i.
[ example 1]
The basic lens data are shown in table 1 below.
[ Table 1]
Example 1
mm
f＝18.35
Fno＝3.80
ω(°)＝7.0
ih＝2.29
TTL＝17.24
Surface data
Composing lens data
Aspheric data
The imaging lens of embodiment 1 realizes an F value of 3.80. As shown in table 7, conditional expressions (1) to (26) are satisfied.
Fig. 2 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 1. The spherical aberration diagram shows the amount of aberration for each wavelength of the F-line (486nm), d-line (588nm), and C-line (656 nm). The astigmatism diagrams show the amount of d-line aberration on sagittal image plane S (solid line) and the amount of d-line aberration on meridional image plane T (broken line), respectively (the same applies to fig. 4, 6, 8, 10, and 12). As shown in fig. 2, it is understood that each aberration is corrected well.
[ example 2]
The basic lens data are shown in table 2 below.
[ Table 2]
Example 2
mm
f＝18.35
Fno＝3.80
ω(°)＝7.0
ih＝2.29
TTL＝18.16
Surface data
Composing lens data
Aspheric data
The imaging lens of embodiment 2 realizes an F value of 3.80. As shown in table 7, conditional expressions (1) to (26) are satisfied.
Fig. 4 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to embodiment 2. As shown in fig. 4, it is understood that each aberration is corrected well.
[ example 3]
The basic lens data are shown in table 3 below.
[ Table 3]
Example 3
mm
f＝18.35
Fno＝3.80
ω(°)＝7.0
ih＝2.29
TTL＝18.02
Surface data
Composing lens data
Aspheric data
The imaging lens of embodiment 3 realizes an F value of 3.80. As shown in table 7, conditional expressions (1) to (26) are satisfied.
Fig. 6 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 3. As shown in fig. 6, it is understood that each aberration is corrected well.
[ example 4]
The basic lens data are shown in table 4 below.
[ Table 4]
Example 4
mm
f＝18.35
Fno＝3.80
ω(°)＝7.0
ih＝2.29
TTL＝18.05
Surface data
Composing lens data
Aspheric data
The imaging lens of embodiment 4 realizes an F value of 3.80. As shown in table 7, conditional expressions (1) to (26) are satisfied.
Fig. 8 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to embodiment 4. As shown in fig. 8, it is understood that each aberration is corrected well.
[ example 5]
The basic lens data are shown in table 5 below.
[ Table 5]
Example 5
mm
f＝18.35
Fno＝3.80
ω(°)＝7.0
ih＝2.29
TTL＝17.81
Surface data
Composing lens data
Aspheric data
The imaging lens of embodiment 5 realizes an F value of 3.80. As shown in table 7, conditional expressions (1) to (26) are satisfied.
Fig. 10 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 5. As shown in fig. 10, it is understood that each aberration is corrected well.
[ example 6]
The basic lens data are shown in table 6 below.
[ Table 6]
Example 6
mm
f＝18.35
Fno＝3.80
ω(°)＝7.0
ih＝2.29
TTL＝18.07
Surface data
Composing lens data
Aspherical data
The imaging lens of the embodiment realizes an F value of 3.80. As shown in table 7, conditional expressions (1) to (26) are satisfied.
Fig. 12 shows spherical aberration (mm), astigmatism (mm), and distortion (%) of the imaging lens according to example 6. As shown in fig. 12, it is understood that each aberration is corrected well.
Table 7 shows values of conditional expressions (1) to (26) according to examples 1 to 6.
[ Table 7]
Industrial applicability
When the imaging lens according to the present invention is applied to a product having a camera function, the imaging lens contributes to a low F value of the camera and can achieve high performance of the camera.
Description of the reference numerals
ST aperture diaphragm,
L1 first lens,
L2 second lens,
L3 third lens,
L4 fourth lens,
An IR filter,
And (5) an IMG image pickup surface.
Claims (7)
1. An imaging lens includes, in order from an object side to an image side:
a first lens having a positive focal power;
a second lens;
a third lens; and
a fourth lens;
the first lens is convex towards the object side in a paraxial region; the concave surface of the third lens faces to the image side in the paraxial region; satisfies the following conditional expressions (1), (2), (3) and (4),
(1)13＜νd4＜34
(2)0.3＜νd3/νd4＜2.0
(3)0.25＜|r2/r3|＜0.85
(4)0.85＜|f4|/f＜3.85
wherein,
ν d 4: the dispersion coefficient of the fourth lens L4 with respect to the d-line,
ν d 3: the third lens L3 has an abbe number with respect to the d-line,
r 2: a paraxial radius of curvature of an image-side surface of the first lens,
r 3: the paraxial radius of curvature of the object-side surface of the second lens,
f 4: the focal length of the fourth lens is such that,
f: the focal length of the whole system of the camera lens.
2. The imaging lens according to claim 1, characterized in that the following conditional expression (5) is satisfied:
(5)0.15＜|r2|/f＜0.55
wherein,
r 2: a paraxial radius of curvature of an image-side surface of the first lens,
f: the focal length of the whole system of the camera lens.
3. The imaging lens according to claim 1, wherein the following conditional expression (6) is satisfied:
(6)0.2＜|r3|/f＜1.2
wherein,
r 3: the paraxial radius of curvature of the object-side surface of the second lens,
f: the focal length of the whole system of the camera lens.
4. The imaging lens according to claim 1, wherein the following conditional expression (8) is satisfied:
(8)9＜(D3/|f3|)×100＜43
wherein,
d3: the thickness of the third lens on the optical axis,
f 3: the focal length of the third lens.
5. The imaging lens according to claim 1, characterized in that the following conditional expression (9) is satisfied:
(9)0.1＜|f2|/f＜0.7
wherein,
f 2: the focal length of the second lens is such that,
f: the focal length of the whole system of the camera lens.
6. The imaging lens according to claim 1,
a first lens having a biconvex shape in a paraxial region;
a second lens having a negative focal power and having a biconcave shape in a paraxial region;
a third lens having a positive refractive power and having a meniscus shape with a concave surface facing the image side in the paraxial region; and
and a fourth lens having a negative refractive power and having a meniscus shape with a convex surface facing the image side in the paraxial region.
7. The imaging lens according to claim 1,
a first lens having a meniscus shape with a convex surface facing the object side in a paraxial region;
a second lens having a positive focal power and taking a biconvex shape in a paraxial region;
a third lens having negative refractive power and having a biconcave shape with a concave surface facing the image side in the paraxial region; and
and a fourth lens having a positive refractive power and having a meniscus shape with a concave surface facing the image side in the paraxial region.
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| JPH09113803A (en) * | 1995-10-20 | 1997-05-02 | Asahi Optical Co Ltd | Reading lens |
| JPH1184229A (en) * | 1997-09-02 | 1999-03-26 | Canon Inc | Single focus lens |
| JP2010181554A (en) * | 2009-02-04 | 2010-08-19 | Fujinon Corp | Imaging lens and imaging apparatus |
| KR20110072343A (en) * | 2009-12-22 | 2011-06-29 | 삼성전기주식회사 | Optical system for night |
| JP2013250586A (en) * | 2013-09-19 | 2013-12-12 | Ricoh Co Ltd | Imaging lens and imaging apparatus |
| CN208621825U (en) * | 2018-07-25 | 2019-03-19 | 中山市美景光学信息有限公司 | A kind of telescope optical system for taking pictures |
| CN216310377U (en) * | 2021-01-25 | 2022-04-15 | 东京晨美光学电子株式会社 | Camera lens |
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- 2021-08-09 CN CN202121851507.XU patent/CN216310377U/en active Active
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Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09113803A (en) * | 1995-10-20 | 1997-05-02 | Asahi Optical Co Ltd | Reading lens |
| JPH1184229A (en) * | 1997-09-02 | 1999-03-26 | Canon Inc | Single focus lens |
| JP2010181554A (en) * | 2009-02-04 | 2010-08-19 | Fujinon Corp | Imaging lens and imaging apparatus |
| KR20110072343A (en) * | 2009-12-22 | 2011-06-29 | 삼성전기주식회사 | Optical system for night |
| JP2013250586A (en) * | 2013-09-19 | 2013-12-12 | Ricoh Co Ltd | Imaging lens and imaging apparatus |
| CN208621825U (en) * | 2018-07-25 | 2019-03-19 | 中山市美景光学信息有限公司 | A kind of telescope optical system for taking pictures |
| CN216310377U (en) * | 2021-01-25 | 2022-04-15 | 东京晨美光学电子株式会社 | Camera lens |
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