Camera lens

Abstract

The present invention provides a camera lens, which can meet the requirements of low F value and has good optical characteristics. The camera lens comprises, from the object side to the image side, a first lens L1 having positive optical power; a second lens L2; ​​a third lens L3; and a fourth lens L4; the first lens has a convex surface facing the object side in the paraxial zone; the third lens L3 has a concave surface facing the image side in the paraxial zone; and a predetermined conditional formula is satisfied.

Description

Technical Field

[0001] The present invention relates to an imaging lens for forming an image of a subject on a solid-state imaging element of a CCD sensor or a C-MOS sensor used in an imaging device. Background Art

[0002] In recent years, camera functions have been widely installed in various products such as home appliances, information terminals, and automobiles. It is expected that the development of products incorporating camera functions will continue in the future.

[0003] The imaging lens installed in such equipment needs to be compact and have high resolution performance.

[0004] As an imaging lens that aims at improving performance in the related art, for example, an imaging lens disclosed in Patent Document 1 below is known.

[0005] Patent document 1 (JP2008-275783) discloses a camera lens, which includes, from the object side, a first lens having positive optical power and a meniscus shape with a convex surface facing the object side; a second lens having a biconcave shape;

[0006] an aperture; a third lens having a biconvex shape; and a fourth lens having a negative optical power and a meniscus shape with a concave surface facing the object side;

[0007] The relationship between the thickness of the entire image reading lens system and the distance on the optical axis from the third lens to the fourth lens satisfies a certain condition. Summary of the invention

[0008] Problem that the invention aims to solve

[0009] When attempting to lower the F value using the lens structure described in Patent Document 1, it is extremely difficult to correct aberrations in the peripheral portion, and good optical performance cannot be obtained.

[0010] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an imaging lens having a high resolution that satisfies the demand for a lower F-number in a balanced manner and that satisfies various aberrations with good correction.

[0011] Furthermore, regarding the terms used in the present invention, the convex surface, concave surface, and plane surface of the lens surface refer to the shape near the optical axis (paraxial). The optical power refers to the optical power near the optical axis (paraxial). The pole refers to the point on the aspheric surface other than the optical axis where the tangent plane intersects the optical axis perpendicularly. The total optical length refers to the distance on the optical axis from the object side of the optical element located closest to the object side to the imaging surface. In addition, the total optical length and the back focal length are distances obtained by converting the thickness of the IR cutoff filter or protective glass disposed between the imaging lens and the imaging surface into air.

[0012] Means used to solve problems

[0013] The camera lens of the present invention comprises, from the object side to the image side, a first lens having positive optical power and a convex surface facing the object side in the paraxial zone; a second lens; a third lens having a concave surface facing the image side in the paraxial zone; and a fourth lens.

[0014] The imaging lens of the above structure can achieve low profile by virtue of the first lens having positive refractive power.

[0015] In addition, by making the convex surface toward the object side in the paraxial region, spherical aberration, coma, astigmatism, field curvature and distortion are suppressed.

[0016] In addition, since the image side surface of the third lens element is concave toward the image side in the paraxial region, astigmatism, field curvature and distortion are well corrected.

[0017] In the imaging lens of the first structure described above, regarding each optical power, the first structure has, 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.

[0018] In addition, in the above-mentioned second structure of the imaging lens, regarding each optical power, the second structure 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.

[0019] In the camera lens of the first structure, the first lens is preferably biconvex in the paraxial region. The first lens is biconvex in the paraxial region and has positive optical power on both sides to achieve low profile and suppress spherical aberration, coma, astigmatism, field curvature and distortion.

[0020] In the imaging lens of the first structure, the second lens is preferably biconcave in the paraxial region. In addition, chromatic aberration, coma, astigmatism, field curvature and distortion are well corrected by the second lens being biconcave in the paraxial region.

[0021] In the above-mentioned first structure of the camera lens, the third lens is preferably in a meniscus shape with a concave surface facing the image side in the paraxial region. By the third lens being in a meniscus shape with a concave surface facing the image side in the paraxial region, spherical aberration, coma, astigmatism, field curvature and distortion are well corrected.

[0022] In the above-mentioned first structure of the imaging lens, the fourth lens is preferably in a meniscus shape with a convex surface facing the image side in the paraxial region. By the fourth lens being in a meniscus shape with a convex surface facing the image side in the paraxial region, chromatic aberration, coma, astigmatism, field curvature and distortion are well corrected.

[0023] In addition, in the camera lens of the first structure described above, that is, the optical focal length is arranged in the order of positive, negative, positive, and negative from the object side, the shape of each lens is preferably 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 paraxial zone from the object side.

[0024] In the above-mentioned second structure of the imaging lens, it is preferred that the first lens has a meniscus shape with a convex surface facing the object side in the paraxial region. By having the first lens have a meniscus shape with a convex surface facing the object side in the paraxial region, spherical aberration, coma, astigmatism, field curvature and distortion are suppressed. In addition, by having a concave surface facing the image side in the paraxial region, spherical aberration, coma and astigmatism can be well corrected.

[0025] In the above-mentioned second structure of the camera lens, it is preferred that the second lens is biconvex in the paraxial region. By making the second lens biconvex in the paraxial region and having positive optical power on both sides, low-profile lens can be achieved, and spherical aberration, coma, astigmatism, field curvature and distortion can be well corrected.

[0026] In the above-mentioned second imaging lens, the third lens is preferably biconcave in the paraxial region. The third lens is biconcave in the paraxial region, so that chromatic aberration, coma, astigmatism, field curvature and distortion can be well corrected.

[0027] In the above-mentioned second structure of the imaging lens, the fourth lens is preferably in a meniscus shape with a concave surface facing the image side in the paraxial region. In addition, the fourth lens is in a meniscus shape with a concave surface facing the image side in the paraxial region, so that coma, astigmatism, field curvature and distortion are well corrected.

[0028] In addition, in the above-mentioned second structure of the camera lens, that is, the optical focal length is arranged in the structure of positive, positive, negative, and positive in sequence from the object side, the shape of each lens is preferably a meniscus shape with the convex surface facing the object side, a biconvex shape, a biconcave shape, and a meniscus shape with the concave surface facing the image side in the paraxial zone in sequence from the object side.

[0029] In the imaging lenses of the first and second structures, it is preferable that each lens surface is formed as an aspherical surface. By forming each lens surface as an aspherical surface, various aberrations can be corrected well.

[0030] By adopting the above-mentioned structure, the imaging lens of the present invention can realize a low F value of 4.0 or less.

[0031] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (1) is satisfied:

[0032] (1) 13<νd4<34

[0033] in,

[0034] νd4: The dispersion coefficient of the fourth lens with respect to the d-line.

[0035] By satisfying the range of conditional expression (1), chromatic aberration can be corrected well.

[0036] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (2) is satisfied:

[0037] (2) 0.3<νd3 / νd4<2.0

[0038] in,

[0039] νd3: dispersion coefficient of the third lens relative to the d-line,

[0040] νd4: The dispersion coefficient of the fourth lens with respect to the d-line.

[0041] By satisfying the range of conditional expression (2), chromatic aberration can be corrected well.

[0042] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (3) is satisfied:

[0043] (3) 0.25<|r2 / r3|<0.85

[0044] in,

[0045] r2: paraxial radius of curvature of the image side of the first lens,

[0046] r3: paraxial radius of curvature of the object side of the second lens.

[0047] By satisfying the range of conditional expression (3), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0048] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (4) is satisfied:

[0049] (4) 0.85<|f4| / f<3.85

[0050] f4: focal length of the fourth lens,

[0051] f: Focal length of the entire camera lens system.

[0052] By satisfying the range of conditional expression (4), coma, astigmatism, field curvature, and distortion can be corrected well.

[0053] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (5) is satisfied:

[0054] (5) 0.15<|r2| / f<0.55

[0055] in,

[0056] r2: paraxial radius of curvature of the image side of the first lens,

[0057] f: Focal length of the entire camera lens system.

[0058] By satisfying the range of conditional expression (5), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0059] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (6) is satisfied:

[0060] (6) 0.2<|r3| / f<1.2

[0061] in,

[0062] r3: the paraxial radius of curvature of the object side of the second lens,

[0063] f: Focal length of the entire camera lens system.

[0064] By satisfying the range of conditional expression (6), astigmatism, field curvature, and distortion can be corrected well.

[0065] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (7) is satisfied:

[0066] (7) 0.5<r6 / |f3|<6.0

[0067] in,

[0068] r6: paraxial curvature radius of the image side of the third lens,

[0069] f3: focal length of the third lens.

[0070] By satisfying the range of conditional expression (7), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0071] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (8) is satisfied:

[0072] (8) 9<D3 / |f3|)×100<43

[0073] in,

[0074] D3: The thickness of the third lens on the optical axis,

[0075] f3: focal length of the third lens.

[0076] By satisfying the range of conditional expression (8), a low profile can be achieved, and spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0077] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (9) is satisfied:

[0078] (9) 0.1<|f2| / f<0.7

[0079] in,

[0080] f2: focal length of the second lens,

[0081] f: Focal length of the entire camera lens system.

[0082] By satisfying the range of conditional expression (9), coma, astigmatism, field curvature, and distortion can be corrected well.

[0083] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (10) is satisfied:

[0084] (10) 0.1<|f3| / f<0.8

[0085] in,

[0086] f3: focal length of the third lens,

[0087] f: Focal length of the entire camera lens system.

[0088] By satisfying the range of conditional expression (10), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0089] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (11) is satisfied:

[0090] (11) 13<νd3<34

[0091] in,

[0092] νd3: The dispersion coefficient of the third lens with respect to the d-line.

[0093] By satisfying the range of conditional expression (11), chromatic aberration can be corrected well.

[0094] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (12) is satisfied:

[0095] (12) 0.1<r1 / f<0.4

[0096] in,

[0097] r1: paraxial radius of curvature of the object side of the first lens,

[0098] f: Focal length of the entire camera lens system.

[0099] By satisfying the range of conditional expression (12), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0100] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (13) is satisfied:

[0101] (13) 0.3<r1 / |r2|<1.5

[0102] in,

[0103] r1: paraxial radius of curvature of the object side of the first lens,

[0104] r2: paraxial radius of curvature of the image-side surface of the first lens.

[0105] By satisfying the range of conditional expression (13), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0106] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (14) is satisfied:

[0107] (14) 0.2<|r2 / r8|<1.8

[0108] in,

[0109] r2: paraxial radius of curvature of the image side of the first lens,

[0110] r8: paraxial radius of curvature of the image-side surface of the fourth lens.

[0111] By satisfying the range of conditional expression (14), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0112] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (15) is satisfied:

[0113] (15) 0.05<|r2 / f1|<2.00

[0114] in,

[0115] r2: paraxial radius of curvature of the image side of the first lens,

[0116] f1: focal length of the first lens.

[0117] By satisfying the range of conditional expression (15), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0118] In the imaging lens of the above configuration, it is preferable that the following conditional expression (16) is satisfied: (16) 0.65 < |r3 / r7| < 3.70

[0119] in,

[0120] r3: the paraxial radius of curvature of the object side of the second lens,

[0121] r7: paraxial radius of curvature of the object side of the fourth lens.

[0122] By satisfying the range of conditional expression (16), coma, astigmatism, field curvature, and distortion can be corrected well.

[0123] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (17) is satisfied:

[0124] (17) 0.25<|r5| / f<0.80

[0125] in,

[0126] r5: the paraxial radius of curvature of the object side of the third lens,

[0127] f: Focal length of the entire camera lens system.

[0128] By satisfying the range of conditional expression (17), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0129] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (18) is satisfied:

[0130] (18) 0.5<|r5| / T3<9.0

[0131] in,

[0132] r5: the paraxial radius of curvature of the object side of the third lens,

[0133] 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.

[0134] By satisfying the range of conditional expression (18), low profile can be achieved, and spherical aberration, coma, astigmatism, field curvature and distortion can be corrected well.

[0135] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (19) is satisfied:

[0136] (19) 0.05<|r5| / r6<1.60

[0137] in,

[0138] r5: the paraxial radius of curvature of the object side of the third lens,

[0139] r6: paraxial radius of curvature of the image-side surface of the third lens.

[0140] By satisfying the range of conditional expression (19), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0141] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (20) is satisfied:

[0142] (20) 0.2<|r5 / f3|<2.0

[0143] in,

[0144] r5: the paraxial radius of curvature of the object side of the third lens,

[0145] f3: focal length of the third lens.

[0146] By satisfying the range of conditional expression (20), spherical aberration, coma, astigmatism, field curvature, and distortion can be corrected well.

[0147] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (21) is satisfied:

[0148] (21) 0.2<r6 / f<3.0

[0149] in,

[0150] r6: paraxial curvature radius of the image side of the third lens,

[0151] f: Focal length of the entire camera lens system.

[0152] By satisfying the range of conditional expression (21), astigmatism, field curvature, and distortion can be corrected well.

[0153] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (22) is satisfied:

[0154] (22) 0.1<|r7| / f<0.8

[0155] in,

[0156] r7: the paraxial radius of curvature of the object side of the fourth lens,

[0157] f: Focal length of the entire camera lens system.

[0158] By satisfying the range of conditional expression (22), coma, astigmatism, and distortion can be corrected well.

[0159] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (23) is satisfied:

[0160] (23) 0.2<|r7| / (T3+bf)<1.7

[0161] in,

[0162] r7: the paraxial radius of curvature of the object side of the fourth lens,

[0163] T3: The distance on the optical axis from the image side of the third lens to the object side of the fourth lens.

[0164] bf: back focal length.

[0165] By satisfying the range of conditional expression (23), a low profile can be achieved, and coma, astigmatism, and distortion can be corrected well.

[0166] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (24) is satisfied:

[0167] (24) 0.1<|r7 / r8|<1.6

[0168] in,

[0169] r7: the paraxial radius of curvature of the object side of the fourth lens,

[0170] r8: paraxial radius of curvature of the image-side surface of the fourth lens.

[0171] By satisfying the range of conditional expression (24), coma, astigmatism, field curvature, and distortion can be corrected well.

[0172] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (25) is satisfied:

[0173] (25) 6<(D2 / |f2|)×100<61

[0174] in,

[0175] D2: The thickness of the second lens on the optical axis,

[0176] f2: Focal length of the second lens.

[0177] By satisfying the range of conditional expression (25), a low profile can be achieved, and coma, astigmatism, field curvature, and distortion can be corrected well.

[0178] In addition, in the imaging lens of the above structure, it is preferable that the following conditional expression (26) is satisfied:

[0179] (26) 0.05<|f2 / f4|<0.75

[0180] in,

[0181] f2: focal length of the second lens,

[0182] f4: Focal length of the fourth lens.

[0183] By satisfying the range of conditional expression (26), coma, astigmatism, field curvature, and distortion can be corrected well.

[0184] According to the present invention, it is possible to obtain an imaging lens which can satisfactorily correct various aberrations and has high resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0185] Figure 1 It is a diagram showing a schematic configuration of an imaging lens according to Example 1 of the first embodiment of the present invention.

[0186] Figure 2 These are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 1 according to the first embodiment of the present invention.

[0187] Figure 3 It is a diagram showing a schematic structure of an imaging lens according to Example 2 of the second embodiment of the present invention.

[0188] Figure 4 These are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 2 according to the second embodiment of the present invention.

[0189] Figure 5 It is a diagram showing a schematic structure of an imaging lens according to Example 3 of the second embodiment of the present invention.

[0190] Figure 6 These are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 3 according to the second embodiment of the present invention.

[0191] Figure 7 It is a diagram showing a schematic structure of an imaging lens according to Example 4 of the second embodiment of the present invention.

[0192] Figure 8 These are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 4 according to the second embodiment of the present invention.

[0193] Fig. 9 It is a diagram showing a schematic structure of an imaging lens according to Example 5 of the second embodiment of the present invention.

[0194] Fig.10 These are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 5 according to the second embodiment of the present invention.

[0195] Fig.11 A diagram showing a schematic configuration of an imaging lens according to Example 6 of the second embodiment of the present invention.

[0196] Fig.12 These are diagrams showing spherical aberration, astigmatism, and distortion of the imaging lens of Example 6 according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0197] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0198] Figure 1 A schematic configuration diagram of an imaging lens according to Example 1 of the first embodiment of the present invention is shown. Figure 3 , Figure 5 , Figure 7 , Fig. 9 and Fig.11 Schematic diagrams of the configurations of imaging lenses according to Examples 2 to 6 of the second embodiment of the present invention are shown respectively.

[0199] As shown in the schematic structure diagram, the camera lens of the present invention includes, from the object side to the image side, a first lens L1 having positive optical focal length; a second lens L2; ​​a third lens L3; and a fourth lens L4, wherein the first lens L1 has a convex surface facing the object side in the paraxial zone, and the third lens L3 has a concave surface facing the image side in the paraxial zone.

[0200] An infrared cut filter, a protective glass or other filter IR is disposed between the fourth lens L4 and the imaging plane IMG (ie, the imaging plane of the imaging element).

[0201] The aperture stop ST is disposed on the object side of the first lens L1 , so that various aberrations can be easily corrected and the angle of a high image highlight ray incident on the imaging element can be easily suppressed.

[0202] [First embodiment]

[0203] Below, refer to Figure 1 A first embodiment of the present invention will be described in detail.

[0204] The first lens L1 has positive refractive power and is biconvex in the paraxial region. Therefore, the positive refractive power on both sides can achieve low profile and suppress spherical aberration, coma, astigmatism, field curvature and distortion.

[0205] The second lens L2 has negative power and is biconcave in the paraxial region, so chromatic aberration, coma, astigmatism, field curvature and distortion are well corrected.

[0206] The third lens L3 has positive refractive power and is in a meniscus shape with a concave surface facing the image side in the paraxial region. Therefore, spherical aberration, coma, astigmatism, field curvature and distortion are well corrected.

[0207] The fourth lens L4 has negative refractive power and is in a meniscus shape with a convex surface facing the image side in the paraxial region. Therefore, chromatic aberration, coma, astigmatism, field curvature and distortion are well corrected.

[0208] [Second Embodiment]

[0209] Below, refer to Figure 3A second embodiment of the present invention will be described in detail.

[0210] The first lens L1 has positive refractive power and is in a meniscus shape with a convex surface facing the object side in the paraxial region. Therefore, spherical aberration, coma, astigmatism, field curvature and distortion are suppressed. In addition, spherical aberration, coma and astigmatism can be well corrected by having a concave surface facing the image side in the paraxial region.

[0211] The second lens L2 has positive refractive power and is biconvex in the paraxial region, so spherical aberration, coma, astigmatism, field curvature and distortion are well corrected.

[0212] The third lens L3 has negative power and is biconcave in the paraxial region, so chromatic aberration, coma, astigmatism, field curvature and distortion are well corrected.

[0213] The fourth lens L4 has positive refractive power and has a meniscus shape with a concave surface facing the image side in the paraxial region, so coma, astigmatism, field curvature and distortion are well corrected.

[0214] In the camera lens of this embodiment, it is preferred that all lenses from the first lens L1 to the fourth lens L4 are composed of respective single lenses. The use of only single lenses allows more use of aspheric surfaces. In this embodiment, by forming all lens surfaces into appropriate aspheric surfaces, various aberrations are well corrected. In addition, compared with the case of using a cemented lens, since the man-hours can be reduced, it can be manufactured at a low cost.

[0215] In the imaging lens of the present embodiment, it is preferable that all lens surfaces are formed as aspherical surfaces, but spherical surfaces that are easy to manufacture may be adopted depending on the required performance.

[0216] In addition, the imaging lens in this embodiment satisfies the following conditional expressions (1) to (26), thereby achieving favorable effects.

[0217] (1) 13<νd4<34

[0218] (2) 0.3<νd3 / νd4<2.0

[0219] (3) 0.25<|r2 / r3|<0.85

[0220] (4) 0.85<|f4| / f<3.85

[0221] (5) 0.15<|r2| / f<0.55

[0222] (6) 0.2<|r3| / f<1.2

[0223] (7) 0.5<r6 / |f3|<6.0

[0224] (8) 9<(D3 / |f3|)×100<43

[0225] (9) 0.1<|f2| / f<0.7

[0226] (10) 0.1<|f3| / f<0.8

[0227] (11) 13<νd3<34

[0228] (12) 0.1<r1 / f<0.4

[0229] (13) 0.3<r1 / |r2|<1.5

[0230] (14) 0.2<|r2 / r8|<1.8

[0231] (15) 0.05<|r2 / f1|<2.00

[0232] (16) 0.65<|r3 / r7|<3.70

[0233] (17) 0.25<|r5| / f<0.80

[0234] (18) 0.5<|r5| / T3<9.0

[0235] (19) 0.05<|r5| / r6<1.60

[0236] (20) 0.2<|r5 / f3|<2.0

[0237] (21) 0.2<r6 / f<3.0

[0238] (22) 0.1<|r7| / f<0.8

[0239] (23) 0.2<|r7| / (T3+bf)<1.7

[0240] (24) 0.1<|r7 / r8|<1.6

[0241] (25) 6<(D2 / |f2|)×100<61

[0242] (26) 0.05<|f2 / f4|<0.75

[0243] in,

[0244] νd3: the dispersion coefficient of the third lens L3 with respect to the d-line,

[0245] νd4: dispersion coefficient of the fourth lens L4 with respect to the d-line,

[0246] D2: thickness of the second lens L2 on the optical axis X,

[0247] D3: thickness of the third lens L3 on the optical axis X,

[0248] 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,

[0249] bf: back focal length,

[0250] f: focal length of the entire camera lens system,

[0251] f1: focal length of the first lens L1,

[0252] f2: focal length of the second lens L2,

[0253] f3: focal length of the third lens L3,

[0254] f4: focal length of the fourth lens L4,

[0255] r1: the paraxial radius of curvature of the object side of the first lens L1,

[0256] r2: paraxial curvature radius of the image side surface of the first lens L1,

[0257] r3: the paraxial radius of curvature of the object side of the second lens L2,

[0258] r5: paraxial radius of curvature of the object side of the third lens L3,

[0259] r6: paraxial radius of curvature of the image side surface of the third lens L3,

[0260] r7: paraxial radius of curvature of the object side of the fourth lens L4,

[0261] r8: paraxial curvature radius of the image-side surface of the fourth lens L4.

[0262] It is not necessary to satisfy all of the above-mentioned conditional expressions, and by satisfying each conditional expression individually, the effects corresponding to each conditional expression can be obtained.

[0263] Furthermore, the imaging lens in this embodiment satisfies the following conditional expressions (1a) to (26a), thereby achieving better effects.

[0264] (1a) 16<νd4<29

[0265] (2a) 0.6<νd3 / νd4<1.7

[0266] (3a) 0.4<|r2 / r3|<0.8

[0267] <h2 style=";text-align:left;direction:ltr">(4a) 1.0 = |f4| / f = 3.4<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0268] <h2 style=";text-align:left;direction:ltr"> (5a) 0.25 = |r2| / f = 0.45<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0269] <h2 style=";text-align:left;direction:ltr"> (6a) 0.3 = |r3| / f = 0.9<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0270] <h2 style=";text-align:left;direction:ltr"> (7a) 0.9 = r6 / |f3| = 4.9<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0271] <h2 style=";text-align:left;direction:ltr"> (8a) 14 = (D3 / |f3|)×100 = 36<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0272] <h2 style=";text-align:left;direction:ltr"> (9a) 0.15 = |f2| / f = 0.60<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0273] <h2 style=";text-align:left;direction:ltr"> (10a) 0.2 = |f3| / f = 0.6<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0274] <h2 style=";text-align:left;direction:ltr"> (11a) 16<νd3<29<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0275] <h2 style=";text-align:left;direction:ltr"> (12a) 0.2<r1 / f<0.3<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0276] <h2 style=";text-align:left;direction:ltr"> (13a) 0.45 = r1 / |r2| = 1.1<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0277] <h2 style=";text-align:left;direction:ltr"> (14a) 0.25 = |r2 / r8| = 1.50<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0278] <h2 style=";text-align:left;direction:ltr"> (15a) 0.15 = |r2 / f1| = 1.60<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0279] <h2 style=";text-align:left;direction:ltr"> (16a) 1<|r3 / r7|<3<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0280] <h2 style=";text-align:left;direction:ltr"> (17a) 0.27 = |r5| / f = 0.65<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0281] <h2 style=";text-align:left;direction:ltr"> (18a) 1.7 = |r5| / T3 = 7.5<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0282] <h2 style=";text-align:left;direction:ltr"> (19a) 0.10 = |r5| / r6 = 1.35<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0283] <h2 style=";text-align:left;direction:ltr"> (20a) 0.4 = |r5 / f3| = 1.6<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0284] <h2 style=";text-align:left;direction:ltr"> (21a) 0.3<r6 / f<2.4<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0285] <h2 style=";text-align:left;direction:ltr"> (22a) 0.2 = |r7| / f = 0.6<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0286] <h2 style=";text-align:left;direction:ltr"> (23a) 0.4 = |r7| / (T3+bf) = 1.3<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0287] <h2 style=";text-align:left;direction:ltr"> (24a) 0.2 = |r7 / r8| = 1.3<h2 style=";text-align:left;direction:ltr"> <h2 style=";text-align:left;direction:ltr">

[0288] (25a) 9<(D2 / |f2|)×100<50

[0289] (26a) 0.1<|f2 / f4|<0.6

[0290] The symbols of each conditional expression are the same as those described in the previous paragraph. In addition, the lower limit value or upper limit value of the corresponding conditional expressions (1a) to (26a) can be applied to the lower limit value or upper limit value of the conditional expressions (1) to (26).

[0291] In this embodiment, the aspheric shape used on the aspheric surface of the lens surface is expressed by mathematical formula 1 when the axis in the optical axis direction is set to Z, the height in the direction perpendicular to the optical axis is set to H, the near-axis curvature radius is set to R, the cone coefficient is set to k, and the aspheric coefficient is set to A4, A6, A8, A10, A12, A14, A16, A18, and A20.

[0292] [Mathematical formula 1]

[0293]

[0294] Next, examples of the imaging lens involved in this embodiment are shown. In each example, f represents the focal length of the entire imaging lens system, Fno represents the F value, ω represents the half field of view, ih represents the maximum image height, and TTL represents the total optical length. In addition, i represents the surface number from the object side, r represents the paraxial curvature radius, d represents the distance between the lens surfaces on the optical axis (surface spacing), Nd represents the refractive index of the d-line (reference wavelength), and νd represents the dispersion coefficient relative to the d-line. In addition, for aspherical surfaces, the symbol * (asterisk) is added after the surface number i to represent it.

[0295] [Example 1]

[0296] Basic lens data are shown in Table 1 below.

[0297] [Table 1]

[0298] Example 1

[0299] Unit mm

[0300] f=18.35

[0301] Fno=3.80

[0302] ω(°)=7.0

[0303] ih=2.29

[0304] TTL=17.24

[0305] Area data

[0306]

[0307] Composition lens data

[0308]

[0309] Aspheric surface data

[0310]

[0311] The imaging lens of Example 1 achieves an F value of 3.80. As shown in Table 7, conditional expressions (1) to (26) are satisfied.

[0312] Figure 2 The spherical aberration (mm), astigmatism (mm), and distortion (%) are shown for the imaging lens of Example 1. The spherical aberration diagram shows the aberration amount for each wavelength of the F line (486nm), d line (588nm), and C line (656nm). In addition, the astigmatism diagram shows the aberration amount of the d line on the sagittal image plane S (solid line) and the aberration amount of the d line on the meridional image plane T (dashed line). Figure 4 , Figure 6 , Figure 8 , Fig.10 and Fig.12 are the same in the examples. Figure 2 As shown, it can be seen that each aberration is well corrected.

[0313] [Example 2]

[0314] Basic lens data are shown in Table 2 below.

[0315] [Table 2]

[0316] Example 2

[0317] Unit mm

[0318] f=18.35

[0319] Fno=3.80

[0320] ω(°)=7.0

[0321] ih=2.29

[0322] TTL=18.16

[0323] Area data

[0324]

[0325] Composition lens data

[0326]

[0327] Aspheric surface data

[0328]

[0329] The imaging lens of Example 2 achieves an F value of 3.80. As shown in Table 7, conditional expressions (1) to (26) are satisfied.

[0330] Figure 4 For the imaging lens of Example 2, spherical aberration (mm), astigmatism (mm), and distortion (%) are shown. Figure 4 As shown, it can be seen that each aberration is well corrected.

[0331] [Example 3]

[0332] Basic lens data are shown in Table 3 below.

[0333] [Table 3]

[0334] Example 3

[0335] Unit mm

[0336] f=18.35

[0337] Fno=3.80

[0338] ω(°)=7.0

[0339] ih=2.29

[0340] TTL=18.02

[0341] Area data

[0342]

[0343] Composition lens data

[0344]

[0345] Aspheric surface data

[0346]

[0347] The imaging lens of Example 3 achieves an F value of 3.80. As shown in Table 7, conditional expressions (1) to (26) are satisfied.

[0348] Figure 6 For the imaging lens of Example 3, spherical aberration (mm), astigmatism (mm), and distortion (%) are shown. Figure 6 As shown, it can be seen that each aberration is well corrected.

[0349] [Example 4]

[0350] Basic lens data are shown in Table 4 below.

[0351] [Table 4]

[0352] Example 4

[0353] Unit mm

[0354] f=18.35

[0355] Fno=3.80

[0356] ω(°)=7.0

[0357] ih=2.29

[0358] TTL=18.05

[0359] Area data

[0360]

[0361] Composition lens data

[0362]

[0363] Aspheric surface data

[0364]

[0365] The imaging lens of Example 4 achieves an F value of 3.80. As shown in Table 7, conditional expressions (1) to (26) are satisfied.

[0366] Figure 8 For the imaging lens of Example 4, spherical aberration (mm), astigmatism (mm), and distortion (%) are shown. Figure 8 As shown, it can be seen that each aberration is well corrected.

[0367] [Example 5]

[0368] Basic lens data are shown in Table 5 below.

[0369] [Table 5]

[0370] Example 5

[0371] Unit mm

[0372] f=18.35

[0373] Fno=3.80

[0374] ω(°)=7.0

[0375] ih=2.29

[0376] TTL=17.81

[0377] Area data

[0378]

[0379] Composition lens data

[0380]

[0381] Aspheric surface data

[0382]

[0383] The imaging lens of Example 5 achieves an F value of 3.80. As shown in Table 7, conditional expressions (1) to (26) are satisfied.

[0384] Fig.10 For the imaging lens of Example 5, spherical aberration (mm), astigmatism (mm), and distortion (%) are shown. Fig.10 As shown, it can be seen that each aberration is well corrected.

[0385] [Example 6]

[0386] Basic lens data are shown in Table 6 below.

[0387] [Table 6]

[0388] Example 6

[0389] Unit mm

[0390] f=18.35

[0391] Fno=3.80

[0392] ω(°)=7.0

[0393] ih=2.29

[0394] TTL=18.07

[0395] Area data

[0396]

[0397] Composition lens data

[0398]

[0399] Aspheric surface data

[0400]

[0401] The imaging lens of the embodiment achieves an F value of 3.80. As shown in Table 7, conditional expressions (1) to (26) are satisfied.

[0402] Fig.12For the imaging lens of Example 6, spherical aberration (mm), astigmatism (mm), and distortion (%) are shown. Fig.12 As shown, it can be seen that each aberration is well corrected.

[0403] Table 7 shows the values ​​of conditional expressions (1) to (26) according to Examples 1 to 6.

[0404] [Table 7]

[0405]

[0406] Industrial Applicability

[0407] When the imaging lens according to the present invention is applied to a product with a camera function, it can contribute to a lower F value of the camera and achieve higher performance of the camera.

[0408] Description of Reference Numerals

[0409] ST Aperture Stop,

[0410] L1 first lens,

[0411] L2 Second lens,

[0412] L3 third lens,

[0413] L4 fourth lens,

[0414] IR filter,

[0415] IMG camera surface.

Claims

1. A camera lens, characterized in that: From the object side to the image side, they include: A first lens having positive optical power; Second lens; a third lens; and The fourth lens; The convex surface of the first lens in the paraxial zone faces the object side; the concave surface of the third lens in the paraxial zone faces the image side; the following conditional equations (1), (2), (3), (4), (8) and (9) are satisfied: (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 (8)9<(D3 / |f3|)×100<43 (9)0.1<|f2| / f<0.7 in, νd4: dispersion coefficient of the fourth lens L4 with respect to the d-line, νd3: the dispersion coefficient of the third lens L3 with respect to the d-line, r2: paraxial radius of curvature of the image side of the first lens, r3: paraxial radius of curvature of the object side of the second lens, f4: focal length of the fourth lens, f: focal length of the entire camera lens system, f2: focal length of the second lens, D3: The thickness of the third lens on the optical axis, f3: focal length of the third lens.

2. The imaging lens according to claim 1, wherein: The following condition (5) is satisfied: (5)0.15＜|r2| / f＜0.55 in, r2: paraxial radius of curvature of the image side of the first lens, f: Focal length of the entire camera lens system.

3. The imaging lens according to claim 1, wherein: The following condition (6) is satisfied: (6)0.2＜|r3| / f＜1.2 in, r3: paraxial radius of curvature of the object side of the second lens, f: Focal length of the entire camera lens system.

4. The imaging lens according to claim 1, wherein: The first lens is biconvex in the paraxial region; The second lens has negative optical power and is biconcave in the paraxial region; The third lens has positive optical power and is in a meniscus shape with a concave surface facing the image side in the paraxial region; as well as The fourth lens has negative refractive power and is in a meniscus shape with a convex surface facing the image side in the paraxial region.

5. The imaging lens according to claim 1, wherein: The first lens is in the shape of a meniscus with a convex surface facing the object side in the paraxial region; The second lens has positive optical power and is biconvex in the paraxial region; The third lens has negative optical power and is biconcave in shape with a concave surface facing the image side in the paraxial region; as well as The fourth lens has positive refractive power and is in a meniscus shape with a concave surface facing the image side in the paraxial region.

Images