This application claims the priority benefit of Japanese Patent Applications Ser. No. 2018-137214 filed on Jul. 20, 2018, the entire content of which is incorporated herein by reference.
The present disclosure relates to the field of camera lenses, and more particularly, to a camera lens, which is constituted by eight lenses, is applicable to a mobile phone camera assembly, a WEB camera lens and the like using camera elements such as a high-pixel CCD and a CMOS, and meanwhile has an excellent optical characteristic, an ultra-thin appearance with total track length (TTL)/image height (IH)≤1.65, a wide angle with a field of view (hereinafter briefly referred to as 2ω) of 70° or more, and an F-number (hereinafter briefly referred to as Fno) of 1.45 or less.
In recent years, various types of camera devices using camera elements such as a CCD and a CMOS have been widely applied. With miniaturization and high performance-oriented development of these camera elements, the society has a stronger demand for a camera lens with excellent optical characteristics, an ultra-thin appearance, a wide-angle and a bright Fno.
A camera lens which is constituted by eight lenses and has a bright Fno is disclosed in the related art.
In the lens disclosed in related art, refractive powers of respective lenses from a 1st lens to an 8th lens are (positive, negative, positive, negative, positive, negative, negative, negative), (positive, negative, positive, negative, positive, positive, negative, negative), (positive, positive, negative, positive, negative, positive, negative negative), or (positive, positive, negative, positive, positive, positive, negative, negative), so Fno=1.20˜1.60 which is bright, but TTL/IH>1.90 which is not ultra-thin enough.
An embodiment of a camera lens related to the present disclosure will be described with reference to the accompanying drawing.
The 1st lens L1 has a positive refractive power, the 2nd lens L2 has a negative refractive power, the 3rd lens L3 has a negative refractive power, the 4th lens L4 has a positive refractive power, the 5th lens L5 has a negative refractive power, the 6th lens L6 has a positive refractive power, the 7th lens L7 has a positive refractive power, and the 8th lens L8 has a negative refractive power. In order to better correct an aberration problem, it is most preferable to design surfaces of the eight lenses as aspherical.
The camera lens LA is a camera lens that satisfies conditional formulas (1)-(2) below:
−0.20≤f1/f2≤−0.10 (1);
−0.20≤f1/f3≤−0.10 (2);
Where,
f1: a focal length of the 1st lens;
f2: a focal length of the 2nd lens;
f3: a focal length of the 3rd lens.
The conditional formula (1) specifies the rate of the focal length f1 of the 1st lens L1 to the focal length f2 of the 2nd lens L2. Outside a range of the conditional formula (1), it is difficult to correct an on-axis and off-axis color aberration with Fno≤1.45.
Here, it is most preferable to set a numerical range of the conditional formula (1) within a numerical range of a conditional formula (1-A) below:
−0.18≤f1/f2≤−0.15 (1-A).
The conditional formula (2) specifies the rate of the focal length f1 of the 1st lens L1 to the focal length f3 of the 3rd lens L3. Outside a range of the conditional formula (2), it is difficult to correct on-axis and off-axis color aberration with Fno≤1.45.
Here, it is most preferable to set a numerical range of the conditional formula (2) within a numerical range of a conditional formula (2-A) below:
−0.18≤f1/f3≤−0.15 (2-A).
The 2nd lens L2 has a negative refractive power, and satisfies a conditional formula (3) below:
0.80≤f2/f3≤1.20 (3);
Where,
f2: the focal length of the 2nd lens;
f3: the focal length of the 3rd lens.
The conditional formula (3) specifies the rate of the focal length f2 of the 2nd lens L2 to the focal length f3 of the 3rd lens L3. Outside a range of the conditional formula (3), it is difficult to correct on-axis and off-axis color aberration with Fno≤1.45.
Here, it is most preferable to set a numerical range of the conditional formula (3) within a numerical range of a conditional formula (3-A) below:
0.90≤f2/f3≤1.10 (3-A).
The 1st lens L1 has a positive refractive power, and satisfies a conditional formula (4) below:
1.00≤f1/f≤1.50 (4);
Where,
f: the focal length of the overall camera lens;
f1: the focal length of a 1st lens.
The conditional formula (4) specifies a positive refractive power of the 1st lens L1. Outside a range of the conditional formula (4), it is difficult to develop toward ultra-thinness and wide-angle with Fno≤1.45.
Here, it is most preferable to set a numerical range of the conditional formula (4) within a numerical range of a conditional formula (4-A) below:
1.05≤f1/f≤1.20 (4-A).
The 2nd lens L2 has a negative refractive power and satisfies a conditional formula (5) below:
−8.00≤f2/f≤−5.00 (5).
Where,
f: the focal length of the overall camera lens;
f2: a focal length of the 2nd lens.
The conditional formula (5) specifies a negative refractive power of the 2nd lens L2. Outside a range of the conditional formula (5), it is difficult to correct on-axis and off-axis color aberration with Fno≤1.45.
Here, it is most preferable to set a numerical range of the conditional formula (5) within a numerical range of a conditional formula (5-A) below:
−7.00≤f2/f≤−6.00 (5-A).
The 3rd lens L3 has a negative refractive power and satisfies a conditional formula (6) below:
−8.00≤f3/f≤−5.00 (6).
Where,
f: the focal length of the overall camera lens;
f3: the focal length of the 3rd lens.
The conditional formula (6) specifies a negative refractive power of the 3rd lens L3. Outside a range of the conditional formula (6), it is difficult to correct on-axis and off-axis color aberration with Fno≤1.45.
Here, it is most preferable to set a numerical range of the conditional formula (6) within a numerical range of a conditional formula (6-A) below:
−7.00≤f3/f≤−6.00 (6-A).
The eight lenses constituting the camera lens LA respectively satisfy the configurations and the conditional formulas as described above, which makes it possible to fabricate the camera lens having an excellent optical characteristic, an ultra-thin appearance with total track length (TTL)/image height (IH)≤1.65, a wide angle with 2ω≥70°, and an Fno with Fno≤1.45.
Hereinafter, the camera lens LA according to the present disclosure will be described with embodiments. Symbols recited in the respective embodiments are shown below. Distance, radius and center thickness are in units of mm.
f: a focal length of the overall camera lens LA;
f1: a focal length of a 1st lens L1;
f2: a focal length of a 2nd lens L2;
f3: a focal length of a 3rd lens L3;
f4: a focal length of a 4th lens L4;
f5: a focal length of a 5th lens L5;
f6: a focal length of a 6th lens L6;
f7: a focal length of a 7th lens L7;
f8: a focal length of an 8th lens L8;
Fno: F number;
2ω: field of view;
STOP: open stop;
S1: stop 1;
S2: stop 2;
S3: stop 3;
R: a curvature radius of an optical surface, and a central curvature radius in a case of a lens;
R1: a curvature radius of an object side surface of the 1st lens L1;
R2: a curvature radius of an image side surface of the 1st lens L1;
R3: a curvature radius of an object side surface of the 2nd lens L2;
R4: a curvature radius of an image side surface of the 2nd lens L2;
R5: a curvature radius of an object side surface of the 3rd lens L3;
R6: a curvature radius of an image side surface of the 3rd lens L3;
R7: a curvature radius of an object side surface of the 4th lens L4;
R8: a curvature radius of an image side surface of the 4th lens L4;
R9: a curvature radius of an object side surface of the 5th lens L5;
R10: a curvature radius of an image side surface of the 5th lens L5;
R11: a curvature radius of an object side surface of the 6th lens L6;
R12: a curvature radius of an image side surface of the 6th lens L6;
R13: a curvature radius of an object side surface of the 7th lens L7;
R14: a curvature radius of an image side surface of the 7th lens L7;
R15: a curvature radius of an object side surface of the 8th lens L8;
R16: a curvature radius of an image side surface of the 8th lens L8;
R17: a curvature radius of an object side surface of the glass flat plate GF;
R18: a curvature radius of an image side surface of the glass flat plate GF;
d: a center thickness of a lens or an on-axis distance between lenses;
d1: a center thickness of the 1st lens L1;
d2: an on-axis distance from the image side surface of the 1st lens L1 to the object side surface of the 2nd lens L2;
d3: a center thickness of the 2nd lens L2;
d4: an on-axis distance from the image side surface of the 2nd lens L2 to the object side surface of the 3rd lens L3;
d5: a center thickness of the 3rd lens L3;
d6: an on-axis distance from the image side surface of the 3rd lens L3 to the object side surface of the 4th lens L4;
d7: a center thickness of the 4th lens L4;
d8: an on-axis distance from the image side surface of the 4th lens L4 to the object side surface of the 5th lens L5;
d9: a center thickness of the 5th lens L5;
d10: an on-axis distance from the image side surface of the 5th lens L5 to the object side surface of the 6th lens L6;
d11: a center thickness of the 6th lens L6;
d12: an on-axis distance from the image side surface of the 6th lens L6 to the object side surface of the 7th lens L7;
d13: a center thickness of the 7th lens L7;
d14: an on-axis distance from the image side surface of the 7th lens L7 to the object side surface of the 8th lens L8;
d15: a center thickness of the 8th lens L8;
d16: an on-axis distance from the image side surface of the 8th lens L8 to the object side surface of the glass flat plate GF;
d17: a center thickness of the glass flat plate GF;
d18: an on-axis distance from the image side surface of the glass flat plate GF to an image surface;
nd: a refractive index of d line;
nd1: a refractive index of d line of the 1st lens L1;
nd2: a refractive index of d line of the 2nd lens L2;
nd3: a refractive index of d line of the 3rd lens L3;
nd4: a refractive index of d line of the 4th lens L4;
nd5: a refractive index of d line of the 5th lens L5;
nd6: a refractive index of d line of the 6th lens L6;
nd7: a refractive index of d line of the 7th lens L7;
nd8: a refractive index of d line of the 8th lens L8;
nd9: a refractive index of d line of the glass flat plate GF;
ν: Abbe number;
ν1: Abbe number of the 1st lens L1;
ν2: Abbe number of the 2nd lens L2;
ν3: Abbe number of the 3rd lens L3;
ν4: Abbe number of the 4th lens L4;
ν5: Abbe number of the 5th lens L5;
ν6: Abbe number of the 6th lens L6;
ν7: Abbe number of the 7th lens L7;
ν8: Abbe number of the 8th lens L8;
ν9: Abbe number of the glass flat plate GF;
TTL: a total track length (an on-axis distance from the object side surface of the 1st lens L1 to the image surface);
LB: an on-axis distance from the image side surface of the 8th lens L8 to the image surface (including a thickness of the glass flat plate GF).
y=(x2/R)/[1+{1−(k+1)(x2/R2)}1/2]+A4x4+A6x6+A8x8+A10x10+A12x12+A14x14+A16x16 (7)
For the sake of convenience, the aspherical surface shown in formula (7) is taken as aspheric surfaces of respective lens surfaces. However, the present disclosure is not limited to an aspherical polynomial form expressed by formula (7).
Table 19 presented later on shows a variety of numerical of Embodiment 1 to Embodiment 6 and values corresponding to parameters specified in the conditional formulas (1) to (6).
As shown in Table 19, Embodiment 1 satisfies the conditional formulas (1) to (6).
According to the camera lens LA of Embodiment 1, axial aberration is shown in
As shown in Table 19, Embodiment 2 satisfies the conditional formulas (1) to (6).
According to the camera lens LA of Embodiment 2, axial aberration is shown in
As shown in Table 19, Embodiment 3 satisfies the conditional formulas (1) to (6).
According to the camera lens LA of Embodiment 3, axial aberration is shown in
As shown in Table 19, Embodiment 4 satisfies the conditional formulas (1) to (6).
According to the camera lens LA of Embodiment 4, axial aberration is shown in
As shown in Table 19, Embodiment 5 satisfies the conditional formulas (1) to (6).
According to the camera lens LA of Embodiment 5, axial aberration is shown in
As shown in Table 19, Embodiment 6 satisfies the conditional formulas (1) to (6).
According to the camera lens LA of Embodiment 6, axial aberration is shown in
Table 19 presented later on shows values corresponding to parameters specified in conditional formulas (1) to (6) according to Embodiment 1 to Embodiment 6.
The scope of the present disclosure is not limited to the above-described embodiments, and any ordinarily skilled in the art, within the content disclosed by the present disclosure, may make equivalent modifications or variations, which should be covered within the protection scope of the claims.
Number | Date | Country | Kind |
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2018-137214 | Jul 2018 | JP | national |
Number | Name | Date | Kind |
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20170052350 | Chen | Feb 2017 | A1 |
20200026039 | Teraoka | Jan 2020 | A1 |
20200026040 | Teraoka | Jan 2020 | A1 |
20200026041 | Teraoka | Jan 2020 | A1 |
20200026042 | Teraoka | Jan 2020 | A1 |
Number | Date | Country | |
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20200026042 A1 | Jan 2020 | US |