CN107870409B - Short TTL lens of big angle of view - Google Patents
Short TTL lens of big angle of view Download PDFInfo
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- CN107870409B CN107870409B CN201711052720.2A CN201711052720A CN107870409B CN 107870409 B CN107870409 B CN 107870409B CN 201711052720 A CN201711052720 A CN 201711052720A CN 107870409 B CN107870409 B CN 107870409B
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- 230000003287 optical effect Effects 0.000 claims abstract description 54
- 230000014509 gene expression Effects 0.000 claims description 24
- 230000005499 meniscus Effects 0.000 claims description 3
- 230000004075 alteration Effects 0.000 description 5
- 238000012546 transfer Methods 0.000 description 5
- 238000013461 design Methods 0.000 description 4
- 238000003384 imaging method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 238000010191 image analysis Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 238000005452 bending Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
Classifications
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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
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/06—Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
Abstract
The invention relates to a large-field-angle short TTL lens, which comprises an aperture diaphragm, 4 lenses and an optical filter, wherein the first lens and the third lens have positive focal power, the second lens and the fourth lens have negative focal power, and the object side optical surface and the image side optical surface of the second lens are concave surfaces; the object-side optical surface of the third lens element is concave, and the image-side optical surface of the third lens element is convex; the fourth lens is M-shaped when seen from the object side to the image side; the following conditions are satisfied: 0.2<(d 1 +d 2 +d 3 )/ih<0.4，0.5<(T 1 +T 2 +T 3 +T 4 )/ih<0.8；d 1 D is the air gap between the first lens and the second lens 2 D is the air gap between the second lens and the third lens 3 T is the air gap between the third lens and the fourth lens 1 To T 4 The center thickness of the 4 lenses is the maximum image height ih. The lens has good performance in the aspects of short TTL, high brightness, large view field and high image resolution.
Description
Technical Field
The invention relates to a high-pixel intelligent mobile phone or ultrathin video shooting electronic equipment, in particular to a short TTL lens with a large field angle.
Background
Along with the development of science and technology, various portable electronic devices tend to be more miniaturized and lighter, wherein portable electronic devices with camera shooting function, such as smart phones, tablet computers, smart watches, AR glasses and the like, have shorter requirements on camera shooting lenses, and meanwhile, high resolution, high brightness, large field of view and low cost are also required.
For these demands, for example, in order to achieve miniaturization and ultra-thin, a 4-sheet structure is used, and the more number of lenses, the more difficulty in ultra-thin short TTL (distance from the forefront of the lens to the image plane) is increased, but the smaller number of lenses is disadvantageous in correcting peripheral aberrations. There have been many patents on 4-sheet type structures, and the prior art has a structure with an optical total length of less than 3.4mm, but the field of view is generally between 60 ° and 80 °. The method is poor in short TTL, high brightness, large field of view and high image resolution.
Disclosure of Invention
The embodiment of the invention provides a short TTL lens with a large field angle, which has good performance in the aspects of short TTL, high brightness, large field of view and high image resolution.
The invention provides a large-field-angle short TTL lens, which comprises an aperture diaphragm, 4 lenses and an optical filter, wherein the aperture diaphragm, the 4 lenses and the optical filter are sequentially arranged from an object side to an image side along an optical axis; the third lens element has a meniscus configuration, wherein the object-side surface of the third lens element is concave, and the image-side surface of the third lens element is convex; the fourth lens is M-shaped when seen from the object side to the image side; and satisfies the following conditional expression:
wherein d 1 D is the air gap between the first lens and the second lens 2 D is the air gap between the second lens and the third lens 3 T is the air gap between the third lens and the fourth lens 1 、T 2 、T 3 And T 4 The thicknesses of centers of the first lens, the second lens, the third lens and the fourth lens are respectively, and ih is the maximum image height.
In the large-field-angle short TTL lens, the lens of the lens meets the following conditional expression: 1.2<d 1 /d 2 <1.7。
In the large-field-angle short TTL lens of the present invention, the second lens and the third lens satisfy the following conditional expression: 0.2<T 2 /T 3 <0.5。
In the large-field-angle short TTL lens of the present invention, the second lens satisfies the following conditional expression: n (N) 2 >1.64, where N 2 Is the refractive index of the second lens.
In the large-field-angle short TTL lens of the present invention, the second lens satisfies the following conditional expression:
-3.8<f 2 /f<-2.5；
wherein f 2 F is the focal length of the whole optical system of the lens; r is R 3 And R is 4 The radii of curvature of the object-side and image-side surfaces of the second lens element, respectively.
In the large-angle-of-view short TTL lens of the present invention, the fourth lens satisfies the following conditional expression:
-1.2<f 4 /f<-0.3；
wherein f 4 F is the focal length of the whole optical system of the lens; r is R 7 And R is 8 The radii of curvature of the object-side and image-side optical surfaces of the fourth lens element, respectively.
In the large-angle-of-view short TTL lens, each lens surface of the lens adopts an even aspherical surface.
The large-angle-of-view short TTL lens has at least the following beneficial effects:
1. the mobile phone lens has good performance in the aspects of short TTL, high brightness, large view field and high image resolution.
2. The lens shape of the optical system of the lens is relatively symmetrical, and the lens is convenient for molding and production. And the distance between the lenses is reasonable, so that the later structural design is convenient.
3. The MTF transfer function curve graph (optical transfer function) of the optical system of the lens can comprehensively reflect the imaging quality of the system, the smoother the curve shape is, the higher the height relative to the X axis is, the better the imaging quality of the system is proved, and when the spatial frequency of the lens of the optical system is 110lp/mm, the MTF is more than 0.4 within a 0.9 field of view, and the lens has higher image analysis capability. The field curvature of the system is well corrected, and the distortion of each field of view is controlled within 2 percent.
Drawings
FIG. 1 is a two-dimensional view of an optical system of a large field angle short TTL lens of the present invention;
FIG. 2 is a graph of MTF transfer function of an optical system of a large field angle short TTL lens of the present invention;
FIG. 3 is a field curvature diagram of an optical system of the large field angle short TTL lens of the present invention;
FIG. 4 is a distortion characterization graph of an optical system of the large field angle short TTL lens of the present invention;
fig. 5 is a defocus graph of the optical system of the large field angle short TTL lens of the present invention.
Detailed Description
The invention provides a large-field-angle short TTL lens, the two-dimensional diagram of an optical system of which is shown in fig. 1, wherein the lens comprises an aperture diaphragm, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4 and an optical filter 5 which are sequentially arranged from an object side to an image side along an optical axis. The first lens element 1 and the third lens element 3 have positive optical power, the second lens element 2 and the fourth lens element 4 have negative optical power, and both the object-side optical surface and the image-side optical surface of the second lens element 2 are concave; the third lens element 3 has a meniscus shape, wherein an object-side optical surface of the third lens element 3 is a concave surface, and an image-side optical surface is a convex surface; the fourth lens 4 has an M shape as viewed from the object side to the image side. And satisfies the following conditional expression:
1.2<d 1 /d 2 <1.7（1）
0.2<T 2 /T 3 <0.5（2）
N 2 >1.64（3）
-3.8<f 2 /f<-2.5（4）
-1.2<f 4 /f<-0.3（6）
wherein d 1 D is the air gap between the first lens and the second lens 2 D is the air gap between the second lens and the third lens 3 T is the air gap between the third lens and the fourth lens 1 、T 2 、T 3 And T 4 The thicknesses of centers of the first lens, the second lens, the third lens and the fourth lens are respectively, and ih is the maximum image height. f (f) 2 F is the focal length of the second lens and f is the focal length of the whole optical system; r is R 3 And R is 4 The radii of curvature of the object-side and image-side surfaces of the second lens element, respectively. f (f) 4 F is the focal length of the whole optical system; r is R 7 And R is 8 The radii of curvature of the object-side and image-side optical surfaces of the fourth lens element, respectively.
The above conditional expression (1) defines a ratio of an air gap between the first lens and the second lens to an air gap between the second lens and the third lens, and if the ratio exceeds a lower limit value, the reduction in size is advantageous, but the correction of spherical aberration and curvature of field is disadvantageous. If the upper limit value is exceeded, miniaturization is not favored.
The above conditional expression (2) specifies the ratio of the center thicknesses of the second lens and the third lens, and satisfying this conditional expression is advantageous for correcting curvature of field.
Satisfying conditional expression (3) is advantageous for correcting spherical aberration and chromatic aberration.
The conditions (4) - (7) prescribe the relation between the optical power of the second lens and the fourth lens and the bending degree of each surface, and the reasonable distribution of the optical power is facilitated to achieve the purposes of shortening the total length, increasing the field of view and controlling the aberration to meet the actual use requirement.
Conditional expressions (8) to (9) limit the relation between the lens gap, the thickness and the image height, and satisfying the relation ensures the ultra-thinning of the whole system while the pixels are high.
The lens of the lens adopts even aspherical surfaces on each surface. Each aspherical coefficient satisfies the following equation:
wherein z represents the aspherical sagittal height, c represents the aspherical paraxial curvature, y represents the lens aperture, k represents the conic coefficient, A 4 Is the aspherical coefficient of 4 times, A 6 Is the aspherical coefficient of 6 times, A 8 Is an aspherical coefficient of 8 times, A 10 Is the aspheric coefficient of 10 times, A 12 Is 12 times of aspheric coefficient A 14 Is the aspherical coefficient of 14 times, A 16 Is the 16 th order aspheric coefficient.
The 4-sheet structure optical system of the large-angle-of-view short-TTL lens has TTL controlled below 3.4mm, maximum image height of 2.4mm, full angle of view of 87.5, FNo smaller than 2.0 and FBL (rear working distance) larger than 0.8mm, and is convenient for carrying IRCUT and image sensor. The lens structure and the surface shape are easy to design and mold.
Example 1: in this embodiment, the lens has a full field angle of 87.6, an aperture value of F2.0, an optical total length TTL (distance from the forefront of the lens to the image plane) of 3.36mm, and an image height to TTL ratio of 0.71.
Table 1 is a table of design parameters for the lens barrel of example 1.
Table 2 is an aspherical coefficient table of the lens of example 1.
Conditional [ ]1) D in (d) 1 /d 2 Has a value of 1.41, T in conditional expression (2) 2 /T 3 Has a value of 0.37, f in conditional expression (4) 2 The value of/f is-3.28, and in the conditional expression (5) (R 3 -R 4 )/(R 3 +R 4 ) Has a value of 2.95, f in conditional expression (6) 4 The value of/f is-0.83, and in the conditional expression (7) (R 7 -R 8 )/(R 7 +R 8 ) Has a value of 0.5, and in conditional expression (8), (d 1 +d 2 +d 3 ) The value of/ih was 0.22, and (T) in the conditional expression (9) 1 +T 2 +T 3 +T 4 ) The value of/ih is 0.71.
As shown in fig. 1, a two-dimensional view of the optical system is shown. The lens shape of the optical system is relatively symmetrical, and the optical system is convenient for molding production. And the distance between the lenses is reasonable, so that the later structural design is convenient.
As shown in FIG. 2, the MTF transfer function graph (optical transfer function) of the optical system can comprehensively reflect the imaging quality of the system, the smoother the curve shape, the higher the height relative to the X axis, the better the imaging quality of the system is proved, and when the spatial frequency of the lens of the optical system is 110lp/mm, the MTF is more than 0.4 within a 0.9 field of view, and the higher the image analysis capability is realized.
As shown in fig. 3 and fig. 4, the field curvature graph and the distortion characteristic curve of the optical system are respectively, the field curvature of the system is well corrected, and the distortion of each field of view is controlled within 2%.
As shown in fig. 5, a defocus graph of the optical system shows optical performance and defocus amounts of 0 field, 0.3 field, 0.5 field, 0.8 field, and 1.0 field, respectively. The closer the peak of the curve is to the center point, the better the optical performance, and the smaller the field area.
The foregoing description of the preferred embodiments of the invention is not intended to limit the scope of the invention, but rather to enable any modification, equivalent replacement, improvement or the like to be made without departing from the spirit and principles of the invention.
Claims (5)
1. The large-field-angle short TTL lens is characterized in that the lens is arranged along an optical axis and sequentially comprises an aperture diaphragm, 4 lenses and an optical filter from an object side to an image side, wherein the first lens and the third lens have positive focal power, the second lens and the fourth lens have negative focal power, and the object side optical surface and the image side optical surface of the second lens are concave surfaces; the third lens element has a meniscus configuration, wherein the object-side surface of the third lens element is concave, and the image-side surface of the third lens element is convex; the fourth lens is M-shaped when seen from the object side to the image side;
and satisfies the following conditional expression:
1.2<d 1 /d 2 <1.7
wherein d 1 D is the air gap between the first lens and the second lens 2 D is the air gap between the second lens and the third lens 3 T is the air gap between the third lens and the fourth lens 1 、T 2 、T 3 And T 4 The thickness of the center of the first lens, the second lens, the third lens and the fourth lens is respectively, and ih is the maximum image height;
the second lens satisfies the following conditional expression:
wherein f 2 F is the focal length of the whole optical system of the lens; r is R 3 And R is 4 The radii of curvature of the object-side and image-side surfaces of the second lens element, respectively.
2. The large field angle short TTL lens of claim 1, wherein said second and third lens satisfy the following conditional expression: 0.2<T 2 /T 3 <0.5。
3. The large field angle short TTL of claim 1The lens is characterized in that the second lens meets the following conditional expression: n (N) 2 >1.64, where N 2 Is the refractive index of the second lens.
4. The large field angle short TTL lens of claim 1, wherein said fourth lens satisfies the following conditional expression:
wherein f 4 F is the focal length of the whole optical system of the lens; r is R 7 And R is 8 The radii of curvature of the object-side and image-side optical surfaces of the fourth lens element, respectively.
5. The large field angle short TTL lens of claim 1, wherein each lens face of said lens employs an even aspherical surface.
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| CN201711052720.2A CN107870409B (en) | 2017-11-01 | 2017-11-01 | Short TTL lens of big angle of view |
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| CN201711052720.2A CN107870409B (en) | 2017-11-01 | 2017-11-01 | Short TTL lens of big angle of view |
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| CN107870409A CN107870409A (en) | 2018-04-03 |
| CN107870409B true CN107870409B (en) | 2023-11-24 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN204178038U (en) * | 2014-06-27 | 2015-02-25 | 康达智株式会社 | Pick-up lens |
| JP2015161760A (en) * | 2014-02-27 | 2015-09-07 | アウラディアス合同会社 | imaging lens |
| CN207473183U (en) * | 2017-11-01 | 2018-06-08 | 辽宁中蓝电子科技有限公司 | A kind of short TTL camera lenses of big field angle |
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| TWI386700B (en) * | 2008-05-28 | 2013-02-21 | E Pin Optical Industry Co Ltd | Short overall length imaging lens system with four lenses |
| TWI436125B (en) * | 2011-03-04 | 2014-05-01 | Largan Precision Co Ltd | Photographing optical lens assembly |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2015161760A (en) * | 2014-02-27 | 2015-09-07 | アウラディアス合同会社 | imaging lens |
| CN204178038U (en) * | 2014-06-27 | 2015-02-25 | 康达智株式会社 | Pick-up lens |
| CN207473183U (en) * | 2017-11-01 | 2018-06-08 | 辽宁中蓝电子科技有限公司 | A kind of short TTL camera lenses of big field angle |
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Effective date of registration: 20201130 Address after: 124000 No. 388 North China Road, Xinglongtai District, Panjin City, Liaoning Province Applicant after: Liaoning Zhonglan Photoelectric Technology Co.,Ltd. Address before: 124010 Zhonghua Road East, Xinglongtai District, Liaoning, Panjin Applicant before: LIAONING ZHONGLAN ELECTRONIC TECHNOLOGY Co.,Ltd. |
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