1. Technical Field
The present disclosure relates to lenses and, particularly, to an image lens with high resolution and small distance.
2. Description of Related Art
Image sensors are used to capture an image. A size of an image sensor, such as a complementary metal oxide semiconductor device (CMOS), decreases with development of technology. For proper matching with the image sensor, an image lens, which is essentially comprised of a number of lenses, should be able to meet requirements, such as, high resolution and small distance. However, the existing image lenses cannot meet these requirements, thus, results in poor imaging effect.
Therefore, it is desirable to provide an image lens which can overcome the limitations described above.
Embodiments of the disclosure will now be described in detail with reference to the accompanying drawings.
The first lens L1 includes a convex first surface S1 facing the object side and a convex second surface S2 facing the image side.
The second lens L2 includes a convex third surface S3 facing the object side and a concave fourth surface S4 facing the image side.
The third lens L3 includes a convex third surface S5 facing the object side and a convex sixth surface S6 facing the image side.
The fourth lens L4 includes a concave seventh surface S7 facing the object side and a convex eighth surface S8 facing the image side.
The fifth lens L5 includes a concave ninth surface S9 facing the object side and a concave tenth surface S10 facing the image side.
The IR-cut filter 10 includes an eleventh surface S11 facing the object side and a twelfth surface S12 facing the image side.
The image lens 100 further includes an aperture stop 30. The aperture stop 30 is positioned between the first lens L1 and the second lens L2. Light rays enter the image lens 100, passing through the first lens L1, the aperture stop 30, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the IR-cut filter 10, finally forming optical images on the image plane 20. The aperture stop 30 is for adjusting light flux from the first lens L1 to the second lens L2. In addition, the aperture stop 30 facilitates uniform light transmission when light passes through the first lens L1 to correct coma aberrations of the image lens 100. The IR-cut filter 10 filters/removes infrared light from the light rays.
The image lens 100 satisfies the formulas:
D/TTL>0.94; (1)
D/L>1.21; (2)
wherein D is the maximum image diameter of the image plane 20; TTL is a total length of the image lens 100; L is a distance from an outmost edge of the tenth surface S10 to an optical axis of the image lens 100 along a direction perpendicular to the optical axis of the image lens 100.
The formulas (1) to (2) are for shortening the length of the image lens 100, and reducing the aberration of the field curvature and spherical aberration in the zoom process. If the image lens 100 does not satisfy the formulas (1) to (2), the distance of the image lens 100 cannot be maintained and the images captured by the image lens 100 cannot be corrected.
The image lens 100 further satisfies the formula:
Z/Y>0; (3)
wherein Z is a distance from a central point of the seventh surface S7 to an outmost edge of the eighth surface S8 along the optical axis, Y is a distance from an outmost edge of the eighth surface S8 to the optical axis along a direction perpendicular to the optical axis.
Formula (3) is for properly distributing the refraction power, while maintaining a relatively small spherical aberration.
The image lens 100 further satisfies the formulas:
R31/F3>R11/F1>0; (4)
R12/F1<R32/F3<0; (5)
wherein R11 is the curvature radius of the first surface S1 of the first lens L1; R12 is the curvature radius of the second surface S2 of the first lens L1; R31 is the curvature radius of the fifth surface S5 of the third lens L3, R32 is the curvature radius of the sixth surface S6 of the third lens L3; F1 is focal length of the first lens L1, and F3 is focal length of the third lens L3.
Formulas (4)-(5) are for maintaining quality of images captured by the image lens 100. If the image lens 100 does not satisfy the formulas (4) to (5), the images captured by the image lens 100 cannot be corrected.
The image lens 100 further satisfies the formulas:
R51/F5<R52/F5<0; (6)
wherein R51 is the curvature radius of the ninth surface S9 of the fifth lens L5; R52 is the curvature radius of the tenth surface S10 of the fifth lens L5; F5 is focal length of the fifth lens L5.
Formula (6) is for correcting chromatic aberration of the image lens 100. If the image lens 100 does not satisfy the formula (6), the images captured by the image lens 100 will have a greater chromatic aberration.
All of the first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9 and S10 are aspherical surfaces. Each aspherical surface is shaped according to the formula:
wherein Z is the length of a line drawn from a point on the aspherical surface to the tangential plane of the aspherical surface, h is the height from the optical axis to the point on the aspherical surface, c is a vertex curvature (=1/R, the radius of curvature), k is a conic constant, and Ai are the correction coefficients, to the order of “i” of the aspherical surface.
Detailed examples of the imaging lens 100 are given below in accompany with
FNo: F number;
2ω: field angle;
ri: radius of curvature of the surface Si;
Di: distance between surfaces on the optical axis of the surface Si and the surface Si+1;
Ni: refractive index of the surface Si;
Vi: Abbe constant of the surface Si;
Ki: Secondary curvature of the surface Si.
Tables 1-4 show a first embodiment of the image lens 100.
In the embodiment, D=5.867 mm; TTL=5.48 mm; Z=0.137 mm; Y=1.45 mm; L=4.47 mm; F1=3.32; F3=7.99 mm; F5=−2.57 mm.
Tables 5-8 show a second embodiment of the image lens 100.
In the embodiment, D=5.867 mm; TTL=5.66 mm; Z=0.121 mm; Y=1.44 mm; L=4.42 mm; F1=3.55 mm; F3=7.78 mm; F5=−2.63 mm.
Particular embodiments are shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.
Number | Date | Country | Kind |
---|---|---|---|
101105944 A | Feb 2012 | TW | national |
Number | Name | Date | Kind |
---|---|---|---|
7177098 | Arai | Feb 2007 | B2 |
8520124 | Ozaki | Aug 2013 | B2 |
20100220229 | Sano | Sep 2010 | A1 |
20120250167 | Hashimoto | Oct 2012 | A1 |
20140146399 | Ko | May 2014 | A1 |
Number | Date | Country | |
---|---|---|---|
20130222893 A1 | Aug 2013 | US |