US2015370047A1PendingUtilityA1

Imaging lens

Assignee: OPTICAL LOGIC INCPriority: Sep 1, 2011Filed: Aug 28, 2015Published: Dec 24, 2015

Est. expirySep 1, 2031(~5.1 yrs left)· nominal 20-yr term from priority

Inventors:Yoji Kubota Kenichi Kubota Hitoshi Hirano Ichiro Kurihara Yoshio Ise Tomohiro Yonezawa

G02B 9/60G02B 13/0045G02B 13/18G02B 13/0015

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References

Claims

Abstract

An imaging lens includes a first lens having positive refractive power; a second lens; a third lens; a fourth lens; and a fifth lens having negative refractive power, arranged in this order from an object side to an image plane side. The first lens is formed in a shape so that an object side surface thereof has a positive curvature radius. The second lens is formed in a shape so that an object side surface thereof and an image plane side surface thereof have positive curvature radii. The first lens, the third lens, and the second lens have specific Abbe's numbers. The third lens has a specific focal length so that a specific conditional expression is satisfied. The second lens, the third lens, and the fourth lens are arranged so that a specific conditional expression is satisfied.

Claims

exact text as granted — not AI-modified

What is claimed is: 
     
         1 . An imaging lens comprising:
 a first lens having positive refractive power;   a second lens;   a third lens;   a fourth lens; and   a fifth lens having negative refractive power, arranged in this order from an object side to an image plane side,   wherein said first lens is formed in a shape so that a curvature radius of a surface thereof on the object side is positive,   said second lens is formed in a shape so that a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image plane side are both positive,   each of said first lens and said third lens has an Abbe&#39;s number greater than 45,   said second lens has an Abbe&#39;s number less than 35,   said third lens has a focal length f 3  so that the following conditional expression is satisfied:
   5.58≦| f 3|/ f≦ 16.23
 
   
       where f is a focal length of a whole lens system,
 said second lens and said third lens are arranged so that the surface of the second lens on the image plane side is situated away from a surface of the third lens on the object side by a distance dA on an optical axis, and 
 said third lens and said fourth lens are arranged so that a surface of the third lens on the image plane side is situated away from a surface of the fourth lens on the object side by a distance dB on the optical axis so that the following conditional expression is satisfied:
   0.3&lt; dA/dB&lt; 1.5. 
 
 
     
     
         2 . The imaging lens according to  claim 1 , wherein said second lens has negative refractive power,
 said third lens has positive refractive power, and   said fourth lens has negative refractive power.   
     
     
         3 . The imaging lens according to  claim 1 , wherein said third lens is formed in a shape so that a curvature radius of a surface thereof on the object side is positive, and
 said fifth lens is formed in a shape so that a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image plane side are both positive.   
     
     
         4 . The imaging lens according to  claim 1 , wherein each of said fourth lens and said fifth lens has an Abbe&#39;s number greater than 45. 
     
     
         5 . The imaging lens according to  claim 1 , wherein said fourth lens is formed in a shape so that a curvature radius of the surface thereof on the object side and a curvature radius of a surface thereof on the image plane side are both negative. 
     
     
         6 . The imaging lens according to  claim 1 , wherein said second lens has a focal length f 2  so that the following conditional expression is satisfied:
   −1.8&lt; f 2/ f&lt;− 0.8.
 
 
     
     
         7 . The imaging lens according to  claim 1 , wherein said first lens has a focal length f 1 , and said second lens has a focal length f 2  so that the following conditional expression is satisfied:
   −1.0&lt; f 1/ f 2&lt;−0.4.
 
 
     
     
         8 . The imaging lens according to  claim 1 , wherein said second lens is formed in the shape so that the surface thereof on the object side has the curvature radius R 2   f  and the surface thereof on the image plane side has the curvature radius R 2   r  so that the following conditional expression is satisfied:
   1.5&lt; R 2 f/R 2 r&lt; 6.0.   
     
     
         9 . The imaging lens according to  claim 1 , wherein said second lens has a focal length f 2 , and said fifth lens has a focal length f 5  so that the following conditional expressions are satisfied:
   | f 2|&lt; f 3 and | f 2|&lt;| f 5|. 
 
     
     
         10 . The imaging lens according to  claim 1 , wherein said first lens has a focal length f 1 , and said fourth lens has a focal length f 4  so that the following conditional expressions are satisfied:
     f 1&lt; f 3 and  f 3&lt;| f 4|. 
 
     
     
         11 . An imaging lens comprising:
 a first lens having positive refractive power;   a second lens;   a third lens having positive refractive power;   a fourth lens; and   a fifth lens, arranged in this order from an object side to an image plane side,   wherein said first lens is formed in a shape so that a curvature radius of a surface thereof on the object side and a curvature radius of a surface thereof on the image plane side are both positive,   said second lens is formed in a shape so that a surface thereof on the image plane side is aspherical, and a curvature radius of a surface thereof on the object side and a curvature radius of the surface thereof on the image plane side are both positive,   said third lens is formed in a shape so that at least one of a surface thereof on the object side and a surface thereof on the image plane side is aspherical,   said fourth lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side are aspherical, and a curvature radius of the surface thereof on the image plane side is negative,   said fifth lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side are aspherical,   said second lens has a focal length f 2 , said third lens has a focal length f 3 , said fourth lens has a focal length f 4 , and said fifth lens has a focal length f 5  so that the following conditional expressions are satisfied:
     f 3&lt;| f 4| and | f 2|&lt;| f 5|. 
   
     
     
         12 . The imaging lens according to  claim 11 , wherein said second lens has negative refractive power,
 said fourth lens has negative refractive power, and   said fifth lens has negative refractive power.   
     
     
         13 . The imaging lens according to  claim 11 , wherein said third lens is formed in a shape so that a curvature radius of the surface thereof on the object side is positive, and
 said fifth lens is formed in a shape so that a curvature radius of the surface thereof on the object side and a curvature radius of the surface thereof on the image plane side are both positive.   
     
     
         14 . The imaging lens according to  claim 11 , wherein each of said first lens, said third lens, said fourth lens, and said fifth lens has an Abbe&#39;s number greater than 45, and
 said second lens has an Abbe&#39;s number less than 35.   
     
     
         15 . The imaging lens according to  claim 11 , wherein said first lens has a focal length f 1  so that the following conditional expressions are satisfied:
     f 1&lt; f 3 and | f 2|&lt; f 3. 
 
     
     
         16 . The imaging lens according to  claim 11 , wherein said second lens has the focal length f 2  so that the following conditional expression is satisfied:
   −1.8&lt; f 2/ f&lt;− 0.8
 
 
       where f is a focal length of a whole lens system. 
     
     
         17 . The imaging lens according to  claim 11 , wherein said first lens has a focal length f 1  so that the following conditional expression is satisfied:
   −1.0&lt; f 1/ f 2&lt;−0.4.
 
 
     
     
         18 . The imaging lens according to  claim 11 , wherein said second lens is formed in the shape so that the surface thereof on the object side has the curvature radius R 2   f  and the surface thereof on the image plane side has the curvature radius R 2   r  so that the following conditional expression is satisfied:
   1.5&lt; R 2 f/R 2 r&lt; 6.0.   
     
     
         19 . The imaging lens according to  claim 11 , wherein said second lens and said third lens are arranged so that the surface of the second lens on the image plane side is situated away from the surface of the third lens on the object side by a distance dA on an optical axis, and
 said third lens and said fourth lens are arranged so that the surface of the third lens on the image plane side is situated away from the surface of the fourth lens on the object side by a distance dB on the optical axis so that the following conditional expression is satisfied:
   0.3&lt; dA/dB&lt; 1.5. 
   
     
     
         20 . The imaging lens according to  claim 11 , wherein said third lens has the focal length f 3  so that the following conditional expression is satisfied:
   5.0&lt; f 3/ f&lt; 20.0 
 
       where f is a focal length of a whole lens system.

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