Title:
SINGLE FOCAL LENS
Document Type and Number:
Japanese Patent JP3768509
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To attain a high-performance compact lens system by effectively using aspherical surfaces, even though the lens system is constituted of a small number of lenses.
SOLUTION: A 1st positive lens G1 constituted of glass material, a diaphragm St, a 2nd positive lens G2 constituted of a plastic aspherical lens and a 3rd negative lens G3 constituted of a plastic aspherical lens are arranged in this order from an object side, and also, the system satisfies the following conditional inequalities: 0.6<R1/f<0.8 ...(1), -1.0<f3/f<0 ... (2) and 0.60<tanθ<0.70 ...(3), provided that f denotes the paraxial focal distance of the whole lens system, f3 denotes the paraxial focal distance of the 3rd lens G3, R1 denotes the curvature radius of the object side surface of the 1st lens G1 and θ denotes a half viewing angle at the maximum image height.
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Inventors:
Kenichi Sato
Application Number:
JP2004098420A
Publication Date:
April 19, 2006
Filing Date:
March 30, 2004
Export Citation:
Assignee:
Fujinon Co., Ltd.
International Classes:
G02B13/00; G02B1/04; G02B9/12; G02B13/06; G02B13/18; G02B15/14; G02B15/163; (IPC1-7): G02B13/00; G02B13/18
Domestic Patent References:
| JP26917A | ||||
| JP2003322792A | ||||
| JP7333502A | ||||
| JP2004163850A | ||||
| JP2004163786A | ||||
| JP8160298A | ||||
| JP2004326097A | ||||
| JP200555852A | ||||
| JP200584387A | ||||
| JP200591513A | ||||
| JP200555751A | ||||
| JP2005242286A | ||||
| JP2004163849A |
Foreign References:
| US20040021957 |
Attorney, Agent or Firm:
Yasushi Santanzaki
Yoichiro Fujishima
Yoichiro Fujishima
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