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Patent Searching and Data


Title:
IMAGE FORMING LENS
Document Type and Number:
Japanese Patent JPH07104185
Kind Code:
A
Abstract:

PURPOSE: To obtain the image forming lens for reading an image, which is short in overall length of the lens system, miniature and inexpensive and satisfactory in the quality of a formed image by providing a first and a fourth biconvex lenses and a second and a third biconcave lenses, and allowing them to satisfy specific conditions.

CONSTITUTION: This lens is provided with a first lens L1 consisting of a biconvex lens, a second and a third lenses L2, L3 consisting of a biconcave lens, respectively and a fourth lens L4 consisting of a biconvex lens in order from an object side, and constituted so as to satisfy conditional expressions shown by 0.35<f1/f<0.51, 0.34<f4/f<0.45, 0.11<d7/f<0.16, and 0.29<d/f<0.41. In this case, (f), f1, f4, (d) and d7 denote a composite focal length of the whole system, a focal length of a first lens L1, a focal length of a fourth lens L4, a distance on an optical axis between the face of the object side of a first lens L1 and the face of an image side of a fourth lens L4, and thickness on the optical axis of a fourth lens L4, respectively. Also, a diaphragm (i) is provided between a third lens L3 and a fourth lens L4.


Inventors:
YAMAKAWA HIROMITSU
Application Number:
JP25152593A
Publication Date:
April 21, 1995
Filing Date:
October 07, 1993
Export Citation:
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Assignee:
FUJI PHOTO OPTICAL CO LTD
International Classes:
G02B9/36; G02B13/24; (IPC1-7): G02B13/24
Attorney, Agent or Firm:
Seiji Yanagida (1 person outside)