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Title:
OPTICAL SYSTEM FOR COPYING MACHINE OF THREE-GROUP THREE-LENS CONSTITUTION
Document Type and Number:
Japanese Patent JPH08190049
Kind Code:
A
Abstract:

PURPOSE: To provide an optical system for copying machine having high contrast and the brightness of F8 and capable of reducing the cost by using the glass of a low unit price by comprising the system of plural lens groups composed of single lenses, respectively, and satisfying a specified condition.

CONSTITUTION: This system is composed of a first lens group composing of a single lens having a positive refractive power, a second lens group composed of a single lens having a negative refractive power and a third lens group composed of a single lens having a positive refractive power successively arranged from the object side. The respective conditions: 0.37f<f1<1.6f, -0.31f<f2<0.19f, 1.55<n1<1.65, 2.3<(ν1+ν3)/ν2<3.3 are satisfied, where, f: the composite focal distance of a whole system for (d) line, f1, f2: focal distances of the first lens group and the second lens group for (d) line, respectively, n1: the refractive index of the first lens group for (d) line and ν1-ν3: the Abbe numbers of the first to the third lens groups 1-3, respectively.


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Inventors:
NISHINA KIICHIRO
Application Number:
JP1886295A
Publication Date:
July 23, 1996
Filing Date:
January 12, 1995
Export Citation:
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Assignee:
RICOH KK
International Classes:
G02B9/16; G02B13/24; (IPC1-7): G02B13/24; G02B9/16
Attorney, Agent or Firm:
Shuji Sanada