Variable power optical system for copying machine

Details Variable power optical system for copying machine Variable power optical system for copying machine

1994-12-07

1996-11-05

Epps, Georgia Y.

Optical: systems and elements

Lens

With variable magnification

G02B 1514

Patent

active

055723667

ABSTRACT:
A variable power optical system for a copying machine includes a first lens group having a negative power, a second lens group having a positive power, and a third lens group having a negative power. All three lens groups are moved to vary distances D.sub.1 and D.sub.2 between the first and second lens groups and between the second and third lens groups, to thereby vary the magnification in a range from an actual size to an enlargement range, while maintaining a constant distance between an object and an object image. In the range from the actual size to the enlargement range, the optical system satisfies the relationship defined by 0.60<.vertline.(D.sub.m1 -D.sub.e1)/(D.sub.m2 -D.sub.e2).vertline.<0.85, wherein "D.sub.mi " designates a value of D.sub.i (i=1,2) at a maximum magnification, and "D.sub.ei " designates a value of D.sub.i (i=1,2) at an actual size, respectively.

REFERENCES:
patent: 4359269 (1982-11-01), Itoh
patent: 4707082 (1987-11-01), Itoh
patent: 4735496 (1988-04-01), Arai
patent: 4813773 (1989-03-01), Minefuji
patent: 4997265 (1991-03-01), Nishina
patent: 5270864 (1993-12-01), Watanabe

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