Zoom lens for projection and projection-type display apparatus

Details Zoom lens for projection and projection-type display apparatus Zoom lens for projection and projection-type display apparatus

2011-06-03

2011-12-20

Lester, Evelyn A. (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S681000, C359S682000, C359S683000, C359S684000, C359S685000, C359S686000, C359S714000, C359S740000, C359S770000

Reexamination Certificate

active

08081391

ABSTRACT:
A zoom lens for projection includes a negative first group composed of two lenses, a second group composed of a positive lens, an aperture stop, a third group composed of a positive lens, a fourth group composed of a negative fourth-group-first lens, a fourth-group-second lens arranged in such a manner that a negative air lens is formed between the fourth-group-first lens and the fourth-group-second lens, and a positive fourth-group-third lens, and a fifth group composed of a positive lens having a convex surface facing the magnification side of the zoom lens, which are arranged in this order from the magnification side. Further, the following formula (1) is satisfied:in-line-formulae description="In-line Formulae" end="lead"?−0.6<(R72+R71)/(R72−R71)<0.6  (1), wherein-line-formulae description="In-line Formulae" end="tail"?R71is a radius of curvature of a magnification-side surface of the fourth-group-third lens, andR72is a radius of curvature of a reduction-side surface of the fourth-group-third lens.

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