Projection zoom lens and projection type display device

Details Projection zoom lens and projection type display device Projection zoom lens and projection type display device

2008-11-24

2009-10-20

Lester, Evelyn A. (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S681000, C359S682000, C359S683000, C359S713000, C359S740000, C359S749000, C359S752000, C359S761000

Reexamination Certificate

active

07605985

ABSTRACT:
A projection zoom lens is provided and includes: in order from the magnification side, a negative first lens group performing focusing with being fixed during power-varying; a positive second lens group, a positive third lens group, a positive fourth lens group, a positive fifth lens group, which are moved with correlation; and a positive sixth lens group fixed during the power-varying. An aperture diaphragm is moved between the fourth lens group and the fifth lens group during the power-varying to keep Fno constant in the whole power-varying region. In addition, the expression of 1.7<Bf/f<3.0 is satisfied, where f is a focal length of the whole system, and Bf is a back focal length (air conversion distance) of the whole system.

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patent: 2008-46259 (2008-02-01), None
patent: 2008-83229 (2008-04-01), None

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