Wide-angle projection lens and projection apparatus using...

Details Wide-angle projection lens and projection apparatus using... Wide-angle projection lens and projection apparatus using...

2008-10-02

2010-10-26

Thompson, Timothy J (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S681000

Reexamination Certificate

active

07821722

ABSTRACT:
A wide-angle projection lens and a projection apparatus using the same are provided. The wide-angle projection lens, from an image side of the projection apparatus, includes a first lens group, a second lens group and a third lens group. An aperture stop of the wide-angle projection lens is disposed in the third lens group. The first lens group has a negative effective refractive power and at least one aspheric lens surface. The second lens group has a first positive effective refractive power. The third lens group has a second positive effective refractive power. The effective focal length of the wide-angle projection lens is between 6.5 mm and 9.5 mm.

REFERENCES:
patent: 6285509 (2001-09-01), Nakayama et al.
patent: 7173777 (2007-02-01), Lu et al.
patent: 7227682 (2007-06-01), Caldwell et al.
patent: 2001/0012160 (2001-08-01), Takatsuki

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