Projection lens system and projection type display apparatus...

Details Projection lens system and projection type display apparatus... Projection lens system and projection type display apparatus...

2011-06-21

2011-06-21

Spector, David N (Department: 2873)

Optical: systems and elements

Lens

With field curvature shaping

C359S663000, C353S033000

Reexamination Certificate

active

07965449

ABSTRACT:
A projection lens system includes, in order from the magnification side, a negative first lens group and a positive second lens group, and is telecentric on the reduction side. The first lens group includes a first lens formed as an aspheric lens which is disposed closest to the magnification side. The second lens group includes a second lens formed as a positive lens, in or near which an aperture diaphragm is disposed, disposed closest to the magnification side, and an aspheric lens. Between the aperture diaphragm and the aspheric lens of the second lens group, two or more negative lenses and two or more cemented surfaces are disposed. And, 0.10<f/f2-1<0.30, and N2-1>1.75 are satisfied. Here, f denotes a focal length of the whole system, f2-1denotes a focal length of the second lens, and N2-1is a refractive index of the second lens at the d-line.

REFERENCES:
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patent: 7289270 (2007-10-01), Yamamoto
patent: 7355799 (2008-04-01), Yamamoto
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patent: 7529033 (2009-05-01), Yamamoto
patent: 2003/0137744 (2003-07-01), Kuwa et al.
patent: 2004/0257666 (2004-12-01), Komatsu et al.
patent: 2003-15033 (2003-01-01), None
patent: 2004-326079 (2004-11-01), None
patent: 2008-309988 (2008-12-01), None

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