Optical: systems and elements – Lens – With field curvature shaping
Reexamination Certificate
2005-04-20
2008-12-02
Collins, Darryl J (Department: 2873)
Optical: systems and elements
Lens
With field curvature shaping
C359S793000
Reexamination Certificate
active
07460307
ABSTRACT:
To provide a compact and low-cost projector lens capable of appropriately performing temperature correction and obtaining excellent image quality although using a plurality of plastic lens elements, a first lens unit having negative refractive power and a second lens unit having positive refractive power are provided from the screen side, the first lens unit includes a negative meniscus lens element1bbeing a plastic lens element, being convex to the screen side and having an aspherical surface, the second lens unit includes: a negative lens element2bbeing a plastic lens element and having an aspherical surface; and at least two positive lens elements having anomalous dispersibility and a temperature coefficient of a negative refractive index, and an image plane fluctuation by a temperature change due to a temperature coefficient of a negative refractive index of the plastic lens elements1band2bof the first and second lens units is corrected by the temperature coefficient of the predetermined negative refractive index of the positive lens elements.
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patent: 2005/0219706 (2005-10-01), Yamagishi
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Kitaoka Yasuhisa
Muramatsu Akihiro
Collins Darryl J
Harness Dickey & Pierce PLC
Panasonic Corporation
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