Optical: systems and elements – Projection screen – Rear projection screen
Reexamination Certificate
2005-08-08
2009-06-23
Lee, Diane I (Department: 2851)
Optical: systems and elements
Projection screen
Rear projection screen
C359S457000
Reexamination Certificate
active
07551352
ABSTRACT:
To eliminate or otherwise reduce non-uniform brightness of an image of a display apparatus, an image is projected through a projection optical system having a projection lens (2), curved surface reflection mirrors (4and5), and a reflection mirror (6) onto a rear surface of the rear-surface projection type screen (3). The rear-surface projection type screen includes a Fresnel lens sheet (8), wherein the prism surfaces of the Fresnel lens are formed in an aspheric configuration, thereby letting the light beams from the screen to exit at an exit angle of about zero (0) degree relative to a line perpendicular to the screen surface, over most of the entire surface thereof. It is possible to obtain a projection image that having uniform brightness in an image display apparatus while maintaining a thin cabinet (7) profile.
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Hirata Koji
Hisada Takanori
Imafuku Daisuke
Ohishi Tetsu
Yatsu Masahiko
Cruz Magda
Hitachi , Ltd.
Lee Diane I
Townsend and Townsend / and Crew LLP
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