Optics: image projectors – Lamp control
Reexamination Certificate
2007-12-11
2007-12-11
Sever, Andrew T (Department: 2851)
Optics: image projectors
Lamp control
C353S084000, C353S121000, C348S743000
Reexamination Certificate
active
11116035
ABSTRACT:
This invention provides a method of operating a projection system wherein light emitted from a high-pressure discharge lamp being lit with d.c. lamp current is passed through color segments of a color filter sequentially and then reflected by an optical element to project an image on a screen, the color segments of the color filter including red, green and blue color segments and a color segment comprising a green ND filter having a relatively low lightness. The method includes making lower a crest value of the d.c. lamp current fed to the high-pressure discharge lamp for a first illumination period during which the color segment comprising the green ND filter is illuminated than a crest value of the d.c. lamp current fed to the high-pressure discharge lamp for a second illumination period during which any one of the other color segments is illuminated, in synchronism with the first illumination period.
REFERENCES:
patent: 5706061 (1998-01-01), Marshall et al.
patent: 5917558 (1999-06-01), Stanton
patent: 6803894 (2004-10-01), Hirota et al.
patent: 6879451 (2005-04-01), Hewlett et al.
patent: 2004-319193 (2004-11-01), None
Fujii Toshitaka
Nakagawa Atsuji
Jordan and Hamburg LLP
Phoenix Electric Co. Ltd.
Sever Andrew T
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