The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 23, 1990
Filed:
Aug. 10, 1989
Applicant:
Inventors:
Makoto Tachikawa, Hitachi, JP;
Osamu Suzuki, Hiratsuka, JP;
Tadahiko Hashimoto, Katsuta, JP;
Kuniyuki Igari, Hitachi, JP;
Ichirou Katsuyama, Hitachi, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Primary Examiner:
Int. Cl.
CPC ...
G03B / ;
U.S. Cl.
CPC ...
353 85 ;
Abstract
Brightness of a screen is detected on the basis of a luminous flux projected from a light source to the screen. This detection signal is fed back and a set value of brightness of the screen is compared with the detection signal. The magnitude of input power to the light source is controlled so that the comparison value becomes zero.