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:
Aug. 30, 2005
Filed:
Apr. 19, 2001
Taketoshi Hibi, Tokyo, JP;
Taketoshi Hibi, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
In a beam current limiting circuit for a video projector, an average current is limited under closed loop control containing an anode current detection circuit. On the other hand, a cathode current detection circuitcomprises a first resistor and a second resistor in series to a cathode current circuit and detects a cutoff current at the voltage across the first resistor and an average current at the voltage across the second resistor. An offset addition circuitis provided for correcting the detection value of the average current based on the maximum value of detected cathode current, and beam current is limited. Further, meansfor detecting time change of anode current is provided and if the current value does not change for a long time, the beam current is limited to a smaller value.