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:
Jan. 25, 2005
Filed:
Sep. 29, 1999
David Ross Jackson, Indianapolis, IN (US);
Dal Frank Griepentrog, Indianapolis, IN (US);
David Ross Jackson, Indianapolis, IN (US);
Dal Frank Griepentrog, Indianapolis, IN (US);
Thomson Licensing S.A., Boulogne, FR;
Abstract
An apparatus and a method for protecting a video display device, having an anode and a cathode, against excessive beam current conditions. In particular, the present invention protects the video display device against zero-biasing of the device, wherein the cathode driver circuit is supplied by a plurality of power supplies and the loss of anyone of the power supplies causes zero-biasing of the cathode. The invention provides, in a video display device () having an anode () and a cathode () for generating and controlling beam currents in the display device, a protection circuit comprising: a source of video signals (); a driver circuit () coupled to the source of video signals and the cathode (), the driver circuit coupled to a driver circuit power supply (+12V,+215V), the driver circuit causing a cathode voltage to be generated on the cathode in response to the video signals and the driver circuit power supply; a high voltage power supply (X) coupled to the anode () for providing high voltage accelerating potential in the display device; and a shutdown circuit () coupled to the driver circuit power supply and the high voltage power supply, the shutdown circuit disabling the high voltage power supply if the driver circuit power supply voltage decreases below a threshold level.