Television – Cathode-ray tube display excessive voltage control – With disabling
Reexamination Certificate
2005-01-25
2005-01-25
Miller, John (Department: 2614)
Television
Cathode-ray tube display excessive voltage control
With disabling
C315S382100, C315S411000
Reexamination Certificate
active
06847404
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 (100) having an anode (112) and a cathode (102) for generating and controlling beam currents in the display device, a protection circuit comprising: a source of video signals (36); a driver circuit (40) coupled to the source of video signals and the cathode (102), 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 (X1) coupled to the anode (112) for providing high voltage accelerating potential in the display device; and a shutdown circuit (44) 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.
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Integrated Circuits, Data Sheet TDA6120Q, Video Output Amplifier Aug. 27, 1997, Philips, pp. 1-16.
Griepentrog Dal Frank
Jackson David Ross
Kiel Paul P.
Miller John
Thomson Licensing S.A.
Tripoli Joseph S.
Yenke Brian
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