Video display protection circuit
US6847404B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 29, 1999 |
| Grant date | Jan 25, 2005 |
| Priority date | — |
| Expiry date | Sep 29, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N3/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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 circui…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.