Spot eliminating circuit of an image display device
Patent 6046552 Issued on April 4, 2000. Estimated Expiration Date: 
December 30, 2017. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
December 30, 2017. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesCRT Spot suppression circuit Blanking circuit for use in a display apparatus which has a cathode-ray tube Video display apparatus with kinescope spot burn protection circuit Spot killer circuit having blanking function Spot elimination circuit for a cathode ray tube Patent #: 5677730 InventorAssigneeApplicationNo. 000866 filed on 12/30/1997US Classes:315/380, Control only at turn-on or turnoff of circuit315/381, Circuits control grid-cathode circuit of tube315/384, Ray blanking348/173CATHODE-RAY TUBE BURN-IN PREVENTIONExaminersPrimary: Westin, Edward P.Assistant: Wells, Nikita Attorney, Agent or FirmForeign Patent References
International ClassesH01J 029/52G09G 001/04 Foreign Application Priority Data1996-12-30 KRAbstractA spot is prevented from occurring on the center portion of a cathode ray tube when electric power is turned off by using a voltage charged in a capacitor which are used for outputting a vertical blanking signal in a vertical blanking signal generating circuit of an image display device for displaying an image in use of the cathode ray tube. The present invention is provided with a discharge cut-off element between a negative electric power source and the capacitor for outputting a vertical blanking signal and a discharging element for discharging a charged voltage of the capacitor to the ground. The present invention prevents a charged voltage ofthe capacitor from being discharged until thermoelectrons are not emitted from the cathode so as to supply a negative charged voltage to the first grid of the cathode ray tube continuously, so that a spot is prevented from occurring. All the negative voltage charged in the capacitor is discharged when a time period has elapsed during which occurrence of a spot is blocked. | |
