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:
Apr. 30, 1985
Filed:
May. 10, 1982
Kunisuke Kasagi, Mobara, JP;
Machio Kawashima, Mobara, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A color television receiver includes a color picture tube having three electron guns including cathodes and heaters therefor, respectively, and an automatic cutoff adjusting circuit for adding a reference voltage signal substantially at a black level to a luminance signal during an interval beginning substantially at the end of a vertical blanking period, and for detecting cathode currents flowing toward the cathodes during the above-described interval to control cathode voltages for the cathodes for keeping the cathode currents at a predetermined level by way of feedback of voltages proportional to the cathode currents. There is provided a circuit for applying a positive voltage to each of the heaters during the above-described interval to reduce a potential difference between the heater and corresponding one of the cathodes to thereby lower a leakage current flowing between the cathode and the heater.