Electric lamp and discharge devices: systems – Cathode ray tube circuits – Cathode-ray deflections circuits
Patent
1986-08-29
1987-09-15
Blum, Theodore M.
Electric lamp and discharge devices: systems
Cathode ray tube circuits
Cathode-ray deflections circuits
358 10, 315397, 315389, H01J 2970, H04N 1702
Patent
active
046942262
ABSTRACT:
In a video display apparatus having a service mode of operation, a vertical deflection circuit includes a vertical deflection winding coupled to a DC blocking capacitor. An output stage includes first and second output amplifiers coupled to the vertical deflection winding in a push-pull arrangement at an output terminal. A vertical sawtooth voltage generator is coupled to a driver stage via an error amplifier that provides both AC and DC negative feedback for driving the output stage at a vertical rate in a sawtooth manner to generate a sawtooth deflection current in the deflection winding and for establishing a DC operating voltage level at the output terminal that charges the DC blocking capacitor. A service mode switching circuit is coupled to the driver stage for asserting the service mode of operation by maintaining the first output amplifier in cutoff and the second output amplifier in conduction to discharge the DC blocking capacitor and disable the generation of the sawtooth deflection current.
REFERENCES:
patent: 3461225 (1969-08-01), Crookshanks et al.
patent: 3525801 (1970-08-01), Willis
patent: 3715493 (1973-02-01), Allen
patent: 3820155 (1974-06-01), Neal
patent: 4123776 (1978-10-01), Cochran et al.
patent: 4130829 (1978-12-01), Kam et al.
patent: 4272777 (1981-06-01), Fitzgerald
patent: 4309718 (1982-01-01), Johnson
U.S. patent application Ser. No. 862,287, filed May 12, 1986, entitled Service Switch for Video Display Apparatus, H. Pan et al.
"The CTC 85 Color Chassis Technical Manual", dated 1977, pp. 35-44 and the Deflection and Power Supply Schematic Drawing.
"RCA CTC136 Color Television Basic Service Date", dated 1986, and published prior to the filing date of applicant Wilber's U.S. patent application.
Blum Theodore M.
Cain David
Laks Joseph J.
Rasmussen Paul J.
RCA Corporation
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