Electric lamp and discharge devices: systems – Cathode ray tube circuits – Cathode-ray deflections circuits
Patent
1988-04-08
1989-01-03
Blum, Theodore M.
Electric lamp and discharge devices: systems
Cathode ray tube circuits
Cathode-ray deflections circuits
H01J 2970, H01J 2976
Patent
active
047959495
ABSTRACT:
In a video display apparatus having an on-screen display feature (OSD), a vertical deflection circuit includes a vertical deflection winding coupled to a DC blocking capacitor. A deflection amplifier responsive to a sawtooth signal is coupled to the vertical deflection winding at an output terminal. A vertical sawtooth voltage generator that generates the sawtooth signal is coupled to an input terminal of the amplifier for driving the output stage at a vertical rate in a sawtooth manner to generate a sawtooth deflection current in the deflection winding. The sawtooth generator includes a capacitor that, during normal operation, is charged in a sawtooth manner via a resistor for developing a sawtooth signal. During a transition interval that follows a user initiated channel selection command, the frequency of the sawtooth signal becomes smaller. To prevent OSD character repositioning, a switch couples a first voltage via the resistor to the capacitor that causes the rate of change of the sawtooth signal and that of the deflection current to become smaller than during normal operation.
REFERENCES:
patent: 4272777 (1981-06-01), Fitzgerald
patent: 4365270 (1982-12-01), Rutishauser
patent: 4544954 (1985-10-01), Chen
patent: 4677484 (1987-06-01), Pitsch et al.
patent: 4694226 (1987-09-01), Wilber
patent: 4731564 (1988-03-01), Pan et al.
A technical manual, "The CTC 85 Color Chasis Technical Manual" dated 1977, pp. 35-44 and the deflection and power supply drawing.
A technical manual "RCA CTC 136 Color Television Basic Service Data" dated 1986, pp. 1-16 to 1-20, the cover sheet and a schematic draw. U.S. Application RCA Docket No. 84,905 entitled, Vertical Deflection Circuit with Service Mode Operation, in the name of J. A. Wilber, the same applicant as in the above captioned patent application and filed concurrently therewith.
Blum Theodore M.
Henig Sammy S.
Laks Joseph J.
Rasmussen Paul J.
RCA Licensing Corporation
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