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US 5,475,286 AGranted
Deflection waveform correction circuit
AssigneeThomson Consumer Electronics, Inc.
InventorsDavid R. Jackson, Kenneth J. Helfrich
Life of this patent
Estimating the term…
Abstract
A deflection apparatus comprises a deflection amplifier coupled to a deflection waveform modulation circuit such as a diode modulator. A source for generating a modulation signal. The modulation signal comprises a symmetrical periodic AC component having equal first and second portions of a trace period. A feedback amplifier alters the amplitude of a first portion of the trace period relative to a second portion of the trace period to render the AC component asymmetrical. The asymmetrical AC component is coupled to the deflection waveform modulation circuit for deflection waveform modulation.
Claims19
A deflection apparatus comprising:
- a horizontal deflection amplifier and a vertical deflection amplifier for generating deflection currents in horizontal and vertical deflection coils respectively, to form a scanned raster having asymmetrical pincushion distortion;
- a deflection waveform modulation circuit having a modulation input and having an output coupled to said horizontal deflection amplifier and said horizontal deflection coil to generate a corrective current therein;
- a source of a vertical frequency modulation signal, having a period comprising a first interval with a first waveform shape and a second interval with a second waveform shape where said first waveform and said second waveform are symmetrically shaped and of equal magnitude;
- and,
- means coupled to said source for altering the shape of at least one of said first and second waveform shapes to generate an asymmetrically shaped modulation signal coupled to said input of said waveform modulation circuit to substantially correct said raster.
2 more elements
A deflection apparatus for a video display comprising:
- a horizontal deflection amplifier;
- a deflection waveform modulation circuit coupled to said deflection amplifier for deflection waveform correction;
- a source of a vertical rate modulation signal, having a waveform shape occurring substantially between vertical retrace intervals;
- and,
- an amplifier coupled to said source for amplifying said modulation signal, said amplifier having a feedback network for generating at an output, a signal having a waveform shape asymmetrically occurring between said vertical retrace intervals, said signal being coupled to said waveform modulation circuit for correction of an asymmetrical distortion in said display.
2 more elements
A video display apparatus comprising:
- a horizontal deflection coil;
- a vertical deflection coil;
- a horizontal deflection amplifier and a vertical deflection amplifier generating deflection current in said horizontal and said vertical deflection coils respectively and producing a scanned raster having asymmetrical east west pincushion distortion;
- a deflection waveform modulation circuit having an input and having an output coupled to said horizontal deflection coil and generating a corrective current therein;
- a source of a vertical frequency modulation signal having a period comprising a first interval with a first waveform shape and a second interval with a second waveform shape, said first waveform and said second waveform having substantially similar shape and magnitude;
- and,
- a network having a non-linear transfer characteristic coupled to said source for altering said shape of at least one of said first and second waveform shapes generating a dissimilarly shaped modulation signal, said non-linear transfer characteristic being generated by a diode having a biasing voltage, insufficient for conduction, determined by a resistive potential divider, said dissimilarly shaped modulation signal being coupled to said input of said deflection waveform modulation circuit, substantially correcting said raster distortion.
4 more elements
A deflection apparatus for a video display comprising:
- a horizontal deflection amplifier;
- a deflection waveform modulation circuit coupled to said deflection amplifier for deflection waveform correction;
- a source of a vertical rate parabolic modulation signal, having waveform cusps occurring during a vertical retrace period;
- and,
- an amplifier coupled to said source for amplifying said modulation signal, said amplifier having a negative feedback network having a frequency selective transfer characteristic and generating said modulation signal as an output, shifted in time, said waveform cusps occurring partially during said vertical retrace interval and a trace interval, said output signal being coupled to said waveform modulation circuit for correction of an asymmetrical distortion in said display.
2 more elements
A deflection apparatus for a video display comprising:
- a deflection amplifier;
- a deflection waveform modulation circuit coupled to
- said deflection amplifier;
- a source for generating a vertical rate parabolic modulation signal;
- and,
- a second amplifier coupled to said source for amplifying said modulation signal, said amplifier having a negative feedback network comprising a series coupled combination of a resistor and a capacitor, said combination being coupled in parallel with a second resistor, said network generating an asymmetric vertical rate parabolic modulation signal, said asymmetric modulation signal being coupled to said waveform modulation circuit for correction of an asymmetric distortion in said display.
3 more elements
Dependencies are inferred from the claim text.