Side pincushion correction circuit
AssigneeSony Corporation
InventorsSeiichi Ogawa, Yoshiaki Ohgawara, Kenichi Ohtsuka
Life of this patent
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Abstract
A side pincushion distortion correction circuit has an impedance circuit connected in series with the deflection coil in a television receiver. A controllable switch connected in parallel with the impedance circuit is operated by a switching signal, the phase of which is modulated by a combination of a parabolic signal at the vertical rate and a control signal corresponding to the brightness of a reproduced picture on the screen of the television receiver in order to maintain proper correction of side pincushion distortion despite variations in the brightness of a picture reproduced on the cathode ray tube of the television receiver.
Claims16
A side pincushion distortion correction circuit for a cathode ray tube deflection apparatus including a horizontal deflection generator for generating a horizontal scanning current and a horizontal pulse during a retrace interval thereof and a vertical deflection generator for generating a vertical scanning current during a vertical scan interval and a parabolic wave signal synchronized therewith, comprising,
- a horizontal deflection winding coupled to said horizontal deflection generator for accepting said horizontal scanning current;
- an impedance circuit connected in series with said horizontal deflection winding;
- controllable switch means including a controllable switch having a control electrode and a controlled current path connected in parallel with said impedance circuit;
- switching signal generating means for generating a switching signal responsive to said horizontal pulse;
- means for modulating the phase of said switching signal by said parabolic wave signal at the vertical rate;
- means for supplying said switching signal to said control electrode of said controllable switch for operating said controllable switch during the latter half of said horizontal retrace interval;
- means for progressively advancing said phase of said switching signal during a first portion of the vertical scan interval and for progressively retarding said phase during a second portion of the vertical scan interval for altering said scanning current in a manner to reduce pincushion distortion;
- means for generating a brightness signal corresponding to the brightness of a reproduced picture;
- and
- means for further modulating said phase of said switching signal in dependence on said brightness signal.
A side pincushion distortion correction circuit for a cathode ray tube deflection circuit capable of displaying a picture having varying brightness of the type which produces a horizontal deflection signal including a retrace portion for application to a horizontal deflection winding and a vertical deflection signal, comprising:
- an impedance connected in series with said horizontal deflection winding operative to limit current through said horizontal deflection winding;
- controllable switching means responsive to a switching signal for bypassing said impedance;
- switching signal generating means for generating said switching signal during said retrace portion;
- means for producing a brightness signal which is variable in proportion to said brightness;
- means for producing a parabolic signal in synchronism with said vertical deflection signal;
- means for producing a sawtooth signal at the same rate as said horizontal deflection signal;
- and
- said switching signal generating means being responsive to said brightness signal, said parabolic signal and said sawtooth signal to generate said switching signal at a time which is variable in dependence thereon.
Dependencies are inferred from the claim text.