Side pincushion correction system

Abstract

A series coupled inductance and active current conducting device are coupled in parallel with a winding of an output transformer of a horizontal deflection generator. Flyback pulses integrated in sawtooth waveforms are combined with a vertical rate parabolic waveform derived from a vertical deflection generator and coupled to a control electrode of the active device for controlling its conduction during each flyback interval at a vertical rate for loading the output transformer and thereby altering the horizontal scanning current in a manner to correct for side pincushion distortion.

What is claimed is: 
     
       1. A side pincushion correction circuit comprising: a line output transformer;   a line deflection winding;   a line deflection generator coupled to said deflection winding and to a first winding of said transformer for inducing energy therein for defining trace and retrace intervals during each line deflection cycle;   a series coupled inductance and active current conducting device coupled in parallel with a second winding of said line transformer;   first waveshaping means coupled to a winding of said transformer for shaping retrace interval waveforms obtained from said winding;   a field rate deflection generator;   second waveshaping means coupled to said field rate generator; and   means for combining said line and field rate waveforms obtained from said first and second waveshaping means and for coupling them to a control electrode of said active current conducting device to conduct for different durations during the line retrace intervals at the field rate for loading said transformer and thereby altering the current in said line rate deflection winding in a manner to compensate for side pincushion distortion.   
     
     
       2. A side pincushion correction circuit according to claim 1 wherein said second winding provides operating voltage for said active device. 
     
     
       3. A side pincushion correction circuit according to claim 2 wherein said first waveshaping means integrates said retrace interval waveforms for forming substantially sawtooth waveforms. 
     
     
       4. A side pincushion correction circuit according to claim 3 wherein said second waveshaping means integrates waveforms obtained from said field rate generator for forming substantially parabolic field rate waveforms for combining with said sawtooth line rate waveforms. 
     
     
       5. A side pincushion correction circuit according to claim 4 wherein said active current conducting device is a thyristor. 
     
     
       6. A side pincushion correction circuit according to claim 5 wherein said field rate deflection generator includes a push-pull output stage obtaining its operating current from rectifying means coupled to a third winding of said line rate output transformer such that said field rate generator additionally loads said line rate scanning current at a field rate in a manner to compensate for side pincushion distortion. 
     
     
       7. A side pincushion distortion correction system comprising: a horizontal deflection generator of the retrace driven type including first and second bidirectional conducting switches, said second switch being coupled to a deflection winding and a winding of an output transformer and said generator supplying energy for said deflection winding during a first interval of each deflection cycle, said first interval including the retrace interval;   a series coupled inductance and active current conducting device direct current coupled in that order between a terminal of a second winding of said transformer and a point of reference potential, retrace pulse energy obtained from said winding supplying operating current to said active device;   first waveshaping means coupled to said second winding and to a control electrode of said active device for enabling conduction of said device during the last portion of said horizontal retrace intervals; and   second waveshaping means coupled to said control electrode for providing a substantially parabolic vertical deflection rate waveform for controlling the conduction time of said active device during said horizontal retrace intervals at said vertical rate such that said first and second transformer windings are loaded by conduction of said active device and scanning current in said deflection winding is altered in a manner to correct for said side pincushion distortion. .Iadd. 8. A television kinescope deflection apparatus comprising:   a vertical deflection generator coupled to a vertical deflection coil for producing vertical scanning current therethrough;   a horizontal deflection generator system for generating horizontal rate current;   a horizontal deflection winding coupled to said horizontal deflection generator for accepting horizontal rate current therefrom for scanning;   impedance means;   controllable switch means;   first coupling means for coupling said impedance means and said controllable switch means in circuit with said deflection winding for defining a path therewith for said horizontal rate current; and   control means coupled to said vertical and to said horizontal deflection generator systems and to said controllable switch means for operating said controllable switch means for controlling its conduction during each flyback interval at a vertical rate for altering the horizontal scanning current in a manner to correct side pincushion distortion. .Iaddend. .Iadd. 9. A television kinescope deflection apparatus according to claim 8 wherein said impedance means comprises inductance means. .Iaddend..Iadd. 10. A television kinescope deflection apparatus according to claim 8 wherein:   said first coupling means couples said impedance means in shunt with said deflection winding; and   said control means operates said controllable switch means for durations during the horizontal retrace interval which are varied in a manner for altering said scanning current in a manner to reduce pincushion distortion. .Iaddend..Iadd. 11. A television kinescope deflection apparatus according to claim 10 wherein said impedance means comprises inductance means and said control means operates said controllable switch means by horizontal rate signals combined with vertical rate parabolic signals. .Iaddend..Iadd. 12. A television kinescope deflection apparatus according to claim 8 wherein said controllable switch means comprises an active current conducting device having a controllable main conduction path and also having a control electrode. .Iaddend..Iadd. 13. A television kinescope deflection apparatus according to claim 12 wherein said active current conducting device is an SCR. .Iaddend. .Iadd. 14. A television kinescope deflection apparatus according to claim 12 wherein said controllable main conduction path of said active current conducting device is serially coupled with said impedance means. .Iaddend..Iadd. 15. A television kinescope deflection apparatus according to claim 14 wherein said serially coupled impedance means and said main conduction path of said active current conducting device are coupled by said first coupling means in parallel with said horizontal deflection winding. .Iaddend..Iadd. 16. A television kinescope deflection apparatus according to claim 15 wherein said first coupling means comprises transformer means. .Iaddend..Iadd. 17. A television kinescope deflection apparatus according to claim 16 wherein said transformer means includes a first winding coupled to said horizontal deflection winding and a second winding coupled to said serially coupled impedance means and active current conducting device main conduction path. .Iaddend..Iadd. 18. A television kinescope deflection apparatus according to claim 16 wherein said transformer means includes a first winding coupled in parallel with said horizontal deflection winding and a second winding coupled across said serial combination of said impedance means and said main conduction path of said active current controlling means. .Iaddend. .Iadd. 19. A television kinescope deflection apparatus according to claim 8 wherein said control means operates said controllable switch means during the second half of each retrace interval. .Iaddend..Iadd. 20. A television kinescope deflection apparatus according to claim 8 wherein said control means varies the conduction time of said controllable switch means during the horizontal retrace interval at the vertical rate. .Iaddend..Iadd. 21. A television kinescope deflection apparatus according to claim 20 wherein said impedance means is coupled in serial combination with said controllable switch means, and said serial combination is coupled in parallel with said horizontal deflection winding. .Iaddend. .Iadd. 22. A television kinescope deflection apparatus according to claim 8 wherein said control means comprises:   parabola waveshaping means coupled to the vertical deflection generator for generating a parabolic signal at the vertical deflection rate;   horizontal rate waveshaping means coupled to said horizontal deflection generator system for generating a horizontal rate signal having a maximum during said horizontal retrace pulse period; and   modulating means coupled to said parabola waveshaping means and to said horizontal rate waveshaping means for generating horizontal rate pulses modulated by said parabola signal. .Iaddend. .Iadd. 23. A television kinescope deflection apparatus comprising:   a vertical deflection generator coupled to a vertical deflection coil for producing vertical scanning current therethrough;   a horizontal deflection generator system for generating horizontal rate current;   a horizontal deflection winding coupled to said horizontal deflection generator for accepting horizontal rate current therefrom for scanning;   impedance means;   controllable switch means;   means coupling said impedance means and said controllable switch means in circuit with said deflection winding for defining a path for said horizontal rate current;   control means coupled to said vertical and to said horizontal deflection generator systems and to said controllable switch means for operating said controllable switch means at a time during the horizontal retrace interval which is progressively advanced during the first half of the vertical scan interval and which is progressively retarded during the second half of the vertical scan interval for altering said scanning current in a manner to reduce pincushion distortion. .Iaddend. .Iadd. 24. A television kinescope deflection apparatus according to claim 23 wherein said impedance means is coupled in shunt with said horizontal deflection winding. .Iaddend..Iadd. 25. A television kinescope deflection apparatus according to claim 23 wherein said impedance means is serially coupled with said controllable switch means. .Iaddend..Iadd. 26. A television kinescope deflection apparatus according to claim 25 wherein said impedance means and serially coupled controllable switch means are coupled in shunt with said horizontal deflection winding. .Iaddend. .Iadd. 27. A pincushion correction circuit for a kinescope deflection apparatus including horizontal and vertical deflection generator systems, comprising:   a horizontal deflection winding coupled to the horizontal deflection generator system for accepting scanning current therefrom;   an impedance circuit including an inductor;   first coupling means for coupling said impedance circuit with said deflection winding;   controllable switch means including a control electrode and a controlled current path serially coupled with said impedance circuit; and   control means coupled to the horizontal and vertical deflection generator and to said control electrode for operating said controllable switch means at a time during the second half of the horizontal retrace interval which time is progressively advanced during a first portion of the vertical scan interval and which is progressively retarded during a second portion of the vertical scan interval for altering said scanning current in a manner to reduce pincushion distortion. .Iaddend. .Iadd. 28. A pincushion correction circuit according to claim 27 wherein said first coupling means couples said impedance circuit in parallel with said deflection winding. .Iaddend..Iadd. 29. A pincushion correction circuit according to claim 28 wherein said first coupling means comprises;   transformer means having a primary winding and a secondary winding; and   wherein said primary winding is coupled with said deflection winding and said secondary winding is coupled with said impedance circuit. .Iaddend..Iadd. 30. A pincushion correction circuit according to claim 27 wherein said controllable switch means comprises an SCR. .Iaddend..Iadd. 31. A pincushion correction circuit according to claim 30 wherein said controlled current path of said uncontrollable switch comprises the anode-to-cathode conducting path of said SCR; and   said control electrode of said controllable switch means comprises the gate of said SCR. .Iaddend.