CORRECTION CIRCUIT FOR PINCUSHION DISTORTION

摘要

PURPOSE:To eliminate virtually the pincushion distortion and to improve the reliability of a distortion compensating circuit, by storing previously the compensating circuit, by storing previously the compensating information of the pincushion distortion in a digital memory and producing a compensating signal based on th correcting information to obtain an optional correction waveform. CONSTITUTION:The correcting information based on which a pincushion correction signal is digitally stored in a digital memory 40 and then read out to a D/A converter 41 to be converted into an analog value. Thus the parabola voltage VP is produced. The voltage VP is set at a value obtained by carrying out the sampling to the frequency of a horizontal synchronizing signal and then applied to a multiplying or modulating circuit 22 to be superposed on the vertical sawtooth wave voltage VS applied to the circuit 22. Then the current ID flowing to a vertical deflecting coil 20 is modulated with an optional correcting waveform and through the circuit 22. Thus the pincushion distortion can be virtually eliminated.