Charge controlled raster correction circuit

摘要

An East-West switching transistor is coupled between a flyback transformer primary winding and a horizontal deflection output transistor circuit to control retrace energy to obtain an East-West modulation of the deflection current amplitude as required for East-West pincushion raster correction. A pair of series coupled first and second capacitors forming a capacitive voltage divider are coupled to a retrace resonant circuit that includes the deflection winding via a sampling switch, during a first half of a retrace interval, to produce a first ramping capacitor voltage in the first capacitor from a portion of a retrace pulse voltage. The first capacitor is coupled to an East-West pincushion raster correction current source for producing a second ramping capacitor voltage in the first capacitor that ramps in an opposite direction. A comparator is responsive to the capacitor voltage for controlling a conduction interval of the East-West switching transistor.