Rca Inc.

Leslie N Thibodeau

David W Luz

James E Hicks

A retrace pulse voltage is applied to a first flyback transformer winding of a horizontal deflection circuit to develop retrace pulse voltages across other flyback transformer windings. Second and third windings of the flyback transformer are coupled in a series arrangement with a controllable switch across a source of input voltage. A regulator control circuit turns on the SCR at a controllable instant within the trace interval of each deflection cycle to generate input current in the series arrangement. When the retrace pulse voltage is applied to the flyback transformer first winding, the input current begins to decrease in magnitude, commutating off the SCR within the retrace interval. The leakage inductance associated with the series arrangement of flyback transformer second and third windings and the total reflected retrace pulse voltage developed by the two windings determine the instant within retrace that the SCR is commutated off. The third winding is loosely coupled with the first winding, whereas the second winding is tightly coupled with the first winding. By varying the second to third winding turns ratio, the amount of leakage inductance in the series arrangement may be varied without significantly altering the magnitude of the total reflected retrace pulse voltage.

Commutated SCR regulator for a horizontal deflection circuit

A flyback transformer includes a high voltage winding with a first rectifier coupled to the high voltage lead and a second rectifier coupled to the ground return lead. The rectifiers are poled in the same direction to conduct beam current and block the DC current path in the winding during the trace interval. The distributed capacity forms a capacitive voltage divider and developes an intermediate DC voltage in the high voltage winding. The intermediate DC voltage developed at an intermediate AC null terminal of the high voltage winding is selectively adjusted by structure which is selectively capable of adding sufficient distributed capacity to appropriately change the capacitive voltage division ratio.

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Indianapolis, IN, United States of America

Leslie N Thibodeau