Image Number 4 for United States Patent #4272705.
A cathode ray tube (CRT) in a video display utilizes an anti-ringing system for minimizing beam scanning distortion at the start of trace. This distortion is due to velocity modulation of the scanning beam caused by high frequency, resonant energy in the inductances of the linearity and width coils and the electromagnetic deflection yoke, all of which are in series. The first half of beam scan cycle is accomplished by the conduction of the damper diode while operation of the horizontal output transistor provides beam deflection current for the second half of horizontal sweep. A low impedance is introduced in the circuit for a short period during the start of damper diode current conduction by means of a voltage biasing diode network. This low impedance dampens out high frequency resonant ringing without degrading video display performance by excessive resistive loading.