Dynamic focus voltage amplitude controller

摘要

A dynamic focus voltage generator includes a source of a flyback input signal (VFB) at a horizontal deflection frequency . A double integrator (U9A, C33, C34) is responsive to the input signal for generating a parabolic periodic signal (VU9A). An amplitude detector (D19, D20) is responsive to the parabolic periodic signal for generating a contol signal (V56) that is indicative of an amplitude of the parabolic periodic signal. A comparator (U7A) is responsive to a signal at a reference level (between R50, R51) and to the control signal and coupled to the double integrator for regulating an amplitude of the parabolic periodic signal in a gain control negative feedback manner. A non-linear network (D18, R53) is responsive to the parabolic periodic signal for producing a bathtub shaped output signal (V5') that is coupled to a focus electrode of a cathode ray tube. <IMAGE>