Television apparatus with supplementary kinescope blanking and spot burn protection circuitry

Abstract

Supplementary grid blanking and spot burn protection are provided in a receiver/monitor (10) by a grid bias control circuit (50) including a blanking signal generator (60) that produces a blanking output signal (S1) devoid of any picture representative component whenever a vertical blanking signal (VB) or a horizontal blanking signal (HB) is present. A capacitor (C1) strips DC from the blanking signal and the resultant signal (S2) is applied to a modulation input (84) of a grid bias generator to produce an output grid bias reference voltage (Vr) modulated by the AC component of the blanking signal. The reference voltage (Vr) is coupled via a spot burn protection circuit (100) and a grid coupling circuit (120) to the control grids of three projection kinescopes (16, 18, 20). Distortions which may tend to appear in the grid blanking pulses are corrected by a high frequency correction circuit (140) coupled between an output (66) of the composite blanking generator (60) and an input (122) of the grid coupling circuit (120).

Dependencies are inferred from the claim text.