GB1281207A - Penetration color television displays - Google Patents

Abstract

1281207 Converting RCA CORPORATION 10 Sept 1969 [20 Sept 1968] 44610/69 Heading H2F [Also in Divisions H1 and H4] In a colour television receiver using a tube with superimposed layers of different coloured phosphors which are excited according to the energy of the beam from a single electron gun, a staircase colour switching waveform is applied to the screen and an inverse staircase waveform is applied to a grid adjacent the screen to correct raster errors which would otherwise arise to the varying velocity of the beam. In Fig. 2 the V+ supply is connected through a protective relay 50 to the primary winding of a saturable transformer 57, and a circuit is completed when SCR 58 is triggered by a pulse applied through transformer 61. The capacitor 68 is then charged to the maximum level B from the transformer; SCR 58 turns off as the current decreases, and the capacitor 68 discharges through transformer 57 for one line duration (53 microseconds) when the transformer saturates. The transformer and capacitor resonate and the charge on the capacitor reverses, whereupon the transformer desaturates for a further line duration to produce the minimum level R. At the end of this period the SCR 62 is fired by a pulse applied through transformer 65 so that the charge on capacitor 68 can be transferred through transformer 57 to capacitor 64 and dissipated in resistance 63, resulting in the intermediate output level G. The output voltage on capacitor 68 is combined positively and negatively with an EHT voltage derived from a deflection circuit and supplied through resistance 69, to provide the two complementary staircase waveforms shown at opposite ends of the transformer winding.