A circuit arrangement for generating high tensions by retificacao of pulses return line or retraco horizontal to the anode accelerator (ultor) and at least one additional electrode of the valveThe image of a television receiver

摘要

1,113,353. Cathode-ray tube circuits. RADIO CORPORATION OF AMERICA. 3 Aug., 1965 [31 Aug., 1964], No. 33253/65. Heading H4T. [Also in Division H2] A regulating valve 80 connected in shunt with the E.H.T. supply (derived by rectification of the fly-back pulses across line transformer 50) to the ultor electrode 29 of a colour picture tube 20 operates to oppose both long term variations and variations at field frequency in the ultor potential, the latter variations arising e.g. from interaction between the line and field deflection circuitry in the operation of known " pincushion " correction circuits 43. Correction for the long term variations, which are caused by the beam current demand of tube 20 following variations in the D.C. component of the luminance signal and are manifest as corresponding variations in the " boost " voltage, is effected by supplying the D.C. component (from terminal LD) and the " boost " voltage (from terminal BB) to the control grid of valve 80 to vary its conductance in a compensatory manner whilst for compensation of the field frequency variations the conductance is further controlled by a voltage, termed the " boostedboost " voltage, in which such variations occur, this voltage, derived by rectification (diode 90) of line fly-back pulses to provide operating potentials for the screen-grid electrodes 25 (R, G, B), being supplied to the grid of valve 80 via a capacitor 97 which, together with a capacitor 95 and resistor 93 serves to attenuate variations at line and higher (e.g. video) frequencies.