DISPOSICION DE CIRCUITO PARA SER USADA EN UN RECEPTOR DE TELEVISION PARA LA CONVERGENCIA RADIAL DINAMICA DE, AL ME- NOS, DOS HACES ELECTRONICOS.

摘要

1,175,221. Cathode-ray tube circuits. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 16 Feb., 1967 [19 Feb., 1966], No. 7525/67. Heading H4T. In an arrangement providing dynamic convergence in the field scan direction of the R (red), G (green) and B (blue) beams of a colour display cathode ray tube a voltage having a parabolic waveform is developed across a potentiometer 7 (Fig. 1) in the anode circuit of the field output valve 1 and a voltage having a sawtooth waveform is developed via a winding 4 on the field output transformer 3. The overall amplitude of the resultant parabolic current in the convergence coils R and G is adjusted by potentiometer 7, and the relative amplitude is adjusted by potentiometer 14. In the case of the sawtooth voltage the direction and overall amplitude of the resultant current in the coils R and G is adjusted by potentiometer 8 whist the relative direction and amplitude is adjusted by mechanically coupled differentially operating respective potentiometers 10 and 11. For the blue convergence coil B the amplitude and direction of the parabolic current is adjusted by potentiometer 15 and potentiometer 9 allows a similar adjustment in respect of the sawtooth current. In order to ensure that a sawtooth current flows in the deflection coils 6 (connected to winding 5 on the transformer), that a pure parabolic voltage is produced across potentiometer 7 and that winding 4 operates virtually as a sawtooth voltage source a matching circuit comprising R4, C4 is employed to compensate for the load presented by the convergence coils and potentiometers. The method of determining the values of R4 and C4 in terms of such load is given and a non-mathematical analysis of the operation of the circuit of Fig. 1 is given with reference to equivalent circuit diagrams (Fig. 2 to 9, not shown). The parabolic voltage may be derived from a potentiometer replacing resistor 8 in the cathode circuit of valve 1 instead of from potentiometer 7, the connections to the coils R and G being inverted since the cathode voltage is of opposite polarity to the anode voltage and valve 1 may be replaced by a transistor.