VERTICAL DEFLECTION CIRCUIT FOR A COLOUR TELEVISION CAMERA HAVING DIFFERENT RASTER SIZES IN ITS CHANNELS

摘要

1386532 Colour television camera; cathoderay tube circuits; saw-tooth current generators ROBERT BOSCH FERNSEHANLAGEN GmbH 9 March 1973 [11 March 1972] 11588/73 Headings H4F H4T and H3T A vertical deflection circuit for a colour television camera in which the pickup tubes, e.g. for red, green and blue, have different scanning raster sizes in order to equalize the tubes signal currents and thus persistence, comprises an operational amplifier 31 for each pickup tubes vertical deflection coil 33 which are supplied at their positive inputs with sawtooth current from a main sawtooth generator (1-16), their inverting inputs being connected via feedback resistors 32 to the junction between the corresponding deflection coil 33 and a resistor 34 whose other end is connected to a constant potential, e.g. ground, all of these resistors 34 having the same temperature coefficients and ohmic values proportional to the desired raster sizes. The sawtooth generator comprises an operational amplifier 9 connected as an integrating amplifier supplied with vertical sync. pulses at input 1, the sawtooth amplitude being adjustable by resistor 6. The resulting sawtooth voltage is fed via voltage divider 15, 16 to the positive inputs at amplifiers 31 and to the ends of potentiometers 22, the other ends of these potentiometers being supplied with the output of inverting operational amplifier 18 which is supplied with the sawtooth voltage. To correct raster skew (i.e. rotation), antiphase outputs derived from amplifiers 9 and 18 may be fed to the horizontal deflection coils. Sawtooth voltages of adjustable amplitude are derived from potentiometers 22 and 23. The zero or central position of the rasters are adjusted by potentiometers 24 to bring them into registration. The relative sizes of the rasters may be adjusted by potentiometers 23, i.e. the red and blue raster sizes may be adjusted relative to the green raster size. RC networks 27, 28, 29 effect parabolic shaping of the sawtooth voltages from potentiometers 22 to enable raster non-linearities to be corrected. Again the red and blue rasters may be corrected relative to the green raster. In addition individual tangential adjustment of the rasters may be effected by the sawtooth voltages from potentiometers 35 which are integrated twice 36-39 and supplied to the inverting inputs of amplifiers 31. The correction voltages derived from potentiometers 22, 23, 24 and 35 are fed to amplifiers 31 via resistors having greater ohmic value than the feedback resistors 32.