Synchronizing circuit and sawtooth generator for the field deflection in a picture display device

摘要

A synchronizing circuit and a sawtooth generator for the field deflection in a picture display device in which the sawtooth-shaped signal generated by the sawtooth generator has a retrace whose duration is switchable between a short and a longer duration. In a first use this switchover is used for eliminating the interlacing upon reception of interlaced signals, while the difference between the two durations is equal to half a line period and the switchover is effected at the picture frequency. In a second use a memory circuit is used which is an auxiliary circuit for the field synchronization, in which the shorter duration of the retrace period is switched over to in the absence of a plurality of successive incoming field synchronizing pulses, which plurality is not higher than a predetermined value.