Synchronized switched-mode power supply unit with power line isolated horizontal output stage in television receivers

摘要

1. Synchronised switched-mode power supply with a mains isolated horizontal output circuit in television receivers for generating a sawtooth current, only one transformer being provided for electric isolation between mains and chassis side and the switched-modo power supply being supplied with an unregulated direct voltage, including a mains-side freely starting regulating loop for controlling the main current path, a regulating switch via which the unregulated direct voltage feeds the primary winding n1 of the transformer, a first chassis-side winding n2 via which energy is recovered for the horizontal output circuit during the retrace interval, this first chassis-side winding n2 being loosely coupled to the primary winding n1 and being electrically isolated from the mains side, a winding n4 via which the regulating information is obtained for correcting the lead time of the regulating switch, and a winding n3 via which low-voltage voltages are obtained for the low-frequency stages, the horizontal oscillator and the small-signal stages, characterised by a combination of the two following features : a) the winding n4 , via which, in addition, the regulating loop (2) is synchronised, is tightly coupled to the first chassis-side winding n2 ; b) the winding n3 is tightly coupled to the primary winding n1 and loosely coupled to the first chassis side winding n2 .