This invention relates to a demodulator circuit for color television signals of PAL system.
As is generally known, in the PAL system, the demodulating axis for one of the two color difference signals, i.e. the R-Y signal, is sent with the phase inverted for each horizontal scanning period (referred to as 1H below). One method used to demodulate such a color difference signal at the correct polarity is to provide a switch which operates at one half of the frequency (refered to as f.sub.H /2 below) of the horizontal frequency (refered to as f.sub.H below) and which is changed over with each 1H. In order to drive this switch, a flip-flop is used for dividing the horizontal pulse, and a f.sub.H line switching pulse is generated. As is also well known, the flip-flop is controlled so as to keep the phase of the f.sub.H /2 line switching signal in correct correspondence to the transmission line information sent by the color synchronizing signal.
In such a circuit, there arises a difficulty in that the PAL switch stops forever in an attempt to control the phase of the f.sub.H /2 line switching pulse, as mentioned above.
USPTO Backgrounds
USPTO Backgrounds