| 摘要 |
PURPOSE:To prevent a color change arising on the upper part of an output picture on a screen even if an input signal is switched and to quickly cope with the switching of the input signal by using a write clock generator with an instantaneously locked burst control oscillator for a television synchronization converter. CONSTITUTION:A write clock generator circuit 30 used by the television synchronization converter includes a start pulse generator 31 to generate one start pulse during one horizontal scan period, and the start pulse instantaneously locks the instantaneously locked oscillator 36. It is constituted of two monostable multivibrators 36-1 and 36-2, and can obtain continuous waves completely locked with a burst phase accordingly. In order to follow the frequency fluctuation of an input burst, a phase comparator 43 compares a start pulse with a signal obtained by counting down the output of the oscillator 36, and an error signal obtained in such a way forms a negative feedback loop to change the pulse width of the multivibrator.
|
