PURPOSE: To generate phase shift signal without using externally mounted components, and without causing error in phase shift difference through the digital operation of two sets of FF.
CONSTITUTION: The outputs Q,Q' of FF 11,12 are respectively fed to other S,R. The pulse P0 of duty factor 50% having twice the self-running frequency of the carrier chrominance signal is oscillated from VCO 13 and is fed to CK of FF12 with FF11 and inversion 14. The burst signal is fed from the gate 15 and VCO is controlled with phase comparison 16 for the outputs Q11 and Q11'. Synchronous detection 17 is made by taking Q11,Q11' and Q12,Q12' as reference. Further, the burst signal 15 is made to phase comparison 18 with Q12,Q12'. With this constitution, Q11,Q11' are inverted with every leading of the pulse P0, Q12,Q12' are inverted with every trailing, Q11 to Q12' are equals to the burst signal, i.e., the carrier frequency of the chrominance signal, and Q11,Q11' and Q12,Q12' produce the phase difference of 90°. Chrominance signal is synchronous-detected with Q11,Q11' and red color difference signal is demodulated, and blue color difference signal is demodulated with Q12,Q12'. Further, ACC and color killer is made by using the output of comparison 18.
AKAZAWA SUSUMU
OKADA TAKAFUMI
YAMAKOSHI AKIRA
| JPS5121294A | 1976-02-20 |
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