CLOCK DETECTOR FOR ROTARY HEAD TYPE RECORDER

摘要

PURPOSE:To eliminate the wrong detection with the joint recording by switching a head at the middle of each track in a reproduction mode preceding a record mode and at the same time detecting the state of a reproduction output synchronously with the head switching to detect the clock generation. CONSTITUTION:In a reproduction mode preceding a record mode next to a joint record mode, switch circuits 31 and 32 are switched to the side of a terminal PB by the signal MRP sent from a timing signal generating circuit 30. Then the reproduction outputs given from rotary heads 25A and 25B are supplied to a head switch circuit 41. The circuit 41 is switched by the switch signal PAB given from the circuit 30. The signal PAB obtained in a reproduction mode has a double frequency as much as the switch signal obtained in a record mode. The outputs of rotary heads 25A and 25B are switched every half revolution. This switching time point is set at about the middle of the scan period of heads 25A and 25B respectively. That is, the reproduction outputs of heads 25A and 25B are obtained from the circuit 41 in the first half and the second half of each scan period respectively.