| 摘要 |
PURPOSE:To perform a stable tracking control by a simple constitution by controlling a rotating phase of a head and a running speed of a recording medium based on a comparing result of detecting levels of respective envelopes of reproduced angle modulating informations of two heads. CONSTITUTION:Reproduced FM video signals of rotating heads 31, 32 mounted on a rotating body at 180 deg. intervals and having a track width wider than the width of a recording track are amplified by an amplifier and a switch circuit 33 and thereafter become a continuous signal. The reproduced FM video signal taken from the circuit 33 is detected on an envelope by an envelope detector 35, and then supplied to a switch circuit 36. The circuit 36 changes over the envelope detecting signals alternately by a drum pulse from a terminal 34 to sample and hold S/H circuits 37, 38. Output signals (j), (k) of the circuits 37, 38 are supplied to a non-reverse and a reverse input terminals, respectively. According to an output level of an amplifier 40, a rotating phase of the heads 31, 32 and a running speed of a recording medium are controlled and a stable tracking control can be done without using a head driving mechanism.
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