| 摘要 |
PURPOSE:To shift stably the tracking phase for an arbitrary amount as required, by synthesizing two kinds of error signals having different phase at a specified ratio. CONSTITUTION:A multiplier 14 of an error forming circuit 2 is controlled with a lock point control circuit 4 comprising pilot frequency generating circuit 45 generating a signal in synchronizing with pilot signals in frequencies f1-f4 at each adjacent track, a 1/2 frequency division circuit 41, and switching circuits 42 and 43. After a phase difference signal in response to the track error is outputted from any of the 1st and the 2nd error signal forming circuits 20, 21 in response to the direction of track shift of a head 12, a corresponding DC error voltage is obtained. The DC error voltage shifted by one track is outputted from a circuit 3 the same as the circuit 2 is outputted, and the tape speed is fed back so that the output of an adder 33 of an error phase operating circuit 5 goes to zero and a head 12 is brought to ontrack. Further, in controlling the output of the circuits 2, 3 at coefficients circuits 31, 32, the tracking phase is shifted stably for an arbitrary amount as required. |
