| 摘要 |
PURPOSE:To switch plural heads with high accuracy without reference to the rotating speed of a rotary drum by setting the number that a pulse counting means counts in conformity with the number of rotary heads and their fitting positions. CONSTITUTION:A drum PG signal outputted by a FG detector 12 is inputted to the data input terminal of a shift register 17 and a drum FG signal outputted by a FG amplifier 9 is inputted to the clock input terminal of the register 17 respectively. The register 17 outputs its output signal to a gate circuit 17 every time the number of pulses corresponding to the playback period of respective heads 3a-3d is inputted while the output is delayed by the number of pulses equivalent to a time difference corresponding to the fitting position shift between a pulse generator 8 and rotary heads 3a and 3b, and 3c and 3d. The circuit 18 outputs a switching signal for a switch 5, which switches the outputs of the heads 3a-3d and outputs it to a terminal 6 as a continuous signal.
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