| 摘要 |
PURPOSE:To generate a head switching pulse by the detection signal of the rotation detecting means below, by providing a set of the rotation detecting means on the disc in the switching circuit for plural rotary head output signals. CONSTITUTION:The detection pulse from single rotation detector 31 is applied to the gate-off control terminal of the first counter circuit 34 through amplifying circuit 32 and delay circuit 33 to stop the count operation of clock pulse Cp, and contents are cleared by the next pulse, and counting is started by the next pulse after this pulse. The output of the delay circuit is applied to the gate-on terminal of the second counter circuit 35 also, and clock pulse 2Cp is counted by the output of this delay circuit. The output of the delay circuit is applied to the control terminal of memory circuit 36 also to store count data of counter circuit 34, and it is applied to one terminal of comparing circuit 37. The output of counter circuit 35 is applied to the other terminal of comparing circuit 37, and the output of this comparing circuit is obtained at output terminal 38. |
