| 摘要 |
PURPOSE:To generate accurate cylinder pulse resistant to noise by outputting cylinder pulse by the output of a timer and preventing the resetting of the timer by noise while timer output exists. CONSTITUTION:In a magnetic disk device having a servo track system, a speed signal 6 that indicates the moving speed of a servo head is inputted to an A/D converter 1, and a ROM 2 outputs a timer value corresponding to a digital speed signal. A timer circuit 3 makes a timer output 7 an H level for a time corresponding to the input timer value from the leading of a trigger signal 9, and a one shot circuit 4 output cylinder pulse 10 at the leading of the timer output 7. A zero crossing detecting circuit 11 generates a pulse 12 at every time when a position signal 8 indicating the position of the servo head passes 0V, and an OR gate 5 prohibits the inputting to the timer circuit 3 while the output of the timer circuit exists. Thus, no influence is caused even when the position signal 8 passes 0V due to noise, etc., even when zero cross pulse 12 is inputted.
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