| 摘要 |
PROBLEM TO BE SOLVED: To make the throughput of a magnetic transfer process higher and the reliability of a transfer signal better by determining the optimum time for cleaning or exchanging of a master disk. SOLUTION: An estimating device 5 estimates the number of particles sticking onto the magnetic disk from the number U(i) of the number of the particles sticking onto a magnetic disk prior to magnetic transfer obtained by a particle counter 3 and the number Y(i) of the particles sticking onto the magnetic disk after the magnetic transfer obtained by a particles counter 4 and outputs a cleaning signal when the estimated value exceeds a previously determined threshold level. The optimum cleaning of the master disk is executed by switching the line input and output by means of a SW 6 and SW 7.
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