| 摘要 |
PURPOSE:To decide on whether intervals of servo patterns on a magnetic disk are normal or not without reference to fluctuation in turning speed, by deciding on whether a writing interval between two patterns is normal or not on the basis of whether the difference between a reference voltage and a voltage to be detected is a value within the prescribed range or not. CONSTITUTION:In a normal disk rotation state, servo patterns written on one track are read out by a heat, and a VCO in a PLL is oscillated to the read signal to generate clock pulses at intervals obtained by dividing the time for one readout-speed turn of the disk by a specific integer accurately and equally. On the basis of this clock, the time from the pattern pulse generation point by the read signal of some servo pattern to the pattern pulse generation point corresponding to a next servo pattern is measured. Then, the properiety of writing intervals between respective patterns is decided on according to whether the difference between a reference voltage and a voltage to be detected is less than a value in the prescirbed range or not. |
