| 摘要 |
PURPOSE: A method for adjusting an index signal of a servo track writer is provided to adjust the optimum frequency of an index signal substantially and accurately. CONSTITUTION: A reference clock signal(CK) is inputted at a clock terminal of a 24-bit counter(21). An index signal reproduced a testing servo data recorded in a hard disk drive is inputted at a reset terminal of the 24-bit counter(21). The 24-bit counter(21) continuously measures a period of the index signal. Data A0,...A23 from the 24-bit counter(21) are inputted in a 24-bit digital comparator(22), and compared with reference period data(PD, B0,...,B3). If a period of the index signal is more than the reference period, the output(A>B) of the digital comparator(22) is converted into a high state. The output(A>B) of the digital comparator(22) is inputted at one terminal of a programmable delay element(23) and a NAND gate(24). The programmable delay element(23) outputs a signal of high state after a set time is passed by delay data(DD) from a state of the delay element(23) is high. If inputted two signals are high state, the NAND gate(24) inputs a low state signal at a reset terminal(RST) of a 8-bit counter(25).
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