| 摘要 |
PURPOSE:To attain a stabler data read/write action by controlling the generation of a synchronizing clock through the frequency-comparison with a crystal oscilla tion signal and switching phase comparison with a servo signal and that with a read data signal when data is written and read, respectively. CONSTITUTION:In the first mode, a switching control part 51 controls a frequency comparison part 52 leading in a crystal oscillation signal 8 from a crystal oscillator becoming a reference oscillator generating a variety of signals in a magnetic disk with the aid of a first mode/normal mode 6 so as to activate said part 52, and transmits the result as signals 2 and 3 to a charge pump 2. When a normal mode signal 7 is inputted, the switching control part 51 activates a phase comparator 53. For writing data, a servo signal 1 is inputted to the phase comparator 53, and the phase of the servo signal 1 is compared with that of a feedback signal 5, thereby controlling the generation of the synchronizing clock 4. For reading data, a data signal 1' and the feedback signal 5 are compared in phase, thereby controlling the generation of the synchronizing clock 4. |
