| 摘要 |
PROBLEM TO BE SOLVED: To enable preventing dispersion of the number of rotations for each spindle motor when the prescribed drive voltage is applied without using an FG signal for detecting rotation of the spindle motor rotating an optical disk, and to enable shortening a rise time of rotation of the spindle motor. SOLUTION: The optical disk is rotated by applying constant drive voltage to the spindle motor, the length of the longest bit in an EFM signal on information data reproduced from the optical disk is measured, based on a reference clock, the number of rotations of the optical disk is calculated from the measured length of the longest bit, gain of a motor drive IC is set in accordance with the calculated number of rotations of the optical disk, based on correlation of drive voltage of the spindle motor and the number of rotations of the optical disk, at the time of rise of rotation of the spindle motor, the largest drive voltage is applied to the spindle motor to rotate the spindle motor. COPYRIGHT: (C)2007,JPO&INPIT
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