| 摘要 |
PROBLEM TO BE SOLVED: To form a wobble or a pit with a prescribed density even during the zone transition period when the rotational speed is changed in a manufacturing device for an optical master disk of ZCLV system (zone contact linear velocity system). SOLUTION: The rotational speed of a motor 11 is changed according to a zone to generate a motor encode signal ME of frequency according to the rotational speed of the motor 11. A premaster clock signal PMC1 of frequency in synchronism with this motor encode signal ME is generated in a PLL circuit 16 and, simultaneously, the premaster clock signal PMC2 of frequency in synchronism with the motor encode signal ME and different from the premaster clock signal PMC1 is generated in a PLL circuit 17. Switching to the premaster clock signal PMC1 or PMC2 is made immediately when the zone is switched, which is selected as a master clock signal MS. Thus, the master clock signal MS is synchronized with the rotational speed of the motor 11 to transiently make the frequency thereof high immediately after the zone is switched. |
