| 摘要 |
PROBLEM TO BE SOLVED: To enable the wobble recording of a header part and a groove part by using a circuit with a small number of counters with a small number of bits by a method wherein the grooves are wobbled for tracking with a certain period whose phase is approximately identical to the phase of the period with which the prepit rows of an address region are wobbled. SOLUTION: A wobble start counter 15a starts counting a channel clock by receiving a header part wobble start pulse and, when the counted value reaches a predetermined number, outputs a wobble start pulse by which a wobble 1 cycle counter 15b outputs counted values of one cycle units. In accordance with the counted values of one cycle units, a ROM 15c outputs a value corresponding to a sine wave every one cycle. The ROM 15c shifts a phase so as to have the leading end of the groove agree with the zero degree of the sine wave and starts recording at a starting position corresponding to the integer- times of a channel bit number in one period back from a finishing position. With this constitution, the wobble recording can be practiced by using a circuit with a small number of counters with a small number of bits. |
