| 摘要 |
PROBLEM TO BE SOLVED: To realize a clock generation circuit for an optical disk device, which can be used for servo pattern detection also and is stably synchronized with a detected clock signal pattern by PLL at recording and is stably synchronized with reproduced data by PLL at reproducing, with one VCO(voltage controlled oscillator). SOLUTION: A first loop which detects the number of clocks between clock signal patterns through a route of a clock generator 12, a counter frequency division switch 6, and a switch 8 to perform PLL control, a second loop which performs PLL control with a clock signal pattern corrected by offset detected by trial recording through a route of the clock generator 12, an A/D converter 4, a phase difference detector 7 and the switch 8 at second and following recording, and a third loop which performs stable PLL control with phase information from a reproduced signal through a route of the clock generator 12, an A/D converter 13, a phase difference detector 14 and the switch 8 are switched, and the most suitable clock reproducing is performed in a synchronism pull-in process, at recording, at reproducing, at reproducing a no-signal part, etc. |
