| 摘要 |
The present invention has an object to stably reproduce wobble signals of all disks of CD-R/RW, DVD-R/RW and DVD-RAM by one wobble signal reproducing circuit. In the wobble signal reproducing circuit, an AGC (AUTOMATIC GAIN CONTROL) circuit for equating a push-pull circuit output of a wide range and an RF amplitude of an optical detector output of two systems obtained by push-pull, and an AGC circuit for making a wobble amplitude uniform are provided with a function to hold a gain or to change over a response time constant, and an address information recording region (PID region) at the time of reproduction, the AGC (AUTOMATIC GAIN CONTROL) is held or the response time constant is changed over.
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