WOBBLE SIGNAL DETECTING DEVICE, ESPECIALLY FOR OBTAINING A STABLE WOBBLE SIGNAL EVEN THOUGH A TRACKING PROCESS IS UNSTABLE

摘要

PURPOSE: A wobble signal detecting device is provided to detect a top level and a bottom level of a wobble signal, and to obtain a middle value of the wobble signal while comparing the middle value with the wobble signal, thereby obtaining a binarized wobble signal having a stable duty rate even though a tracking servo is unstable. CONSTITUTION: A top level detector and holder(702) detects and holds a top level of an analog wobble signal. A bottom level detector and holder(704) detects and holds a bottom level of the analog wobble signal. An average unit(706) averages an output of the top level detector and holder(702) and an output of the bottom level detector and holder(704). A comparator(610) compares the analog wobble signal with an output of the average unit(706), and outputs a binarized wobble signal with a waveform shape.