| 摘要 |
PURPOSE: An optical disc type determination method is provided to definitely determine the type of a multi layer optical disc, like a DVD dual layer or a hybrid super audio CD, based on a detection time interval of a focus OK signal so that it enables a servo operation or a signal processing operation appropriate for the determined type. CONSTITUTION: The method comprises several steps. A microcomputer moves a focus lens down at an initial position, and gradually moves the focus lens up by driving a servo controller(S10). In a case that one zero crossing point is detected, the microcomputer starts counting time by driving a timer(S11). In a case that another zero crossing point is detected while a focus error signal is being monitored, the counted time is checked at every focus signal detection time interval(S12, S13). The checked detection time interval is compared with a reference. In a case that the checked detection time interval is larger than the reference, the type of the seated disc is determined as a hybrid super audio CD(S14, S15). In a case that the checked detection time interval is less than the reference, the type of the seated disc is determined as a DVD dual layer(S16). According to the determined type, a proper servo operation or digital processing operation is normally performed(S17).
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