Method and apparatus for inspecting optical disc

Reflected light caused by reflection of a laser beam at a first layer of an optical disc is converted into a main signal. Reflected light caused by reflection of the laser beam at a second layer of the optical disc is converted into a sub signal. An address of a currently-accessed position in the fi...

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Bibliographische Detailangaben
1. Verfasser: Tokiwa, Kazunori
Format: Patent
Sprache:eng
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Beschreibung
Zusammenfassung:Reflected light caused by reflection of a laser beam at a first layer of an optical disc is converted into a main signal. Reflected light caused by reflection of the laser beam at a second layer of the optical disc is converted into a sub signal. An address of a currently-accessed position in the first layer is detected from the main signal. A reference address in the first layer corresponds to a boundary between a signal recorded area and a signal unrecorded area in the second layer. A specified address in the first layer corresponds to a position radially separated from the position at the reference address by an allowable range. A misalignment between tracks on the first and second layers is concluded to be within the allowable range in cases where the sub signal substantially takes a reference level when the detected address reaches the specified address.