| 摘要 |
A method for restoring focusing of a laser beam on a track of an optical disc for reading or writing data from/to the track when the focusing of said beam onto said track has been lost, wherein two categories, A and B, of focus lost causes are defined, A being due to an external shock and B due to other reasons and wherein a focus re-capture is performed with the use of focus control information stored in a memory only for a category B focus lost.
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