| 摘要 |
PURPOSE:To realize an optical disk device which can surely move an optical beam, by using a specific output signal as an optical beam moving signal when information indicating the movement start of the optical beam cannot be read. CONSTITUTION:This optical disk is equipped with an AND circuit 11 which outputs an external mark 7 detecting signal (3) as an optical beam moving signal under a condition where a signal (1) is not outputted. When signal information a''-c'' indicating the movement start of an optical beam is read, an optical beam moving instruction (2) is outputted and an optical beam control circuit 6 outputs an optical beam movement starting signal (6) to an optical head (3) upon receiving a movement starting instruction (5) and moves the optical beam inward by one track. When the signal information a''-c'' cannot be read, the signal (1) and optical beam moving instruction (2) are not outputted. At this time, the output condition of the AND circuit 11 comes into existence and the external mark detecting signal (3) is outputted to an OR circuit 13. The signal (3) is further outputted from the OR circuit 13 to the optical beam controlling circuit 6 as an optical beam movement starting signal (6)' and the optical beam is moved inward by one track.
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