| 摘要 |
PROBLEM TO BE SOLVED: To easily discriminate an optical disk whether it is the one contrived for increasing the recording capacity, or not. SOLUTION: A signal recorded on the optical disk is read out by rotating the optical disk at the desired speed and the position. The frame synchronizing signal of the obtained signal is detected. The detection period of the frame synchronizing signal is shortened by that the recording density of the high density optical disk becomes higher than that of the standard density optical disk. Based on the detection period of the frame synchronizing signal, the discrimination is allowed whether the optical disk is one contrived for increasing the recording capacity, or not. Also, the discrimination is available to execute based on the number of detecting times of the frame synchronizing signal for specified time. Further, the optical disk is similarly discriminated by utilizing also the synchronizing signal of the positional information formed with the use of wobble in a guiding groove.
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