| 摘要 |
PURPOSE:To detect a frame sink easily even during starting and perform speed control by controlling the rotation of a disk on the basis of a comparison output obtained by comparing the level of a peak holding output with a specific reference level. CONSTITUTION:An edge detector 6 is provided to generates an edge signal B by detecting the level transition of a reproduced EFM signal A, and this edge signal B is inputted to a triangular wave generator 7. A triangular wave is reset at the generation timing of the edge signal B, and at the same time, the generation of a new triangular wave starts. The positive peak of this triangular wave C is held by a peak holding ciruit 8, whose holding output (d) is compared with the reference level 4 by a comparator 5 to control the disk rotation on the basis of the comparison output. On the other hand, a dropout of: a reproduced RF (high frequency) signal is detected by a detector 9, and the triangular wave generator 7 is reset by the detection output of the detector 9. |
