| 摘要 |
<p>The rotation of a disc is so controlled as to have a constant angular velocity (CAV) in the inner region of the disc and as to have a constant linear reading velocity (CLV) for reading by a pickup in the outer region of the disc. The control mode is switched between the CAV control and the CLV control at the position where the angular reading velocity in accordance with the CAV control agree with the linear reading velocity in accordance with the CLV control. Control data for determining the switching position between the CAV control and the CLV control are set in a recorded information reproducing device. Making reference to frame synchronization signals, etc., which are generated in accordance with reading signals which are obtained from the disc in a reproducing operation, it is judged whether or not the scanning position of the pickup reaches the switching position determined by the control data. When it does, the control mode is switched from the CLV control to the CAV control. In order to allow the target values to reflect the variations in eccentricity and surface instability of the discs, the target data can be obtained by utilizing a training period. With this constitution, the maximum rotational speed of the disc is set as high as possible in accordance with the variations of the discs to switch the CAV control and the CLV control easily.</p> |
