| 摘要 |
PURPOSE:To attain a low cost by switching the tracking control system from the open loop to the closed loop state when the signal level of two tracking reference signals reaches a predetermined signal level or over. CONSTITUTION:The number of revolutions of a drive motor Md is increased gradually from a low state toward the predetermined number of revolutions. When the signal level of the two tracking reference signals in the reproducing signals reproduced from an information recording medium disk D by a recording and reproducing element RPE reach the level higher than the predetermined signal level respectively, moving contacts (c) of the changeover switches SW1, SW2 are switched from the position of a fixed contact (a) to the position of a fixed contact (b) thereby switching the tracking control system from the open loop to the closed loop. Moreover, the operating mode of the driving system of the disk P is designed so that the relative linear velocity between the disk D and the reproduced element RPE is controlled constant independently of the radial position on the disk D based on the result of comparison between the synchronizing signal reproduced from the disk D and the reference signal so as to attain excellent reproduction of an information signal from the equal linear velocity information recording disk D.
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