| 摘要 |
PURPOSE:To obtain a non-eccentric type optical information medium having information recording grooves free of eccentricity by detecting the center of concentric or spiral tracks provided on a medium substrate and adjusting mutual positions of the medium substrate and an intermediate member to conform the center to the center of the center hole of the intermediate member. CONSTITUTION:When the center of the outer guide groove 27 of a disk 1 is not in conformity with the center of rotation of center top 29, if tracking of the outer guide groove 27 is made by an optical head 35, an error signal is generated. When this error signal is fed back to an actuator 31 through a coil 33, the actuator moves the disk 1 slightly in the direction of the arrow mark A. That is, the disk 1 slides on the center top 29 in the direction A. When the disk 1 is moved by driving of the actuator 31 until the center of the outer guide groove 27 coincides with the center of rotation of the center top 29, the optical head 35 makes tracking of the outer guide groove 27 regularly, and accordingly, driving of the actuator 31 is stopped. Thus, a non-eccentric type optical information medium having information recording grooves free from eccentricity can be obtained.
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