| 摘要 |
PURPOSE:To attain the stable address retrieval at high speed by providing a means moving an information detection point in a direction nearly orthogonal to a recording track at the speed in response to a relative position in the radial direction of a recording disk. CONSTITUTION:The width finfinity of a drive pulse takes a minimum value when an information detection point is placed at the innermost circumference of the recording disk 2 and the width finfinity is increased gradually as the information detection point is moved toward the outermost circumference. The duty ratio of the drive pulse of a slider motor 18 is changed depending on the width finfinity while the period of the vertical synchronizing signal is kept. A drive current is conducted to the motor 18 while the pulse exists, a torque is fed to the slider and while no pulse exists, a mechanical friction is exerted and the brake force is given to the slider and the slider torque is decided corresponding to the duty ratio. Thus, the moving speed is minimized when the information detection point is placed at the innermost circumference of the recording disk 2 and is increased gradually as the information detection point moves toward the outermost circumference.
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