| 摘要 |
PURPOSE:To make a magnetic head follow a track, even if shift exists between the track and the magnetic head due to the eccentricity of a disc, by displacing the position of the magnetic head by an amount represented by the amount of eccentricity of the magnetic disc. CONSTITUTION:A track D recorded with a radius gamma0 in using a point A as a center is turned around a point B, and reproduction is performed with a magnetic head fixed to a point C apart from the point B by the distance gamma0. Then, a distance delta between the points A and B is the eccentricity and a distance between the point C and a point E represents a track shift (x). In this case, the track shift (x) is a value obtd. by subtracting a distance BE from the distance gamma0 and is expressed as the product of a distance delta and costheta. Since the angle theta is originated from the revolution of a magnetic disc rotating motor, the magnetic head can accurately follow the track by providing the displacement of deltacostheta to the head in synchronizing with the motor. |
