Abstract: A schedule driving device drives a polyphase stepping motor via a drive circuit that supplies phase currents to the motor for moving the read/write head of a disk storage device. Phase data provided to the driving circuit is switched with the actual movement of a movable piece of the stepping motor. A position encoder coupled to the motor or a magnetic sensor generates a detection signal representing the position of the movable piece of the stepping motor. A programmed microcomputer then switches the phase data according to timing data stored in the microcomputer memory synchronized with the detection signal.

Abstract: A head position controller for a disc storage unit comprises a plurality of disc surfaces, and a plurality of read/write heads corresponding to the disc surfaces. Servo information is written into at least two disc surfaces. This controller comprises a selector for selecting one read/write head which can read the servo information written on a disc surface which is the closest to a read/write head to be selected as a head for reading out/writing recording information in accordance with specific bits in a head selection command, a detector for detecting an off-track amount in accordance with the readout servo information, and a circuit for correcting a position of read/write heads in accordance with the detected off-track amount.

Abstract: In a system for detecting a reference track on a disc for a disc storage unit, servo information for detecting an off-track amount of a position of a read/write head relative to the track is written on the disc surface. The servo information is formed by a repetition of simple patterns. A pattern of servo information for a reference track among those patterns is written at a frequency different from that for ordinary tracks. The write-in frequencies of the patterns for ordinary and reference tracks are discriminated from each other in accordance with the signals obtained by reading out the servo information written onto the tracks from the read/write head. When the write-in frequency for a reference track is discriminated, it is detected that the head is on the reference track. A reference track can be detected without having recourse to a particular sensor and a circuit attached thereto.

Abstract: A negative-phase braking control device for accurately stopping a plural-phase stepping motor in a very short time. The negative-phase braking control is performed by comparing the present position signal value representing the position of a rotor of the motor with the signal values which the present position signal value should take at a target position and at a predetermined position before the target position and controlling the rotation of the motor in the forward and reverse directions in accordance with the result of the comparison.

Abstract: Two reference information storage regions are arranged on each major surface of each disc with an angular spacing of 360.degree./4N (where N is the number of discs). The reference information storage regions for the respective discs are equiangularly displaced from each other, so that the reference information is read out from the angularly displaced reference information storage regions during each one rotation of the disc so as to detect a displacement of the head from its normal or proper position every time that the reference information is read out, and the displacement of the head is corrected in accordance with the detected displacement.

Abstract: A method and apparatus for driving a two-phase motor having two phase coils and a head of a disc recording unit which records information data and servo information on a rotatively driven disc in a manner designed to assure proper placement of the servo tracks and increase the speed of reading and writing information data. The head is driven to first radial locations on the disc by exciting phase coils in an unbalanced condition with two phase currents which have differing non-zero magnitudes, and servo information is written at these locations as the disc rotates.