Abstract: In a large-capacity FD comprising a disk-shaped recording medium on which a plurality of tracks are arranged with concentric circles, each track is divided into a predetermined number of sectors having a length equal to one another. Each sector consists of a serve field and a data field. The servo field in each sector includes a sector number field in which a sector number and alternation contents of the magnetic disk medium are written and a track number field in which a track number is written. The sectors on each track may be assigned with serial sector numbers in a circumferential direction in order with skipping over any defective sector. The plurality of tracks may be separated in a radial direction into a plurality of zones each including at least one alternate track.

Abstract: In a motor drive for driving a motor having three-phase coils in both a high rotation speed mode making the motor at a high rotation speed and a low rotation speed mode making the motor at a low rotation speed which is extremely lower than the high rotation speed, the motor drive comprises a mode selection circuit for making a connection of the three-phase coils unipolar and bipolar connections on the high and the low rotation speed modes, respectively. A frequency generation pattern detects a rotation speed of the motor. On the basis of the rotation speed detected by the frequency generation pattern, a combination of a PLL circuit and a driving transistor drives the motor at the high and the low rotation speeds on the high and the low rotation speed modes, respectively.

Abstract: In a motor drive for driving a motor having three-phase coils in both a high rotation speed mode in which the motor rotates at a high rotation speed and a low rotation speed mode in which the motor rotates at a low rotation speed which is extremely lower than the high rotation speed, the motor drive includes a mode selection circuit for making a connection of the three-phase coils unipolar and bipolar connections on the high and the low rotation speed modes, respectively. A frequency generation pattern detects a rotation speed of the motor. On the basis of the rotation speed detected by the frequency generation pattern, a combination of a PLL circuit and a driving transistor drives the motor at the high and the low rotation speeds in the high and the low rotation speed modes, respectively.

Abstract: In a disk protection method for protecting a magnetic recording disk upon ejection thereof from a removable magnetic recording/reproducing device by an eject mechanism through operation of an eject button, data writing relative to the magnetic recording disk is inhibited in response to a data write inhibit signal which is generated immediately after the operation of the eject button and before the eject mechanism actually starts the ejection of the magnetic recording disk. The eject mechanism actually ejects the magnetic recording disk from the removable magnetic recording/reproducing device in a condition where the data writing is inhibited.

Abstract: A carriage location detector comprises a scale formed on a carriage and having a plurality of slits at a predetermined interval, a photointerrupter including at least one light emitting element and a plurality of light receiving elements arranged opposite to each other with the scale interposed therebetween. The light receiving elements are so that output signals thereof have a phase difference of 90.degree. from one another. A processing circuit is responsive to the output signals from the light emitting elements for carrying out processing, in an initial setting operation, so as to keep voltage waveforms of the output signals within a predetermined range.

Abstract: In a method of starting rotation of a magnetic disk medium of a large-capacity flexible disk by a spindle motor for use in a high-density type flexible disk drive for carrying out data recording and reproducing operation to and from the magnetic disk medium of the large-capacity flexible disk which requires to rotate at a high rotation speed on recording and reproducing, the method includes: a first step of rotating the spindle motor at a low rotation speed lower than the high rotation speed on rotation starting of the magnetic disk medium; a second step of rotating the spindle motor at the high rotation speed subsequently to rotating of the spindle motor at the low rotation speed; a third step of rotating the spindle motor at the low rotation speed subsequently to rotating of the spindle motor at the high rotation speed; and a fourth step of rotating the spindle motor at the high rotation speed subsequently to rotating of the spindle motor at the low rotation speed at the third step.