Mitsumi Electric Company Ltd.

Hidetsugu Touji

Yoshihide Majima

Toshiharu Shimizu

Toshimitsu Itoh

Hisakazu Hironaka

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. The plurality of tracks may be separated in a radial direction into a user data area and an alternate area which has an information identification sector for storing historic information in respect to preparation of the disk-shaped recording medium.

Disk-shaped recording medium and formatting method thereof wherein historic information including a storage capacity of the disk-shaped recording medium is recorded thereon

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.

Removable type magnetic recording/reproducing device

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.

Disk protection method for removable magnetic recording/reproducing

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.

Magnetic recording/reproducing device with an improved carriage location

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. The second and the fourth steps are carried out to ensure that the spindle motor chucks a disk hub of the large-capacity flexible disk. Each of the second and the fourth steps includes the steps of increasing the rotation speed of the spindle motor from the low rotation speed up to the high rotation speed by a predetermined abrupt acceleration; and rotating the spindle motor at a constant speed equal to the high rotation speed.

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Atsugi, Japan

Hidetsugu Touji