Nec Corporation

Yoshihisa Okawa

Yoichi Murakami

Terumitsu Okamoto

Takao Ishikawa

A floppy disk drive comprises a read/write head and a pair of erase heads. The read/write head has a gap that extends across and beyond opposite edges of a track, while the gaps of the erase heads are aligned with each other and extend from the opposite edges of the track to create a pair of erased regions on opposite sides of the track. A wire circuit activates the read/write head in response to an output signal from a host system for recording signals along a sector of a track. An erase circuit activates the erase heads in response to the output of the host system for creating the erased regions along a length that corresponds to the sector. A fault detector is provided for detecting a potential developed by the erase heads to allow the write circuit to respond to the output of the host system when the potential is high and prevent the read/write head from responding to the output when the potential is low.

Disk drive with fault detector for erase heads

For controlling a relative position between a magnetic head (15) and a recording medium (10) having a control area (14) indicative of a tracking axis for the magnetic head, a position controlling unit comprises a producing arrangement (28) for producing a position signal, and a control arrangement (29) for controlling the relative position in response to the position signal in a predetermined direction which intersects the tracking axis. More particularly, the producing arrangement comprises a first producing, a second producing, and a processing arrangements (31, 32, 33). Responsive to the detection signal, the first producing arrangement produces a first signal. The processing arrangement processes the first signal into a second signal. Responsive to the first and the second signals, the second producing arrangement produces the position signal. Preferably, the control area has a main area (17) indicative of the tracking axis, and a supplementary area (18) preceding the main area. The magnetic head is for detecting the main and the supplementary areas to produce a main and a supplementary detection signal which collectively serves as the detection signal.

Exact position control of a relative position between a magnetic head

A magnetic disk apparatus has a circuit for detecting the recorded position of servo information, used for aligning a magnetic head, on a target track of a magnetic disk. The circuit discriminates the track's data area and the servo information area by determining an amplitude difference between detection signals equal or close to a discrimination frequency and the harmonic component of the discrimination frequency. If the amplitude difference exceeds a predetermined value, a servo area is discriminated. If the value is lower than the threshold, a data area is discriminated.

Magnetic disk apparatus having a circuit for detecting the position of

A servo protection circuit comprises a sync detector for generating a sync pulse in response to a sync code prerecorded in each sector of a magnetic disk to permit synchronism to be reestablished between the disk and the servo protect pulse at the beginning of each sector. In response to the sync pulse, a servo protect pulse is generated having a duration variable with the interval between successive ones of the sync pulse so that servo protection begins and ends with the beginning and ending points of each prerecorded servocontrol field. The servo protection circuit includes a delay circuit for introducing a shorter delay time of constant duration to the sync pulse to determine the trailing edge of the servo protect pulse and introducing a longer delay time of constant duration to the sync pulse to determine the leading edge of the servo protect pulse.

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Gunma, Japan

Yoshihisa Okawa