Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Patent
1992-01-24
1998-12-01
Psitos, Aristotelis M.
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
360 7804, 360 7814, G11B 555
Patent
active
058447440
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a head positioning control apparatus of a disk drive and, more specifically, to a circuit for detecting the head position, driving the head in such direction as crossing the tracks on the disk and controlling the positioning operation of the head.
A disk drive to which the present invention will be applied is, for example, a magnetic disk drive which reads servo data recorded on a disk medium. The present invention relates to executed detection of head position and control of driving the head, responsive to servo data obtained by a readout operation.
Magnetic disk drives are increasingly being used as an external data storage apparatus. In one hand, request for large capacity is increased and on the other hand, request for small size, low price and high reliability is enhanced.
DESCRIPTION OF THE RELATED ART
The prior art will be explained with reference to FIG. 1, indicating a block diagram of a conventional head positioning control circuit.
In FIG. 1, the reference numeral 10 denotes a magnetic disk; 11, a servo head; 12, a voice coil motor; 13, a control current detecting circuit; 14, an object velocity generating circuit; 15, a velocity detecting circuit; 16, a velocity error detecting circuit; 17, a position error detecting circuit; 18, a power amplifier; 19, a servo signal detecting circuit; 20, a track crossing pulse generating circuit; 21, a main controller; 22, a selection circuit.
On a magnetic disk 10, servo data required for positioning of a servo head 11 is recorded, in addition to data being recorded. The servo head 11 is used for reading servo data from the magnetic disk 10. A voice coil motor 12 generates the force to move both servo head 11 and a data head crossing the tracks.
A servo signal detecting circuit 19 reads servo head recorded on the magnetic disk 10 with the servo head 11 and generates a position signal indicating the position of servo head 11.
A velocity detecting circuit 15 detects a moving velocity of the servo head 11 from the position signal generated by the servo signal generating circuit 19 and a motor drive current detected by a control current detecting circuit 13.
A velocity error detecting circuit 16 detects velocity error between the object velocity generated, during the coarse control, by an object velocity generating circuit 14 and the moving velocity of servo head 11 detected by the velocity detecting circuit 15, and outputs a voltage responsive to the velocity error.
A position error detecting circuit 17 detects position error from the position signal generated, during the fine control, by the servo signal detecting circuit 19 and a motor drive current detected by the control current detecting circuit 13, and outputs a voltage responsive to position error.
A selection circuit 22 outputs an input from the velocity error detecting circuit 16, during the coarse control (speed control), to a power amplifier 18 with a coarse/fine selection signal from a main controller 21, and also outputs an input from the position error detecting circuit 17, during the fine control (position control), to the power amplifier 18.
The power amplifier 18 converts a signal voltage outputted from the velocity error detecting circuit 16 or position error detecting circuit 17 into a current signal and then outputs such current signal to the voice coil motor 12.
A track crossing pulse generating circuit 20 generates a track crossing pulse which indicates that the servo head 11 has crossed the boundary between the one track and the other track, with the position signal generated by the servo signal detecting circuit 19.
The main controller 21 executes processings, such as setting of the number of tracks crossed until the head reaches the target track, initiation of velocity control, selection to position control from velocity control and detection of a number of the remaining tracks until the target track by counting the track crossing pulse, etc.
When a seek instruction is applied to the main controller 21 from a host apparatus, th
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Chiang, "Multirate State-Space Digital Controller for Sector Servo Systems" IEEE Proceedings of the 29th Conference on Decision and Control, pp. 1902-1907.
MEE et al. "vol. II; Computer Data Storage", 1988, pp. 53-84. McGraw Hill, Inc.
Patent Abstracts of Japan, vol. 12, 331 (P-755), Sep. 1988 & JP A-63 094 478 25 Apr. 1988 (abstract).
Hashimoto Shuichi
Negoro Toshio
Suzuki Nobuyuki
Fujitsu Limited
Habermehl James L
Psitos Aristotelis M.
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