Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
1998-11-25
2001-11-20
Young, W. R. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S077040
Reexamination Certificate
active
06320720
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a head-positioning system of a magnetic disk device, and particularly to that to be applied in a magnetic disk device provided with a fine-tracking actuator.
Conventionally, a combination of springs and carriages connected to a main actuator have been used for head-positioning of a magnetic disk device.
The controllable frequency band of head-positioning mechanism of this type is mainly defined by the oscillation frequency of a vibration mode of the head-positioning mechanism itself, and by suppressing the oscillation of the vibration mode making use of a notch filter, for example, a controllable frequency band of 600 to 700 Hz is attained.
Along with advancement of magnetic disks of high track density, however, further enlargement of the controllable frequency band is now earnestly required, and a two-stage actuator has been studied for replying to this requirement. In the two-stage actuator, a fine-tracking actuator is provided for each head besides the main actuator, which can move the head only a little but has a high-frequency vibration mode enabling to move the head in a wide frequency band.
However, the two-stage actuator has a problem that the fine-tracking actuator interferes with the main actuator and reaction of high-speed movement of the fine-tracking actuator may provoke the oscillation of the main actuator, and hence, the controllable frequency band of the fine-tracking actuator is also limited by the vibration mode of the main actuator.
For dealing with this problem, several proposals have been disclosed. In a Japanese patent application laid open as a Provisional Publication No. 11854/'93, a relative position of a tracking actuator to a linear motor of an optical head is detected, and the tracking actuator is feedback-controlled with a differential value of the relative position for suppressing auto-oscillation because of mutual interference.
In another Japanese patent application laid open as a Provisional Publication No. 174517/'93, a magnetic disk device having hybrid-servomechanism is disclosed, wherein tracking control is performed according to both a positional error signal detected by a reading head from a data recording surface and a positional error signal detected by a servo-head reading a servo-pattern recorded on a servo-pattern recording surface of the magnetic disk.
However, the first prior art of the Provisional Publication No. 11854/'93 needs a special detector for detecting relative position of the tracking actuator to the linear motor, which makes the mechanism complicated and a product cost thereof high because of increased numbers of parts, and the second prior art of the Provisional Publication No. 174517/'93 requires at least one servo-pattern recording surface, which degrades the data-formatting efficiency, especially of a slim-type magnetic disk device having but a few numbers of magnetic disks.
SUMMARY OF THE INVENTION
Therefore, a primary object of the present invention is to resolve the above problem with a simple configuration and to provide a head-positioning system which can control tracking movement of the magnetic head reliably and smoothly with a high speed, enlarging the controllable frequency band of the fine tracking actuator by suppressing interference between the fine tracking actuator and the main actuator.
In order to achieve the object, in a head-positioning system of the invention including a head-position control circuit and a head-positioning mechanism comprising a slider supporting spring for supporting a slider holding a read/write head, a carriage fixed to a carriage supporting shaft for rotating the slider supporting spring which is set rotatably to the carriage, a fine tracking actuator for driving the slider supporting spring in a rotational direction relative to the carriage, and a main actuator for rotating the carriage supporting shaft around a center axis of the carriage supporting shaft; the head-position control circuit comprises:
a phase compensating controller for obtaining deviation information of the read/write head relative to a designated position from the positional information detected by the read/write head, and generating a positioning correcting signal for feedback-controlling the fine tracking actuator to drive the slider supporting spring with a torque value to make the read/write head follow the designated position, according to the deviation information;
a vibration suppressing controller for forward-controlling the main actuator to maintain an angular position of the carriage to be fixed by controlling the main actuator to generate the same torque value with the torque value to be generated by the fine tracking actuator, referring to the positioning correcting signal;
an outside-disturbance suppressing controller for generating an outside-disturbance suppressing signal to compensate affect of outside disturbance impressed to the main actuator, by referring to an outside disturbance table wherein appropriate control values of the main actuator are registered for each cylinder number of a magnetic disk medium whereto the read/write head faces; and
a compensation signal generator for generating a compensation signal to be supplied to the main actuator by integrating outputs of the vibration suppressing controller and the outside-disturbance suppressing controller.
Therefore, a fine and high-speed tracking control of the read/write head can be realized making use of the fine tracking actuator, accurately and stably, by providing the vibration suppressing controller and the outside-disturbance suppressing controller.
REFERENCES:
patent: 3924268 (1975-12-01), McIntosh et al.
patent: 5177652 (1993-01-01), Yamaguchi et al.
patent: 5452275 (1995-09-01), Ogawa
patent: 6005742 (1999-12-01), Cunningham et al.
patent: 6034834 (2000-03-01), Yoshikawa et al.
patent: 6088187 (2000-07-01), Takaishi
patent: 5-11854 (1993-01-01), None
patent: 5-174517 (1993-07-01), None
Habermehl James L
McGuireWoods LLP
NEC Corporation
Young W. R.
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