Dynamic magnetic information storage or retrieval – General recording or reproducing – Signal switching
Reexamination Certificate
2001-02-16
2003-06-10
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Signal switching
C360S063000, C360S077020, C360S078040, C360S078050
Reexamination Certificate
active
06577464
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic recording device having a magnetic head which reads and writes magnetic information while moving relative to a magnetic recording medium, and more particularly, relates to an improved magnetic recording device having a first actuator for coarsely adjusting the movement of a magnetic head relative to a magnetic recording medium, and a second actuator for finely adjusting the movement of the magnetic head.
2. Description of the Related Art
Conventionally, a magnetic recording device with a configuration shown in
FIG. 5
is known as an information recording device for use in personal computers.
In a magnetic recording device M shown in
FIG. 5
, a plurality of disklike magnetic disks
100
, which are coated with a magnetic film, are rotatably housed in a box-shaped chassis
101
. Magnetic heads
102
are placed on the front or back sides of the magnetic disks
100
so as to move relative to the magnetic disks
100
. Each of the magnetic heads
102
is supported by a base
105
via a load beam
103
shaped like an elongated triangular plate and an arm
104
. The base
105
is movably supported in the chassis
101
. That is, in the configuration shown in
FIG. 5
, the magnetic head
102
is moved relative to the magnetic disk
100
in the radial direction by movement of the base
105
so as to read out magnetic information recorded on a desired position of the magnetic disk
100
or to write magnetic information on a desired position of the magnetic disk
100
.
Regarding the driving structure for the base
105
shown in
FIG. 5
, the base
105
is rotated on a rotating shaft
106
in parallel with the rotating shaft of the magnetic disk
100
, and the magnetic head
102
is thereby moved in the radial direction above (or below) the magnetic disk
100
. The base
105
may be driven in various ways, for example, by a driving structure using a voice coil motor or by a driving structure using a linear motor.
In the magnetic disk device M shown in
FIG. 5
, various signals, such as control signals for the magnetic heads
102
, signals of magnetic information read by the magnetic heads
102
, signals of magnetic information to be written on the magnetic disks
100
by the magnetic heads
102
, and selection signals for the magnetic heads
102
, must be exchanged between a main control device and the magnetic heads
102
.
For this reason, conventionally, a main control device
107
disposed in the chassis
101
and the base
105
are connected by a flexible printed circuit board
108
, and various wires are laid on the printed circuit board
108
so as to connect the main control device
107
and the magnetic heads
102
.
FIG. 6
schematically shows the state in which the printed circuit board
108
, connectors
109
of the main control device
107
, and the magnetic heads
102
are connected.
In this example, two magnetic disks
100
are stacked one above the other, and magnetic heads
102
are placed on the upper and lower sides of the magnetic disks
100
. Two connecting wires
111
are connected to each of the magnetic heads
102
and are routed onto the printed circuit board
108
. The connecting wires
111
are connected to terminals
115
disposed on one side of a control element
112
placed on the printed circuit board
108
. Terminals
116
on the other side of the control element
112
are connected to the connectors
109
of the main control device
107
via a plurality of connecting wires
113
.
The connecting wires
111
connected to the four magnetic heads
102
are connected in order from the top to the terminals
115
which are also arranged on one side of the control element
112
in order from the top in
FIG. 6
, and are laid out so as not to intersect on the printed circuit board
108
. The terminals
116
on the other side of the control element
112
are connected to the connector
109
of the main control device
107
via the connecting wires
113
which are laid in parallel so as not to intersect on the printed circuit board
108
. In the terminals
115
shown in
FIG. 6
, Vcc represents a power input terminal, R/W represents a read/write mode switching terminal for the magnetic head
102
, RD represents a read signal output terminal, HS0 and HS1 represent magnetic head selection terminals, WDI represents a write data input terminal, WUS represents a writing enable signal terminal, and GND represents a ground terminal.
With recent increases in recording density of magnetic disks, the width of tracks formed on the magnetic disks have been reduced year by year. Conventionally, the width of tracks (thin information writing areas formed on a magnetic disk in the circumferential direction) is set so that approximately forty thousand tracks can be formed per inch, for example, the track width has been reduced to approximately 0.5×10
−6
m. Therefore, if the track width is further reduced, it may be difficult for the magnetic head to precisely trace the tracks of such reduced width in the driving mechanism for the magnetic head utilizing rotation of the base
105
, the driving mechanism utilizing a voice coil motor, or the linear driving mechanism. For example, it is thought that stability of the control system cannot respond to further reduction in track width in the existing driving mechanism for the magnetic head because of structural limitations of a bearing system.
Accordingly, attempts have been made to precisely and finely adjust the position of the magnetic head by providing a second actuator, which allows finer movement, in addition to the conventional driving mechanism. While various elements have been proposed as the second actuator, a piezoelectric actuator has attracted great attention as a promising driving element.
While the piezoelectric actuator is characterized in being capable of finely adjusting the position of the magnetic head by controlling current application thereto, when wires of the piezoelectric actuator are incorporated in the wiring structure shown in FIG.
6
and the control element
112
, the number of wires is increased. This makes it difficult to lay the wires in parallel on the printed circuit board
108
so as not to intersect with one another.
While the voltage for controlling the magnetic head is usually approximately ±5 V or ±3.3 V, the control voltage for the piezoelectric actuator is approximately ±30V, which is high. Therefore, it is difficult to incorporate both a transistor for controlling the piezoelectric actuator and a transistor for controlling the magnetic head in the same control element
112
, because this increases the withstand voltage of the transistor for the magnetic head.
When the wires of the piezoelectric actuator are laid on the printed circuit board
108
in addition to the wires of the magnetic head, the number of wires on the printed circuit board
108
is increased, and flexural rigidity of the printed circuit board
108
is also increased. The increase in flexural rigidity of the printed circuit board
108
increases the resistance when the base
105
shown in
FIG. 5
rotates. As a result, when the position of the magnetic head
102
is finely adjusted corresponding to the fine tracks, the printed circuit board
108
having increased flexural rigidity hinders improvement of the tracking accuracy. Therefore, it is preferable that the number of wires on the printed circuit board
108
be as small as possible.
Although the problems of intersection of wires can be easily overcome by providing a jumper switch on the printed circuit board
108
, this makes assembly and adjustment of the printed circuit board
108
more troublesome and decreases assembly efficiency and reliability.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-described circumstances, and an object of the invention is to provide a structure for a magnetic recording device having a first actuator for coarsely adjusting the position of a magnetic head relative to a magnetic disk and
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Faber Alan T.
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