Dynamic magnetic information storage or retrieval – Head mounting – For adjusting head position
Reexamination Certificate
2001-08-30
2004-03-16
Chen, Tianjie (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For adjusting head position
Reexamination Certificate
active
06707645
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head device that includes a reproducing device with a magneto-resistive (MR) head, and in which a piezoelectric element is provided on a supporting member for supporting the MR head, and in particular, to a magnetic head device that prevents the MR head from being broken.
2. Description of the Related Art
FIG. 5
is a plan view of a conventional hard disk drive. A magnetic disk
1
is rotated by a spindle motor
2
.
A load beam
4
is joined to an end portion
3
a
of a carriage having stiffness, and an end portion
4
a
of the load beam has a slider
5
provided with a flexure (not shown).
The load beam
4
is made of flat spring material. The load beam
4
has a base portion
4
b
that is fixed to the carriage
3
. The end portion
4
a
of the load beam
4
supports the slider
5
.
The slider
5
is provided with a reproducing device that uses magnetically resistive effects to detect a magnetic signal recorded on a magnetic disk
1
, and with a recording device that records a magnetic signal on the magnetic disk
1
. Airflow, caused by the rotation of the magnetic disk
1
, floats the slider
5
above the magnetic disk
1
. Recording and reproduction are performed in this floating state.
The carriage
3
has a base portion
3
b
provided with a voice coil motor
6
. The voice coil motor
6
drives the carriage
3
and the load beam
4
in the radial direction of the magnetic disk
1
, whereby a seek operation is performed to move the reproducing device and the recording device of the slider
5
onto an arbitrary recording track, and a tracking operation is performed to maintain the reproducing device and the recording device on the central line of the recording track.
As the recording density of the magnetic disk
1
is increased, the precision of the tracking operation must also be increased. Conventionally, the seek operation and the tracking operation are performed such that the voice coil motor
6
only drives the carriage
3
.
To increase the precision of the tracking operation, the servo band of a servo system including the voice coil motor
6
must be increased. However, the servo band is limited by a point of mechanical resonance between the carriage
3
and a bearing (not shown) that rotatably supports the carriage
3
. The mechanical resonant point of the carriage is determined by the size of the carriage
3
, and the size of the carriage
3
is determined by the standard-based diameter of the magnetic disk
1
. For example, when the magnetic disk
1
has a diameter of 3.5 inches, the point of resonance between the carriage
3
and the bearing is approximately 3.5 kHz.
When the point of resonance between the carriage
3
and the bearing is approximately 3.5 kHz, then the upper limit of the servo band of the servo system which allows the tracking operation by only driving the carriage
3
by the voice coil motor
6
is approximately 700 Hz.
Accordingly, a method has recently been proposed in which a tracking operation is performed by using a micromotion actuator provided on a load beam to move only an end portion of the load beam.
FIG. 6
is a perspective view of a load beam
11
provided with a piezoelectric element as a micromotion actuator. The load beam
11
is made of a flat-spring stainless-steel material and has a fixed base portion
11
a
held by a carriage and a moving portion
11
b
that can be horizontally moved with respect to the fixed base portion
11
a
. On both sides of a front end portion of the fixed base portion
11
a
, arm portions
11
c
extending in the longitudinal direction of the fixed base portion
11
a
are formed. The moving portion
11
b
is joined to the arm portions
11
c
by elastic supporting portions
11
d.
Piezoelectric elements
12
and
13
are provided on the moving portion
11
b
and the fixed base portion
11
a
across a gap portion
11
e
. The piezoelectric elements
12
and
13
are configured such that electrode layers
12
a
1
and
12
a
2
are respectively formed on the lower and upper surfaces of a piezoelectric element layer
12
b
, and electrode layers
13
a
1
and
13
a
2
are respectively formed on the lower and upper surfaces of a piezoelectric element layer
13
b.
The load beam
11
in
FIG. 6
is connected to a ground (not shown). The electrode layers
12
a
1
and
13
a
1
of the piezoelectric elements
12
and
13
are electrically connected to the load beam
11
, and are thereby connected to the ground. Each of the piezoelectric layers
12
b
and
13
b
of the piezoelectric elements
12
and
13
is polarized in the direction of the layer thickness. The piezoelectric elements
12
and
13
have reverse polarization directions. Therefore, when the same potential is applied to the electrode layers
12
a
2
and
13
a
2
, one piezoelectric element extends longitudinally, while the other piezoelectric element contracts longitudinally.
As a result, the elastic supporting portions
11
d
warp to change the posture of a slider
21
provided on an end portion of the moving portion
11
b
. In other words, by moving the slider
21
in a track-width direction, a tracking operation can be performed. By using a piezoelectric-element-mounted load beam to form a servo system, the servo band can be set to 2 kHz or greater.
The piezoelectric elements
12
and
13
are warped when a voltage is applied through conductor
14
to the electrode layers
12
a
1
,
12
a
2
,
13
a
1
, and
13
a
2
. Conversely, when the piezoelectric elements
12
and
13
are warped due to stress, a voltage is generated between the electrode layers
12
a
1
and
12
a
2
and a voltage is generated between the electrode layers
13
a
1
and
13
a
2
.
In particular, when touching some conductor, surge current may flow in the piezoelectric elements
12
and
13
because, in the process for ultrasonically cleaning or carrying the magnetic head device, large vibrations may act on the piezoelectric elements
12
and
13
. The surge current may reach a frequency of several hundred to several thousand megahertz and a magnitude of several amperes. This high frequency current causes an adjacent conductive pattern to generate an induced current. Also, a change in the voltage of the high frequency causes capacitive coupling with the conductive pattern, so that the current is transferred. In particular, when the magnetic head device is cleaned, current transfer occurs due to capacitive coupling caused by water having a dielectric constant several ten times that of air.
In particular, the reproducing device is often broken by the above current in the supersonic cleaning or carrying process since it has low durability against the above current.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a magnetic head device that reduces damage to a reproducing device and a recording device in a structure having a recording conductive pattern for transmitting a recording signal, and which comprises a control conductive pattern that supplies a control signal to a piezoelectric element connected thereto, and a reproducing conductive pattern that transmits a signal obtained by reproduction.
To this end, and according to the present invention, there is provided a magnetic head device including a slider provided with a reproducing device for using magnetoresistance to detect a magnetic signal recorded on a recording medium, and a recording device for recording a magnetic signal on the recording medium, a wiring member having a reproducing conductive pattern connected to the reproducing device and a recording conductive pattern connected to the recording device, and an elastic supporting member for supporting the slider and the wiring member. A piezoelectric element for changing the posture of the slider by warping the elastic supporting member is provided on the elastic supporting member, and the recording conductive pattern is formed between the reproducing conductive pattern and a control conductive pattern that is formed on the wiring member and
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Chen Tianjie
LandOfFree
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