Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the head
Reexamination Certificate
2001-03-23
2004-02-24
Hudspeth, David (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the head
C360S078050, C360S075000, C360S078090
Reexamination Certificate
active
06697211
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a drive device for a read and/or write head that uses a micro-actuator, and more particularly, to a magnetic head drive device mounted at a tip of an arm in a drive unit for a magnetic disk or other recording media that eliminates vibration at the arm generated when the micro-actuator is driven, thus permitting precise positioning of the head relative to a desired track on a surface of the magnetic disk.
2. Description of Related Art
In recent years, as the density of recorded information increases, demand has arisen for an actuator arm that can be precisely positioned over extremely short ranges. The demand for precisely positionable dead drive devices is particularly great for head actuators mounted in optical focus correction and tilt control systems, printer devices, magnetic disk drives and the like.
Of these information processing devices, the disk drive units that drive magnetic and other rotating recording media are a key component of the multimedia devices that continue to gain added popularity. Multimedia devices, in order to process more video and audio data at faster speeds, continue to rely on development of higher-capacity equipment. Faster disk drive units, for example, have generally been obtained by increasing the per-disk recording density. However, increasing the recording density without changing the diameter of the disk necessitates increasing the number of tracks per inch, or TPI (as measured along the radius of the disk), that is, the width of the tracks must be narrowed. Additionally, increasing the recording density narrows the track pitch, which in turn requires a head actuator capable of precisely positioning the read/write head (hereinafter referred to as the head) with respect to the recording track.
As a device intended to improve the precision with which the head is positioned, a so-called dual actuator-type head drive device has recently been proposed, which combines a micro-actuator for precise movement of the load arm, slider or head with the conventional head actuator.
For example, the present applicant has previously proposed a micro-actuator for a dual actuator-type assembly employing the shear deflection characteristic of a piezoelectric element. See Japanese Laid-Open Patent Application No. 11-31368. Separately and in addition thereto, a number of piezoelectric and electrostatic head drive devices employing micro-actuators have been proposed.
In general, there are three main types of micro-actuators, depending on the object to be driven, namely head suspension drive, slider drive, and head element.
Here, the slider drive and head element types of micro-actuators require a high degree of precise dimensional machining and have high production costs, both reasons that make the use of the head suspension-drive type of micro-actuator desirable. For these reasons as well, the applicant's previous submission, Japanese Laid-Open Patent Application No. 11-31368, also had to do with a head suspension type drive mechanism.
It should be noted that the head suspension referenced here comprises a main arm and an elastic sub-arm that is attached to a tip of the main arm, with the head fixedly mounted to the free remaining end of the sub-arm. The head suspension drive type of head movement mechanism disposes a micro-actuator that undergoes a slight displacement between the main arm and the head suspension, so the head (which is at the tip of the head suspension) can be positioned with a high degree of precision.
FIGS. 1A
,
1
B and
FIGS. 2A
,
2
B are diagrams illustrating a head drive device employing a conventional suspension drive arrangement.
FIGS. 1A
,
1
B and
FIGS. 2A
,
2
B show an example in which a piezoelectric element is used for the micro-actuator, in particular the shear deflection of the piezoelectric element. The principle of shear deflection is illustrated in
FIG. 1A
, in which a piezoelectric element
31
is polarized in a direction perpendicular to a direction of a thickness of the piezoelectric element
31
(the direction of polarization indicated by the blank dotted arrow) and electrodes
22
A,
22
B are mounted on top and bottom surfaces, with the electrode
22
B grounded and a voltage V supplied to the electrode
22
A. In such an arrangement, the piezoelectric element
31
undergoes a shear deflection.
Accordingly, by supplying a voltage V to the electrode
22
A in a state in which the electrode
22
B is grounded, the side on which electrode
22
A of the shear-type piezoelectric element
31
is disposed deflects from an original state shown by dotted lines in
FIG. 1B
to a left side while the electrode
22
B side deflects to a right side. As a result, by fixing the electrode
22
B side in place, the electrode
22
A side deflects in a direction indicated by the dotted arrow in FIG.
1
A. Additionally, in this state, if instead the electrode
22
A side were to be grounded and a voltage V supplied to the electrode
22
B, the electrode
22
A side would deflect in a direction indicated by the solid arrow in FIG.
1
A.
A fuller description of this type of piezoelectric element used as a micro-actuator in a conventional head drive device will now be given, with reference to
FIGS. 2A and 2B
. A head drive device
58
comprises a fixing member
20
that acts as a base, a driving member
30
disposed atop the fixing member
20
, and a movable member
40
positioned atop the drive member
30
. The fixing member
20
corresponds to the main arm described above, the movable member
40
corresponds to the sub-arm described above, and the driving member
30
corresponds to the micro-actuator described above.
As shown in
FIGS. 2A and 2B
, an electrode
21
is disposed atop the fixing member
20
, and is connected to a voltage generating part not shown in the diagram by a lead pattern
22
. The driving member
30
comprises two piezoelectric elements
31
arranged in parallel. The directions of polarization of the two piezoelectric elements
31
that form the driving member
30
are as indicated by dotted-line arrows, that is, perpendicular to a direction of a thickness of the piezoelectric elements and exact opposites of each other. The movable member
40
stacked atop the driving member
30
is composed of an electrically conductive metal. The movable member
40
comprises a base portion
43
that rests directly on the two piezoelectric elements
31
and a movement expansion portion
44
(hereinafter extension
44
) that projects from the base portion
43
, with a first notch
41
cut into the base portion
43
so as to divide the base portion
43
into two. The first notch
41
lies in a direction parallel to the direction of polarization of the two piezoelectric elements
31
of the driving member
30
. Further, a pair of second notches
42
are cut into a boundary portion between the base portion
43
of the movable member
40
and the extension
44
at both sides of the driving member
40
, the second notches
42
being formed in a direction perpendicular to the direction in which the first notch
41
is formed. A hinge
45
is formed between a tip of the first notch
41
and tips of the second notches
42
.
FIG. 2B
shows the head drive device
58
and actuator
52
of
FIG. 2A
in an assembled state. The electrode
21
of the fixing member
20
is connected to a controller
18
via an amplifier
19
, in such a way that the movable member
40
and the controller
18
are grounded. Accordingly, when a drive signal of a predetermined polarity is output from the controller
18
, this signal is amplified by the amplifier
19
and a predetermined voltage is supplied across the thicknesses of the two piezoelectric elements
31
, causing the movable member
40
to shift in the direction of the dotted arrow.
As a result, the movable member
40
(head suspension) shown in
FIGS. 2A and 2B
is moved slightly by driving the piezoelectric elements
31
(the micro-actuator) at the tip of the fixing member
20
(the main arm), so the head fixedly mounted at
Arent Fox Kintner Plotkin & Kahn
Fujitsu Limited
Hudspeth David
Wong K.
LandOfFree
Magnetic head drive device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic head drive device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic head drive device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3331705