Dynamic magnetic information storage or retrieval – Head mounting – For adjusting head position
Reexamination Certificate
1999-09-23
2002-03-26
Nguyen, Hoa T. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For adjusting head position
C360S244200
Reexamination Certificate
active
06362938
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to fine drive and positioning units and a memory apparatus and more particularly, to fine drive and positioning units and memory apparatus which can realize high speed, high resolution access while being suited for mass production.
The related art memory apparatuses includes, for example, a magnetic disc apparatus
700
as shown in FIG.
14
. This apparatus has a floating head mechanism
703
having a magnetic head
702
provided at a tip of a suspension arm
701
, a carriage
705
supported on a swing shaft
704
and mounted with the floating head mechanism
703
, and a voice coil motor
706
provided on an opposite side to the magnetic head
702
. The energization to the voice coil motor
706
causes the magnetic head
702
to swing about the swing shaft
704
. The magnetic head
702
floats over the rotating magnetic disc
707
.
Present memory apparatuses are rapidly increasing in recording density per unit area. The yearly increase of recording density so far has been approximately 25%. In recent years, however, it has reached as high as around 60%. Due to this, there is a demand for a head positioning mechanism that is capable of accessing at high speed and with high resolution. For such demand, technologies have been developed that include, for example, two voice coil motors for reducing the force of translation acted on a swing shaft and a two-staged actuator for providing rough and fine movements.
In the related art memory apparatus
700
shown in
FIG. 14
, however, there has been a problem in realizing high speed, high resolution access because the entire apparatus is vibrated due to a seek reaction force, thus increasing seek time. Meanwhile, it is a general practice to use a memory apparatus by switching over between seek and following control systems, in order to realize high speed seek and accurate track following. However, the switching between the control systems has posed a problem of time loss due to prolonged positioning time.
Meanwhile, in order to solve the above problem, a piggyback type magnetic disc has been proposed which is arranged with a voice coil motor between a suspension arm and a carriage (International Conference on Micromechatronics for Information and Precision Equipment, Tokyo, Jul. 20-23, 1997: MR-08 DEVELOPMENT OF INTEGRATED PIGGYBACK MILLI-ACTUATOR FOR HIGH DENSITY MAGNETIC RECORDING: Shinji KOGANEZAWA, etc., FUJITSU LIMITED).
The structure of this magnetic disc apparatus is shown in FIG.
15
. This magnetic disc apparatus
800
is structured by a positioning voice coil motor
803
arranged between a carriage
801
and a suspension arm
802
. The carriage
801
is mounted, at its one end, with a stator shaft
804
. Also, the carriage
801
is fixed with a magnet
805
. Furthermore, a coil
806
is provided opposite to this magnet
805
. The coil
806
is fixed on a head mounting block
807
. The head mounting block
807
is fixed on a cross shaped spring
808
of the suspension arm
802
. The cross shaped spring
808
is fabricated from an extremely thin steel sheet. Meanwhile, the cross shaped spring
808
at its center is spot-welded with the stator shaft
804
. At a tip of the suspension arm
802
, a gimbal
809
is formed. A slider (not shown) provided with a magnetic head is attached to an underside of the gimbal
809
. This magnetic disc apparatus
800
realizes seek time reduction due to short seek operation by the voice coil motor
803
.
However, there is a problem that this magnetic disc apparatus
800
requires an increased number of complicated and delicate parts and is thus not suited for mass production. Furthermore, because in the magnetic disc apparatus
800
the head mounting block
807
and the suspension arm
802
are made as movable parts, there is an increase in mass resulting in an increase of a seek reaction force. As a result, there has been a problem with limitation in seek time reduction.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a memory apparatus and fine positioning unit which is capable of realizing access at high speed and with high resolution and which is suited for mass production.
A first fine drive unit in accordance with the present invention in order to achieve the above mentioned object, comprises: a suspension arm for supporting a head portion formed on a slider; a rotation support portion for supporting one portion of the suspension arm and allowing the suspension arm to swing about the support portion; a support member arranged opposite to the suspension arm; a coupling portion provided on the support member and coupled to the suspension arm; a spring portion provided between the support member and the coupling portion; a fine head drive section having bi-directional cantilevers each having one fixed end and the other free end formed on the support member and piezoelectric members respectively provided on the cantilevers; and wherein the cantilevers are vibrated by applying a particular frequency of voltage to the piezoelectric members to cause the cantilevers to contact with the suspension arm thereby finely drive the head portion.
The application of a particular frequency of voltage to the piezoelectric members causes the piezoelectric members to expand and contract thereby vibrating the cantilevers. The suspension arm arranged oppositely to the support member continuously contacts with the cantilevers due to the vibration of the cantilevers. The suspension arm is given a divisional force acted sideways due to contact of the cantilevers. The suspension arm is coupled to the support member through the coupling portion. Because the coupling portion is held by the spring portion, the spring portion is elastically deformed by the sideways divisional force, causing the suspension arm to swing. The head section is moved by the suspension arm swing. The cantilevers are bi-directionally provided and accordingly the head section is capable of moving in opposite directions. As will be referred to later, a piggyback schemed memory apparatus can be structured by mounting the fine drive unit on a carriage driven by a voice coil motor.
A second fine drive unit in accordance with the invention, comprises: a support portion formed integrally with a coupling portion in an island form, a spring portion connected to the coupling portion and bi-directional cantilevers each having one fixed end and the other free end, wherein piezoelectric members are provided respectively for the cantilevers, and a rotation support portion being provided to support one portion of the suspension arm to allow the suspension arm to swing about the support portion; a head section formed on a slider to record data to a memory medium and reproduce data recorded in the memory medium; a suspension arm arranged opposite to the support member and supporting the head section; and wherein the cantilevers are vibrated by applying a particular frequency of voltage to the piezoelectric members to cause the cantilevers to contact with the suspension arm thereby finely drive the head portion.
This fine drive unit is integrally formed with the coupling portion, spring portion and cantilevers of the support member so that the suspension arm is provided on the coupling portion, thus enabling batch process and reducing the number of parts. This is suited for mass production. Also, if the piezoelectric members or rotation support portion are integrally formed, the production process will be further simplified.
In this fine drive unit, the application of a particular frequency of voltage to the piezoelectric members causes the cantilevers to vibrate similarly to the above, thereby swing the suspension arm that is arranged opposite to the support member. The suspension arm is coupled to the support member through the coupling portion, and the coupling portion is held by the spring portion. Accordingly, the spring portion is elastically deformed by the sideways divisional force due to the cantilever. This makes it possible to swing the suspension arm.
A first fi
Maeda Hidetaka
Suzuki Mizuaki
Suzuki Yoko
Tani Kazuo
Adams & Wilks
Nguyen Hoa T.
Seiko Instruments Inc.
Watko Julie Anne
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