Dynamic magnetic information storage or retrieval – Head mounting – For shifting head between tracks
Reexamination Certificate
2000-02-09
2004-02-10
Hudspeth, David (Department: 2651)
Dynamic magnetic information storage or retrieval
Head mounting
For shifting head between tracks
Reexamination Certificate
active
06690549
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a storage device having a rotation driving unit for rotating a plurality of disk type of storage media each loaded on a coaxial basis on a center shaft, and a plurality of actuators for moving a head for picking up information from the storage media along the storage media in a radial direction of the storage media.
2. Description of the Related Art
As the storage device as mentioned above, there are known a magnetic disk unit and an optical disk unit. Here there will be described the magnetic disk unit by way of example.
Hitherto, according to the conventional magnetic disk unit, in many cases, a spindle motor (including a magnetic disk medium) is associated with an actuator on a one-to-one basis. Further, there is also known a magnetic disk unit in which a plurality of actuators are associated with one spindle motor to store or read a large volume of information into or from a medium, so that a processing speed of one magnetic disk unit is improved. However, according to such a type of magnetic disk unit as mentioned above, a plurality of actuators are disposed around the spindle motor. This arrangement needs a large occupation for the actuators and magnetic circuits and thus invites a larger device. Furthermore, there is considered an arrangement in which a plurality of actuators are rotatably moved on a coaxial basis (cf. for example, Japanese Patent Application Laid Open Gazette Sho. 58-23362, and Japanese Patent Application Laid Open Gazette Sho. 62-78783). However, according to such an arrangement, a plurality of actuators are simply superposed on a single rotary shaft, or there is provided a sub-base for integrating the actuators with the magnetic circuits. This is associated with a problem that it is difficult to provide a compactness of the device, and particularly very difficult to provide, for example, 3.5 inch disk factor (146 by 101.6 by 25.4 millimeters). According to the technologies proposed in the above-referenced documents, it is obliged to provide a large structure for the magnetic circuit. This involves an increment of the cost of the magnetic disk unit. Thus, it has to say that the technologies proposed in the above-referenced documents are for an especial device, but not for the general devices. Particularly, according to the magnetic disk unit in which actuators are laminated, there is a tendency that a frequency characteristic for enhancing a dynamic positioning performance of the actuators is degraded. Further, it often happens that a performance of moving and stopping a head for reading and writing information at a proper position is also degraded owing to a thermal distortion, a failure of accuracy in a size of a height direction, and the like.
Further, the above-mentioned magnetic disk unit having a plurality of actuators is associated with the following problems.
FIG. 1
is a schematic diagram of the conventional magnetic disk unit.
A magnetic disk
10
rotates on a center shaft
11
in a direction of an arrow A by a spindle motor (not illustrated).
The magnetic disk unit is provided with two actuators
20
. Each of the actuators
20
rotates on a rotary shaft
21
so that a magnetic head
30
provided on the top of the actuator
20
is moved in a radial direction of the magnetic disk
10
along the magnetic disk
10
. Each of the magnetic heads
30
records on the magnetic disk
10
information according to a signal transmitted from an associated signal recording/regenerating means
40
, or picks up information recorded on the magnetic disk
10
and transmits the same to the associated signal recording/regenerating means
40
.
The magnetic disk
10
stores therein information as to usual data to be read or written and in addition information as to a servo for a position control of the magnetic head
30
to the magnetic disk
10
. The magnetic head
30
picks up from the magnetic disk
10
a signal representative of information recorded on the magnetic disk
10
. Each of the signal recording/regenerating means
40
regenerates both the signals as to the data and the servo, which are picked up by the head
30
of the top of the associated actuator
20
, and transmits the same to a associated signal processing means
50
. Each of the signal processing means
50
processes the signals regenerated by the signal recording/regenerating means
40
, and instructs an associated position control means
60
to perform a position control for the associated actuator
20
in accordance with a processing result of the servo signal. Each of the position control means
60
controls the operation of the associated actuator
20
in accordance with the instruction from the associated signal processing means
50
so that the head
30
of the top of the associated actuator
20
moves to a desired position onto the magnetic disk
10
.
According to the magnetic disk unit shown in
FIG. 1
, each of the actuator
20
is provided with the magnetic heads
30
the number of which is the same as that of the recording surfaces of the magnetic disk
10
(when only one magnetic disk
10
is concerned, two surfaces of the front and the back, and when two magnetic disks
10
are concerned, four surfaces), wherein each of the magnetic heads
30
is placed against the associated recording surface. Thus, it is possible to simultaneously access the same recording surface of the magnetic disk
10
with total two magnetic heads
30
of the two actuator
20
.
FIG. 2
is a schematic diagram of an alternative conventional magnetic disk unit.
According to this magnetic disk unit, two actuators
20
are disposed in such a state that the two actuators
20
are laminated in a perpendicular direction with respect to the surface of the magnetic disk
10
. The two actuators
20
may rotate independently on the same rotary shaft
21
. In case of the magnetic disk unit, the total number of the magnetic heads
30
is the same as that of recording surfaces of the magnetic disk
10
(when two magnetic disks
10
are disposed on a laminating basis, four recording surfaces, and when three magnetic disks
10
are concerned, six surfaces), and a plurality of magnetic heads
30
(here two heads) are loaded on a plurality of actuators
20
(here two heads), respectively. Accordingly, it is possible to access a recording surface of the magnetic disk
10
with the associated one magnetic head
30
. On the other hand, according to this magnetic disk unit, since there are plurality of actuators, it is possible to enhance a degree of freedom in such a manner that while a magnetic disk
10
is accessed with one of the actuators, another actuator is moved for the purpose of the successive access, and thereby increasing an access speed.
In this manner, the scheme of providing a plurality of actuators makes it possible to increase an access speed. However, as shown in
FIGS. 1 and 2
, this scheme needs a plurality of systems of circuits for the signal processing and the servo control, so that a scale of the circuits is obliged to be enlarged and complicated. Thus, this scheme is associated with problems that it is disadvantageous in size, and the cost will be increased, too.
Those problems may be common to a storage device for the optical disk unit and the photomagnetic disk unit, but not restricted to the magnetic disk unit. Further, those problems may be common to a device for loading a read/write medium and also a device for loading a read-only medium.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a storage device having a plurality of actuators, which has a structure suitable for a miniaturization.
To achieve the above-mentioned objects, the present invention provides a first storage device comprising:
a rotation driving unit for rotating a disk type of storage medium loaded on a center shaft;
two actuators each having a head for picking up information from the storage medium, each of said two actuators rotating on a common rotary shaft and moving the associated head alo
Aikawa Koichi
Aruga Keiji
Asao Yasuyoshi
Jinzenji Akihide
Koizumi Yoshiaki
Fujitsu Limited
Greer Burns & Crain Ltd.
Hudspeth David
Slavitt Mitchell
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