Dynamic magnetic information storage or retrieval – Head mounting – For shifting head between tracks
Reexamination Certificate
1999-03-11
2003-08-26
Nguyen, Hoa T. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
For shifting head between tracks
Reexamination Certificate
active
06611404
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a disk apparatus, and more particularly to a disk apparatus for writing data to and reading data from a rotating floppy disk by movement of a head carriage.
2. Description of the Related Art
Conventionally, floppy disk apparatuses are widely used in personal computers as external memory devices. In recent years, in an effort to cope with the coming video age, floppy disk apparatuses have begun to be developed that greatly expand memory capacity from the current 1.44 MB to 200 MB or more. In order to expand memory capacity to such a large extent, it is necessary to increase the current 300 rpm rotation speed of the floppy disk by 10 times or more and at the same time increase the current track density of 135 tracks per inch (hereinafter tpi) by 10 times or more, to 2,000 to 3,000 tpi. In order to reliably write and read data under these high-speed, high-density conditions, a high degree of precision is required of the head carriage drive so as to position the magnetic heads with a high degree of precision.
FIG. 7
shows a head carriage drive mechanism
10
for a conventional high-density floppy disk device. The head carriage drive mechanism
10
has a head carriage
11
. The head carriage
11
has a head
12
and is moved and positioned longitudinally in the Y
1
-Y
2
direction along a radius of a rotating floppy disk
17
by a first voice coil motor
13
and a second voice coil motor
14
(hereinafter referred to collectively as first and second voice coil motors
13
,
14
) provided on either side of the head carriage
11
while being supported by guide rods
15
and
16
. The first voice coil motor
13
comprises a magnetic circuit structure
23
including a permanent magnet
20
and yokes
21
and
22
, and a drive coil
24
fitted to yoke
22
and fixedly mounted on the head carriage
11
. The second voice coil motor
14
comprises a magnetic circuit structure
33
including a permanent magnet
30
and yokes
31
and
32
, and a drive coil
34
fitted to yoke
32
and fixedly mounted on the head carriage
11
. The head carriage
11
moves longitudinally along the Y
1
-Y
2
axis in accordance with the drive current sent through the drive coils
24
and
34
. The wire of drive coil
24
and the wire of drive coil
34
have an identical diameter. Further, drive coil
24
and drive coil
34
have an identical number of turns so as to generate an identical propulsive force.
The head carriage drive mechanism
10
shown in
FIG. 7
has a signal wire
40
, an end of the signal wire
40
being attached to the head
12
and extending from the head
12
along an upper surface of the head carriage
11
in the horizontal X
2
direction at a position indicated as
41
in the diagram. The signal wire
40
has an extended section
40
a
having a length adequate to not restrict the movement of the head carriage
11
. The head carriage
11
is moved while moving the extended section
40
a
of the signal wire
40
(hereinafter extended signal wire section
40
a
).
At this point, it may be helpful to consider an X
2
-side load and an X
1
-side load arising when the above-mentioned head carriage
11
is moved longitudinally in the Y
1
-Y
2
direction. The X
2
-side load is greater than the X
1
-side load because the extended signal wire section
40
a
provided on the X
2
side must be dragged in addition to the head carriage
11
, thus creating a load imbalance between the X
2
side and the X
1
side of the head carriage.
Despite the existence of this load imbalance, however, the first and second voice coil motors
13
,
14
generate the same propulsive force. As a result, the precision with which the head carriage
11
is driven may deteriorate. In the case of a high-density disk with a track density in the range of 2,000 to 3,000 tpi, even a slight deterioration in the precision with which the head carriage
11
is driven can affect the accuracy and reliability with which data is written to or read from the disk.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a disk apparatus in which the problems described above are eliminated.
The above-described object of the present invention is achieved by a disk apparatus comprising:
a frame;
disk rotating means for supportably rotating a floppy disk;
a head for writing data to and reading data from a disk being rotated by said disk rotating means;
a head carriage for holding said head, said head carriage being movable in a direction of a radius of a disk supported by said disk rotating means; and
a first voice coil motor and a second voice coil motor for moving said head carriage provided on both sides of said head carriage, the first voice coil motor and second voice coil motor each respectively comprising:
a magnetic circuit structure mounted on said frame; and
drive coils mounted on said head carriage,
wherein said first voice coil motor generates a propulsive force on a first side of said head carriage corresponding to a load arising on said first side when said head carriage is moved, and said second voice coil motor generates a propulsive force on a second side of said head carriage corresponding to a load arising on said second side when said head carriage is moved.
The side on which the load is greater when the head carriage is being moved is driven with a propulsive force larger by just that greater load amount. Accordingly, each side of the head carriage is driven with a propulsive force corresponding in strength to the load on each side, that is, with a propulsive force that differs between the sides by an amount corresponding to the imbalance in load between the two sides.
As a result, it becomes possible to drive the head carriage with better precision and thus position the magnetic head with better precision than when the head carriage is driven with an identical propulsive force on each side. As a result of this more precise positioning, data can be accurately and reliably written to and read from even high-density disks having a track density in the range of 2,000 to 3,000 tpi.
Additionally, the above-described object of the present invention is achieved by the disk apparatus described above, wherein the first and said second voice coil motors are configured so that a number of turns in the drive coil of the first voice coil motor and a number of turns in the drive coil of the second voice coil motor differ so as to generate different respective propulsive forces corresponding to unequal loads on the two sides of the head carriage.
It is possible to alter the settings of the propulsive forces of the first and second voice coil motors, respectively, simply by changing the number of turns of the respective drive coils thereof, making it possible to flexibly accommodate changes in design.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 4763314 (1988-08-01), mcCaslin et al.
patent: 4906923 (1990-03-01), Aoyama
patent: 4908816 (1990-03-01), Champagne et al.
patent: 5111088 (1992-05-01), Fujino
patent: 5126905 (1992-06-01), Nomura et al.
patent: 5138605 (1992-08-01), Shtipelman et al.
patent: 5818666 (1998-10-01), Chaya
patent: 61877 (1986-06-01), None
patent: 61-101856 (1986-06-01), None
patent: 1-61877 (1989-04-01), None
patent: 4-19847 (1992-01-01), None
English Translation of Claim of Japanese Laid-Open Utility Model Application No. 62-165772 and English Translation of Abstract of Japanese Laid-Open Utility Model Application No. 4-103356.
Patent Abstracts of Japan, Publication No. 63140654 dated Jun. 13, 1988.
Patent Abstracts of Japan, Publication No. 63064562 dated Mar. 23, 1988.
Patent Abstracts of Japan, Publication No. 63124225 dated May 27, 1988.
Patent Abstracts of Japan, Publication No. 63124226 dated May 27, 1988.
Anderson Kill & Olick PC
Chen Tianjie
Lieberstein Eugene
Meller Michael N.
Nguyen Hoa T.
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