Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Drum record
Reexamination Certificate
1998-11-04
2001-02-20
Miller, Brian E. (Department: 2754)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Drum record
Reexamination Certificate
active
06191915
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a suspension for supporting a head of a disc drive stored in an information processing apparatus such as a personal computer, portable computer, etc.
FIG. 11
shows a part of a hard disc drive (HDD)
1
. A carriage
2
of the disc drive
1
is turned around a shaft
2
a
by means of a motor
3
for positioning, such as a voice coil motor. The carriage
2
is composed of a coil portion
5
located near a magnet
4
of the motor
3
, arms (also referred to as actuator arms)
6
fixed to the coil portion
5
, suspensions
7
situated on the distal end side of the arms
6
, heads
8
attached individually to the respective distal end portions of the suspensions
7
, etc. Each head
8
can be moved to a desired track (recording surface) of a hard disc
9
by driving the carriage
2
by means of the motor
3
.
Each head
8
includes a slider
10
, which is situated in a position such that it can face the tracks of the disc
9
, a transducer (not shown) which is provided on the slider
10
, etc. When the slider
10
barely floats above the surface of the disc
9
as the disc
9
rotates at high speed, an air bearing is formed between the disc
9
and the slider
10
.
FIGS. 12
,
13
and
14
show an example of the conventional suspension
7
. The suspension
7
comprises a load beam
11
formed of a thin precision plate spring, a flexure
12
formed of a very thin plate spring fixed to the distal end portion of the load beam
11
, a base plate
13
fixed to the proximal portion of the beam
11
. The slider
10
is mounted on a tongue
12
a
that is formed on the flexure
12
. The stiffness of the flexure
12
is made so low that the attitude of the slider
10
floating low above the disc
9
can be flexibly changed.
A hemispherical support projection
15
protrudes from the distal end portion of the load beam
11
toward the flexure
12
. As shown in
FIG. 13
, the distal end of the support projection
15
is in contact with the tongue
12
a
of the flexure
12
. Therefore, the head
8
can make three-dimensional displacements, including pitching, rolling, etc., around the support projection
15
. The projection
15
, which is depressed inside, is also called a dimple in the art. The projection
15
may be provided on the flexure
12
instead of being formed on the load beam
11
.
With the progress of miniaturization of modern information processing apparatuses such as personal computers, the shock resistance properties of hard disc drives (HDDs) have become an important factor. In the case of an information processing apparatus that uses a small-sized hard disc (2.5-inch HDD), such as a so-called notebook computer, the shock-absorbing capability of its casing is not good enough. In the case of a desktop computer (using a 3.5-inch HDD), on the other hand, the HDD may possibly be subjected to a relatively heavy shock if it is handled wrongly in assembling operation.
When the aforementioned conventional suspension
7
was subjected to a shock exceeding its tolerance limit, the head
8
behaved unsteadily, and the head
8
and the disc
9
were damaged. The inventors hereof observed the behavior of the shocked head
8
by using a high-speed camera and the like, and found that the head
8
and the disc
9
were damaged in the following manner. When the suspension
7
was shocked, the distal end portion of the load beam
11
sprang up, as shown in FIG.
14
. Thereupon, the head
8
underwent pitching or rolling so that its corner portions (including a corner portion
8
a
) ran against the surface of the disc
9
. A phenomenon called dimple separation such that the flexure
12
and the support projection
15
separate from each other, in particular, promotes the aforesaid problem.
FIG. 15
shows the result of measurement of the respective displacements of the head and the support projection obtained when the conventional suspension was shocked. Test conditions include the shock duration time of 1 msec and acceleration of 460 G. As shown in
FIG. 15
, the mean value for dimple separation for the time interval from 0 to 5.5 msec is as large as 0.21 mm.
FIG. 16
shows the result of measurement of the change of the angle of inclination of the head in the pitching direction obtained when the conventional suspension was shocked. According to this test result, the range of inclination angle change of the head is as wide as 36.78°, and the head inclination reciprocates with relatively wide amplitudes in both the positive (+) and negative (−) directions.
Possibly, the occurrence of dimple separation and head inclination may be restrained by enhancing the stiffness of the flexure. If the stiffness of the flexure is increased, however, it is difficult to change the attitude of the slider flexibly when the slider floats low above the disc. Thus, stiffness of the flexure cannot be enhanced without a problem.
BRIEF SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a suspension for a disc drive that is capable of restraining excessive inclination of a head or occurrence of dimple separation when it is shocked, without enhancing the stiffness of a flexure, so that good shock resistance is enjoyed.
In order to achieve the above object, a suspension according to the present invention comprises: a load beam having a proximal portion and a distal end portion; a flexure attached to the load beam and including a moving part movable in the thickness direction thereof with respect to the distal end portion of the load beam, the moving part carrying a head thereon; and a limiter member attached. to the flexure and used to restrain the angle of inclination of the moving part. In the suspension according to the invention constructed in this manner, the moving part of the flexure can be restrained from excessively inclining by means of the limiter member when it is shocked. Accordingly, the head can be prevented from substantially changing its attitude and dimple separation can be restrained without enhancing the stiffness of the flexure.
According to the invention, the flexure may include a pair of outrigger portions, arranged individually on the opposite side portions thereof, left and right, and flexible in the thickness direction of the flexure, and a tongue portion, situated between the outrigger portions, having a front end portion continuous with the outrigger portions, and flexible in the thickness direction, the tongue portion carrying a head thereon. In this case, the tongue portion corresponds to the moving part of the flexure. In the suspension constructed in this manner, the outrigger portions and the tongue portion bend in the thickness direction. As the displacement of the tongue portion or the outrigger portions is restricted by the limiter member, excessive change of angle of the head or occurrence of dimple separation can be restrained.
In an aspect of the invention, the limiter member includes arms, detachedly facing the outrigger portions in the thickness direction thereof, and a front edge portion detachedly facing the rear end portion of the tongue portion in the thickness direction thereof. The limiter member constructed in this manner has a simple shape and configuration and is easy to manufacture. According to this arrangement, moreover, the limiter member can be easily combined with the flexure (e.g., by laser welding, adhesive bonding, etc.). When the head is inclined in the positive direction of the pitching angle, in the suspension provided with this limiter member, the rear end portion of the tongue portion engages the front edge portion of the limiter member, thereby restraining the head from further inclining. When the head is inclined in the negative direction of the pitching angle, the outrigger portions engage their corresponding arms, thereby restraining the head from further inclining.
In another aspect of the invention, the limiter member includes a first projection, detachedly facing one surface of the rear end portion of the tongue portion in the thickness direction t
Iriuchijima Osamu
Ishizaka Akinobu
Kashima Hideki
Ohkawara Osamu
Takagi Yasuji
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Miller Brian E.
NHK Spring Co. Ltd.
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