Actuator latch of hard disk drive

Details Actuator latch of hard disk drive Actuator latch of hard disk drive

2002-05-28

2004-06-15

Heinz, A. J. (Department: 2652)

Dynamic magnetic information storage or retrieval

Head mounting

For moving head into/out of transducing position

Reexamination Certificate

active

06751067

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Application No. 01-29254, filed May 26, 2001, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an actuator latch of a hard disk drive to lock a magnetic head in a parking region in a magnetic head transfer mechanism of the hard disk drive.
2. Description of the Related Art
In general, as illustrated in
FIG. 1
, a hard disk drive includes a hard disk
20
and a magnetic head transfer mechanism. The hard disk
20
, in which predetermined data is recorded, is rotatably installed on a base
10
. The transfer mechanism transfers a magnetic head
50
to a desired track on the hard disk
20
to record and reproduce data. Here, the hard disk
20
is divided into a recording region
22
to record data and a parking region
21
on which the magnetic head
50
arrives when the rotation of the hard disk
20
stops. The magnetic transfer mechanism includes an actuator
30
, a voice coil motor, and a latch. The actuator
30
, in which the magnetic head
50
is installed, rotates around a rotation axis
34
on the base
10
. The voice coil motor rotates the actuator
30
with an electromagnetic force. The latch locks the actuator
30
after the magnetic head
50
arrives on the parking region
21
.
The actuator
30
includes a suspension portion
31
, an arm
32
, and a bobbin
33
. The suspension portion
31
suspends the magnetic head
50
. The arm
32
is rotatably combined with the rotation axis
34
. A movable coil
35
of the voice coil motor is wound around the bobbin
35
. The voice coil motor includes the movable coil
35
and a magnet
41
, which is attached to a yoke
40
installed on the base
10
and generates a magnetic flux. The actuator
30
is placed between a pair of the yokes
40
, not shown in FIG.
1
. An electromagnetic force occurs due to the interaction between the magnetic flux generated by the magnet
41
and current flowing through the movable coil
35
. As a result, the actuator
30
rotates in a direction according to Fleming's left-hand law. The latch locks the actuator
30
so that the actuator
30
does not move after the magnetic head
50
arrives on the parking region
21
as described previously. The latch includes a magnetic member
43
, a damper
60
, and an iron separation element
61
. The magnetic member
43
is installed on the yoke
40
and magnetized by the magnet
41
. The damper
60
is inserted into a protrusion
36
at the end of the bobbin
33
of the actuator
30
. The iron separation element
61
is coupled to an end of the damper
60
. Thus, if the actuator
30
rotates and the magnetic head
50
installed at the suspension portion
31
enters the parking region
21
of the hard disk
20
, the iron separation element
61
coupled to one side of the bobbin
33
sticks to the magnetic member
43
as illustrated in FIG.
1
. The actuator
30
remains locked due to the magnetic combination of the iron separation element
61
and the magnetic member
43
until the electromagnetic force that rotates the actuator
30
operates again. The reason for locking the actuator
30
will be described below.
The suspension portion
31
to suspend the magnetic head
50
provides an elastic force biasing the magnetic head
50
toward the horizontal plane of the hard disk
20
. Thus, the magnetic head
50
, to which an external force is not applied, keeps sticking closely on the horizontal plane of the hard disk
20
. However, if the rotation of the hard disk
20
begins, air moves around the magnetic head
50
due to the rotation of the hard disk
20
. The movement of air generates a lift force that lifts the magnetic head
50
from the horizontal plane of the hard disk
20
. Thus, since the hard disk
20
is rotating when data is recorded on or read from the recording region
22
of the hard disk
20
, the magnetic head
50
glides a predetermined distance above the horizontal plane of the hard disk
20
. Thus, scratches due to the friction between the recording region
22
and the magnetic head
50
do not occur on the recording region
22
.
However, if the rotation of the hard disk
20
completely stops as when power is turned off, the lift force that lifts the magnetic head
50
disappears. Thus, the actuator
30
rotates so that the magnetic head
50
is positioned on the parking region
21
before the lift force disappears. As a result, the magnetic head
50
safely arrives in the parking region
21
, which is not related to recording and/or reproducing data, and thus does not have a negative effect on the recording region
22
although the lift force disappears as the rotation of the hard disk
20
stops.
However, if the magnetic head
50
is pushed toward the recording region
22
due to an impact after the magnetic head
50
safely arrives on the parking region
21
, the magnetic head
50
keeps touching the recording region
22
until the magnetic head
50
is lifted again when the hard disk
20
is re-driven. As a result, scratches may occur on the recording region
22
. Hence, in order to solve this problem, the actuator
30
is locked using the latch so that the actuator
30
does not rotate although impact may be inflicted.
However, in this conventional latch, the actuator
30
is locked by a magnetic force which couples the magnetic member
43
to the iron separation element
61
. Thus, the actuator
30
is unlocked if a force greater than the magnetic force of the magnetic member
43
is applied. Also, the actuator
30
is unlocked and begins moving when the electromagnetic force generated between the movable coil
35
and the magnet
41
exceeds the combination force due to the magnetic force between the iron separation element
61
and the magnetic member
43
to re-rotate the locked actuator
30
. And, if the magnetic combination force between the iron separation element
61
and the magnetic member
43
is too small, the actuator
30
is easily unlocked even by a small impact. If the magnetic combination force between the iron separation element
61
and the magnetic member
43
is too great, the actuator
30
may not be unlocked even if the maximum electromagnetic force occurs to rotate the actuator
30
. In the above-described structure, the actuator
30
springs out sharply due to inertia when the actuator
30
is unlocked by overcoming the magnetic combination force. Thus, the protrusion
36
may strongly crash against a stopper
42
opposite to the magnetic member
43
. If the actuator
30
crashes against the stopper
42
, head slap may occur due to the crash impact. Thus, to prevent the head slap, the application of current to the movable coil
35
is controlled so that the actuator
30
is unlocked and supplied with a damping force.
It is difficult to design a control system since the timing to unlock the actuator
30
and supply the damping force to the actuator
30
is accurately set. Also, due to repetitive locking and unlocking operations, the damper
60
is under continuous stress and it may be destroyed.
Japanese Utility Model Publication No. 2-76368 discloses an actuator which is locked by coupling a magnet of a voice coil motor to a magnetic member at a side of the actuator with a magnetic combination force. The actuator presents the danger of head slap.
Korea Patent Publication No. 99-61734 discloses an actuator which is unlocked by biasing a latch to lock the actuator in a locking direction using a spring and selectively drive the latch in a direction opposite to a spring force using an electromagnet. The locking may not be strongly maintained due to the deterioration of the elasticity of the spring if the actuator is used for a long time.
Japanese Patent Publication No. 9-22568 discloses a latch which is locked and unlocked by a complicated electromagnetic mechanism including a permanent magnet, a low magnetoresistance device, and a coil. There are problems in that the complicated electromagn

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