Pawl latch for ramp loading hard disk drivers

Details Pawl latch for ramp loading hard disk drivers Pawl latch for ramp loading hard disk drivers

2002-01-23

2004-05-04

Klimowicz, William (Department: 2652)

Dynamic magnetic information storage or retrieval

Head mounting

For moving head into/out of transducing position

C360S256400, C360S265100

Reexamination Certificate

active

06731468

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject matter disclosed generally relates to the field of hard disk drives.
2. Background Information
Hard disk drives contain a plurality of transducers that are magnetically coupled to rotating magnetic disks. The transducers can write and read information onto the rotating disks by magnetizing and sensing the magnetic field of the disks, respectively. The transducers are integrated into heads that are part of a head gimbal assembly (HGA). The HGAs are typically attached to an actuator arm that is pivotally mounted to a base plate of the drive.
Information is typically stored within a plurality of data sectors. The data sectors are located within annular tracks of the disks. The actuator arm has a voice coil that is coupled to a magnet assembly mounted to the base plate. The voice coil and magnet assembly together create a voice coil motor. The voice coil motor can be energized to pivot the actuator arm and move the transducers to different annular tracks of the disks.
Hard disk drives are typically assembled into computer systems such as a portable computer. Movement of the portable computer may induce a rotational acceleration of the disk drive. The rotational acceleration of the disk drive may cause the actuator arm to move about the drive and damage disk drive components. There have been developed a number of latches that secure the actuator arm and prevent undesirable arm movement. The latch is typically engaged when the heads are moved away and unloaded from the disks.
FIG. 1
shows a magnetic latch
1
that can secure an actuator arm
2
. The magnetic latch
1
is adjacent to a magnet assembly
3
that is coupled to a voice coil
4
of the arm
2
. The actuator arm
2
includes a steel pin
5
that is magnetically attracted to the latch
1
. The attractive magnetic force between the pin
5
and latch
1
maintains the position of the actuator arm
2
. The actuator arm
2
can only be separated from the latch
1
by providing enough current to the voice coil
4
to create a torque sufficient to overcome the magnetic force. This requires additional power for the hard disk drive, a criteria that is undesirable when used in a portable computer. Additionally, the use of a magnetic latch
1
may require complex actuator speed control that increases the software processing overhead of the drive.
FIGS. 2-4
show an inertia latch
10
that can secure an actuator arm
11
when the disk drive has clockwise rotational acceleration. The inertia latch
10
is normally biased in an open position away from the actuator arm
11
. When the disk drive is not writing or accessing information the actuator arm
11
is rotated to park the heads
12
on a ramp
13
. The arm
11
also engages a crash stop
14
. When the disk drive has a clockwise rotational acceleration the actuator arm
11
moves in a counterclockwise direction. The latch
10
also moves in a counterclockwise direction until a latch hook
15
extends into a notch
16
of the actuator arm
11
as shown in
FIG. 3
to secure the arm
11
.
As shown in
FIG. 4
, the latch
10
will move back to the open position when the disk drive is no longer rotationally accelerating. If the hard disk drive has a counterclockwise rotational acceleration, the actuator arm
11
will swing past the latch
10
in a clockwise direction and possibly land on the disks (not shown). This type of latch
10
will not secure the actuator arm
11
for counterclockwise rotational acceleration.
FIGS. 5-7
show a dual lever latch
20
which has a large latch arm
21
that can move a small latch arm
22
into an actuator arm
23
. The small latch arm
22
will engage the actuator arm
23
whether the disk drive has clockwise or counterclockwise rotational acceleration. When the disk drive is rotating in a clockwise direction the large latch arm
21
moves in a counterclockwise direction and a first latch pin
24
pulls the small latch arm
22
into the actuator arm
23
as shown in FIG.
6
. When the disk drive is rotating in a counterclockwise direction the large latch arm
21
moves in a clockwise direction and a second latch pin
25
pushes the small latch arm
22
into the actuator arm
23
as shown in FIG.
7
. The latch
20
will secure the arm
23
regardless of the rotational acceleration direction. This design requires multiple latch components that increases the complexity and cost of mass producing the disk drive.
FIG. 8
shows an impact rebound single lever bi-directional latch
30
. The latch
30
has a catch
31
that can engage a corresponding hook portion
32
that extends from an actuator arm
33
. When engaged, the hook
32
and catch
31
secure the actuator arm
33
when the disk drive is subjected to a rotational acceleration. The latch
30
includes a tab
34
that is coupled to a magnet (not shown). The tab
34
is attracted to the magnet to pull the latch
30
away from the hook
32
to detach the actuator arm
33
.
When the disk drive undergoes a clockwise rotational acceleration the actuator arm
31
and latch
30
will move in a counterclockwise manner. The actuator arm
36
may strike the latch
30
before the hook
32
and catch
31
have engaged. This premature contact may cause the latch to rebound and rotate back in the clockwise direction away from the actuator arm
33
. The disk chive includes a crash stop
35
which limits the movement of the latch
30
in the clockwise direction so that the hook
32
will still slide into the catch
31
. Having separate latch and stop parts increases the complexity and cost of mass producing the drives. It would be desirable to minimize the number of parts in the latch assembly.
BRIEF SUMMARY OF THE INVENTION
A latch for an actuator arm of a hard disk drive. The latch includes a catch portion, a pusher portion, and a crash stop portion that is located between the catch and pusher portions.


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