Head restraint device for disk drive

A head restraint that prevents head slapping within a hard disk drive. The disk drive includes a disk that is rotated by a spindle motor. The drive also has a magnetic recording head that is mounted to a flexure arm and magnetically coupled to the disk. The head restraint includes a finger that is moved from an unrestrained position to a restrained position to engage the flexure arm and prevent the head from moving in a direction essentially perpendicular to the disk.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a head restraint that prevents a magnetic 
recording head of a hard disk drive from striking the disk when the drive 
is subjected to a shock load. 
2. Description of Related Art 
Hard disk drives contain magnetic recording heads that are magnetically 
coupled to a rotating magnetic disk(s). Each recording head is typically 
mounted to a gimbal of a flexure arm. The head, gimbal and arm are 
commonly referred to as a head gimbal assembly (HGA). The flexure arms are 
attached to an actuator that has a voice coil. Data is typically stored 
along a plurality of concentric track across the radius of the disk. The 
voice coil cooperates with magnets to rotated the arm and move the 
recording heads across the surfaces of the disk so that the heads can 
access the various tracks of data. 
Each recording head has an air bearing surface that cooperates with a flow 
of air created by the rotating disk to create an air bearing. The air 
bearing separates the head from the disk to prevent mechanical wear of the 
two components. 
Hard disk drives are sometimes subjected to external shock loads that can 
cause the heads to strike or slap the disks. Such an event may damage the 
heads or the disks. For this reason some disk drives move the heads to a 
non-data portion of the disks when the drive is powered down. The actuator 
arm is then latched in place to prevent movement of the heads. 
Even when latched into position a shock load may still cause the heads to 
slap the disks. Although the heads are typically located in a non-data 
zone, head slapping may still create particles that contaminant the disk 
and corrupt the drive. It would therefore be desirable to provide a head 
restraint that prevents the recording heads from striking the disks when 
the disk drive has unloaded the heads. 
SUMMARY OF THE INVENTION 
The present invention is a head restraint that prevents head slapping 
within a hard disk drive. The disk drive includes a disk that is rotated 
by a spindle motor. The drive also has a magnetic recording head that is 
mounted to a flexure arm and magnetically coupled to the disk. The head 
restraint includes a finger that is moved from an unrestrained position to 
a restrained position to engage the flexure arm and prevent the head from 
moving in a direction essentially perpendicular to the disk.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to the drawings more particularly by reference numbers, FIG. 1 
shows a hard disk drive 10. The disk drive 10 includes a plurality of 
magnetic disks 12 that are rotated by a spindle motor 14. The spindle 
motor 14 is mounted to a base plate 16 of the drive 10. The disk drive 10 
also has a plurality of magnetic recording heads 18. The recording heads 
18 are coupled to electrical circuitry (not shown) which allows the heads 
to both write and read data from the magnetic disks 12. 
Each recording head 18 is mounted to a flexure arm 20 and magnetically 
coupled to an adjacent magnetic disk 12. The recording heads 18 and 
flexure arms 20 are constructed to create an air bearing between each head 
18 and adjacent disk 12 when the disks 12 are rotated by the motor 14. 
The flexure arms 20 are attached to an actuator arm 22. The actuator arm 22 
has a voice coil 24 that is coupled to a magnet assembly 26 to provide a 
voice coil motor. Actuation of the voice coil motor rotates the actuator 
arm 22 and moves the heads 18 across the surfaces of the disks 12. 
The disk drive 10 has a head restraint 28 that restrains the movement of 
the magnetic recording heads 18. The head restraint 28 has a plurality of 
fingers 30 that extend from a base portion 32. There is typically a finger 
30 for each flexure arm 20. The base portion 32 is pivotally connected to 
a post 34 of the base plate 16. The restraint 28 is preferably constructed 
from a low cost molded plastic material. The fingers 30 are preferably 
long enough to engage the recording heads 18 even when the heads 18 are 
located at the inner diameter of the disks 12. 
The head restraint 28 moves between a unrestrained position to a restrained 
position. The restraint 28 is biased into the restrained position by a 
torsion spring 36. One end of the torsion spring 36 is mounted to the base 
plate 16. The other end of the torsion spring 36 is attached to a mounting 
knob 38 of the head restraint 28. 
The rotating disks 12 create a flow of air within the disk drive. The air 
flow provides a corresponding pneumatic force on the fingers 30 that moves 
the head restraint 28 from the restrained position to the unrestrained 
position. When the disks 12 are no longer rotating the spring 36 moves the 
fingers 30 back to the restrained position so that the fingers 30 are 
located at the inner diameter of the disks 12. 
As shown in FIG. 2, each finger 30 has a slanted end 40. The ends of the 
fingers 30 engage the flexure arms 20 and prevent the heads 18 from moving 
in a direction essentially perpendicular to the disks 12. In one 
embodiment each finger end 40 is slanted to prevent a movement of the 
heads 18 away from the disks 12. It being understood that the heads create 
the most damage when initially moved away from the disk by a shock force 
and then snap back to strike the disk surface. The head restraint 28 of 
the present invention thus prevents a head snapping event from occurring. 
Additionally, the slanted finger ends 40 will compensate for tolerances in 
both the actuator arm assembly and the head restraint 28. Different 
tolerances may cause the flexure arms 20 to engage the restraint 28 along 
different points of the finger ends 40. 
In operation, when the disk drive is powered down the voice coil motor 
moves the heads 18 to a non-data portion at the inner diameter of the 
disks 12. The disks 12 no longer rotate, whereby the spring 36 moves the 
fingers 30 to the restrained position. The ends of the fingers 30 engage 
rails of the flexure arms 20 and prevent the heads 18 from slapping the 
disks 12. When the disk drive powers back up the disks 12 again rotate to 
create an air flow that moves the fingers 30 back to the unrestrained 
position. The voice coil can then move the heads 18 back to the data 
portions of the disks 12. 
While certain exemplary embodiments have been described and shown in the 
accompanying drawings, it is to be understood that such embodiments are 
merely illustrative of and not restrictive on the broad invention, and 
that this invention not be limited to the specific constructions and 
arrangements shown and described, since various other modifications may 
occur to those ordinarily skilled in the art.