Abstract:
A system and method are disclosed for improving the vibration/ mechanical shock-resistance of a hard disk actuator arm. A guide block is located behind the actuator arm&#39;s angular range of motion, preventing over-flexure/vibration during operation, and/or the drive&#39;s actuator screw head diameter is increased to minimize arm vibration.

Description:
BACKGROUND INFORMATION  
       [0001]     The present invention relates to magnetic hard disk drives. More specifically, the present invention relates to a system for damage prevention by improving the shock resistance of a hard disk actuator arm.  
         [0002]     There are several types of computer data storage devices. One is a hard disk drive (HDD). The HDD utilizes one or more magnetic disks to store the data and one or more heads to read data from and write data to the disk(s). As advances have occurred in the art of hard drive and other computer technology, hard drives and their associated computer systems have become small enough to enable portability. Along with the portability of such systems, comes an increased risk of shock or vibration causing either impaired read/write ability or damage to the hard drive.  
         [0003]     If a hard drive experiences severe vibration or mechanical shock, the actuator arm, which positions the head over the magnetic disk, may impact the disk, potentially damaging either the head or disk or both. In addition, damage may occur to components such as the arm suspension and physical and electrical connections. Further, if a micro-actuator system is utilized for fine-tuning of head placement, damage could occur to the micro-actuator itself. In the art today, different methods are utilized to prevent such damage.  
         [0004]      FIG. 1  illustrates a typical method utilized to prevent damage caused by shock or vibration to a hard drive. A stationary ramp  102  is located near the outer edge of the disk  104 . When the head  106  is moved beyond the edge of the disk, it rides onto the ramp  102 , where it is ‘parked’ in a safe, restrained position. One problem with this design is that it is only effective during hard drive non-operation. It is unable to prevent damage during normal drive operation when the head  106  is reading data from and writing data to the disk  104 . Further, a ramp  102  may only be used with ‘diagonal arm orientation’ hard drives  108 , as shown in  FIG. 1   a.  Because of space limitations, a ramp  112  may not be utilized with ‘perpendicular arm orientation’ hard drives  110 , as shown in  FIG. 1   b.    
         [0005]      FIG. 2  provides an illustration of another method of preventing shock/vibration-associated damage, which involves the utilization of a stationary ‘comb’. As shown in  FIGS. 2   a  (top view) and  2   b  (side view), the comb  206  is affixed to the hard drive casing  212  in a location such that each of the disks  202  and each of the arms  204  has a position interposed between ‘teeth’  208  of the comb  206  throughout the arm&#39;s  204  range of motion (See  FIG. 3 , also).  
         [0006]      FIG. 3  provides another illustration of the ‘comb’ method of arm stabilization.  FIGS. 3   a  and  3   b  show the arms  304  at the opposite end of their range of motion  314 . One disadvantage of the ‘comb’ method is that there is a substantial portion (the load beam  316 ) of the arm  304  that is unconstrained by the comb  306 . This portion  316  of the arm is free to move toward and away from the disk  302  under vibration or mechanical shock in a ‘spring-like’ manner. Another disadvantage is that the comb  306  supports only the base plate portion  318  of the arm and not the suspension (load beam  316 ) of the head  320  (discussed below). Further, the distance from the support of the comb  306  to the head  320  is relatively large, allowing for substantial displacement of the head under shock/vibration. It is therefore desirable to have a system for improving the shock resistance of a hard drive actuator arm in addition to other advantages.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  illustrates the ‘ramp’ method for preventing damage caused by shock or vibration to a hard drive.  
         [0008]      FIG. 2  provides an illustration of another method of preventing shock/vibration-associated damage, which involves the utilization of a stationary ‘comb’.  
         [0009]      FIG. 3  provides another illustration of the ‘comb’ method of arm stabilization.  
         [0010]      FIG. 4  illustrates a single-head hard drive utilizing an actuator arm guide block under principles of the present invention.  
         [0011]      FIG. 5  illustrates increasing the diameter of the actuator screw under principles of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0012]     To improve shock resistance of the hard drive, in one embodiment of the present invention, a guide block is provided to support/restrain the actuator arm from behind (i.e., the side facing away from the surface of the disk).  FIG. 4  illustrates a single-head hard drive utilizing an actuator arm guide block under principles of the present invention.  FIG. 4   a  provides a perspective view of a hard drive with guide block, and  FIG. 4   b  provides a side view of the actuator arm and guide block under principles of the present invention. In one embodiment, an ‘arc’-shaped guide block  402  is coupled to the hard drive casing  404  behind the actuator arm  406  to prevent the arm  406  from flexing away from the disk  408  during shock or vibration. The arm  406  is thus not allowed to bend away (downward, in this illustration) from the disk  408 , preventing damage to the arm (over-flexure) and/or disk (by impact upon return swing). In one embodiment, the guide block  402  is shaped to follow the path of the head suspension (load beam)  410  through the arm&#39;s  406  angular range of motion.  
         [0013]     In one embodiment, the guide block  402  is made of a metal, such as stainless steel; in another embodiment, the guide block  402  is made of a polymer, such as polyethylene, polyester, or polyamide; and in another embodiment, the guide block  402  is ceramic.  
         [0014]     In one embodiment, the guide block  402  has two different surfaces (steps). The first step  412  supports the main portion of the arm  406 , and the second step  418  supports the load beam portion (suspension)  410 . This design allows the load beam  410 , which can articulate somewhat with respect to the main portion of the arm  406 , to be supported independently. In one embodiment, a portion of the guide block  402  near the center of the disk  408  serves as a load/unload station  420  to constrain the arm  406  during non-operation of the hard drive.  
         [0015]     In one embodiment of the present invention, an actuator screw is utilized that has ahead (crown) large enough to reduce arm vibration.  FIG. 5  illustrates increasing the diameter of the actuator screw  502  under principles of the present invention. Common in the art today is a screw head diameter of 5.3 millimeters (mm). In one embodiment, a screw with a larger-diameter head  502  provides axially-directed compression upon the arm over a greater area, thus reinforcing and stabilizing the arm  504  under that area. Further, it provides pressure farther away from the axis, giving a greater moment for resisting vibration/shock-induced flexure (torsion). In one embodiment, an actuator screw  502  with a head diameter of 8.4 millimeter (mm) is utilized with a 3.0 inch hard drive. In one embodiment, an 8.4 mm screw head  502  is utilized with a 3.5 inch hard drive. Preferably, in 3.5 inch hard drives, the head diameter of the screw is between 8.4 mm and 9.4 mm to achieve the vibration/shock resistance of the present invention. In another embodiment, a generally 8.4 mm head diameter screw  502  is utilized to provide the benefits of a large-headed screw  502 , yet satisfy space limitations of a 3.5 inch hard drive such as the Maxtor Nike 3.5 inch drive. This provides a screw head diameter  508  that is 44.9% the width  510  of the arm (at the midpoint of the screw and perpendicular to the length of the arm  504 ) for a hard drive such as the Maxtor Nike 3.5 inch platform, which has an arm width  510  of 18.7 mm. Preferably, in 3.5 inch hard drives, the ratio between head diameter and arm width is between 28.3% and 50.3% to achieve the vibration/shock resistance of the present invention.  
         [0016]     Although several embodiments are specifically illustrated and described herein, it will be appreciated that modifications and variations of the present invention are covered by the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.