Patent Publication Number: US-7903369-B1

Title: Method of fabricating disk drives using a common disk drive base with an attached weight plate, and a disk drive including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. patent application Ser. No. 10/922,722, filed Aug. 19, 2004, which is incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to disk drives, and in particular to a method of fabricating disk drives using a common disk drive base with an attached weight plate, and a disk drive including the same. 
     2. Description of the Prior Art 
     The typical hard disk drive includes a head disk assembly (HDA) and a printed circuit board assembly (PCBA) attached to a disk drive base of the HDA. The head disk assembly includes the disk drive base, a cover, at least one magnetic disk, a spindle motor for rotating the disk, and a head stack assembly (HSA) that includes a transducer head supported by a slider for reading and writing data from and to the disk. 
     In certain applications, such as for use in consumer set top audio video applications, it is critical that the disk drive generated self-induced vibration is kept below minimum specified levels. Such vibration coupled with a poor chassis design that the disk drive is intended to be installed may result in vibrations that generate acoustic noise. Acoustic noise is a major source of distraction in such applications. In this regard, for such applications there are typically strict specifications for both disk drive vibration and overall vibration induced acoustic noise. Other applications, such as for desktop personal computers, may have much lower vibration specifications, even though such disk drives may otherwise meet desired memory capacity and speed performance requirements. 
     There is a need in the art for an improved method of manufacturing disk drives and improved disk drives in comparison to the prior art. 
     SUMMARY OF THE INVENTION 
     According to an aspect of the present invention, there is provided a method of fabricating disk drives. The method includes providing disk drives based upon a first disk drive configuration. The first disk drive configuration includes an operable disk drive including a disk drive base with an exterior bottom side, and a first weight plate attached to the exterior bottom side of the disk drive base. The method further includes providing disk drives based upon a second disk drive configuration. The second disk drive configuration includes the operable disk drive, and a second weight plate attached to the exterior bottom side of the disk drive base. The second weight plate has a mass different than a mass of the first weight plate. The first disk drives may be provided to a first customer, and the second disk drives may be provided to a second customer. In another arrangement, the first disk drives and the second disk drives are provided to a same customer. 
     According to another aspect of the present invention, there is provided another method of fabricating disk drives. The method includes providing disk drives based upon a first disk drive configuration. The first disk drive configuration includes an operable disk drive including a disk drive base with an exterior bottom side, and a weight plate attached to the exterior bottom side of the disk drive base. The method further includes providing disk drives based upon a second disk drive configuration. The second disk drive configuration includes the operable disk drive. The disk drive base is exposed without any weight plate attached to the exterior bottom side. The first disk drives may be provided to a first customer, the second disk drives may be provided to a second customer. In another arrangement, the first disk drives and the second disk drives are provided to a same customer. 
     According to another aspect of the present invention, there is provided a disk drive. The disk drive includes a disk drive base. The disk drive base includes an exterior bottom side, a bottom peripheral edge disposed about the exterior bottom side, and an exterior facing cavity formed in the disk drive base defined by the exterior bottom side. The bottom peripheral edge defines a disk drive form factor. The disk drive further includes a weight plate attached to the disk drive base within the exterior facing cavity. The weight plate includes an outer surface and an opposing inner surface. The inner surface is disposed towards the exterior bottom side. The outer surface is substantially aligned with the disk drive form factor. 
     According to various embodiments, the cavity defines a cavity cross sectional area aligned with the bottom peripheral edge, and the weight plate extends substantially across an entirety of the cavity cross sectional area. The inner surface may be cooperatively formed with the exterior bottom side. The exterior bottom side may include a structural honeycomb contour. The inner surface of the weight plate may be generally flat. The weight plate may be formed of a metal material, such as a steel material. The weight plate may be attached to the disk drive base such as through the use of fasteners. The weight plate may also be adhesively attached or press-fit attached. 
     According to yet another aspect of the present invention, there is provided a disk drive. The disk drive includes a disk drive base. The disk drive base includes an exterior bottom side, a bottom peripheral edge disposed about the exterior bottom side, and an exterior facing cavity formed in the disk drive base defined by the exterior bottom side. The bottom peripheral edge defines a disk drive form factor. The cavity defines a cavity cross sectional area aligned with the bottom peripheral edge, and the weight plate extends substantially across an entirety of the cavity cross sectional area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a disk drive including a disk drive base and a weight plate of an aspect of the present invention; 
         FIG. 2  is an enlarged perspective view of the disk drive base of  FIG. 1  after having been flipped as shown with a printed circuit board assembly and the weight plate exploded from the disk drive base; 
         FIG. 3  is the disk drive base, the printed circuit board assembly and the weight plate of  FIG. 2  as assembled; 
         FIG. 4  is a cross sectional side view of the disk drive base as seen along axis  4 - 4  of  FIG. 2 ; 
         FIG. 5  is a cross sectional side view of the disk drive as seen along axis  5 - 5  of  FIG. 3 ; 
         FIG. 6  is a bottom plan view of the disk drive base; 
         FIG. 7  is a plan view of an inner surface of the weight plate; 
         FIG. 8  is a plan view of an outer surface of the weight plate; 
         FIG. 9  is a plan view of an inner surface of a weight plate according to another embodiment; 
         FIG. 10  is a plan view of an outer surface of the weight plate of  FIG. 9 ; and 
         FIG. 11  is a perspective view of the weight plate according to another embodiment with a honeycomb contoured weight plate inner surface; 
         FIG. 12  is a perspective view of a disk drive base according to another embodiment with a generally flat exterior bottom side; 
         FIG. 13  (PRIOR ART) is a exploded perspective view similar to that of  FIG. 2 , however, with a prior art disk drive including an electromagnetic shield; and 
         FIG. 14  (PRIOR ART) is a cross sectional side view of the disk drive base as seen along axis  14 - 14  of  FIG. 13  as shown with the electromagnetic shield. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention only, and not for purposes of limiting the same,  FIGS. 1-12  illustrate a disk drive including weight plates in accordance with aspects of the present invention (with  FIGS. 13-14  depicting a prior art device). 
     Referring now to  FIG. 1  there is depicted an exploded perspective view of a disk drive  10  constructed in accordance with an aspect of the present invention. In the embodiment shown, the disk drive  10  includes a head disk assembly (HDA)  12  and a printed circuit board assembly (PCBA)  14 . The head disk assembly  12  includes a housing which may include a disk drive base  16  and a cover  18  that collectively house magnetic disks  20 ,  22 . Each magnetic disk  20 ,  22  contains a plurality of tracks for storing data. 
     The head disk assembly  12  further includes a spindle motor  24  for rotating the magnetic disks  20 ,  22  about an axis of rotation  26 . The head disk assembly  12  further includes a head stack assembly  28  that rotates between limited positions about a pivot axis  30 . The head stack assembly  28  includes a plurality of actuator arms, the lowermost one is denoted as  32 . A plurality of air bearing sliders, the lowermost one being denoted  34 , are distally supported by the actuator arms  32  respectively adjacent the disks  20 ,  22 . Each air bearing slider  34  includes a transducer head for reading and writing data from and to the disks  20 ,  22 . 
     According to another aspect of the present invention, there is provided the disk drive  10 . The disk drive  10  includes a disk drive base  16 . Referring now to  FIG. 2  there is depicted an enlarged perspective view of the disk drive base  16  of  FIG. 1  after having been flipped as shown with the printed circuit board assembly  14  and a weight plate  36  exploded from the disk drive base  16 .  FIG. 3  depicts the disk drive base  16 , the printed circuit board assembly  14  and the weight plate  36  of  FIG. 2  as assembled.  FIG. 4  depicts a cross sectional side view of the disk drive base  16  as seen along axis  4 - 4  of  FIG. 2 , and  FIG. 5  depicts a cross sectional side view of the disk drive  10  as seen along axis  5 - 5  of  FIG. 3 .  FIG. 6  depicts a bottom plan view of the disk drive base  16 . The disk drive base  16  includes an exterior bottom side  38 , a bottom peripheral edge  40  disposed about the exterior bottom side  38 , and an exterior facing cavity  42  formed in the disk drive base  16  defined by the exterior bottom side  38 . The disk drive  10  further includes the weight plate  36  attached to the disk drive base  16  within the exterior facing cavity  42 . The weight plate includes an outer surface  48  and an opposing inner surface  50  (as respectively shown in the plan views of the weight plate  36  of  FIGS. 7 and 8 ). The inner surface  50  is disposed towards the exterior bottom side  38 . The outer surface  48  is substantially aligned with the bottom peripheral edge  40 . 
     In further detail, the disk drive base  16  includes an exterior top side  44  opposite the exterior bottom side  38 . In this regard, the exterior top side  44  is disposed facing the cover  18 . The disk drive base  16  further includes a plurality of lateral sides  46   a - d  disposed lateral to the exterior bottom and top sides  38 ,  44 . The bottom peripheral edge  40  is disposed adjacent the lateral sides  46   a - d  proximate the exterior bottom side  38 . 
     As mentioned above the exterior facing cavity  42  is formed in the disk drive base  16  and is defined by the exterior bottom side  38 . In the embodiment shown, the exterior facing cavity  42  extends about halfway across the exterior bottom side  38  on that portion of the exterior bottom side  38  adjacent the lateral side  46   b . The printed circuit board assembly  14  is disposed adjacent the remaining portion of the exterior bottom side  38 . 
     As mentioned above, the weight plate  36  is attached to the disk drive base  16  within the exterior facing cavity  42 . In this regard, the weight plate  36  may be attached to the disk drive base  16  through the use of fasteners, such as screws  66  as shown in  FIG. 1 , and/or an adhesive for examples. It is contemplated that use of adhesives is particularly cost effective. While adhesives are generally disfavored in the context of disk drives, it is recognized that this application is external to the internal mechanisms of the disk drive  10  and therefore does not introduce contamination problems. Other methods of attachment may be chosen from those which are well known to one of ordinary skill in the art. As mentioned above, the weight plate  36  is attached to the disk drive base  16  within the exterior facing cavity  42  and substantially aligned with the bottom peripheral edge  40 . 
     The bottom peripheral edge  40  may define a cavity cross sectional area aligned with the bottom peripheral edge  40 . The weight plate  36  may extend substantially across an entirety of the cavity cross sectional area such as shown for example. As used herein the term substantially across refers to being at least ninety percent covered. Such coverage is contemplated to facilitate occupation of a substantial volume within the cavity  42  for modifying the overall mass of the disk drive  10  while maintaining the disk drive form factor. 
     The exterior bottom side  38  may include a spindle motor portion  52 . In this regard, the spindle motor  24  is disposed adjacent the spindle motor portion  52  through the disk drive base  16 . The spindle motor portion  52  may further define the exterior facing cavity  42 . The weight plate  36  may include a notched section  54  with the notched section  54  disposed adjacent to the spindle motor portion  52 . 
     The present embodiment of the invention recognizes that the including of the weight plate  36  with the disk drive  10  modifies the vibration characteristics of the disk drive  10  as the weight plate  36  adds mass to the disk drive  10  without increasing the overall disk drive form factor. In this regard, an increased mass is contemplated to lower a magnitude of self-induced vibration because a greater mass results in a lower acceleration for a given force. In addition, an increased mass is contemplated to generally mitigate a magnitude of vibration due to externally applied forces in a disk drive operating environment. The weight plate  36  may be formed of various materials which may be chosen from those which are well known to one of ordinary skill in the art. For example, the weight plate  36  may be formed of a metal material, such as a steel material. This may be a relatively heavy and low cost material such as a cast steel material. 
     Referring now to  FIGS. 9 and 10 , there is depicted a weight plate  56  according to another embodiment.  FIG. 9  is a plan view of an outer surface  58  of the weight plate  56 .  FIG. 10  is a plan view of an inner surface  60  of the weight plate  56 . In this embodiment, it is contemplated that the weight plate  56  has a mass different than a mass of the weight plate  36 . In this regard, the weight plate  56  may be formed of a material different than that of the weight plate  36 , but nonetheless may be of the same dimensions. 
     The weight plates  36  and  56  are shown as being generally flat. In contrast, referring now to  FIG. 11  there is depicted a weight plate  62  according to another embodiment. Depicted is a perspective view of an inner surface  64  of the weight plate  62 . In this regard, the inner surface  64  is cooperatively formed with the exterior bottom side  38  of the disk drive base  16 . The exterior bottom side  38  may include a structural honeycomb contour. As such the inner surface  64  is complementarily formed so as to interlock with the exterior bottom side  38 . In this embodiment, it is contemplated that the weight plate  62  is formed of a same material as that of the weight plate  36 . The weight plate  62 , however, has a significantly greater mass than that of the weight plate  36  as its dimensions take advantage of the contour of the exterior bottom side  38 . Further in this embodiment, the weight plate  62  is press-fit attached to the disk drive base  16 . Adhesives and fasteners may additionally be used. 
     Referring now to  FIG. 12  there is depicted another embodiment.  FIG. 12  is a perspective view of a disk drive base  68  similar to that of the disk drive base  16 . However, in this embodiment the disk drive base  68  includes a cavity  70  having an exterior bottom side  72  that is generally flat. The weight plate  36  or  56  may be efficiently attached to the disk drive base  68  at the exterior bottom side  72  through the use of an adhesive. 
     According to another aspect of the present invention, there is provided the disk drive  10 . The disk drive  10  includes the disk drive base  16 . The disk drive base  16  includes an exterior bottom side  38 , the bottom peripheral edge  40  disposed about the exterior bottom side  38 , and the exterior facing cavity  42  formed in the disk drive base  16  defined by the exterior bottom side  38 . The disk drive  10  further includes the weight plate  36  attached to the disk drive base  16  within the exterior facing cavity  42 . The cavity  42  defines a cavity cross sectional area aligned with the bottom peripheral edge  40 , and the weight plate  36  extends substantially across an entirety of the cavity cross sectional area. 
     According to an aspect of the present invention, there is provided a method of fabricating disk drives. The method includes providing disk drives based upon a first disk drive configuration. The first disk drive configuration includes an operable disk drive, such as disk drive  10 . As used herein, the term operable in the context of an operable disk drive refers to a disk drive that is capable of performing a data storage function. The disk drive  10  includes the disk drive base  16  with the exterior bottom side  38 , and a first weight plate, such as weight plate  36 , attached to the exterior bottom side  38  of the disk drive base  16 . The method further includes providing disk drives based upon a second disk drive configuration. The second disk drive configuration includes the operable disk drive, such as disk drive  10 , and a second weight plate, such as weight plate  56 , attached to the exterior bottom side  38  of the disk drive base  16 . The weight plate  56  has a mass different than a mass of the weight plate  36 . 
     It is contemplated the first and second disk drive configurations have differing vibration characteristics as their respective masses are different. This enables a disk drive manufacturer to cost effectively provide disk drives based upon a common disk drive base while having the overall disk drive conform to differing vibration specifications through the use of the weight plates  36 ,  56 . As such, the first and second disk drive configurations may have comparable data storage and retrieval performance while exhibiting substantially different vibration characteristics. Thus, the first and second disk drive configurations may be utilized for differing applications, such as for a personal computer and a set top audio visual application. The first disk drives may be provided to a first customer, and the second disk drives may be provided to a second customer. In another arrangement, the first disk drives and the second disk drives are provided to a same customer. 
     According to another aspect of the present invention, there is provided another method of fabricating disk drives. The method includes providing disk drives based upon a first disk drive configuration. The first disk drive configuration includes an operable disk drive, such as disk drive  10 , including the disk drive base  16  with the exterior bottom side  38 , and a weight plate, such as weight plate  36 , attached to the exterior bottom side  38  of the disk drive base  16 . The method further includes providing disk drives based upon a second disk drive configuration. The second disk drive configuration includes the operable disk drive, such as disk drive  10 . The disk drive base  16  is exposed without any weight plate attached to the exterior bottom side  38 . The first disk drives may be provided to a first customer, the second disk drives may be provided to a second customer. In another arrangement, the first disk drives and the second disk drives are provided to a same customer. 
     Referring now to  FIG. 13  (PRIOR ART) is a exploded perspective view similar to that of  FIG. 2 , however, with a prior art disk drive  74  including an electromagnetic shield  76  attached to a disk drive base  80 . The disk drive base  80  includes a bottom peripheral edge  82  that defines a disk drive form factor. The disk drive  80  further includes a cavity  84  formed in the disk drive base  80  adjacent the peripheral outer edge  82 . For ease of discussion the prior art disk drive  74  includes the printed circuit board  14 .  FIG. 14  (PRIOR ART) is a cross sectional side view of the disk drive base  84  as seen along axis  14 - 14  of  FIG. 13  as shown with the electromagnetic shield  76  disposed within the cavity  84 . The electromagnetic shield  76  includes an outer surface  78 . The electromagnetic shield  76  is utilized to shield electromagnetic waves associated with the disks stored within the disk drive  74 . As such, the electromagnetic shield  76  is generally c-shaped following the contour of the disks within the disk drive  74 . Various notches are disposed in the electromagnetic shield  76  to accommodate various fasteners. The electromagnetic shield  76  is a relatively thin piece of metal material. In this regard, the outer surface  78  is significantly below the peripheral outer edge  82  well within the disk drive form factor.