Patent Publication Number: US-2006002006-A1

Title: Hard disk drive and method adopting damping member with open-cell structure

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the priority of Korean Patent Application No. 10-2004-0051803, filed on Jul. 3, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      Embodiments of the present invention relate to a hard disk drive (HDD), and more particularly, to a housing for a HDD that can prevent a damping plate, absorbing external shocks and internal noises, from being caused to contact a cover member.  
      2. Description of the Related Art  
      Hard disk drives (HDDs), which store information for computers, read or write data on a disk using a read/write head. In HDDs, the read/write head operates by being moved by an actuator to a desired position a predetermined height above a recording surface of the rotating disk.  
      HDDs include a spindle motor, one or more data storage disks mounted on the spindle motor, and an actuator for moving a read/write head for reading and writing data to a predetermined position on the disks.  
      The disks, the spindle motor, and the actuator can be enclosed by a housing having a base member and a cover member. The base member and the cover member can be assembled using a plurality of fastening screws. A gasket is inserted between the base member and the cover member to prevent dust or humidity from entering the HDD.  
      The housing of the HDD has a typical structure capable of absorbing external shocks and internal noises. Specifically, a thin damping plate made of stainless steel can be installed on a top surface of the cover member, and the damping plate can be spaced a predetermined distance from the top surface of the cover member by a buffer member. Accordingly, an air-gap is formed between the damping plate and the cover member. The air-gap can reduce noises inside the HDD and also act as an air damper for absorbing shocks applied to the damping plate. The buffer member is typically made of a viscoelastic material, such as nitrile butadiene rubber (NBR), and absorbs and attenuates shocks transmitted to the cover member from the damping plate.  
      The HDD constructed as above is typically subjected to a cleaning process during its assembling process. After the cleaning process, the HDD is subjected to a drying process, which is performed in a vacuum state in order to promote dry efficiency. During the vacuum drying process, air leaks out of the air-gap due to the high difference of air pressures inside and outside the air-gap, thereby forming an even lower air pressure inside the air-gap. After the drying process is completed, the damping plate may become warped toward the cover member, due to an air pressure difference between the inside of the air-gap at the low air pressure and the outside of the air-gap, having recovered to a normal air pressure, thereby causing the damping plate to buckle against the top surface of the cover member.  
      Further, the completely assembled HDD may be subjected to an altitude test. Since the altitude test is performed under various air pressure conditions, air inside the air-gap may leak out, again due to the difference of air pressures inside and outside the air-gap, thereby again causing the damping plate to be pressed to contact the cover member.  
      If the damping plate is warped and becomes pressed to contact the cover member, due to air pressure changes, the air-gap cannot fulfill its desired function, i.e., external shocks applied to the damping plate may be directly transmitted to the cover member. Moreover, since the air-gap cannot attenuate noise inside the HDD, noise emissions also increase.  
     SUMMARY OF THE INVENTION  
      Embodiments of the present invention provide a hard disk drive (HDD), and housing therefore, that prevents a damping plate from buckling against a cover member using a buffer member with an open-cell structure so that an air-gap can absorb external shocks and internal noises.  
      To achieve the above and/or other aspects and advantages, embodiments of the present invention include a hard disk drive housing, including a base member to support a spindle motor, for rotating a data storage disk, and an actuator, having a read/write head, a cover member attached to the base member to enclose the disk, the spindle motor, and the actuator, a damping plate spaced a predetermined distance from a top surface of the cover member to form an air-gap between the damping plate and the cover member, and a buffer member disposed between the cover member and the damping plate and along the circumference of the air-gap to seal the air-gap, wherein the buffer member is made of a material pervious to air but sealed against water.  
      The buffer member may be made of a material having a plurality of cells having of open-cells and closed-cells. The material may be polyurethane foam.  
      In addition, a percentage of the open-cells in the plurality of cells may range from 20 to 50%. The percentage of the open-cells in the plurality of cells may be is about 30%.  
      To achieve the above and/or other aspects and advantages, embodiments of the present invention include a hard disk drive, including a spindle motor for rotating a storage disk, an actuator having a read/write head, a base member to support the spindle motor and the actuator, a cover member attached to the base member to enclose the disk, the spindle motor, and the actuator, a damping plate spaced a predetermined distance from a top surface of the cover member to form an air-gap between the damping plate and the cover member, and a buffer member disposed between the cover member and the damping plate and along the circumference of the air-gap to seal the air-gap, wherein the buffer member is made of a material pervious to air but sealed against water.  
      To achieve the above and/or other aspects and advantages, embodiments of the present invention include a housing protection method for a hard disk drive, including forming an air gap between a damping plate, supporting a spindle motor rotating a data storage disk and an actuator having a read/write head with a base member, and a cover member, encompassing the spindle motor and the actuator with a cover member coupled to the base member, with the damping plate separated a predetermined distance from an upper surface of the cover member, sealing the air gap with a buffer member disposed between the cover member and the damping plate and along the circumference of the air-gap, sealing the air-gap by the buffer member being a material pervious to air but sealed against water.  
      The sealing of the air-gap may further include equalizing pressure within the air-gap and a pressure outside the air gap.  
      Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:  
       FIG. 1  is an exploded perspective view of a hard disk drive (HDD), according to an exemplary embodiment of the present invention;  
       FIG. 2  is a partial sectional view of a housing, e.g., as shown in  FIG. 1  according to an embodiment of the present invention; and  
       FIG. 3  is a view illustrating a structure of a buffer member, e.g., as shown in  FIGS. 1 and 2 , according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.  
       FIG. 1  is an exploded perspective view of a hard disk drive (HDD), according to an exemplary embodiment of the present invention.  FIG. 2  is a partial sectional view of the housing shown in  FIG. 1 .  FIG. 3  is a view illustrating a structure of a buffer member shown in  FIGS. 1 and 2 .  
      Referring to  FIGS. 1 and 2 , the HDD includes a data storage disk  120 , a spindle motor  130  for rotating the disk  120 , and an actuator  140  for moving a read/write head to a predetermined position over the disk  120 . The disk  120 , the spindle motor  130 , and the actuator  140  are enclosed and protected by a housing  110 .  
      One or more disks  120 , which are data recording media, are mounted on the spindle motor  130  and are rotated by the spindle motor  130 . A parking zone  121  on which the read/write head is parked when the HDD stops running is formed on an inner circumferential side of the disk  120 , and a data zone  122 , where data is recorded, formed on an outer circumferential side of the disk  120 .  
      The actuator  140  moves the read/write head, for writing or reading data on the disk  120 , to a predetermined position over the disk  120 , and is pivotably installed on a base member  111  of the housing  110 . Specifically, the actuator  140  includes a swing arm  144  rotatably coupled to a pivot  142  installed on the base member  111 , a suspension  146  installed on an end portion of the swing arm  144  and adapted to elastically bias a slider  148  on which the read/write head is mounted toward a surface of the disk  120 , and a voice coil motor (VCM)  150  for rotating the swing arm  144 .  
      The VCM  150  is controlled by a servo control system, and rotates the swing arm  144  in a direction according to Fleming&#39;s Left Hand Rule, due to an interaction between current input to a VCM coil and a magnetic field formed by magnets. That is, if the HDD is turned on and the disk  120  begins to rotate, the VCM  150  rotates the swing arm  144  clockwise to move the slider  148  with the read/write head thereon from the parking zone  121  to the data zone  122  of the disk  120 . The slider  148  is lifted a predetermined height above the surface of the disk  120  due to a lifting force generated by the rotating disk  120 , and in this state, the head mounted on the slider  148  reads or writes data on the recording surface of the disk  120 . In contrast, if the HDD does not operate, that is, the disk  120  stops rotating, the VCM  150  rotates the swing arm  144  counterclockwise to park the slider  148  with the head in the parking zone  121  of the disk  120 .  
      A method of parking the head includes a contact start stop method (CSS) and a ramp loading method. The ramp loading method installs a ramp (not shown) outside the disks and parks the head on the ramp. Embodiments of the present invention can be applied to HDDs using the ramp loading method as well as the CSS method.  
      The housing  110  includes the base member  111 , on which the disk  120 , the spindle motor  130 , and the actuator  140  are supported, and a cover member  112  attached to the base member  111 , to enclose and protect the disk  120 , the spindle motor  130 , and the actuator  140 . The cover member  112  may be attached to the base member  111  with a plurality of fastening screws  119 . Here, a gasket  113  may be inserted between the base member  111  and the cover member  112  to prevent dust and humidity from entering the HDD. The gasket  113  is typically made of a viscoelastic material, such as rubber, and reduces vibrations of the HDD.  
      The housing  110  may further include a damping plate  115  disposed on a top surface of the cover member  112 , and a buffer member  114 , disposed between the damping plate  115  and the cover member  112 .  
      Specifically, the damping plate  115  can be made of elastic metal. For example, the damping plate  115  may be manufactured by pressing a stainless steel sheet with a thickness of about 1 mm or less into a shape corresponding to the top surface of the cover member  112 . The damping plate  115  manufactured in this way is spaced a predetermined distance from the top surface of the cover member  112 . Accordingly, an air-gap  116  is formed between the damping plate  115  and the cover member  112 . The air-gap  116  can absorb noises inside the HDD to reduce noise emissions, and also acts as an air damper for absorbing shocks applied to the damping plate  115 .  
      The buffer member  114  is disposed between an edge portion of the cover member  112  and an edge portion of the damping plate  115 . The buffer member  114  can take the shape of the circumference of the air-gap  116  formed between the damping plate  115  and the cover member  112 . Top and bottom surfaces of the buffer member  114  can be attached to a bottom surface of the damping plate  115  and the top surface of the cover member  112 , respectively, using a predetermined adhesive, for example.  
      The buffer member  114  absorbs and attenuates shocks transmitted from the damping plate  115  to the cover member  112 .  
      Further, in embodiments of the present invention, the buffer member  114  allows only air to pass between the air-gap  116  and the outside of the HDD. According to embodiments of the present invention the buffer member  114  also functions to maintain an equalized air pressure differential between the air-gap  116  and the outside of the HDD.  
      To this end, according to embodiments of the present invention, the buffer member  114  can be made of a material pervious to air but impervious to water. Specifically, it is preferable, though not necessary, that the buffer member  114  be made of polyurethane foam. As is well known, polyurethane foam is generally preferable since it is a type of foam rubber having excellent shock absorbency and resilience. Further, as shown in  FIG. 3 , the polyurethane foam has a plurality of cells  114   a . The cells  114   a  formed inside the polyurethane foam include closed cells and open-cells. The open-cells have a very small size, and collectively create meandering paths inside the buffer member  114  that are in contact with the air outside the buffer member  114 . Accordingly, air can flow through the buffer member  114  relatively freely via the open-cell paths, but water or foreign substances cannot pass through the buffer member  114 . As a result, according to embodiments of the present invention, the outside of the HDD and the air-gap  116  interact with each other only via air that travels through the buffer member  114 , made of polyurethane foam.  
      The percentage of the open-cells in the plurality of cells  114   a  of the polyurethane foam can be easily adjusted during the manufacturing process of the polyurethane foam. In one embodiment, it is preferable that the percentage of the open-cells be 20 to 50%, and more preferably, about 30%. If the percentage of the open-cells is less than 20%, air cannot flow freely. Conversely, if the percentage of the open-cells is greater than 50%, the density of the polyurethane foam becomes reduced too much, and the shock absorbency of the buffer member  114  may deteriorate.  
      According to embodiments of the present invention, as described above, since the outside of the HDD and the air-gap  116  interact with each other through air via the buffer member  114 , during the vacuum drying process or the altitude test process of the HDD, air pressure inside and outside the air-gap  116  can be kept equalized. Consequently, the conventional problem of the damping plate  115 , buckling against the cover member  112  due to an air pressure difference, can be solved. Thus, the air-gap  116  can fulfil its role in absorbing external shocks and internal noises.  
      As described above, even though external air pressure conditions vary, the air pressure inside and outside the air-gap can be kept equalized by way of the buffer member having the plurality of open-cells, thereby preventing the damping plate from buckling against the cover member. Accordingly, the air-gap formed between the damping plate and the cover member can effectively absorb external shocks and internal noises.  
      While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.