Abstract:
A hard disk drive (HDD) and method, with the HDD including a housing, having a base member and a cover member attached to each other, a plurality of disks, rotatably stacked on the base member and spaced apart from one another, an actuator installed on the base member to rotate around a pivot and fixedly supporting, on its leading end, a slider on which a magnetic head for recording or reproducing data to or from the disks is mounted, and a damper, disposed between the stacked disks, wherein a groove is formed on surfaces of the damper facing the disks.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the priority benefit of Korean Patent Application No. 2004-51976, filed on Jul. 5, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a hard disk drive (HDD), and more particularly, to an HDD and method for suppressing turbulence during the rotation of a HDD disk.  
         [0004]     2. Description of the Related Art  
         [0005]     Hard disk drives (HDDs), which are auxiliary memory devices for computers, reproduce information stored in a magnetic disk or record new information on the magnetic disk by way of a magnetic head. There have been demands for HDDs to have higher capacity and operate at higher speeds with lower vibrations. To meet these demands, extensive research and development efforts have been made.  
         [0006]      FIG. 1  is an exploded perspective view of a conventional HDD disclosed in Korean Patent Publication No. 2003-68261.  
         [0007]     Referring to  FIG. 1 , a HDD  10  includes a pair of disks  20  and  22 , which are data recording media having a spacer  25  therebetween, a spindle motor  30  that is installed on a base member  11  and rotates the disks  20  and  22 , an actuator  40  that includes a magnetic head (not shown) for recording or reproducing data on the disks  20  and  22  and for moving the magnetic head, and a cover member  15  that is attached to the base member  11  to protect the disks  20  and  22 , the spindle motor  30 , and the actuator  40  on the base member  11 .  
         [0008]     The disks  20  and  22  are fixed on a rotor of the spindle motor  30  so as to rotate relative to the base member  11 . Servo signals indicating positions of data recorded or to be recorded are previously recorded on tens of thousands of tracks on surfaces of the respective disks  20  and  22  along the circumferences of the disks  20  and  22 .  
         [0009]     The actuator  40 , which is driven by a voice coil motor  48 , rotates around a pivot bearing  47  that is installed on the base member  11 . The actuator  40  includes a swing arm  42  that is pivotably coupled to the pivot bearing  47 , and a suspension  43  that elastically biases a slider  45 , on which the magnetic head is mounted, toward the surfaces of the respective disks  20  and  22 .  
         [0010]     If the HDD  10  is turned on and the disks  20  and  22  begin to rotate, a lifting force is generated due to an air pressure difference. Accordingly, the slider  45  is maintained over the surfaces of the respective disks  20  and  22  at a height where the lifting force generated from the rotation of the disks  20  and  22  is equal to an elastic force of the suspension  43 . Consequently, the magnetic head mounted on the slider  45  records or reproduces data on the disks  20  and  22  while maintaining a predetermined distance from the respective disks  20  and  22 .  
         [0011]     As such, the conventional HDD  10  suffers from vibrations due to structural defects of the spindle motor  30 , assembly errors of the disks  20  and  22 , and turbulent air flow in the HDD  10 , for example. Such vibrations cause position error signals (PESs) and negatively affect recording and reproducing operations of the HDD  10 .  
         [0012]     A recent attempt to use a hydrodynamic bearing in the spindle motor  30  of the HDD has considerably reduced vibrations in comparison to spindle motors using ball bearings. Accordingly, turbulent air flow from the high speed rotation of the disks  20  and  22  has become the primary cause of vibrations of the HDD  10 . Several approaches have been made to suppress the turbulent air flow, for example, by forming grooves  12  and  16  on surfaces of the base member  11  and the cover member  15 , which face the disks  20  and  22 , respectively. Another method includes forming a blade (not shown). However, if the grooves  12  and  16  or the blade is applied to the HDD  10  as shown in  FIG. 1 , the grooves  12  and  16  or the blade would still only fail to control the air flow between the inner surfaces of the disks  20  and  22 , which do not respectively face the base member  11  and the cover member  15 . In addition, neither grooves  12  and  16 , nor the blade, suppress vibrations of the actuator  40 .  
       SUMMARY OF THE INVENTION  
       [0013]     The present invention provides a hard disk drive (HDD), which prevents turbulence by disposing a damper, on which grooves are formed, between stacked disks.  
         [0014]     Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
         [0015]     To achieve the above and/or other aspects and advantages, embodiments of the present invention set forth a hard disk drive including a housing including a base member attached to a cover member, a plurality of disks rotatably stacked on the base member and spaced apart from one another, an actuator pivotably installed on the base member and fixedly supporting, on its leading end, a slider on which a magnetic head for recording or reproducing data to or from the disks is mounted, and a damper disposed between two of the plurality of stacked disks, wherein a groove is formed on at least one surface of the damper respectively facing at least one of the two disks.  
         [0016]     A depth of the groove may range from 1/10 to ⅓ of a thickness of the damper or a width of the groove may range from 1/20 to 3/20 of a width of the damper. In addition, a plurality of adjacent grooves may be formed on the at least one surface of the damper, and a gap between the adjacent grooves may range from 1/10 to ½ of the width of the damper.  
         [0017]     Further, if a rotational axis of the at least one disk is chosen as an origin and a pair of virtual straight lines intersecting each other are drawn to divide a corresponding plane into four sections, a center of curvature of the groove is positioned in a quadrant symmetric with respect to an origin to a quadrant in which a pivot axis of the actuator is positioned and a radius of curvature of the groove is greater than a radius of the disk. An angle formed between a tangent line contacting an outer peripheral surface of the damper at the groove and a line extending a terminal end of the groove that meets the tangent line may range from 10 to 45 degrees.  
         [0018]     The damper may be mounted on the base member so as to not contact the two disks or disturb the rotation of the actuator. The damper may have a “C” shape thereby facing only a portion of the surface area of the respective at least one of the two disks. Accordingly, the groove can suppress turbulence generated by the rotation of at least one of the two disks. The groove may also be one of a plurality of radial grooves suppressing turbulence.  
         [0019]     The plurality of radial grooves may be formed only on a portion of the damper adjacent to the actuator. The plurality of radial grooves may also be formed only on a portion of the damper not adjacent to the actuator.  
         [0020]     To achieve the above and/or other aspects and advantages, embodiments of the present invention set forth a disk drive turbulence suppression method, including rotating a plurality of disks rotatably stacked on a base member and spaced apart from one another, and dampening turbulence between at least two of the plurality of stacked disks, comprising channeling air through at least one groove formed on at least one surface of at least one damper respectively facing at least one of the two disks.  
         [0021]     The disk drive may be a hard disk drive. Further, the method may include pivoting an actuator fixedly supporting, on its leading end, a slider on which a magnetic head for recording or reproducing data to or from at least one of the plurality of disks is mounted.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]     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:  
         [0023]      FIG. 1  illustrates an exploded perspective view of a conventional hard disk drive (HDD);  
         [0024]      FIG. 2  illustrates an exploded perspective view of an HDD, according to an embodiment of the present invention;  
         [0025]      FIG. 3  illustrates a plan view of a damper for the HDD shown in  FIG. 2 , according to an embodiment of the present invention;  
         [0026]      FIG. 4  illustrates a sectional view of the HDD shown in  FIG. 2 ;  
         [0027]      FIG. 5  illustrates plan views of a conventional HDD and various embodiments of the present invention, adopted for turbulence comparison using a computational fluid dynamics (CFD) program; and  
         [0028]      FIGS. 6 and 7  illustrate graphs of CFD results for the HDDs illustrated in  FIG. 5 , wherein  FIG. 6  illustrates turbulence in an inlet line and  FIG. 7  illustrates turbulence in an outlet line. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]     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.  
         [0030]      FIG. 2  illustrates an exploded perspective view of a hard disk drive (HDD), according to an embodiment of the present invention. Similarly,  FIG. 3  illustrates a top plan view of a damper for the HDD shown in  FIG. 2 , and  FIG. 4  illustrates a sectional view of the HDD shown in  FIG. 2 .  
         [0031]     Referring to  FIGS. 2 and 4 , a HDD  100  includes a housing, formed by attaching a cover member  105  to a base member  101 , with a predetermined inner space therein. First and second disks  110  and  112 , a spindle motor  120 , an actuator  130 , and a damper  150  reside within the housing.  
         [0032]     The housing includes the base member  101  that supports the spindle motor  120  and the actuator  130 , and the cover member  105  which is attached to the base member  101  to protect the disks  110  and  112 . The housing is generally made of stainless steel or aluminium.  
         [0033]     The first and second disks  110  and  112  are mounted inside the housing. Four or more disks have been mounted in a HDD in order to increase data storage capacity, but with the recent drastic increase in surface recording density, one or two disks can store a sufficient amount of data. Accordingly, HDDs having only one or two disks have been mainly used in recent years.  
         [0034]     The spindle motor  120  rotates the first and second disks  110  and  112 , and is fixed on the base member  101 . A ring-shaped spacer  122  is inserted between the first and second disks  110  and  112  to maintain a space between the two disks  110  and  112 . A disk clamp  125  is screwed to a top portion of the spindle motor  120  to prevent separation of the disks  110  and  112 .  
         [0035]     The actuator  130  is used to record or read data on the disks  110  and  112 , and is pivotably installed on the base member  101 . The actuator  130  includes a swing arm  132  rotating around a pivot bearing  137 , first through fourth suspensions  133   a,    133   b,    133   c,  and  133   d  coupled to a leading end portion of the swing arm  132 , and first through fourth sliders  135   a,    135   b,    135   c,  and  135   d,  supported by the suspensions  133   a,    133   b,    133   c,  and  133   d,  respectively. First through fourth magnetic heads  136   a,    136   b,    136   c,  and  136   d,  for recording and reproducing data, are mounted on the sliders  135   a,    135   b,    135   c,  and  135   d,  respectively. Further, a voice coil motor (VCM)  138  provides a rotating force for rotating the swing arm  132  around the pivot bearing  137 . The VCM  138  can be controlled by a servo control system, and rotates the swing arm  132  in a direction defined by Fleming&#39;s Left Hand Rule due to an interaction between current input to a VCM coil and a magnetic field formed by magnets. Accordingly, the four sliders  135   a,    135   b,    135   c,  and  135   d,  attached to leading ends of the suspensions  133   a,    133   b,    133   c,  and  133   d, respectively, are moved over the first and second disks  110  and  112  toward the spindle motor  120  or toward outer peripheries of the disks  110  and  112 .    
         [0036]     The HDD  100  according to embodiments of the present invention employs a damper  150 , which is disposed between the rotating disks  110  and  112  to suppress vibrations and noise caused by the rotation of the disks  110  and  112 . Upper and lower grooves  152  and  153  are formed on top and bottom surfaces of the damper  150 , respectively facing the disks  110  and  112 . The damper  150  can be made of metal, such as aluminium, and is mounted on the base member  101  so as to not contact the disks  110  and  112 . Further, the damper  150  is out of the scope of activity of the actuator  130 , so as not to disturb the rotation of the actuator  130 , and has a “C” shape, thereby facing about half of the surface areas of the respective disks  110  and  112 .  
         [0037]     Focusing on  FIG. 4 , it is preferable that a depth D of the respective grooves  152  and  153  range from 1/10 to ⅓ of a thickness T of the damper  150 . The grooves  152  and  153  guide air flow, which rotates counterclockwise, shown by an arrow in  FIG. 3 , to suppress turbulence generated by the rotation of the disks  110  and  112 . If the depth D of the grooves  152  and  153  is less than 1/10 of the thickness T of the damper  150 , the grooves  152  and  153  cannot guide the air flow satisfactorily, and if the depth D is greater than ⅓ of the thickness T, the stiffness of the damper  150  deteriorates.  
         [0038]     In addition, it is preferable, though not necessary, that a width Wg of the respective grooves  152  and  153  range from 1/20 to 3/20 of a width Wd of the damper  150 . If the width Wg of the grooves  152  and  153  is less than 1/20 of the width Wd of the damper  150 , the grooves  152  and  153  cannot guide the air flow satisfactorily, and if the width Wg is greater than 3/20 of the width Wd, the stiffness of the damper  150  may deteriorate.  
         [0039]     Also, it is preferable, though not necessary, that a plurality of grooves  152   a  through  152   d,  of grooves  152 , be formed on the top surface of the damper  150  and a plurality of grooves  153   a  through  153   d,  of grooves  153 , be formed on the bottom surface of the damper  150 , with a gap G between adjacent grooves ranging from 1/10 to ½ of the width Wd of the damper  150 . If the gap G between the adjacent grooves is less than 1/10 of the width Wd of the damper  150 , the stiffness of the damper  150  may deteriorate, and if the gap G is greater than ½ of the width Wd, the number of grooves is reduced and thus the grooves  152  and  153  cannot guide the air flow satisfactorily.  
         [0040]     Referring to  FIG. 3 , if the spindle motor  120 , which functions as a rotational axis for the disks  110  and  112 , is chosen as the origin and a pair of virtual straight lines, which are perpendicular to a side surface of the base member  101  and perpendicularly intersect each other, are drawn to divide a plane on which the grooves  152  and  153  are formed into four sections, it is preferable that a center of curvature C of the grooves  152  and  153  be in a quadrant symmetric with respect to the origin to a quadrant in which the pivot bearing  137 , which functions as a pivot axis of the actuator  137 , is positioned, and a radius of curvature of the grooves  152  and  153  be greater than a radius of the disks  110  and  112 . The air flow rotating counterclockwise, as shown by the arrow, is formed on the surfaces of the disks due to the rotation of the disks  110  and  112 . The guidance of the air flow to the spindle motor  120 , which is the rotational axis of the disks  110  and  112 , depends on the shapes of the grooves  152  and  153 .  
         [0041]     Furthermore, it is preferable, though not necessary, that an angle A formed between a tangent line P 1  contacting an outer peripheral surface of the damper  150  at a terminal end of a groove and an extension line P 2  of the terminal end of the groove that meets the tangent line P 1  range from 10 to 45 degrees. If the angle A is less than 10 degrees, the grooves  152  and  153  may not satisfactorily guide the counterclockwise air flow to the spindle motor  120 , and if the angle A is greater than 45 degrees, the counterclockwise air flow can be disturbed, thereby causing turbulence.  
         [0042]     A computational fluid dynamics (CFD) analysis was performed to verify the effects of embodiments of the present invention.  FIG. 5  illustrates plan views of a conventional HDD and various embodiments of the present invention, adopted for turbulence comparison using CFD.  FIGS. 6 and 7  illustrate graphs of the CFD results for the HDDs illustrated in  FIG. 5 , with  FIG. 6  illustrating the turbulence in an inlet line, and  FIG. 7  illustrating the turbulence in an outlet line.  
         [0043]     Referring to  FIG. 5 , an HDD Default includes a damper, which is disposed between a plurality of disks, having no grooves thereon. A HDD Type #1 includes a damper on which radial grooves are formed, a HDD Type #2 has radial grooves formed only on a portion, adjacent to an actuator, of a damper, a HDD Type #3 has radial grooves formed only on a portion of a damper far away from an actuator, and a HDD Type #4 is the HDD, according to embodiments of the present invention illustrated in  FIGS. 2 through 4 . Further, a HDD Type #5 is similar to the HDD Type #4, but has grooves formed over a wider area, and a HDD Type #6 is similar to the HDD Type #4 but has a greater angle formed between the tangent line contacting the outer peripheral surface of a damper at a groove and the line extending the terminal end of the groove meeting the tangent line.  
         [0044]     It is assumed that a virtual line positioned before the air flow enters the damper in the HDDs Default is an inlet line L 1  and a virtual line positioned after the air flow goes out of the damper is an outlet line L 2 , as illustrated in  FIG. 2 . In the same manner, it is assumed that a virtual line positioned before the airflow enters the damper in each of the HDDs Types #1 through #6 is an inlet line L 1  and a virtual line positioned after the airflow goes out of the damper is an outlet line L 2 . Turbulence in the inlet line and the outlet line of each HDD was calculated using CFD analysis under the following conditions. 
        1) Angular velocity of disk: 7200 rpm     2) Operating condition: 1 atm, room temperature     3) Fluid type: air (dynamic viscosity coefficient υ=0.15 cm 2 /s)     4) Analyzed as a steady state (Energy equatin is ignorable)     5) k-ε RNG 3D Model of turbulence        
 
         [0050]     The graphs of  FIG. 6  illustrate turbulence intensity (TI) in the inlet line of each HDD obtained through CFD analysis, and the graphs of  FIG. 7  illustrate TI in the outlet line of each HDD obtained through CFD analysis. In the graphs, ID represents an inner disk closer to a rotational axis of the disks, MD represents a middle disk, and OD represents an outer disk farther from the rotational axis. Heads #0, #1, #2, and #3 represent a lowermost head through an uppermost head, respectively. Here, the TI is calculated by dividing the fluid velocity fluctuation by its mean value.  
         [0051]     In order to more easily grasp the results shown in  FIGS. 6 and 7 , Tables 1 through 3 are provided below. In Tables 1 and 2, “TI average” represents an average value of the TI&#39;s of each of the HDDs Default and Types #1 through #6 in the graphs of  FIGS. 6 and 7 , and “Change Rate” is defined as follows:  
         Change   ⁢           ⁢   rate   ⁢           ⁢     (   %   )       =         TI   ⁢           ⁢   avg   ⁢           ⁢   of   ⁢           ⁢   default     -     TI   ⁢           ⁢   avg   ⁢           ⁢   of   ⁢           ⁢   type         TI   ⁢           ⁢   avg   ⁢           ⁢   of   ⁢           ⁢   default           
 
         [0052]     Further, “Standard Deviation” in Tables 1 and 2 is a standard deviation for each of the HDDs Default and Types #1 through #6.  
                                                                                 TABLE 1                       Inlet line   Default   Type #1   Type #2   Type #3   Type #4   Type #5   Type #6                                Head   TI   194.7657   186.5883   190.8714   189.5981   192.944   191.463   191.1437       #0   average           Change   0   −4.19857   −1.99949   −2.65322   −0.93533   −1.69572   −1.85967           rate           Standard   31.51302   24.19299   27.91278   28.62776   27.53196   28.35418   27.03744           deviation       Head   TI   183.9201   178.3078   175.8674   176.2308   174.6578   177.5943   174.7703       #1   average           Change   0   −3.05149   −4.37839   −4.18081   −5.03608   −3.43941   −4.97486           rate           Standard   43.12308   46.98242   46.52182   41.78871   43.54715   44.85232   49.28575           deviation       Head   TI   183.6983   177.1293   180.2242   179.6015   178.3967   181.5897   178.7589       #2   average           Change   0   −3.57593   −1.89119   −2.23014   −2.88599   −1.14784   −2.68884           rate           Standard   46.01325   46.19382   47.72139   44.15274   45.27681   45.81867   50.11549           deviation       Head   TI   201.9355   193.0813   196.9622   196.01   196.9125   197.277   197.1743       #3   average           Change   0   −4.38468   −2.46281   −2.93433   −2.48743   −2.30692   −2.35775           rate           Standard   31.76105   32.79144   31.33942   29.77226   31.67933   31.59205   30.95772           deviation                  
 
         [0053]    
       
         
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
               
               
                 Outlet line 
                 Default 
                 Type #1 
                 Type #2 
                 Type #3 
                 Type #4 
                 Type #5 
                 Type #6 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Head 
                 TI 
                 171.338 
                 164.5775 
                 163.1553 
                 166.0281 
                 165.2523 
                 163.8397 
                 163.6395 
               
               
                 #0 
                 average 
               
               
                   
                 Change 
                 0 
                 −3.94575 
                 −4.77577 
                 −3.09911 
                 −3.55191 
                 −4.37635 
                 −4.49319 
               
               
                   
                 rate 
               
               
                   
                 Standard 
                 68.65598 
                 64.48043 
                 68.04785 
                 65.66888 
                 64.87574 
                 66.06996 
                 66.32221 
               
               
                   
                 deviation 
               
               
                 Head 
                 TI 
                 144.0742 
                 147.0712 
                 143.3129 
                 141.2875 
                 138.1034 
                 139.6185 
                 140.633 
               
               
                 #1 
                 average 
               
               
                   
                 Change 
                 0 
                 2.080199 
                 −0.52836 
                 −1.93421 
                 −4.14424 
                 −3.09263 
                 −2.38845 
               
               
                   
                 rate 
               
               
                   
                 Standard 
                 106.8203 
                 98.93155 
                 95.10034 
                 94.68.54 
                 96.33217 
                 95.53991 
                 96.38253 
               
               
                   
                 deviation 
               
               
                 Head 
                 TI 
                 153.8928 
                 154.68 
                 154.4524 
                 151.3695 
                 149.0257 
                 151.0179 
                 154.9267 
               
               
                 #2 
                 average 
               
               
                   
                 Change 
                 0 
                 0.511502 
                 0.36359 
                 −1.63964 
                 −3.16265 
                 −1.86814 
                 0.671799 
               
               
                   
                 rate 
               
               
                   
                 Standard 
                 107.0405 
                 94.29507 
                 97.02284 
                 95.98765 
                 95.41825 
                 94.12437 
                 96.13367 
               
               
                   
                 deviation 
               
               
                 Head 
                 TI 
                 149.4425 
                 139.0238 
                 139.3473 
                 136.5383 
                 136.5859 
                 137.7741 
                 138.4413 
               
               
                 #3 
                 average 
               
               
                   
                 Change 
                 0 
                 −6.97171 
                 −6.75523 
                 −8.63492 
                 −8.60307 
                 −7.80799 
                 −7.3615 
               
               
                   
                 rate 
               
               
                   
                 Standard 
                 82.50806 
                 78.68553 
                 79.4718 
                 79.5611 
                 81.12308 
                 80.07377 
                 78.76237 
               
               
                   
                 deviation 
               
               
                   
               
             
          
         
       
     
         [0054]    
       
         
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
               
               
                   
                 Default 
                 Type #1 
                 Type #2 
                 Type #3 
                 Type #4 
                 Type #5 
                 Type #6 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Sum of change 
                 0 
                 −23.5364 
                 −22.4277 
                 −27.3064 
                 −30.8067 
                 −25.735 
                 −25.4525 
               
               
                 rates 
               
               
                   
               
             
          
         
       
     
         [0055]     It can be seen from Tables 1 through 3 that a “sum of change rates” for each of the HDDs Types #1 through #6 is smaller than that of the HDD Default. This means that less turbulence is created in the air flow in the HDDs Types #1 through #6, and accordingly, it can be expected that vibrations of the disks and actuator will similarly be reduced.  
         [0056]     In particular, a sum of the HDD Type #4 is over 30% lower than that of the HDD Default, and a sum of each of the other remaining HDDs is 3-8% lower than that of the HDD Default. Additionally, it can be seen that change rates at the heads #1 and #2 are the minimum values. Accordingly, it can be appreciated that the HDD Type #4 is superior to the other HDDs, Default and Types #1, #2, #3, #5, and #6. Specifically, the HDD Type #4 is superior in suppressing turbulent air flow between inner surfaces of the disks, which do not face a base member and a cover member.  
         [0057]     As described above, since the HDD, according to embodiments of the present invention, reduces the turbulence in the air flow inside the housing, vibrations of the disks and the actuator can be reduced. Consequently, position error signals can similarly be reduced, and data recording and reproducing operations of the HDD will be improved.  
         [0058]     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. For example, the HDD may have a plurality of disks, and dampers with grooves may be disposed between two adjacent disks of the plurality of disks. Accordingly, the scope of the present invention is defined only by the appended claims.