Patent Publication Number: US-2007121243-A1

Title: Spindle motor assembly and hard disk drive having the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of Korean Patent Application No. 10-2005-0101750, filed on Oct. 27, 2005, 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  
      The present general inventive concept relates to a spindle motor assembly and a hard disk drive having the same, and more particularly, to a spindle motor assembly having improved impact resistance and a hard disk drive assembly having the spindle motor assembly.  
      2. Description of the Related Art  
      A hard disk drive is a storage device that records data on a disk or reads the data stored on the data storage disk using a read/write head that approaches a surface of the data storage disk. The read/write head is rotatably mounted on a spindle motor. In order to record or read the data, the read/write head is lifted slightly from a recording surface of the rotating disk and moved to a desired location by an actuator. When the hard disk drive does not operate (i.e., when the hard disk drive does not rotate the disk), the read/write head is parked at a location away from the recording surface of the data storage disk so that the head does not collide with the recording surface when an impact is applied to the hard disk drive. A read/write head parking system used to park the read/write head can be classified as either a contact start stop (CSS) type or a ramp type.  
      In the CSS type parking system, the read/write head is parked in a parking zone disposed at an inner circumference of the data storage disk. In the ramp type parking system, the read/write head is parked on a ramp that is adjacent to an outer circumference of the data storage disk.  
       FIG. 1  illustrates a perspective view of a conventional hard disk drive having the ramp type parking system. Referring to  FIG. 1 , the hard disk drive includes a cover member  11  and a frame member  12  assembled to face each other. The hard disk drive further includes a spindle motor assembly and an actuator  30  accommodated between the cover member  11  and the frame member  12 .  
      The spindle motor assembly includes a data storage disk  50 , a spindle motor  60  on which the data storage disk  50  is mounted to rotate together with the spindle motor  60 , a clamp member  20  for securely fixing the data storage disk  50  onto the spindle motor  60  to rotate the data storage disk  50  together with the spindle motor  60 , and a screw member  55  coupled to the spindle motor  60  via a hole in the clamp member  20 .  
      The actuator  30  includes a swing arm  32  pivotally assembled on an actuator pivot  31 , a suspension  35  mounted on a front end of the swing arm  32 , a read/write head (not shown) mounted on the suspension  35 , and a voice coil motor  40  pivoting the swing arm  32  clockwise or counterclockwise to move the read/write head to a target location of the data storage disk  50 .  
      When the hard disk drive is turned on and the data storage disk  50  starts rotating, the swing arm  32  pivots counterclockwise to load the read/write head on the data storage disk  50 . When the hard disk drive is turned off and the data storage disk  50  stops rotating, the swing arm  32  rotates clockwise to unload the read/write head on a ramp  90  disposed at a location adjacent to an outer circumference of the data storage disk  50 .  
      The ramp type parking system of the hard disk drive minimizes the effect of impact to the hard disk drive. However, an additional component (i.e., the ramp  90 ) has to be mounted in the hard disk drive, which increases the number of work or manufacturing operations. Also, an additional space must be provided in the hard disk drive in which to install the ramp  90 , thereby making an overall size of the hard disk drive larger in order to accommodate the ramp  90 . Furthermore, in order to stably park the read/write head on the ramp  90 , the data can not be stored in an edge region of the data storage disk  50 . This causes a structural limitation in increasing the storage capacity of the data storage disk  50 .  
      On the other hand, the CCS type parking system of a hard disk drive has low manufacturing costs, and a small thickness, weight, and length. However, since the CCS type parking system of the hard disk drive does not minimize the effect of an impact to the hard disk drive, the CCS type hard disk drive cannot be actively used for portable devices.  
     SUMMARY OF THE INVENTION  
      The present general inventive concept provides a spindle motor assembly that has an improved anti-impact property, uses a CCS type parking system that can be manufactured inexpensively, has a compact size, and provides for an increase in a storage capacity of a storage disk. The present general inventive concept also provides a hard disk drive having the spindle motor assembly.  
      Additional aspects of the present general inventive concept 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 general inventive concept.  
      The foregoing and/or other aspects of the present general inventive concept are achieved by providing a spindle motor assembly including a data storage disk to store data and having a parking region in which to park a read/write head, a spindle motor to drive the data storage disk, the spindle motor having a hub around which the data storage disk is fitted, and a clamp member to fix the data storage disk on the hub. The clamp member has a vibration restriction portion formed along a circumferential outer edge thereof to face the parking region to form a marginal gap with a surface of the data storage disk.  
      The clamp member may include a circumferential pressure portion gently protruding toward the surface of the disk and urged to contact the surface of the disk, and the vibration restriction portion extends from the circumferential pressure portion in a radial direction.  
      The spindle motor assembly may further include a damping member disposed on a surface of the vibration restriction portion to face the disk.  
      The damping member may be integrally formed with the clamp member through an injection molding process.  
      The damping member may be formed to have a rim-shape corresponding to the vibration restriction portion and a plurality of coupling protrusions spaced apart from each other by a predetermined distance.  
      The vibration restriction portion may include a plurality of coupling holes in which the respective protrusions of the damping member are fitted.  
      The damping member may be formed of a flexible plastic material.  
      The parking region may be formed on a circumferential inner edge of the disk.  
      The read/write head may be located between the parking region of the disk and the vibration restriction portion of the clamp when the disk stops rotating.  
      The foregoing and/or other aspects of the present general inventive concept are also achieved by providing a spindle motor assembly, including a spindle motor, a disk disposed on the spindle motor and being rotatable by the spindle motor, and a clamp member disposed on the disk to clamp the disk to the spindle motor and having a pressure portion to contact the disk around a circular portion thereof and a vibration restriction portion extending away from the pressure portion along a surface of the disk to define a space with the surface of the disk along an outer circumference of the pressure portion.  
      The foregoing and/or other aspects of the present general inventive concept are also achieved by providing a hard disk drive including an actuator to move a read/write head attached to a front end thereof to a selected location, a data storage disk to store data and having a parking region in which to park the read/write head, a spindle motor to drive the data storage disk and having a hub around which the data storage disk is fitted, and a clamp member to fix the data storage disk on the hub and having a vibration restriction portion formed on a circumferential outer edge thereof, the vibration restriction portion facing the parking region and forming a marginal gap with the disk.  
      The actuator may include a suspension to which the read/write head is attached and having a damping protrusion formed at a front end thereof, a swing arm to support the suspension and to pivot about a pivot axis, and a voice coil motor to drive the swing arm.  
      The damping protrusion may be semi-spherical and may be formed of a flexible plastic material.  
      The foregoing and/or other aspects of the present general inventive concept are also achieved by providing a hard disk drive, including a spindle motor, a disk disposed on the spindle motor, a clamp member disposed on the disk and the spindle motor to clamp the disk to the spindle motor and having a restriction portion extending parallel to the disk around an outer circumference of the clamp member, and a magnetic head assembly having a suspension with a magnetic head disposed thereon that is movable between the restriction portion and the disk. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and/or other aspects of the present general inventive concept 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 a perspective view illustrating a conventional hard disk drive;  
       FIG. 2  is a perspective view illustrating a hard disk drive having a spindle motor assembly according to an embodiment of the present general inventive concept;  
       FIG. 3  is a plane view illustrating an operation of the hard disk drive of  FIG. 2 ;  
       FIG. 4  is a sectional view illustrating the spindle motor assembly of the hard disk drive taken along lines IV-IV of  FIG. 2 ;  
       FIG. 5  is a side view illustrating the hard disk drive of  FIG. 3  as seen from a direction V;  
       FIG. 6  is a perspective view illustrating a damping member and a clamp member of the hard disk drive of  FIG. 2 , according to an embodiment of the present general inventive concept;  
       FIG. 7  is a sectional view illustrating the damping member and the clamp member of the hard disk drive taken along lines VII-VII of  FIG. 6 ; and  
       FIG. 8  is a side view illustrating a portion of a hard disk drive employing the clamp member and the damping member of  FIG. 6 , according to an embodiment of the present general inventive concept. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures.  
       FIG. 2  is a perspective view illustrating a hard disk drive having a spindle motor assembly according to an embodiment of the present general inventive concept. Referring to  FIG. 2 , the hard disk drive includes a data storage disk  150 , a spindle motor  160  to rotate the data storage disk  150 , a clamp member  120  to fix the data storage disk  150  onto the spindle motor  160 , and an actuator  130  to move a read/write head  138  that reads and writes data to and from a predetermined location(s) of the data storage disk  150 . The spindle motor assembly includes the data storage disk  150 , the spindle motor  160 , and the clamp member  120 . The hard disk drive further includes a base member  112  and a cover member  111  to be coupled to each other to house the spindle motor assembly, the actuator  130 , etc.  
      The spindle motor  160  is installed on the base member  112  of the hard disk drive. One or more data storage disks  150  are installed on the spindle motor  160 . The data storage disk  150  is rotated at a predetermined angular velocity by the spindle motor  160 . A parking region P, where the data are not stored, is formed along a circumferential inner edge of the data storage disk  150 . The parking region P is provided to allow the read/write head  138  to be stably seated thereon (i.e., parked) when the data storage disk  150  stops rotating. A plurality of bumps may be evenly distributed on an entire surface of the parking region P so that the read/write head  138  sitting on the surface of the data storage disk  150  can effectively rise above the surface of the data storage disk  150  when the data storage disk  150  starts rotating.  
      The clamp member  120  urges the data storage disk  150  onto the spindle motor  160 . When a screw member  155  is screw-coupled to an upper end of the spindle motor  160  through a central hole  121  of the clamp member  120 , the clamp member  120  contacts the data storage disk  150  with a predetermined pressure. The clamp member  120  includes a vibration restriction portion  125  at an outer portion thereof that corresponds to the parking region P in a vertical direction. The vibration restriction portion  125  will be described later.  
      The actuator  130  includes an actuator pivot  131  installed on the base member  112 , a swing arm  132 , a suspension  135 , the read/write head  138 , a coil supporting unit  145 , and a voice coil motor (VCM) having a VCM coil  141 , a magnet  175 , and a yoke  171 . The swing arm  132  is pivotally coupled to the actuator pivot  131 . The suspension  135  is coupled to a front end of the swing arm  132  to supportably bias the read/write head  138  toward the surface of the data storage disk  150 . The coil supporting unit  145  is provided on a rear end of the swing arm  132 .  
      The voice coil motor provides a driving force to rotate the swing arm  132 . That is, the swing arm  132  pivots about the actuator pivot  131  in a direction according to Fleming&#39;s left-hand rule by an interaction between a current applied to the VCM coil  141  and an electric field formed by the magnet  175 . The VCM coil  141  is assembled on the coil supporting unit  145 . The magnet  175  faces the VCM coil  141 . The magnet  175  is supported on the yoke  171 .  
       FIG. 3  is a plane view illustrating an operation of the hard disk drive of  FIG. 2 .  
      Referring to  FIG. 3 , when the hard disk drive is turned on and the data storage disk  150  starts rotating, the swing arm  132  is pivoted around the actuator pivot  131  in a first direction (for example, clockwise) by the voice coil motor to move the read/write head  138  from the parking region P (see  FIG. 2 ) along the recording surface of the data storage disk  150 . For example, the recording surface of the data storage disk  150  indicates a data region from which the parking region P is excluded. When the data storage disk  150  rotates, an air flow is generated around the data storage disk  150 . The air flow generates a lifting force which raises the read/write head  138  above the recording surface by a predetermined height. In this state, the head  138  records data on the recording surface of the data storage disk  150  or reads the data stored in the recording surface of the data storage disk  150  while following a predetermined track T.  
      Additionally, when the hard disk drive is turned off and the data storage disk  150  stops rotating, the swing arm  132  pivots around the actuator pivot  131  in a second direction opposite to the first direction (for example, counterclockwise) to allow the read/write head  138  to move from the recording surface of the data storage disk  150  and sit in the parking region P formed along the circumferential inner edge of the data storage disk  150 .  
       FIG. 4  is a sectional view illustrating the spindle motor assembly of the hard disk drive taken along lines IV-IV of  FIG. 2 . Referring to  FIG. 4 , the spindle motor  160  includes a shaft  161  installed on the base member  112 , stators  163  fixed on an outer circumference of the shaft  161 , and a rotor such as a hub  165  disposed on an outer side of the stator(s)  163 . The data storage disk  150  is fitted around the hub  165 . The spindle motor  160  has a top central hole to which the screw member  155  is screw-coupled. When the screw member  155  is screw-coupled to the spindle motor  160 , the clamp member  120  is urged toward the data storage disk  150  by a head portion of the screw member  155 . The clamp member  120  has a circumferential pressure portion  123  that is curved and protrudes toward the data storage disk  150  (i.e., downward toward the surface of the data storage disk  150 ). The pressure portion  123  may have a protruding part with a V-shape or a U-shape extending downward from a plane of the clamp member  120 . The protruding part contacts the data storage disk  150  adjacent to where the disk  150  is fitted around the hub  165 . The clamp member  120  contacts the data storage disk  150  while exerting a predetermined pressure as the circumferential pressure portion  123  is resiliently deformed. The vibration restriction portion  125  extends in a radial direction from the circumferential pressure portion  123  and vertically corresponds to the parking region P. In other words, the vibration restriction portion  125  extends in a horizontal direction, while the circumferential pressure portion  123  extends in the vertical direction. A predetermined marginal gap “g” is formed between the vibration restriction portion  125  of the clamp member  120  and the parking region P of the data storage disk  150 . The marginal gap “g” prevents a front end of the suspension  135  to which the read/write head  138  is attached from interfering with the clamp member  120  when the read/write head  138  is moved into or out of the parking region P. The marginal gap “g” may be formed as small as possible within a range not to interfere with the movement of the read/write head  138  such that an effect of impact to the hard disk drive can be minimized. This will be now described in more detail.  
       FIG. 5  is a side view illustrating the hard disk drive of  FIG. 3  as seen from a direction V, when the read/write head  138  is parked in the parking region P of the data storage disk  150  (i.e., between the parking region P of the disk  150  and the vibration restriction portion  125 ). When an impact is vertically applied to the hard disk drive that is not operating (i.e., the read/write head  138  is parked in the parking region P and the data storage disk  150  is not rotating), for example, when an impact is applied to the hard disk drive in a vertical upward direction, the suspension  135  having relatively low strength is biased downward and bounces back by its elastic restoring force in a vertical upward direction. At this point, the read/write head  138  rapidly rises together with the suspension  135  and collides with the vibration restriction portion  125  of the clamp member  120  to generate a repulsive collision force by which the suspension  135  moves again downward. When the marginal gap “g” is not limited within a predetermined range and the suspension  135  repeats the above described movement, the read/write head  138 , being in a standing position, collides with the surface of the data storage disk  150 . Thus, corners of the read/write head  138  collide repeatedly with the surface of the data storage disk  150 . As described above, as the impact concentrates on the corners of the read/write head  138 , the read/write head  138  may be physically damaged and dents may be formed on the surface of the data storage disk  150 .  
      However, in the present embodiment, since the vibration restriction portion  125  extending in the radial direction is formed on the outer circumference of the clamp  120 , an amount of the vertical movement of the read/write head  138  is reduced when the impact is applied. Furthermore, since the marginal gap “g” is narrowly formed (i.e., the marginal gap “g” is within a predetermined range), the read/write head  138  is forcibly maintained parallel to the surface of the data storage disk  150 . Thus, an entire bottom surface instead of the corners of the read/write head  138  of the read/write head  138  collides with the surface of the data storage disk  150 . That is, the collision area between the read/write head  138  and the data storage disk  150  increases. As a result, the damage of the read/write head  138  is prevented and the formation of the dents on the surface of the data storage disk  150  can be reduced or entirely avoided. The predetermined range of the marginal gap “g” may be set to be slightly larger than the read/write head  138  combined with the suspension  135 .  
       FIG. 6  is a perspective view illustrating a damping member  280  and a clamp member  220  according to another embodiment of the present general inventive concept. Referring to  FIG. 6 , the clamp member  220  has a central hole  221  through which the screw member  155  penetrates and a circumferential pressure portion  223  formed around the central hole  221  to extend toward the surface of the disk  150 . A circumferential vibration restriction portion  225  is formed on an outer edge of the clamp member  220  and is elevated upward so that the vibration restriction portion  225  is spaced apart from the surface of the disk  150  by a predetermined height. Similar to the foregoing embodiment, the circumferential vibration restriction portion  225  restricts the vertical vibration of the read/write head  138  that is in a parking state (i.e., in the parking region P) when an impact is applied to the hard disk drive. Thus, the damage of the read/write head  138  and the disk  150  caused by the collision thereof can be prevented.  
      The damping member  280  is coupled to a bottom surface of the clamp member  220 , which faces the surface of the disk  150 . The damping member  280  has a rim-shape corresponding to a circumferential edge of the clamp member  220  and is coupled to a bottom of the circumferential edge of the clamp member  220 . The damping member  280  has a plurality of coupling protrusions  285  spaced apart from each other by a predetermined distance or interval and extending toward the clamp member  220 . The protrusions  285  are fitted in respective coupling holes  228  formed in the clamp member  220 . The damping member  280  may be made of a different material than the clamp member  220 , and may be softer or less rigid than the clamp member  220 .  
       FIG. 7  is a sectional view illustrating the damping member  280  and the clamp member  220  taken along lines VII-VIl of  FIG. 6 . As illustrated in  FIG. 7 , side surfaces of each coupling projection  285  may be obliquely inclined so as not to be released from the respective corresponding coupling hole  228 .  
       FIG. 8  is a side view illustrating a portion of a hard disk drive employing the clamp member  220  and the damping member  280  of  FIG. 6 . Referring to  FIG. 8 , the vibration restriction portion  225  is positioned along an outer edge of the clamp member  220  to face the surface of the disk  150  with the marginal gap “g? defined therebetween. The read/write head  138  is parked between the vibration restriction portion  225  and the surface of the disk  150 . The damping member  280  is coupled to the bottom surface of the vibration restriction portion  225 . When the read/write head  138  collides with the vibration restriction portion  225  due to an impact, the damping member  280  restricts the vibration of the suspension  135  by absorbing an energy of the impact of the read/write head  138  and by reducing a repulsive force applied from the vibration restriction portion  225  to the read/write head  138 . The damping member  280  may be formed of any material having a damping capability to absorb a vibration. For example, the damping member  280  may be formed of a plastic material. Alternatively, other materials that achieve the purposes set forth herein may also be used. For example, the damping member  280  may be made of a viscoelastic material, for example, rubber.  
      The clamp members  220  and the damping member  280  may be prepared or manufactured as independent units from each other, and may be subsequently assembled with each other by fitting the coupling protrusions  285  of the damping member  280  into the coupling holes  228  of the clamp member  220  (see  FIG. 6 ). Alternatively, the damping member  280  may be integrally formed on the clamp member  220  through an injection molding process. When the damping member  280  is attached to the bottom surface of the vibration restriction portion  225  of the clamp member  220 , the damping member  280  absorbs vibration energy of the suspension  135  vertically vibrating between the vibration restriction portion  225  and the disk  150 , thereby quickly attenuating the vibration.  
      Additionally, a damping protrusion  239  may be formed on a front end of the suspension  135 . The damping protrusion  239  may be formed in, for example, a semi-spherical shape. When the suspension  135  vertically vibrates due to the impact, the damping protrusion  239  absorbs the energy of the impact applied to the suspension  135  when the front end of the suspension  135  collides with the vibration restriction portion  225  of the clamp member  220 . As a result, the vibration of the suspension  135  is quickly attenuated to securely protect the read/write head  138  and the data storage disk  150 . The damping protrusion  239  may be formed of any material having a damping capability to absorb the vibration. For example, the damping protrusion  239  may be formed of a plastic material having a flexible property. When the damping protrusion  239  is disposed on the front end of the suspension  135 , the damping protrusion  239  quickly absorbs and attenuates the vibration energy of the suspension  135  vertically vibrating between the clamp member  220  and the data storage disk  150 . Thus, the suspension  135  can be more effectively protected.  
      According to embodiments of the present general inventive concept, since a hard disk drive employs a contact start stop (CSS) type parking system, a size, a weight, and a thickness of the hard disk drive can be reduced, thereby reducing a manufacturing cost of the hard disk drive. Furthermore, since a vibration restriction portion to restrict a vibration of a suspension within a predetermined range is provided on a circumferential outer edge of a clamp member, which clamps a data storage disk to a spindle motor, a physical damage of a read/write head attached to the suspension can be prevented and an anti-impact property is improved.  
      Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.