Abstract:
A disk clamping apparatus of a spindle motor and a spindle motor having the same are disclosed, wherein the apparatus includes a case inserted into an inner periphery of a disk for integrally rotating with a rotation shaft coupled with a rotor yoke, a plurality of claws each formed at a predetermined gap in the case, an arm mounted between the claws in the case and having a body with a slanted surface and slantedly formed at an upper surface of the disk, guide rails each mounted at both lateral surfaces of the body and a disengagement prevention rails each mounted at each guide rail and curvedly formed at the bottom surface for contacting the rotor yoke, and an elastic member elastically supporting the body by being interposed between the body and the case.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit under 35 U.S.C. §119 of Korean Application Number 10-2009-0024433, filed Mar. 23, 2009, which is hereby incorporated by reference in its entirety. 
       BACKGROUND 
       [0002]    The present disclosure relates to an apparatus for clamping disk of spindle motor and a spindle motor having the same. 
         [0003]    In general, a spindle motor performs the function of rotating a disk at a high speed to enable an optical pickup which linearly reciprocates in an optical disk drive (ODD) to read data recorded on the disk. 
         [0004]    A spindle motor includes a stator, a rotation shaft rotating relative to the stator, a rotor fixed to the rotation shaft and including a rotor yoke, and a disk clamping apparatus rotating with the rotation shaft and fixing the disk. 
         [0005]    The disk clamping apparatus fixing the disk includes a disk-shaped case, a plurality of claws formed at a lateral surface of the case to contact an inner periphery of the disk and to support the disk so that a disk center can correspond with the center of the rotation shaft, an arm contacting an inner periphery upper end corner of the disk to inhibit the disk from disengaging from the case, and an elastic member mounted inside the case to elastically support the arm. 
         [0006]    The conventional arm of the spindle motor is discrete from an upper surface of the rotor yoke such that the disk pushes up the arm when the arm and the disk are coupled. As a result, the arm suffers from a disadvantage in that a coupling force between the arm and the disk greatly decreases to cause the disk to disengage from the disk clamping apparatus even at a small shock. 
       BRIEF SUMMARY 
       [0007]    The present disclosure is to provide an apparatus for clamping disk (hereinafter called a disk clamping apparatus) of a spindle motor configured to improve a coupling structure between an arm and a disk to inhibit the disk from easily disengage from the arm. 
         [0008]    The present disclosure is also to provide a spindle motor having a disk clamping apparatus of a spindle motor. 
         [0009]    According to one aspect of the present disclosure, the object described above may be achieved by a disk clamping apparatus of a spindle motor which comprises: a case inserted into an inner periphery of a disk for integrally rotating with a rotation shaft coupled with a rotor yoke; a plurality of claws each formed at a predetermined gap in the case; an arm mounted between the claws in the case and having a body with a slanted surface and slantedly formed at an upper surface of the disk, guide rails each mounted at both lateral surfaces of the body and a disengagement prevention rails each mounted at each guide rail and curvedly formed at the bottom surface for contacting the rotor yoke; and an elastic member elastically supporting the body by being interposed between the body and the case. 
         [0010]    According to another aspect of the present invention, the object described above may be achieved by a spindle motor which comprises: a stator; a rotor having a rotation shaft rotating relative to the stator and a rotor yoke coupled to the rotation shaft; a felt mounted at an upper surface of the rotor yoke to inhibit the disk from slipping; an arm having a case fixed to the rotor and inserted into an inner periphery of the disk, a plurality of claws formed at the case, a body mounted between the case and the plurality of claws and formed with a slanted surface relative to an upper surface of the disk, and a disengagement prevention rail mounted at the body to contact the rotor yoke and to inhibit the body from being lifted by the disk; and a disk clamping apparatus interposed between the body and the case to elastically support the body. 
         [0011]    According to still another aspect of the present invention, the object described above may be achieved by a spindle motor which comprises: a rotatably mounted rotation shaft; a rotor having a rotor yoke coupled to the rotation shaft to integrally rotate with the rotation shaft and mounted with a disk; a felt, one surface of which being coupled to the rotor yoke and the other surface of which being contacted by the disk, for preventing the disk from slipping; a case, one surface of which being coupled to the rotor and a lateral surface of which being inserted by the disk; a plurality of anus linearly and rotatably mounted inside the case to enter and leave a lateral surface of the case and to inhibit the disk from being disengaged by being hitched at one distal end thereof by an inner peripheral corner of the disk; and a disk clamping apparatus having an elastic member elastically supporting the arm from a lateral outer surface of the case, wherein A/B is 1.08˜1.18, where A is a height of the arm at a rotational direction, and B is a height of the arm at a rotational direction from the other surface of the felt to a surface of the case. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0012]      FIG. 1  is a cross-sectional view of a spindle motor according to an exemplary embodiment of the present invention. 
           [0013]      FIG. 2  is a partially exploded perspective view of a disk clamping apparatus of  FIG. 1 . 
           [0014]      FIG. 3  is an enlarged view of an arm of  FIG. 2 . 
           [0015]      FIGS. 4 and 5  are cross-sectional views along line “P-P” of  FIG. 3  in which the disk clamping apparatus is coupled to the rotor yoke. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    An apparatus for clamping disk of spindle motor and a spindle motor having the same will be described in detail with reference to the accompanying drawings. 
         [0017]      FIG. 1  is a cross-sectional view of a disk clamping apparatus and a spindle motor having the same according to an exemplary embodiment of the present invention. 
         [0018]    Referring to  FIG. 1 , a bearing housing  120  is perpendicularly arranged on the base  110 . 
         [0019]    In designating a direction and a surface of constituent parts, a direction and a surface facing an upper vertical side of the base  110  are respectively called “an upper side” and “an upper surface”, while a direction and a surface facing a bottom vertical side of the base  110  are respectively called “a bottom side” and “a bottom surface”. 
         [0020]    The cylindrical bearing housing  120  with upper and bottom surfaces opened and the bottom surface being coupled to the base  110  is provided. 
         [0021]    The bearing housing  120  is coupled at a bottom surface to a thrust stopper  131 , and the bottom surface of the bearing housing  120  is blocked by the thrust stopper  131 . A bearing  140  is press-fit into the bearing housing  120  and the bearing  140  is rotatably installed with a rotor. 
         [0022]    The periphery of the bearing housing  120  is mounted with a stator, and the stator may include a core  161  and a coil  163 . The core  161  is fixed to the periphery of the bearing housing  120  and the core  61  is wound on the coil  163 . 
         [0023]    The rotor may include a rotation shaft  151  rotatably mounted in the bearing  140 , a bottom-opened cylindrical rotor yoke  153  to be coupled to an upper periphery of the rotation shaft  151 , and a magnet  155  coupled to an inner circumferential surface of the rotor yoke  153 . The magnet  155  faces the core  161  of the stator. 
         [0024]    In a case a current flows in the coil  163 , the rotation shaft  151  is rotated by the electromagnetic force generated between the coil  163  and the magnet  155 . In order to secure a strong coupling between the rotation shaft  151  and the rotor yoke  153 , a coupling pipe  153   a  is protrusively formed at a center of the rotor yoke  15 , and the coupling pipe  153   a  is coupled to the rotation shaft  151  via a bushing  157 . 
         [0025]    An upper edge of the rotor yoke  153  is mounted with a felt  159  for preventing a disk  50  from slipping relative to the rotor yoke  153  by being contacted with the disk  50 . A bottom surface of the felt  159  is coupled to an upper surface of the rotor yoke  153 , and the upper surface of the felt  159  is brought into contact with a bottom surface of the disk  50 . 
         [0026]    The rotor yoke  153  is formed with a stopper  171  hitching at an upper peripheral surface of the bearing housing  120  to inhibit the rotor from being disengaged from the bearing housing  120 . The periphery of the bearing housing  120  is formed with a suction magnet  175  for preventing the rotor from lifting upwards of the bearing housing  120  when the rotor is rotated. The suction magnet  175  may be coupled to the rotor yoke  153 . 
         [0027]    The unexplained reference numeral  135  in  FIG. 1  is a thrust plate configured to inhibit the thrust stopper  131  from being worn and torn. 
         [0028]    The coupling pipe  153   a  of the rotor yoke  153  is coupled to a disk clamping apparatus  200  which in turn supports the disk  50  mounted on the rotor yoke  153 . 
         [0029]    Now, the disk clamping apparatus  200  will be described in detail with reference to  FIGS. 2 and 3 . 
         [0030]      FIG. 2  is a partially exploded perspective view of a disk clamping apparatus of  FIG. 1 , and  FIG. 3  is an enlarged view of an arm of  FIG. 2 . 
         [0031]    Referring to  FIGS. 2 and 3 , the disk clamping apparatus  200  may include a case  210 , claws  220 , an arm  230  and an elastic member  240 . 
         [0032]    The case  210  is provided with a bottom-opened cylindrical shape. An upper central surface of the case  210  is formed with a coupling hole  211  into which the coupling pipe  153   a  of the rotor yoke  153  is insertedly coupled. 
         [0033]    The disk  50  is inserted into a lateral surface of the case  210 , and the opened bottom of the case  210  faces an upper surface of the rotor yoke  153 . In order to secure a stable mounting, the bottom of the case  210  is brought into contact with an upper surface of the rotor yoke  153 . 
         [0034]    The claw  220  comes in a plurality and integrally formed with the lateral surface of the case  210 . Each of the plurality of claws  220  is formed at an identical space at the case  210 . The claw  220  is shaped of a cantilever to fix an inner surface of the disk  50 . 
         [0035]    The claws  220 , for example, are radially formed based on the center of the case  210  and are brought into contact with an inner surface of the disk  50  inserted into the case  210  to support the disk  50  so that the center of the disk  50  corresponds with the center of the rotation shaft  151 . 
         [0036]    The lateral surface of the case  210  is radially formed with a plurality of first entry holes  213  based on the center of the case  210 , and a plurality of second entry holes each connected to the first entry hole  213  and having a larger size than that of the first entry hole  213 . 
         [0037]    The first entry hole  213  is formed between the claws  220 , and an arm  230  (described later) performs the linear and reciprocal movements inside the first and second entry holes  213 ,  215 . 
         [0038]    The arm  230  may include a body  231 , guide rails  233  and a disengagement prevention rail  235  and be mounted inside the case  210 . One side of the body  231  is located at an outer lateral surface of the case  210 , and the other side of the body  231  is mounted inside the case  210  to enter and leave the first entry hole  213 . 
         [0039]    One lateral surface facing the disk  50  in the body  231  mounted an a periphery of the case  210  includes an inclination formed at a slanted form resembling the center of the case as it faces towards the rotor yoke  153 . In the present embodiment, the inclination is reversely formed relative to the upper surface of the disk  50 . 
         [0040]    In a case the disk  50  enters the case  210 , an inner surface of the disk  50  is brought into contact with an upper end of the body  231  of the arm  230 , whereby the body  231  is rotated clockwise and is pushed inside the case  210 . 
         [0041]    In a case the disk  50  is completely inserted into the lateral surface of the case  210  to be mounted on the rotor yoke  153 , the body of the arm  230  returns to its original shape by the elastic member  240 , whereby an inner upper corner of the disk  50  is hitched at the inclination of the body  231  to inhibit the disk  50  from being disengaged towards the case  210 . 
         [0042]    Each of the guide rails  233  is formed at a lateral surface of the body  231  to enter or leave the second entry hole  215 . The guide rails  233  and the second entry hole  215  guide to facilitate the smooth linear movement of the arm  230 . 
         [0043]    The disengagement prevention rail  235  is extensively formed from each of the guide rails  233  to be positioned inside the case  210  as the body  231  of the arm  230  moves linearly. The bottom surface of the disengagement prevention rail  235  is brought into contact with the lateral surface of the case  210  to inhibit the arm  230  from disengaging towards the external lateral surface of the case  210  when the body  231  of the arm  230  moves towards the external side of the case  210 . 
         [0044]    Because the disengagement prevention rail  235  is protruded from a rear surface facing the inclination of the body  231  to contact the rotor yoke  153 , a part of the body  231  is inhibited from being lifted by the disk  50  after the disk  50  is coupled to the inclined surface of the body  231 . 
         [0045]    An upper surface of the body  231  at the arm  230  and an upper surface of the case are arranged in parallel while the disk  50  is fixed at the body  231  of the arm  230  by the disengagement prevention rail  235 . 
         [0046]    In the present embodiment, the body  231 , the guide rail  233  and the disengagement prevention rail  235  are integrally moved. 
         [0047]    The elastic member  240  disposed inside the case  210  elastically supports the arm  230  from the lateral external surface of the case  210  in order for the arm  230  to securely support the disk  50 . At this time, one side and the other side of the elastic member  240  are respectively formed with support protruders  217  (see  FIG. 4 ) to face the other end of the body  231  and the case  210 . 
         [0048]    The disk clamping apparatus  200  according to the present exemplary embodiment can securely support the disk  50  and reduce an installation space as well, the detailed description of which will be provided with reference to  FIGS. 4 and 5 . 
         [0049]      FIGS. 4 and 5  are cross-sectional views along line “P-P” of  FIG. 3  in which the disk clamping apparatus is coupled to the rotor yoke. 
         [0050]    Referring to  FIGS. 4 and 5 , assuming that A is a height of the arm  230  from bottom to top, and B is a height from an upper surface of a felt  159  to an upper surface of the case  210 , A/B is 1.08˜1.18. 
         [0051]    In the present embodiment, the height of the arm  230  from the bottom to the top is substantially the same as that from the bottom of the disengagement prevention rail  235  to the upper of the body  231 . 
         [0052]    The meaning of “A/B is 1.08˜1.18” is that the height of the arm is not relatively much lower than the height of the case  210 , such that in a case the disk clamping apparatus  200  is coupled to the rotor yoke  153 , the bottom surface of the arm  230  disposed inside the case  210  is brought into contact with the upper surface of the rotor yoke. As a result, in a case the disk  50  is mounted on the rotor yoke  153  to support the arm  230 , the body  231  of the arm  230  contacting the inner upper corner of the disk  50  is hardly lifted by the disk  50 , as illustrated in  FIG. 5 . 
         [0053]    The following Table 1 shows a measurement result of a support force of the disk  50  inserted into the disk clamping apparatus  200  of the spindle motor according to the present embodiment thus configured and a disengagement distance. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Support force 
                 Disengagement 
               
               
                 A/B 
                 (g f ) 
                 distance (mm) 
               
               
                   
               
             
             
               
                 1.04 
                 160 
                 2.26 
               
               
                 1.05 
                 180 
                 2.25 
               
               
                 1.07 
                 180 
                 2.23 
               
               
                 1.08 
                 200 
                 2.20 
               
               
                 1.09 
                 200 
                 2.20 
               
               
                 1.10 
                 200 
                 2.17 
               
               
                 1.16 
                 200 
                 2.17 
               
               
                 1.17 
                 210 
                 2.16 
               
               
                 1.18 
                 210 
                 2.17 
               
               
                 1.19 
                 Motion interference 
               
               
                   
                 generated 
               
               
                 1.20 
                 Motion interference 
               
               
                   
                 generated 
               
               
                 1.21 
                 Motion interference 
               
               
                   
                 generated 
               
               
                   
               
               
                 [A is a height of an arm in the direction of rotational axis] 
               
               
                 [B is a height in the direction of rotational axis from an upper surface of a felt to an upper surface of the case] 
               
             
          
         
       
     
         [0054]    The measurement result of the above Table &lt;1&gt; is an average value of support forces and disengagement distances of 10 spindle motors according to the present disclosure where A/B is 1.04˜1.21. 
         [0055]    As shown in Table &lt;1&gt;, in a case where A/B is 1.041.07, the support force and the disengagement distance of disk  50  are 160˜180 g f  and 2.23˜2.26 mm respectively, where it could be noted that the support force is relatively weak, while the disengagement distance is relatively long. 
         [0056]    In a case where A/B is 1.08˜1.18, the support force and the disengagement distance of disk  50  are 200˜210 g f  and 2.16˜2.20 mm respective, where it could be noted that the support force is relatively strong while the disengagement distance is relatively short. Furthermore, in a case where A/B is equal to or greater than 1.19, motion interference from the arm  230  can be noticed. 
         [0057]    Therefore, A/B may be 1.08˜1.18, and more preferably A/B may be 1.16˜1.18 and an optimal A/B may be 1.10. 
         [0058]    In the present exemplary embodiment, a bottom surface of the disengagement prevention rail  235  of the arm  230  oppositely contacting the upper surface of the rotor yoke  153  is formed with a curvature  235   a  protrusively formed towards the rotor yoke  153 . 
         [0059]    In the present exemplary embodiment, the bottom surface of the disengagement rail  125  and the rotor yoke  153  may be mutually line-contacted. Alternatively, the bottom surface of the disengagement prevention rail  235  may be a spherical surface protruding toward the rotor yoke  153 , where the disengagement rail  125  and the rotor yoke  153  may be mutually line-contacted. 
         [0060]    At this time, in a case a radius of curvature at a curvaceous surface  235   a  of the disengagement prevention rail  235  at the arm  230  is defined as R, a radius of curvature of the disengagement prevention rail  235  may be 3 mm≦R≦7 mm. 
         [0061]    A measurement result of the support force of the disk  50  measured by changing the radius of curvature at the curvaceous surface  235   a  of the disengagement prevention rail  235  at the arm  230  is provide in the following Table 2, in a case where the A/B is fixed at 1.10. 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Radius of curvature 
                 Support force 
                   
               
               
                   
                 (mm) 
                 (gf) 
                 remarks 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10 
                 180 
                 Motion interference 
               
               
                   
                   
                   
                 generated 
               
               
                   
                 9 
                 180 
                 Motion interference 
               
               
                   
                   
                   
                 generated 
               
               
                   
                 8 
                 200 
                 Motion interference 
               
               
                   
                   
                   
                 generated 
               
               
                   
                 7 
                 200 
                 — 
               
               
                   
                 6 
                 200 
                 — 
               
               
                   
                 5 
                 200 
                 — 
               
               
                   
                 4 
                 200 
                 — 
               
               
                   
                 3 
                 200 
                 — 
               
               
                   
                 2 
                 180 
                 — 
               
               
                   
                 1 
                 170 
                 — 
               
               
                   
                   
               
             
          
         
       
     
         [0062]    The measurement result of the above Table &lt;2&gt; is an average value measured from 10 spindle motors each having a different radius of curvature according to the present exemplary embodiment. 
         [0063]    As depicted in Table &lt;2&gt;, in a case the radius of curvature is 1˜2 mm, the support force is 170˜180 g f , which is relatively weak, in a case where the radius of curvature is 3˜7 mm, the support force is 200 g 1 , which is relatively strong, and in a case where the radius of curvature is equal to or greater than 5 mm, motion interference from the arm  230  can be noticed. Therefore, the radius of curvature R of the disengagement prevention rail  235  is preferably in the range of 3 mm≦R≦7 mm. 
         [0064]    Any reference in this specification to “one embodiment,” “an embodiment,” “exemplary embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to affect such feature, structure, or characteristic in connection with others of the embodiments. 
         [0065]    Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawing and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.