Abstract:
A clamping device includes a locating cap and a baseboard. The locating cap holds a magnet. The baseboard supports the locating cap. The baseboard includes a holding part and an entrance part. The holding part receives the locating cap. The entrance part is connected to the holding part, and includes a resilient part configured for being pressed by the locating cap to retreat away from a moving path along which the locating cap moves into the holding part, and for restricting the locating cap in the holding part for preventing the locating cap from moving out of the holding part if the locating cap is in the holding part.

Description:
FIELD OF THE INVENTION 
   The present invention generally relates to a clamping device, and more particularly to a clamping device of an optical disc apparatus for clamping an optical disc. 
   DESCRIPTION OF RELATED ART 
   Nowadays, optical discs, such as video compact disc (VCD), digital video/versatile disc (DVD), compact disc-read only memory (CD-ROM) etc, are widely used. Optical disc apparatuses are used for the purpose of recording information to and/or reproducing information from the optical discs. A typical optical disc apparatus generally includes a spindle motor for rotating an optical disc, and a clamping device for clamping the optical disc therein. The clamping device includes a turntable installed on the spindle motor to arrange the optical disc thereon, and a clamper formed above the turntable for clamping the optical disc between the clamper and the turntable. 
   Referring to  FIG. 8 , a clamping device  1  is used for clamping an optical disc (not shown) therein, and a spindle motor (not labeled) is used for rotating the optical disc. The clamping device  999  includes a turntable  7  and a clamper  2 . The turntable  7  is mounted on the spindle motor. The clamper  2  is used for clamping the optical disc on the turntable  7 . The clamper  2  includes a first clamping part  20 , a supporting board  22 , a ring-shaped magnet  24 , and a second clamping part  26 . The first clamping part  20  defines three clasping holes  202  in an imaginary circle thereof. The supporting board  22  defines a guiding hole  222  therein. The second clamping part  26  includes three latches  262  for clasping the first clamping part  20  by passing through the clasping holes  202 . The second clamping part  26  defines a recess portion  264  in a center thereof. The latches  262  are formed around the recess portion  264 . 
   In assembly, the ring-shaped magnet  24  is received in the recess portion  264 . The latches  262  pass through the guiding hole  222 . Each latch  262  is engaged into the corresponding clasping hole  202 , with the ring-shaped magnet  24  being received between the first clamping part  20  and the second clamping part  26 . 
   However, it is difficult for operators to insert each latch  262  to the corresponding clasping hole  202 , so that it is inefficient in mass production. 
   Therefore, a clamping device is needed in the industry to address the aforementioned deficiencies and inadequacies. 
   SUMMARY OF THE INVENTION 
   A clamping device includes a locating cap and a baseboard. The locating cap holds a magnet. The baseboard supports the locating cap. The baseboard includes a holding part and an entrance part. The holding part receives the locating cap. The entrance part is connected to the holding part, and includes a resilient part configured for being pressed by the locating cap to retreat away from a moving path along which the locating cap moves into the holding part, and for restricting the locating cap in the holding part for preventing the locating cap from moving out of the holding part if the locating cap is in the holding part. 
   Other systems, methods, features, and advantages of the present clamping device will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present device, and be protected by the accompanying claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Many aspects of the present clamping device can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
       FIG. 1  is a sectional view of a optical disc apparatus with a clamping device in accordance with an exemplary embodiment, the clamping device including a clamper and a turntable; 
       FIG. 2  is an exploded, isometric view of the clamper of  FIG. 1 , the clamper including a locating cap and a baseboard; 
       FIG. 3  is an exploded, isometric view of the locating cap of  FIG. 2 , viewed from an inverted aspect; 
       FIG. 4  is an assembled, isometric view of the locating cap of  FIG. 3 ; 
       FIG. 5  is an enlarged, isometric view of the baseboard of  FIG. 1 ; 
       FIG. 6  is an assembled, isometric view of the optical disc apparatus of  FIG. 1 , with the turntable removed. 
       FIG. 7  is similar to  FIG. 6 , viewed from an inverted aspect; and 
       FIG. 8  is an exploded, isometric view of a conventional clamping device. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made to the drawings to describe an embodiment of the present clamping device and an embodiment of the present optical disc apparatus. 
   Referring to  FIGS. 1 and 2 , a clamping device  3  of an optical disc apparatus (not labeled) includes a clamper  4  and a turntable  6  for clamping an optical disc  8  therebetween. The clamper  4  includes a baseboard  50 , a locating cap  44  attached to the baseboard  50 , and a magnet  42  received in the locating cap  44 . 
   Referring to  FIG. 3 , the magnet  42  is cylindrical. A guiding hole  421  is defined in the magnet  42  along a longitudinal axis as shown with a dashed line. Two annular surfaces  422  are formed at two opposite sides of the magnet  42 . 
   The locating cap  44  includes a main body  440 , a locating post  450 , and a plurality of L-shaped fasteners  460 . The main body  440  is bowl-shaped, and generally includes a bottom portion  442 , a sidewall  444 , and a rim  446  that is annular. The locating post  450  is formed on a center of the bottom portion  442 , and the fasteners  460  are formed at uniform intervals on the bottom portion  442  around an imaginary circle that has a center point (not shown) on the longitudinal axis. The rim  446  includes a top surface  446   a  parallel to the bottom portion  442  and a side surface  446   b  adjoining the top surface  446   a.    
   The locating post  450  defines a center hole  451  along a longitudinal axis thereof. The locating post  450  includes a cross surface  452  at a top thereof, four alternating convex surfaces  453  and four concave surfaces  454  formed at the sides thereof, and four curved surfaces  455  smoothly connecting the cross surface  452  and the convex surfaces  453 . A distance between two opposite convex surfaces  453  is greater than a diameter of the guiding hole  421  of the magnet  42 . 
   Each fastener  460  includes two ends (not labeled). One end is integrally formed on the bottom portion  442 . The other end is a hook end, and includes a fastening surface  461  facing the bottom portion  442 , and a sliding slope  462  deviating from the fastening surface  461 . 
   Referring to  FIGS. 5 ,  6 , and  7 , the baseboard  50  includes a holding part  510  where the locating cap  44  is held, and an entrance part  520  adjoining the holding part  510 . The holding part  510  of the baseboard  50  includes a frame  512  with an opening  514  for receiving the locating cap  44 . The frame  512  is a circular arc, and includes a sidewall  511  substantially surrounding the opening  514  and a plurality of first blocks  513  and second blocks  515  extending from the sidewall  511  toward the opening  514 . The first blocks  513  and the second blocks  515  correspondingly locate on two parallel imaginary planes (not shown). 
   The entrance part  520  includes a pre-supporting platform  540  for pre-supporting the locating cap  44 , and a resilient part  530  between the pre-supporting platform  540  and the holding part  510 . The resilient part  530  is yieldable from a moving path  550  where the locating cap  44  moves into the opening  514 . When the locating cap  44  moves towards the holding part, the resilient part  530  is pressed and bent to give way to the locating cap  44 . When the locating cap  44  is in the holding part  510 , the resilient part  530  prevents the locating cap  44  from moving out of the opening  514 . 
   The pre-supporting platform  540  has a semi-circular segment shape, and includes a plate  542  and a flange  544  bounding the plate  542 . The flange  544  has two ends  538  located between the entrance part  520  and the holding part  510 . The resilient part  530  includes a resilient board  532  attached to the plate  542 , and two resilient clips  534  each correspondingly extending from the two ends  538 . The pre-supporting platform  540  also defines a gap  539  abutting each resilient clip  534 . A minimum distance between the resilient clips  534  is smaller than a maximal diameter of the locating cap  44 . 
   The resilient board  532  includes a first side  531  formed firmly on the plate  542 , a second side  533  extending into the opening  514 . Three parallel protrusions  535  are formed on the resilient board  532 . Each protrusion  535  has a first slope  536  facing the flange  544 , with the first slope  536  being deflectable away from the moving path  550  of the locating cap  44 . Each resilient clip  534  has a second slope  537  thereon. The second slopes  537  of the resilient clips  534  are deflectable away from the moving path  550 . 
   Referring to  FIG. 4 , in an assembly of the magnet  42  and the locating cap  44 , the magnet  42  is to be installed into the locating cap  44 . The sliding slope  462  of each fastener  460  is pressed by the magnet  42  to deflect outwards, while the locating post  450  is pressed by the magnet  42  to contract inwards. Therefore, the fasteners  460  give way to the magnet  42 , and the locating post  450  passes through the guiding hole  421  of the magnet  42 . After assembly, the fasteners  460  are restored under restoration forces, and the fastening surfaces  461  abut on one of the annular surfaces  222 . The magnet  42  is firmly fastened in the locating cap  44  by a restoration force of the locating post  450 . 
   Referring to  FIGS. 2 and 5 , in an assembling of the locating cap  44  and the baseboard  50 , the locating cap  44  is pre-supported on the plate  542 . When the locating cap  44  is moved into the holding part  510 , the first slope  536  is pressed by the locating cap  44  to yield away from the moving path  550 . I.e., the second side  533  rotates around the first side  531  to deflect away from the moving path  550 . The second slopes  537  are also pressed by the locating cap  44  with the resilient clip retreating into the gap  539 . When the first slope  536  and the second slopes  537  are pressed in the direction parallel to the moving path  550 , the locating cap  44  moves into the opening  514  without any obstacles. That is, the resilient board  532  and the resilient clips  534  are pressed to give way to the locating cap  44  during assembly. 
   After the assembling, referring to  FIGS. 1 ,  5 ,  6  and  7 , the locating cap  44  is in the opening  514  with the resilient board  532  and the resilient clip  534  restricting the locating cap  44  in the holding part  510 . The first blocks  513  and the second blocks  515  prevent the locating cap  44  from moving out of the opening  514  in a direction perpendicular to the disc. 
   It is very convenient for operators to assemble the locating cap  44  into the baseboard  50 . Thus, the clamping device  3  design is superior when mass producing. 
   It should be emphasized that the above-described preferred embodiments, are merely possible examples of implementation of the principles of the invention, and are merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiments of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and be protected by the following claims.