Abstract:
A self-compensating balancer for a disk player is provided and includes a supporting plate fixed to a rotating shaft of a spindle motor for supplying rotary power to a disk. Pivot pins are installed in the supporting plate and two or more pendulums are arranged around the supporting plate. The pivot pins and pendulums are linked by connectors, such that upon rotation of the shaft, the connectors are elastically transformed and a centroid of the pendulums faces a centroid of the disk, centered around the rotating shaft of the spindle motor, due to a centrifugal force.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to disk players and, more particularly, to a self-compensating balancer for a disk player that is capable of preventing internal vibrations caused by eccentric center of mass of a disk and a turntable combined therewith. 
     2. Description of the Related Art 
     In general, disk players, for recording information on recording media such as compact disks (CDs), CD-ROMs, digital versatile disks (DVDs) and for reproducing recorded information from the recording media, must protect the disks and optical pickups from external shock and internal vibration. 
     In general, as shown in FIG. 1, a disk player includes a vertically rotatable deck base  10  hinged to a housing, a deck plate  20  combined with the deck base  10 , a spindle motor  21  installed on the deck plate  20  for providing rotary power to a disk  1 , and a turntable  23  combined with a rotating shaft  22  of the spindle motor  21 , on which the disk  1  is loaded. Also included are a damper  40  and an optical pickup  25 , which are installed on the upper internal surface of the housing so as to face the turntable  23 . Here, the damper  40  clamps the disk  1  to the turntable  23 . The optical pickup  25  is combined with the deck plate  20  so that the optical pickup  25  can be transferred in the radial direction of the disk  1 , during recording and reproducing operations. 
     A damper  30  is installed between the deck base  10  and the deck plate  20 . The damper  30  absorbs external vibrations directly transmitted to the deck plate  20 , the spindle motor  21 , and the optical pick-up  25 , through the deck base  10 . The damper  30  is formed of a material such as soft rubber or polyurethane. 
     The disk player having the above structure can effectively protect the disk  1  and the optical pick-up  25  from an external shock. However, a method of easing the internal vibration caused by the eccentric mass of the disk  1  during the rotation of the spindle motor  21  has not been considered. The disk  1  has an eccentric center of mass caused by a discordance between the center of gyration of the disk  1  and the centroid of the disk  1  caused by errors in the manufacturing processes thereof. The rotating shaft  22  of the spindle motor  21  revolves due to the eccentric mass of the disk  1 , during the rotation of the disk  1 . The influence of the revolution of the rotating shaft  22  does not have a significant effect in a low-speed model such as 1× and 2×speed models. However, the eccentric rotation does make it difficult to record information on and reproduce information from the recording media in a high-speed model such as a 6× or 8×speed model. 
     SUMMARY OF THE INVENTION 
     In order to solve the above problems, it is an object of the present invention to provide a self-compensating balancer for a disk player and a turntable combined with the same, which are capable of preventing internal vibrations caused by an eccentric mass of a disk during high-speed rotation. 
     To achieve the above object, there is provided a self-compensating balancer for a disk player, comprising a supporting plate fixed to a shaft rotated by a spindle motor for supporting rotary power to a disk, pivot pins installed in the supporting plate, two or more pendulums arranged around the supporting plate, and connectors for connecting the pendulums to the pivot pins. The connectors are operative to be elastically transformed so that the centroid of the pendulums faces the centroid of the disk, centered around the rotating shaft of the spindle motor, due to a centrifugal force, during the rotation of the disk. 
     The connectors are preferably thin strings that can be bent by an external force. 
     One or more connectors are preferably formed of nylon resin that can be bent by the external force. 
     To achieve the above object, there is provided a turntable combined with a self-compensating balancer for a disk player, comprising a seating unit, having a protrusion to which the central hole of a disk is combined and rotated in combination with the rotating shaft of a motor. A supporting plate is fixed to the rotating shaft so as to be separated from the seating unit by a predetermined distance and a plurality of pendulums are interposed between the seating unit and the supporting plate, such that the pendulums do not interfere with each other. A plurality of pivot pins are installed between the seating unit and the supporting plate. Connectors are provided for connecting the pivot pins to the pendulums. The connectors are capable of being elastically transformed so that a centroid of the pendulums faces a centroid of the disk centering around the rotating shaft during the rotation of the disk and, thus, the internal vibration caused by the eccentric mass of the disk is prevented. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above object and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings, in which: 
     FIG. 1 is a schematic exploded perspective view showing a conventional disk player; 
     FIG. 2 is a schematic sectional view showing a self-compensating balancer and a turntable combined with the self-compensating balancer according to an embodiment of the present invention; 
     FIG. 3 is a partial sectional view taken along the line III—III of FIG. 2; and 
     FIGS. 4 and 5 are schematic partial sectional views showing other embodiments of the connector shown in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 2, a spindle motor  41  for rotating a disk  1  is supported by a deck plate  40  installed in the housing of a disk player. A turntable combined with a self-compensating balancer according to an embodiment of the present invention is installed with a rotating shaft  41   a  of the spindle motor  41 . The turntable supports the disk  1  and prevents vibration and noise caused by an eccentric mass of the disk  1 . 
     The turntable combined with the self-compensating balancer includes a first supporting plate  42  and a second supporting plate  43  fixed to the rotating shaft  41   a . A plurality of pendulums  44  are interposed between the first  42  and second  43  supporting plates. A plurality of pivot pins  45  are inserted between the first  42  and second  43  supporting plates. A plurality of connectors  46  respectively join the plurality of pendulums  44  to the plurality of pivot pins  45 . 
     The first  42  and second  43  supporting plates are installed in parallel and are separated from each other by a predetermined distance in a direction vertical to the axial direction X of the rotating shaft  41   a . The first supporting plate  42  forms a seating unit having a seating surface  42   a  for seating the disk  1 . A protrusion  42   b  protrudes above a center of the first supporting plate  42  so as to be combined with a central hole  1   a  of the disk  1 . The first supporting plate  42  is rotated together with the second supporting plate  43  by driving the spindle motor  41 , in a state in which the first supporting plate  42  supports the disk  1 . Also, the first  42  and second  43  supporting plates are connected to each other by the pivot pins  45 . The pivot pins  45  are for supporting the motion of the pendulums  44  and are installed around the rotating shaft  41   a  so that they are parallel to the axial direction x of the rotating shaft  41   a.    
     The plurality of pendulums  44  are installed between the first  42  and second  43  supporting plates. The pendulums  44  are preferably in the form of plates, as shown in FIG.  3 . The pendulums  44  in the form of plates are positioned to be parallel to the first  42  and second  43  supporting plates. Accordingly, it is possible to prevent the pendulums  44  from interfering with each other. Also, the pendulums  44  are separated from each other so as not to interfere with each other. An end of each of the pendulums  44  is respectively connected to each of the pivot pins  45  by the connectors  46 . 
     The connectors  46  preferably comprise string that can be bent even by a very small external force. Therefore, a plurality of strings are connected to the pivot pins  45  and the pendulums  44 . Also, the string is preferably formed of thin iron that has a low stiffness and which is not easy to cut, so as to be bent even by the small eccentric mass of the disk  1 . 
     As shown in FIG. 4, the pivot pins  45  and the pendulums  44  can be connected by a plurality of connectors  46 ′ formed of synthetic resin such as nylon. In this case, the connectors  46 ′ can be formed by an injection molding process using the synthetic resin, which has a low stiffness. The connectors  46 ′ are respectively connected to the pendulums  44  and the pivot pins  45  by bonding or clamping. 
     In a further embodiment, as shown in FIG. 5, the pivot pin  45  and the pendulum  44  are connected to each other by a connector  46 ″, which is formed of nylon and has a similar thickness as that of the pendulum  44 . In this case, the connector  46 ″ is elastically transformed so that the pendulum  44  minutely rotates by a small force centered around the pivot pin  45 ; that is, a pendulum motion can be obtained. 
     In the device having the above structure, when the number of rotations of the disk  1  is larger than the natural frequency of the disk  1  and when the disk actually rotates at normal speed, the pendulum  44  moves to a position where the eccentric mass of the disk  1  is compensated for when the connectors  46  are elastically transformed due to a centrifugal force. Thus, according to the invention, the pendulum  44  is disposed in such a position that compensation is made for the eccentric mass of the disk  1 . Namely, on the basis of the rotating shaft  41   a , the resonance center of the disk  1  and the position of the eccentric mass of the disk  1  are on the same side and the centroid of the self-compensating balancer, that is, the position of the compensating mass is on the side opposite to the oscillation center of the disk and the position of the eccentric mass of the disk  1 , due to the centrifugal force. Therefore, non-equilibrium with respect to the eccentric mass of the disk  1  is offset. Accordingly, the oscillation radius of the rotating shaft  41   a  is significantly reduced. Also, the internal exciting force of the deck plate  40  with respect to the eccentric mass of the disk  1  is relaxed. In particular, according to the present invention, a frictional force does not exist between the pendulums  44 , the pivot pins  45  and the elastically transformed connectors  46 . Accordingly, the pendulums  44  can be appropriately moved. Therefore, since the eccentric mass of the disk  1  is minute, it is possible to prevent even vibrations caused by a minute eccentric mass of the disk  1  although the centrifugal force applied to the pendulums  44  is weak. 
     The self-compensating balancer for the disk player according to the present invention and the turntable combined with the same have simple structures that can simultaneously perform the function of balancing the eccentric mass of the disk and the function of supporting and rotating the disk. 
     Also, the pendulums can easily move without being affected by friction caused by the rotation of the pivot pins, by connecting the pendulums to the pivot pins by the connectors that can be elastically transformed. Therefore, the pendulums are easily moved to positions where the eccentric mass is compensated for by the minute force caused by the eccentric mass of the disk. Accordingly, it is possible to effectively prevent the internal vibration. 
     Also, it is possible to drive a disk player at a high speed of 6× speed or greater by using the self-compensating balancer and the turntable according to the present invention for the disk player. 
     It is contemplated that numerous modifications may be made to the apparatus of the present invention without departing from the spirit and scope of the invention as defined in the claims.