Abstract:
There is provided an optical pickup actuator for actuating a lens holder having an object lens according to an interaction between coils and magnets. The optical pickup actuator includes a lens-seating portion formed on the lens holder to support the object lens and a lens guide portion protruding from the lens-seating portion to securely support the object lens. The lens guide portion has an adhesive confining groove in which adhesive can be injected to securely fix the object lens.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an optical pickup actuator for reading and writing data from and to an optical recording medium. 
     2. Description of the Related Art 
     The optical pickup actuator maintains a relative location between an object lens and an optical recording medium at a predetermined distance by moving a moving part on which the object lens is mounted and reads and writes information from and to the optical recording medium by following a track of the optical recording medium. 
     The optical pickup actuator has a permanent magnet and a coil. When the electric current is applied to the coil, the optical pickup actuator moves the object lens to a desired location. At this point, the moving part moves in focusing and tracking directions that are perpendicular to each other. 
       FIGS. 1A and 1B  are schematic views of an optical pickup actuator according to the related art. 
     Referring to  FIGS. 1A and 1B , an optical pickup actuator includes a lens holder  102  for mounting an object lens on a central portion thereof and having an outer circumference around which tracking and focusing coils  106  and  105  are wound, magnets and yokes  103  and  104  installed on the base and opposing the tracking and focusing coils  106  and  105  of the lens holder  102 , a plurality of wire suspensions  107  each having a first end fixed on a side surface of the lens holder to support the lens holder  102 , and a damper holder  109  to which a second end of each wire suspensions  107  is fixed. 
     Reference numeral  109  denotes fixing plates fixed on the lens holder  102  and the first ends of the wire suspensions  107  are fixed on the fixing plates  109  through a soldering process. 
     The optical pickup actuator will be now described in more detail. 
     The object lens  101  is mounted on the central portion of the lens holder  102 . The focusing coil  105  for focusing is wound around each corner of the lens holder. The tracking coil for tracking is wound around a center portion of left and right surfaces of the lens holder  102 . 
     The yokes  104  are formed of a ferromagnetism material protrude. The yokes face the focusing and tracking coils  105  and  106 . The magnets are fixed on front surfaces of the respective yokes  104 . The yokes  104  are fixed on a pickup base (not shown). 
     The fixing plates  108  are couple to the lens holder  102 . The first ends of a pair of wire suspensions  107  parallel to each other are fixed to each fixing plate  108  through the soldering process. The second ends of the wire suspensions are fixedly inserted in a damper of the damper holder  109 . 
     The damper is coupled inside the damper holder  109  so that the wire suspensions each having a rigidity can has a damping property. A main board (not shown) is coupled to an outer surface of the damper holder  109 . The second ends of the wire suspensions  107  are actually fixed on the main board. 
     The lens holder  102  is lifted by the wire suspensions  107  and electric current is applied to the wire suspensions  107 . 
     When electric current is applied to the tracking coil  106 , repulsive and attractive forces are generated by an electromagnetic force between the focusing coil  105  and the magnets  103 . By the repulsive and attractive forces, the lens holder  102  moves in the focusing direction (in a vertical direction), thereby operating a focusing servo for compensating for a focusing error. 
     The above-described optical pickup actuator is a moving coil type where the focusing and tracking coils  105  and  106  move together with the lens holder  102  around which the focusing and tracking coils  105  and  16  are wound. 
     There is also a moving magnet type where the magnets are attached on the outer circumference of the lens holder so as to move together with the lens holder. At this point, the movement using the magnets and the coils uses Lorentz&#39;s force of Fleming&#39;s left-hand rule. 
     The above-described optical pickup actuator reads and writes information on an optical recording medium. In recent years, as multimedia systems have been rapidly developed and capacities of multimedia contents such as games and movies has been increased, it has been required that the optical pickup actuator must be reliable to stably drive the multimedia systems for many hours. 
     When the multimedia system is driven for many hours, heat is generated by the electric current applied to the coils of the optical pickup actuator and transmitted to the object lens through the lens holder. 
     When the heat generated by the coils is transmitted to the object lens for a long time, the aberration is increased. Furthermore, when excessive electric current is applied to the coils, the object lens may be cracked due to a thermal-stress. Therefore, there is a need for an optical pickup actuator that can improve a driving reliability by reducing the heat transmitted from the coils to the object lens. 
     Also, in a high speed optical pickup actuator, even when the object lens is attached to the lens holder using adhesive, the lens holder may be different in a frequency response from the object lens since the adhesive force is not enough. That is, a resonance peak of the lens holder may be greater than a resonance peak of the object lens. 
     Therefore, there is also a need for an optical pickup actuator that can improve the driving reliability by attenuating the resonance characteristics. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to an optical lens actuator that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     An object of the present invention is to provide an optical pickup actuator that can minimize the transmission of heat from coils to an object lens by forming recessed portions on side surfaces of a lens holder. 
     Another object of the present invention is to provide an optical pickup actuator that can block out heat that is transmitted from coils to an object lens by processing heat discharge grooves on a lens-seating portion surrounding a beam-passing hole. 
     Still another object of the present invention is to provide an optical pickup actuator that can enhance a bonding force of an object lens by improving a bonding structure between a lens holder and the object lens. 
     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided an optical pickup actuator for actuating a lens holder having an object lens according to an interaction between coils and magnets, the optical pickup actuator including: a lens-seating portion formed on the lens holder to support the object lens; and a lens guide portion protruding from the lens-seating portion to securely support the object lens, wherein the lens guide portion has an adhesive confining groove in which adhesive can be injected to securely fix the object lens. 
     In another aspect of the present invention, there is provided an optical pickup actuator for actuating a lens holder having an object lens according to an interaction between coils and magnets, the optical pickup actuator, wherein the lens holder is provided at a side surface with a dissipation groove that does not directly contact a tracking coil. 
     In still another aspect of the present invention, there is provided an optical pickup actuator comprising: a lens holder having a lens-seating portion on which an object lens seats and a bobbin around which a focusing coil is wound, and a coil-supporting portion around which a tracking coil is wound, wherein the coil-supporting portion protrudes from a side surface of the lens holder and the side surface of the lens holder is provided with a coil-contacting portion contacting the tracking coil and a heat dissipation groove that does not contact the tracking coil. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
         FIGS. 1A and 1B  are schematic views of an optical pickup actuator according to the related art; and 
         FIGS. 2 through 4  are views illustrating an optical pickup actuator according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIGS. 2 through 4  are views illustrating an optical pickup actuator according to an embodiment of the present invention. 
     Referring to  FIGS. 2 through 4 , a lens holder  202  has first heat dissipation grooves  204  formed on a lens-seating portion  209  on which an object lens  201  seats, second heat dissipation grooves  225  formed on centers of opposite side surfaces of the lens holder  202 , and third heat dissipation grooves  232  formed on left and right portions of each of the opposite side surfaces of the lens holder  202 . 
     The object lens  201  seating on the lens-seating portion  209  is aligned with a beam-passing hole  203  surrounded by the lens-seating portion  209 . Lens guide portions  211  protrude from the lens-seating portion  209  to fixedly support the object lens  201 . The lens guide portions  211  are formed along a circumference having an inner diameter greater than an outer diameter of the object lens  201 . 
     The lens guide portions  211  are opened upward and toward a location where the object lens is located. For example, the lens guide portions  211  may be disposed about 90° apart. Each of the lens guide portion  211  has an adhesive confining groove  212  and an adhesive reinforcing projection  213  for dividing the adhesive confining groove  212  into two sections. The adhesive reinforcing projection  213  extends toward the object lens. 
     One or more reinforcing projections  213  may be formed on each lens guide portion  211 , having a height lower than that of the lens guide portion  211 . 
     Referring to  FIG. 4 , the adhesive is injected into the lens guide portion  211  after the object lens  201  seats on the lens-seating portion  209 . The adhesive may be a UV adhesive or a bond. The injected adhesive does not leak out of the lens guide portion  211  due to the internal structure of the lens guide portion  211 . At this point, since the adhesive reinforcing projection  213  is formed in the adhesive confining groove  212 , the adhesive force of the adhesive can be more enhanced. 
     As the adhesive is applied between he lens guide portions  211  and the object lens  201 , the adhesive force for bonding the object lens  201  to the lens holder  202  is further enhanced. 
     Accordingly, when the lens holder  202  is driven at a high speed, the resonance peak of the object lens  201  becomes identical to that of the lens holder  202 . 
     Meanwhile, the first heat dissipation grooves  204  are respectively formed on opposite portion of the lens-seating portion  209  that are adjacent to the coils. By the first heat dissipation grooves  204 , portions of the object lens  201  do not contact the lens-seating portion  209 . 
     Therefore, an amount of the heat transmitted to the object lens  201  through the lens-seating portion  209  can be reduced. 
     Also, second heat dissipation means is formed on the centers of the opposite surfaces of the lens holder  200 . The second heat dissipation means includes second coil contacting portions  223  and  224  on which portions where coil-supporting portions  221  and  222  will be formed are elevated so that upper and lower portions of the tracking coils  206  contact the coil supporting portions  221 . The second heat dissipation means further includes the second dissipation grooves  225  formed portions where a middle portion of an inner surface of the tracking coil  206  will contact. By the second dissipation grooves  225 , portions of the tracking coil  206  do not contact the lens holder  202 . 
     Here, each of the second heat dissipation grooves  225  may be unevenly formed and has a width wider than those of the second coil contacting portions  223  and  224 . 
     Also, third heat dissipation means is formed by stepping left and right sides of opposite surface of the lens holder  202 , which corresponds to inner surfaces of bobbins  230  around which the focusing coil  205  is wound. The third heat dissipation means includes third contacting portions  231  to which upper and lower portions of the focusing coil  205  contact. The third contacting portions  231  are elevated from the opposing surfaces of the lens holder  202 . The third heat dissipation means further includes third heat dissipation grooves  232  formed on the opposite surface of the lens holder  202 . The third heat dissipation grooves  232  correspond to the middle portion of the focusing coil  205 . Therefore, the middle portion of the focusing coil does not directly contact the lens holder  202  by the third dissipation grooves  232 . 
     Each of the third heat dissipation grooves  225  may be unevenly formed and has a width defined between the upper and lower bobbins  230 . Preferably, the width of the third heat dissipation grooves  225  is wider than those of the third coil contacting portions  231 . 
     The case where the coils are wound around the lens holder  202  having the above described first and second heat dissipation means is illustrated in  FIG. 3 . 
     The coils may be formed in a variety of shapes such as a rectangular shape or a trapezoid shape. 
     Referring to  FIG. 3 , the tracking coils  206  are wound around middle portions of the opposite surfaces of the lens holder  202  and the focusing and radial coils  205  and  207  are wound around left and right sides of the opposite surfaces of the lens holder  202 . The tracking coils  206  are supported by the coil supporting portions  221  and  222  and the middle portion of the inner surfaces of the tracking coils  206  are spaced away from the opposite surfaces of the lens holder  202  by the second heat dissipation grooves  225 . That is, since the upper and lower portions of the inner surfaces of the tracking coils  206  contact the second coil contacting portions  223  and  224 , the middle portions of the inner surfaces of the tracking coils  206  do not directly contact the lens holder  202  by the second dissipation grooves  225 . Accordingly, an amount of the heat generated by the tracking coils  206  and transmitted to the object lens can be reduced. 
     Furthermore, the focusing and radial coils  205  and  207  are dually wound. Middle portions of the inner surfaces of the focusing and radial coils  205  and  207  do not directly contact the tracking coil  206  by the third heat dissipation grooves  232  stepped inward from the third coil contacting portions  131 . Therefore, an amount of heat generated from the focusing and radial coils  205  and  207  and transmitted to the object lens can be reduced. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.