Patent Abstract:
Provided is an optical pickup actuator. The optical pickup actuator includes: a lens holder for holding an object lens; a focusing coil disposed at the lens holder; a tracking coil disposed at the lens holder; a radial coil wound at a coil holder at which the focusing coil is wound; and multipolar magnets disposed at positions facing the focusing coil, the tracking coil, and the radial coil.

Full Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical pickup actuator for improving a coil winding structure of a lens holder. 
   2. Description of the Background Art 
   Optical pickup actuator refers to a device for recording information or reproducing the recorded information following an optical recording medium. The optical pickup actuator constantly maintains a relative position between an objective lens and the optical recording medium by moving a lens holder for holding the objective lens. 
     FIGS. 1 to 3  are views illustrating a conventional optical pickup actuator. 
   The optical pickup actuator  100  includes a lens holder  102  for holding an objective lens at its center; and a magnetic circuit disposed at one side of the lens holder  102  and activating the lens holder  102 . 
   The magnetic circuit includes focusing coils  104 , tracking coils  105 , a yoke  107 , and multipolar magnets  110   a  to  110   d.    
   The focusing coils  104  are disposed at the left and right of both side surfaces of the lens holder  102  to perform focusing operations. The focusing coil  104  is positioned to face a horizontal boundary  111  between magnets having different polarities. 
   The tracking coils  105  are disposed at the centers of both side surfaces of the lens holder  102  to perform tracking operations. The tracking coil  105  is positioned to face a vertical boundary  112  between magnets having different polarities. 
   The radial coil  103  is disposed at an upper side of the lens holder  102  to perform a radial tilting operation. The radial coil  103  is disposed at a circumference surface of the lens holder  102 . A portion of the radial coil  103  is positioned to face the vertical boundary  112  between the magnets having the different polarities. 
   The multipolar magnets are comprised of rectangular magnets  110   c  and  110   d  disposed at their lower sides, and rectangular magnets  110   a  and  110   b  disposed at upper sides of and between the magnets  110   c  and  110   d.    
   The magnets  110   a  to  110   d  are respectively fixed to an inner surface of the yoke  107 , which is formed of ferromagnetic substance and disposed adjacently to the lens holder  102 . The yoke  107  functions as a path for magnetic fields generated from the magnets  110   a  to  110   d.    
   Wire suspensions  106  are fixed at their one ends to both side surfaces of the lens holder  102 , and fixed at their other ends to a frame provided at one side of the lens holder  102 . The wire suspension  106  supports the lens holder  102 , and supplies electric current. 
   An operation of the optical pickup actuator  100  will be described as follows. 
   When electric current flows through the focusing coil  104 , the focusing coil  104  is interacted with the magnetic field generated from the horizontal boundary  111  between the facing magnets and is vertically forced due to the interaction, thereby activating a focusing servo. 
   When the electric current flows through the tracking coil  105 , the tracking coil  105  is interacted with the magnetic field generated from the vertical boundary  112  between the facing magnets and is horizontally forced due to the interaction, thereby activating a tracking servo. 
   When the electric current flows through the radial coil  103 , the radial coil  103  is interacted with the magnetic field generated from the horizontal boundary  111  between the facing magnets and is forced upward and downward due to the interaction, thereby performing the radial tilting operation. 
   As shown in  FIG. 2 , the radial tilting operation refers to the operation of forcing the lens holder  102  upward at one side and downward at the other side, thereby rotating the lens holder  102 . 
   In the optical pickup actuator  100 , the lens holder  102  is moved using an interaction between the magnet and the coil, thereby minimizing error of a light signal. 
   However, the conventional optical pickup actuator  100  has a drawback in that it requires a structure for winding the radial coil  103  on the lens holder  102 , and a separate process for winding the radial coil  103 . 
   SUMMARY OF THE INVENTION 
   Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the background art. 
   An object of the present invention is to provide an optical pickup actuator for forming a radial coil at a lens holder without a separate structure for winding the radial coil. 
   Another object of the present invention is to provide an optical pickup actuator for freely selecting a winding position and type of a radial coil. 
   A further another object of the present invention is to provide an optical pickup actuator for facilitating a process of winding a radial coil. 
   To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided an optical pickup actuator including: a lens holder for holding an object lens; a focusing coil disposed at the lens holder; a tracking coil disposed at the lens holder; a radial coil wound at a coil holder at which the focusing coil is wound; and multipolar magnets disposed at positions facing the focusing coil, the tracking coil, and the radial coil. 
   In another aspect of the present invention, there is provided an optical pickup actuator including: a lens holder for holding an objective lens; multipolar magnets disposed adjacently to the lens holder; a focusing coil wound on the lens holder, and facing a horizontal boundary between the multipolar magnets and vertically forced depending on applied electric current; a tracking coil wound on the lens holder, and facing a vertical boundary between the multipolar magnets and horizontally forced depending on the applied electric current; and a radial coil wound on the lens holder, and facing a horizontal boundary between the multipolar magnets and forced upward at one side and downward at the other side depending the applied electric current. 
   In a further another aspect of the present invention, there is provided an optical pickup actuator including: a lens holder for holding an objective lens; a focusing coil disposed at the lens holder, and performing a focusing operation; a tracking coil disposed at the lens holder, and performing a tracking operation; a radial coil having at least one part adhered to the focusing coil, and performing a radial tilting operation; and multipolar magnets disposed at positions facing the focusing coil, the tracking coil, and the radial coil. 
   In a still another aspect of the present invention, there is provided an optical pickup actuator including: a lens holder for holding an objective lens; focusing coils respectively disposed at both side surfaces of the lens holder, and performing a focusing operation depending applied electric current; tracking coils respectively disposed at the both side surfaces of the lens holder, and performing a tracking operation depending the applied electric current; radial coils respectively disposed at the both side surfaces of the lens holder, and performing a radial tilting operation depending the applied electric current; and multipolar magnets disposed at positions facing the focusing coil, the tracking coil, and the radial coil. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in detail with reference to the following drawings in which like numerals refer to like elements. 
       FIGS. 1 to 3  are views illustrating a conventional optical pickup actuator; 
       FIGS. 4 to 7  are views illustrating an optical pickup actuator according to the first embodiment of the present invention; 
       FIGS. 8 and 9  are views illustrating an optical pickup actuator according to the second embodiment of the present invention; 
       FIGS. 10 to 14  are views illustrating an optical pickup actuator according to the third embodiment of the present invention; 
       FIGS. 15 and 16  are views illustrating an optical pickup actuator according to the fourth embodiment of the present invention; and 
       FIGS. 17 to 20  are views illustrating an optical pickup actuator according to the fifth embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will be described in a more detailed manner with reference to the drawings. 
     FIGS. 4 to 7  are views illustrating an optical pickup actuator according to the first embodiment of the present invention. 
   The optical pickup actuator includes a lens holder  202  for holding an objective lens  201 . The lens holder  202  is supported by a wire suspension  206 . The wire suspension  206  not only supports the lens holder  202 , but also supplies electric current to activate the optical pickup actuator. 
   Focusing coils  204 , tracking coils  205  and radial coils  203   a  to  203   d  are disposed at both side surfaces of the lens holder  202 . 
   The focusing coils  204  are disposed at the left and right of the both side surfaces of the lens holder  202 , and the tracking coils  205  are disposed at centers of the both side surfaces of the lens holder  202 . 
   The radial coils  203   a  to  203   d  are adhered at inner sides of the focusing coils  204 . 
   First, the radial coils  203   a  to  203   d  can be wound on the coil holders  209 , and then the focusing coils  204  can be wound on the radial coils  203   a  to  203   d  wound on the coil holders  209 , to form the radial coils  203   a  to  203   d  together with the focusing coils  204 . 
   In other words, the radial coils  203   a  to  203   d  are wound on the coil holders  209  having the focusing coil  204  wound thereon. 
   As such, in the inventive optical pickup actuator, the radial coils  203   a  to  203   d  are wound on the coil holders  209  together with the focusing coil  204 , thereby not requiring a separate fixed structure for winding the radial coils  203   a  to  203   d  on the lens holders  202 . 
   The focusing coils  204  and the radial coils  203   a  to  203   d  are positioned to face horizontal boundaries  211  between magnets having different polarities, and the tracking coil  205  is positioned to face a vertical boundary  212  between magnets having different polarities. 
   The magnets are comprised of rectangular magnets  210   c  and  210   d  disposed at their lower sides, and rectangular magnets  210   a  and  210   b  disposed at upper sides of and between the rectangular magnets  210   c  and  210   d . The magnets  210   a  to  210   d  are respectively fixed to an inner surface of a yoke  207 , which is formed of ferromagnetic substance and disposed adjacently to the lens holder  202 . The yoke  207  provides a path for magnetic fields generated from the magnets  210   a  to  210   d.    
   The radial coils  203   a  to  203   d  can be wound in various manners for a radial tilting operation. 
   In one example, the radial coils  203   a  and the  203   b  are connected in parallel, and the radial coils  203   c  and  203   d  are also connected in parallel. The radial coils  203   a  and  203   d  are connected in series, and the radial coils  203   b  and  203   c  are also connected in series. 
   In another example, each of the radial coils  203   a  to  203   d  can be independently wound to perform the radial tilting operation by controlling the direction of electric current. 
   In a further another example, the radial coils  203   a  to  203   d  can be wound in different directions to perform the radial tilting operation. 
   Due to the radial tilting operation of the radial coils  203   a  to  203   d , the lens holder  202  is forced downward at one side and upward at the other side as shown in  FIG. 7 . 
   In other words, the both sides of the lens holder  202  are respectively forced in opposite directions so that the radial coils  203   a  to  203   d  can perform the radial tilting operation. 
   An operation of the optical pickup actuator will be described as follows. 
   First, when the electric current flows through the focusing coil  204 , the focusing coil  204  is interacted with a magnetic field generated from the horizontal boundary  211  between the facing magnets and is vertically forced due to the interaction, thereby activating a focusing servo. 
   When electric current flows through the tracking coil  205 , the tracking coil  205  is interacted with a magnetic field generated from the vertical boundary  212  between the facing magnets and is horizontally forced due to the interaction, thereby activating a tracking servo. 
   When electric current flows through the radial coils  203   a  to  203   d , the radial coils  203   a  to  203   d  are interacted with the magnetic field generated from the horizontal boundary  211  between the facing magnets and are forced upward and downward due to the interaction, thereby performing the radial tilting operation. 
   By the parallel connection, the direction of the applied electric current, and the winding direction of the radial coils  203   a  to  203   d , the radial coils  203   b  and  203   c  and the radial coils  203   a  and  203   d  are forced in different directions, respectively. 
   For example, in  FIG. 7 , when the electric current counterclockwise flows through the radial coils  203   a  and  203   b , the radial coil  203   a  is forced downward and the radial coil  203   b  is forced upward due to opposite magnetic poles of the magnets disposed at upper and lower positions of the horizontal boundary  211 . 
   Accordingly, the radial tilting operation of the radial coils  203   a  to  203   d  can be smoothly performed. 
   In the following optical pickup actuators according to other embodiments of the present invention, a type of a radial coil will be concentratively described, and a detailed description of other constituent elements will be omitted. 
     FIGS. 8 and 9  are views illustrating an optical pickup actuator according to the second embodiment of the present invention. 
     FIG. 8  does not show a lens holder, and shows only an objective lens  301 , focusing coils  304 , radial coils  303  and tracking coils  305 . 
   In the inventive optical pickup actuator, the focusing coil  304  is first wound and then, the radial coil  303  is wound on the focusing coil  304 . 
   In the same manner as in the first embodiment, the radial coils  303  are positioned to face horizontal boundaries  311  between magnets  310   a  to  310   d  disposed at a yoke  307 . 
     FIGS. 10 to 14  are views illustrating an optical pickup actuator according to the third embodiment of the present invention. 
   The optical pickup actuator includes a lens holder  402  for holding an objective lens  401 . The lens holder  402  is supported by a wire suspension  406 . The wire suspension  406  not only supports the lens holder  402 , but also supplies electric current to activate the optical pickup actuator. 
   Focusing coils  404 , tracking coils  405  and radial coils  403   a  to  403   d  are disposed at both side surfaces of the lens holder  402 . 
   The radial coils  403   a  to  403   d  are disposed between the focusing coils  404  and the lens holder  402 . 
   The radial coils  403   a  to  403   d  can be first wound on coil holders  409 , and then the focusing coils  404  can be wound on the coil holders  409  and in front of the radial coils  403   a  to  403   d , so that the radial coils  403   a  to  403   d  and the focusing coils  404  can be wound on one coil holders  409 . 
   The focusing coils  404  and the radial coils  403   a  to  403   d  are positioned to face horizontal boundaries  411  between magnets having different polarities, and the tracking coil  405  is positioned to face a vertical boundary  412  between magnets having different polarities. 
   The magnets are comprised of rectangular magnets  410   c  and  410   d  disposed at their lower sides, and rectangular magnets  410   a  and  410   b  disposed at upper sides of and between the rectangular magnets  410   c  and  410   d . The magnets  410   a  to  410   d  are respectively fixed to an inner surface of a yoke  407 , which is formed of ferromagnetic substance and disposed adjacently to the lens holder  402 . 
   Due to the radial tilting operation of the radial coils  403   a  to  403   d , as shown in  FIG. 14 , the lens holder  402  is forced downward at one side and upward at the other side. 
   In other words, the both sides of the lens holder  402  are respectively forced in opposite directions such that the radial coils  403   a  to  403   d  can perform the radial tilting operation. 
   An operation of the optical actuator will be described as follows. 
   First, when electric current flows through the focusing coil  404 , the focusing coil  404  is interacted with a magnetic field generated from the horizontal boundary  411  between the facing magnets and is vertically forced due to the interaction, thereby activating a focusing servo. 
   When electric current flows through the tracking coil  405 , the tracking coil  405  is interacted with a magnetic field generated from the vertical boundary  412  between the facing magnets and is horizontally forced due to the interaction thereby activating a tracking servo. 
   When electric current flows through the radial coils  403   a  to  403   d , the radial coils  403   a  to  403   d  are interacted with the magnetic field generated from the horizontal boundary  411  between the facing magnets and are forced upward and downward due to the interaction, thereby performing the radial tilting operation. 
   By the parallel connection, the direction of the applied electric current, and the winding direction of the radial coils  403   a  to  403   d , the radial coils  403   b  and  403   c  and the radial coils  403   a  and  403   d  are forced in different directions, respectively. 
   For example, in  FIG. 14 , when the electric current counterclockwisely flows through the radial coils  403   a  and  403   b , the radial coil  403   a  is forced downward and the radial coil  403   b  is forced upward due to opposite magnetic poles of the magnets disposed at upper and lower positions of the horizontal boundary  411 . 
   Accordingly, the radial tilting operation of the radial coils  403   a  to  403   d  can be smoothly performed. 
     FIGS. 15 and 16  are views illustrating an optical pickup actuator according to the fourth embodiment of the present invention. 
     FIG. 15  does not show a lens holder, and shows only an objective lens  501 , focusing coils  504 , radial coils  503   a  to  503   d , and tracking coils  505 . 
   In the inventive optical pickup actuator, the focusing coils  504  are first wound and then, the radial coils  503   a  to  503   d  are wound in front of the focusing coils  504 . 
   In other words, the focusing coils  504  are positioned between the lens holder and the radial coils  503   a  to  503   d.    
   The radial coils  503   a  to  503   d  of the fourth embodiment are changed in position in the third embodiment of the present invention. 
   In the same manner as in the third embodiment, the radial coils  503   a  to  503   d  and the focusing coils  504  are positioned to face horizontal boundaries  511  between magnets  510   a  to  510   d  disposed at a yoke  507 . 
     FIGS. 17 to 20  are views illustrating an optical pickup actuator according to the fifth embodiment of the present invention. 
   The optical pickup actuator includes a lens holder  602  for holding an objective lens  601 . The lens holder  602  is supported by a wire suspension  606 . The wire suspension  606  not only supports the lens holder  602 , but also supplies electric current to activate the optical pickup actuator. 
   Focusing coils  604   a  to  604   d , tracking coils  605 , and radial coils  603   a  and  603   b  are disposed at both side surfaces of the lens holder  602 . 
   The radial coils  603   a  and  603   b  are disposed at circumferences of the focusing coils  604   a  and  604   b  and at circumferences of the focusing coils  604   c  and  604   d . Each of the radial coils  603   a  and  603   b  forms one loop at both sides of the lens holder  602 . 
   The focusing coils  604   a  and  604   b  are first wound on coil holders  609 , and then the radial coil  603   a  is wound as one loop on the circumferences of the focusing coils  604   a  and  604   b.    
   Similarly, the focusing coils  604   c  and  604   d  are first wound on the coil holders  609 , and then the radial coil  603   b  is wound as one loop on the circumferences of the focusing coils  604   c  and  604   d.    
   The focusing coils  604   a  to  604   d  and the radial coils  603   a  and  603   b  are positioned to face horizontal boundaries  611  between magnets having different polarities, and the tracking coil  605  is positioned to face a vertical boundary  612  between magnets having different polarities. 
   The magnets are comprised of rectangular magnets  610   c  and  610   d  disposed at their lower sides, and rectangular magnets  610   a  and  610   b  disposed at upper sides of and between the rectangular magnets  610   c  and  610   d . The magnets  610   a  to  610   d  are respectively fixed to an inner surface of a yoke  407 , which is formed of ferromagnetic substance and disposed adjacently to the lens holder  602 . 
   Due to the radial tilting operation of the radial coils  603   a  and  603   b , as shown in  FIG. 20 , the lens holder  602  is forced downward at one side and upward at the other side. 
   In other words, the both sides of the lens holder  602  are respectively forced in opposite directions such that the radial coils  603   a  and  603   b  can perform the radial tilting operation. 
   An operation of the optical pickup actuator will be described as follows. 
   First, when electric current flows through the focusing coils  604   a  to  604   d , the focusing coils  604   a  to  604   d  are interacted with magnetic fields generated from the horizontal boundaries  611  between the facing magnets and are vertically forced due to the interaction, thereby activating a focusing servo. 
   When electric current flows through the tracking coil  605 , the tracking coil  605  is interacted with a magnetic field generated from the vertical boundary  612  between the facing magnets and is horizontally forced due to the interaction, thereby activating a tracking servo. 
   When electric current flows through the radial coils  603   a  and  603   b , the radial coils  603   a  and  603   b  are interacted with the magnetic fields generated from the horizontal boundaries  611  between the facing magnets and are forced upward and downward due to the interaction, thereby performing the radial tilting operation. 
   For example, in  FIG. 20 , when the electric current counterclockwise flows through the radial coil  603   a , the radial coil  603   a  is forced upward due to opposite magnetic poles of the magnets disposed at upper and lower positions of the horizontal boundary  611 . 
   Accordingly, the radial tilting operation of the radial coil  603   a  can be smoothly performed. 
   As described above, the inventive optical pickup actuator has an advantage in that the radial coil is wound together with the focusing coil at a position of the lens holder, thereby simplifying a shape and a manufacture process of the lens holder. 
   The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Technology Classification (CPC): 6