Optical pickup

Abstract

An optical pickup comprises an objective-lens driving device including a movable section provided with an objective lens, a focusing coil, and tracking coils, and a fixed section provided with a single magnetic circuit having a magnetic gap, the focusing coil and the tracking coils being disposed in the magnetic gap. The point of application of a tracking-driving force, the point of application of a result force of focusing-driving forces occurring in and outside the magnetic gap, and the position of the center of gravity of the movable section are made to substantially coincide with each other. In addition, the objective lens and the magnetic circuit are disposed within an area of a window in a lower shell of a optical disk. Further, a through hole for accommodating a lower portion of a yoke of the magnetic circuit is provided in a mounting base on which the objective-lens driving device is mounted. An inclining fulcrum and a height adjusting means for inclining the objective-lens driving device about the inclining fulcrum are provided in the vicinities of the through hole.

1. An optical pickup device comprising:
 an objective-lens driving device for driving an objective lens, which includes a magnetic circuit;    an optical system for transmitting and receiving light to and from said objective lens; and    a base having a through hole formed therein, on which said objective-lens driving device and said optical system are mounted, and wherein at least a portion of said magnetic circuit of said objective-lens driving device is accommodated in said through hole.    
     
     
       2. An optical pickup device as claimed in  claim 1 , further comprising a movable plate integrally formed with a yoke as said magnetic circuit, said yoke having a substantially U-shaped cross-section, on which said objective-lens driving device is mounted. 
     
     
       3. An optical pickup device as claimed in  claim 2  , comprising:
   an objective - lens driving device for driving an objective lens, which includes a magnetic circuit including a yoke, and resiliently supporting members for supporting a movable part of the objective - lens driving device;    
   an optical system for transmitting and receiving light to and from said objective lens;    
   a base having a through hole formed therein, on which said objective - lens driving device and said optical system are mounted, and wherein at least a portion of said yoke of said magnetic circuit of said objective - lens driving device is accommodated in said through hole; and    
   a movable plate integrally formed with said yoke as said magnetic circuit, said yoke having a substantially U - shaped cross - section, on which said objective - lens driving device is mounted,   
 wherein an inclination of said movable plate is adjusted relative to said base.  
 
     
     
       4. An optical pickup device as claimed in  claim 3 ,
   wherein said resiliently supporting members are made of wires.     
     
     
       5. An optical pickup device as claimed in  claim 3 ,
   wherein at least four resiliently supporting members are provided.     
     
     
       6. An optical pickup device as claimed in  claim 3 , wherein said resiliently supporting members support said movable part of the objective- lens driving system in a cantilevered manner.   
     
     
       7. An optical pickup device comprising:
   an objective - lens driving device for driving an objective lens, which includes a magnetic circuit including a yoke, and resiliently supporting members for supporting a movable part of the objective - lens driving device;        an optical system for transmitting and receiving light to and from said objective lens; and        a base having a through hole formed therein, on which said objective - lens driving device and said optical system are mounted, and wherein at least a portion of said yoke of said magnetic circuit of said objective - lens driving device is accommodated in said through hole; and        wherein said objective - lens driving device includes coils for generating a driving force to drive the objective lens, and        said resiliently supporting members serve as paths for supplying electric current to the coils.     
     
     
       8. An optical pickup device as claimed in  claim 7 ,
   wherein said resiliently supporting members are made of wires.     
     
     
       9. An optical pickup device as claimed in  claim 7 ,
   wherein at least four resiliently supporting members are provided.     
     
     
       10. An optical pickup device as claimed in  claim 7 , wherein said resiliently supporting members support said movable part of the objective- lens driving system in a cantilevered manner.   
     
     
       11. An optical pickup device, comprising:
   an objective - lens driving device for driving an objective lens, which includes a magnetic circuit, and resiliently supporting members for supporting a movable part of the objective - lens driving device;        an optical system for transmitting and receiving light to and from said objective lens;        a base having a through hole formed therein, on which said objective - lens driving device and said optical system are mounted, and wherein at least a portion of said magnetic circuit of said objective - lens driving device is accommodated in said through hole; and        a movable plate integrally formed with a yoke as said magnetic circuit, said yoke having a substantially U - shaped cross - section, on which said objective - lens driving device is mounted,        wherein an inclination of said movable plate is adjusted relative to said base.     
     
     
       12. An optical pickup device, comprising:
   an objective - lens driving device for driving an objective lens, which includes a magnetic circuit, and resiliently supporting members for supporting a movable part of the objective - lens driving device;        an optical system for transmitting and receiving light to and from said objective lens; and        a base having a through hole formed therein, on which said objective - lens driving device and said optical system are mounted, and wherein at least a portion of said magnetic circuit of said objective - lens driving device is accommodated in said through hole; and        wherein said objective - lens driving device includes coils for generating a driving force to drive the objective lens; and        said resiliently supporting members serve as paths for supplying electric current to the coils.