Optical pickup and disc drive device

Abstract

An objective lens driving device is to be improved in sensitivity and reduced in size and thickness. To this end, an objective lens driving device includes a stationary block arranged on a stationary plate provided on a movable base, a movable block holding an objective lens and moved along the focusing direction, the tracking direction and the tilt direction, support springs for supporting the movable block with respect to the stationary block, a first magnetic circuit for causing movement of the movable block along the focusing direction and along the tracking direction, and a second magnetic circuit for causing movement of the movable block along the tilt direction. The second magnetic circuit includes a pair of tilt magnets, each having two poles so that N poles and S poles lie along the tangential direction, and a pair of tilt coils facing the tilt magnets and each having an axis of winding wire direction along the tangential direction. The tilt magnets and the tilt coils are mounted to the movable block and the stationary block, respectively. An objective lens and the second magnetic circuit are arranged on the opposite sides along the tangential direction with the first magnetic circuit in-between.

1 . An optical pickup having a movable base moved along the radial direction of a disc-shaped recording medium loaded on a disc table; and an objective lens driving device arranged on said movable base, wherein the objective lens driving device comprises: 
 a stationary plate provided on said movable base;    a stationary block arranged on said stationary plate and secured to said movable base;    a movable block holding said objective lens and operated relative to said stationary block along a focusing direction, which is a direction towards and away from a recording surface of the disc-shaped recording medium, along a tracking direction, which is a radial direction of said disc-shaped recording medium, and along a tilt direction, which is a direction about an axis extending along the tangential direction perpendicular to the radial direction of the disc-shaped recording medium;    a plurality of support springs for movably supporting said movable block relative to said stationary block;    a first magnetic circuit for causing movement of said movable block along said focusing direction or along said tracking direction; and    a second magnetic circuit for causing movement of said movable block along said tilt direction;    said second magnetic circuit including    a pair of tilt magnets each magnetized to two poles so that N and S poles are arranged along the focusing direction, said paired tilt magnets being spaced apart from each other along said radial direction, and a pair of tilt coils arranged facing said paired tilt magnets, each of said tilt coils having an axis of winding wire direction corresponding to the tangential direction;    said paired tilt magnets being provided to said movable block;    said paired tilt coils being provided to said stationary block; and    said objective lens and the second magnetic circuit being located on both sides of said first magnetic circuit along the tangential direction.    
   
   
       2 . The optical pickup according to  claim 1 , wherein 
 there is provided a tilt yoke by bending a portion of said stationary plate on the opposite side of said tilt magnet along the tangential direction with said tilt coil in-between.    
   
   
       3 . The optical pickup according to  claim 1 , wherein a back yoke is provided on the surface of said tilt magnet opposite to the surface thereof facing said tilt coil.  
   
   
       4 . An optical pickup having a movable base moved along the radial direction of a disc-shaped recording medium loaded on a disc table and an objective lens driving device arranged on said movable base, wherein said objective lens driving device comprises: 
 a stationary block secured to said movable base;    a movable block holding said objective lens and operated relative to said stationary block along a focusing direction, which is a direction towards and away from a recording surface of the disc-shaped recording medium, along a tracking direction, which is a radial direction of said disc-shaped recording medium, and along a tilt direction, which is a direction about an axis extending along the tangential direction perpendicular to the radial direction of the disc-shaped recording medium;    a plurality of support springs for movably supporting said movable block relative to said stationary block;    a first magnetic circuit for causing movement of said movable block along said focusing direction or along said tracking direction; and    a second magnetic circuit for causing movement of said movable block along said tilt direction;    said second magnetic circuit including    a pair of tilt magnets each magnetized to two poles so that N and S poles are arranged along the focusing direction, said paired tilt magnets being spaced apart from each other along said radial direction, and a pair of tilt coils arranged facing said paired tilt magnets, each of said tilt coils having an axis of winding wire direction corresponding to the tangential direction;    said paired tilt magnets being provided to said movable block;    said paired tilt coils being provided to said stationary block; and    a back yoke being arranged on the surface of said tilt magnet opposite to the surface thereof facing said tilt coil.    
   
   
       5 . A disc drive device comprising a disc table for loading a disc-shaped recording medium thereon and an optical pickup for radiating laser light via an objective lens to the disc-shaped recording medium loaded on said disc table, said optical pickup including a movable base moved along the radial direction of a disc-shaped recording medium loaded on a disc table, and an objective lens driving device arranged on said movable base, wherein said objective lens driving device comprises: 
 a stationary plate provided on said movable base;    a stationary block arranged on said stationary plate and secured to said movable base;    a movable block for holding said objective lens and operated relative to said stationary block along a focusing direction, which is a direction towards and away from a recording surface of the disc-shaped recording medium, along a tracking direction, which is a radial direction of said disc-shaped recording medium, and along a tilt direction, which is a direction about an axis extending along the tangential direction perpendicular to the radial direction of the disc-shaped recording medium;    a plurality of support springs for movably supporting said movable block relative to said stationary block;    a first magnetic circuit for causing movement of said movable block along said focusing direction or along said tracking direction; and    a second magnetic circuit for causing movement of said movable block along said tilt direction;    said second magnetic circuit including    a pair of tilt magnets each magnetized to two poles so that N and S poles are arranged along the focusing direction, said paired tilt magnets being spaced apart from each other along said radial direction, and a pair of tilt coils arranged facing said paired tilt magnets, each of said tilt coils having an axis of winding wire direction corresponding to the tangential direction;    said paired tilt magnets being provided to said movable block;    said paired tilt coils being provided to said stationary block; and    said objective lens and the second magnetic circuit being located on both sides of said first magnetic circuit along the tangential direction.    
   
   
       6 . The disc drive device according to  claim 4 , wherein 
 there is provided a tilt yoke by bending a portion of said stationary plate on the opposite side of said tilt magnet along the tangential direction with said tilt coil in-between.    
   
   
       7 . The disc drive device according to  claim 4 , wherein a back yoke is provided on the surface of said tilt magnet opposite to the surface thereof facing said tilt coil.  
   
   
       8 . A disc drive device comprising a disc table for loading a disc-shaped recording medium thereon and an optical pickup for radiating laser light via an objective lens to the disc-shaped recording medium loaded on said disc table, said optical pickup including a movable base moved along the radial direction of a disc-shaped recording medium loaded on a disc table and an objective lens driving device arranged on said movable base wherein said objective lens driving device comprises: 
 a stationary block secured to said movable base;    a movable block holding said objective lens and operated relative to said stationary block along a focusing direction, which is a direction towards and away from a recording surface of the disc-shaped recording medium, along a tracking direction, which is a radial direction of said disc-shaped recording medium, and along a tilt direction, which is a direction about an axis extending along the tangential direction perpendicular to the radial direction of the disc-shaped recording medium;    a plurality of support springs for movably supporting said movable block relative to said stationary block;    a first magnetic circuit for causing movement of said movable block along said focusing direction or along said tracking direction; and    a second magnetic circuit for causing movement of said movable block along said tilt direction;    said second magnetic circuit including    a pair of tilt magnets each magnetized to two poles so that N and S poles are arranged along the focusing direction, said paired tilt magnets being spaced apart from each other along said radial direction, and a pair of tilt coils arranged facing said paired tilt magnets, each of said tilt coils having an axis of winding wire direction corresponding to the tangential direction;    said paired tilt magnets being provided to said movable block;    said paired tilt coils being provided to said stationary block; and    a back yoke being provided on the surface of said tilt magnet opposite to the surface thereof facing said tilt coil.