Fluid dynamic bearing apparatus

Abstract

A rotation shaft is supported in a sleeve in a fluid dynamic bearing apparatus. Fluid is filled between the rotation shaft and the sleeve. A dust catcher is disposed between the rotation shaft and the sleeve. The fluid dynamic bearing apparatus allows the fluid to flow within the space between the rotation shaft and the sleeve during the rotation of the rotation shaft. The dust catcher catches fine dusts contained in the fluid. The diffusion of the fine dusts can thus be prevented in the fluid. The viscosity of the fluid cannot increase. The rotation shaft keeps smoothly rotating in an expected manner.

1 . A fluid dynamic bearing apparatus comprising: 
 a rotation shaft;    a sleeve supporting the rotation shaft;    fluid filled between the rotation shaft and the sleeve; and    a dust catcher disposed between the rotation shaft and the sleeve.    
   
   
       2 . The fluid dynamic bearing apparatus according to  claim 1 , wherein said dust catcher is fixed to the sleeve.  
   
   
       3 . The fluid dynamic bearing apparatus according to  claim 2 , wherein said dust catcher is made of a synthetic resin.  
   
   
       4 . The fluid dynamic bearing apparatus according to  claim 3 , wherein through holes are defined in the dust catcher.  
   
   
       5 . The fluid dynamic bearing apparatus according to  claim 4 , wherein said dust catcher is an electret filter.  
   
   
       6 . A fluid dynamic bearing apparatus comprising: 
 a rotation shaft;    a sleeve supporting the rotation shaft, a groove being defined on an inner surface of the sleeve;    fluid filled between the rotation shaft and the sleeve; and    a plate member attached to an inlet of the groove,    wherein    through holes are defined in the plate member.    
   
   
       7 . The fluid dynamic bearing apparatus according to  claim 6 , wherein said plate member is integral to the sleeve.  
   
   
       8 . A fluid dynamic bearing apparatus comprising: 
 a rotation shaft;    a sleeve supporting the rotation shaft;    fluid filled between the rotation shaft and the sleeve; and    a corrosive added into the fluid.    
   
   
       9 . A fluid dynamic bearing apparatus comprising: 
 a rotation shaft;    a sleeve supporting the rotation shaft, an inner surface of the sleeve being opposed to an outer surface of the rotation shaft;    fluid filled between the rotation shaft and the sleeve;    grooves defined on the inner surface of the sleeve so as to generate dynamic pressure in the fluid; and    depressions defined on the inner surface of the sleeve.    
   
   
       10 . The fluid dynamic bearing apparatus according to  claim 9 , wherein said depressions are located within the grooves.  
   
   
       11 . A fluid dynamic bearing apparatus comprising: 
 a rotation shaft;    a sleeve supporting the rotation shaft; and    a prevention member designed to prevent inclination of the rotation shaft standing still.    
   
   
       12 . The fluid dynamic bearing apparatus according to  claim 11 , wherein said prevention member is a protrusion formed on the sleeve so as to extend toward the rotation shaft.  
   
   
       13 . The fluid dynamic bearing apparatus according to  claim 12 , wherein a gap is defined between the prevention member and the rotation shaft when the rotation shaft rotates.  
   
   
       14 . The fluid dynamic bearing apparatus according to  claim 11 , wherein said prevention member is a protrusion formed on the rotation shaft so as to extend toward the sleeve.  
   
   
       15 . The fluid dynamic bearing apparatus according to  claim 14 , wherein a gap is defined between the prevention member and the sleeve when the rotation shaft rotates.