Patent ID: 7570456

Claim:
A spindle motor having a fluid dynamic bearing system comprising: a rotor having a cylindrical shaft ( 2 ), a first bearing disk ( 3 ) disposed at one end of the shaft and a second bearing disk ( 4 ) that is disposed on the shaft at a spacing to the first bearing disk in such a way that an annular disk-shaped space is formed between the two bearing disks ( 3 ; 4 ); a stator having an annular disk-shaped component ( 5 ) that is disposed in the annular disk-shaped space formed by the rotor, the respective opposing bearing surfaces of the stator and of the rotor being separated from one another by a bearing gap ( 6 ) filled with a fluid medium; at least one radial bearing ( 7 ) formed between the outside circumference of the shaft ( 2 ) and the inside circumference of the annular disk-shaped component ( 5 ); and two axial bearings ( 9 ; 10 ) formed by the two end faces of the annular disk-shaped component ( 5 ) and the respective opposing end faces of the bearing disks ( 3 ; 4 ); and an electromagnetic drive unit characterized in that the radial bearing ( 7 ) is defined by surface patterns ( 8 ) formed on the shaft ( 2 ) and/or on the annular disk-shaped component ( 5 ), the surface patterns generating a pumping action on the fluid medium directed towards the center of the radial bearing.