An auto balancing system of a spindle motor is provided to improve performance of the motor by distributing balls when stopping the spindle motor. A turntable(160) is combined in a rotation axis. The turntable is rotated with the rotation axis. The turntable supports the disc(50). A cover(180) is coupled with the turntable. A ring type space(160a) is positioned between the cover and the turntable. A plurality of balls are stored in the ring type space. The plurality of balls reduce the vibration when the rotation axis and the turntable are rotated. A plurality of dividing protrusions disperses the plurality of balls into the ring type space. The plurality of partition protrusions are formed in the cover with a predetermined interval. The cross section of each partition protrusion is a convex curved surface.
展开▼
