Patent ID: 7180703

Claim:
A disk drive comprising: (a) a disk; (b) a head actuated over the disk; and (c) a spindle motor for rotating the disk, the spindle motor comprising a rotating component, a stationary component, a first and second bearing assembly disposed between the rotating component and stationary component for rotating the rotating component about the stationary component, wherein: the disk is attached to the rotating component; the first bearing assembly comprises a first stationary component surface and a first rotating component surface; an anionic lubricant is disposed between the first stationary component surface and the first rotating component surface such that a first voltage forms between the first stationary component surface and the first rotating component surface when the rotating component rotates about the stationary component; the second bearing assembly comprises a second stationary component surface and a second rotating component surface; a cationic lubricant is disposed between the second stationary component surface and the second rotating component surface such that a second voltage forms between the second stationary component surface and the second rotating component surface when the rotating component rotates about the stationary component; and a polarity of the second voltage being opposite a polarity of the first voltage to thereby reduce the potential at the disk surface.