Disc drive spindle motor with controlled resistance pathway from disc to ground

Abstract

A disc drive for storing and retrieving data from at least one memory storage disc includes a drive base and a spindle motor. The spindle motor includes a rotor hub, a shaft, a bearing unit. The bearing unit rotatably supports the rotor hub about an axis. A controlled resistance electrical pathway is established from the rotor hub to ground to control disc potential and to prevent excess static charge buildup. In one embodiment, the spindle motor includes structural elements made of a conducting plastic having a controlled resistance to establish a controlled resistance electrical pathway from the rotor hub to ground. In a second embodiment, the shaft of the spindle motor includes a conductive contact button electrically connected to the shaft and operatively coupled with a contact shield electrically grounded by an electrical conductor having a controlled resistance. In another embodiment, the spindle motor includes a rod made of conductive material extending from an electrically grounded contact shield and received within the shaft. An electrical pathway between the shaft and the rod is established by a conducting fluid between the rod and the shaft. Alternatively, the electrical pathway from the shaft to the rod is established by a conducting unit. The conducting unit includes a seal, a magnetic conductive material, and a ferro-fluid. The seal is positioned within the shaft. The magnetic conductive material is coupled to the rod. The ferro-fluid is supported between the seal and the magnetic conductive material.

Dependencies are inferred from the claim text.