Patent ID: 6946764

Claim:
A spindle motor for use in a disc drive comprising a shaft, the shaft having a first end and a second end that is larger in diameter than the first end, the shaft being disposed within a bore defined by an inner surface of a sleeve supported from a base or a hub, wherein the shaft further comprises a cylindrical portion and a conical portion within the sleeve, the hub being supported for rotation by either the shaft or the sleeve, the shaft and the sleeve being supported for relative rotation by a fluid dynamic journal bearing comprising fluid in a first gap between the shaft and the sleeve, the fluid dynamic journal bearing having asymmetrically proportioned grooves to pump the fluid toward the second end of the shaft, a counterplate having a grooved pattern thereon to maintain fluid in a second gap between the second end of the shaft and the first surface of the counterplate, the grooved pattern supporting the shaft for rotation relative to the counterplate and sleeve and providing a net pumping force inward toward an axial center of the counterplate.