Patent ID: 7520674
Filing Date: 2009-04-21
Classification: F16C,G11B

Abstract:
1. A magnetic disk device comprising a magnetic disk that records information, and a drive unit that rotates the magnetic disk about a shaft, wherein: the drive unit comprises a rotary section that holds the magnetic disk, and a stationary section that supports the rotary section through a fluid bearing, the fluid bearing comprises a radial fluid bearing that bears a load in a direction perpendicular to an axial direction, and a thrust fluid bearing that bears a load in the axial direction, and the thrust fluid bearing comprises a first thrust fluid bearing having a diameter and a clearance, and a second thrust fluid bearing positioned outside an outer periphery of the shaft and being larger in diameter and deeper in clearance than the first thrust fluid bearing; wherein the rotary section comprises a shaft that defines a center of rotation, a hub fixed to the shaft to hold the magnetic disk, and a motor rotor that rotates the hub, and the stationary section comprises a sleeve arranged on an outer periphery of the shaft, and a motor stator, the radial fluid bearing is formed between the shaft and the sleeve, and the second thrust fluid bearing is formed between the sleeve and the hub; wherein juxtaposed between an upper surface of the sleeve and a lower surface of the hub are the first thrust fluid bearing on an inner peripheral side of the shaft and the second thrust fluid bearing on an outer peripheral side of the first thrust fluid bearing; wherein the second thrust fluid bearing is formed by an inclined surface inclined so as to become deep in clearance radially outwardly of the first thrust fluid bearing formed on the upper surface of the sleeve.