Abstract: A spindle motor used in a magnetic disc apparatus having a hub to which a magnetic disc is mounted and a rotary shaft to which the hub is fixed. The rotary shaft is located in a bearing casing having one end opened and the other end closed by a hydrodynamic pressure radial bearing, the rotary shaft being supported by a hydrodynamic pressure thrust bearing and the hydrodynamic pressure radial bearing. An inner diameter D and a width L of the hydrodynamic pressure radial bearing having a relationship of L/D<1.

Abstract: A spindle motor used in a magnetic disc apparatus having a hub to which a magnetic disc is mounted and a rotary shaft to which the hub is fixed. The rotary shaft is located in a bearing casing having one end opened and the other end closed by a hydrodynamic pressure radial bearing and hydrodynamic pressure thrust bearing, an inner diameter D and a width L of the hydrodynamic pressure bearing having a relationship of L/D<1.

Abstract: A magnetic disc device includes a magnetic disc and a rotary shaft rotatably supporting the magnetic disc. The magnetic disk is laid in a bearing casing having one end opened, and having a bearing member at the other end. The rotary shaft is supported by a first hydrodynamic fluid bearing and a second hydrodynamic fluid bearing provided in the bearing member. The inner diameter D and the width L of the first hydrodynamic fluid bearing exhibits such a relationship as L/D>1.

Abstract: A rotary shaft is rotatably supported by a hydrodynamic fluid radial bearing and a hydrodynamic fluid thrust bearing which are excellent in shock resistance, an bearing arrangement in which vibration in a translation mode of the shaft, among vibration components caused by unbalance force exerted to the rotary shaft, is supported by the radial bearing, and vibration in conical mode is supported by the thrust bearing, magnetic fluid is used as lubrication oil, and a permanent magnet is located between the radial bearing and the thrust bearing so as to apply a magnetic attracting force between the rotary shaft and the thrust bearing so as to carry out axial positioning in order to use the magnetic disc device in an arbitrary attaching posture.

Abstract: An object of the invention is to provide a method of assembling a disc which can reduce an unbalance of a rotating portion.

Abstract: A magnetic disk device has a large capacity with a small and thin structure and includes a spindle system, an actuator system, a control package for controlling the systems, and a PCMCIA connector. The spindle system is of an in-hub structure wherein two magnetic disks are rotated in inside diameter portions of the magnetic disks. The actuator system has sliders mounting magnetic heads for writing and reading magnetic information to and from the magnetic disks, guide arms and suspension structures. The suspension structures also include a coil, a magnetic circuit for imparting a drive force in cooperation with the coil, a coil holder for supporting the coil, a pivot sleeve for rocking the guide arms, the coil holder and spacers which are integrally laminated to each other, bearings and a pivot shaft. The PCMCIA connector connects to the control package and is fixed by the housing and a package cover.