Abstract: An ultra-thin spindle motor having a groove formed on the outer circumferential surface of a thrust bearing is disclosed. The present invention relates to an ultra-thin spindle motor among small-sized motor using a hydro dynamic pressure generating bearing and its object is to provide a spindle motor capable of stably driving without requiring a sleeve that was required to support a shaft in a radial direction in which a thrust bearing sleeve for coupling a hub and a thrust bearing is constructed and a radial hydro dynamic pressure generating groove is formed on the outer circumferential surface to thereby allow a radial hydro dynamic pressure to be generated and support a thrust bearing sleeve coupled integrally to the hub.

Abstract: An ultra-thin spindle motor having a groove formed on the outer circumferential surface of a thrust bearing is disclosed. The present invention relates to an ultra-thin spindle motor among small-sized motor using a hydro dynamic pressure generating bearing and its object is to provide a spindle motor capable of stably driving without requiring a sleeve that was required to support a shaft in a radial direction in which a thrust bearing sleeve for coupling a hub and a thrust bearing is constructed and a radial hydro dynamic pressure generating groove is formed on the outer circumferential surface to thereby allow a radial hydro dynamic pressure to be generated and support a thrust bearing sleeve coupled integrally to the hub.

Abstract: A spindle motor having a shaft member secured to a fitting member, a rotary member which is rotatable relatively to the shaft member, a rotor magnet fitted to the rotary member in such a manner that the rotor magnet confronts the rotor magnet and a stator, wherein a pair of inner annular grooves are formed in the shaft member, a pair of outer annular grooves are formed in the rotary member and a plurality of ball members are accommodated in ball-accommodating space defined by these annular grooves.

Abstract: A spindle motor having a shaft member secured to a fitting member, a rotary member which is rotatable relatively to the shaft member, a rotor magnet fitted to the rotary member in such a manner that the rotor magnet confronts the rotor magnet and a stator, wherein a pair of inner annular grooves are formed in the shaft member, a pair of outer annular grooves are formed in the rotary member and a plurality of ball members are accommodated in ball-accommodating space defined by these annular grooves.

Abstract: A magnetic fluid seal assembly comprising an annular sealing clearance communicating with an external space, an annular permanent magnet for forming a magnetic field in the sealing clearance, a ferromagnetic fluid retained in the sealing clearance by the magnetic field but rotationally movable in the sealing clearance, and a scattering preventive portion provided axially outwardly of the sealing clearance for preventing the ferromagnetic fluid from scattering to the external space when the ferromagnetic fluid is rotationally moved.

Abstract: A spindle motor used for example to drive magnetic discs comprises a central shaft and a cylindrical member rotatable relative to the central shaft through a pair of bearings. A small annular clearance is formed between the central shaft and the cylindrical member to communicate with an interior space adjoining one of the bearings. A helical groove is provided at the annular clearance and serves to force any fluid, such as grease vapor, into the interior space.

Abstract: A spindle motor having a shaft member secured to a fitting member, a rotary member which is rotatable relatively to the shaft member, a rotor magnet fitted to the rotary member in such a manner that the rotor magnet confronts the rotor magnet and a stator, wherein a pair of inner annular grooves are formed in the shaft member, a pair of outer annular grooves are formed in the rotary member and a plurality of ball members are accommodated in ball-accommodating space defined by these annular grooves.