Fluid dynamic pressure bearing and motor and magnetic disk apparatus using fluid dynamic pressure bearing

DETAILED DESCRIPTION The present invention has been made in view of the fact described above and it is an object of the present invention to provide a fluid dynamic pressure bearing which is capable of reserving sufficient lubricating oil, increasing the allowable tolerance for lubricating oil charging volume and assuring use over a long period of time.
Another object of the present invention is to provide a fluid dynamic pressure bearing which is capable of checking or supplying lubricating oil from the outside of an equipment which adopted this type of dynamic pressure bearing without disassembling the equipment when it is operated over a long period of time and a motor and a disk driving apparatus using this type of bearing.
It is another object of this invention to provide a hydrodynamic bearing capable of preventing or reducing leakage of an lubricating oil to outside.
According to the present invention, in a fluid dynamic pressure bearing comprising a shaft member and a sleeve member which is relatively rotatable to the shaft member, thrust fluid dynamic pressure bearing means and radial fluid dynamic pressure bearing means provided between the shaft member and the sleeve member, and lubricating fluid in the thrust and radial fluid dynamic pressure bearing means are communicated each other, a lubricating fluid retaining channel is provided to retain lubricating fluid and has a space larger than a space between the thrust and radial fluid dynamic pressure bearing means but sufficiently small to retain lubricating fluid by the capillarity and at least a part of this retaining channel is open to the atmosphere and its other part is communicated with the thrust and/or radial fluid dynamic bearing means and a disk driving apparatus adopting this fluid dynamic pressure bearing are provided.
Further, according to the present invention, in a motor comprising a mounting member, a sleeve member fixed to the mounting member, a stator fixed to the sleeve member, a shaft member which is supported rotatably by thrust fluid dynamic pressure bearing means and radial fluid dynamic bearing means, a rotor mounted to the shaft member and a rotor magnet mounted to the rotor, a retaining channel for retaining lubricating fluid by the capillarity is provided to the shaft member, a part of the retaining channel is open to the atmosphere and the other part is communicated with the thrust and/or radial fluid dynamic bearing means