Fluid Dynamic Pressure Bearing and Recording Disk Drive Device Comprising the Same

摘要

In a radial minute gap between a substantially columnar shaft and an inner peripheral face of a substantially cylindrical sleeve, oil is retained and a radial dynamic pressure bearing is formed. A plurality of recessed portions are arranged in a circumferential direction on at least one of an outer peripheral face of the shaft and the inner peripheral face of the sleeve and a first hill portion is provided to an axial end portion of each the recessed portion. Thus, it is possible to achieve a dynamic pressure bearing with which sufficient radial shaft support can be obtained in spite of a short axial length.