Fluid Dynamic Pressure Bearing, Spindle Motor Provided with Fluid Dynamic Pressure Bearing, and Recording Disk Drive Device Provided with Spindle Motor

A fluid dynamic pressure bearing comprising:

• a rotor unit rotated coaxially with a rotational center axis and including a rotor hub and a bearing member;
• and
• a stationary unit including a bracket, a shaft fixed to the center of the bracket and an annular member;
• wherein
• the rotor hub has a rotor upper wall fixed to an upper end of the bearing member;
• the annular member is formed by press working and fixed to an upper surface of the bracket and extends upward;
• the bearing member has an inner circumferential surface facing to an outer peripheral surface of the shaft via a first fine clearance, a lower end surface facing to the upper surface of the bracket via a second fine clearance, and an outer peripheral surface facing to an inner circumferential surface of the annular member via a third fine clearance;
• the first, second and third fine clearances are filled with lubricating fluid substantially without interruption;
• and
• the third fine clearance has a capillary seal whose radial clearance width is gradually enlarged upward in an axial direction, and further, the lubricating fluid retained in the third fine clearance defining an interface between air and the same inside of the capillary seal.