THRUST DYNAMIC PRESSURE BEARING, SPINDLE MOTOR USING THE BEARING, AND INFORMATION RECORDING/REPRODUCING DEVICE USING THE SPINDLE MOTOR

摘要

A thrust dynamic pressure bearing having a large rigidity to tilting against the swing of a shaft and a small bearing loss torque, a spindle motor using the bearing, and an information recording/reproducing device using the spindle motor. In the thrust dynamic pressure bearing, herring bone grooves (131) having intermediate bent parts (132) are formed in a rotating side bearing surface (11) formed on the rotating side member of the bearing. When the rotating side bearing surface (11) is rotated in a direction (A) (clockwise direction), a lubricating oil causes a dynamic pressure in an area about the intermediate bent parts (132) along the radial outer portions (133) and the radial inner portions (134) of the herring bone grooves (131). Where a relation between the groove width (G) of dynamic pressure generating grooves and the width (L) of ridge parts adjacent to the dynamic pressure generating grooves is G > L at any radius (2) position, the rigidity to the tilting can be increased and the bearing loss torque can be reduced.