Fluid dynamic pressure bearing, motor, and recording medium driving device

A fluid dynamic pressure bearing comprising, a shaft having a substantially cylindrical shaft body, and a substantially cylindrical housing which has a shaft body insertion hole for accommodating the shaft body rotatably,

• and on an outer peripheral surface of the housing is provided a flange shaped thrust bearing plate that extends in the radial outward direction all around the periphery, and on the shaft is provided a thrust bearing plate which faces an end face in the thickness direction of the thrust bearing plate via a gap, and
• there is provided an annular dynamic pressure generating face made by forming a dynamic pressure generating groove, which draws a working fluid toward a midway position in the radial direction from the inside and outside of the thrust bearing plate in the radial direction, or toward a position near an outer peripheral rim from the inside in the radial direction, when the shaft and the housing are rotated relative to each other about the axis, on the thickness direction end face of the thrust bearing plate or on an inner surface of the housing facing the end face via a gap, and an inner groove section, which is located on an inner peripheral side of the dynamic pressure generating face and that is depressed more than the dynamic pressure generating face in the thickness direction, and
• there is provided a through hole which passes through the thrust bearing plate in the thickness direction so as to open to the dynamic pressure generating face, and there is provided a communicating cavity which connects the opening portion of the through hole and the inner groove section.