Low-profile spindle motor whose entire shaft length is utilized to configure,
along an encompassing sleeve, a radial dynamic-pressure bearing section. One end
of the shaft is unitary with the rotor, and a cover member closes the other end.
Between the sleeve upper-end face and the rotor undersurface a thrust bearing section
is configured. Micro-gaps are formed continuing between the sleeve upper-end face
and the rotor undersurface; the sleeve inner-circumferential surface and the shaft
outer-circumferential surface; and the cover member inner face and the shaft end
face, where an axial support section is established. Oil continuously fills the
micro-gaps, configuring a full-fill hydrodynamic bearing structure. Hydrodynamic
pressure-generating grooves in the radial bearing section are configured either
so that no axial flow, or so that a unidirectional flow that recirculates from
one to the other axial end of the radial bearing section through a communicating
pathway is induced in the oil.
