Patent ID: 7306429

Claim:
An axial-flow heat-dissipating fan comprising: an impeller comprising a hub including an outer periphery and a plurality of blades fanned on the outer periphery of the hub and extending in an inclined angle with respect to a longitudinal direction parallel to a rotational axis of the hub, each said blade including a leading edge, a trailing edge, a radial inner edge, and a radial outer edge; and a casing comprising an airflow passage having an air inlet and an air outlet, the casing further comprising a base in the air outlet, a motor being mounted on the base for coupling with and driving the impeller, a plurality of guiding ribs being mounted between an inner periphery of the casing and an outer periphery of the base, each of said guiding ribs including an airflow-encountering line adjacent and tangential to the trailing edge of one of the blades that is closest to said guiding rib; two of the blades adjacent to each other overlapping with each other as viewed from the longitudinal direction such that each said blade has a first overlapped area and a second overlapped area.