Patent ID: 8382427

Claim:
A blower fan comprising: a housing having an air outlet and a cover plate providing a first air inlet and formed on a top of the housing, with the first air inlet and the air outlet being communicated with a compartment of the housing; a stator being mounted in the compartment; and an impeller being mounted in the compartment, with the impeller having a hub and a plurality of vanes coupled to the hub, and with each vane having an upper edge, wherein, for each vane, an end of the upper edge is an air input portion adjacent to the first air inlet of the cover plate, and an air gap is formed between the upper edges of the vanes and the top of the housing, with various widths of the air gap ranging from 0.3 mm to 2.0 mm while a shortest width of the air gap is formed between the air input portion of the upper edge and the cover plate of the housing.