Abstract: An axial flow fan. The axial flow fan includes an impeller, an annular structure, and a plurality of connecting portions. The impeller has a plurality of blades, arranged radially. Each blade has an outer periphery. The outer periphery has a top portion. The annular structure is attached to the top portion of the outer periphery of each blade. Each connecting portion respectively connects each blade to the annular structure.

Abstract: A fan assembly and impeller thereof. The fan assembly includes a plurality of blades and a hub. The hub includes an upper surface and a center point. The blades have bottom portions arranged in a circle on the upper surface with respect to the center point.

Abstract: A fan motor speed control circuit includes a driving circuit, a voltage division circuit, and a speed modulator. The voltage division circuit has a first transistor and a plurality of resistors and is connected between a voltage source and the driving circuit. The speed modulator has a second transistor and a plurality of parallel resistors and is connected between the voltage division circuit and the driving circuit. The current of the fan motor speed control circuit flows through a first path under a first input voltage generated from the voltage source and through a second path under a second input voltage larger than the first one; the parallel resistors are in the second path such that the current value passing through the driving circuit varies according to the resulting resistance value of the parallel resistors.

Abstract: A heat-dissipating device and a housing thereof. The housing includes a passage for guiding an air stream flowing from an opening to another opening, wherein an inner wall of the passage at at least one of the opening sides extends radially outwards with a rotational axis of the heat-dissipating device or the passage so as to enlarge intake or discharge area for the air streams. Accordingly, the intake airflow rate may be greatly increased and the heat-dissipating efficiency of the heat-dissipating device may be greatly enhanced without changing assembling conditions with other elements.

Abstract: A composite heat-dissipating device is provided for significantly increasing the number and size of blades so as to enhance the heat-dissipating performance. The composite heat-dissipating device is constructed by a plurality of impellers, each of which includes a plurality of blades. When the plurality of impellers are assembled together, the plurality of blades are arranged around the hub of the composite heat-dissipating device and there is an overlapped region formed between every two adjacent blades.

Abstract: A heat-dissipating module includes a heat sink and a fan device. The fan device may be disposed on the heat sink, or inserted into the heat sink to reduce the height. The fan device includes a first rotor blade and a second rotor blade. The first rotor blade and the second rotor blade are connected in series. The rotation speed of the first rotor blade is controlled by a first control circuit, and the second rotor blade is controlled by the second circuit. Thus, the second control circuit increases the rotation speed of the second rotor blades when the first rotor blades is failed.

Abstract: A cooling fan with high heat-dissipating performance includes a plurality of blades; and a frame for receiving the blades therein, wherein the frame has a reduced height for exposing the blades to outside of the frame so as to allow air to enter into the frame via a top portion and a peripheral portion of the blades to improve air introduction and heat dissipating efficiency of the cooling fan. A cover may be mounted to a top surface of the frame, and formed with a plurality of openings for allowing air to enter into the frame through the openings; such an arrangement cam effectively enhance air intake and working efficiency of the cooling fan.

Abstract: A composite heat-dissipating device is provided for significantly increasing the number and size of blades so as to enhance the heat-dissipating performance. The composite heat-dissipating device is constructed by a plurality of impellers, each of which includes a plurality of blades. When the plurality of impellers are assembled together, the plurality of blades are arranged around the hub of the composite heat-dissipating device and there is an overlapped region formed between every two adjacent blades.

Abstract: A heat-dissipating module includes a heat sink and a fan device. The fan device may be disposed on the heat sink, or inserted into the heat sink to reduce the height. The fan device includes a first rotor blade and a second rotor blade. The first rotor blade and the second rotor blade are connected in series. The rotation speed of the first rotor blade is controlled by a first control circuit, and the second rotor blade is controlled by the second circuit. Thus, the second control circuit increases the rotation speed of the second rotor blades when the first rotor blades is failed.

Abstract: An embedded centrifugal cooling device is disclosed. The embedded centrifugal cooling device includes a heat sink and a centrifugal fan. The heat sin includes a plurality of cooling fins defining a cavity. The centrifugal fan is formed in the cavity so as to be embedded into the heat sink. The present invention further includes a cover formed on the heat sink and the centrifugal fan to keep airtight substantially.