Patent ID: 8502491

Claim:
A rotation direction control method of a cooling fan executed in a predetermined cooling time period and a predetermined dust-expelling time period immediately following the predetermined cooling time period, wherein the cooling fan comprises a motor that is driven by a cooling signal to perform a cooling operation in the predetermined cooling time period, comprising: a detection step receiving a temperature control signal from a temperature detection unit by a rotation direction control unit when the predetermined dust-expelling time period begins; a determination step determining whether a detected temperature is higher than a predetermined value based on the temperature control signal by the rotation direction control unit; and a driving step controlling the rotation direction control unit to keep outputting the cooling signal to drive the motor of the cooling fan for the cooling operation when the determination of the determination step is positive, wherein the driving step controls the rotation direction control unit to output a dust-expelling signal to drive the motor of the cooling fan for a dust exhaustion operation when the determination of the determination step is negative; wherein an adjusting switch has an input end, an output end, a control end, a first electronic switch and a second electronic switch, the input end is electrically coupled to a rotation direction switching device, the output end is electrically coupled to a driving unit, the control end is electrically coupled to the temperature detection unit, the first and second electronic switches are electrically coupled in series between the input end and a power supply, the output end is where the first and second electronic switches are electrically coupled together, and controlled ends of the first and second electronic switches jointly form the control end.