Fan

Abstract

A fan includes an interface connected to a motherboard, a fan motor, a battery, a switch connected to the battery, and a controller connected to the interface, the fan motor, the switch, and the battery. The controller includes a storage unit to store a preset timing value, a timer to count a working time of the fan motor after the motherboard is powered off, and a control unit. When the motherboard is powered on, the control unit receives a voltage from the motherboard and outputs the voltage to the fan motor. When the motherboard is powered off, the control unit controls the switch to be turned on. The battery provides a voltage to the fan motor. The control unit controls the switch to be turned off when a working time of the fan motor reaches the preset timing value.

What is claimed is: 
     
         1 . A fan comprising:
 an interface connected to a motherboard;   a fan motor;   a battery;   a switch connected to the battery; and   a controller connected to the interface, the fan motor, the switch, and the battery, the controller comprising:
 a storage unit to store a preset timing value; 
 a timer to count timing of the fan motor after the motherboard being powered off; and 
 a control unit; 
 wherein when the motherboard is powered on, the control unit receives a voltage from the motherboard through the interface, and outputs the received voltage to the fan motor, to control the fan motor to operate; when the motherboard is powered off, the control unit controls the switch to be turned on, the battery provides a voltage to the fan motor through the switch and the controller, to control the fan motor to operate, the timer counts a working time of the fan motor, the control unit controls the switch to be turned off when the working time of the fan motor reaches the preset timing value, to prevent the battery from providing the voltage to the fan motor. 
   
     
     
         2 . The fan of  claim 1 , wherein the battery is a rechargeable battery. 
     
     
         3 . The fan of  claim 2 , wherein the controller further comprises a charging unit, the storage unit further stores a saturation voltage of the rechargeable battery, the control unit measures a voltage of the rechargeable battery and compares the measured voltage with the saturation voltage value stored in the storage unit, the control unit controls the switch to be turned on in response to the measured voltage of the rechargeable battery being less than the saturation voltage value, the charging unit charges the rechargeable battery; the control unit controls the switch to be turned off in response to the measured voltage of the rechargeable battery being equal to the saturation voltage value, to prevent the charging unit from charging the rechargeable battery.