System and method for control of fan rotational speed

Abstract

A system and a method for control of fan rotational speed are applied in an electronic device with a fan for temperature adjustment. The electronic device at least records a first fan rotational speed of the fan when a temperature of the fan is higher than a predetermined temperature interval and a second fan rotational speed of the fan when the temperature of the fan is lower than the temperature interval. A fan rotational speed during operation of the fan is recorded. The electronic device detects a temperature of an exothermic object being adjusted by the fan, and outputs a temperature parameter. The electronic device determines whether the temperature parameter belongs to the temperature interval and accordingly adjusts the fan rotational speed of the fan. The system and method make change of the fan rotational speed less sensitive to oscillations in system temperature and prolong the lifetime of the fan.

1 . A system for control of fan rotational speed of a fan in an electronic device for temperature adjustment, comprising: 
 a temperature interval recording module for at least recording a first fan rotational speed of the fan when a temperature of the fan is higher than a predetermined temperature interval and a second fan rotational speed of the fan when the temperature of the fan is lower than the predetermined temperature interval;    a rotational speed recording module for recording a fan rotational speed of the fan during operation of the fan;    a temperature detecting module for detecting a temperature of an exothermic object being adjusted by the fan and outputting a temperature parameter; and    a determining module for determining whether the temperature parameter output by the temperature detecting module belongs to the temperature interval recorded by the temperature interval recording module, if yes, allowing the fan to operate at the same fan rotational speed, or if no, according to the temperature parameter determining from the temperature interval recording module whether a fan rotational speed corresponding to the temperature parameter is the same as the fan rotational speed recorded by the rotational speed recording module; if the fan rotational speeds are different, according to the temperature parameter determining from the temperature interval recording module whether the temperature parameter is lower than the temperature interval; if the temperature parameter is lower than the temperature interval, reducing the fan rotational speed of the fan and updating the fan rotational speed recorded by the rotational speed recording module with the reduced fan rotational speed, or if the temperature parameter is not lower than the temperature interval, allowing the fan to operate at the fan rotational speed recorded by the rotational speed recording module; or if the fan rotational speeds are the same, according to the temperature parameter determining from the temperature interval recording module whether the temperature parameter is higher than the temperature interval; if the temperature parameter is higher than the temperature interval, increasing the fan rotational speed of the fan and updating the fan rotational speed recorded by the rotational speed recording module with the increased fan rotational speed, or if the temperature parameter is not higher than the temperature interval, allowing the fan to operate at the fan rotational speed recorded by the rotational speed recording module.    
   
   
       2 . The system as claimed in  claim 1 , wherein the temperature interval recorded by the temperature interval recording module is formed by a critical temperature value and a small temperature difference from the critical temperature value.  
   
   
       3 . The system as claimed in  claim 2 , wherein the critical temperature value serves as an upper limit of the temperature interval, and a lower limit of the temperature interval corresponds to a value of the critical temperature value minus the small temperature difference.  
   
   
       4 . The system as claimed in  claim 1 , wherein the first rotational speed is greater than the second rotational speed.  
   
   
       5 . The system as claimed in  claim 1 , wherein the temperature interval recording module is further for recording a plurality of temperature intervals corresponding to different fan rotational speeds.  
   
   
       6 . A method for control of fan rotational speed of a fan in an electronic device for temperature adjustment, comprising the steps of: 
 having the electronic device at least record a first fan rotational speed of the fan when a temperature of the fan is higher than a predetermined temperature interval and a second fan rotational speed of the fan when the temperature of the fan is lower than the predetermined temperature interval, and record a fan rotational speed during operation of the fan;    having the electronic device detect a temperature of an exothermic object being adjusted by the fan and output a temperature parameter;    having the electronic device determine whether the output temperature parameter belongs to the recorded temperature interval, if yes, allowing the fan to operate at the same fan rotational speed, or if no, according to the temperature parameter determining whether a fan rotational speed corresponding to the temperature parameter is the same as the recorded fan rotational speed during operation of the fan; if the fan rotational speeds are different, according to the temperature parameter determining whether the temperature parameter is lower than the temperature interval; if the temperature parameter is lower than the temperature interval, reducing the fan rotational speed of the fan and updating the fan rotational speed recorded in the electronic device with the reduced fan rotational speed, or if the temperature parameter is not lower than the temperature interval, allowing the fan to operate at the fan rotational speed recorded in the electronic device; if the fan rotational speeds are the same, according to the temperature parameter determining whether the temperature parameter is higher than the temperature interval; if the temperature parameter is higher than the temperature interval, increasing the fan rotational speed of the fan and updating the fan rotational speed recorded in the electronic device with the increased fan rotational speed, or if the temperature parameter is not higher than the temperature interval, allowing the fan to operate at the fan rotational speed recorded in the electronic device.    
   
   
       7 . The method as claimed in  claim 6 , wherein the temperature interval recorded by the electronic device is formed by a critical temperature value and a small temperature difference from the critical temperature value.  
   
   
       8 . The method as claimed in  claim 7 , wherein the critical temperature value serves as an upper limit of the temperature interval, and a lower limit of the temperature interval corresponds to a value of the critical temperature value minus the small temperature difference.  
   
   
       9 . The method as claimed in  claim 6 , wherein the first rotational speed is greater than the second rotational speed.  
   
   
       10 . The method as claimed in  claim 6 , wherein the electronic device further records a plurality of temperature intervals corresponding to different fan rotational speeds.