Abstract:
An embedded controller outputs a predefined initiation signal to initiate a heat dissipating fan. If the temperature of the CPU does not have a predetermined drop, the embedded controller will output a pulse width modulated (PWM) signal that is different from the preceding initiation signal to start the heat dissipating fan and overcome a phase death angle problem

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a notebook, and more specifically to a method for initiating a heat dissipating fan in a notebook.  
           [0003]    2. Description of the Prior Art  
           [0004]    In a notebook, a controller can output a direct current (DC) initiation signal to initiate a dissipating fan. When initiating the dissipating fan, a phase exists between an axle of the dissipating fan and a magnet, so causing the axle of the dissipating fan to be oriented at a magnetic phase death angle. Thus, the DC initiation signal output to the dissipating fan is not capable of initiating the dissipating fan.  
           [0005]    Please refer to FIG. 1 of a functional block diagram of a prior art computer system  100 . The computer system  100  comprises a central processing unit (CPU)  10 , a heat dissipating fan  12  for dissipating heat generated by the CPU  10 , and a controller  16  electrically connected to the CPU  10  and the heat dissipating fan  12  for controlling rotations of the heat dissipating fan  12 .  
           [0006]    As shown in FIG. 1, when the computer system  100  is initiated and the CPU  10  starts to operate, the controller  16  is capable of outputting a direct current (DC) initiation signal to initiate a dissipating fan  12  for dissipating heat generated by the CPU  10 . The DC initiation signal output to the dissipating fan  12  is not capable of initiating the dissipating fan  12  because of the magnetic phase death angle.  
           [0007]    For this reason, the present invention provides a method for initiating a heat dissipating fan in a computer system to solve the above mentioned problems.  
         SUMMARY OF THE INVENTION  
         [0008]    It is therefore a primary objective of this invention to provide a method for initiating a heat dissipating fan in a computer system.  
           [0009]    According to the claimed invention, a computer system comprises a central processing unit (CPU), a temperature sensor for detecting the temperature of the CPU, a heat dissipating fan for dissipating heat generated by the CPU, and an embedded controller electrically connected to the temperature sensor and the heat dissipating fan for controlling rotations of the heat dissipating fan. The method is performed by using the embedded controller to output a predefined initiation signal to initiate the heat dissipating fan. If the temperature of the CPU continually increases and does not decrease below a predetermined temperature within a predetermined time period, the embedded controller will output a pulse width modulated (PWM) signal that is different from the preceding initiation signal to start the heat dissipating fan.  
           [0010]    It is an advantage of the present invention that the computer system uses the embedded controller to output the pulse width modulated (PWM) signal that is different from the preceding initiation signal to start the heat dissipating fan. Therefore, the computer does not experience the problems that occur due to a magnetic phase death angle.  
           [0011]    These and other objectives and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a functional block diagram of a prior art computer system.  
         [0013]    [0013]FIG. 2 is a functional block diagram of a first preferred embodiment of the present computer system.  
         [0014]    [0014]FIG. 3 is a functional block diagram of a second preferred embodiment of the present computer system. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    Please refer to FIG. 2 of a functional block diagram of a first preferred embodiment of the present computer system  100 . The computer system  100  is a notebook comprising a central processing unit (CPU)  20 , a dissipating fan  22 , an embedded controller  26 , and a temperature sensor  28 .  
         [0016]    The temperature sensor  28  of the computer system  100  is located within the CPU  20  or the embedded controller  26  for detecting the temperature of the CPU  20 . The heat dissipating fan  22  is electrically connected to the embedded controller  26  for dissipating heat generated by the CPU  20 . The embedded controller  26  is electrically connected to the temperature sensor  28  and the heat dissipating fan  22  for controlling a keyboard  30  of the computer system  100  and rotations of the heat dissipating fan  22  manipulated by an output of the temperature sensor  28 .  
         [0017]    When the computer system  100  is switched on or the temperature sensor  28  detects that the temperature of the CPU  20  exceeds a predetermined temperature, the CPU  20  will use the embedded controller  26  to initiate the heat dissipating fan  22  by use of a method described below.  
         [0018]    The method for initiating a heat dissipating fan  22  of the computer system  100  comprises the following steps:  
         [0019]    1. To use the embedded controller  26  to output a predetermined initiation signal to initiate the heat dissipating fan  26 , with the predetermined initiation signal being a direct current (DC) signal or a pulse width modulation (PWM) signal.  
         [0020]    2. If the temperature sensor  28  detects that the CPU  20  does not continually increases and does not decrease below a certain temperature within a predetermined time period, the embedded controller  26  will output a PWM signal, that is different from a previous initiation signal to initiate the heat dissipating fan  22 .  
         [0021]    3. Repeating step  2  until the CPU  20  achieves the predetermined temperature difference or the heat dissipating fan  22  cannot be initiated for a predetermined period of time.  
         [0022]    An advantage of this method is when the CPU  20  does not reach a predetermined temperature decrease within a predetermined time period, the embedded controller  26  will output the PWM signal which is different from a previous initiation signal to initiate the heat dissipating fan  22 . This method enables the heat dissipating fan  22  to escape a magnetic phase death angle.  
         [0023]    Please refer to FIG. 3 of a functional block diagram of a second preferred embodiment of the present computer system  200 . The difference between the method employed in the computer  200  and employed in the computer  100 , is that the heat dissipating fan  22  of the computer  200  further comprises a power input end  40  and a feedback end  42 . The embedded controller  26  is electrically connected to the power input end  40  and the feedback end  42  of the heat dissipating fan  22 .  
         [0024]    When the computer system  200  is switched on or the temperature sensor  28  detects that the temperature of the CPU  20  exceeds a predetermined temperature, the CPU  20  will use the embedded controller  26  to initiate the heat dissipating fan  22  by using the method described below.  
         [0025]    The method for initiating the heat dissipating fan  22  of the computer system  200  comprises the following steps:  
         [0026]    1. To use the embedded controller  26  to output a predetermined initiation signal to initiate the heat dissipating fan  26 , and the predetermined initiation signal is a DC signal or a PWM signal.  
         [0027]    2. If the embedded controller  26  cannot detect that the heat dissipating fan  22  has been initiated from the feedback end  42  within a predetermined time period, the embedded controller  26  will output a PWM signal which is different from a previous initiation signal to initiate the heat dissipating fan  22 .  
         [0028]    3. Repeating step  2  until the heat dissipating fan  22  is initiated or the heat dissipating fan  22  cannot be initiated for a predetermined period of time.  
         [0029]    An advantage of the first embodiment method is when the embedded controller  26  cannot detect that the heat dissipating fan  22  has been initiated from the feedback end  42 , the embedded controller  26  will output the PWM signal which is different from a previous initiation signal to initiate the heat dissipating fan  22 . In this situation, the heat dissipating fan  22  is able to escape the magnetic phase death angle.  
         [0030]    In contrast to the prior art, when the heat dissipating fan  22  of the present computer system  100 ,  200  cannot be initiated, the embedded controller  26  will continuously output the PWM signal which is different from a previous initiation signal to initiate the heat dissipating fan  22 . For this reason, the computer systems  100 ,  200  do not experience the problem of magnetic phase death angle resulting in the dissipating fan  22  not being initiated.  
         [0031]    The above disclosure is not intended as limiting. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.