Abstract:
An apparatus is used for controlling a rotating direction of a fan. The apparatus comprises a power source, a signaling unit, a switching unit, and an activating module. The power source is used for supplying power for the apparatus. The signaling unit is used for generating direction-control signals. The switching unit is connected to the power source and the signaling unit, and used for controlling the switching unit to work. The activating module is connected to the switching unit and the fan, and used for driving the fan to selectively rotate in one of two opposite directions based on the direction-control signals. A method for driving the fan in the two directions is also disclosed.

Description:
1. FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to apparatuses and methods for controlling fans, and more particularly to an apparatus and a method for controlling rotational directions of a fan. 
       2. DESCRIPTION OF RELATED ART 
       [0002]    Nowadays, some electronic devices generate much heat when working. Such heat can adversely affect the operational stability of the electronic devices. Concretely, an accumulation of the heat in the electronic devices will lead to a temperature increase of the electronic devices, thus resulting in an unstable operation and even a destruction of the electronic devices. Therefore, the heat must be removed in time to keep the temperature of the electronic devices within a safe range. Fans have been used in the electronic devices for providing forced airflows to dissipate the heat. 
         [0003]    However, large amount of debris such as dust, dirt, trash, and the like is doped in the airflows. The debris enters the electronic devices following the airflows, and lodges in the electronic devices. Accumulation of the debris baffles the cooling operations of the airflows. 
         [0004]    A bi-directional fan has been used in the electronic devices for dislodging the debris. The fan can selectively rotate in a clockwise direction or an anti-clockwise direction. When rotating in the clockwise direction, the fan drives the airflow through the electronic device and takes the heat away. When rotating in the anti-clockwise direction, the fan dislodges the debris out of the electronic devices. 
         [0005]    A conventional apparatus is used for controlling the fan to change its rotating direction by using a switch to change polarities of two electrodes of the fan. Thus, the fan can change its rotating direction as the polarities of the electrodes of the fan are changed. 
         [0006]    However, the conventional apparatus cannot work automatically. Users need to manually operate the switch to change the rotating direction of the fan. 
         [0007]    Therefore, an apparatus and a method for a fan are needed in the industry to address the aforementioned deficiencies and inadequacies. 
       SUMMARY OF THE INVENTION 
       [0008]    An apparatus is used for controlling a rotating direction of a fan. The apparatus comprises a power source, a signaling unit, a switching unit, and an activating module. The power source is used for supplying power for the apparatus. The signaling unit is used for generating direction-control signals. The switching unit is connected to the power source and the signaling unit, and used for controlling the switching unit to work. The activating module is connected to the switching unit and the fan, and used for driving the fan to selectively rotate in one of two opposite directions based on the direction-control signals. A method for driving the fan in the two directions is also disclosed. 
         [0009]    Other systems, methods, features, and advantages of the present apparatus and method will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present device, and be protected by the accompanying claims. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Many aspects of the present apparatus and the present method can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0011]      FIG. 1  is a block diagram showing a fan and an apparatus in accordance with an exemplary embodiment, the apparatus including a controlling module; 
           [0012]      FIG. 2  is a block diagram showing a detailed structure of the controlling module of  FIG. 1  in accordance with a first embodiment; 
           [0013]      FIG. 3  is a block diagram showing a detailed structure of the controlling module of  FIG. 1  in accordance with a second embodiment; 
           [0014]      FIG. 4  is a process flow diagram of how a method is implemented in accordance with an exemplary embodiment; and 
           [0015]      FIG. 5  is a block diagram illustrating a processor comprising a computer program in accordance with an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Reference will now be made to the drawings to describe a preferred embodiment of the present apparatus and a preferred embodiment of the present method. 
         [0017]    Referring to  FIG. 1 , an apparatus  200  is connected between an electronic device  100  and a fan  300 . The fan  300  is able to rotate in either a clockwise direction or an anti-clockwise direction. The electronic device  100  may be a computer, a television, a projector, or the like. In this embodiment, the electronic device  100  is a computer. The electronic device  100  is used for sending control signals to the apparatus  200 . The apparatus  200  receives the control signals and controls rotational directions of the fan  300  based on the control signals. 
         [0018]    The electronic device  100  includes a power source A  110  and a signal source  120 . The power source A  110  is used for supplying power to the signal source  120 . The signal source  120  is used for generating the control signals, and sending the control signals to the apparatus  200 . When the power source A  110  is turned on, the signal source  120  generates a low level voltage signal. When the power source A  110  is turned off, the signal source  120  generates a high level voltage signal. 
         [0019]    The apparatus  200  includes a controlling module  210 , an activating module  220 , a power source B  230 , and a time delay module  240 . The controlling module  210  is connected to the signal source  120 , the activating module  220 , and the power source B  230 . The activating module  220  is connected to the controlling module  210 , the power source B  230 , and the fan  300 . The power source B  230  is used for supplying power to the controlling module  210  and the activating module  220 . In this embodiment, the power source B  230  supplies a voltage of 12 volts. The time delay module  240  is connected to the signal source  120  and the power source B  230 . 
         [0020]    When the signal source  120  sends the low level voltage signal to the controlling module  210 , the controlling module  210  generates and sends a positive signal to the activating module  220 . The activating module  220  receives the positive signal and drives the fan  300  to rotate in the clockwise direction. The time delay module  240  is not activated. 
         [0021]    On the other hand, when the signal source  120  sends the high level voltage signal to the controlling module  210 , the controlling module  210  generates and sends a negative signal to the activating module  220 . The activating module  220  receives the negative signal and drives the fan  300  to rotate in the anti-clockwise direction. The time delay module  240  also receives the high level voltage signal, and becomes activated. When a predetermined delay time specified in the time delay module  240  have elapsed, the fan  300  stops rotating. 
         [0022]    Therefore, when the electronic device  100  is powered on, the apparatus  200  drives the fan  300  to rotate in the clockwise direction. When the electronic device  100  is powered off, the apparatus  200  drives the fan  300  to rotate in the anti-clockwise direction. 
         [0023]    Referring to  FIG. 2 , the activating module  220  in accordance with a first embodiment has a first input terminal  271 , a second input terminal  272 , a first output terminal  273 , and a second output terminal  274 . The first output terminal  273  and the second output terminal  274  output a driving voltage to drive the fan  300  to rotate. 
         [0024]    When the first input terminal  271  receives a high level voltage signal, and the second input terminal  272  receives a low level voltage signal, wherein the two signals combine to form the positive signal, the driving voltage outputted from the first output terminal  273  and the second output terminal  274  drives the fan  300  to rotate in the clockwise direction. 
         [0025]    When the first input terminal  271  receives a low level voltage signal, the second input terminal  272  receives a high level voltage signal, wherein the two signals combine to form the negative signal, the driving voltage drives the fan  300  to rotate in the anti-clockwise direction. 
         [0026]    The controlling module  210  has a first node  211  and a second node  213 . An input terminal  261  of a trigger A  212  is connected to the first node  211 . An output terminal  262  of the trigger A  212  is connected to the first input terminal  271  of the activating module  220 , and further connected to the second input terminal  272  via a negation gate  281 . A resistor R 1  is connected between the first node  211  and the power source B  230 . An input terminal  263  of a trigger B  214  is connected to the second node  213 . An output terminal  264  of the trigger B  214  is connected to the first input terminal  271  of the activating module  220  via a negation gate  282  and further connected to the second input terminal  272 . A resistor R 2  is connected between the second node  213  and the power source B  230 . The power source B  230  is used for supplying power to the trigger A  212  and the trigger B  214 . 
         [0027]    A first bipolar junction transistor (BJT)  216  is used as a switch for controlling the power from the power source B  230  receivable by the trigger A  212 . A collector of the first BJT  216  is connected to the first node  211 . An emitter of the first BJT  216  is connected to a first virtual ground point. A base of the first BJT  216  is connected to the signal source  120  via a resistor R 3 . A second BJT  218  is used as a switch for controlling the power from the power source B  230  receivable by the trigger B  214 . A collector of the second BJT  218  is connected to the second node  213 . An emitter of the second BJT  218  is connected to a second virtual ground point. A base of the second BJT  218  is connected to the first node  211  via a resistor R 4 . 
         [0028]    When the base of the first BJT  216  receives the low level voltage signal, the first BJT  216  is disabled. The first node  211  connected to the power source B  230  is at a high level voltage. That is, the trigger A  212  is powered on, and the trigger A  212  generates the positive signal that is further sent to the activating module  220 . The high level voltage at the first node  211  enables the second BJT  218 , and the power transmitted from the power source B  230  to the second node  213  is directed to the second virtual ground point. Therefore, power from the power source B 230  to the trigger B  214  is discontinued by a short circuit established between the power source B  230  and the second virtual ground point. 
         [0029]    When the base of the first BJT  216  receives the high level voltage signal, the high level voltage enables the first BJT  216 . The power transmitted to the first node  211  is directed to the first virtual ground point. The trigger A  212  is discontinued by a short circuit established between the power source B  230  and the first virtual ground point. The second BJT  218  is disabled, and the second node  213  connected to the power source B  230  is at a high level voltage. That is, the trigger B  214  is powered on by the power source B  230 . The trigger B  214  generates the negative signal and sends the negative signal to the activating module  220 . 
         [0030]    In a second embodiment, the first BJT  216  and the second BJT  218  may be replaced with FETs. Referring to  FIG. 3 , a first field effect transistor (FET)  216 ′ is used to replace the first BJT  216 , and a second FET  218 ′ is used to replace the second BJT  218 . Similarly, in a controlling module  210 ′, a drain of the first FET  216 ′ is connected to the first node  211 . A source of the first FET  216 ′ is connected to a first virtual ground point. A gate of the first FET  216 ′ is connected to the signal source  120  via a resistor R 3 . A drain of the second FET  218 ′ is connected to the second node  213 . A source of the second FET  218 ′ is connected to a second virtual ground point. A gate of the second FET  218 ′ is connected to the first node  211  via a resistor R 4 . 
         [0031]    As known, a BJT and a FET are both transistors. The poles of the BJT and the FET can be redefined based on their function. The base and the gate can be identified as an operating pole of the transistor; the emitter and the source can be identified as a grounding pole of the transistor; the collector and the drain can be identified as a controlling pole of the transistor. 
         [0032]    The apparatus  200  can control the fan  300  to switch the rotating direction between a clockwise direction and an anti-clockwise direction automatically based on control signals from the electronic device  100 . Therefore, not only can the fan  300  dissipate the heat of the electronic device  100  but can also dislodge the debris in the electronic device  100 . 
         [0033]    Referring to  FIG. 4 , a process flow diagram in accordance with an exemplary embodiment illustrates a procedure of a method for driving the fan  300  to rotate bidirectionally. The procedure includes the following steps. 
         [0034]    The power source A  110  is turned on and supplies power to the signal source  120  (step  902 ). 
         [0035]    The signal source  120  generates the low level voltage signal that is further sent to an operating pole of a first transistor (step  904 ). 
         [0036]    The first transistor is disabled and a second transistor becomes enabled, with the first node  211  being at the high level voltage, and the second node  213  being at the low level voltage (step  906 ). 
         [0037]    The trigger A  212  is powered on, and the trigger B  214  is powered off (step  908 ). 
         [0038]    The trigger A  212  generates the positive signal that is further sent to the activating module  220  (step  910 ). 
         [0039]    The activating module  220  drives the fan  300  to rotate in the clockwise direction (step  912 ). 
         [0040]    The power source A  110  is turned off (step  914 ). 
         [0041]    The signal source  120  generates the high level voltage signal that is further sent to the operating pole of the first transistor (step  916 ). 
         [0042]    The first transistor becomes enabled and the second transistor becomes disabled, with the first node  211  being at the low level voltage, and the second node  213  being at the high level voltage (step  918 ). 
         [0043]    The trigger A  212  is powered off, and the trigger B  214  is powered on (step  920 ). 
         [0044]    The trigger B  214  generates the negative signal that is further sent to the activating module  220  (step  922 ). 
         [0045]    The activating module  220  drives the fan  300  to rotate in the anti-clockwise direction (step  924 ). 
         [0046]    Referring to  FIG. 5 , it is further noted that all functions aforementioned above can be performed by a processor  400  having some functional computer codes. The processor  400  includes a computer program  410 . The computer program  410  includes power supplying codes  411 , low level voltage signal generating codes  412 , positive signal generating codes  413 , power supply stopping codes  414 , high level voltage signal generating codes  415 , and negative generating codes  416 . The power supplying codes  411  and the power supply stopping codes  414  have similar functions to those of the power source A  110 . The low level voltage signal generating codes  412  and the high level voltage signal generating codes  415  have similar functions to those of the signal source  120 . The positive signal generating codes  413  and the negative generating codes  416  have similar functions to those of the controlling module  210 . 
         [0047]    It should be emphasized that the above-described preferred embodiment, is merely a possible example of implementation of the principles of the invention, and is merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and be protected by the following claims.