Patent Publication Number: US-2015059358-A1

Title: Controlling method for thermoelectric cooling device and heat-dissipating module employing same

Description:
FIELD OF THE INVENTION  
     The present invention relates to a controlling method, and more particularly to a controlling method for a thermoelectric cooling device and a heat-dissipating module employing the same. 
     BACKGROUND OF THE INVENTION  
     Recently, with increasing development of industrial technologies and science, a variety of electronic devices are gradually improved, so that the functions and the processing speeds of these electronic devices are enhanced. Consequently, the electronic components within these electronic devices must have high power or high integration level. During operation of the electronic devices, the electronic components may generate energy in the form of heat. If no proper heat-dissipating mechanism is provided to transfer enough heat to the ambient air, the elevated operating temperature may result in damage of the electronic components or breakdown of the whole electronic device. For maintaining normal operations of the electronic device and extending the use life of the electronic device, it is important to dissipate the heat from the electronic device. 
     Generally, the heat-dissipating mechanism for removing heat from the optical components or electronic components of a high power electronic device (e.g. a projector or a personal computer) includes a heatsink with a plurality of heat pipes or a liquid cooling mechanism. However, the applications of the heatsink and the liquid cooling mechanism are restricted. As known, the heat of the components that generate high power and withstand low temperature can&#39;t be effectively removed by the heatsink or the liquid cooling mechanism. For increasing heat-dissipating efficiency and reliability, a thermoelectric cooling device is gradually used. 
     The thermoelectric cooling device is substantially a PN semiconductor device. When a current passes through the thermoelectric cooling device, two sides of the thermoelectric cooling device become a cold side and a hot side, respectively. Due to a temperature difference between the cold side and hot side, the temperature of the cold side is very low. The cold side of the thermoelectric cooling device is in contact with the component to be cooled. The hot side of the thermoelectric cooling device is hotter than the cold side. However, the use of the thermoelectric cooling device still has some drawbacks. For example, if the temperature of the cold side of the thermoelectric cooling device is lower than the ambient temperature, the thermoelectric cooling device and the inner component of the electronic device may result in dew or even generate moisture vapor. Under this circumstance, the reliability and the use life of the electronic device are reduced. 
     Therefore, there is a need of providing a controlling method for a thermoelectric cooling device and a heat-dissipating module using the thermoelectric cooling device in order to eliminate the above drawbacks. 
     SUMMARY OF THE INVENTION  
     The present invention provides a controlling method for a thermoelectric cooling device and a heat-dissipating module using the thermoelectric cooling device. By judging the relationship between the temperature of the cold side of the thermoelectric cooling device and the ambient temperature, the duty cycle corresponding to the electric energy to be received by the thermoelectric cooling device is selectively increased or decreased. In case that the temperature of the cold side of the thermoelectric cooling device is higher than or equal to the ambient temperature, the chilling efficiency of the cold side of the thermoelectric cooling device is enhanced by increasing the duty cycle. In case that the temperature of the cold side of the thermoelectric cooling device is lower than the ambient temperature, the duty cycle is decreased, so that the possibility of resulting in dew and generating moisture vapor is minimized. When the heat-dissipating module of the present invention is used to remove heat from electronic components of an electronic device, the influence of the moisture vapor on the electronic components are largely reduced. Consequently, the reliability and the use life of the electronic device are enhanced. 
     In accordance with an aspect of the present invention, there is provided a controlling method for a thermoelectric cooling device. The thermoelectric cooling device has a cold side and a hot side. In a step (a), the thermoelectric cooling device is enabled, and a temperature of the cold side and an ambient temperature around the thermoelectric cooling device are acquired. Then, a step (b) is performed to judge whether the ambient temperature is higher than or equal to a preset reference temperature. In a step (c), an initial value of a duty cycle corresponding to an electric energy to be received by the thermoelectric cooling device is set according to a judging result of the step (b). Then, a step (d) is performed to judge whether the temperature of the cold side is higher than or equal to the ambient temperature. In a step (e), if the judging condition of the step (d) is satisfied, the duty cycle is increased by a specified percentage, and the step (d) is repeatedly performed. In a step (f), if the judging condition of the step (d) is not satisfied, the duty cycle is decreased by the specified percentage and the step (d) is repeatedly performed by judging whether the duty cycle is higher than 0%. 
     In accordance with another aspect of the present invention, there is provided a heat-dissipating module. The heat-dissipating module comprises a thermoelectric cooling device, a power supply circuit, a first temperature sensor, a second temperature sensor, and a controller. The thermoelectric cooling device has a cold side and a hot side. The power supply circuit is electrically connected with the thermoelectric cooling device and operated at a duty cycle for providing electric energy to the thermoelectric cooling device and driving the thermoelectric cooling device. The first temperature sensor is disposed adjacent to the cold side of the thermoelectric cooling device for detecting the temperature of the cold side. The second temperature sensor is used for detecting the ambient temperature around the thermoelectric cooling device. The controller is electrically connected with the first temperature sensor, the second temperature sensor and the power supply circuit, judges whether the temperature of the cold side of the thermoelectric cooling device is higher than or equal to the ambient temperature according to a detecting result of the first temperature sensor and the second temperature sensor, and adjusts the duty cycle of the power supply circuit according to a judging result for adjusting the electric energy provided by the power supply circuit correspondingly. 
     The above contents of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is a schematic circuit block diagram illustrating the architecture of a heat-dissipating module according to an embodiment of the present invention; 
         FIG. 2  is a schematic view illustrates some components of the heat-dissipating module according to the embodiment of the present invention; 
         FIG. 3  is a flowchart illustrating a method for controlling a thermoelectric cooling device according to an embodiment of the present invention; and 
         FIG. 4  is a flowchart illustrating a method for controlling a thermoelectric cooling device according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. 
       FIG. 1  is a schematic circuit block diagram illustrating the architecture of a heat-dissipating module according to an embodiment of the present invention. As shown in  FIG. 1 , the heat-dissipating module  1  comprises a first temperature sensor  10 , a second temperature sensor  11 , a power supply circuit  12 , a controller  13 , and a thermoelectric cooling device  14 . The power supply circuit  12  is electrically connected with the thermoelectric cooling device  14 . Moreover, the power supply circuit  12  is operated at a specified duty cycle in order to provide electric energy to the thermoelectric cooling device  14  and drive the thermoelectric cooling device  14 . The thermoelectric cooling device  14  is a PN semiconductor device with a cold side  140  and a hot side  141  (see  FIG. 2 ). The cold side  140  and the hot side  141  are located at two opposite sides of the thermoelectric cooling device  14 . After the thermoelectric cooling device  14  is enabled by receiving the electric energy from the power supply circuit  12 , the cold side  140  of the thermoelectric cooling device  14  generates a chilling effect. Meanwhile, the hot side  141  is relatively hotter than the cold side  140 . The first temperature sensor  10  is used for detecting the temperature of the cold side  140  of the thermoelectric cooling device  14 . The second temperature sensor  11  is used for detecting an ambient temperature around the thermoelectric cooling device  14 , i.e. the ambient temperature around the heat-dissipating module  1 . 
     The controller  13  is electrically connected with the first temperature sensor  10 , the second temperature sensor  11  and the power supply circuit  12 . According to the detecting results of the first temperature sensor  10  and the second temperature sensor  11 , the controller  13  judges whether the temperature of the cold side  140  of the thermoelectric cooling device  14  is higher than or equal to the ambient temperature. According to the judging result, a duty cycle of the power supply circuit  12  is adjusted by the controller  13 . After the duty cycle of the power supply circuit  12  is adjusted, the electric energy provided by the power supply circuit  12  is correspondingly adjusted. 
       FIG. 2  is a schematic view illustrates some components of the heat-dissipating module according to the embodiment of the present invention. As shown in  FIGS. 1 and 2 , the cold side  140  of the thermoelectric cooling device  14  is located near an electronic component  9 . After the thermoelectric cooling device  14  is enabled, the cold side  140  of the thermoelectric cooling device  14  can cool the electronic component  9 . In addition, the first temperature sensor  10  is disposed adjacent to the cold side  140  of the thermoelectric cooling device  14 . Of course, the first temperature sensor  10  may be in direct contact with the cold side  140  of the thermoelectric cooling device  14  in order to measure the temperature of the cold side  140  more accurately. 
     Optionally, the heat-dissipating module  1  further comprises a plurality of fins  15 . As shown in  FIG. 2 , the fins  15  are disposed on the hot side  141  of the thermoelectric cooling device  14  for transferring the heat of the hot side  141  through thermal conduction. Optionally, the heat-dissipating module  1  further comprises a third temperature sensor  16 . The third temperature sensor  16  is located near or disposed on the hot side  141  of the thermoelectric cooling device  14 . Moreover, the third temperature sensor  16  is electrically connected with the controller  13 . The temperature sensor  16  is used for detecting the temperature of the hot side  141  of the thermoelectric cooling device  14 . In case that the temperature of the hot side  141  of the thermoelectric cooling device  14  exceeds a protective temperature, the controller  13  may control the power supply circuit  12  to stop providing electric energy to the thermoelectric cooling device  14 . Consequently, the heat-dissipating module  1  can be protected. The protective temperature may be previously determined according to the practical requirements. For example, the maximum withstandable temperature may be set as the protective temperature. 
     Hereinafter, a method for controlling the thermoelectric cooling device  14  by the controller  13  will be illustrated with reference to  FIGS. 1 ,  2  and  3 .  FIG. 3  is a flowchart illustrating a method for controlling a thermoelectric cooling device according to an embodiment of the present invention. Firstly, in the step S 1 , the heat-dissipating module  1  is enabled (i.e. the thermoelectric cooling device  14  is enabled). Then, in the step S 2 , the temperature of the cold side  140  of the thermoelectric cooling device  14  and the ambient temperature around the thermoelectric cooling device  14  are acquired. The temperature of the cold side  140  of the thermoelectric cooling device  14  is detected by the first temperature sensor  10 . The ambient temperature around the thermoelectric cooling device  14  is detected by the second temperature sensor  11 . Then, in the step S 3 , the controller  13  judges whether the ambient temperature is higher than or equal to a preset reference temperature. For example, the preset reference temperature is 30° C., but is not limited thereto. 
     Then, in the step S 4 , an initial value of a duty cycle of the power supply circuit  12  corresponding to the electric energy to be received by the thermoelectric cooling device  14  is set according to the judging result of the step S 3 . The step S 4  comprises two sub-steps S 40  and S 41 . In particular, either the sub-step S 40  or the sub-step S 41  is performed according to the judging result of the step S 3 . If the ambient temperature is higher than or equal to the preset reference temperature (e.g. 30° C.), the initial value of the duty cycle of the power supply circuit  12  is set as 50% by the controller  13 . That is, the sub-step S 40  is performed. Under this circumstance, since the power supply circuit  12  can provide higher electric energy to the thermoelectric cooling device  14  at the initial stage, the cooling rate of the cold side  140  of the thermoelectric cooling device  14  is higher. Meanwhile, in response to the high ambient temperature, the heat of the electronic component  9  can be quickly removed at the higher cooling rate by the thermoelectric cooling device  14 . 
     On the other hand, if the ambient temperature is lower than the preset reference temperature, the judging condition of the step S 3  is not satisfied. Meanwhile, the initial value of the duty cycle of the power supply circuit  12  is set as 0% by the controller  13 . That is, the sub-step S 41  is performed. Under this circumstance, since the ambient temperature is low, the power supply circuit  12  needn&#39;t to provide high electric energy to the thermoelectric cooling device  14  immediately and the cooling rate of the cold side  140  of the thermoelectric cooling device  14  is lower at the initial stage. Therefore, the initial value of the duty cycle of the power supply circuit  12  is set as 0% by the controller  13 . 
     After the step S 4 , the step S 5  is performed. In the step S 5 , the controller  13  judges whether the temperature of the cold side  140  of the thermoelectric cooling device  14  is higher than or equal to the ambient temperature. If the judging condition of the step S 5  is satisfied, the cold side  140  of the thermoelectric cooling device  14  will not result in dew. Consequently, the duty cycle of the power supply circuit  12  is continuously increased to increase the output electric energy of the power supply circuit  12 . Under this circumstance, the step S 6  is performed. In the step S 6 , the duty cycle of the power supply circuit  12  is increased by a specified percentage (e.g. 1%) by the controller  13 . Meanwhile, the temperature of the cold side  140  is continuously decreased, and the chilling effect is enhanced. Consequently, the heat of the electronic component  9  can be quickly removed at the higher cooling rate by the thermoelectric cooling device  14 . 
     On the other hand, if the judging condition of the step S 5  is not satisfied, the cold side  140  of the thermoelectric cooling device  14  may result in dew and generate moisture vapor. For minimizing the possibility of resulting in dew and generating moisture vapor, the duty cycle of the power supply circuit  12  should be decreased. Then, the step S 7  is performed to judge whether the duty cycle of the power supply circuit  12  is higher than 0%. If the judging condition of the step S 7  is not satisfied (Namely, if the duty cycle of the power supply circuit  12  is equal to 0%), the step S 5  is performed again. Whereas, if the judging condition of the step S 7  is satisfied, the step S 8  is performed. In the step S 8 , the duty cycle of the power supply circuit  12  is decreased by a specified percentage (e.g. 1%) by the controller  13 . Since the duty cycle of the power supply circuit  12  is decreased, the output electric energy of the power supply circuit  12  is decreased. Under this circumstance, the temperature of the cold side  140  of the thermoelectric cooling device  14  is gradually increased, and the possibility of resulting in dew and generating moisture vapor is minimized. 
       FIG. 4  is a flowchart illustrating a method for controlling a thermoelectric cooling device according to another embodiment of the present invention. In this embodiment, the sub-step S 40  of the step S 4  of  FIG. 3  is replaced by the sub-step S 40 ′. In the step S 40 ′, an initial value of a duty cycle of the power supply circuit  12  corresponding to the electric energy to be received by the thermoelectric cooling device  14  is set according to the judging result of the step S 3  after a delaying time. Under this circumstance, the cooling rate of the cold side  140  of the thermoelectric cooling device  14  is gradually increased, and the heat of the electronic component  9  is gradually removed by the thermoelectric cooling device  14 . Consequently, the possibility of resulting in dew and generating moisture vapor is minimized. 
     From the above descriptions, the present invention provides a controlling method for a thermoelectric cooling device and a heat-dissipating module using the thermoelectric cooling device. By judging the relationship between the temperature of the cold side of the thermoelectric cooling device and the ambient temperature, the duty cycle corresponding to the electric energy to be received by the thermoelectric cooling device is selectively increased or decreased. In case that the temperature of the cold side of the thermoelectric cooling device is higher than or equal to the ambient temperature, the chilling efficiency of the cold side of the thermoelectric cooling device is enhanced by increasing the duty cycle. In case that the temperature of the cold side of the thermoelectric cooling device is lower than the ambient temperature, the duty cycle is decreased, so that the possibility of resulting in dew and generating moisture vapor is minimized. When the heat-dissipating module of the present invention is used to remove heat from electronic components of an electronic device, the influence of the moisture vapor on the electronic components are largely reduced. Consequently, the reliability and the use life of the electronic device are enhanced. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.