Abstract:
A cooling system for cooling a heat source and a projection apparatus having the same are disclosed. The cooling system includes a heat dissipating device and a thermoelectric cooler (TEC). The heat source is disposed on the side of the heat dissipating device. The TEC is disposed on the other side of the heat dissipating device corresponding to the heat source. The TEC is initiated as the temperature of the heat source is greater than the first value, while the TEC is shut off as the temperature of the heat source is lower than the second value. Therefore, the cooling system economizes the energy by controlling the operation of the TEC according to the temperature of the heat source.

Description:
This application claims priority to Taiwan Patent Application No. 099140743 filed on Nov. 25, 2010, the disclosure of which is incorporated herein by reference in its entirety. 
     CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention provides a cooling system, and more particularly, to a cooling system with a power saving function and a projection apparatus having the cooling system. 
     2. Descriptions of the Related Art 
       FIG. 1  is a schematic diagram of a cooling system  10  in a conventional projector. The cooling system  10  uses a thermoelectric cooler (TEC) to dissipate heat generated during the operation of the projector. As shown in  FIG. 1 , the conventional cooling system  10  comprises a thermoelectric cooler  14  and a heat dissipating module  16 . The thermoelectric cooler  14  is disposed at the first side of a heat source  12 , while the heat dissipating module  16  is disposed at the second side of the thermoelectric cooler  14  opposite to the heat source  12 . The heat source  12  may be a light source consisting of light emitting diodes (LEDs) in the projector or other elements tending to generate intense heat in the projector. The heat dissipating module  16  may be a heat sink fin set, a heat sink fin set installed with heat pipes, a liquid cooling device or a condensing cooling device. 
     During the operation of the aforesaid conventional projector, the heat source  12  may generate extremely intense heat. In such a case, the user has to initiate the thermoelectric cooler  14  to assist the heat dissipating module  16  in cooling the heat source  12 , such that the heat dissipating efficiency of the heat dissipating module  16  may be improved. Recently, in regards to the common thermoelectric cooler  14 , the heat conduction principle thereof is to dissipate heat by means of a temperature difference between the cold and hot end of a semiconductor after being powered on. The operation of the thermoelectric cooler  14  requires the consumption of a great amount of power. Moreover, when the thermoelectric cooler  14  is turned off, the thermoelectric cooler  14  presents great thermal resistance instead of becoming a poor heat conductor. As a result, for the purposes of heat dissipation, conventional projectors with a thermoelectric cooler must, during the operation, continuously consume a large amount of electric power to keep the thermoelectric cooler operating while assisting the heat dissipating module  16  in dissipating heat. Accordingly, the consumption of a large amount of electric power is not desired in the current market of saving power and protecting the environment. 
     SUMMARY OF THE INVENTION 
     The objective of the present invention is to provide a cooling system with both an excellent heat dissipating capability and an excellent power saving function and a projection apparatus having the cooling system to solve the aforesaid problem in the prior art. 
     To achieve the aforesaid objective, the claims of the present invention disclose a cooling system with a power saving function for cooling a heat source. The cooling system comprises a heat dissipating device and at least one thermoelectric cooler (TEC). The heat source is disposed at the first side of the heat dissipating device, while the thermoelectric cooler is disposed at the second side of the heat dissipating device opposite to the heat source without coming into direct contact with the heat source. The thermoelectric cooler is initiated to assist the heat dissipating device in dissipating heat generated from the heat source when the temperature of the heat source is greater than the first value, and is shut off when the temperature of the heat source is lower than the second value. 
     To achieve the aforesaid objective, the claims of the present invention further disclose a projection apparatus. The projection apparatus comprises a heat source, a cooling system and a controller. The cooling system comprises a heat dissipating device and at least one thermoelectric cooler. The heat source is disposed at the first side of the heat dissipating device, while the thermoelectric cooler is disposed at the second side of the heat dissipating device opposite to the heat source without coming into direct contact with the heat source.  The thermoelectric cooler is initiated to assist the heat dissipating device in dissipating heat generated from the heat source when the temperature of the heat source is greater than the first value, and is shut off when the temperature of the heat source is lower than the second value. The controller is coupled to the thermoelectric cooler for initiating or shutting off the thermoelectric cooler according to the temperature of the heat source. 
     With the arrangement of a cooling system and projection apparatus having the same described above, the present invention can initiate the thermoelectric cooler to assist the heat dissipating device in dissipating heat when the temperature of the heat source is higher and shut off the thermoelectric cooler to save electric power when the temperature of the heat source is lower. Therefore, the projection apparatus of the present invention can satisfy both the requirements of saving energy and protecting the environment, while efficiently dissipating high heat. 
     The detailed technology and preferred embodiments implemented for the subject invention are described in the following paragraphs accompanying the appended drawings for people skilled in this field to well appreciate the features of the claimed invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a cooling system of the prior art; 
         FIG. 2  is a schematic functional block diagram of a projection apparatus according to the preferred embodiment of the present invention; 
         FIG. 3  is a schematic diagram of a projection apparatus according to the preferred embodiment of the present invention; 
         FIG. 4  is a side view diagram of a cooling system according to the first embodiment of the present invention; 
         FIG. 5  is a top view diagram of the cooling system according to the first embodiment of the present invention; 
         FIG. 6  is a side view diagram of a cooling system according to the second embodiment of the present invention; 
         FIG. 7  is a schematic diagram of a cooling system according to the third embodiment of the present invention; and 
         FIG. 8  is a schematic view diagram of a cooling system according to the fourth embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Because the present invention focuses on the design of the cooling system, the following description will put emphasis only on the features and embodiments which are described in detail in conjunction with the attached drawings by taking only the cooling system and main peripheral elements of a projection apparatus as examples. The other elements not directly related to the cooling system are omitted from depiction. It shall be appreciated that the embodiments of the present invention are not intended to limit the present invention to any specific environment, the applications or particular implementations described in these embodiments. Furthermore, the attached drawings are all schematic views depicted in a simplified way or on a slightly exaggerated scale. The elements shown therein are not to define the number, shape or dimensional scale of these elements in practical implementations but are only of an optional design. Therefore, the actual arrangement of the elements may be more complex, and this shall be stated beforehand hereby. 
     First,  FIG. 2  illustrates a schematic functional block diagram of a projection apparatus  20  according to the preferred embodiment of the present invention. The projection apparatus  20  comprises a cooling system  22 , a heat source  26  and a controller  30 . The cooling system  22  comprises a heat dissipating device  24  disposed at the first side of the heat source  26 . In application, the heat dissipating device  24 , which may be a set of heat sink fins, a heat sink fin module installed with a heat pipe, a liquid cooling device or a condensing cooling device, is adapted to dissipate heat generated by the heat source  26 . Also, the cooling system  22  further comprises at least one thermoelectric cooler (TEC)  28 , which is disposed at the second side of the heat dissipating device  24  opposite to the heat source  26  or is contained in a recessed structure formed at the second side. That is, the thermoelectric cooler  28  and the heat source  26  are installed on the two opposite sides of the heat dissipating device  24  respectively and do not come into contact with each other in space. 
     To effectively reduce the electric energy consumed by the projection apparatus  20 , the projection apparatus  20  comprises a controller  30  that is electrically coupled to the thermoelectric cooler  28 . When the detected temperature of the heat source  26  is greater than the first value (e.g. Celsius 80 degree), the controller  30  initiates the heat dissipating device  24  and the thermoelectric cooler  28  simultaneously, such that the thermoelectric cooler  28  can assist the heat dissipating device  24  in accelerating the dissipation of heat generated from the heat source  26 . On the other hand, when the detected temperature of the heat source  26  is lower than the second value (e.g. Celsius 75 degree), the controller  30  shuts off the thermoelectric cooler  28  and only keeps the heat dissipating device  24  operating to effectively reduce the electric energy consumed by the projection apparatus  20 . The first value is substantially greater than the second value. In other words, when the temperature of the heat source  26  is higher than Celsius 80 degrees, the controller  30  initiates the thermoelectric cooler  28  to assist the heat dissipating device  24  in accelerating the dissipation of heat. When the temperature of the heat source  26  is lower than Celsius 75 degrees, the controller  30  shuts off the thermoelectric cooler  28  to save electric energy. The controller  30  modulates the initiation/shutting off of the thermoelectric cooler  28  within a buffering range, i.e., the temperature range between Celsius 75 degrees and Celsius 80 degrees. As such, when the temperature of the heat source  26  falls at a specific initiation/shutting off point, the buffering range can prevent the controller  30  from repeatedly initiating/shutting off the thermoelectric cooler  28 . Accordingly, the inventive feature of the present invention is that the thermoelectric cooler  28  is selectively initiated to save energy. 
     Next,  FIG. 3  illustrates a schematic diagram of a projection apparatus  20  according to the preferred embodiment of the present invention. In this embodiment, the primary heat source of the projection apparatus  20  is a light source module  27 . Generally, the projection apparatus  20  may further comprise an optical system  32 , a control system  34  and a power system  36 . The control system  34  and the power system  36  are respectively adapted to control the functional operation and the electric power modulation of the projection apparatus  20 . It shall be particularly emphasized that the light source module  27  may be used as a backlight source of the optical system  32 . Furthermore, the control system  34  and the power system  36  may also be considered as heat sources of the projection apparatus  20  in practice. Accordingly, the cooling system  22  may further be installed on any system that generates heat in the projection apparatus  20  as required. Consequently, the number and the installation position(s) of the cooling system(s)  22  or the number and the installation position(s) of the thermoelectric cooler(s)  28  are not limited to what has been described in the aforesaid embodiment but shall be determined depending on the design requirements. 
     Next, in reference to  FIGS. 4 ,  5  and  6 ,  FIG. 4  is a side view diagram of the cooling system  22  according to the first embodiment of the present invention,  FIG. 5  is a top view diagram of the cooling system  22  according to the first embodiment of the present invention, and  FIG. 6  is a side view diagram of a cooling system according to the second embodiment of the present invention. As shown in  FIG. 4 , in the first embodiment, the heat dissipating device  24  may be a set of heat sink fins or a heat sink fin module installed with a heat pipe. The heat source  26  and the thermoelectric cooler  28  are installed on two sides of the heat dissipating device  24  respectively without coming into contact with each other. Therefore, even if the cooling system  22  only initiates the heat dissipating device  24  for dissipating heat, the thermoelectric cooler  28  in the OFF state will not become a thermal resistor between the heat source  26  and the heat dissipating device  24 ; i.e., the cooling system  22  can selectively initiate only the heat dissipating device  24  or both the heat dissipating device  24  and the thermoelectric cooler  28  without adversely affecting the heat dissipating efficiency thereof. Furthermore, as shown in  FIG. 5 , the lateral surface of the thermoelectric cooler  28  that comes into contact with the second side of the heat dissipating device  24  is substantially no greater than the second side of the heat dissipating device  24 . The thermoelectric cooler  28  is located at a position adjacent to the center  24   a  of the second side of the heat dissipating device  24 . The center  28   a  of the thermoelectric cooler  28  and the center  24   a  of the heat dissipating device  24  are disposed correspondingly to each other, such that the thermoelectric cooler  28  can effectively increase the temperature difference between the heat dissipating device  24  and the heat source  26  and reinforce the flux of heat conduction flow. In such a case, the dissipation of heat generated from the heat source  26  may be accelerated, and thereby the thermoelectric cooler  28  can achieve the efficacy of optimized heat dissipation. In the first embodiment, the lateral surface area of the thermoelectric cooler  28  is smaller than that of the heat dissipating device  24 . Specifically, the lateral surface area of the thermoelectric cooler  28  is substantially equal to eight percent of the lateral surface area of the heat dissipating device  24 . The aforesaid area distribution ratio obtained through experimentation with which the cooling system  22  can present the optimal heat dissipating efficiency. Furthermore, as shown in  FIG. 6 , the second embodiment of the present invention is a modified form of the first embodiment. The differences between the second embodiment and the first embodiment is only in that, as can be seen from the cross-sectional side diagram of the second embodiment, the heat dissipating device  24  has a recessed structure  50 . The thermoelectric cooler  28  can be buried and embedded in the recess of the recessed structure  50 . 
     Finally, with reference to both  FIGS. 7 and 8 ,  FIG. 7  is a schematic diagram of the cooling system  22  according to the third embodiment of the present invention.  FIG. 8  is a schematic diagram of the cooling system  22  according to the fourth embodiment of the present invention. In the third embodiment, a liquid cooling device is used as the heat dissipating device  24  of the cooling system  22 ; in the fourth embodiment, a condensing cooling device is used as the heat dissipating device  24  of the cooling system  22 . The characteristics within both the third embodiment and the fourth embodiment identical to the aforesaid embodiments are in that the thermoelectric cooler  28  is also installed at the side of the heat dissipating device  24  opposite the heat source  26 . The thermoelectric cooler  28  and the heat source  26  do not have direct contact with each other. Accordingly even if the thermoelectric cooler  28  is not initiated, the heat generated from the heat source  26  can still be dissipated outwards rapidly through the heat dissipating device  24  without being affected by the thermal resistance of the thermoelectric cooler  28 . 
     Compared with the prior art, the projection apparatus of the present invention has a thermoelectric cooler installed beside the heat dissipating device without coming into contact with the heat source; for example, the heat dissipating device is usually disposed between the heat source and the thermoelectric cooler. The ratio of the lateral surface area of the thermoelectric cooler to that of the heat dissipating device and the installation positions of the thermoelectric cooler and the heat dissipating device are determined on the basis of the strict experimental data, such that the thermal resistance of the thermoelectric cooler before being initiated will not affect the heat dissipation mechanism through which the heat dissipating device dissipates heat generated from the heat source. Furthermore, the controller of the projection apparatus of the present invention can set a condition for triggering the thermoelectric cooler (e.g., a temperature varying range) according to actual environment requirements, such that the thermoelectric cooler can be initiated to assist the heat dissipating device in dissipating heat when the temperature of the heat source is higher and be shut off to save electric energy when the temperature of heat source is lower. Therefore, the projection apparatus of the present invention can satisfy both the requirements of saving energy and protecting the environment, as well as efficiently dissipate high heat.