Patent Abstract:
A cooling device for projector, comprising a light source, an exhaust fan, an air directing fan, an air duct, air inlet windows, an optical engine, a circuit board, a light cut, and a power supply to constitute a projector device with high brightness and high contrast. The projector includes a design that directs hot air flow directly into fan blades of an exhaust fan, thereby effectively reducing adverse effects and solving problems of conventional technology, such as failure to direct hot air flow into the fan blades of the exhaust fan, resulting in excessively high average temperature in the fan hub area that is in alignment with the hot air current, and high working temperature of motor bearings, control circuits, rotors and stators in the fan hub, so that the fan hub can be operating under lower temperatures, thereby enhancing normal performance, effective working life and reliability of the fan and the projector.

Full Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The invention relates to a cooling device for a projector, and particularly to a cooling device that direct hot air directly into fan blades to reduce temperature of fan hub. 
     2. Description of the Prior Art 
     Please refer to FIG. 1 that illustrates a prior art of projector  10 , comprising a light source  121  of a light unit  12  inside a casing  11 , the light source  121  creating a high-brightness and high-contrast projecting light ray  122  when acted on by an optical engine  13   m . A light cut  123  installed on the upper side of the light unit  12  to obstruct the light source  121  of the light unit  12 . In the prior art, heated air is subject to the action of a first fan  157 , air entering the projector  10  through a first air inlet window  151  becomes a first hot current  153 , which after passing a first printed circuit board  141  is separated into a third hot current  155  and a fourth hot current  156 . The third hot current  155  passing a first fan  157  and fan blades  1572  is exhausted out of the projector  10 , and the fourth hot current  156  is directed through the third fan  162  into the light source heat exhausting unit  16 . On the other hand, when subjected to action by the second fan  158 , air enters through the second air inlet window  152  into the projector  10 , creating a second hot current  154 . The second hot current  154  respectively passes an optical engine  13 , a second printed circuit board  142  and a light unit  12 , then through a plurality of fan blades  1582  of the second fan  158 , finally out of the projector  10 . 
     Due to the action of the second fan  158 , the fourth hot current  156  directed through the third fan  162  into the light source heat exhausting unit  16  passes an air duct  161  to absorb the heat generated by the light source  121 , so the temperature of the fourth hot current  156  rises rapidly. After passing the light cut  123 , the fourth hot current  156  in the prior art of projector  10  is squarely aligned with the second fan  158 , then the second hot current  154  is exhausted out of the projector  10  by the action of the fan blades  1582  of the second fan  158 . 
     A shortcoming in the prior art of projector  10  lies in that the heat radiating direction of the fourth hot current  156  is squarely in alignment with the second fan  158  or the second fan hub  1581 . The heat generated by the light source  121  of the light unit  12  is the highest in the projector  10 , so the heat carried by the fourth hot current  156  after passing the light cut  123  is also the highest. Accordingly, when the fourth hot current  156  exhaust heat directly against the second fan hub  1581 , the heat will be collected at the front of the second fan hub  1581  before it passes a plurality of second fan blades  1582  and out of the projector  10 , forming a higher average temperature at the front of the second fan hub  1581 . As shown in FIG. 5, when the prior art of the projector  10  is operating under room temperature using a light source  12  of approximately 130 Watt, the air temperature at 1 mm position  159  to the front of the center of the second fan hub  1581  will reach as high as 206.6 degrees Fahrenheit, which is higher than the maximum operating temperature of 194 degrees Fahrenheit for the second fan  158 , resulting in adverse effects to the motor bearings, control circuits, rotors, stators and such key components in the hub of the second fan  158 , thereby reducing the working life and reliability of the second fan  158 . 
     As shown in FIG. 2 that illustrates another prior art of projector  20 , comprising a casing  21 , a light unit  22 , a light source  221 , an optical engine  23 , a light cut  223 , a first printed circuit board  241 , a second printed circuit board  242 , a cooling device  25 , a first air inlet window  251 , a second air inlet window  252 , a first fan  257 , a light source heat exhausting unit  26 , a third fan  262 , an air outlet  263  and an air inlet  261 , which are the same as the first prior art, but different in that the second fan  258 , the fan hub  2581  and the fan blades  2582  are installed at a rear part of the light source  221 . It has the shortcoming that the heat carried by the fourth hot current  256  is also the highest. As a result, when heat is exhausted in a lower right direction from a specified distance between the fourth hot current  256  and the second fan  258 , the heat will be collected at the front of the second fan hub  2581  before passing the second fan blades  2582  and out of the projector  20 , forming a higher average temperature at the front of the second fan hub  2581 , bringing adverse effects to the motor bearings, control circuits, rotors, stators and such key components in the second fan hub  2581 , reducing the working life and reliability of the second fan  258  and the prior art of the projector  20 . 
     SUMMARY OF INVENTION 
     The objective of the invention is to provide a cooling device for projector, to direct hot current directly into fan blades, thereby reducing the temperature of the fan hub, and increasing the working life and reliability of the product. 
     To achieve the above objective, the present invention involves a light source that provides light to the projector device. With an air duct extending from the light source to a second exhaust fan, so air in the vicinity of the light source is exhausted through the second fan blades and out of the projector, wherein the second exhaust fan comprises a second fan hub and a plurality of second fan blades, the second fan hub being located at a center of the second exhaust fan, the second fan blades respectively connected to a periphery of the second fan hub, thereby the air in the vicinity of the second fan blades in the projector is exhausted through the second fan blades and out of the projector. The air duct is in a closed status at the periphery of the light source, concentrating a direction for exhaustion, and the air outlet is squarely aligned with the second fan blades. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     For better understanding of the characteristics and technical contents of the present invention, please refer to the following description and drawings. 
     FIGS. 1 and 2 are respectively section views of two types of prior art of projector. 
     FIGS. 3 and 4 are respectively section views of a first preferred embodiment and a second preferred embodiment of the present invention of a cooling device for projector. 
     FIG. 5 is a schematic view of a position at 1 mm to a front of a center of second fan hub in the prior art. 
     FIG. 6 is view of relationship between a second fan, a light cut and an air outlet in the first preferred embodiment of the invention of a cooling device for projector. 
     FIG. 7 is a view of relationship between a second fan, a light cut and an air outlet in the second preferred embodiment of the invention of a cooling device for projector. 
     FIG. 8 is a view of related temperatures of a second fan including a second fan hub and a plurality of second fan blades, a light cut and an air outlet in the prior art of projector. 
     FIG. 9 is a view of related temperatures of a second fan including a second fan hub and a plurality of second fan blades, a light cut and an air outlet in the present invention of a cooling device for projector. 
     FIG. 10 is a view of a third preferred embodiment of the present invention including two air outlets. 
     FIG. 11 is a view of a fourth preferred embodiment of the present invention including three air outlets. 
     FIG. 12 is a view of a fifth preferred embodiment of the present invention including a ring-shaped air outlet. 
    
    
     DETAILED DESCRIPTION 
     The following description with drawings of the present invention is used for presentation purpose only, not to limit the present invention. 
     As shown in FIG. 3 that shows a first preferred embodiment of the present invention of projector  30 , comprising a light source  321  of a lighting unit  32  inside a casing  31 , producing byway of action of an optical engine  33  a high-brightness and high-contrast projector light ray  322 . On a side of the lighting unit  32  is installed a light cut  323  that serves to obstruct the light source  321  of the lighting unit  32 . The projector  30  further comprises a first printed circuit board  341 , a second printed circuit board  342  and a power supply (not shown in drawing), providing power and control to the projector  30 . The light source  321 , the first printed circuit board  341 , the second printed circuit board  342 , the optical engine  33  and the power supply generate heat during their operation. 
     The projector  30  provides exhausting heat by means of a cooling device  35 . The cooling device  35  comprises a plurality of first air inlet windows  351  and a plurality of second air inlet windows  352 , where cooling air entering through the first air inlet windows  351  or the second air inlet windows  352  into the projector  30  from outside the projector  30 . A first fan  357  for ventilation purpose is installed at an opening on the housing  31  at a lower right corner of the projector  30 , having a first fan hub  3571  and a plurality of first fan blades  3572 , to exhaust hot air out of the projector  30 . Between the housing  31  and the light cut  323 , a second fan  358  for ventilation purpose is installed at an opening on a housing  31  at an upper part of the projector  30 , having a second fan hub  3581  and a plurality of second fan blades  3582  to expire hot air out of the projector  30 , and a light source heat exhausting unit  35 , consisting of an air duct  361  surrounding the light source  321 , comprises a third fan  362  and an air outlet  363 , the third fan  362  being an air guide fan installed at an inlet of the air duct  361 , with a direction of air entrance at one side of the first fan  357 , a part of the heated air in the vicinity of the first fan  357  and the third fan  362  is expired through the first fan  357  out of the projector  30 , while another part thereof is guided into the light source heat exhausting unit  36  through the third fan  362 . 
     The heated air in the first preferred embodiment of the invention flows in a direction as described in the following sequence. The air entering through the second air inlet windows  352  into the projector  30  is sucked by the second fan  358 , producing a second hot current  354 , the second hot current  354  passes respectively the operating optical engine  33 , the second printed circuit board  342  and the lighting unit  32 , with temperature rising gradually, then through the second fan blades  3582  of the second fan  358  and out of the projector  30 . On the other hand, the air entering through the first air inlet windows  351  into the projector  30  is sucked by the first fan  357 , producing a first hot current  353 , the first current  353  passes the periphery of the first printed circuit board  341  before it is divided into two parts, a third hot current  355  and a fourth hot current  356 . The third hot current  355  passing through the first fan  357  and out of the projector  30 , and the fourth hot current  356  passes through the third fan  362  and into the light source heat exhausting unit  36 . On the other hand, due to the suction by the second fan  358 , the fourth hot current  356  entering the light source heat exhausting unit  36  through the third fan  362  enters an inlet of the air duct  361  to reach the light source  321 , absorbing the heat generated by the lighting source  321 , when temperature rises rapidly. After passing through the light cut  323 , the fourth hot current  356  is aligned with the second fan  358 , and is then sucked by the second fan  358  out of the projector  30 . The air outlet  363  of the fourth hot current  356  of the invention of projector is aligned with the second fan blade  3582 . 
     Please refer to FIG. 6, the air outlet  363  disclosed in the present invention of projector  30  is aligned with the second fan blades  3582 , at a minimum distance from the second fan blades  3582 , so the fourth hot current  356  escaping the air outlet  363  can be directly directed into the second fan blades  3582 , and rapidly expulsed from the projector  30 . Therefore, at the moment when the fourth hot current  356  escapes the air outlet  363 , the fourth current  356  is directed directly to the second fan blades  3582  across a minimum distance, and immediately out of the second fan  358 , which effectively solves the problem in the conventional model of projector  10  wherein heat is collected at the front of the second fan hub  1581 , thereby reducing the air temperature at 1 mm to the front of the center of the second fan hub  1581  from 206.6 degrees to 174 degrees Fahrenheit, as shown in FIG.  5 . 
     FIG. 4 illustrates a second preferred embodiment of the invention of projector  40 , having a casing  41 , a lighting unit  42 , a light source  421 , an optical engine  43 , a light cut  423 , a first printed circuit board  441 , a second printed circuit board  442 , a power supply (not shown in drawing), a cooling device  45 , a first air inlet window  451 , a second air inlet window  452 , a first fan  457 , a light source heat exhausting unit  46 , an air duct  461 , a third fan  462  and an air outlet  463 , which are approximately the same as those of the first preferred embodiment of projector  40 , with an only difference that the second fan  458  is installed at the rear of the light source  421 . Wherein, due to suction of the second fan  458 , the fourth hot current  456  directed through the third fan  462  into the light source heat exhausting unit  46  passes the air duct  461 , absorbing the heat generated by the light source  421  in heat convection, therefore the rapidly rising temperature. The air duct  461  extends to the right to the rear air duct  462  and passes the light cut  423 , as shown in FIG. 7, the air duct  461  in the present invention extends to the right side, the air duct outlet  463  is aligned with the second fan blades  4582 , at a minimum distance from the second fan blades  4582 , thereby to induct directly the fourth hot current  456  escaping from the air outlet  463  into the second fan blades  4582  and rapidly out of the projector  40 . As described above, the present invention has effectively solved the problem of higher average temperature at the front of the second fan hub  2581  where heat is accumulated before passing the second fan blades  2582 . 
     Please refer to FIG. 8 for comparison of temperature distribution between the present invention and the prior art. Take the prior art of projector  10  as an example to see the temperature distribution of the second fan hub  1581 . Since the direction of heat radiation of the fourth hot current  156  of the prior art of projector  10  is aligned with the second fan hub  1581 , a higher average temperature T occurs in the zone crossed by oblique lines at the front of the second fan hub  1581 . As shown in FIG. 9, the present invention of projector  30  is taken as an example, since the air outlet  363  is aligned with the second fan blades  3582 , at a minimum distance from the second fan blades  3582 , therefore the fourth hot current  356  escaping the air outlet  363  can be directed directly into the second fan blades  3582 , and rapidly out of the projector  30 . As a result, temperature is the highest because heat is collected in the region crossed with oblique lines of the second fan blades  3582  squarely aligned with the air outlet  363 , having an average temperature of T 2 . Meanwhile, since the second fan hub  3581  (region crossed with oblique lines) is not aligned with the air outlet  363 , the heat is not concentrated, and so the temperature is lower, average temperature at T 1 . 
     It is known from the above that, the average temperature T affecting the second fan hub  1581  and the second fan blades  1582 , in FIG. 8, is lower than the average temperature T 2  affecting the second fan blades  3582 , but higher than the average temperature T 1  affecting the second fan hub  3581 , or T 1 &lt;T&lt;T 2 . In other words, the present invention discloses the characteristic of the air outlet in direct alignment with the second fan blades and a minimum distance (approximately 1 mm˜5 mm) between the air outlet and the second fan blades, to enable direct induction of the fourth hot current escaping the air outlet into the second fan blades and quickly out of the projector  40 . What is disclosed by the present invention is that, high heat and high temperature T 2  is collected in the heat-resistant zone of the second fan blades, causing the average temperature T 1  of the second fan hub to drop to the average temperature T affecting the second fan hub in the prior art, thereby reducing the operating temperature of motor bearings, control circuits, rotors, stators and such key components in the fan hub, so there will be no adverse effects caused by high temperature, so as to increase the effective life and reliability of the fans and the device. 
     Please refer to FIG. 10 that illustrates a third preferred embodiment of the prevent invention of projector comprising two air outlets  511 ,  512 , each aligned with the second fan blades  3582 . 
     Please refer to FIG. 11 that illustrates a fourth preferred embodiment of the present invention of projector comprising three air outlets  521 ,  522 ,  523 , each aligned with the second fan blades  3582 . 
     Please refer to FIG. 12 that illustrates a fifth preferred embodiment of the present invention of projector comprising a ring-shaped air outlet  531 , the ring-shaped air outlet  531  aligned with the second fan blades  3582 . 
     It is to be understood that the above description covering some of the preferred embodiments of the present invention shall not be based to restrict or limit the range of applicability of the present invention, and that all modifications or variations made without departing from the spirit of the invention shall be included in the subject claim. Furthermore, the invention has not been seen in any public occasions or publications, therefore, having satisfied the requirements of “applicability, novelty and inventive step” this application is filed for a patent right. Your favorable consideration will be appreciated.

Technology Classification (CPC): 5