Abstract:
An illumination device includes a light source and a heat-dissipation device. The heat-dissipation device has an air impeller configured for dissipating heat from the light source, and a hollow shell. The hollow shell has an inlet and an outlet with a height difference therebetween. The air impeller is removably installed on the shell between the inlet and outlet. The air impeller is adjacent to the outlet and accelerates airflow therefrom. Air pressure around the outlet is reduced and a pressure difference between the inside and outside of the hollow shell is generated. Air in hollow shell is heated by the light source and leaves the hollow shell via the outlet. Cold air enters the hollow shell via the inlet.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The disclosure relates generally to illumination, and more particularly to an illumination device with high heat-dissipation efficiency. 
         [0003]    2. Description of the Related Art 
         [0004]    In general, an LED-based illumination device employs a heat-dissipation module, such as a fan, to dissipate heat generated by the LED. However, the fan is often fixed on the heat-dissipation module, making removal, cleaning, and maintenance difficult. If the fan fails, the LED can easily overheat, with shortened lifetime rapidly occurring. Thus, what is called for is an illumination device utilizing a heat dissipation system that can alleviate the limitations described. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a perspective view of an illumination device in accordance with a first embodiment of the disclosure. 
           [0006]      FIG. 2  is an exploded view of the illumination device in  FIG. 1 . 
           [0007]      FIG. 3  is a cross-section of an illumination device in accordance with a second embodiment of the disclosure. 
           [0008]      FIG. 4  is a cross-section of an illumination device in accordance with a third embodiment of the disclosure. 
           [0009]      FIG. 5  is a cross-section of an illumination device in accordance with a fourth embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    Referring to  FIG. 1  and  FIG. 2 , an illumination device  100  in accordance with a first embodiment of the disclosure includes a light source  11  and a heat-dissipation device  12 . 
         [0011]    The light source  11  includes a plurality of light emitting diodes (LEDs)  111  and a substrate  112 . The substrate  112  includes a first surface  1121  and a second surface  1122 . The second surface  1122  is opposite to the first surface  1121 . The LEDs  111  are mounted on the first surface  1121 , and electrically connected to the substrate  112 . The first surface  1121  faces away from the heat-dissipation device  12 . 
         [0012]    The heat-dissipation device  12 , mounted on the second surface  1122  and thermally connected to the substrate  112 , includes a plurality of cooling fins  121 , a hollow shell  123 , and an air impeller  125 , such as fan. 
         [0013]    The cooling fins  121  are received in the hollow shell  123 . 
         [0014]    The hollow shell  123  includes a first side surface  123   a , a second side surface  123   b , and an upper surface  123   c . The second side surface  123   b  is opposite to the first side surface  123   a . The upper surface  123   c  is adjacent to the first side surface  123   a  and the second side surface  123   b . At least one inlet  122  is defined in the first side surface  123   a  and at least one outlet  124  in the upper surface  123   c . Optimally, the at least one outlet  124  is located on the upper surface  123   c , configured away from the first side surface  123   a , and adjacent to the second side surface  123   b.    
         [0015]    When the hollow shell  123  is in normal use, the upper surface  123   c  is higher than the first side surface  123   a  and the second surface  123   b.    
         [0016]    The air impeller  125  is located on the upper surface  123   c , and out of the hollow shell  123 . Optimally, the air impeller  125  is located between the inlet  122  and the outlet  124 , and adjacent to the outlet  124 . In the first embodiment, the air impeller  125  is a fan mounted on the upper surface  123   c  by screws or mounting rabbets. 
         [0017]    When the heat generated by the LEDs  111  is dissipated into the air via the cooling fins  121 , the air temperature in the hollow shell  123  increases. The hot air rises to leave the hollow shell  123  through the outlet  124 , generating a convection loop. Further, the air impeller  125  accelerates the airflow around the outlet  124 . According to the Bernoulli principle, when the velocity of the air is increased, air pressure decreases; and when the velocity of the air is decreased, the air pressure is increased. Because there is a pressure difference, the air flows from high pressure to low pressure areas, and accordingly, the convection loop between the inside and outside of the hollow shell  123  is accelerated so as to exhaust the hot air from the hollow shell  123 . 
         [0018]    The airflow direction C generated by the air impeller  125  is perpendicular to the airflow direction B generated by the heated air through the outlet  124 . The air impeller  125  exhausts the hot air along the airflow direction C. Cold air enters the hollow shell  123  via the inlet  122 . This shows that the air convection loop generated by the air impeller  125  accelerates the air circulation in the hollow shell  123  so as to dissipate the heat generated by the light source  11  more efficiently. 
         [0019]    Referring to  FIG. 3 , the illumination device  200  in accordance with a second embodiment of the disclosure includes a light source  21  and a heat-dissipation device  22 . 
         [0020]    The light source  21  includes a plurality of LEDs  211  and a substrate  212 . The substrate  212  includes a first surface  2121  and a second surface  2122 . The second surface  2122  is opposite to the first surface  2121 . The LEDs  211  are mounted on the first surface  2121 , and electrically connected to the substrate  212 . 
         [0021]    The heat-dissipation device  22  is located on the second surface  2122 , and thermally connected to the substrate  212 . The heat-dissipation device  22  includes a plurality of cooling fins  221 , a hollow shell  223 , and an air impeller  225 , such as a fan. 
         [0022]    The cooling fins  221  are received in the hollow shell  223 . 
         [0023]    The hollow shell  223  includes a first side surface  223   a  and a second side surface  223   b . The second surface  223   b  is opposite to the first side surface  223   a . At least one inlet  222  is located on the first side surface  223   a ; and at least one outlet  224  on the second side surface  223   b . Further, the location of the at least one outlet  224  is higher than the location of the at least one inlet  222 . The air impeller  225  is located on the second side surface  223   b , and located below the outlet  224 . The airflow direction C generated by air impeller  225  is perpendicular to the airflow direction B of the heated air through the outlet  224 . 
         [0024]    The air impeller  225  exhausts the hot air along the airflow direction C thereof to effectively reduce air pressure in the hollow shell  223 . The cold air flows into the hollow shell  223  through the inlet  222 , and the convection loop is generated. 
         [0025]    Referring to  FIG. 4 , the illumination device  300  in accordance with a third embodiment of the disclosure, includes a light source  31  and a heat-dissipation device  32 . 
         [0026]    The light source  31  includes a plurality of LEDs  311  and a substrate  312 . The substrate  312  includes a first surface  3121  and a second surface  3122 . The second surface  3122  is opposite to the first surface  3121 . The LEDs  311  are mounted on the first surface  3121 , and electrically connected to the substrate  312 . 
         [0027]    The heat-dissipation device  32  is located on the second surface  3122 , and thermally connected to the substrate  312 . The heat-dissipation device  32  includes a plurality of cooling fins  321 , a hollow shell  323 , and an air impeller  325 , such as a fan. 
         [0028]    The cooling fins  321  are received in the hollow shell  323 . 
         [0029]    The hollow shell  323  includes a first side surface  323   a , a second side surface  323   b , and an upper surface  323   c . The second side surface  323   b  is opposite to the first side surface  323   a . The upper surface  323   c  is adjacent to the first side surface and the second surface  323   b . At least one inlet  322  is located on the first side surface  323   a ; and at least one outlet  324  on the upper surface  323   c . Optimally, the outlet  324  is located on the upper surface  323   c , away from the first side surface  323   a , and adjacent to the second side surface  323   b . In normal use, the upper surface  323   c  is higher than the first surface  323   a  and the second surface  323   b.    
         [0030]    The air impeller  325  includes a fan  3251  and an air-nozzle  3252 . The end of the air-nozzle  3252  adjacent to the outlet  324  is rectangular, and with a small cross-section area. The end of the air-nozzle  3252  which is adjacent to fan  3251  is columnar, conical, and with a large cross-section. The shape is recognized as providing optimum compression of air flowing therethrough, increasing the pressure difference between the inside and outside of the hollow shell  323 . Thus the heat-dissipation efficiency of the illumination device  300  is increased effectively. The fan  3251  is received in the air-nozzle  3252 . 
         [0031]    Referring to  FIG. 5 , the illumination device  400  in accordance with a fourth embodiment of disclosure includes a light source  41  and a heat-dissipation device  42 . 
         [0032]    The light source  41  includes a plurality of LEDs  411  and a substrate  412 . The substrate  412  includes a first surface  4121  and a second surface  4122 . The second surface  4122  is opposite to the first surface  4121 . The LEDs  411  are mounted on the first surface  4121 , and electrically connected to the substrate  412 . 
         [0033]    The heat-dissipation device  42  is located on the second surface  4122 , and thermally connected to the substrate  412 . The heat-dissipation device  42  includes a plurality of cooling fins  421 , a hollow shell  423 , and an air impeller  425 , such as a fan. 
         [0034]    The cooling fins  421  are received in the hollow shell  423 . 
         [0035]    The hollow shell  423  includes a first side surface  423   a , a second side surface  423   b , and an upper surface  423   c . The second side surface  423   b  is opposite to the first side surface  423   a . The upper surface  423   c  is adjacent to the first side surface  423   a  and the second side surface  423   b . Furthermore, at least one inlet  422  is located on the first side surface  423   a  and at least one outlet  424  on the upper surface  423   c.    
         [0036]    Optimally, the at least one outlet  424  is located on the upper surface  423   c , away from the first side surface  423   a , and adjacent to the second side surface  423   b . In normal use, the upper surface  423   c  is higher than the first side surface  423   a  and the second surface  423   b.    
         [0037]    The air impeller  425  includes a fan  4251  and a bellow-shaped air-nozzle  4252  configured for housing the fan  4251 . The air-nozzle has a gradually decreased diameter toward the outlet  424 . The bellow-shaped air-nozzle  4252  accelerates airflow therethrough, increasing pressure difference between the inside and outside of hollow shell  423 . The heat-dissipation efficiency of illumination device  400  is improved accordingly. 
         [0038]    While the disclosure has been described by way of example and in terms of exemplary embodiment, it is to be understood that the disclosure is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.