Heat dissipation device for led chips

Abstract

A heat dissipation device for removing heat from LED chips includes a finned heat sink, a plurality of heat pipes and a plurality of heat conductive substrates. The heat sink comprises a base plate and a plurality of fins formed on the base plate. The heat pipes which transfer heat in a unidirectional manner are embedded in the base plate. Each of the heat pipes defines a first wall and a second wall coupled to the heat sink. The heat pipes only transfer heat from the first walls to the second walls and restrict a heat transfer in a reversed direction. The substrates are in contact with first walls of the heat pipes. The LED chips are mounted on the substrates. When the LED chips generate heat, the heat is transferred to the fins via the unidirectional heat pipes to lower the temperature of the LED chips.

1 . A heat dissipation device adapted for removing heat from LED chips, comprising:
 a heat sink comprising a base plate which defines a first surface and a second surface opposite to the first surface, and a plurality of fins formed on the second surface of the base plate;   a plurality of heat pipes of unidirectional heat transfer being embedded in the first surface of the heat sink, each of the heat pipes defining a first wall and a second wall coupled to the heat sink, the heat pipes only transferring heat from the first walls to the second walls and restrict a heat transfer in a reversed direction; and   a plurality of substrates in contact with first walls of the heat pipes, and the LED chips being mounted on the substrates;   wherein when the LED chips generate heat, the heat is transferred to the fins via the unidirectional heat pipes to lower a temperature of the LED chips.   
   
   
       2 . The heat dissipation device as claimed in  claim 1 , wherein each of the heat pipes is provided with a capillary wick which has one of the following structures: a plurality of fine grooves defined in a lengthwise direction of the casing, a fine-mesh wick, or a layer of sintered metal/ceramic powders only formed on an inner side of the first wall and away from the second wall. 
   
   
       3 . The heat dissipation device as claimed in  claim 2 , wherein the heat pipes each are half filled with working liquid which is just enough to submerge the capillary wick adjacent to the first wall when the first wall faces downwardly toward the ground. 
   
   
       4 . The heat dissipation device as claimed in  claim 1 , wherein each of the substrates is a flat plate and defines a first surface on which the LED chips are mounted and a second surface opposite to the first surface. 
   
   
       5 . The heat dissipation device as claimed in  claim 4 , wherein the second surfaces of the substrates are coupled to the first surface of the heat sink and the first walls of the heat pipes. 
   
   
       6 . The heat dissipation device as claimed in  claim 1 , wherein the heat pipes each can be one of various shapes: straight, L-shaped, U-shaped and S-shaped, and the first surface of the heat sink defines corresponding receiving grooves accommodating the heat pipes therein. 
   
   
       7 . The heat dissipation device as claimed in  claim 6 , wherein the heat pipes each are straight and are juxtaposed closely to each other and respectively received in the corresponding straight receiving grooves. 
   
   
       8 . The heat dissipation device as claimed in  claim 1 , wherein the fins extend from the second surface of the base plate and can be constructed in various configurations to maximize a heat-exchanging area of the heat sink. 
   
   
       9 . A heat dissipation device adapted for removing heat from LED chips, comprising:
 a finned heat sink comprising a base plate;   a plurality of heat pipes embedded in the base plate, each heat pipe comprising a casing which is half filled with working liquid and has a first wall and a second wall in contact with the base plate of the heat sink; and   a plurality of heat conductive substrates each defining a first surface on which the LED chips are mounted and a second surface in contact with the heat pipes;   wherein each of the heat pipes is provided with a capillary wick which has one of following structures: a plurality of fine grooves defined in a lengthwise direction of the casing, a fine-mesh wick, or a layer of sintered metal/ceramic powders only formed on an inner side of the first wall and away from the second wall, and working liquid which is just enough to submerge the capillary wick adjacent to the first wall when the first wall faces downwardly toward the ground.   
   
   
       10 . The heat dissipation device as claimed in  claim 9 , wherein the substrates each are a flat plate, the second surfaces of the substrates are coupled to the base plate of the heat sink and the first walls of the heat pipes, a major part of the second surfaces of the substrates being in contact with the first walls of the heat pipes. 
   
   
       11 . The heat dissipation device as claimed in  claim 10 , wherein the heat pipes each can be one of various shapes: straight, L-shaped, U-shaped and S-shaped, and the first surface of the heat sink defines corresponding receiving grooves accommodating the heat pipes therein. 
   
   
       12 . The heat dissipation as claimed in  claim 10 , wherein the heat pipes are straight and divided into two groups, and each group of the heat pipes are connected with at least two substrates. 
   
   
       13 . The heat dissipation device as claimed in  claim 12 , wherein the heat pipes of each group are juxtaposed closely to each other and respectively received in the corresponding straight receiving grooves. 
   
   
       14 . The heat dissipation as claimed in  claim 9 , wherein the base plate defines a first surface coupled with the second surfaces of the substrates and a second surface opposite to the first surface, and a plurality of fins are formed on the second surface of the base plate. 
   
   
       15 . An LED assembly comprising:
 a heat sink having a plurality of fins thereon;   a plurality of heat pipes embedded in the heat sink;   a plurality of heat conductive substrates coupled to the heat pipes; and   a plurality of LED chips mounted on the substrates;   wherein the heat pipes allow heat generated by the LED chips to be transferred to the heat sink via the substrates and the heat pipes, and inhibit heat in the heat sink to be transferred to the substrates via the heat pipes.