Abstract:
The present invention relates to a high-power LED array. The high-power LED array has a printed circuit board (PCB), anodes, cathodes, high-power LED dies, packing materials, and lenses. The PCB has cavities arranged in an array. One anode and one cathode are located in each cavity. The anode and the cathode are correspondingly connected to the anode and cathode in the neighboring cavities. At least one high-power LED die is placed in the cavity and connected to the anode and the cathode in series or in parallel. The cavity is filled with packing material to secure the high-power LED die. Lenses are placed on the cavities to focus light emitted by the high-power LED die.

Description:
RELATED APPLICATIONS  
       [0001]     The present application is based on, and claims priority from, Taiwan Application Serial Number 93127017, filed Sep. 7, 2004, the disclosure of which is hereby incorporated by reference herein in its entirety.  
       BACKGROUND  
       [0002]     1. Field of Invention  
         [0003]     The present invention relates a high-power Light Emitting Diode (LED). More particularly, the present invention relates to a high-power LED array.  
         [0004]     2. Description of Related Art  
         [0005]     A high-power LED array, such as a III-V high-power LED array, is frequently employed in outdoor display panels. Conventionally, packed high-power LEDs are assembled on a Printed Circuit Board (PCB) to form this type of high-power LED array.  FIG. 1  is a diagram illustrating the conventional high-power LED array. The high-power LED  100  includes an anode  101 , a cathode  102 , a high-power LED die  103 , and a lens  104 . The packed high-power LED  100  is connected to a PCB  110 .  
         [0006]     The high-power LED die  103  is placed in a cavity  106  of the cathode  102 . The high-power LED die  103  is electrically connected to the cathode  102 . The high-power LED die  103  is also electrically connected to the anode  101  via a wire  105 . The cavity  106  is then filled with packing material to secure the high-power LED die  103  in the cavity  106 . The packing material is also used as electrical isolation between the anode  101  and the cathode  102 . The lens  104  is placed on the anode  101  to focus light emitted by the high-power LED die  103 . After high-power LEDs  100  are all electrically connected to the PCB  110 , anodes  101  of the high-power LED  100  are electrically connected by anode wires  107 .  
         [0007]     However, several drawbacks arise for the conventional high-power LED array. First, when the high-power LED array is manufactured by assembling packed LEDs, the size of the LED array is usually bulky. Additional assembling procedures are required, and the manufacturing cost is therefore increased.  
         [0008]     Besides, optical misalignment is another issue concerned for the conventional high-power LED array. The optical misalignment results from the misalignment of the packed LED during the assembling procedures. The optical misalignment results in divergence and decreased light intensity. Since the lens inside the packed LED can&#39;t be adjusted, an additional external lens is usually required for re-focusing light emitted from the high-power LED array.  
         [0009]     Furthermore, inefficiency of heat dissipation is another disadvantage. Since the packed LED has a smaller surface area, the dissipation efficiency is compromised. The inefficiency of heat dissipation further degrades the light intensity of the high-power LED array.  
       SUMMARY  
       [0010]     It is therefore an objective of the present invention to provide a high-power LED array with decreased size, efficient heat dissipation, and improved optical alignment.  
         [0011]     It is another objective of the present invention to provide a high-power LED array packing method for packing a high-power LED array on a PCB.  
         [0012]     In accordance with the foregoing and other objectives of the present invention, a high-power LED array is provided. The high-power LED array includes a PCB, anodes, cathodes, high-power LED dies, packing material, and lenses. The PCB includes cavities arranged in an array. The cavity contains an anode and a cathode. The anodes are electrically connected. The cathodes are also electrically connected. At least one high-power LED die is located in the cavity. The high-power LED die is electrically connected to the anode and the cathode of the cavity in series or in parallel. The cavity is filled with packing material for securing the high-power LED die. A lens is placed on the cavity for focusing light emitted by the high-power LED die.  
         [0013]     According to another objective of the present invention, a high-power LED array packing method for packing a high-power LED array on a PCB is provided. The PCB includes cavities arranged in an array. The cavity contains an anode and a cathode. The anodes of the cavities are electrically connected. The cathodes of the cavities are also electrically connected. According to the high-power LED packing method of the present invention, at least one high-power LED die is first placed in the cavity. Next, the high-power LED die is electrically connected to the anode and the cathode of the cavity in series or in parallel. Further, the cavity is filled with packing material for securing the high-power LED die in the cavity. Finally, a lens is placed on the cavity to focus light emitted by the high-power LED die. The placement of the high-power LED die can be adjusted to optimize the light output.  
         [0014]     The high-power LED array according to the present invention has a significantly reduced size, and the efficiency of heat dissipation and the optical alignment are also improved. The placement of the lens on the cavity can be adjusted to optimize the light output. Further, the configuration of more than one high-power LED dies in the cavity enables the combination of high-power LED dies with different emission wavelengths in a single high-power LED array. The light intensity per unit area of the high-power LED array is also dramatically increased. Further, the high-power LED array packing method according to the present invention simplifies the packing procedures, increases the power-to-volume ratio, and reduces the manufacturing cost.  
         [0015]     It is to be understood that both the foregoing general description and the following detailed description are examples, and are intended to provide further explanation of the invention as claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:  
         [0017]      FIG. 1  is a cross-sectional diagram illustrating the conventional high-power LED array;  
         [0018]      FIG. 2  is a cross-sectional diagram illustrating the high-power LED array according to the first preferred embodiment of the present invention;  
         [0019]      FIG. 3  is a cross-sectional diagram illustrating the high-power LED array according to the second preferred embodiment of the present invention;  
         [0020]      FIG. 4  is a cross-sectional diagram illustrating the high-power LED array according to the third preferred embodiment of the present invention;  
         [0021]      FIG. 5  is a cross-sectional diagram illustrating the high-power LED array according to the fourth preferred embodiment of the present invention;  
         [0022]      FIG. 6  is a cross-sectional diagram illustrating the high-power LED array connecting to a secondary heat sink according to the present invention; and  
         [0023]      FIG. 7  is a flowchart illustrating the high-power LED array packing method according to the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.  
         [0025]     According to the high-power LED array of the present invention, the high-power LED dies are directly packed in the cavities of the PCB. The size of the high-power LED array can therefore be reduced dramatically. Further, the heat sink in the PCB also improves the efficiency of heat dissipation. Additionally, the placement of the lens on each cavity can be adjusted to optimize light output from the high-power LED array.  
         [0026]      FIG. 2  is a cross-sectional diagram illustrating the high-power LED array according to the first preferred embodiment of the present invention. The high-power LED array  200  according to the first preferred embodiment of the present invention includes a PCB  210 , anodes  220 , cathodes  230 , high-power LED dies  240 , heat sinks  250 , and lenses  260 .  
         [0027]     The PCB  210  includes cavities  211  arranged in an array. One or more high-power LED dies  240  are placed in the cavity  211 . More than one high-power LED dies  240  with the same emission wavelength, such as blue color high-power LED dies, can be placed in the cavity  211 . Alternatively, a combination of high-power LED dies  240  with different emission wavelength can be employed. For example, a combination of red, green, and blue color high-power LED dies  240  in the cavity  211  results in a white, high-power LED array.  
         [0028]     An anode  220  and a cathode  230  are inside the cavity  211 , and are electrically connected to the high-power LED dies  240  for providing power to the high-power LED dies  240 . The anode  220  and the cathode  230  of the cavity  211  are correspondingly connected in parallel to the anode  220  and the cathode  230  of the adjacent cavity  211 . The anode  220  and the cathode  230  are further connected to a common anode  221  and a common cathode  231 , respectively.  
         [0029]     The high-power LED dies  240  inside the cavity  211  are connected in series. As shown in the  FIG. 2 , the high-power LED dies  240  are placed on metal contacts  212  in the cavity  211 . All high-power LED dies  240  are electrically connected via the wire  213 , and are further connected to the anode  220  and the cathode  230  in the cavity  211 .  
         [0030]     Further, the PCB  210  includes heat sinks  250 . The heat sink  250  corresponds to each high-power LED die  240 , and is located underneath the metal contact  212 . The heat sink  250  is connected to the metal contacts  212  for conducting the heat generated by the high-power LED dies  240 . The heat sink  250  is further connected to a common heat sink  251 . The common heat sink  251  is located on the backside of the PCB  210  for providing larger dissipation area. The heat generated by the high-power LED dies  240  can be dissipated efficiently by the common heat sink  251 .  
         [0031]     After the high-power LED dies  240  are placed in the cavity  211  and electrically connected to the anode  220  and the cathode  230  via the wire  213 , he cavity  211  is filled with packing material for securing the high-power LED dies  240 . The packing material can be silicone or epoxy.  
         [0032]     Subsequently, the lens  260  is placed on the cavity  211  and bonded to the packing material. The placement of the lens  260  can be adjusted for respective cavity  211  to optimize light emitted from each cavity  211 .  
         [0033]      FIG. 3  is a cross-sectional diagram illustrating the high-power LED array according to the second preferred embodiment of the present invention. The high-power LED array  300  according to the second preferred embodiment of the present invention includes a PCB  310 , anodes  320 , cathodes  330 , high-power LED dies  340 , heat sinks  350 , and lenses  360 .  
         [0034]     The PCB  310  includes cavities  311  arranged in an array. One or more high-power LED dies  340  are placed in the cavity  311 . A plurality of one high-power LED dies  340  with the same emission wavelength, such as blue high-power LED dies, can be placed in the cavity  311 . Alternatively, a combination of high-power LED dies  340  with different emission wavelengths can be employed. For example, a combination of red, green, and blue color high-power LED dies  340  in the cavity  311  result in a white, high-power LED array.  
         [0035]     An anode  320  and a cathode  330  are inside the cavity  311 , and are electrically connected to the high-power LED dies  340  for providing power to the high-power LED dies  340 . The anode  320  and the cathode  330  of each cavity  311  are correspondingly connected to the anode  320  and the cathode  330  of the adjacent cavity  311  in parallel. The anode  320  and the cathode  330  are further connected to a common anode  321  and a common cathode  331 , respectively.  
         [0036]     The high-power LED dies  340  inside the cavity  311  are connected in parallel. As shown in the  FIG. 3 , the high-power LED dies  340  are placed on metal contacts  312  in the cavity  311 . Metal contacts  312  are electrically connected via the wire  313 , and the high-power LED dies  340  on both ends are further connected to the anode  320  and the cathode  330  in the cavity  311 .  
         [0037]     Further, the PCB  310  includes heat sinks  350 . The heat sink  350  corresponds to each high-power LED die  340 , and is located underneath the metal contact  312 . The heat sink  350  is connected to the metal contact  312  for conducting the heat generated by the high-power LED dies  340 . The heat sink  350  is further connected to a common heat sink  351 . The common heat sink  351  is located on the backside of the PCB  310  for providing a larger dissipation area. By the common heat sink  351 , the heat generated by the high-power LED dies  340  can be dissipated efficiently.  
         [0038]     After the high-power LED dies  340  are placed in the cavity  311  and electrically connected to the anode  320  and the cathode  330  via the wire  313 . The cavity  311  for securing the high-power LED dies  340  is filled with packing material. The packing material can be silicone or epoxy.  
         [0039]     Subsequently, the lens  360  is placed on the cavity  311  and bonded to the packing material. The placement of each lens  360  can be adjusted for respective cavity  311  to optimize light emitted from each cavity  311 .  
         [0040]     Further, the anodes and the cathodes of the adjacent cavities can also be electrically connected in series except for the parallel connection shown in the  FIG. 2  and  FIG. 3 .  FIG. 4  is a cross-sectional diagram illustrating a high-power LED array  400  according to the third preferred embodiment of the present invention. The PCB  410  includes a cavity  411   a  and a cavity  411   b . High-power LED dies  440   a  and  440   b  are placed on the metal contacts  412   a  and  412   b  in the cavities  411   a  and  411   b , respectively. The cavity  411   a  and  411   b  are electrically connected in series. The anode  420   a  is connected to a common anode  421 , while the cathode  430   b  is connected to a common cathode  431 . The adjacent cathode  430   a  and the anode  420   b  are connected in series. The high-power LED die  440   a  and  440   b  are connected in series via the wire  413   a  and  413   b , respectively. The metal contact  412   a  and  412   b  are connected to the heat sink  450   a  and  450   b , correspondingly. The heat sink  450   a  and  450   b  are further connected to a common heat sink  451  for conducting heat generated by the high-power LED die  440   a  and  440   b . The lens  460   a  and  460   b  are placed on the cavity  411   a  and  411   b  for focusing the light emitted by the high-power LED die  440   a  and  440   b , respectively.  
         [0041]      FIG. 5  is a cross-sectional diagram illustrating the high-power LED array  500  according to the fourth preferred embodiment of the present invention, where the cavities are electrically connected in series, and the high-power LED dies are electrically connected in parallel. The PCB  510  includes a cavity  511   a  and  511   b . High-power LED dies  540   a  and  540   b  are placed on the metal contacts  512   a  and  512   b  in the cavities  511   a  and  511   b , respectively. The cavities  511   a  and  511   b  are electrically connected in series. The anode  520   a  is connected to a common anode  521 , while the cathode  530   b  is connected to a common cathode  531 . The adjacent cathode  530   a  and the anode  520   b  are connected in series. The high-power LED dies  540   a  and  540   b  are connected in parallel via the wire  513   a  and  513   b . The metal contacts  512   a  and  512   b  are connected to the heat sinks  550   a  and  550   b , correspondingly. The heat sinks  550   a  and  550   b  are further connected to a common heat sink  551  for conducting heat generated by the high-power LED dies  540   a  and  540   b . The lens  560   a  and  560   b  are placed on the cavity  511   a  and  511   b  for focusing the light emitted by the high-power LED dies  540   a  and  540   b , respectively.  
         [0042]     Further, the high-power LED array according to the present invention can be connected to a secondary heat sink for enhancing the heat dissipation efficiency. As shown in the  FIG. 6 , the high-power LED array  200  illustrated in the  FIG. 2  is further connected to a secondary heat sink  270 . The common heat sink  251  of the high-power LED array  200  is secured to the secondary heat sink  270  via a thermal conductive adhesive  271 . The dissipation efficiency of the high-power LED array  200  can therefore be enhanced by the secondary heat sink  270 .  
         [0043]      FIG. 7  is a flowchart illustrating the high-power LED array packing method for packing a high-power LED array on a PCB according to the present invention. The PCB includes cavities arranged in an array. An anode and a cathode are placed inside the cavity. The anodes of the cavities are electrically connected, while the cathodes of the cavities are also electrically connected. According to the high-power LED array packing method of the present invention, one or more high-power LED dies are placed in the cavity (step  702 ). The high-power LED dies can be III-V high-power LED dies, and can have the same or different emission wavelengths. Next, the high-power LED dies are electrically connected to the anode and the cathode in the cavity (step  704 ). The high-power LED dies can be connected in series or in parallel via wires. Subsequently, the cavity is filled with packing material for securing the high-power LED dies in the cavity (step  706 ). The packing material can be silicone or epoxy. Then, a lens is placed on the cavity for focusing light emitted by the high-power LED dies. The placement of the lens can be adjusted to optimize the light output.  
         [0044]     The high-power LED array according to the present invention has a significantly reduced size, and the efficiency of heat dissipation and the optical alignment are also improved. The placement of the lens on the cavity can be adjusted to optimize the light output. Further, the configuration of more than one high-power LED dies in the cavity enables the combination of high-power LED dies with different emission wavelengths in a single high-power LED array. The light intensity per unit area of the high-power LED array is also dramatically increased. Further, the high-power LED array packing method according to the present invention simplifies the packing procedures, increases the power-to-volume ratio, and reduces the manufacturing cost.  
         [0045]     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.