Abstract:
LEDs of a light matrix display are mounted between two metal frames. Each frame has air ducts to circulate air around the LEDs, thereby removing the heat generated in the LEDs and allowing higher intensity light to be emitted.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     This invention relates to light emitting diodes (LED), particularly to LED panels. 
     (2) Brief Description of Related Art 
     FIG. 1 shows a prior art LED matrix panel. Each LED is mounted on an insulating substrate  13  with bottom electrode bonded by connection  11  and the top electrode wire-bonded to connection  12  as shown in the side view FIG.  2 . The shortcoming of this kind of matrix panel is that there is no provision for heat removal. Such a structure is not suitable for high intensity display, which may cause overheating. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to provide ventilation for the LED matrix to prevent overheating. Another object of this invention is provide multi-color LED matrix display. 
     These objects are achieved by provide air ventilation through each LED. There are two metal frames spaced from each other. Each LED is mounted on one of the two metal frames. Each metal frame has air ducts, which surround the LEDs. The air ducts surround the LEDs to ventilate the LEDs 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWINGS 
     FIG. 1 shows the top view of a prior art LED matrix. 
     FIG. 2 shows the side view of FIG.  1 . 
     FIG. 3 shows the air ducts in the top metal frame of the present invention. 
     FIG. 4 shows the bottom metal frame, on which the LEDs are mounted. 
     FIG. 5 shows the stacking of the metal frames over an insulating substrate. 
     FIG. 6 shows a cross-section of metal frames surrounding a LED. 
     FIG. 7 shows spacers on the bottom metal frame of a second embodiment. 
     FIG. 8 shows wire-bonding of the top electrode of a LED to the common metal frame at a cross-point of a matrix of the second embodiment. 
     FIG. 9 shows wire-bonding of two LEDs at a cross-point of a matrix. 
     FIG. 10 shows pedestals on the bottom metal plate to be planar with the LED on the upper metal frame. 
     FIG. 11 shows the mounting of the LEDs with both bottom electrodes straddling over the structure in FIG.  10 . 
     FIG. 12 shows the cross-section of a LED mounted on the structure in FIG.  11 . 
     FIG. 13 shows the mounting of several LEDs straddling over two interdigital, horizontally placed, vented metal frames 
     FIG. 14 shows another embodiment of mounting several LEDs with alternate metal frames for the common first electrodes of the LEDs and the common second electrodes of the LEDs. 
     FIG. 15 shows Z-shape metal frames. 
     FIG. 16 shows wire-bonding of LEDs each with two top electrodes. 
     FIG. 17 shows focusing cups for each LED. 
     FIG. 18 shows focusing cup for LED with two bottom electrodes. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The basic idea of the present invention to package an array of LED matrix is to use two metal frames interposed with an insulating substrate. The first metal frame  22  is shown in FIG. 3 with larger air ducts  271  and smaller air vents  273 . The second metal frame  21 , as shown in FIG. 4, is mounted with LEDs  20  and air ducts  272  which are aligned with the air ducts  271  of the fist metal frames  271  on top. Each LED is surrounded by the smaller air duct  271  of the first metal frame  22 . 
     FIG. 5 shows the stacking of the two metal plates  22  and  21  interposed with a spacer insulating layer  23 . Note that each LED  20  of the matrix is surrounded by the smaller air duct  273 . The larger air ducts  271  do not surround any LED, but allow air to flow. The smaller air duct forms  273  a cup to focus the light emitted from the LED. 
     The cross-section view along the section line B-B′ in FIG. 5 is shown in FIG.  6 . The LED  20  is nested inside the air duct  273  and mounted on a second metal frame  21 . The LED has a bottom electrode contacting the lower metal frame  21  and a top electrode wire-bonded to the upper metal frame  22  by wire  24 . The larger air duct  271  of the fist metal frame  22  is aligned with the larger air duct  272  of the second metal frame  21 . The first metal frame  22  and the second (lower) metal frame  21  is separated by means of spacers  23 . Both the larger air ducts  271 ,  272  and the smaller air ducts  273  allow air to flow, thereby cooling down the LEDs  20 . 
     FIGS. 7 and 8 show the second embodiment of the present invention. FIG. 7 shows the top view of second metal frame  21 , showing the spacers  23 , LEDs  20  and the larger air ducts  272 . 
     FIG. 8 shows a second metal frame  22  lying over the metal frame  21 . In this structure, the first metal frame  22  has only large air ducts  271 , which are offset from the large air ducts  272  of the second metal frame  21 . The figure shows the top view of the first metal frame  22  stacking over the second metal frame  21 , which mounts the spacers  23  and the LEDs  20  at the cross-points of the ribs of the lower metal frame  21 . The air ducts  271  of the upper metal frames  22  and the air ducts  271  of the lower metal frames  21  are offset from each other to allow the top electrode of the LED  20  to be wire-bonded to the upper plate  22  by means of wire  24 . The bottom electrode of the LED is in contact with the lower metal frame  21 . 
     FIG. 9 shows a third embodiment of the present invention. Two LEDs  201  and  202  are placed at each the cross-point of the lower metal frame  21 . The two top electrodes of the two LEDs are both wire-bonded to the upper metal frame  22  by means of wires  24 . 
     FIG. 10 shows a fourth embodiment of the present invention. Pedestals are erected on the fist metal frame  22  so that the top electrode of each LED  20  mounted on the second metal frame  21  is planar with the top surface of the pedestal for easy wire-bonding. Spacers  23  are placed between the second metal frame and the pedestal. 
     FIG. 11 shows a fifth embodiment of the present invention. As in FIG. 10, the lower metal frame  22  has pedestals to be planar the upper metal frame  21 . Each LED has two bottom electrodes straddling between the pedestal and the metal frame  21 . The section-view along the section line C-C′ is shown in FIG.  12 . Note that the top surface of the metal frame  21  and the top surface of the pedestal of the lower metal frame  22  are planar with each other, and are separated by insulator  23 . 
     FIG. 13 shows a sixth embodiment of the present invention. The first metal frame  22  and the second metal frame  21  lie on the same horizontal plane interdigitally. Air ducts  271  are placed in the first metal frame  22  and air ducts  272  are placed in the second metal frame  21  for air circulation. LEDs  20  each with two bottom electrodes straddle across the two metal frames. 
     FIG. 14 shows a seventh embodiment of the present invention. The first metal frames  212 ,  214  with air ducts  272  and the second metal frames  211 ,  213  with air ducts  271  are placed alternately. One or more LEDs  201 ,  202 ,  203 ,  204  each with two bottom electrodes straddle across two adjacent metal frames. 
     FIG. 15 shows an eighth embodiment of the present invention. The first metal frame  22  and the metal frame  21  are formed in Z-shape. The first metal frame  22  has a larger air duct  271  and a smaller air duct  273 . The second metal frame  21  has an air duct  272  and is mounted with LEDs  20 . The upper edge of the Z-shaped first metal frame  22  stacks over the lower edge of the Z-shaped second metal frame with each air duct  273  surrounding over a LED  20  and allowing light to be transmitted. 
     FIG. 16 shows a ninth embodiment of the present invention for the matrix shown in FIG.  5 . When each LED  20  has both electrodes at the top surface, the two electrodes can be wire bonded by wires  241 ,  242  respectively to the first metal frame  22  and the second metal frames  21 . 
     FIG. 17 shows the tenth embodiment of the present invention. The first metal frame  22  for mounting the LED  20  is recessed as a cup to focus the light emitted from the LED  20 . The LED  20  shown in this figure has a bottom electrode contacting the first metal fame  22  and a top electrode wire-bonded by a wire  24  to the second metal frame  21 . 
     FIG. 18 shows an eleventh embodiment of the present invention. The LED  20  has two bottom electrodes straddling across the first metal frame  22  and the second metal frame  21 . The edges  252 ,  251  of the two metal frames are bent in the shape of a cup to focus the light emitted from the LED  20 . 
     While the preferred embodiments of the invention has been described, it will be apparent to those skilled in the art that various modifications may be made in the embodiments without departing from the spirit of the present invention. Such embodiments are all within the scope of this invention.