Abstract:
The leads of a light emitting device package are extended is flexible pins. These pins can be bent with respect to a motherboard so that the direction of the light entitled from the light emitting device can be adjusted. The package is tab-mounted to the motherboard for heat sinking or serving as a lead.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of Invention 
     This invention relates to light emitting devices, particularly to the package of such devices. 
     (2) Brief Description of Related Art 
     FIG. 1 shows a prior art package for a light emitting device. The light emitting device  10  is mounted over a metal plate  11  with an extension to serve as the lead of the bottom electrode of the device  10 . The top electrode of the device  10  is wire-bonded by wire  13  to a second metal plate  12  with an extension to serve as the lead for the top electrode of the device. The structure is sealed in transparent glue as shown in the side-view FIG. 2 for protection and improvement in reliability. The bottoms of the metal plates  11 ,  12  can be soldered to a motherboard for surface-mounting. 
     The drawback of the kind of package is that the package is fixed to the motherboard so the light can only be emitted in a direction perpendicular to the motherboard. Also, the package does not have heat-sinking provision. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to provide a light emitting package capable of adjusting the direction of light emission. Another object of this invention is to provide a light emitting package capable of heat sinking. 
     These objects are achieved by extending the leads of the package into pin-shaped forks or thin-plate shaped forks. The number of leads can be two or more than two. The leads can be bent to emit light a desired direction. One of the leads is coupled to a tab for heat sinking. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 shows the top view a prior art surface-mount package for a light emitting device. 
     FIG. 2 shows the side view of FIG.  1 . 
     FIG. 3 shows the top-view of the basic fork-shaped leads of the present invention. 
     FIG. 4 shows the side-view of FIG.  3 . 
     FIG. 5 shows a top view of the package with two chips. 
     FIG. 6 shows the top view of the package for a chip with two top electrodes. 
     FIG. 7 shows the top view of the package for a chip with two bottom electrodes. 
     FIG. 8 shows the top view of the package for two chips each with two bottom electrodes. 
     FIG. 9 shows the package with the lead bent at right angle. 
     FIG. 10 shows the package with the lead bent at acute angle. 
     FIG. 11 shows the package with the lead folded. 
     FIG. 12 shows the package with the zigzag lead. 
     FIG. 13 shows the package with a focusing wall. 
     FIG. 14 shows the package with a stepped focusing wall. 
     FIG. 15 sows the package with a bevel focusing wall. 
     FIG. 16 shows the package with a transparent cover. 
     FIG. 17 shows the package with a transparent cover anchored in the stepped wall. 
     FIG. 18 shows the package with light emitting device mounted on a heat sinking tab. 
     FIG. 19 shows the package with one lead connected to the heat sinking tab. 
     FIG. 20 shows the leads lying on the same plane. 
     FIG. 21 shows the leads bent in different directions. 
     FIG. 22 shows the two leads bent in the same direction and a third lead in opposite direction. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 3 shows the basic structure of the present invention. A light emitting device chip  20  is mounted on metal substrate  22 . The electrodes of the chip are connected to pin-shaped leads  211 ,  212 ,  213  extending toward one side of the metal plate  22 . The middle lead  212  is continuous with the metal  22 , which is in contact with the bottom electrode of the chip  20 . The top electrode is wire-bonded-by wire  23  to the lead  211 . The lead  213  is unused. The chip, the bonding pads of the leads and the major portion of the metal plate  22  are sealed with transparent glue  25  to protect the combined structure and to stiffen leads  211 ,  212  and  213  in position. The leads can be bent so the direction of the light emitted from the chip can be adjusted. The opposite side of the metal plate  22  is extended outside the seal  25  to form a tab with a mounting hole  26 , which can be clamped by a screw to a motherboard to serve as a heat sink. 
     FIG. 4 shows the side view of FIG. 3, showing the chip  20  is wire-bonded to the lead  213  and sealed inside the glue  25 . 
     FIG. 5 shows two chips  20  and  202  mounted on the metal plate  22 . The bottom electrodes of the chips  20  and  202  are both in contact with the common lead  212 . The top electrode of the chip  20  is wire-bonded by wire  23  to lead  211 . The top electrode of the chip  202  is wire-bonded by wire  232  to the lead  213 . 
     FIG. 6 shows a chip  40  with two top electrodes. One top electrode is wire-bonded by wire  23  to lead  211 . The second top electrode is wire-bonded by wire  233  to the lead  212 . 
     FIG. 7 shows a chip  30  with two bottom electrodes straddling over the two leads  211  and  212 . 
     FIG. 8 shows two chips  30  and  302  each having two bottom electrodes. The chip  30  straddles over the leads  211  and  212 . The chip  301  straddles over the leads  212  and  213 . 
     FIG. 9 shows how the end  241  of a lead  21   x  as in FIG. 3 is bent in right angle to change the direction of light emission from the light emitting chip perpendicular to the motherboard, to which the leads are inserted. 
     FIG. 10 shows the how the end  241  of lead  21   x  is bent by an acute angle to change the direction of light emission from the light emitting chip at an acute angle with respect to the motherboard to which the leads are inserted. 
     FIG. 11 shows the ends of the leads  21   x  are folded at the end  243 . 
     FIG. 12 shows a zigzag lead  21   x . The bend  27  increase the imbedded area of the lead  21   x  in the, glue  25 , thereby strengthening the lead  21   x.    
     FIG. 13 shows the glue  25  forming a cup  28  over and surrounding the light emitting chips. The cup window exposes the light emitting device without being imbedded in the glue, thereby allowing more light transmission. The wall  28  of the cup can have a step as shown in FIG. 14, which is the side-view of FIG.  13 . The wall  28  of the cup may be beveled to form a focusing cup as shown in FIG.  15 . 
     FIG. 16 shows a transparent cover  45  mounted over the wall  28  of the cup  25  to protect the light emitting device. FIG. 17 shows a transparent cover  452  resting on the step of the wall shown in FIG. 14, and the glue  45  seals the structure outside the cover  452 . 
     FIG. 18 shows a structure in which the metal tab  32  is separated from the lead  312 . The chip is mount on the metal tab  32  serving as one lead for the bottom electrode of chip  20 , and the top electrode of the chip  20  is wire-bonded by wire  23  to the lead  311 . The tab  32  also serves as a heat sink by clamping the tab to a motherboard with a screw through the hole  26 . 
     FIG. 19 shows the metal tab  32  is continuous with a side lead  313  instead of a middle lead  312  shown in FIG.  3 . 
     FIG. 20 shows all three leads  211   a,    212   a  and  213   a  are in parallel. 
     FIG. 21 shows the three leads bent in different directions with leads  211   b  and  213   b  bent away from the middle lead  212   b.    
     FIG. 22 shows two the leads  211 C and  212 C bent in one direction and the lead  213 C bent in an opposite direction. 
     While the foregoing embodiments show only three leads, the number of leads is not limited to three leads. Two leads or more than three leads can be fabricated in a similar fashion. 
     While the preferred embodiments of the invention have 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 modifications are all within the scope of this invention.