Abstract:
A carrier structure for mounting at least an LED chip includes at least a lead and a base. The LED chip housed inside the base is coupled parallel with an electronic element. The lead is connected electrically to the LED chip at one end, while another end is exposed to the atmosphere. The base encaving the lead further has a shallow accommodation room to mount the electronic element at a surface not the same with the surface that mounts the LED chip.

Description:
This application claims the benefit of Taiwan Patent Application Serial No. 098210239, filed Jun. 9, 2009, the subject matter of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The invention relates to a carrier structure for mounting light-emitting diode (LED) chips, more particularly to the carrier structure that can provide superior shuttering protection for the LED chips mounted thereon. 
     (2) Description of the Prior Art 
     Various merits of a typical LED product can be found; such as a long service life, a reduced size, high vibration resistance, low heat generation, low energy consumption and so on. Hence, the LED products are widely applied to various indicators and light sources for household and/or workplace usage. Recently, the trend in the LED technology is moving toward color and high-illumination products, and the application of the LEDs has been extended to large-scaled outdoor displaying, traffic signaling and the like. It can be foreseen that the LED with its features in energy saving and green powering will definitely become the mainstream in future illumination industry. 
     However, the LED is vulnerable in usage. For example, the LED cannot sustain abnormal electric currents to flow by, and cannot afford to carry a higher electric voltage, either. Generally, while in facing those incidents, the LED would be broken so as to lead to a short circuit or an open circuit. 
     In the art, a protection circuit is usually used to protect the LED by paralleling to the LED chip. While in meeting an unexpected (high) surge voltage, the extra voltage will be shared by the protection circuit, and the LED chip in the parallel circuit can thus be saved. 
     Nevertheless, it would degrade the illumination efficiency of the LED chip if both the LED chip and the protection circuit are constructed close to each other at the same bonding surface. Referring to  FIG. 1 , a typical LED packaging is shown. The package to mount the LED chip  20  includes a housing  40  and a lead frame  30 . The LED chip  20  wired to the lead frame  30  is laid on the housing  40  in a concave room thereof. The protection circuit  50  also laid in the concave room and wired to the lead frame is arranged neighborly to the LED chip  20 . It is noted that the LED chip  20  and the protection circuit  50  are posed in an electric parallel relationship in the package of  FIG. 1 . 
     By providing the arrangement of the LED chip  20  and the protection circuit  50  in the package as shown in  FIG. 1 , a shuttering effect would be formed to degrade the illumination of the LED chip  20 . Moreover, the illumination pattern of the LED chip  20  might be altered to some extent. An alternative to the design of  FIG. 1  is shown in  FIG. 2 , in which the protection circuit  50  is located under the LED chip  20  by being buried into the housing  40 ′. However, though the shuttering problem of the design in  FIG. 1  might be resolved by the design of  FIG. 2 , yet the cost for this change would be considerable and yield of the package of  FIG. 2  would be lower by compared to that of  FIG. 1 . 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a carrier structure for mounting LED chips, by which the mounting surface of the LED chips can differ from that of other electronic elements; such that the aforesaid shuttering problem can be reduced to a minimum, a cost hike for providing the LED assembly can be avoided, and the yield thereof can be ensured. 
     In the present invention, the carrier structure for mounting LED chips can include at least a lead and a base. The base laying out the lead is to mount the LED chip. One end of the lead is coupled with the LED chip, while another end to expose to the base. 
     The base further includes a reflection bowl structure for concentrating lights emitted by the LED chip that centers the reflection bowl structure. 
     The base can further include a heat-dissipating block and an insulation base. The insulation base accommodates part of the heat-dissipating block, which the heat-dissipating block extends inward from the outsides of the base to bear thereon the LED chip. 
     In the present invention, an accommodation room of the base is to locate a respective electronic element coupled with the LED chip, in which the electronic element can be part of a driving unit or a protection circuit. 
     All these objects are achieved by the carrier structure for mounting LED chips described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be specified with reference to its preferred embodiment illustrated in the drawings, in which: 
         FIG. 1  is a schematic cross-sectional view of a typical LED packaging in the art; 
         FIG. 2  is a schematic cross-sectional view of another LED packaging in the art; 
         FIG. 3  is a perspective view of a first embodiment of the carrier structure for mounting LED chips in accordance with the present invention; 
         FIG. 4  shows the base of  FIG. 3 ; 
         FIG. 4A  shows the lead and the heat-dissipating block of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of  FIG. 3  along line AA; 
         FIG. 6  is a perspective view of a second embodiment of the carrier structure in accordance with the present invention; and 
         FIG. 7  is a cross-sectional view of  FIG. 6 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention disclosed herein is directed to a carrier structure for mounting LED chips. In the following description, numerous details are set forth in order to provide a thorough understanding of the present invention. It will be appreciated by one skilled in the art that variations of these specific details are possible while still achieving the results of the present invention. In other instance, well-known components are not described in detail in order not to unnecessarily obscure the present invention. 
     Referring now to  FIG. 3 ,  FIG. 4 ,  FIG. 4A  and  FIG. 5 , a perspective view of a first embodiment of the carrier structure  1  in accordance with the present invention, a perspective view of a base  4  of the carrier structure  1 , a perspective view of leads  3  and a heat-dissipating block  43  of the carrier structure  1 , and a cross-sectional view of  FIG. 3  along line AA are shown, respectively. The carrier structure  1  includes at least one conductive lead  3  (six leads  3  shown in the figures) and one base  4 . It is noted that in  FIG. 5  one LED chip  20  and one electronic element  50  are additionally included to demonstrate respective occupations in the carrier structure  1 . 
     The base  4  provides relevant empties to house the leads  3  in a radiant pattern. One end of any lead  3  is connected with an LED chip  20  located in middle of the base  4 , while the other end thereof is extended outward so as to further connect to a printed circuit board (not shown herein). 
     The base  4  has an accommodation room  5  for containing an electronic element  50  at an upper portion of the base  4 , preferably at the middle upper portion thereof. As shown in  FIG. 5 , for the LED chip  20  is located strictly above the electronic element  50 , such that the concerned shuttering effect upon the LED chip  20  by the electronic element  50 , leading to degrade the illumination of the LED chip  20  and distort the illumination pattern, can be thoroughly resolved. 
     The base  4  further includes a lower insulation base  41 , an upper bottom-off reflection bowl structure  42  and a heat-dissipating part  43 . The insulation base  41  can be made of a plastics and the like. The reflection bowl structure  42  can be made of a metallic material, such as aluminum, silver, and any material that can form a light-reflection interior surface. Alternative, the reflection bowl structure  42  can be made of a plastic material coated interiorly a metallic reflection layer. As shown in  FIG. 3 , the accommodation room  5  is located on the insulation base  41  but under the bottom-off reflection bowl structure  42 . 
     The heat-dissipating part  43  is made of a heat-conductive material; such as a metal, a metal alloy, a ceramic material, or any material that presents acceptable heat-dissipation properties. In the present invention, the heat-dissipating part  43  and the leads  3  can be made of the same material. By providing an adequate pathway design in the insulation base  41  as shown in  FIG. 4 , the insulation part  42  can be arranged to be encaved in a lower portion of the insulation base  41  with one end thereof exposed to the atmosphere, a middle portion thereof exposed to the bottom area of the bottom-off reflection bowl structure  42  so as to sustain thereon the LED chip  20  and the electronic element  5 , and another end thereof extended further to be exposed to the atmosphere opposing to said one end. It is noted from  FIG. 3  and  FIG. 5  that said middle portion of the heat-dissipating part  43  is formed as a step structure so as to have this end structured to provide a wall to the accommodation room  5  and a platform protrusion  431  to uphold the electronic material  50  in the accommodation room  5 . The platform protrusion  431  is preferably extended to be said another end of the heat-dissipating part  43 . By providing the heat-dissipating part  43  of the present invention, heat generated by the LED chip  20  and the electronic element  50  can be forwarded all the way along the heat-dissipating part  43  to dissipate into the atmosphere. 
     In the present invention, the insulation base  41  and the reflection bowl structure  42  can be integrally formed as a unique piece, as shown in  FIG. 4 . It is also clearly seen the pathway design in the insulation base  41 , which is there to receive the leads  3  and the heat-dissipating part  43 . 
     As shown in  FIG. 4A , the leads  3  and the heat-dissipating part  43  further have their own configuration stops  31  and  432 , respectively, to help the leads  3  and the heat-dissipating part  43  engaged into the insulation base  41 . Also, the step structure in the middle portion of the heat-dissipating part  43  is clearly demonstrated at the right portion of the heat-dissipating part  43 , viewed from  FIG. 4A . 
     As shown in  FIG. 5 , the LED chip  20  is coupled with the leads  3  through properly wiring  60 . The electronic element  50  located in the accommodation room  5  can be a drive chip or a protection circuit. In the case that the electronic element  50  is a protection circuit, the voltage across the electronic element  50  should be larger than that across the LED chip  20 . 
     Referring now to  FIG. 6 , a perspective view (an upside down view by compared to  FIG. 3 ) of a second embodiment of the carrier structure in accordance with the present invention is shown. The difference between this embodiment and the first embodiment shown from  FIG. 3  through  FIG. 5  is that in this second embodiment the accommodation room  5  for containing the electronic element  50  is formed at the lower portion of the insulation base  41  (i.e., the portion away from the reflection bowl structure  42 ) and is exposed to the bottom of the insulation base  41 . Namely, in application of the second embodiment, the electronic element  50  in the accommodation room  5  is mounted under the heat-dissipating part  43 , by compared to the above the heat-dissipating part  43  in the first embodiment. 
     Referring now to  FIG. 7 , a cross sectional view of  FIG. 6 , at an angle which is compared to the viewing angle of  FIG. 5 , is shown. As described above, the major difference between the first embodiment in  FIG. 3  and the second embodiment in  FIG. 6  is the location of the accommodation room  5  for nesting the electronic element  50 . This major difference is clearly shown in  FIG. 7 . As shown, the accommodation room  5  of this second embodiment is located at the lower portion of the insulation base  41  and exposed to the atmosphere. With respect to the heat-dissipating part  43 , the electronic element  50  is mounted under the bottom surface of the platform protrusion  431 , such that the heat generated by the electronic element  50  can be dissipated through the heat-dissipating part  43 . 
     In practice, the products shown in  FIG. 5  and  FIG. 7  can be further encapsulated as a unique device. 
     In the invention, by providing sufficient leads  3  and space in the reflection bowl structure, the carrier structure  1  can be used to mount a limited number of the LED chips  20  for accounting to different or various wavelength lights. For example in  FIG. 5  or  FIG. 7 , three LED chips accounted for a red light LED, a blue light LED and a yellow light LED can be planted to the six leads  3  provided in the carrier structure  1 . 
     By providing the accommodation room  5  for mounting the electronic element  50  separated from the space for mounting the LED chip  20  in accordance with the present invention, the aforesaid shuttering effect caused in between to the conventional structure as shown in  FIG. 1  and  FIG. 2  can be reduced to a minimum, without sacrificing the manufacturing cost and the yield. 
     While the present invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be without departing from the spirit and scope of the present invention.