Abstract:
The present invention discloses a light-emitting diode packaging structure, comprising a base; a chip; a first material disposed on at least one side of the chip and having a first refraction index; a second material disposed upon the chip, having a second refraction index, and separated with the first material with an interface therebetween to refract the light refracted from the first material; and a ball lens disposed upon the second material and forming a confined space with the base; whereby, the light emitted from the chip refracts through the first refraction material and the second refraction material and finally emits out from the ball lens.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a light-emitting diode packaging structure, and in particular to a light-emitting diode packaging structure which can enhance the luminescent efficiency of light-emitting diodes. 
       BACKGROUND OF THE INVENTION 
       [0002]    The modern light-emitting diode (LED) industry has been striving to enhance LED&#39;s luminescent efficiency, which is determined by the following factors: (1) the luminescent efficiency of LED chip, including the internal efficiency which involves transforming internal electric energy into light energy in the LED chip, and the external efficiency which involves the light emitted from the chip interior to its exterior; (2) the light conversion efficiency of phosphor (if necessary); for example, the most common commercial white LED packaging structure employing blue light chip and yellow phosphor; and (3) the design of packaging structure, most of which stresses the choice of transparent materials, such as high light transmittance, high penetrability, high refractivity, high heat dissipating materials, the structural design (high-power LED), and so on. 
         [0003]    From the perspective of optics, the LED industry has the following options to increase the luminescent efficiency: (1) using transparent or translucent substrate for LED chip, for example blue-green light chip of sapphire or SiC substrate, red-yellow GaP substrate, and so on; (2) enhancing the light emitting efficiency of the emission area of LED, increasing the roughness of the emission zone, for example; and (3) employing packaging materials with high light transmittance, high penetrability, and high refractivity. 
         [0004]      FIG. 1  illustrates the light refraction path of a conventional surface-mount (SM) LED and  FIG. 2  illustrates the light refraction path of a conventional direct in-line (DIP) LED. With reference to the figures, light emitted from the LED (or the phosphor layer) comprises front radiation  21  from its front surface and side radiation  22  and  23  from its sides. However, the side radiations  22  and  23  have to be inflected/refracted inside the packaging interior of the LED before emitting outside. The light path is long and the intensity of the light will be diminished as a result of absorption by the LED packaging materials. Furthermore, the final emitted light (light  31  and  32  denoted in  FIG. 2 ) is no longer the target light originally designed before LED packaging. 
         [0005]    For the optics of the LED packaging, the design of LED luminescent angle is important, apart from choosing packaging materials with high light transmittance, high penetrability, and high refractivity. The inadequate design of the luminescent angle of the LEDs shown in  FIGS. 1 and 2  leads to poor luminescent efficiency, which is a drawback remained to be improved. 
         [0006]    The present invention discloses a LED packaging structure to overcome the drawback of the design of the conventional LED packaging structure. 
       SUMMARY OF THE INVENTION 
       [0007]    One objective of the present invention is to provide a light-emitting diode (LED) packaging structure which employs two materials with different refraction indexes to refract the light emitted from a chip and then emit out through a ball lens to enhance the luminescent efficiency of LEDs. 
         [0008]    To achieve the aforementioned objective, the present invention provides a light-emitting diode packaging structure, comprising a base disposed with a positive connection pad and a negative connection pad; a chip disposed on the base and coupled with the positive and negative connection pads with two conducting wires, respectively; a first material disposed on at least one side of the chip and having a first refraction index to refract the light emitted from the chip; a second material disposed upon the chip, having a second refraction index, and separated with the first material with an interface therebetween to refract the light refracted from the first material; and a ball lens disposed upon the second material and forming a confined space with the base; consequently, the light emitted from the chip refracts through the first refraction material and the second refraction material and finally emits out from the ball lens. 
         [0009]    To achieve the aforementioned objective, the present invention provides a light-emitting diode packaging structure, comprising a base disposed with a first leg; a second leg disposed on one side of the base; a chip disposed on the base and coupled with the first leg and the second leg with two conducting wires, respectively; a first material disposed on at least one side of the chip and having a first refraction index to refract the light emitted from the chip; a second material disposed upon the chip, having a second refraction index, and separated with the first material with an interface therebetween to refract the light refracted from the first material; and a ball lens disposed upon the second material and forming a confined space with the base, the first leg, and the second leg; whereby, the light emitted from the chip refracts through the first refraction material and the second refraction material and finally emits out from the ball lens. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The present invention can be more fully understood by reference to the following description and accompanying drawings, in which: 
           [0011]      FIG. 1  illustrates the light refraction path of a conventional surface-mount (SM) light-emitted diode (LED); 
           [0012]      FIG. 2  illustrates the light refraction path of a conventional direct in-line (DIP) LED; 
           [0013]      FIG. 3  illustrates the cross-sectional view of a LED packaging structure according to the present invention; and 
           [0014]      FIG. 4  illustrates the cross-sectional view of another preferred embodiment of a LED packaging structure according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0015]      FIG. 3  illustrates the cross-sectional view of a light-emitted diode (LED) packaging structure according to the present invention. 
         [0016]    With reference to  FIG. 3 , a LED packaging structure  100  according to the present invention is, for example but not limited to, a surface-mount LED, comprising a base  110 , a chip  120 , a first materials  130 , a second material  140 , and a ball lens  150 . 
         [0017]    The base  110  is disposed with a positive connection pad  111  and a negative connection pad  112  to be coupled with a printed circuit board (not shown). The base  110  is conventional art of a LED packaging structure. It is not the focus of the present invention and therefore will not be discussed hereafter. 
         [0018]    The chip  120  is disposed upon the base  110  and coupled with the positive connection pad  111  and the negative connection pad  112  with two conducting wires  121  and  122 , respectively, wherein the chip  120  may emit required electroluminescent light of different colors, which is a conventional are and will not be discussed hereafter. 
         [0019]    The chip  120  is disposed with the first material  130  at least on its one side, for example but not limited to two sides, which has a first refraction index N 12  to refract or reflect the light  123  and  124  emitted from the chip  120 , wherein the first material  130  is, for example but not limited to, air or an opaque material, which is, for example but not limited to, opaque epoxy resin, to refract the electroluminescent light emitted from the chip to the second material  140  in a proper angle. 
         [0020]    The second material  140  is disposed upon the chip  120 , has a second refraction index N 13 . Furthermore, the second material  140  is separated with the first material  130  by an interface  135  to further refract the light  123  and  124  refracted from the first material  130  such that the light may emit nearly perpendicularly out from the ball lens  150  and in turn shorten the light path from the chip  120  as well as enhance the luminescent efficiency. The first refraction index N 12  of the first material  130  is lower than the second refraction index N 13  of the second material  140 . Furthermore, the interface  135  is, for example but not limited to, an oblique surface, a curve, or a curved surface and the included angle θ between the interface  135  and the base  110  is, for example but not limited to, 10°˜90°, preferably 40°˜50°. 
         [0021]    The ball lens  150  is disposed upon the second material  140  and forms a confined space with the base  110  to protect the base  110 , the chip  120 , the first material  130 , and the second material  140 . The arrangement is a conventional art and will not be discussed hereafter. 
         [0022]    Also, the chip  120  according to the present invention is further disposed with phosphor  160  on its top, which may convert the light emitted from the chip  120  to a desired color. The phosphor  160  has the function of light conversion, which can convert the light  123  and  124  emitted from the chip  120  to a desired color, which is a conventional art and will not be discussed hereafter. 
         [0023]    Consequently, with the LED packaging structure  100  according to the present invention, the light  123  and  124  emitted from the chip  120  refracts through the first material  130  and refracts again through the second material  140  such that the light may emit out nearly perpendicularly from the ball lens  150  and in turn shorten the light path of the light  123  and  124  from the chip  120  as well as enhance luminescent efficiency. 
         [0024]      FIG. 4  illustrates the cross-sectional view of another preferred embodiment of a LED packaging structure according to the present invention. 
         [0025]    With the reference to  FIG. 4 , a LED packaging structure  200  according to the present invention is, for example but not limited to, a direct in-line LED, comprising a base  210  disposed with a first leg  215 , a second leg  216 , a chip  220 , a first materials  230 , a second material  240 , and a ball lens  150 . 
         [0026]    The base  210  is disposed with a first leg  215 , which is, for example but not limited to, a positive leg, to be coupled with a printed circuit board (not shown). The base  210  is conventional art of a common LED packaging structure. It is not the focus of the present invention and therefore will not be discussed hereafter. 
         [0027]    The second leg  216  is disposed on one side of the base  210  and is, for example but not limited to, a negative leg to be coupled with a printed circuit board (not shown). The first leg  215  and the second leg  216  are conventional art of a common LED packaging structure and therefore will not be discussed hereafter. 
         [0028]    The chip  220  is disposed upon the base  210  and coupled with the first leg  215  and the second leg  216  by two conducting wires  221  and  222 , respectively, wherein the chip  220  may emit required electroluminescent light of different colors, which is a conventional art and will not be discussed hereafter. 
         [0029]    The chip  220  is disposed with the first material  230  at least on its one side, for example but not limited to two sides, which has a first refraction index N 22  to refract or reflect the light  223  and  224  emitted from the chip  220 , wherein the first material  230  is, for example but not limited to, air or an opaque material, which is, for example but not limited to, opaque epoxy resin, capable of refracting the electroluminescent light  223  and  224  emitted out from the chip to the second material  240  in a proper angle. 
         [0030]    The second material  240  is disposed upon the chip  220  and has a second refraction index N 23 . The second material  240  is separated with the first material  230  by an interface  235  to further refract the light  223  and  224  refracted from the first material  230  such that the light may emit out nearly perpendicularly from the ball lens  250  and in turn shorten the light path from the chip  220  as well as enhance luminescent efficiency. The first refraction index N 22  of the first material  230  is lower than the second refraction index N 23  of the second material  240 . Furthermore, the interface  235  is, for example but not limited to, an oblique surface, a curve, or a curved surface and the included angle θ between the interface  235  and the base  210  is, for example but not limited to, 10°˜90°, preferably 40°˜50°. 
         [0031]    The ball lens  250  is disposed upon the second material  240  and forms a confined space with the base  210  to protect the base  210 , the chip  220 , the first material  230 , and the second material  240 . The arrangement is a conventional art and will not be discussed hereafter. 
         [0032]    Also, the chip  220  according to the present invention is further disposed with phosphor  260  on its top, which may convert the light emitted from the chip  220  to a desired color. The phosphor  260  has the function of light conversion, which can convert the light emitted from the chip  220  to a desired color, which is a conventional art and will not be discussed hereafter. 
         [0033]    Consequently, with the LED packaging structure  200  according to the present invention, the light  223  and  224  emitted from the chip  220  refracts through the first material  230  and refracts again through the second material  240  such that the light may emit out nearly perpendicularly from the ball lens  250  and in turn shorten the light path of the light  223  and  224  from the chip  220  as well as enhance the luminescent efficiency. 
         [0034]    Consequently, with the implementation of a LED packaging structure according to the present invention, two materials with different refraction indexes to refract the light emitted from a chip and then emit out through a ball lens to enhance the luminescent efficiency of LEDs to overcome the drawbacks of conventional LED packaging structure. 
         [0035]    It is appreciated that although the directional practice device of the present invention is used in a very limited space instead of practicing at the real playing field, effective and steady practice can be obtained as well. Further, it is very easy to set up and to operate the directional practice device of the present invention. These advantages are not possible to achieve with the prior art. 
         [0036]    While the invention has been described with reference to the a preferred embodiment thereof, it is to be understood that modifications or variations may be easily made without departing from the spirit of this invention, which is defined by the appended claims.