Patent Publication Number: US-2013234183-A1

Title: Led module

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure generally relates to light sources, and particularly to a light emitting diode (LED) module having good light output efficiency. 
     2. Description of Related Art 
     LEDs have many advantages, such as high luminosity, low operational voltage, low power consumption, compatibility with integrated circuits, faster switching, long term reliability, and environmental friendliness which have promoted their wide use as a light source. 
     A conventional LED generally generates a smooth round light field with a radiation angle of 114 degrees. The light emitted from the LED is mainly concentrated at a center thereof. The light at a periphery of the LED is relatively poor and can not be used to illuminate. Therefore, light output efficiency of the conventional LED is decreased. 
     What is needed therefore is an LED which can overcome the above mentioned limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the disclosure. 
         FIG. 1  is an exploded, cross-sectional view of an LED module according to an exemplary embodiment of the present disclosure. 
         FIG. 2  is an assembled view of the LED module of  FIG. 1 . 
         FIG. 3  is a schematic view showing light paths of the LED module of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the drawings to describe the present LED module  1 , in detail. 
     Referring to  FIG. 1  and  FIG. 2 , the LED module  1  includes an LED  10  and a lens  40  matching with the LED  10 . 
     The LED  10  includes a substrate  11 , a first electrode  12 , a second electrode  13 , an LED chip  14  and an encapsulant  15 . The substrate  11  is flat. The first electrode  12  and the second electrode  13  are arranged on a top surface of the substrate  11  and spaced from each other. The LED chip  14  is mounted on a top surface of the first electrode  12 . The LED chip  14  is electrically connected to the first electrode  12  and the second electrode  13  via metal wires  141 , respectively. The encapsulant  15  encapsulates the LED chip  14  therein. The encapsulant  15  is made by epoxy, silicon, glass or other transparent materials which have good light-permeable and water-proof capabilities. In this embodiment, a plurality of fluorescent powder  151  may be doped within the encapsulant  15  to adjust the color of the light emitted from the LED chip  14 . 
     The lens  40  covers the encapsulant  15  and the LED chip  14  to change the path of the light emitted from the LED chip  14 , thereby improving the utilization rate of the light. The lens  40  is made of a transparent material with a good optical performance, such as PMMA (polymethyl methacrylate), PC (Polycarbonate) plastic. The lens  40  is symmetrical with respect to a virtual central axis O-O′ line (as shown in  FIG. 2 ). 
     The lens  40  includes a light-guiding portion  41 , a rough portion  43  and a pair of retaining portions  45 . 
     The light-guiding portion  41  includes a curved top surface  415 , a flat bottom surface  411  and an annular side surface  413  interconnecting edges of the top surface  415  and the bottom surface  411 . A width of the top surface  415  along a direction parallel to the top surface of the substrate  11  is larger than that of the bottom surface  411 . The side surface  413  is inclined, and extends downwardly and inwardly from an edge of the top surface  415  to a corresponding edge of the bottom surface  411 . The top surface  415  is employed as a light-emergent surface of the LED module  1 . Most of the light emitted from the LED  10  penetrates the lens  40  from the top surface  415 , and another part of the light penetrates the lens  40  from the side surface  413 . 
     The top surface  415  includes a pair of first curved surfaces  4151  cooperatively forming a wing-shaped configuration. The first curved surfaces  4151  are symmetrical about the virtual central axis  0 - 0 ′ line. Each of the first curved surfaces  4151  is convex. Outer edges of each first curved surface  4151  respectively connect a top edge of the side surface  413 . Inner edges of the two first curved surfaces  4151  intersect at a joint  4153 . The joint  4153  is located on the virtual central axis O-O′ line. A distance between each first curved surface  4151  and the bottom surface  411  of the light-guiding portion  41  is decreased from a central portion of the first curved surface  4151  to a periphery of the first curved surface  4151 . 
     A cavity  417  is recessed from a central portion of the bottom surface  411  to receive the LED chip  14  therein. The cavity  417  is surrounded by a second curved surface  4171  and an annular surface  4173  connecting the second curved surface  4171 . The second curved surface  4171  is convex to form a dome. The center of the second curved surface  4171  is aligned with the joint  4153 . The annular surface  4173  is perpendicular to the substrate  11 . The second curved surface  4171  and the annular surface  4173  is employed as a light input surface of the lens  40 . A width of the cavity  417  along the direction parallel to the top surface of the substrate  11  equals that of the encapsulant  15 . 
     A reflecting layer  4131  is filmed to an inner surface of the side surface  413  to reflect a part of the light radiated towards the side surface  413  to make the reflected light radiate through the top surface  415  of the light guiding portion  41  to enhance a light output efficiency of the LED module  1 . The reflecting layer  4131  is inclined, and extends upwardly and outwardly along the side surface  413 . Preferably, an angle between the reflecting layer  4131  and the bottom surface  411  is in a range from about 30 to 45 degrees. 
     The rough portion  43  and the two retaining portions  45  are protruded downwardly from the bottom surface  411 . The rough portion  43  includes a plurality of continuous protruding portions  431 . The protruding portions  431  are evenly arrayed on the bottom surface  411  and located around the cavity  417 . Each protruding portion  431  has the same shape and size. Each protruding portion  431  is inverted trapeziform, and a width of the protruding portion  431  decreases from a top end connecting the bottom surface  411  to a bottom end away from the bottom surface  411 . An inner surface of each protruding portion  431  may be covered by a reflecting film (not shown) to reflect light back to the interior of the lens  40 . Edges of top ends of adjacent protruding portions  431  connect with each other, and the another parts of the adjacent protruding portions  431  are spaced from each other. The outer edges of the two protruding portions  431  located at outmost sides of the bottom surface  411  connect inner edges of the two retaining portions  45  respectively. 
     The lens  40  are fixed on the first electrode  12  and the second electrode  13  of the LED  10  by the retaining portions  45 . Each retaining portion  45  is also inverted trapeziform. A width of the retaining portion  45  is decreased from a top end connecting the bottom surface  411  to a bottom end away from the bottom surface  411 . A height of the retaining portion  45  is larger than that of the protruding portions  413 . 
     Referring to  FIG. 2 , when the lens  40  is fixed with the LED  10 , the retaining portions  45  are mounted on the first electrode  12  and the second electrode  13  respectively. The rough portion  43  is located above and spaced from the two electrodes  12 ,  13 . A gap  50  is defined between the rough portion  43  and the two electrodes  12 ,  13  to receive cool air therein to cool the LED chip  14 . The encapsulant  15  is received in the cavity  417 , and the side surface of the encapsulant  15  intimately contacts the annular surface  4173 . The top end of the encapsulant  15  is spaced from the second curved surface  4171 . An air chamber  4175  is defined between the top end of the encapsulant  15  and the second curved surface  4171 . Meanwhile, the LED chip  14  is under the second curved surface  4171 . A distance between the LED chip  14  and the second curved surface  4171  is larger than the focal length of the second curved surface  4171 . In this state, light emitted from the LED chip  14  may evenly radiates out of the lens  40 . 
     Referring to  FIG. 3 , during operation of the LED module  1 , a part of light emitted from the LED chip  14  travels to the first curved surface  4151  from the second curved surface  4171  or the annular surface  4173  of the cavity  417 , and another part of the light travels to the side surface  413 . A part of the light arrived at the first curved surface  4151  directly travels out of the lens  40 , and another part of the light arrived at the first curved surface  4151  is reflected back to the light-guiding portion  41 , the retaining portions  45  or the rough portion  43 . Most part of the light arrived at the side surface  413  is directly or indirectly reflected by the reflecting layer  4131  to travel out of the lens  40  through the first curved surface  4151 , and another part is reflected to the retaining portions  45  or the rough portion  43 . The light radiated to the retaining portions  45  or the rough portion  43  is reflected or refracted by the retaining portions  45  or the rough portion  43  to travel out of the lens  40  through the first curved surface  4151 . 
     In the conventional LED module, some light may be leaked from the side surface or the bottom surface. However, in the present disclosure, such part of light can be reflected or refracted back to interior of the lens  40  by reflecting layer  4131 , retaining portions  45  or rough portion  43 . This increases the utilization rate of the light emitted from the LED module  1 . 
     It is to be understood that the above-described embodiments are intended to illustrate rather than limit the disclosure. Variations may be made to the embodiments without departing from the spirit of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.