Patent Publication Number: US-8967835-B2

Title: Lens having positioning structure for accurately mounting the lens over a light source module

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure generally relates to optical elements, and particularly to a lens which has a positioning structure capable of accurately mounting the lens over a light source module, for example, an LED package. 
     2. Description of the Related Art 
     LEDs (light emitting diodes) are solid state light emitting source, which are more stable and reliable than other conventional light sources such as incandescent bulbs. Thus, LEDs are being widely used in various fields such as numeral/character displaying elements, signal lights, light sources for lighting and display devices. 
     A conventional light source module includes a printed circuit board, an LED mounted on the printed circuit board by SMT (surface mounted technology), and a lens covering the LED and mounted on the circuit board. Positioning pins of the lens are adhered on patterned zones of the printed circuit board via glue. Since there are position errors when the LED and the lens are mounted on the circuited board, the lens cannot precisely cover the LED at the required position, whereby the lens cannot precisely refract the light from the LED in a manner as required. Accordingly, the light distribution obtained by the conventional LED and lens assembly sometimes cannot satisfy the predetermined requirement. 
     Therefore, it is desirable to provide a light source module having a lens which can overcome the above-described problems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the disclosure can be better understood with reference to the drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present light source module. Moreover, in the drawings, all the views are schematic, and like reference numerals designate corresponding parts throughout the views. 
         FIG. 1  is an isometric view of a lens of a light source module in accordance with one embodiment of the present disclosure. 
         FIG. 2  is a cross-sectional view of the light source module in accordance with a first embodiment of the present disclosure, as taken along line II-II of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of a light source module in accordance with another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , a light source module  100  in accordance with a first embodiment is shown. The light source module  100  includes a substrate  10 , an LED package  20  mounted on the substrate  10 , and a lens  30  disposed on the substrate  10  and covering the LED package  20  whereby light generated by the LED package  20  can be refracted by the lens  30  to obtain a desired light distribution. 
     A cross section of the substrate  10  is rectangular. The substrate  10  includes a top surface  11  and a bottom surface  12  opposite to the top surface  11 . The top surface  11  is flat with circuits (not shown) arranged thereon. In this embodiment, the substrate  10  is a printed circuit board. 
     The LED package  20  is formed on the top surface  11  of the substrate  10 . The LED package  20  electrically connects with circuits of the substrate  10 . The LED package  20  includes a lighting outputting surface  21 . Lights generated from the LED package  20  emits outward via the light outputting surface  21 . Alternatively, a chip received in the LED package  20  can be a chip assembly having a plurality of chips capable of emitting light with different wavelengths. 
     The lens  30  includes a light guiding portion  31 , a supporting portion  32  supporting the light guiding portion  31 , and a latching portion  33  extending downwardly from the light guiding portion  31 . 
     Specifically, the light guiding portion  31  includes a top surface  34 , a bottom surface  35  opposite to the top surface  34 , and a side surface  36  interconnecting the top surface  34  and the bottom surface  35 . 
     The top surface  34  includes a recessed section  341  at a center thereof and an arc section  342  at an outer periphery of the recessed section  341 . The recessed section  341  is concave and depressed toward the LED package  20 . The arc section  342  is convex and oriented towards a direction away from the LED package  20 . A curvature radius of the arc section  342  is greater than that of the recessed section  341 . The side surface  36  is vertical, and interconnects an outer periphery of the arc section  342  and an outer periphery of the bottom surface  35 . 
     In this embodiment, the bottom surface  35  is annular. An optical concave  37  is depressed from a center of the bottom surface  35  toward the top surface  34 . The optical concave  37  is aligned with the recessed section  341 . The optical concave  37  is above the LED package  20  and corresponds to the LED package  20 . In this embodiment, the optical concave  37  is domical. A bore diameter of the optical concave  37  gradually decreases from the bottom surface  35  to the top surface  34  along an optical axis of the lens  30 . 
     The supporting portion  32  is located at a periphery of the bottom surface  35 . In this embodiment, the supporting portion  32  is designated as three supporting posts evenly spaced from each other. Alternatively, the supporting portion  32  can be annular, or have a shape of a long strip. 
     The latching portion  33  extends downwardly from the bottom surface  35 . The latching portion  33  is integrally formed on the bottom surface  35  of the lens  30  and located around the optical concave  37 . The latching portion  33  is surrounded by the supporting portion  32 . A real estate occupied by the latching portion  33  is smaller than that occupied by the bottom surface  35 . In this embodiment, the latching portion  33  is a rectangular ring protruding downwardly from the bottom surface  35 . The latching portion  33  includes four long strips  331  connecting each other to form the rectangular ring. A rectangular engaging hole  38  is defined and surrounded by the latching portion  33 . Each length and width of the engaging hole  38  of the latching portion  33  is larger than the bore diameter of the optical concave  37 . In other words, a real estate occupied by the engaging hole  38  is larger than that occupied by the optical concave  37 , while centers of the engaging hole  38  and the optical concave  37  are aligned with each other and both located at the optical axis of the lens  30 . 
     A step is formed by a portion of the bottom surface  35  between the latching portion  33  and the optical concave  37 . A top end of the LED package  20  is fittingly received in the engaging hole  38  with a top surface of the LED package  20  engaging with the step. 
     A height of the latching portion  33  is lower than that of the supporting portion  32 . 
     When the light source module  100  is assembled, the LED package  20  is mounted on the substrate  10  by SMT, and then the lens  30  is attached to the substrate  10 . Specifically, the top end of the LED package  20  is fittingly received in the engaging hole  38 , so that a relative position of the LED package  20  and the optical concave  37  of the lens  30  is accurate. In this embodiment, the light outputting surface  21  is received in the engaging hole  38  and abuts against the bottom surface  35  defining the step. Alternatively, the light outputting surface  21  can also be spaced from the bottom surface  35  with a small gap. That is, the light outputting surface  21  is lower than the bottom surface  35 . The only requirement is that the upper end of the LED package  20  is fittingly received in the engaging hole  38  defined by the latching portion  33 . 
     Since the lens  30  includes a latching portion  33  adjacent to the periphery of the optical concave  37 , an engaging hole  38  is defined by the latching portion  33  for receiving the LED package  20 . Therefore, a relative position between the LED package  20  and the lens  30  is accurate, whereby the top surface  34  of the lens  30  can correctly refract the light from the light outputting surface  21  of the LED package  20  to obtain the required light distribution. 
     Referring to  FIG. 3 , a light source module  100   a  in accordance with a second exemplary embodiment is shown. The light source module  100   a  is similar to the light source module  100  of the first embodiment. The difference is that, the latching portion  33   a  of the lens  30   a  obliquely extends from the bottom surface  35   a  toward the substrate  10   a . In this embodiment, a size of the engaging hole  38   a  defined by an inner surface of the latching portion  33   a  gradually increases from the bottom surface  35   a  to the substrate  10   a . The LED package  20   a  is easier to slide into the engaging hole  38   a  along the inner surface of the latching portion  33   a  to be fittingly engaged with the latching portion  33   a.    
     The engaging holes  38 ,  38   a  respectively defined by latching portions  33 ,  33   a  are not limited to be square. The engaging holes  38 ,  38   a  can also be circular, triangular and so on. 
     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. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.