Patent Publication Number: US-9416943-B2

Title: Light-emitting device and backlight module having the light-emitting device therein

Description:
FIELD 
     The subject matter herein generally relates to a light-emitting device and a backlighting having the light emitting device therein. 
     BACKGROUND 
     Large scale displays are constructed with direct-type backlight module. The direct-type backlight modules are built with light emitting diodes (LEDs) and their lens. The luminance is distributed from the center outwards and the light escaping outwards should be even in quality.  FIG. 1  illustrates a luminance simulation diagram of a current LED of a prior art. The luminance is unequally distributed from the center toward the surrounding that results in uneven lights existing from the direct-type backlight module and bad display quality. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Implementations of the present technology will now be described, by way of example only, with reference to the attached figures. 
         FIG. 1  illustrates a luminance simulation diagram of a current LED of a prior art. 
         FIG. 2  is an isometric view of a light-emitting device of an embodiment of the disclosure. 
         FIG. 3  is an exploded, isometric view of the light-emitting device illustrated in  FIG. 2 . 
         FIG. 4  is a cross-sectional view of the light-emitting device along line IV-IV in  FIG. 2 . 
         FIG. 5  illustrates a luminance simulation diagram of the light-emitting device illustrated in  FIG. 2 . 
         FIG. 6  is a cross-sectional view according to a second embodiment of a backlight module having the light-emitting device of the first embodiment and a diffusion plate therein. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the present disclosure. 
     Several definitions that apply throughout this disclosure will now be presented. 
     The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “substantially” is defined to be essentially conforming to the particular dimension, shape, or other feature that the term modifies, such that the component need not be exact. For example, “substantially cylindrical” means that the object resembles a cylinder, but can have one or more deviations from a true cylinder. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series and the like. 
     The present disclosure is described in relation to a light-emitting device and a backlight module comprising the light-emitting devices. 
       FIGS. 2-4  illustrate a light-emitting device  100 .  FIG. 2  is an isometric view of the light-emitting device  100 .  FIG. 3  is an exploded, isometric view of the light-emitting device  100  illustrated in  FIG. 2 .  FIG. 4  is a cross-sectional view of the light-emitting device  100 , along line IV-IV in  FIG. 2 . 
     As illustrated in  FIG. 2 , the light-emitting device  100  comprises a base  1 , a light source  10  and a diverging unit  20 . The light source  10  and the diverging unit  20  are placed on the base  1 . The base  1  may be a substrate, a circuit board, or any other element prepared for mounting the light source  10  and the diverging unit  20 . Light from the light source  10  is scattered by the diverging unit  20  to contribute to a uniform and even luminance. In the present embodiment, the light source  10  is an LED. 
     The diverging unit  20  includes a divergent lens  22 , a conjugation part  24 , and a diverging ring  26 . The diverging ring  26  is assembled on the divergent lens  22  via the conjugation part  24 . 
     As illustrated in  FIG. 2  and further in  FIGS. 3-4 , the divergent lens  22  includes a light incident surface  222 , a light exiting surface  224 , and a side surface  226 . The light incident surface  222  is abutting the base  1 . The side surface  226  is coupled to the light incident surface  222  and the light exiting surface  224 . The light exiting surface  224  is located furthest from the base  1 . The light exiting surface  224  is an aspherical surface and has a smooth indentation on the top portion of the light exiting surface  224 . The divergent lens  22  defines a receiving space  220  extending into the divergent lens  22  from the light incident surface  222  toward the light exiting surface  224 . The divergent lens  22  has a central axis O. The light source  10  is placed on the base  1  and is received in the receiving space  220  in-line with the axis O. The divergent ring  22  further defines a ring-shaped recess  228  extending into the divergent lens  22  from the light exiting surface  224  toward the light incident surface  222 . The ring-shaped recess  228  is symmetrical about the axis O. 
     The conjugation part  24  is circle and is configured to be inserted into the ring-shaped recess  228 . The conjugation part  24  is partly exposed and projects from the ring-shaped recess  228  when inserted therein. The exposed outer portion of the conjugation part  24  has a plurality of mortises  249 , which are located away from the divergent lens  22 . The conjugation part  24  and the divergent lens  22  may be formed of the same material. In the present embodiment, the conjugation part  24  and the divergent lens  22  are made of polymethylmethacrylate (PMMA). The conjugation part  24  and the diverging ring  22  may be a single unit. 
     A cross section of the diverging ring  26  is round and the ring itself is a torus or donut-shape. The diverging ring  26  has an outer diameter which is less than an inner diameter of the conjugation part  24 . The diverging ring  26  has a plurality of tenons  269  around an outer portion of the diverging ring  26 . The tenons  269  are placed to correspond to the mortises  249  of the conjugation part  24 . The diverging ring  26  is assembled to the conjugation part  24  by inserting the tenons  269  into the mortise  249 . In that way, the diverging ring  26  is arranged on the light exiting surface  224  and in-line with the light source  10 . Since the ring-shaped recess  228  is symmetrical about the axis O, the diverging ring  26  is symmetrical about the axis O. The outer surface of the diverging ring  26  is capable of reflecting light. In the present embodiment, the diverging ring  26  is placed a distance away from the light exiting surface  224 . The distance between the diverging ring  26  and the light exiting surface  224  may be modified depending on the refractive index of light through the divergent lens  22 . In the present embodiment, the diverging ring  26  is made of a PMMA base ring and a reflective coating is formed over the PMMA base ring. Another structure or material can be used to make the outer surface of the diverging ring  26  reflective. 
     When the light-emitting device  100  is working, light from the light source  10  enters the divergent lens  22  from the light incident surface  222  and leaves the divergent lens  22  from the light exiting surface  224 . The diverging ring  26  reflects light from the light source transmitted through the divergent lens  22  in multiple directions. So that the light-emitting device  100  provides light with uniform and even luminance.  FIG. 5  illustrates a luminance simulation diagram of the light-emitting device  100  of the present embodiment. Comparing  FIG. 1 , which illustrates a luminance simulation diagram of a prior-art LED, the luminance provided by the light-emitting device  100  of the present embodiment is more evenly and uniformly distributed. 
       FIG. 6  illustrates a second embodiment, illustrating a backlight module  200  having the light-emitting device  100  of the first embodiment and a diffusion plate  50  therein. The structure of the light-emitting device  100  is not here repeated. 
     The diffusion plate  50  includes an incident surface  52  on one side of the diffusion plate  50  and an exiting surface  54  located on the other side. The exiting surface  54  is on a side of the divergent lens  22  and located furthest from the light-emitting device  100 . The incident surface  52  is parallel to the exiting surface  54 . In other words, the incident surface  52  of the diffusion plate  50  is located on the side which is closest to the light exiting surface  224  of the light-emitting device  100  and faces the light exiting surface  224 . Light coming from the light-emitting device  100  enters the diffusion plate  50  and is further scattered by the diffusion plate  50 . 
     The embodiments shown and described above are only examples. Many details are often found in the art such as the other features of a light-emitting device. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, especially in matters of shape, size, and arrangement of the parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims.