Abstract:
A device for fastening the lighting units in a backlight module is provided. A rigid board partially laps over the adjacent lighting unit or units. The rigid board and the backboard have holes respectively such that a bolt is passed through the holes and locked on a nut. Accordingly the rigid board exerts a compressing strength to fasten the adjacent lighting unit or units onto the backboard.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a fastening device, and more particularly relates to a fastening device utilized in a backlight module to fasten the lighting units.  
         [0003]     2. Description of the Prior Art  
         [0004]     Referring to  FIG. 1 , in the prior art, there is a fastening device used to fasten the lighting units  12  of the backlight module  1  within a liquid crystal display. The backlight module  1  composes a backboard  11  and a plurality of lighting units  12  arranged in equal space and in parallel on the backboard  11 . Each of the lighting units  12  includes a plurality of lighting elements  121  and an aluminum board  122  carrying the lighting elements  121 , wherein the lighting elements  121  are soldered above the aluminum board  122  and connected with the conductive trace (not shown). And, the heat generated by operating the lighting units  12  is dissipated to the backboard  11  through the aluminum board  122 .  
         [0005]     Still referring to  FIG. 1 , the conventional method of the prior art used to fasten the lighting unit  12  is to form the corresponding holes between the aluminum board  122  and the backboard  11 , and then use bolts  141  to pass through the holes of the aluminum board  122  and the backboard  11 . Thereafter, the bolts  141  are locked together with the nuts placed at the other side of the backboard  11  and the lighting units  12  are thus fastened to the backboard  11 .  
         [0006]     Since the material of the aluminum board  122  is not hard enough such that it is inevitable to have some voids between the aluminum board  122  and the backboard  11  to block the thermal dissipation. Therefore, in order to let the aluminum board  122  and the backboard  11  have the effect of sticking tightly, in the prior art, the solution is using lots of bolts  141  and nuts. However, it increases the complexity of the backlight module, the time of the assembling, and the cost of the producing during the fabricating.  
       SUMMARY OF THE INVENTION  
       [0007]     According to the drawbacks described above, the conventional method of fastening the lighting units in the backlight module suffers complexity in assembling and high cost of manufacturing, and therefore, the purpose of the present invention is to provide a fastening device utilized in a backlight module to fasten the lighting units. An object of the present invention is to firmly fasten the lighting units unto the backboard of the backlight module so that the assembling is simplified and the required amount of the nuts and bolts is greatly reduced.  
         [0008]     According to the object described above, the present invention discloses a fastening device utilized in a backlight module to fasten the lighting units and the resultant backlight module. A rigid board partially laps over the adjacent lighting unit or units. The rigid board and the backboard have holes respectively such that bolts are passed through the holes and locked on nuts. Accordingly the rigid board exerts a compressing strength to fasten the adjacent lighting unit or units onto the backboard. In addition to the simplification of the assembling and the decrease of the amount of the nuts and bolts required, the efficiency of thermal dissipation between the lighting units and the backboard is further improved. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The accompany drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings:  
         [0010]      FIG. 1  is a perspective view illustrating the backlight module by using bolts and nuts to fasten the lighting units in the prior art;  
         [0011]      FIGS. 2A-2B  are perspective views illustrating the lighting units within the backlight module fastened by the rigid metal board according to one embodiment of the present invention;  
         [0012]      FIG. 2C  is a perspective view illustrating a thermal conductive pad inserted between the metal board and the backboard according to another embodiment of the present invention;  
         [0013]      FIG. 2D  is a perspective view illustrating a heat sink utilized in the backlight module according to a further embodiment of the present invention;  
         [0014]      FIG. 2E  is a perspective view illustrating a reflective board configured on the lighting unit and the rigid metal board according to a further embodiment of the present invention; and  
         [0015]      FIGS. 3A  to  3 E illustrate other embodiments of the present invention, which are similar to those of  FIGS. 2A-2E  except for a modified rigid metal board. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]     The following is the detailed description of the present invention, which describes the backlight module and the lighting units, but the detailed structure composition and the operating theory are not discussed. The portions relating to the conventional techniques are briefly described, and the parts of the drawings are not proportionally drafted. While embodiments are discussed, it is not intended to limit the scope of the present invention. Except expressly restricting the amount of the components, it is appreciated that the quantity of the disclosed components may be greater than that disclosed.  
         [0017]     One of the preferred embodiments of the present invention discloses a backlight module in which the lighting units are fastened. First referring to  FIG. 2A , a backlight module  2  is composed of a backboard  21  and a plurality of lighting units  22  arranged in equal space and in parallel to one another on the backboard  21 . Each lighting unit  22  comprises a plurality of lighting elements  221  and a metal board  222  carrying the lighting elements  221 . The lighting element  221  can be a conventional lighting device such as a light emitting diode (LED) soldered on the metal board  222 . On the metal board  222  is the conductive trace (not shown). The boards  222  in general can be metal boards, such as aluminum boards, or printed circuit boards (PCBs) having good thermal conductivity. Therefore, the heat generated from the lighting element  221  could be effectively dissipated to the backboard  21  through the metal boards/PCBs  222 .  
         [0018]     Still referring to  FIG. 2A , in the embodiment of the present invention, the lighting units  22  are fastened by using a rigid metal board  23  and fasteners ( 241 ,  242 ), where holes  211  and  231  are correspondingly formed in the backboard  21  and the rigid metal board  23 , respectively. The rigid metal board  23  can be a tinned steel board or a stainless steel board, and has a raised portion along its center to face towards the backboard  21 . The opposite of the raised portion is a concave side  232  facing upwards, which is in a direction parallel with the metal board  222 . Beside, the fasteners mentioned above can be bolts  241  and nuts  242 .  
         [0019]     Now referring to  FIG. 2B , when the rigid metal board  23  is moved and configured between two adjacent metal boards  222 , the two sides of the rigid metal board  23  with good rigidity lap over the adjacent portions of the metal boards  222 . And, when the bolts  241  are passed through the holes  231  of the concave portion  232  and the holes  211  of the backboard  21 , and locked together with nuts  242  (not shown in the figure), the rigid metal board  23  can be fastened on the backboard  21 . And, the strength of the compressing provided by the rigid metal board  23  can fasten the adjacent boards  222  on the backboard  21 . In this embodiment, the bolts  241  are passed through the holes  211  and  231  and locked in the nuts  242 . But based on other embodiments of the present invention, however, the holes  211  of the backboard  21  can be replaced by threaded holes, and the bolts replaced by screws. At the time, the screws are passed through the threaded holes and locked directly to the backboard  21 . Accordingly, the lighting units  22  are thus fastened in the backlight module  2  and the heat generated during operating the lighting elements  221  can be dissipated from the metal board  222  to the rigid metal board  23 , and ultimately to the backboard  21 , thereby enhancing the efficiency of the thermal dissipation and also reducing the needed amount of bolts/screws and nuts.  
         [0020]     In order to further reduce the voids between the metal board  222  and the backboard  21 , based on other embodiments of the present invention as referring to  FIG. 2C , it is configured a thermally conductive pad  25  between the metal board  222  and the backboard  21  to increase the contact area to enhance the efficiency of the thermal dissipation. And the thermal pad  25  can improve the tolerance between the metal board  222  and the backboard  21  during producing the materials.  
         [0021]     Instead of using the thermal pad  25 , the efficiency of thermal dissipation of the backlight module  2  according to the embodiment of the present invention can also be improved by adding a heat sink  26  or replacing the backboard  21  by the heat sink  26  as shown in  FIG. 2D .  
         [0022]     According to another embodiment of the present invention, as shown in  FIG. 2E , in which side-emitting lighting elements  223  are used as the light source, a reflective board  27  is required within the lighting unit. The reflective board  27  has holes  271  with dimension larger than that of the side-emitting lighting elements  223 , such that the side-emitting lighting elements  223  could protrude from the holes  271 . The reflective board  27  covers the metal boards  222 , which are fastened by the rigid metal board  23 , and accordingly, the side-emitting lighting elements  223  generate uniform light out of the backlight module.  
         [0023]      FIGS. 3A  to  3 E illustrate other embodiments of the present invention, and will be described with respect to the embodiments of  FIGS. 2A  to  2 E, respectively. The composing elements in  FIGS. 3A  to  3 E that are the same as corresponding ones in  FIGS. 2A  to  2 E are labeled with the same reference numerals, and will be only briefly discussed or even passed over. The elements that are modified, however, are labeled with different reference numerals, and will be discussed as follows.  
         [0024]      FIGS. 3A-3B  illustrate a backlight module  2  similar to that of  FIGS. 2A-2B  except that the rigid metal board  33  mainly includes two portions arranged in a step configuration. Specifically, the first portion  332  is recognized as the bottom step, and the second portion  333  as the top step. In assembling, when the bolts  241  are passed through the holes  231  of the bottom portion  332  and the holes  211  of the backboard  21 , and locked together with nuts  242 , the rigid metal board  33  can be fastened on the backboard  21 . And, the strength of the compressing provided by the rigid metal board  33 , especially the top portion  333 , can fasten the adjacent boards  222  on the backboard  21 .  
         [0025]      FIG. 3C  illustrates a backlight module similar to that of  FIG. 2C  except that the rigid metal board  33  mainly includes two portions arranged in a step configuration as described in the previous paragraph. Referring to  FIG. 3C , a thermally conductive pad  25  is configured between the metal board  222  and the backboard  21  to increase the contact area to enhance the efficiency of the thermal dissipation.  
         [0026]      FIG. 3D  illustrates a backlight module similar to that of  FIG. 2D  except that the rigid metal board  33  mainly includes two portions arranged in a step configuration as described in the previous paragraphs. The efficiency of thermal dissipation of the backlight module according to this embodiment can be improved by adding a heat sink  26  or replacing the backboard  21  by the heat sink  26 .  
         [0027]      FIG. 3E  illustrates a backlight module similar to that of  FIG. 2E  except that the rigid metal board  33  mainly includes two portions arranged in a step configuration as described in the previous paragraphs. In this embodiment, the reflective board  27  covers the metal boards  222 , which are fastened by the rigid metal board  33 , and accordingly, the side-emitting lighting elements  223  generate uniform light out of the backlight module.  
         [0028]     The foregoing description is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. In this regard, the embodiment or embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly and legally entitled.