Abstract:
An exemplary optical plate is used in a backlight module having a frame. The optical plate includes a main body and one bracket extension. The main body has a light input surface, and a light output surface opposite to the light input surface. The bracket extension extends from one end of the main body for fixing the optical plate to the frame. A backlight module using the optical plate is also provided.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to optical plates, and particularly, to an optical plate used in a backlight module of a liquid crystal display device. 
         [0003]    2. Discussion of the Related Art 
         [0004]    In a liquid crystal display device (LCD device), liquid crystal is a substance that does not itself illuminate light. Instead, the liquid crystal relies on light received from a light source to display information. In the case of a typical liquid crystal display device, a backlight module powered by electricity supplies the needed light. 
         [0005]      FIG. 8  depicts a backlight module  100 . The backlight module  100  includes a frame  11 , a reflective plate  12 , a plurality of lamps  13 , a light diffusion plate  14 , a prism sheet  15 , and an upper light diffusion film  16 . The frame  11  includes a bottom frame  112 , and an upper frame  116 . The bottom frame  112  defines a receiving chamber  114 . The lamps  13  are aligned above the reflective plate  12  in the receiving chamber  114 . The reflective plate  12  is positioned on a base of the bottom frame  112 . The light diffusion plate  14 , the prism sheet  15 , and the upper light diffusion film  16  are positioned on the bottom frame  112  over the receiving chamber  114  in that order. The upper frame  116  serves as a binder for fixing or holding the light diffusion plate  14 , the prism sheet  15 , and the upper light diffusion film  16  tightly to the bottom frame  112 . 
         [0006]    In assembling, firstly, the reflective plate  12  is positioned on the base of the bottom frame  112 . Secondly, the lamps  13  are regularly disposed in the receiving chamber  114  of the bottom frame  112 . Thirdly, optical elements, such as the light diffusion plate  14 , the prism sheet  15  and the upper light diffusion film  16 , are respectively positioned on the bottom frame  112  over the receiving chamber  114 , in that order. Finally, the upper frame  116  is positioned on the upper light diffusion film  16  and fixed to the bottom frame  112 . However, the process of fixing the optical elements respectively on the bottom frame  112  requires high precision and costs time. In addition, this process may easily damage or scratch the optical elements. Thus, the backlight module  100  is unduly complicated in assembling and therefore costly to manufacture. 
         [0007]    What is needed, therefore, is a new optical plate and a backlight module using the optical plate that can overcome the above-mentioned shortcomings. 
       SUMMARY 
       [0008]    In one aspect, an optical plate is used in a backlight module having a frame. The optical plate includes a main body and one bracket extension. The main body has a light input surface, and a light output surface opposite to the light input surface. The bracket extension extends from one end of the main body for fixing the optical plate to the frame. 
         [0009]    In another aspect, a backlight module includes a frame, a plurality of lamps in the frame, and an optical plate. The optical plate includes a main body, and one bracket extension. The main body has a light input surface, and a light output surface opposite to the light input surface. The light input surface is adjacent to the lamps. The bracket extension extends from one end of the main body for fixing the optical plate to the frame thereat. 
         [0010]    Other advantages and novel features will become more apparent from the following detailed description of various embodiments, when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present optical plate and backlight module. Moreover, in the drawings, like reference numerals designate corresponding parts throughout several views, and all the views are schematic. 
           [0012]      FIG. 1  is a side, cross-sectional view of a backlight module according to a first preferred embodiment of the present invention. 
           [0013]      FIG. 2  is a top plan view of an optical film of the backlight module of  FIG. 1 . 
           [0014]      FIG. 3  is an isometric view of an optical plate of the backlight module of  FIG. 1 . 
           [0015]      FIG. 4  is a side, partial, cross-sectional view of a backlight module according to a second preferred embodiment of the present invention. 
           [0016]      FIG. 5  is a side, partial, cross-sectional view of a backlight module according to a third preferred embodiment of the present invention. 
           [0017]      FIG. 6  is a side, partial, cross-sectional view of a backlight module according to a fourth preferred embodiment of the present invention. 
           [0018]      FIG. 7  is a side, partial, cross-sectional view of a backlight module according to a fifth preferred embodiment of the present invention. 
           [0019]      FIG. 8  is a side, cross-sectional view of a conventional backlight module. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Reference will now be made to the drawings to describe preferred embodiments of the present optical plate and backlight module using the optical plate, in detail. 
         [0021]    Referring to  FIG. 1  a backlight module  200  in accordance with a first preferred embodiment of the present invention is shown. The backlight module  200  includes a frame  21 , a plurality of lamps  23 , a light diffusion plate  24 , an optical plate  25 , and an optical film  26 . 
         [0022]    The frame  21  includes a base  211 , a plurality of sidewalls  213 , and two supporting portions  215 . The sidewalls  213  extend from a periphery of the base  211 . The supporting portions  215  extend from edges of the sidewalls  213  on opposite sides of the base  211  correspondingly. The base  211  and the sidewalls  213  cooperatively define a receiving chamber  217 . The frame  21  is made of metal or plastic materials with a high reflectivity rate. Preferably, a high reflectivity coating is deposited on the interior of the frame  21  for improving the light reflectivity rate of the frame  21 . The lamps  23  are disposed in the receiving chamber  217  in a regular manner. The light diffusion plate  24 , the optical plate  25 , and the optical film  26  are respectively positioned on the supporting portion  215  over the receiving chamber  217 . 
         [0023]    The lamps  23  can be point light sources such as light emitting diodes, or linear light sources such as cold cathode fluorescent lamps. 
         [0024]    The light diffusion plate  24  is used to diffuse light. The light diffusion plate  24  is made of transparent resin with a plurality of light diffusion particles uniformly dispersed in the transparent resin. 
         [0025]    The optical film  26  can be a light diffusion sheet or a light polarizing sheet. Referring to  FIG. 2 , in the preferred embodiment, the optical film  26  includes four tab portions  261  with each side having two tab portions  261 . Each tab portion  261  defines a through hole  263  therein. 
         [0026]    Referring to  FIGS. 1 and 3  again, the optical plate  25  includes a main body  252 , and two bracket extensions  254 . The bracket extensions  254  extend from edges of the main body  252  on opposite sides of the optical plate  25  correspondingly. The main body  252  has a light input surface  2521 , and a light output surface  2523 . The light input surface  2521  faces the light diffusion plate  24 . The light output surface  2523  faces the optical film  26 . In addition, the main body  252  has a plurality of tapered depressions  2522  defined on the light input surface  2521 , and a plurality of elongated cylindrical protrusions  2524  formed on the light output surface  2523 . 
         [0027]    Each of the bracket extensions  254  includes a base  2541 , an inner sidewall  2543 , an outer sidewall  2545 , and two fixing columns  2547 . Each inner sidewall  2543  connects with the main body  252 . Each inner sidewall  2543  defines two cutouts  2544  for engaging with the two tab portions  261  on a corresponding side of the optical film  26 . The inner sidewalls  2543  of the bracket extensions  254  and the light input surface  2521  cooperatively define a first receiving chamber  2531 . The inner sidewalls  2543  of the bracket extensions  254  and the light output surface  2523  cooperatively define a second receiving chamber  2533 . In each bracket extensions  254 , the base  2541  connects the inner sidewall  2543  and the outer sidewall  2545 . The base  2541 , the inner sidewall  2543 , and outer sidewall  2545  of each bracket extensions  254  cooperatively define a cavity  2549 . The fixing columns  2547  are located on the base  2541  in the cavity  2549  adjacent to the cutouts  2544  correspondingly. In addition, each fixing column  2547  has a pin  2548  at a top of the fixing column  2547  for positioning the optical film  26 . 
         [0028]    The light diffusion plate  24  is located in the first receiving chamber  2531 . The light diffusion plate  24  can be fixed to the optical plate  25  by fusion, such as heat fusion or ultrasonic fusion. In alternative embodiments, the light diffusion plate  24  can be fixed to the optical plate  25  by conglutinating or other fastening means. A main portion of the optical film  26  is located in the second receiving chamber  2533 . The tab portions  261  of the optical film  26  extend through the corresponding cutouts  2544 . The pins  2548 , of the fixing columns  2547  of the optical plate  25 , engage in the corresponding through holes  263  defined in the tab portions  261  of the optical film  26 . The bases  2541  of the bracket extensions  254  of the optical plate  25  are fixed to the corresponding supporting portions  215  by an adhesive (not shown). 
         [0029]    In assembling, the light diffusion plate  24  and the optical film  26  are pre-assembled with the optical plate  25 , and then this assemblage is fixed to the frame  21 . Therefore, an upper frame of the conventional backlight module can be omitted. Thus a process for assembling the backlight module  200  is improved, and cost of the backlight module  200  is decreased. In addition, because the light diffusion plate  24  and the optical film  26  are fixed to the optical plate  25  in advance, the light diffusion plate  24  and the optical film  26  are not easily damaged or scratched. 
         [0030]    Referring to  FIG. 4 , a backlight module  300  in accordance with a second preferred embodiment of the present invention is shown. The backlight module  300  is similar in principle to the backlight module  200  of the first embodiment. The backlight module  300  includes a frame  31 , a plurality of lamps  33 , a light diffusion plate  34 , an optical plate  35 , an optical film  36 , and a fixing sheet  37 . However, the optical plate  35  has a main body  352  and a single bracket extension  354 . The main body  352  has a light input surface  3521 , and a light output surface  3523 . The main body  352  includes a plurality of tapered protrusions  3522  formed on the light input surface  3521 , and a plurality of spherical depressions  3524  defined in the light output surface  3523 . An outer sidewall  3545  of the bracket extension  354  has a positioning pin  3546 . A tab portion  361  of the optical film  36  defines a through hole  363  therein. The bracket extension  354  has a column  3547  with a stepped pin  3548  on a top of the column  3547 . A diameter of through hole  363  is larger than a maximum diameter of the stepped pin  3548 . The fixing sheet  37  defines two positioning holes  371 ,  373  therein. In assembling, the stepped pin  3548  runs through the through hole  363  of the optical film  36 , and engages in the positioning hole  373  of the fixing sheet  37 . Meanwhile, the positioning pin  3546  engages in the positioning hole  371  of the fixing sheet  37 . Because the diameter of through hole  363  is larger than the maximum diameter of the stepped pin  3548 , the optical film  36  can extend along an X-direction (see X-Y coordinates in  FIG. 4 ). Therefore, the optical film  36  is not deformed. 
         [0031]    Referring to  FIG. 5 , a backlight module  400  in accordance with a third preferred embodiment of the present invention is shown. The backlight module  400  includes a frame  41 , a plurality of lamps  43 , a light diffusion plate  44 , an optical plate  45 , an optical film  46 , and a screw  47 . The backlight module  400  is similar in principle to the backlight module  200  of the first embodiment. However, a column  4547  of the bracket extension  454  defines a threaded hole  4548  in an upper surface thereof. A tab portion  461  of the optical film  46  defines a through hole  463  therein. In assembling, the column  4547  is inserted through the through hole  463  of the optical film  46 , and then the screw  47  is screwed into the threaded hole  4548 , thereby the optical film  46  fixed to the optical plate  45 . 
         [0032]    Referring to  FIG. 6 , a backlight module  500  in accordance with a fourth preferred embodiment of the present invention is shown. The backlight module  500  is similar in principle to the backlight module  400  of the third embodiment. The backlight module  500  includes a frame  51 , a plurality of lamps  53 , a light diffusion plate  54 , an optical plate  55 , and an optical film  56 . However, a bracket extension  554  of the optical plate  55  is solid. The bracket extension  554  includes a top surface  5540 , a side surface  5542 , and a protecting protrusion  5544 . The side surface  5542  connects with the top surface  5540 . When the backlight module  500  is used in a liquid crystal display device, the top surface  5540  may support a liquid crystal display panel  58  of the liquid crystal display device, and the protecting protrusion  5544  may protect a drive circuit  582  connected to the liquid crystal display panel  58 . 
         [0033]    Referring to  FIG. 7 , a backlight module  600  in accordance with a fifth preferred embodiment of the present invention is shown. The backlight module  500  is similar in principle to the backlight module  400  of the third embodiment. The backlight module  600  includes a frame  61 , a plurality of lamps  63 , a light diffusion plate  64 , an optical plate  65 , and an optical film  66 . However, the light diffusion plate  64  includes a plurality of V-shaped protrusions  642  on a light input surface  641  of the light diffusion plate  64 . A base  6541  of a bracket extension  654  of the optical plate  65  has a positioning pin  6542 . A supporting portion  615  of the frame  61  defines a positioning through hole  6152  therethrough. In assembling, the positioning pin  6542  engages in the positioning through hole  6152 , thereby the optical plate  65  is fixed to the frame  61 . In alternative embodiments, the optical plate  65  is fixed to the frame  61  by an adhesive, a screw, or a fastener. 
         [0034]    It is noted that the scope of the present optical plate and backlight module is not limited to the embodiments described above. For example, in the backlight module  200 , the light diffusion plate  24 , the optical plate  25  and the optical film  26  can be integrally formed. The tapered depressions  2522  or elongated cylindrical protrusions  2524  can be replaced by elongated cylindrical depressions, elongated V-shaped depressions, or elongated V-shaped protrusions. 
         [0035]    Finally, while various embodiments have been described and illustrated, the invention is not to be construed as being limited thereto. Various modifications can be made to the embodiments by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.