Abstract:
An exemplary backlight module ( 300 ) includes a frame ( 350 ) and a bottom plate ( 370 ). One of the frame and the bottom plate includes a plurality of elastically deformable buckling structures ( 358 ), and the other of the frame and the bottom plate includes a plurality of protrusions ( 204, 374 ) corresponding to the buckling structures. When the bottom plate is attached to the frame, the bottom plate and the frame are pressed together along a first axis, and the buckling structures elastically deform and then elastically rebound such that the buckling structures are engaged with the protrusions and the bottom plate is fixed to the frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is related to, and claims the benefit of, a foreign priority application filed in Taiwan as Application No. 95144737 on Dec. 1, 2006. The related application is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to backlight modules and liquid crystal display (LCD) devices using backlight modules, and more particularly to a backlight module that can be assembled conveniently. 
     GENERAL BACKGROUND 
     Liquid crystal display devices are commonly used as display devices for compact electronic apparatuses, because they not only are very thin but also provide good quality images with little power consumption. 
       FIG. 9  shows an exploded, isometric view of a typical LCD device  1 . The LCD device  1  includes a bezel  10 , a liquid crystal panel  20 , and a backlight module  40  disposed adjacent to the liquid crystal panel  20 . 
     The bezel  10  includes a generally rectangular top plate  102 , and four first side walls  104  extending downward from four edges of the top plate  102 . The top plate  102  defines an essentially rectangular display region  107  thereof. Each first side wall  104  defines two first notches  106  therein. 
     The backlight module  40  includes a brightness enhancement film (BEF)  422 , a diffusion film  421 , a light guide plate (LGP)  430 , an illuminator  440 , a reflection film  460 , a frame  450 , and a bottom tray  470 . The frame  450 , the BEF  422 , the diffusion film  460 , the LGP  430 , and the reflection film  460  are arranged in that order from top to bottom. 
     The LGP  430  includes a top light incident surface  433 , a light emitting surface  431  adjoining the light incident surface  433 , and a bottom surface  432  adjoining the light incident surface  433 . The illuminator  440  is positioned opposite the light incident surface  433 . 
     The frame  450  includes four second side walls  452  arranged end to end, and a supporting board  454 . Each second side wall  452  includes two first protrusions  456  and two second protrusions  457  integrally extending perpendicularly outwardly from an outer surface (not labeled) thereof. The supporting board  454  has a frame shape, and integrally extends perpendicularly inward from inner surfaces (not labeled) of the second side walls  452 . The frame  450  therefore defines an upper space for accommodating the liquid crystal panel  20 , and a lower space for accommodating the BEF  422 , the diffusion film  421 , the LGP  430  and the reflection film  460 . The first protrusions  456  correspond in position to the first notches  106 . 
     The bottom tray  470  includes a bottom wall  472  and eight side plates  474 . The side plates  474  extend perpendicularly upward from four sides of the bottom wall  472 . Two side plates  474  are located at each of four corners of the bottom tray  470 , respectively. Each side plate  474  defines a second notch  476 , corresponding to one of the second protrusions  457  of a respective second side wall  452  of the frame  450 . 
     When the LCD device  1  is assembled, the BEF  422 , the diffusion film  421 , the LGP  430 , and the reflection film  460  are received in the lower space. The second protrusions  457  of the second side walls  452  of the frame  450  are engagingly received in the second notches  476  of the bottom tray  470 . Thereby, the frame  450  and the bottom tray  470  are locked together. The liquid crystal panel  20  is received in the upper space. The first protrusions  456  are engagingly received in the first notches  106 , and the frame  450  and the bezel  10  are thereby locked together. 
     When the LCD device  1  is assembled, this is typically performed manually by a human operator. The bottom tray  470  and the frame  450  are generally locked together by force applied in four different directions corresponding to the four second side walls  452 . The bezel  10  and the frame  450  are generally locked together by force applied in four different directions corresponding to the four second side walls  452 . Thus assembly or disassembly of the LCD device  1  is somewhat complicated, problematic, and time-consuming. In addition, a size of each first protrusion  456  is usually slightly less than a size of each corresponding first notch  106 , in order to facilitate assembly. However, this may result in loose engagement of the first protrusions  456  in the first notches  106 . Similarly, a size of each second protrusion  457  is usually slightly less than a size of each corresponding second notch  476 , in order to facilitate assembly. However, this may result in loose engagement of the second protrusions  457  in the second notches  476 . 
     What is needed, therefore, is a backlight module and a liquid crystal display device using the backlight module that can overcome the above-described deficiencies. 
     SUMMARY 
     In one embodiment, a backlight module includes a frame and a bottom plate. One of the frame and the bottom plate includes a plurality of elastically deformable buckling structures, and the other of the frame and the bottom plate includes a plurality of protrusions corresponding to the buckling structures. When the bottom plate is attached to the frame, the bottom plate and the frame are pressed together along a first axis, and the buckling structures elastically deform and then elastically rebound such that the buckling structures are engaged with the protrusions and the bottom plate is fixed to the frame. 
     In another embodiment, a liquid crystal display device includes a liquid crystal panel and a backlight module. The backlight module includes a frame and a bottom plate. One of the frame and the bottom plate includes a plurality of elastically deformable buckling structures, and the other of the frame and the bottom plate includes a plurality of protrusions corresponding to the buckling structures. When the bottom plate is attached to the frame, the bottom plate and the frame are pressed together along a first axis, and the buckling structures elastically deform and then elastically rebound such that the buckling structures are engaged with the protrusions and the bottom plate is fixed to the frame. 
     Other novel features and advantages will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, all the views are schematic. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded, isometric view of an LCD device according to an exemplary embodiment of the present invention, the LCD device including a bezel, a frame and a bottom plate. 
         FIG. 2  is an enlarged view of a circled portion II of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of part of the frame taken along line III-III of  FIG. 1 . 
         FIG. 4  is an enlarged view of a circled portion IV of  FIG. 1 . 
         FIG. 5  is a cross-sectional view of part of the bezel taken along line V-V of  FIG. 1 . 
         FIG. 6  is an enlarged view of a circled portion VI of  FIG. 1 . 
         FIG. 7  is a cross-sectional view of part of the bottom plate taken along line VII-VII of  FIG. 1 . 
         FIG. 8  is similar to  FIG. 3 , but also showing part of the bezel engaged with the frame, and part of the bottom plate engaged with the frame. 
         FIG. 9  is an exploded, isometric view of a conventional LCD device. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Reference will now be made to the drawings to describe preferred and exemplary embodiments in detail. 
     Referring to  FIG. 1 , an exploded, isometric view of an LCD device according to an exemplary embodiment of the present invention is shown. The LCD device  2  includes a bezel  200 , a liquid crystal panel  210 , and a backlight module  300 , arranged in that order from top to bottom. 
     The backlight module  300  includes a BEF  322 , a diffusion film  321 , an LGP  330 , an illuminator (not labeled), a reflector  360 , a frame  350 , and a bottom plate  370 . The BEF  322 , the diffusion film  321 , the LGP  330 , the reflector  360  and the bottom plate  370  are arranged in that order from top to bottom. 
     The LGP  330  includes a top light incident surface  333 , a light emitting surface  331  adjoining the light incident surface  333 , and a bottom surface  332  adjoining the light incident surface  333 . The illuminator is positioned opposite the light incident surface  333 . The reflector  360  is positioned adjacent to the bottom surface  332 . 
     The frame  350  includes four side walls  352  arranged end to end, and a supporting board  354 . The supporting board  354  has a frame shape, and integrally extends perpendicularly inward from inner surfaces (not labeled) of the side walls  352 . The supporting board  354  defines an opening for allowing light rays to pass therethrough. 
     Referring also to  FIG. 2  and  FIG. 3 , each of a pair of two opposite short side walls  352  includes an upside  355  and an underside  356 . The short side walls  352  each define a plurality of first notches  357 . The notches  357  are respectively located at the underside  356  and the upside  355  of each side wall  352 . Each notch  357  at the upside  355  is directly above a corresponding notch  357  at the underside  356 . The short side walls  352  each also include a plurality of buckling structures  358 , which are located in the notches  357  respectively. The buckling structures  358  at the upsides  355  of the side walls  352  are essentially coplanar with the upsides  355 . The buckling structures  358  at the undersides  356  of the side walls  352  are essentially coplanar with the undersides  356 . Each of the buckling structures  358  includes a cap portion  3582  and a body portion  3584 . The body portion  3584  extends vertically from a main body of the short side wall  352  at a bottom of the notch  357 . The cap portion  3582  extends perpendicularly outwardly from a distal end of the body portion  3584 . The body portion  3584  and the cap portion  3582  cooperatively define a hole  3586  therein. The buckling structure  358  therefore has a general shape of a hollow mushroom. The buckling structure  358  is elastically deformable. A height of the buckling structure  358  is generally equal to a depth of the notch  357 . A depth of the hole  3586  is slightly less than the depth of the notch  357 . An outer diameter of the cap portion  3582  is greater than an outer diameter of the body portion  3584 . The buckling structures  358  can be made of plastic. In one embodiment, the buckling structures  358  and the frame  350  are made of the same plastic material. In another embodiment, the buckling structures  358  are made of suitable elastic material that is more elastically deformable than plastic. 
     Referring also to  FIG. 4  and  FIG. 5 , the bezel  200  includes a generally rectangular top plate  202 . The top plate  202  defines an opening (not labeled) that serves as a display region. The top plate  202  includes a plurality of depressed collars  204 , thus defining a plurality of first hollows (not labeled) in the depressed collars  204 . The first hollows are generally disc-shaped. Each of the depressed collars  204  defines a first through hole  206  therein. The first through holes  206  of the depressed collars  204  correspond to the buckling structures  358  located at the upsides  355  of the short side walls  352 . The depressed collars  204  are essentially coplanar with one another. A diameter of each first through hole  206  is less than a diameter of the first hollow. A diameter of the first hollow is substantially equal to the outer diameter of the cap portion  3582  of the corresponding buckling structure  358 . 
     Referring also to  FIG. 6  and  FIG. 7 , the bottom plate  370  includes a generally rectangular main body  372 . The main body  372  is substantially planar. The main body  372  includes a plurality of upraised collars  374 , thus defining a plurality of second hollows in the upraised collars  374 . The second hollows are generally disc-shaped. Each upraised collar  374  has a structure similar to each depressed collar  204 . The upraised collar  374  defines a second through hole  376  therein. The second through holes  376  of the upraised collars  374  correspond to the buckling structures  358  located at the undersides  356  of the short side walls  352 . The upraised collars  374  are essentially coplanar with one another. A diameter of each second through hole  376  is less than a diameter of the second hollow. A diameter of the second hollow is substantially equal to a diameter of the cap portion  3582  of the corresponding buckling structure  358 . Thus the depressed collars  204  and the upraised collars  374  have essentially the same structure, with the depressed collars  204  being oriented symmetrically opposite the upraised collars  374 . 
     Referring also to  FIG. 8 , this shows engagement of the top plate  202  of the bezel  200  with the short side wall  352 , and engagement of the main body  3722  of the bottom plate  370  with the short side wall  352 , when the LCD device  2  is assembled. In a process of assembly of the LCD device  2 , the liquid crystal panel  210  is received in a first accommodating space cooperatively defined by the bezel  200  and the frame  350 . The BEF  322 , the diffusion film  321 , the LGP  333 , the reflector  360  are received in a second accommodating space cooperatively defined by the frame  350  and the bottom plate  370 . 
     The cap portions  3582  of the buckling structures  358  at the upsides  355  are vertically pressed into the first through holes  206  of the depressed collars  204 , and therefore are elastically deformed inwardly. The cap portion  3582  of each buckling structure  358  passes through the corresponding first through hole  206 . The cap portion  3582  then rebounds back to its original shape. The depressed collar  204  is thus substantially locked with the buckling structure  358  in the corresponding first notch  357 . With all the buckling structures  358  at the upsides  355  being locked with the corresponding depressed collars  204 , the top plate  202  firmly and securely abuts the upsides  355 . The bezel  200  is restricted from sliding or being pulled off the frame  350 . That is, relative movement of the bezel  200  and the frame  350  can be prevented. In this embodiment, the bezel  200  is locked with the frame  350 . 
     The cap portions  3582  of the buckling structures  358  at the underside  356  are vertically pressed into the second through holes  376  of the upraised collars  374 , and therefore are elastically deformed inwardly. The cap portion  3582  of each buckling structure  358  passes through the corresponding second through hole  376 . The cap portion  3582  then rebounds back to its original shape. The upraised collar  374  is thus substantially locked with the buckling structure  358  in the corresponding first notch  357 . With all the buckling structures  358  at the undersides  356  being locked with corresponding upraised collars  374 , the main body  372  firmly and securely abuts the undersides  356 . The bottom plate  370  is restricted from sliding or being pulled off the frame  350 . That is, relative movement of the bottom plate  370  and the frame  350  can be prevented. In this embodiment, the bottom plate  370  is locked with the frame  350 . 
     In summary, the bezel  200  is fixed to the frame  350  by engaging the depressed collars  204  with the corresponding buckling structures  358  of the short side walls  352 . A pressing operation generally in vertical directions only is needed. The bottom plate  370  is fixed to the frame  350  by engaging the upraised collars  374  with the corresponding buckling structures  358  of the short side walls  352 . A pressing operation generally in vertical directions only is needed. The bezel  200  and the backlight module  300  are therefore easily assembled into the LCD device  2 . When the LCD device  2  is disassembled, the cap portions  3582  of the buckling structures  358  are elastically deformed inwardly, and pressed through the corresponding first and second through holes  206 ,  376 . Thus each of the bezel  200  and the bottom plate  370  is detached from the frame  350 , and the LCD device  2  can be easily fully disassembled. In addition, when the LCD device  2  is in the assembled state, because the cap portions  3582  are elastic, essentially no interspaces exist where the depressed collars  204  are engaged with the corresponding buckling structures  358 , and essentially no interspaces exist where the upraised collars  374  are engaged with the corresponding buckling structures  358 . Thus the LCD device  2  has good mechanical stability. 
     In alternative embodiments, each buckling structure  358  can have any of various other suitable forms. For example, the buckling structure  358  can have a partially or fully split configuration. In such case, the cap portion  3582  can include a pair of generally semi-annular or arcuate parts oriented symmetrically opposite each other. Preferably, the semi-annular or arcuate parts are separated by a gap. Alternatively, the cap portion  3582  can include three arc-shaped parts symmetrically arranged about a center thereof. Preferably, the arc-shaped parts are separated by three corresponding gaps. In another alternative embodiment, the buckling structures  358  can be disposed at the bezel  200  and the bottom plate  370  respectively, and the depressed collars  204  and the upraised collars  374  can be disposed at the frame  350  correspondingly. 
     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.