Abstract:
An exemplary backlight module ( 200 ) used for liquid crystal display device ( 20 ) includes a first frame ( 261 ), a light source ( 240 ), a heat dispersing member ( 280 ) disposed along the light source, and a second frame ( 270 ) defining a window at a middle portion thereof. The second frame cooperative with the first frame to form a space receiving the light source and the heat dispersing member therein.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is related to, and claims the benefit of, a foreign priority application filed in China as Serial No. 200720120478.3 on Jun. 1, 2007. The related application is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to backlight modules typically used for liquid crystal display devices; and more particularly to a backlight module having a hollow bottom tray, and a liquid crystal display device incorporating the backlight module. 
     GENERAL BACKGROUND 
     Recently, liquid crystal display devices have been in widespread use as display devices for compact electronic apparatuses. Typical liquid crystal display devices not only provide good quality images with little power consumption, but also are very thin. The liquid crystal in a liquid crystal display device does not emit any light itself. The liquid crystal has to be lighted by a light source so as to clearly and sharply display text and images. Thus, a backlight module is generally needed for a liquid crystal display device. 
     Generally, a liquid crystal display device includes a top bezel, a plastic frame, and a bottom tray, whereby the top bezel, the plastic frame, and the bottom tray cooperatively form a space for receiving a liquid crystal panel and a backlight module. The bottom tray is made of alloy or metallic material with good heat transmission characteristics and high mechanical strength. 
     However, the alloy or metallic material of the bottom tray makes the backlight module and the liquid crystal display device incorporating the backlight module somewhat costly and heavy. 
     What is needed, therefore, is a backlight module and a liquid crystal display device incorporating the backlight module which can overcome the above-described deficiencies. 
     SUMMARY 
     In an exemplary embodiment, a backlight module includes a first frame, a light source, a heat dispersing member disposed along the light source, and a second frame defining a window at a middle portion thereof. The second frame cooperative with the first frame to form a space receiving the light source and the heat dispersing member therein. 
     In another exemplary embodiment, a liquid crystal display device includes a liquid crystal panel and a backlight module for illuminating the liquid crystal panel. The backlight module includes a frame, a light source comprising a lamp, a strip-shaped heat dispersing member positioned adjacent to the light source and corresponding to a length of the lamp, and a hollow tray. The hollow tray cooperates with the frame to form a space accommodating the light source and the heat dispersing member. 
     Other aspects, novel features and advantages will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of at least one embodiment of the present invention. In the drawings, like reference numerals designate corresponding parts throughout various views, and all the views are schematic. 
         FIG. 1  is an exploded, isometric view of a liquid crystal display device according to an exemplary embodiment of the present invention. 
         FIG. 2  is an assembled view of a backlight module of the liquid crystal display device of  FIG. 1   
         FIG. 3  is an enlarged, cross-sectional view taken along line III-III of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Reference will now be made to the drawings to describe preferred and exemplary embodiments of the present invention in detail. 
     Referring to  FIG. 1 , an exploded, isometric view of a liquid crystal display device according to an exemplary embodiment of the present invention is shown. The liquid crystal display device  20  includes a liquid crystal panel  210  and a backlight module  200 . The backlight module  200  is disposed under the liquid crystal panel  210  for illuminating the liquid crystal panel  210 . 
     The backlight module  200  includes a set of optical films  220 , a light guide plate  230 , a light source  240 , a reflective sheet  250 , a plastic frame  260 , a bottom tray  270 , and a heat dispersing plate  280 . The plastic frame  260  cooperates with the bottom tray  270  to form a space for receiving the set of optical films  220 , the light guide plate  230 , the light source  240 , the reflective sheet  250 , and the heat dispersing plate  280 . 
     The light guide plate  230  includes a top light input surface  231 , a light output surface  232  adjacent to the light input surface  231 , and a bottom surface  233 . The light source  240  includes a lamp  241 , and a reflective cover  242  receiving the lamp  241 . The reflective cover  242  includes a strip-shaped opening corresponding to the light input surface  231 . The lamp  241  may be a cold cathode fluorescent lamp. 
     The plastic frame  260  has a generally rectangular shape with a window at a middle portion thereof, and has four side portions  261 , four side walls  262 , and a plurality of catches  263  disposed at the side walls  262 . Each of the side walls  262  extends from one corresponding side portion  261 . The catches  263  are respectively disposed at outer surfaces of two opposite of the side walls  262 . 
     The bottom tray  270  also has a generally rectangular shape with a window at a middle portion thereof. The bottom tray  270  may be made of plastic material, a like material, or another suitable material. The bottom tray  270  includes a hollow bottom frame  271 , two side plates  272  upwardly extending from two opposite sides of the bottom frame  271 , and a plurality of catch holes  273  respectively disposed at outer surfaces of the side plates  272 . The catch holes  273  corresponding to the catches  263 . 
     The heat dispersing plate  280  is a thin plate with a rectangular shape, and may be made of aluminum material. The heat dispersing plate  280  has a length equal to that of the lamp  241 , and has a width larger than that of the reflective cover  242 . The width of the heat dispersing plate  280  may be equal to or larger than a quarter of a corresponding width of the bottom tray  270 . The heat dispersing plate  280  is capable of dispersing heat generated by the lamp  241  quickly, so as to keep the temperature of the lamp  241  within an acceptable range. 
     Also referring to  FIGS. 2-3 , in assembly of the liquid crystal display device  20 , the lamp  241  is received in the reflective cover  242 , and the reflective cover  242  is received in the bottom tray  270 . The opening of the reflective cover  242  is located at a lateral innermost side of the bottom tray  270 . The reflective sheet  250  is disposed on the bottom frame  271 , and one side portion of the reflective sheet  250  is received in the reflective cover  242 . The heat dispersing plate  280  is disposed between the reflective cover  242  and the reflective plate  250 . The heat dispersing plate  280  is attached to the reflective cover  242  so as to quickly disperse heat generated by the lamp  241 . The light guide plate  230  is disposed on the reflective sheet  250 , with the light input surface  231  located adjacent to the lamp  241 . The set of optical films  220  is disposed on the light output surface  232  of the light guide plate  230 . Each of the catches  263  of the plastic frame  260  engages in a corresponding one of the catch holes  273  of the bottom tray  270 , so as to tightly attach the plastic frame  260  and the bottom tray  270  together. Thereby, the plastic frame  260  and the bottom tray  270  cooperatively form a space accommodating the set of optical films  220 , the light guide plate  230 , the light source  240 , the reflective sheet  250 , and the heat dispersing plate  280 . 
     Unlike with a conventional backlight module, the bottom tray  270  defines a hollow portion. Thus the amount of material needed to fabricate the bottom tray  270  is reduced, and the cost of the bottom tray  270  is correspondingly low. In addition, when the bottom tray  270  is made of plastic material, the bottom tray  270  is correspondingly lightweight. Furthermore, the heat dispersing plate  280  is attached to the reflective cover  242  of the light source  240 , and can substitute for the bottom plate of a conventional bottom tray. Moreover, the heat dispersing plate  280  can quickly disperse heat generated by the lamp  241 . 
     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.