Patent Document

FIELD OF THE INVENTION 
     The present invention relates to backlight modules and liquid crystal displays (LCDs) that include backlight modules, and more particularly to backlight modules configured to avoid being noisy. 
     GENERAL BACKGROUND  
     Liquid crystal displays are commonly used as display devices for compact electronic apparatuses, because they not only provide good quality images with little power but are also very thin. The liquid crystal molecules in a liquid crystal display device do not emit any light themselves. The liquid crystal molecules have to be lit 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. 
     In a typical such liquid crystal display, the backlight module includes a plastic frame and a light guide plate positioned in the plastic frame. The light guide plate includes a plurality of ears integrally extending from a side surface thereof. The ears are respectively received in a plurality of notches of the plastic frame. Contact portions of the ears of the light guide plate and of walls that bound the notches of the plastic frame are generally planar surfaces. The contact portions of the ears and the notch walls are liable to rub against each other when the liquid crystal display is subjected to vibration or shock during operation or transportation. When this friction occurs, the liquid crystal display is liable to be noisy. 
     What is needed, therefore, is a backlight module that can overcome the above-described deficiencies. What is also need is a liquid crystal display employing such a backlight module. 
     SUMMARY  
     In a preferred embodiment, a backlight module includes a frame and a light guide plate positioned in the frame. The frame defines a notch, which notch is bounded by a wall of the frame. The light guide plate includes a side surface, and an ear extending from the side surface. The ear is received in the notch. A first protrusion protrudes from either the wall of the notch or the ear and contacts the corresponding ear or wall of the notch. 
     Other advantages and novel features 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 a liquid crystal display including a backlight module according to a first embodiment of the present invention. 
         FIG. 2  is an assembled view of the liquid crystal display of  FIG. 1 . 
         FIG. 3  is an enlarged, cross-sectional view taken along line III-III of  FIG. 2 . 
         FIG. 4  is similar to  FIG. 3 , but showing a corresponding view in the case of a liquid crystal display including a backlight module according to a second embodiment of the present invention. 
         FIG. 5  is similar to  FIG. 3 , but showing a corresponding view in the case of a liquid crystal display including a backlight module according to a third embodiment of the present invention. 
         FIG. 6  is similar to  FIG. 3 , but showing a corresponding view in the case of a liquid crystal display including a backlight module according to a fourth embodiment of the present invention. 
         FIG. 7  is similar to  FIG. 3 , but showing a corresponding view in the case of a liquid crystal display including a backlight module according to a fifth embodiment of the present invention. 
         FIG. 8  is similar to  FIG. 7 , but showing a corresponding view in the case of a liquid crystal display including a backlight module according to a sixth embodiment of the present invention. 
         FIG. 9  is similar to  FIG. 7  , but showing a corresponding view in the case of a liquid crystal display including a backlight module according to a seventh embodiment of the present invention. 
         FIG. 10  is similar to  FIG. 7 , but showing a corresponding view in the case of a liquid crystal display including a backlight module according to an eighth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Reference will now be made to the drawings to describe the preferred embodiments in detail. 
     Referring to  FIG. 1 , a liquid crystal display  1  according to a first embodiment of the present invention includes a top bezel  10 , a liquid crystal panel  12 , a light guide plate  14 , and a frame  16 , disposed in that order from top to bottom. 
     The top bezel  10  includes a top wall  102 , and two opposite first side walls  104  integrally connecting with the top wall  102 . The top wall  102  defines a rectangular first opening (not labeled), corresponding to a display area (not labeled) of the liquid crystal panel  12 . The first side walls  104  perpendicularly extend down from opposite long sides (not labeled) of the top wall  102  respectively. Each first side wall  104  defines two hatches  106  therein. The top bezel  10  can be made from iron, aluminum, magnesium, or any other suitable metal or alloy. 
     Referring also to  FIG. 2  and  FIG. 3 , the light guide plate  14  includes two opposite side surfaces  141 , a first top surface  142  perpendicularly adjoining the two side surfaces  141 , and a first bottom surface  143  opposite to the first top surface  142 . Two rectangular first ears  144  integrally extend from each side surface  141 . Each first ear  144  includes a second top surface  145 , and a second bottom surface  146  opposite to the second top surface  145 . The second top surface  145  is coplanar with the first top surface  142 . The second bottom surface  146  of the first ear  144  is planar. The first bottom surface  143 , the second bottom surface  146 , and a side surface (not labeled) adjoining the first bottom surface  143  and the second bottom surface  146  cooperatively define a step. The light guide plate  14  can be made from polycarbonate (PC) or polymethyl methacrylate (PMMA), and can be manufactured by an injection molding method. 
     The frame  16  includes a bottom wall  161 , and two second side walls  162  integrally connecting with the bottom wall  161 . The bottom wall  161  is generally frame-shaped, and defines a rectangular second opening (not labeled) for light from below the liquid crystal display  1  to reach the light guide plate  14 . Each second side wall  162  has a generally asymmetrical U-shape. The second side walls  162  extend perpendicularly up from two opposite sides (not labeled) of the bottom wall  161 , and are symmetrically opposite each other. Outmost vertical faces of the second side walls  162  are coplanar with corresponding outmost vertical faces of the bottom wall  161 . Each second side wall  162  includes a first arm  1620 , a second arm  1622 , and a third arm  1624 . Each first arm  1620  extends along a corresponding long side of the frame  16 . The corresponding second arm  1622  and third arm  1624  respectively extend perpendicularly inward in a same direction from two opposite ends (not labeled) of the first arm  1620 . The third arm  1624  is longer than the second arm  1622 . The second arms  1622  of the opposite second side walls  162  are opposite to each other, and the third arms  1624  of the opposite second side walls  162  are opposite to each other. Each first arm  1620  includes two first protrusions  163  integrally extending perpendicularly outward from the outmost vertical face thereof. 
     The frame  16  further defines two pairs of first notches  164 , positioned at two opposite inner long sides (not labeled) of the bottom wall  161  respectively. Each first notch  164  is located opposite to one respective first protrusion  163 . Each first ear  144  of the light guide plate  14  is received in one respective first notch  164 . A flat third bottom surface  166  that bounds each first notch  164  is parallel to and close to the second bottom surface  146  of the corresponding first ear  144 . A plurality of second protrusions  165  (only one shown) integrally protrude from the third bottom surface  166  and contact the second bottom surface  146 . The second protrusions  165  can be generally dome shaped or generally linear. Each second protrusion  165  has an arc-shaped cross-sectional configuration; for example, the second protrusion  165  may be hemispherical, sub-hemispherical, semicylindrical, or sub-semicylindrical. The frame  16  is preferably made from plastic or any other suitable polymer. 
     When the liquid crystal display  1  is assembled, the top bezel  10  and the frame  16  cooperatively accommodate the liquid crystal display  12  and the light guide plate  14  therebetween. The hatches  106  engagingly receive the first protrusions  163  therein, thereby locking the top bezel  10  and the frame  16  together. The first notches  164  of the frame  16  respectively receive the first ears  144  of the light guide plate  14  therein, and the second protrusions  165  at the first notches  164  contact the second bottom surfaces  146  of the first ears  144 . Thus, the above-described configuration can help to greatly enhance frictional engagement of the first ears  144  in the first notches  164 . That is, there is considerable resistance to relative movement as between the first ears  144  and the frame  16 . Therefore the liquid crystal display  1  can avoid being noisy when it is subjected to vibration or shock during operation or transportation. 
     Referring to  FIG. 4 , a liquid crystal display  2  according to a second embodiment of the present invention is similar to the liquid crystal display  1  of the first embodiment. However, each of third protrusions  165  of the liquid crystal display  2  has a rectangular cross-sectional configuration. 
     Referring to  FIG. 5 , a liquid crystal display  3  according to a third embodiment of the present invention is similar to the liquid crystal display  1  of the first embodiment. However, each of fourth protrusions  365  of the liquid crystal display  3  has a triangular cross-sectional configuration. 
     Referring to  FIG. 6 , a liquid crystal display  4  according to a fourth embodiment of the present invention is similar to the liquid crystal display  1  of the first embodiment. However, each of fifth protrusions  465  of the liquid crystal display  4  has a trapezoidal cross-sectional configuration. 
     Referring to  FIG. 7 , a liquid crystal display  5  according to a fifth embodiment of the present invention is similar to the liquid crystal display  1  of the first embodiment. However, in the liquid crystal display  5 , a fourth bottom surface  565  of each of second notches  564  is planar. A plurality of sixth protrusions (only one shown)  546  integrally protrude from a fifth bottom surface  547  of each of fifth ears  544 . The fourth bottom surface  565  at each second notch  564  contacts the sixth protrusions  546  of the corresponding fifth ear  544 . The sixth protrusions  546  can be generally dome shaped or generally linear. Each sixth protrusion  546  has an arc-shaped cross-sectional configuration; for example, the sixth protrusion  546  may be hemispherical, sub-hemispherical, semicylindrical, or sub-semicylindrical. 
     Referring to  FIG. 8 , a liquid crystal display  6  according to a sixth embodiment of the present invention is similar to the liquid crystal display  5  of the fifth embodiment. However, each of seventh protrusions  646  of the liquid crystal display  6  has a rectangular cross-sectional configuration. 
     Referring to  FIG. 9 , a liquid crystal display  7  according to a seventh embodiment of the present invention is similar to the liquid crystal display  5  of the fifth embodiment. However, each of eighth protrusions  746  of the liquid crystal display  7  has a triangular cross-sectional configuration. 
     Referring to  FIG. 10 , a liquid crystal display  8  according to an eighth embodiment of the present invention is similar to the liquid crystal display  5  of the fifth embodiment. However, each of ninth protrusions  846  of the liquid crystal display  8  has a trapezoidal cross-sectional configuration. 
     Further and/or alternative embodiments may include the following. A plurality of generally linear prisms may be defined at the first top surface  142  of the light guide plate  14 . A reflective sheet may be disposed adjacent to the first bottom surface  143  of the light guide plate  14 . A linear light source or a plurality of point light sources may be disposed adjacent to an underside of the light guide plate  14 . In any of the above-described first through fourth embodiments or alternative embodiments, only a single protrusion may be provided at the bottom surface that bounds each notch of the frame. Similarly, in any of the above-described fifth through eighth embodiments or alternative embodiments, only a single protrusion may be provided at the bottom surface of each ear of the light guide plate. In any of the above-described first through eighth embodiments or alternative embodiments, the protrusions may protrude from both the bottom surfaces that bound the notches and from the ears, and frictionally contact each other. 
     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.

Technology Category: 3