Abstract:
An exemplary backlight module ( 11 ) includes a light guide plate ( 12 ), a reflector ( 18 ), and a light emitting diode unit ( 142 ). The light guide plate has a light incident surface ( 122 ). The reflector is positioned adjacent to the light incident surface, and has a reflection pattern ( 184 ) thereat. The light emitting diode unit is interposed between the light incident surface and the reflector.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to backlight modules such as those used in liquid crystal displays (LCDs), and more particularly to a backlight module having a reflector which has a reflection pattern thereat.  
       GENERAL BACKGROUND  
       [0002]     Liquid crystal displays are commonly used as display devices for compact electronic apparatuses, because they not only provide good quality images but are also very thin. Because liquid crystal molecules in a liquid crystal display 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. Therefore, liquid crystal displays usually require a backlight module.  
         [0003]     Referring to  FIG. 12 , a typical backlight module  88  includes a light guide plate  880 , a light source  882 , and a reflector  884 , arranged in that order from right to left. The backlight module  88  further includes a plastic frame  886  for receiving the light guide plate  880 , the light source  882 , and the reflector  884 . The reflector  884  has a planar inner surface  885  facing the light source  882 . The light source  882  interposed between the light guide plate  880  and the reflector  884  includes a plurality of light emitting diode (LED) units  888 . Each LED unit  888  includes a red LED  888   a , a green LED  888   b , and a blue LED  888   c , and each LED  888   a / 888   b / 888   c  can emit light beams of the one respective particular kind of primary color.  
         [0004]     In operation, a mixing process of light beams occurs since each LED  888   a / 888   b / 888   c  emits one respective kind of light beams. The mixing process generally occurs in a space ranging from where the light beams emit from the LEDs  888   a ,  888   b , and  888   c  to where the light beams reach the light guide plate  880 , thus obtaining white light beams. However, the mixing space for the light beams is limited to a certain size of the plastic frame  886 , and the mixed light beams are therefore liable to appear a little yellow or blue, instead of being pure white. This may result in an uneven color balance of light output by the backlight module  88 . In order to obtain pure white light beams, the size of the plastic frame  886  is required to be large, which correspondingly increases a size of the backlight module  88 . This makes the backlight module  88  unsuitable for certain compact and small-scale applications.  
         [0005]     What is needed, therefore, is a backlight module that can overcome the above-described deficiencies. What is also needed is a liquid crystal display employing such a backlight module.  
       SUMMARY  
       [0006]     In one preferred embodiment, a backlight module includes a light guide plate, a reflector, and a light emitting diode unit. The light guide plate has a light incident surface. The reflector is positioned adjacent to the light incident surface, and has a reflection pattern thereat. The light emitting diode unit is interposed between the light incident surface and the reflector.  
         [0007]     Other aspects, advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     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.  
         [0009]      FIG. 1  is an exploded, side view of a liquid crystal display according to a first embodiment of the present invention, the liquid crystal display including a liquid crystal panel and a backlight module.  
         [0010]      FIG. 2  is a top plan view of the backlight module of the liquid crystal display of  FIG. 1 , the backlight module including a reflector.  
         [0011]      FIG. 3  is a top plan view of a reflector of a liquid crystal display according to a second embodiment of the present invention.  
         [0012]      FIG. 4  is a top plan view of a reflector of a liquid crystal display according to a third embodiment of the present invention.  
         [0013]      FIG. 5  is a top plan view of a reflector of a liquid crystal display according to a fourth embodiment of the present invention.  
         [0014]      FIG. 6  is a top plan view of a reflector of a liquid crystal display according to a fifth embodiment of the present invention.  
         [0015]      FIG. 7  is a top plan view of a reflector of a liquid crystal display according to a sixth embodiment of the present invention.  
         [0016]      FIG. 8  is a top plan view of a reflector of a liquid crystal display according to a seventh embodiment of the present invention.  
         [0017]      FIG. 9  is a top plan view of a reflector of a liquid crystal display according to an eighth embodiment of the present invention.  
         [0018]      FIG. 10  is a top plan view of a reflector of a liquid crystal display according to a ninth embodiment of the present invention.  
         [0019]      FIG. 11  is an exploded, side view of a liquid crystal display according to a tenth embodiment of the present invention.  
         [0020]      FIG. 12  is a top plan view of a conventional backlight module. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0021]     Reference will now be made to the drawings to describe the preferred embodiments in detail.  
         [0022]     Referring to  FIG. 1 , a liquid crystal display  1  according to a first embodiment of the present invention is shown. The liquid crystal display  1  includes a liquid crystal panel  15 , and a backlight module  11  adjacent to the liquid crystal panel  15 . Referring also to  FIG. 2 , the backlight module  11  includes a light guide plate  12 , a light source  14 , a diffusing film  16 , and a reflector  18 , arranged in that order from right to left. The backlight module  11  further includes a frame  19  for receiving the light guide plate  12 , the light source  14 , the diffusing film  16 , and the reflector  18 .  
         [0023]     The light source  14  interposed between the light guide plate  12  and the diffusing film  16  includes a plurality of LED units  142 . Each LED unit  142  includes a red LED  142   a , a green LED  142   b , and a blue LED  142   c . Each LED  142   a / 142   b / 142   c  can emit light beams of the one respective particular kind of primary color. Light beams emit from each LED  142   a / 142   b / 142   c  over a certain range of angles of divergence. When each LED  142   a / 142   b / 142   c  is viewed from above, the angle of divergence is generally in the range from 30 to 130 degrees, as measured from a front face of the LED  142   a / 142   b / 142   c . Each LED  142   a / 142   b / 142   c  is arranged such that its angle of divergence expands toward the diffusing film  16 . The reflector  18  includes an inner surface  182  facing the diffusing film  16 , and a pattern  184  formed at the inner surface  182 . The pattern  184  includes a plurality of reflective dots  186  outwardly extending from the inner surface  182 . The reflective dots  186  have many kinds of shapes and sizes. In the illuminated embodiment, the reflective dots  186  are arc-shaped; for example, the reflective dots  186  may be hemispherical, sub-hemispherical, semicylindrical, or sub-semicylindrical. The reflective dots  186  are irregularly arranged.  
         [0024]     In operation, light beams of one particular kind of primary color emit from each LED  142   a / 142   b / 142   c , transmit toward the diffusing film  16 , and reach the reflector  18  after being diffused by the diffusing film  16 . Light beams striking at the reflective dots  186  at the inner surface  182  of the reflector  18  are reflected in all directions, and finally reach a light incident surface  122  of the light guide plate  12  after being diffused again by the diffusing film  16 . A mixing process of light beams of different kinds of colors occurs since each LED  142   a / 142   b / 142   c  emits one kind of light beams, which mixing process occurs over a space up to where the mixed light beams reach the light guide plate  12 . Because the light beams are diffused by the diffusing film  16  and are reflected by the reflective dots  186  in all directions, light beams of red, green and blue (RGB) are fully mixed during this mixing process, thus obtaining enough pure white light beams where the mixed light beams reach the light guide plate  12 . This is achieved without requiring a larger sized backlight module with a larger mixing space. Therefore, optimized optical performance of the associated liquid crystal display  1  is also obtained, with the liquid crystal display  1  being able to be used in compact and small-scale applications.  
         [0025]     Referring to  FIG. 3 , a liquid crystal display  2  according to a second embodiment of the present invention is similar to the liquid crystal display  1 . However, a plurality of reflective dots  286  outwardly extend regularly from an inner surface  282  of a reflector  28  of the liquid crystal display  2 , and have many kinds of shapes and sizes.  
         [0026]     Referring to  FIG. 4 , a liquid crystal display  3  according to a third embodiment of the present invention is similar to the liquid crystal display  1 . However, a plurality of reflective dots  386  outwardly extend regularly from an inner surface  382  of a reflector  38  of the liquid crystal display  3 , with the reflective dots  386  having a same shape and a same size.  
         [0027]     Referring to  FIG. 5 , a liquid crystal display  4  according to a fourth embodiment of the present invention is similar to the liquid crystal display  1 . However, a plurality of reflective dots  486  outwardly extend irregularly from an inner surface  482  of a reflector  48  of the liquid crystal display  4 , with the reflective dots  486  having a same shape and a same size.  
         [0028]     Referring to  FIG. 6 , a liquid crystal display  5  according to a fifth embodiment of the present invention is similar to the liquid crystal display  1 . However, a plurality of continuous reflective dots  586  inwardly extend irregularly from a transparent inner surface  582  of a reflector  58  of the liquid crystal display  5 , and have many kinds of shapes and sizes. That is, the reflective dots  586  are in the form of depressions in the inner surface  582 .  
         [0029]     Referring to  FIG. 7 , a liquid crystal display  6  according to a sixth embodiment of the present invention is similar to the liquid crystal display  5 . However, a plurality of continuous and discontinuous reflective dots  686  inwardly extend irregularly from a transparent inner surface  682  of a reflector  68  of the liquid crystal display  6 , and have many kinds of shapes and sizes.  
         [0030]     Referring to  FIG. 8 , a liquid crystal display  7  according to a seventh embodiment of the present invention is similar to the liquid crystal display  5 . However, a plurality of continuous reflective dots  786  inwardly extend regularly from a transparent inner surface  782  of a reflector  78  of the liquid crystal display  7 , with the reflective dots  786  having a same shape and a same size.  
         [0031]     Referring to  FIG. 9 , a liquid crystal display  8  according to an eighth embodiment of the present invention is similar to the liquid crystal display  7 . However, a plurality of continuous and discontinuous reflective dots  896  inwardly extend irregularly from a transparent inner surface  892  of a reflector  89  of the liquid crystal display  8 , with the reflective dots  896  having a same shape and a same size.  
         [0032]     Referring to  FIG. 10 , a liquid crystal display  9  according to a ninth embodiment of the present invention is in effect a hybrid of the liquid crystal display  2  and the liquid crystal display  5 . In the liquid crystal display  9 , a plurality of reflective dots  986  extend both outwardly and inwardly from an inner surface  982  of a reflector  98  of the liquid crystal display  9 . The reflective dots  986  have many kinds of shapes and sizes.  
         [0033]     Referring to  FIG. 11 , a liquid crystal display according to a tenth embodiment of the present invention is shown. The liquid crystal display  10  includes an upper liquid crystal panel  100 , an upper light guide plate  101 , a middle reflector  102 , a lower light guide plate  103 , and a lower liquid crystal panel  104 , arranged in that order from top to bottom. The liquid crystal display  10  further includes a side reflector  106  located adjacent to the middle reflector  102 , and a light source  107  interposed between the middle reflector  102  and the side reflector  106 . The side reflector  106  can be any one of the above-described reflectors  18 ˜ 78 ,  89 ,  98  of the first through ninth embodiments. The liquid crystal display  10  can be used for double-sided displaying, and has advantages similar to those of the above-described liquid crystal displays  1  through  9 .  
         [0034]     Further or alternative embodiments may include the following. In one example, each LED can instead be another kind of point illuminator that has a certain angle of divergence.  
         [0035]     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 or scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.