Abstract:
A backlight module ( 2 ) includes a light source ( 66 ) and a light guide plate ( 20 ), the light guide plate includes a light incidence surface ( 25 ), a light-emitting surface ( 21 ) adjacent to the light incidence surface; and a bottom surface ( 22 ) opposite to the light-emitting surface, the bottom surface includes a plurality of curved grooves ( 23 ), the light-emitting surface includes a plurality of grooves ( 24 ). In the backlight module, because of the curved grooves of the bottom surface and the grooves of the light-emitting surface, light beams entering the light guide plate are concentrated at the bottom surface and light-emitting surface, thus the surface light beams outputting from the light-emitting surface have a rather higher brightness.

Description:
BACKGROUND  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to light guide plates and backlight modules that use light guide plates, such backlight modules typically being incorporated into devices such as liquid crystal displays.  
         [0003]     2. General Background  
         [0004]     In a typical liquid crystal display, a backlight module provides a surface light source for illuminating the liquid crystal display. Generally, the backlight module includes a light guide plate and a light source arranged adjacent to one side of the light guide plate. The light guide plate changes light beams received from the light source into surface light beams, and directs the surface light beams to a liquid crystal panel of the liquid crystal display.  
         [0005]      FIG. 13  shows a conventional backlight module  1 . The backlight module  1  comprises a light guide plate  10  and a point light source  13  adjacent to a corner of the light guide plate  10 . The light guide plate  10  includes a bottom surface  11 . The bottom surface  11  has a plurality of curving grooves  12 . Each of the curving grooves  12  is bounded by a pair of ridges, and each of the ridges is continuous along a length thereof. Generally the curving grooves  12  are concentric relative to the point light source  13 .  
         [0006]     In operation, light beams emitted from the point light source  13  propagate within the light guide plate  10  toward the curving grooves  12  in directions perpendicular to the curving grooves  12 . The light beams are reflected and refracted at the curving grooves  12 , and are then output from a light-emitting region (not shown) of the light guide plate  10 . With this configuration, the light beams output from the light-emitting region provide improved brightness and uniformity of illumination.  
         [0007]     However, there is ongoing demand for backlight modules to provide even more improved brightness and uniformity of illumination. A new light guide plate for a backlight module which can meet this demand is desired.  
       SUMMARY  
       [0008]     A light guide plate according to one embodiment of the invention comprises a light source and a light guide plate. The light guide plate includes a light incidence surface, a light-emitting surface adjacent to the light incidence surface; and a bottom surface opposite to the light-emitting surface. The bottom surface includes a plurality of curved grooves, and the light-emitting surface includes a plurality of grooves.  
         [0009]     The backlight module has the following advantages. In one embodiment of the invention, light beams from the light source pass through the light incidence surface and enter the light guide plate, reflect and refract in the light guide plate, and finally the surface light beams output from the light-emitting surface. When the light beams reach the bottom surface of the light guide plate, the curved grooves on the bottom surface concentrate the light beams and enhance brightness of the light beams. Then the light beams reach the light-emitting surface, and are further concentrated by the grooves on the light-emitting surface again, thus surface light beams outputting from the light-emitting surface have a relatively high brightness.  
         [0010]     Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a schematic, isometric view of a light guide plate according to a first embodiment of the present invention;  
         [0012]      FIG. 2  is an inverted, isometric view of the light guide plate of  FIG. 1 ;  
         [0013]      FIG. 3  is a side plan view of the light guide plate shown in  FIG. 1 ;  
         [0014]      FIG. 4  is a schematic, top plan view of the light guide plate of  FIG. 1 , showing a light-emitting surface thereof;  
         [0015]      FIG. 5  is a schematic, bottom plan view of the light guide plate of  FIG. 1 , showing a bottom surface thereof;  
         [0016]      FIG. 6  is a schematic, plan view of a bottom surface of a light guide plate according to a second embodiment of the present invention;  
         [0017]      FIG. 7  is a schematic, plan view of a bottom surface of a light guide plate according to a third embodiment of the present invention;  
         [0018]      FIG. 8  is a schematic, plan view of a bottom surface of a light guide plate according to a fourth embodiment of the present invention;  
         [0019]      FIG. 9  is a schematic, isometric view of a first embodiment of a backlight module according to the present invention, the backlight module comprising the light guide plate of  FIG. 1 ;  
         [0020]      FIG. 10  is a schematic, bottom plan view of a second embodiment of a backlight module according to the present invention, the backlight module comprising the light guide plate of  FIG. 6 ;  
         [0021]      FIG. 11  is a schematic, bottom plan view of a third embodiment of a backlight module according to the present invention, the backlight module comprising the light guide plate of  FIG. 7 ;  
         [0022]      FIG. 12  is a schematic, bottom plan view of a fourth embodiment of a backlight module according to the present invention, the backlight module comprising the light guide plate of  FIG. 8 ; and  
         [0023]      FIG. 13  is a schematic, bottom plan view of a conventional backlight module. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     Referring to  FIG. 1  through  FIG. 5 , a plate-like light guide member  20  according to the first embodiment of the invention includes a light incidence surface  25 , a light-emitting surface  21  adjacent to the light incidence surface  25 , and a bottom surface  22  opposite to the light-emitting surface  21 . A plurality of parallel, circular arc grooves  23  are defined at the bottom surface  22 . The circular arc grooves  23  have widths in a range from 10 −6  meters to 10 −8  meters. Each of the circular arc grooves  23  is bounded by two parallel ridges of the light guide plate  20 . Each of the ridges has a similar shape, and is continuous along a length thereof. An overall shape of each circular arc groove  23  is part of a corresponding imaginary circle. The circular arc grooves  23  are generally concentric relative to a reference point  26 , which is located outside the light guide plate  20  opposite to a middle of the light incidence surface  25 . The light guide plate  20  having the circular arc grooves  23  may be simultaneously formed as a single body. A cross-sectional type view of each circular arc groove  23  defines a V-shape, which includes two sides  231  and  232  of two corresponding ridges of the light guide plate  20 . The side  232  generally faces toward the light incidence surface  25 . An angle α is defined between the side  232  and the bottom surface  22 . The angle α of successive sides  232  of the light guide plate  20  progressively increases with increasing distance away from the light incidence surface  25 . The light-emitting surface  21  has a plurality of linear V-cuts  24  defined thereat. The V-cuts  24  are parallel to one another.  
         [0025]     Referring to  FIG. 6 , a light guide plate  30  according to the second embodiment of the invention is shown. The light guide plate  30  includes a light incidence surface (not visible), a light-emitting surface (not visible) adjacent to the light incidence surface, and a bottom surface  32  opposite to the light-emitting surface. A plurality of circular arc grooves  33  are defined at the bottom surface  32 , and a plurality of V-cuts (not visible) are defined at the light incidence surface. An overall shape of each circular arc groove  33  is part of a corresponding imaginary circle. Each of the circular arc grooves  33  is bounded by two parallel ridges of the light guide plate  20 . Each of the ridges has a uniform shape, but is discontinuous to form a plurality of discontinuous units along a length thereof. The circular arc grooves  33  generally are concentric relative to a reference point  36 , which is located outside the light guide plate  30  opposite to a middle of the light incidence surface. Discontinuous ridges that are adjacent each other across an intervening circular arc groove  33  may be arranged directly opposite each other, or may be arranged in staggered fashion opposite each other. In the illustrated embodiment, discontinuous ridges near the reference point  36  are mostly arranged in staggered fashion opposite each other, and discontinuous ridges distal from the reference point  36  are mostly arranged directly opposite each other.  
         [0026]     As shown in  FIG. 7 , a light guide plate  40  according to the third embodiment of the invention is similar in principle to the light guide plate  30 . The light guide plate  40  includes a light incidence surface  45 , a bottom surface  42 , and a plurality of circular arc grooves  43  at the bottom surface  42 . A reference point  46  of the circular arc grooves  43  is disposed outside a corner of the light incidence surface  45 .  
         [0027]     As shown in  FIG. 8 , a light guide plate  50  according to the fourth embodiment of the invention is somewhat similar in principle to the light guide plate  30 . The light guide plate  50  includes a bottom surface  52 , and a plurality of concentric circular arc grooves  53  at the bottom surface  52 . A center  56  of the circular arc grooves  53  is at a center of the bottom surface  52 .  
         [0028]      FIG. 9  shows a first embodiment of a backlight module of a display device according to the present invention. The backlight module  2  includes the light guide plate  20 , and a light source  66  opposite to a middle of the light incidence surface  25  of the light guide plate  20 . That is, the light source  66  locates at the reference point  26  of the circular arc grooves  23  of the bottom surface  22  of the light guide plate  20 . The light source  66  is, for example, a light emitting diode.  
         [0029]     When the backlight module  2  operates, light beams from the light source  66  pass through the light incidence surface  21  and enter the light guide plate  20 . The light beams are reflected and refracted in the light guide plate  20 , and finally surface light beams are output from the light-emitting surface  21 . When light beams within the light guide plate  20  reach the bottom surface  22 , the circular arc grooves  23  of the bottom surface  22  concentrate the light beams and enhance their brightness. In addition, when light beams reach the light-emitting surface  21 , they are concentrated by the V-cuts  24 . Thus the surface light beams output from the light-emitting surface  21  have a relatively high brightness.  
         [0030]      FIG. 10  shows a second embodiment of a backlight module according to the present invention. The backlight module  3  includes the light guide plate  30  and a light source  66 . The light source  66  is arranged opposite to a middle of the light incidence surface  35 . In the backlight module  3 , the ridges bounding the circular arc grooves  33  are discontinuous, and many discontinuous ridges that are adjacent each other across an intervening circular arc groove  33  are arranged in staggered fashion opposite each other. Therefore the circular arc grooves  33  can refract light beams within the light guide plate  30  in good quantity, and output light beams having improved uniformity can be obtained.  
         [0031]      FIG. 11  shows a third embodiment of a backlight module of a display device according to the present invention. The backlight module  4  includes the light guide plate  40  and a light source  66 . The light source  66  is disposed outside a corner of the light incidence surface  45 . In particular, the light source  66  is disposed at the reference point  46  of the circular arc grooves  43 .  
         [0032]      FIG. 12  shows a fourth embodiment of a backlight module according to the present invention. The backlight module  5  includes the light guide plate  50  and a light source  66 . The light source  66  is disposed at the center of the bottom surface  52 .  
         [0033]     In summary, the backlight module  2  taken as an exemplary embodiment has the following advantages. Light beams from the light source  66  pass through the light incidence surface  25  and enter the light guide plate  20 , and are reflected and refracted within the light guide plate  20 . Finally, surface light beams are output from the light-emitting surface  21 . When the light beams reach the bottom surface  22  of the light guide plate  20 , the circular arc grooves  23  at the bottom surface  22  concentrate the light beams and enhance a brightness of the light beams. These brighter light beams reach the light-emitting surface  21 , and are further concentrated by the V-cuts  24  of the light-emitting surface  21 . Thus surface light beams output from the light-emitting surface  21  have high brightness.  
         [0034]     Furthermore, the inventive light guide plate and backlight module are not limited to the embodiments described above. For example, grooves at the bottom surface and at the light-emitting surface of the light guide plate may define a cross-section that is generally trapezoidal, trapezium-shaped, arcuate, arch-shaped, and so on. The angle or angles defined by the grooves and the bottom surface may be configured according to the brightness and other characteristics of the light source used.  
         [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 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.