Patent Publication Number: US-2013235615-A1

Title: Light guide plate and backlight module using same

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a light guide plate and a backlight module using the light guide plate. 
     2. Description of Related Art 
     Backlight modules often include a light guide plate and a number of spaced light sources. The light guide plate includes a light incident surface and a top surface perpendicular to the light incident surface. The top surface includes an effective light emitting surface at a central portion thereof. The light sources are positioned adjacent to the light incident surface. Dark areas are formed between the spaced light sources because the light rays from the light sources cannot properly light the spaces, therefore, the brightness of the light incident surface is not uniform, additionally, without a defined microstructure in the light incident surface, even though the light rays from the light sources pass through the light guide plate, the brightness of the light emitting area is also not uniform. 
     Therefore, it is desirable to provide a light guide plate and a backlight module that can overcome the above-mentioned limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the embodiments should be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic view of a backlight module, according to an exemplary embodiment, the backlight module including a light guide plate. 
         FIG. 2  is a schematic view of the light guide plate of  FIG. 1 , the light guide plate including a number of protrusions. 
         FIG. 3  is a schematic view of each of the protrusions of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-2 , a backlight module  100 , according to an embodiment, includes a light guide plate  10  and a number of light sources  20 . In this embodiment, the light sources  20  are light emitting diodes (LEDs). 
     The light guide plate  10  is made of transparent material (such as acrylic resin or polyethylene resin), and includes a main body  101  and a number of semi-cylindrical protrusions  111 . In this embodiment, the main body  101  and the protrusions  111  are integrally formed. 
     The main body  101  includes a light incident surface  11 , a bottom surface  13 , a top surface  15 , and a side surface  17 . The bottom surface  13  is substantially parallel to the top surface  15 . The light incident surface  11  is connected to the top surface  15  and the bottom surface  13 . The light incident surface  11  is substantially perpendicular to the top surface  15 . The side surface  17  is connected to the top surface  15  and the bottom surface  13 , and is at an opposite side of the light guide plate  10  to the light incident surface  11 . In other embodiments, the bottom surface  13  can be inclined with respect to the top surface  15 . 
     The top surface  15  includes a light emitting area  151  (indicated by broken line) and a fringe area  152  surrounding the light emitting area  151 . 
     The light sources  20  face the light incident surface  11 . The light incident surface  11  transmits light rays from the light sources  20  into the light guide plate  10 . The bottom surface  13  and the side surface  17  respectively internally reflect the light rays in the light guide plate  10 . The light emitting area  151  transmits a portion of the light rays incident thereon to the exterior above the light guide plate  10 , and reflects the other portion of the light rays incident thereon back into the light guide plate  10 . 
     Referring to  FIG. 3 , the protrusions  111  are continuously distributed on the light incident surface  11 . Each of the protrusions  111  is substantially semi-cylindrical, and includes two opposite semicircular end surfaces  112 , an arc-shaped peripheral surface  113 , and a plane-shaped fixed surface  114 . The peripheral surface  113  is connected to the two end surfaces  112  and the fixed surface  114 . The fixed surface  114  is opposite to the peripheral surface  113 , and is perpendicular to the two end surfaces  112 . The fixed surface  114  is positioned on the light incident surface  11 , and a central axis of the protrusion  111  is perpendicular to the top surface  15 . The length L of each protrusion  111  along its central axis is substantially equal to the thickness T of the light incident surface  11  along a direction perpendicular to the top surface  15 . A radius R of each of the end surfaces  112  is more than 0 millimeters (mm) and less than 1 mm. In this embodiment, R is substantially equal to 0.04 micrometers (μm). 
     In use, the protrusions  111  diffuse the light rays from the light sources  20  in a way that ensure the light rays uniformly strike the light emitting area  151  such that the brightness of the light emitting area  151  becomes uniform. 
     It will be understood that the above particular embodiments and methods are shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.