Patent Publication Number: US-2005140850-A1

Title: Edge backlight module and liquid crystal display utilizing the same

Description:
BACKGROUND  
      1. Field of the Invention  
      The present invention relates to an edge backlight module and a liquid crystal display utilizing the same.  
      2. Description of the Related Art  
      Generally, an LCD comprises a liquid crystal panel and a backlight module. The liquid crystal panel is the display of the LCD. Since the liquid crystal panel does not emit light, a light source providing sufficient brightness and uniform distribution is required to properly display images. A backlight module serves as the light source for the LCD.  
      Generally, backlight modules can be categorized as direct and edge structures. In direct backlight modules the light source is disposed directly in the cavity of the backlight module, thus occupying a relatively larger volume thereof. In edge backlight modules (also referred to as side-light modules), the light source is disposed on a side of the backlight module to reduce volume thereof, and a light guide plate guides the light toward the liquid crystal panel.  
       FIG. 1  is an exploded view showing a conventional edge backlight module. In  FIG. 1 , the conventional edge backlight module  1  comprises a frame  11 , light dispersing films  12 , a light guide plate  13 , a reflective plate  14 , a back plate  15 , and two light source modules  16  disposed at each side of the edge backlight module  1  respectively. Each light source module  16  comprises at least one lamp as the light source  161 , a light source reflector  162 , a rubber bushing  163  to fix the light source  161 , cables  164  and connectors  165  for connecting and driving the light source  161 . During assembly, the reflective plate  14 , the light guide plate  13 , the light dispersing films  12  and the frame  11  are sequentially attached to the back plate  15 , and light source modules  16  are disposed on each side of the edge backlight module  1  in the clearance between the light guide plate  13  and the back plate  15 .  
      The light source module  16  shown in  FIG. 1  is described in detail with reference to a cross-section thereof shown in  FIG. 2 . In  FIG. 2 , the reflective plate  14  backs only a portion of the light source module  16 . Thus, the light source reflector  162  enclosing the light source  161  is required to prevent light leakage. The light source reflector  162  is a C-shaped structure connected to the end portions of the light guide plate  13  and the reflective plate  14 . Thus, a cavity  17  is formed between the light source reflector  162 , the reflective plate  14  and the light guide plate  13 . Light emitted from the light source  161  is reflected in the cavity  17  to the light guide plate  13  without leaking out.  
      The light source reflector  162  is a separate element, however, and is difficult to accurately position during assembly. Further, additional reflective materials are required in manufacturing the light source reflector  162 , increasing material consumption.  
     SUMMARY OF THE INVENTION  
      Accordingly, an object of the present invention is to provide an edge backlight module with fewer elements in the light source module, thus simplifying positioning during assembly.  
      The present invention discloses an edge backlight module. The edge backlight module comprises a light source module, a light guide plate, and a reflective back plate. The reflective back plate has a reflective surface and at least one wraparound end. The light guide plate is disposed at the reflective surface of the reflective back plate, and an end of the light guide plate is connected to the wraparound end forming a cavity therebetween. The light source module is disposed in the cavity. A reflective layer can be fabricated by die casting or coated on the reflective surface of the reflective back plate.  
      Further, the present invention discloses a liquid crystal display. The LCD comprises a liquid crystal panel and the above-mentioned edge backlight module, with the reflective surface of the reflective back plate facing the liquid crystal panel. Further, the LCD comprises a bezel at the side of the liquid crystal panel enclosing the edge backlight module.  
      According to the present invention, the reflective surface of the reflective back plate extends to the light source module, and the wraparound end of the reflective back plate encloses the end of the light guide plate forming a cavity for the light source module. Thus simplifying the structure of the light source module, and enabling accurate positioning of the elements during assembly.  
      A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:  
       FIG. 1  is an exploded view of a conventional edge backlight module  1 ;  
       FIG. 2  is a cross-section of a portion of the conventional edge backlight module  1  along line A-A in  FIG. 1 ;  
       FIG. 3  is an exploded view of the edge backlight module  2  of the present invention; and  
       FIG. 4  is a cross-section of a portion of the edge backlight module  2  along line B-B in  FIG. 3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention relates to an edge backlight module. The edge backlight module of the present invention is described hereinafter with reference to  FIG. 3 .  
      In  FIG. 3 , the edge backlight module  2  comprises a frame  21 , light dispersing films  22 , a light guide plate  23 , a reflective back plate  25 , and two light source modules  26  disposed at each side of the edge backlight module  2 . The reflective back plate  25  of the present invention is an individual element rather than the separate reflective plate  14  and back plate  15  as shown in  FIG. 1 . Each light source module  26  has at least one lamp serving as the light source  261 , a rubber bushing  263  to fix the light source  261 , and cables  264  and connectors  265  for connecting and driving the light source  261 .  
      During assembly, the light guide plate  23 , the light dispersing films  22  and the frame  21  are sequentially attached to the reflective back plate  25 , and the light source modules  26  are inserted on each side of the edge backlight module  2  in the cavity  27  between the light guide plate  23  and the reflective back plate  25 .  
      The light source module  26  in  FIG. 3  can be described in detail with reference to  FIG. 4 . In  FIG. 4 , the reflective back plate  25  comprises a reflective surface S 1 , and a wraparound end  253  facing the reflective surface S 1 . The reflective surface S 1  can be formed by coating or die casting of reflective materials. Specifically, the reflective back plate  25  can be obtained by coating or die-casting a reflective layer  251  on a flat plate  252  to form the reflective surface S 1 , and punching or pressing the flat plate  252  to form the wraparound end  253 .  
      The light guide plate  23  is disposed and attached to the reflective surface S 1  of the reflective back plate  25 , and an end of the light guide plate  23  is connected to the wraparound end  253 , such that a cavity  27  is formed between the end of the light guide plate  23  and the wraparound end  253 . Thus, the light source module  26  is inserted in the cavity  27  without requiring the light source reflector  162  shown in  FIG. 1 .  
      Since the reflective surface S 1  is extended to the inner surface of the wraparound end  253 , light emitted from the light source  261  is reflected in the cavity  27  to the light guide plate  23  without leaking out.  
      The edge backlight module  2  in the embodiment can be applied in a liquid crystal display or any other display requiring a backlight module. Specifically, a liquid crystal panel is provided, and the edge backlight module  2  is disposed at a side of the liquid crystal panel with the reflective surface S 1  facing the liquid crystal panel. A bezel can be further provided to enclose the edge backlight module  2 .  
      According to the present invention, the reflective back plate  25  is extended to form the wraparound end  253 , which encloses the end of the light guide plate  23  to form the cavity  27  enclosing the light source module  27 . Thus simplifying the structure of the light source module  27  and enabling accurate positioning of the elements of the edge backlight module  2  during assembly.  
      The reflective surface S 1  in the embodiment is obtained by coating or die-casting a reflective layer on the reflective back plate  25 . The reflective surface S 1 , however, is not limited to this. Further, the shape and size of the wraparound end  253  are relative to the light source module  27  and are not limited to the disclosed shape and size.  
      While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.