Patent Publication Number: US-2005122444-A1

Title: Reflector of backlight assembly for liquid crystal display device

Description:
DESCRIPTION OF THE INVENTION  
      1. Field of the Invention  
      This invention relates in general to a backlight assembly for a liquid crystal display (“LCD”) device and, more particularly, to a reflector of a backlight assembly for a LCD device.  
      2. Background of the Invention  
      LCD devices may include reflection-type, transmission-type and reflective transmission-type displays. In a reflection-type LCD device, an image is displayed by reflecting ambient light or sunlight incident on the LCD device. In a transmission-type LCD device, an image is displayed by the light emitted from a light source such as a lamp provided to the LCD device. In a reflective transmission-type LCD device, which is half reflection type and half transmission type, uses both an external light source such as ambient light or sunlight, and an internal light source such as a lamp. The transmission-type or reflective transmission-type LCD devices may generally include a backlight assembly for providing light to light a LCD panel.  
       FIG. 1  shows a cross-sectional view of a backlight assembly  10  of a conventional transmission-type or reflective transmission-type LCD device. Referring to  FIG. 1 , backlight assembly  10  includes a lamp  12 , a reflector  14 , and a diffusion plate  16 . Light emitted from lamp  12  is incident on reflector  14 , reflected by reflector  14 , and then transmits through diffusion plate  16 . It is desirable that the reflected light transmits in a direction normal to the surface of diffusion plate  16 , resulting in a maximum flux of light provided. However, reflector  14  usually includes a base portion  18  and sidewall portions  20  extending from base portion  18  at an angle θ. In such a “single-angle” structure of reflector  14 , light reflected from sidewall portions  20  may form with respect to the normal direction of diffusion plate  16  an angle α large enough to deteriorate the total flux of light provided by backlight assembly  10 .  
     SUMMARY OF THE INVENTION  
      Accordingly, the present invention is directed to a backlight assembly that obviates one or more of the problems due to limitations and disadvantages of the related art.  
      To achieve these and other advantages, and in accordance with the purpose of the invention as embodied and broadly described, there is provided a liquid crystal display device that comprises a light-emitting source emitting light, and a reflector further comprising a base and a plurality of sidewalls extending from the base, wherein each of the sidewalls further comprises a multi-angle surface, in conjunction with the base, reflecting the emitted light toward a diffusion plate diffusing the reflected light.  
      In one aspect, the multi-angle surface is an infinite-angle surface.  
      In another aspect, the light emitting source, the reflector and the diffusion plate form a backlight assembly for the liquid crystal display device.  
      Also in accordance with the present invention, there is provided a liquid crystal display device that comprises a light-emitting source emitting light, a multi-angle reflector for reflecting the emitted light, and a diffusion plate for diffusing the reflected light.  
      In one aspect, the reflector further comprises a base formed substantially parallel to the light emitting source, a plurality of sidewalls extending from the base, and each of the sidewalls further comprising a multi-angle surface, in conjunction with the base, reflecting the emitted light toward the diffusion plate.  
      In another aspect, the multi-angle surface further comprises an infinite-angle surface and curved surface.  
      Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.  
      It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.  
      The accompanying drawing, which is incorporated in and constitutes a part of this specification, illustrates several embodiments of the invention and together with the description, serves to explain the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a cross-sectional view of a conventional backlight assembly;  
       FIG. 2  is a cross-sectional view of a liquid crystal display device in accordance with one embodiment of the present invention; and  
       FIGS. 3A and 3B  are cross-sectional views of a backlight assembly in accordance with one embodiment of the present invention.  
    
    
     DESCRIPTION OF THE EMBODIMENTS  
      Reference will now be made in detail to the present embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
       FIG. 2  is a cross-sectional view of a liquid crystal display (“LCD”) device  30  in accordance with one embodiment of the present invention. LCD device  30  is not necessarily drawn to scale, in which the dimensions of various components may be arbitrarily increased or reduced. Referring to  FIG. 2 , LCD device  30  includes a LCD panel  32  for displaying video images, and a backlight assembly  34  for lighting LCD panel  32 . Backlight assembly  34  includes a lamp  36 , a reflector  38 , and a diffusion plate  40 . Lamp  36  functions to serve as a light-emitting source. In one embodiment according to the invention, lamp  36  includes a cold-cathode fluorescent lamp attached within reflector  38 . Reflector  38  reflects the light emitted from lamp  36  toward diffusion plate  40 , which in turn diffuses the reflected light to LCD panel  32 . In a further embodiment according to the invention, diffusion plate  40  is made of acrylic resin.  
      Reflector  38  includes a base portion  42  and sidewall portions  44  extending from base portion  42 . Each sidewall portion  44  includes a multi-angle surface (not numbered) such that the light emitted from lamp  36  is reflected by the multi-angle surface and base portion  42  toward diffusion plate  40 . The multi-angle surfaces help alleviate the problem of a large angle α in a single-angle structure as discussed with respect to  FIG. 1 .  
      Backlight assembly  34  generally includes a frame  46  for accommodating lamp  36  and reflector  38 . Frame  46  includes a base portion  48  on which reflector  38  is mounted, and sidewall portions  50  extending from base portion  48  to support diffusion plate  40 . Backlight assembly  34  may also include optical sheets (not numbered) formed on diffusion plate  40  in lighting LCD panel  32 . The optical sheets may include a prism sheet  52  formed on diffusion plate  40 , and a diffusion sheet  54  formed on prism sheet  50 .  
      In the example of  FIG. 2 , reflector  38  includes a two-angle sidewall surface. In other embodiments, however, a reflector may include a sidewall surface having more than two angles, as shown in  FIGS. 3A and 3B . Referring to  FIG. 3A , a reflector  60  includes a base portion  62  and a three-angle sidewall surface  64 . Referring to  FIG. 3B , a reflector  70  includes a base portion  72  and an infinite-angle sidewall surface  72 . That is, reflector  70  includes a curved sidewall surface.  
      Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.