Abstract:
The invention discloses a light guide plate structure. The light guide plate structure includes a light-receiving surface, a light-emitting surface and a light-reflecting surface. The light-receiving surface receives emitting light from at least a light source, and the light propagating in the light guide plate exits through the light-emitting surface. The light-reflecting surface is opposite to the light-emitting surface for guiding the light that passes through the light-receiving surface to the light-emitting surface. The light-emitting surface and/or the light-reflecting surface include at least a composite structure. The composite structure includes a primary structure and a secondary structure where the secondary structure is disposed to a side of the primary structure.

Description:
BACKGROUND OF THE INVENTION  
       [0001]    (a) Field of the Invention 
         [0002]    The present invention relates to a light guide plate structure, and more particularly, to a light guide plate structure having excellent light guiding efficiency. 
         [0003]    (b) Description of the Related Art 
         [0004]    Currently, most of the light guide plates are processed by etching method and the shape of its surface structure can have a variety of geometrical shapes, such as: circle, rectangle, diamond shape, or the like. 
         [0005]    Generally, when producing a light guide plate G as shown in  FIG. 1A , an indent structure Tc is usually etched into the stamper T. Then, the light guide plate G is formed on the stamper T by the injection molding method. 
         [0006]    However, During the injection molding process, it is common that the surface structure Gc of the light guide plate is poorly formed due to air enclosure between the indenting structure Tc and the injected material. Thus, the geometrical shapes having larger indenting depth (such as cone shape or sphere) shown in  FIG. 1A  cannot be achieved. Hence, when light enters the light guide plate G with poorly formed surface structure Gc from the left-hand side as shown in  FIG. 1B , the light diffusing efficiency becomes low due to the poorly formed surface structure Gc. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In light of the above-mentioned problem, one object of the invention is to provide a light guide plate structure to have the light radiated from light source(s) more evenly so as to increase the light guiding efficiency. 
         [0008]    One embodiment of the invention provides a light guide plate. The light guide plate includes a light-receiving surface, a light-emitting surface, and a light-reflecting surface. The light-receiving surface is for receiving light from at least one light source. The light-emitting surface is for the light that enters the light guide plate to exit through the light-emitting surface. The light-reflecting surface is opposite to the light-emitting surface for reflecting the light that enters the light guide plate via the light-receiving surface to the light-emitting surface. The light-emitting surface or the light-reflecting surface, or both include at least one composite structure. The composite structure includes at least a primary structure and at least a secondary structure, and the secondary structure is disposed to a side of the primary structure. The primary structure and the secondary structure are formed toward the opposite direction with reference to a plane of the light-emitting surface or a plane of the light-reflecting surface, respectively. 
         [0009]    Another embodiment of the invention provides a light guide plate. The light guide plate is for receiving and guiding the light generated from at least one light source to exit therethrough. The light guide plate includes a plurality of surfaces wherein at least a first surface includes a plurality of composite structures. The composite structure includes at least a primary structure and at least a secondary structure and the secondary structure is placed around the primary structure. The primary structure and the secondary structure are formed toward the opposite direction with reference to a plane of the first surface. 
         [0010]    Another embodiment of the invention provides a backlight module. The backlight module includes at least one light source and at least one light guide plate. The light guide plate includes a light-receiving surface, a light-emitting surface, and a light-reflecting surface. The light-receiving surface is adjacent to the light source for receiving the light from the light source. The light-emitting surface is for the light that enters the light guide plate to exit the light guide plate. The light-reflecting surface is opposite to the light-emitting surface for reflecting the light that enters the light guide plate via the light-receiving surface to the light-emitting surface. The light-emitting surface or the light-reflecting surface, or both include a plurality of composite structures. Each of the composite structures includes at least a primary structure and at least a secondary structure, and the secondary structure is disposed around the primary structure. The primary structure and the secondary structure are formed toward the opposite direction with reference to a plane of the light-emitting surface or a plane of the light-reflecting surface, respectively. 
         [0011]    The backlight module and the light guide plate thereof according to the embodiments of the invention utilize the combination of the protruding and the indenting curved surfaces of the composite structures to increase the overall surface roughness of the light-emitting surface and/or the light-reflecting surface for solving the problem of uneven light diffusion that may occur when the light enters the light guide plate. Increasing the light diffusing efficiency can be achieved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0012]      FIG. 1A  shows a schematic diagram illustrating a light guide plate according to the prior art; 
           [0013]      FIG. 1B  shows a schematic diagram illustrating the light propagation of the light guide plate according to the prior art; 
           [0014]      FIG. 2  shows a schematic diagram illustrating the backlight module according to one embodiment of the invention; 
           [0015]      FIG. 3A  shows a schematic diagram illustrating the top perspective view of the light guide plate according to one embodiment of the invention; 
           [0016]      FIG. 3B  shows a schematic diagram illustrating the enlarged drawing of the composite structure according to one embodiment of the invention; 
           [0017]      FIG. 4  shows a schematic diagram illustrating the light propagation of the light guide plate according to one embodiment of the invention; 
           [0018]      FIG. 5  shows a schematic diagram illustrating the backlight module according to one embodiment of the invention; 
           [0019]      FIG. 6  shows a schematic diagram illustrating the light propagation of the light guide plate according to one embodiment of the invention; and 
           [0020]      FIGS. 7A-9B  show schematic diagrams illustrating the composite structures according to one embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    The following descriptions together with the relevant drawings illustrate the embodiments of the invention in detail so that those who are skilled in the art can implement the invention. It should be noted that, although there are differences in the embodiments of the invention, the structures or the features related to any embodiments of the invention as described in the disclosure can be applied in other embodiments of the invention without deviating from the scope of the invention and should not be construed as any limitation on the implementation of the invention. Besides, it should be recognized that the arrangement and the position of each individual part in the embodiments of the invention, that are explicitly described, can be altered as long as the arrangement and the position are within the scope of the invention. That is, the scope of the present invention is defined by the accompanying claims. 
         [0022]      FIG. 2  shows a schematic diagram illustrating the backlight module according to one embodiment of the invention. The backlight module  20  includes a light source  21 , a light guide plate  22 , and a light conducting element  23 . 
         [0023]    The light source  21  can be a point light source, such as light emitting diodes (LED), various other existing light sources, or various light sources to be developed in the future. 
         [0024]    The light guide plate  22  is for receiving and guiding the light generated from at least one light source  21  (such as a point light source) to exit the light guide plate. The light guide plate  22  further includes a light-receiving surface  22   a,  a light-emitting surface  22   b,  and a light-reflecting surface  22   c.  The light-receiving surface  22   a  is adjacent to the light source  21  for receiving the light from the light source  21 . The light-emitting surface  22   b  and the light-receiving surface  22   a  form an included angle. The light-emitting surface  22   b  is for the light that enters the light guide plate  22  via the light-receiving surface  22   a  to exit the light guide plate  22 . The light-reflecting surface  22   c  opposite to the light-emitting surface  22   b  is for reflecting the light that enters the light guide plate  22  via the light-receiving surface  22   a  to the light-emitting surface  22   b.  The light-reflecting surface  22   c  includes at least one composite structure  22   c ′ (a plurality of composite structures are shown in the figure). Each of the composite structures includes at least a primary structure  22   c   1  and at least a secondary structure  22   c   2 , and the secondary structure  22   c   2  is disposed to (or around) the side, the edge, or the periphery of the primary structure  22   c   1 . The primary structure  22   c   1  and the secondary structure  22   c   2  can be formed toward the opposite direction with reference to a plane of the light-emitting surface  22   b  or a plane of the light-reflecting surface  22   c,  respectively. According to one embodiment of the invention, the primary structure  22   c   1  of the composite structure  22   c ′ of the light guide plate  22  can be of half-cone shape or hemisphere shape protruding a plane of the light-reflecting surface  22   c.  For example, the secondary structure  22   c   2  can be an “O” shaped groove indenting a plane of the light-reflecting surface  22   c.    
         [0025]    The light conducting element  23  can be a prism sheet, a diffusing sheet, or any combination thereof, disposed between the light guide plate  22  and a display panel (not shown in the figure). 
         [0026]      FIG. 3A  shows a schematic diagram illustrating the top perspective view of the light guide plate  22  along the direction of the arrow shown in  FIG. 2 . As the figure illustrates the light guide plate  22  via the perspective drawing, a plurality of composite structures  22   c ′ arranged in a pre-determined pattern on the light-reflecting surface  22   c  can be observed. It should be noted that the arrangement of the composite structures  22   c ′ is only shown as an example. The pattern and the density of the arrangement can be design by the user at will.  FIG. 3B  shows a schematic diagram illustrating the simulated enlarged drawing of the composite structure  22   c ′. The embodiments of the primary structure  22   c   1  and the secondary structure  22   c   2  according to the invention can be seen in the figure. According to one embodiment of the invention, the secondary structure  22   c   2  is disposed to a side of the primary structure  22   c   1  in a continuous surrounding fashion and the primary structure  22   c   1  and the secondary structure  22   c   2  mutually contact with each other. In another embodiment of the invention, the disposition of the primary/secondary structures  22   c   1 ,  22   c   2  can contact with each other by remaining a gap between them or partially contacting with each other. The secondary structure  22   c   2  according one other embodiment of the invention can also be disposed to a side of the primary structure in an intermittently surrounding fashion. 
         [0027]    Referring to the  FIGS. 1A ,  1 B, and  4  at the same time, the following describe the backlight module and the light guide plate thereof according to the embodiments of the invention to solve the problems in the prior art and to increase light diffusing efficiency. 
         [0028]      FIG. 4  shows a schematic diagram illustrating the light trace of the light guide plate according to one embodiment of the invention. When the light from the light source  21  enters the light guide plate  22  from the left-hand side of the figure, one portion of the light is diffused upwardly out of the light guide plate  22  via the secondary structure  22   c   2  while the remaining portion of the light is diffused upwardly out of the light guide plate  22  via the primary structure  22   c   1 . The primary/secondary structures functioning together can increase the light diffusing effect. Such diffusing efficiency is far higher than the light diffusing efficiency in the prior art shown in  FIG. 1B  (only a portion of the light received shown in  FIG. 1B  is diffused upwardly out of the light guide plate G via the surface structure Gc while the remaining portion is scattered toward the right-hand side of the figure and is not diffused out of the light guide plate G). As can be seen, the light guide plate  22  according to the embodiment of the invention utilizes the secondary structure  22   c   2  disposed to a side of the original primary structure  22   c   1 , protruding or indented correspondingly, to increase the overall surface roughness of the light-reflecting surface  22   c  of the light guide plate  22 . The light diffusing efficiency can be increased by reflecting the light simultaneously via the primary/secondary structures  22   c   1 ,  22   c   2  to achieve the better light diffusing effect than that of the prior art. Certainly, if the above mentioned injection molding problem in the prior art as shown in  FIG. 1A  causes the depth of the primary structure  22   c   1  to become shallow, the secondary structure  22   c   2  according to the embodiment of the invention not only compensates the light diffusion loss caused by the poorly formed primary structure  22   c   1  but also solves the technical problems in the prior art. 
         [0029]      FIG. 5  shows a schematic diagram illustrating the backlight module according to another embodiment of the invention. The architecture of the backlight module of this embodiment is similar to that of the backlight module shown in  FIG. 2 . The details of its structure will not be described. However, the technical differences will be given in the following descriptions. The primary structure  22   c   1  of the composite structure  22   c ′ according to this embodiment shown in  FIG. 5  is a half-cone or a hemisphere indenting into a plane of the light-reflecting surface  22   c.  In addition, the secondary structure  22   c   2 , for example, is an O shaped bump disposed around the primary structure  22   c   1  and protruding a plane of the light-reflecting surface  22   c.    FIG. 6  shows a schematic diagram illustrating the light propagation of the light guide plate according to this embodiment. As shown in the figure, the light diffusing efficiency better than that in the prior art can be achieved by the primary/secondary structures  22   c   1 ,  22   c   2  functioning together. 
         [0030]    Besides, the composite structure of the light guide plate according to the invention can be formed by alternately disposing a plurality of primary structures and a plurality of secondary structures. The primary structure and the secondary structure can also be alternately disposed to be indenting or protruding structures. Certainly, the composite structure can also be formed by alternately disposing one primary structure and a plurality of secondary structures. Hence, the variety and the complexity of the structure of the light-reflecting surface  22   c  can be increased to further increase the light diffusing efficiency. 
         [0031]    The light guide plate according to another embodiment of the invention is shown in  FIG. 7A . The composite structure  22   c ′ of the light guide plate  22  according to this embodiment is formed by the union of four primary structures  22   c   1  indenting into a plane of the light guide plate  22  and four secondary structures  22   c   2  protruding a plane of the light guide plate  22 . The light guide plate according to one other embodiment of the invention is shown in  FIG. 7B . The composite structure  22   c ′ of the light guide plate  22  according to this embodiment is formed by the union of four primary structures  22   c   1  protruding a plane of the light guide plate  22  and four secondary structures  22   c   2  indenting into a plane of the light guide plate  22 .  FIGS. 8A ,  8 B show the composite structures of the light guide plate according to one other embodiment of the invention. In these two figures, the indenting or protruding structures of the primary structure and the secondary structure are disposed in reverse. 
         [0032]    The primary structure  22   c   1  and the secondary structure  22   c   2  can be belt-like (or stripe-like) structures according to one embodiment of the invention shown in  FIG. 9A . The solid drawing of the simulated structures is shown in  FIG. 9B . 
         [0033]    It should be noted that, according to the embodiments of the invention, the size and the height of the primary structure of the composite structure to those of the secondary structure of the composite structure are of a pre-determined ratio. For example, the height ratio of the primary structure to that of the secondary structure can be 5:1 or 5:2. For instance, when the height of the primary structure is 30 μm, the height of the secondary structure is designed to be 6˜12 μm. Or, the diameter of the primary structure can be 20˜160 μm while the diameter of the secondary structure is 10˜40 ˜m. Certainly, the data shown in the above mentioned pre-determined values are only examples used to describe the embodiments of the invention and should not be construed as any limitation on the scope of implementing the invention. Besides, the numbers of the primary/secondary structures are also not limited to the above-mentioned examples. The primary or the secondary structures can be of various forms. For example, the surface of the primary structure and/or the secondary structure is selected from the group consisting of the following: a curved surface, a rough surface, a smooth surface, or any combination thereof. Please note that the primary structure and the secondary structure can be disposed on the light-emitting surface or the light-reflecting surface of the light guide plate, or disposed on both of the light-emitting surface and the light-reflecting surface, simultaneously. The shapes of the primary/secondary structures can be a stripe-like shape, an O-shaped groove, an O-shaped bump, a cone, half cone, a hemisphere, a diamond shape, a rectangular shape, an irregular structure, or the like, or any combination thereof. 
         [0034]    In conclusion, the backlight module and the light guide plate thereof according to the embodiments of the invention utilize the combination of the protruding and the indenting curved surfaces of the composite structures to increase the overall surface roughness of the light-emitting surface and/or the light-reflecting surface for solving the problem of uneven light diffusion that may occur when the light enters the light guide plate. According to the present invention, increasing light diffusing efficiency can be achieved.