Abstract:
Backlight assembly includes a plurality of light guide plates, a plurality of light modules, and a plurality of driving units separately in control of corresponding light modules which are configured at the incident sides of the LGPs. Each light module faces two adjacent LGPs such that the driving unit drives the light module to provide light for two adjacent LGPs at the same time. As local dimming function is switched, besides the power-saving and the high contrast, the local edge effect due to the joint of the LGPs can be reduced.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a backlight assembly, and more particularly, to a combinative edge lighting backlight assembly with misaligning light sources and light guide plates. 
     2. Description of the Prior Art 
     In a traditional edge lighting backlight assembly, light enters from the side. Such structure makes it difficult to maintain light uniformity as the size of the backlight assembly increases. Combination of a number of smaller-sized light guide plates to form a large light guide plate is therefore carried out, each smaller-sized light guide plate receiving light from a stand-along light module, such that a large size edge lighting backlight assembly can still have its luminance and uniformity above a standard. 
     Compared to the single large-sized light guide plate, light emitted from every block of the combination of all the small-sized light guide plates may differ from one another, because of the difference of physical property of each light guide plate and the light module, and the way the light guide plates assemble with the light modules. On the other hand, the joint between two light guide plates shows discontinuity. The edge fault of the light guide plate is a common problem in the combinative backlight assembly because the backlight assembly is configured with a light source corresponding to a light guide plate. 
     Additionally, when a direct-type backlight assembly uses light emitting diodes (LEDs) as the light source, turning on part of the LEDs can save power for the backlight assembly, when maximum Luminance is unnecessary. The backlight assembly can also have greater contrast by turning on only part of the LEDs. Such technique is called local dimming. Please refer to  FIG. 1 .  FIG. 1  is a diagram of display effect of a display  10  when a combinative edge lighting backlight assembly performs its local dimming function according to the prior art. When applying local dimming function on an edge lighting backlight assembly, however, the edge between a block with light turning on and a block with light turning off can be much more obvious since the light guide plate and the light source are configured one by one Although the direct-type backlight assembly has better performance with local dimming, the thickness of the direct-type backlight assembly is greater than that of the edge lighting backlight assembly. 
     SUMMARY OF THE INVENTION 
     The present invention provides a backlight assembly, which includes a back plate, a first light guide plate, a second light guide plate, a light module, and a driving unit. The first light guide plate is configured on the back plate and has a first incident side. The second light guide plate is arranged adjacent to the first light guide plate along a first direction, configured on the back plate, and has a second incident side. The light module is configured for facing both the first incident side and the second incident side. The driving unit drives the light module to provide the same batch of incident light for the first incident side and the second incident side at the same time. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of display effect of a display when a combinative edge lighting backlight assembly performs its local dimming function according to the prior art. 
         FIG. 2  is a perspective explosive diagram of a first embodiment of a backlight assembly according to the present invention. 
         FIG. 3  is a plane diagram of the first embodiment of the backlight assembly according to the present invention. 
         FIG. 4  is a perspective diagram of a second embodiment of a light guide plate according to the present invention. 
         FIG. 5  is a sectional view of the first embodiment of the light guide plate according to the present invention. 
         FIG. 6  is a sectional view of the first embodiment of the backlight assembly according to the present invention. 
         FIG. 7  is a perspective explosive diagram of a third embodiment of the backlight assembly according to the present invention. 
         FIG. 8  is a diagram of display effect of the display when the assembly performs its local dimming function according to the first embodiment of the present invention. 
         FIG. 9  is a perspective explosive diagram of a fourth embodiment of the backlight assembly according to the present invention. 
         FIG. 10  is a plane diagram of a fifth embodiment of the backlight assembly according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 2 .  FIG. 2  is a perspective explosive diagram of a first embodiment of a backlight assembly  20  according to the present invention. The backlight assembly  20  includes a back plate  21 , a light module group  40 , a light guide plate group  30  (LGP group), a plurality of driving units  51 ˜ 56  (shown in  FIG. 3 ), and an optical film group (or an optical plate group)  24 . The light module group  40 , the light guide plate group  30 , and the optical film group  24  are sequentially configured on the back plate  21 . One or more reflectors  22 ,  23  are further configured between the back plate  21  and the light guide plate group  30 . The reflectors  22 ,  23  are configured facing light guide plates  31 ,  32  respectively. However, a single long reflector or one reflector  22 ′ (shown in a fourth embodiment in  FIG. 9 ) can also correspond to the plurality of light guide plates  31 ,  32 . The back plate  21  can be housing that fixes or surrounds other components, and can be a metal cover made of Aluminum or Aluminum alloy material. The element function and the configuration way of the reflectors  22 ,  23  and the optical film group  24  can be known by person of ordinary skill in the art and should be omitted for brevity purpose. 
     In the lighting backlight assembly  20  including a small-sized light guide plate group  30  and the light module group  40 , all light modules  41 ˜ 46  of the light module group  40  are configured misaligning with corresponding two of the light guide plates  31 ˜ 34  of the light guide plate group  30  respectively.  FIG. 3  shows that each of the light modules  41 ˜ 46  is controlled by a corresponding one of driving units  51 ˜ 56 . In other words, each of the light guide plates  31 ˜ 34  can receive light from the corresponding two of the light modules  41 ˜ 46 . For example, the light guide plate  31  can receive light from the light modules  41 ,  42 , and the light guide plate  32  can receive light from the light modules  42 ,  43 . Each of the light guide plates  31 ˜ 34  can be formed as plane surface wedge-shaped plate by injection molding manner, made of Polymethyl Methacrylate (PMMA) material or other high transmittance material. 
     Please refer to  FIG. 3 .  FIG. 3  is a plane diagram of the first embodiment of the backlight assembly according to the present invention. A large light guide plate can be decomposed to many small light guide plates to manufacture large-size display panel. For example, a light guide plate for a 46-inches liquid-crystal display can be decomposed to 16×8 (128) pieces small light guide plates. In this embodiment, the light guide plates  31 ˜ 34  are arranged in a matrix manner, for descriptive purpose, the light guide plates  31 ,  32  and the light guide plates  33 ,  34  are arranged along a first direction X respectively, while the light guide plates  31 ,  33  and the light guide plates  32 ,  34  are arranged along a second direction Y respectively. The range of diagonal length of each of the light guide plates  31 ˜ 34  is between 3.4 inches and 10 inches. Although each of the light guide plates  31 ˜ 34  is identical in shape and size presenting this embodiment, they can also have different shape and size in actual application, as long as they form a big light guide plate through combinative way. 
     In the embodiment in  FIG. 3 , the light guide plates  31 ˜ 34  have plane sides respectively. For example, the light guide plate  31  has a side  316  and the light guide plate  32  has a side  326  along the second direction Y. The light guide plates  31  is adjacent to the light guide plate  32  by the sides  316 ,  326  contacting or matching with each other such that the light guide plates  31 ,  32  can be arranged along the first direction X. Additionally, the light guide plate  31  can be adjacent to the light guide plate  32  in another way for increasing light transmissible effect between the light guide plate  31  and the light guide plate  32 . Please refer to  FIG. 4 .  FIG. 4  is a perspective diagram of a second embodiment of the light guide plates  31 ′,  32 ′ according to the present invention. The light guide plates  31 ′,  32 ′ both comprise the saw-toothed sides  316 ′,  326 ′ along the second direction Y, and the saw-toothed sides  316 ′,  326 ′ match with each other so that the light guide plates  31 ′,  32 ′ can be arranged along the first direction X. Likewise, the contacting and matching relationship of two light guide plates are adapted to all light guide plates in the present invention. 
     Please refer to  FIG. 5 ,  FIG. 6 , and  FIG. 7 .  FIG. 5  is a sectional view of the first embodiment of the light guide plate  31  according to the present invention.  FIG. 6  is a sectional view of the first embodiment of the backlight assembly  20  according to the present invention. The light guide plate  31  includes an emitting plane  311 , a bottom  312 , a tail section  313 , an indentation  314 , and an incident side  315 . The section view of the light guide plate  31  shows a wedge structure in this embodiment. Also in this embodiment, the height H 2  of the incident side  315  ranges between 0.24 inches and 0.79 inches, the height (or depth) H 5  between the indentation  314  and the emitting plane  311  ranges between 0.29 inches and 0.55 inches, and the thickness (including H 3  and H 4 ) of the tail section  313  ranges between 0.25 inches and 0.47 inches. The tail section  313  of the light guide plate  31  is a gradually-narrowing structure. The thickness H 4  corresponding to the incident side  315  is larger than the thickness of the rest of the tail section  313 , and the thickness H 3  corresponding to the incident side  315  is smaller than the thickness of the rest of the tail section  313 .  FIG. 7  is a perspective explosive diagram of a third embodiment of the backlight assembly according to the present invention. The light guide plate  31  can further include a plurality of micro-structures  317  on the incident side  315 . The micro-structures  317  can be a plurality of tetrahedrons arranged in a matrix manner or a plurality of rhombohedrons (or prisms) extending perpendicular to the back plate  21  for increasing the luminous flux of the light module in the incident side  315 . It is not limited in the present invention. 
     Please refer to  FIG. 6 . The tail section  313  of the light guide plate  33  is configured on the indentation  314  of the light guide plate  31 , while another tail section of another light guide plate (not shown in Figure) is configured on the indentation  334  of the light guide plate  33 . A gap  442  is formed amid the incident side  315  of the light guide plate  31 , the bottom  332  of the light guide plate  33  (or the reflector  24  of the bottom  332 ), and the back plate  21 . The light module  42  facing the light guide plate  31  is contained in the gap  442  for providing the incident light for the incident side  315  of the light guide plate  31 . 
     Please also refer to  FIG. 3 . The first embodiment of the present invention shows that a group of light modules  41 ˜ 43  are arranged along the first direction X, and another group of light modules  44 ˜ 46  are also arranged along the first direction X. The light modules  41 ˜ 43  are parallel with the light modules  44 ˜ 46 . Each of the light modules  44 ˜ 46  faces the incident sides of two light guide plates respectively. For example, the light module  42  is configured to face the incident sides of the light guide plates  31 ,  32 . In this embodiment, the light modules  41 ˜ 46  are drove (or controlled) individually by the driving units  51 ˜ 56 . The light module  42  can be a light-emitting diode device including a plurality of light-emitting diodes  421 . The driving units  52  can drive individually all light-emitting diodes  421  of the light module  42  so as to provide the same batch of incident light for the incident sides of the light guide plates  31 ,  32 . 
     In this embodiment, each of the light modules  41 ˜ 46  is configured misaligning with two of the light guide plates  31 ˜ 34 . It means that the left half and the right half of one light module equally face half of incident sides of two adjacent light guide plates. For example, the left half of the light module  42  faces the right half of the light guide plate  31 , the right half of the light module  42  faces the left half of the light guide plate  32 . The length of the light module  42  and incident sides of the light guide plate  31  and the light guide plate  32  are substantially the same. In other embodiment of the present invention, however, the light module can also face the two incident sides of adjacent light guide plates with other proportion. For example, one third of the left light module  42  faces the right half of the light guide plate  31 , and two third of the right light module  42  faces the left half of the light guide plate  32 . Additionally, the length of the light modules  41 ′˜ 44 ′ can also differ from the length of the light guide plates  31 ˜ 33 , as shown in a fifth embodiment in  FIG. 10 . For example, the light modules  41 ′˜ 44 ′ and the light guide plates  31 ˜ 33  are configured respectively along the first direction X, three light guide plates  31 ˜ 33  are collocated with four light modules  41 ′˜ 44 ′. While the total length of the three light guide plates  31 ˜ 33  is the same as the total length of the four light modules  41 ′˜ 44 ′ along the first direction X, the single length of each incident side of the light guide plates  31 ˜ 33  differs from the length of each light module. In this embodiment, four light modules  41 ′˜ 44 ′ are configured misaligning with three light guide plates  31 ˜ 33 , in which the light modules  42 ′ is configured facing the light guide plates  31 ,  32 , the light modules  43 ′ is configured facing the light guide plates  32 ,  33 . In other words, each of the light guide plates  31 ˜ 33  receives light from two adjacent light modules  41 ′˜ 44 ′ respectively, which means that the light guide plate  31  faces the light modules  41 ′˜ 42 ′, the light guide plate  32  faces the light modules  42 ′˜ 43 ′, and the light guide plate  33  faces the light modules  43 ′˜ 44 ′. 
     Please refer to  FIG. 3 . Additionally, since each light guide plate  31 ˜ 34  receives light from two adjacent light modules  41 ˜ 46  at the same time, light from the two adjacent light modules  41 ˜ 46  can be mixed after entering one of the light guide plates  31 ˜ 34 , further reducing the difference of light from each light module  41 ˜ 46 . Luminance from the incident sides of the light guide plates  31 ˜ 34  is much more plane. The shape of the light guide plates  31 ˜ 34  can be rectangular, square, rectangle-like, or square-like, wherein the rectangle-like or square-like light guide plates are the rectangular or square light guide plates with concave or convex optical structures at the edges thereof. 
     Please refer to  FIG. 8 .  FIG. 8  is a diagram of display effect of the display when the assembly performs its local dimming function according to the first embodiment of the present invention. Different from the display effect in  FIG. 1 , when the local dimming function is performed in the display  100 , the light modules  41 ˜ 43 , which misalign with the light guide plate  31  and the light guide plate  32  under the display  100 , are driven by each of the driving units  51 ˜ 53  respectively, each one either turning on or turning off. For example, the driving unit  51  turns on the light module  41  to emit light, and the driving units  52 ,  53  turn off the light modules  42 ,  43 . The gradual display effect is shown in  FIG. 8 . In  FIG. 8 , a darker block  112 , a middle block  113 , and a lighter block  111  are shown. The adjacent edge between the light guide plate  31  and the light guide plate  32  becomes vague when local dimming function is performed. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.