Patent Publication Number: US-2015085221-A1

Title: Backlight module and corresponding liquid crystal display

Description:
FIELD OF THE INVENTION 
     The present invention relates to the display field, and more particularly to a backlight module and a corresponding liquid crystal display (LCD) which can reduce weight of the backlight module and lower manufacturing cost of the backlight module. 
     BACKGROUND OF THE INVENTION 
     With the rapid progress and development of display technology, the traditional cathode ray tube (CRT) is phased out gradually due to bad space utilization and huge power consumption and replaced by the compact liquid crystal display (LCD). Because LCD comprises advantages such as high display quality, low power consumption and non-radiation, it is considerably applied to communication, information or consumer electronics, such as laptop, mobile phone, personal digital assistant (PDA), digital video camera, digital camera and liquid crystal television. 
     Please refer to  FIG. 1  and  FIG. 2 .  FIG. 1  is a structural schematic view of a traditional LCD, and  FIG. 2  is a cross-sectional view taken along the line A-A′ in  FIG. 1 . Mostly, the LCD comprises two parts: a backlight module and a display panel  10 . The main function of the backlight module is to provide an uniform surface light source to the display panel  10 . Mainly, the backlight module comprises a light guide plate  11 , a light source (not shown), a plastic housing  12 , a back plate  13  and a front frame  14 . The light guide plate  11  has an incident surface, and the light source is arranged on one side of the incident surface. The plastic housing  12  is used to fix the light guide plate  11  and the light source to the back plate  13 , so that the light from a light emitting surface of the light guide plate  11  can illuminate the display panel  10 . The front frame  14  and the plastic housing  12  commonly clamp the display panel  10  to fix the display panel  10 . 
     As shown in  FIG. 1  and  FIG. 2 , the traditional front frame  14  is generally an integrated into one-piece. The front frame  14  is connected to the plastic housing  12  and the back plate  13  by a plurality of screws  15 , and the cross section thereof is L-shaped. The front frame  14  of this type consumes more raw materials so that the manufacturing cost is higher and the weight of the backlight module is heavier. 
     Therefore, it is necessary to provide a backlight module and a corresponding LCD to solve the problems of traditional technology. 
     SUMMARY OF THE INVENTION 
     The purpose of this invention is to provide a backlight module and LCD. The first frame of the backlight module comprises four straight subframes, so as to provide a simple structure to lower the manufacturing cost of the frame structure and reduce weight of the backlight module in the meantime. It solves the technical problems of higher manufacturing cost for the traditional backlight module and the corresponding LCD and heavier weight for the backlight module. 
     To solve the problems mentioned above, the present invention provides technical solutions, as follows: 
     The present invention relates to a backlight module, comprising: a back plate; a light source mounted on a the back plate and used to provide light to a corresponding display panel; a light guide plate arranged on one side of the light emitting surface of the light source and used to guide the light from the light source; a plastic housing arranged on the back plate and used to fix the light source and the light guide plate onto the back plate; and a front frame comprising four straight subframes which cover the upper surface of the plastic housing and fix the display panel by matching with the plastic housing; wherein the plastic housing has positioning portions thereon to position the front frame; and the front frame is a metallic part or a plastic part corresponding to the shape of the upper surface of the plastic housing. 
     According to the backlight module of the present invention, each of the subframes covers the upper surface of the plastic housing on one side of the backlight module. 
     According to the backlight module of the present invention, the four subframes are integrated into one-piece. 
     According to the backlight module of the present invention, the front frame has through holes, and the front frame is connected to the plastic housing by the through holes. 
     The present invention also relates to a backlight module, comprising: a back plate; a light source mounted on a the back plate and used to provide light to a corresponding display panel; a light guide plate arranged on one side of the light emitting surface of the light source and used to guide the light from the light source; a plastic housing arranged on the back plate and used to fix the light source and the light guide plate to the back plate; and a front frame comprising four straight subframes which cover the upper surface of the plastic housing and fix the display panel by matching with the plastic housing. 
     According to the backlight module of the present invention, the plastic housing has positioning portions thereon to position the front frame. 
     According to the backlight module of the present invention, the front frame is a metallic part or a plastic part corresponding to the shape of the upper surface of the plastic housing. 
     According to the backlight module of the present invention, each of the subframes covers the upper surface of the plastic housing on one side of the backlight module. 
     According to the backlight module of the present invention, the four subframes are integrated into one-piece. 
     According to the backlight module of the present invention, the front frame has through holes, and the front frame is connected to the plastic housing by the through holes. 
     The present invention also relates to a LCD, comprising: a display panel; and a backlight module, comprising: a back plate; a light source mounted on a the back plate and used to provide light to a corresponding display panel; a light guide plate arranged on one side of the light emitting surface of the light source and used to guide the light from the light source; a plastic housing arranged on the back plate and used to fix the light source and the light guide plate to the back plate; and a front frame comprising four straight subframes which cover the upper surface of the plastic housing and fix the display panel by matching with the plastic housing. 
     According to the LCD of the present invention, the plastic housing has positioning portions thereon to position the front frame. 
     The LCD of the present invention, the front frame is a metallic part or a plastic part corresponding to the shape of the upper surface of the plastic housing. 
     According to the LCD of the present invention, each of the subframes covers the upper surface of the plastic housing on one side of the backlight module. 
     According to the LCD of the present invention, the four subframes are integrated into one-piece. 
     According to the LCD of the present invention, the front frame has through holes, and the front frame is connected to the plastic housing by the through holes. 
     Compared to the traditional backlight module and the corresponding LCD, the front frame of the present invention comprises four straight subframes covering the upper surface of the plastic housing and fixing the display panel by matching with the plastic housing, so that it simplifies the structure of the backlight module, which thus lowers manufacturing cost of the backlight module and reduces weight of the backlight module in the meantime. It solves the technical problems of higher manufacturing cost for the traditional backlight module and the corresponding LCD and heavier weight for the backlight module. 
     For the present invention described above will be more apparent, the following specific preferable embodiment with the companying drawings will be elaborated as follows: 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a structural schematic view of a traditional LCD; 
         FIG. 2  is a cross-sectional view taken along the line A-A′ in  FIG. 1 ; 
         FIG. 3  is a structural schematic view of a LCD of the present invention; and 
         FIG. 4  is a cross-sectional view taken along the line B-B′ in  FIG. 3 . 
     
    
    
     Wherein the reference numbers are illustrated as follows: 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                  20. display panel; 
                  23. back plate; 
               
               
                   
                  21. light guide plate; 
                  24. front frame; 
               
               
                   
                  22. plastic housing; 
                 241. subframe; 
               
               
                   
                 221. positioning portion; 
                  25. reflecting layer; 
               
               
                   
                 222. upper-stage portion; 
                  26. optical film; 
               
               
                   
                 223. lower-stage portion. 
               
               
                   
                   
               
            
           
         
       
     
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings. Furthermore, directional terms described by the present invention, such as upper, lower, front, back, left, right, inner, outer, side, longitudinal/vertical, transverse/horizontal, and etc., are only directions by referring to the accompanying drawings. Therefore, the used directional terms are used to describe and understand the present invention, but the present invention is not limited thereto. 
     In the figures, the similar structural units are designated by the same reference numbers. 
     Please refer to  FIG. 3  and  FIG. 4 ,  FIG. 3  is a structural schematic view of a LCD of the present invention, and  FIG. 4  is a cross-sectional view taken along the line B-B′ in  FIG. 3 . The LCD of the present invention comprises a display panel  20  and a backlight module. The backlight module comprises a back plate  23 , a light source (not shown), a light guide plate  21 , a plastic housing  22  and a front frame  24 . As shown in  FIG. 4 , the back plate  23  is arrange under the backlight module; the light source is mounted on the back plate  23  and used to provide light to the corresponding display panel  20 ; the light guide plate  21  is mounted on the back plate  23  as well, and arranged on one side of the light emitting surface of the light source and used to guide the light from the light source; the plastic housing  22  is arranged on the back plate  23  and used to fix the light source and the light guide plate  21  to the back plate  23 ; the front frame  24  comprises four straight subframes  241  which cover the upper surface of the plastic housing  22 ; the upper surface is outside the plastic housing  22  and parallel to the emitting surface of the display panel  20 ; the front frame  24  clamps and fixes the display panel  20  by matching with the plastic housing  22 . 
     What the plastic housing  22  has from top to bottom in turn are: a flanged positioning portion  221  positioning the front frame  24 , a circular upper-stage portion  222  which is relatively outside and a circular lower-stage  223  which is relative inside. The positioning portion  221  can exactly arrange the front frame  24  on the upper-stage portion  222  of the plastic housing  22  to prevent the front frame  24  from shift. The positioning portion  221  can be designed into a variety of structures, such as the flange protruding from the upper-stage portion  222  (i.e. the upper surface) of the plastic housing as shown in  FIG. 4 . It also can be designed into a positioning post for positioning the front frame  24  by matching with the positioning hole of the front frame  24 . 
     The shape of the front frame  24  corresponds to the shape of the plastic housing  22  (for example, rectangular ring shaped), so that the front frame  24  can closely cover the upper-stage portion  222  of the plastic housing  22 . Meanwhile, the front frame  24  has through holes, so that the front frame  24  can closely couple with the upper-stage  222  of the plastic housing  22  by screwing bolts or screws through holes. As shown in  FIG. 4 , the through holes can be arranged on the corresponding positions of the plastic housing  22 . By the through holes of the front frame  24  and the through holes of the plastic housing  22 , the front frame  24  screws to the back plate  23  to fix the front frame  24  and the plastic housing  22  together outsides the back plate  23 . 
     The front frame  24  of the present invention can be a metallic portion or a plastic portion. If the front frame  24  is a metallic portion, it is easier to manufacture the straight metallic portion by pressing or casting for reducing the manufacturing cost of the casting mold of the front frame  24 ; meanwhile the consumption of metallic material can be greatly reduce for saving the manufacturing cost of the front frame  24 . If the front frame  24  is a plastic portion, because its shape correspond to the upper-stage portion  222  of the plastic housing  22 , it need not to manufacture the separate front-frame mode, instead the plastic-frame mold is enough to manufacture the corresponding front frame  24 . 
     The subframes  241  of the front frame  24  of the present invention can be designed into a split combined type, as shown in  FIG. 3 , each of the subframes  241  covers the upper surface (i.e. the upper-stage portion  222 ) of the plastic housing  22  on one side of the backlight module. Thus, the subframe  241  has simple structure and is easy to be mounted. The four straight subframes  241  can be combined to form the front frame  24  with a rectangular ring shape. The four subframes  241  of the present invention can also be integrated into one-piece; the four subframes  241  are combined to form the front frame  24  with a rectangular ring shape, even though the four subframes  241  are molded once by the same mold, which simplifies the manufacture of the front frame  24 . 
     In this embodiment, the light source can be a LED bar, which comprises a circuit board and emitting component (e.g. LED); the circuit board can be for example a printed circuit board (PCB) or flexible printed circuits (FPC), and the emitting component is arranged on the circuit board. The light source has an emitting surface used to illuminate the light guide plate  21 . Preferably, the emitting surface is a plane which can for example be formed on the surface of the emitting component, and preferably the emitting surface is approximately perpendicular to the emitting direction (i.e. the incident direction of the light guide plate  21 ) of the light source. 
     In this embodiment, the light guide plate  21  can be for example a planar structure formed by injection molding, and the material can be for example UV curable resin, poly methyl methacrylate (PMMA) or polycarbonate (PC). The light guide plate  21  comprises an emitting surface, a light reflector and a side-light surface. The emitting surface is positioned in front of the light guide plate  21  and used to pass the light from the light guide  21  to the display panel  20 ; the light reflector is positioned on the base surface of the light guide plate  21  and opposite to the emitting surface. Each of the side-light surfaces of the light guide plate  21  is formed on one side of the light guide plate  21  or on opposite sides; the side-light surface corresponds to the emitting surface of the light source and used to pass the light from the light source into the light guide plate  21 . The side-light surface is approximately perpendicular to the emitting surface. 
     The back plate  23  of this embodiment is formed by opaque materials such as plastic, metal or the combination of the above-mentioned materials. 
     Further, a reflecting layer can be arranged on the light reflector of the light guide plate  21 ; the reflecting layer can be for example a reflecting film or a reflecting coating with high-reflectivity materials for reflecting the light. These high-reflectivity materials can be for example silver, aluminum, gold, chromium, copper, indium, iridium, nickel, platinum, rhenium, rhodium, tin, tantalum, tungsten, manganese, alloy of any of the above combination, and white reflecting paint with yellowing resistance and heat resistance or any combination of the above-mentioned materials. It is worth notice that the reflecting surface of the light guide plate  21  also can be coated by the high-reflectivity materials to reflect the incident light, so that it can further replace and neglect the reflecting layer  25 . 
     Meanwhile, an optical film  26 can be arranged on the emitting surface of the light guide plate  21 ; the optical film  26  can be for example a diffusion sheet, a prism sheet, a turning prism sheet, a brightness enhancement file (BEF), a dual brightness enhancement film (DBEF), a diffused reflective polarizer film (DRPF) or a combination of any above-mentioned sheet for improving the emitting performance of the light guide plate  21 . 
     When installing the LCD of the present invention, the light source and the light guide late are firstly arranged on the corresponding positions of the back plate  23  (arranging the reflecting layer  25  and the optical film  26  simultaneously when arranging the light guide plate  21 ); then a plastic housing  22  is arranged on the back plate  23 , and the light source and the light guide plate  21  is fixed on the back plate  23  by the plastic housing  22 ; subsequently, the display panel  20  is arranged on the upper-stage portion  222  of the plastic housing  22 ; finally the front frame  24  (e.g. four straight subframes  241 ) is arrange on the upper-stage portion  222  of the plastic housing  22  by screwing, so that the front frame  24  is fixed firmly on the upper-stage portion  222  of the plastic housing  22 , in the meanwhile, a space is formed by the front frame  24  and lower-stage portion  223  of the plastic housing  22  for clamping the display panel  20 ; the height of the clamping space is roughly equal to or smaller than the thickness of the display panel  20 ; the arrangement of the LCD is completed basically in this way. 
     The front frame of the backlight module and the LCD of the present invention comprises four straight subframes, which greatly simplifies the backlight module, especially the structure of the front frame, so that it lowers the manufacturing cost of the backlight module and reduce weight of the backlight module. Therefore, it solves the technical problems of higher manufacturing cost and heavier weight of the traditional backlight module and the corresponding LCD. 
     The present invention has been described with a preferred embodiment thereof and it is understood that many changes and modifications to the described embodiment can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.