Patent Publication Number: US-2013234921-A1

Title: Reflection-Light Backlight Module and LCD Device

Description:
TECHNICAL FIELD 
     The invention relates to the field of liquid crystal displays (LCDs), and more particularly to a reflection-light backlight module and an LCD device. 
     BACKGROUND 
     Because of the advantages of small volume, light weight, small thickness, and low consumption, LCDs have been greatly developed in recent years. Being a passive electronic display device, an LCD device employs a backlight module to provide a light source. The backlight module is divided into a direct-light backlight module and an edge-light backlight module in accordance with the light incident mode. The edge-light backlight module includes a light guide panel and a light emitting diode (LED) lightbar arranged on the side of the light guide panel. The LED lightbar is used as a light source of the backlight module. 
       FIG. 1  shows a reflection-light backlight module. A reflector  100  is used in the structure of the reflection-light module. The reflector  100  includes two parts; one part is a reflection part  110 , the inside surface of the reflection part  110  is a reflection surface  111 , and the reflection surface  111  is used for reflecting the light emitted by an LED  320  into a light guide panel (LGP)  400 ; the other part is a horizontal extension part  120  is used for receiving an LED lightbar  300  and a printed circuit board (PCB)  310  thereon. 
     Because the reflector  100  is generally made of thin material, the stability of the size of an opening (a notch formed by bending the reflection part  110  relative to the extension part  120 ) is poor. The edge of the reflection part  110  obliquely arranged on the reflector  100  is provided with a small folding wall  112  inserting into an opening  210  of a shielding part  201  of a rubber frame  200 , and the rubber frame  200  is also formed with an inclined surface  220  of which the shape is similar to the inclined shape of the reflection part  110  on the back of the reflection part  110  of the reflector  100 , to limit the deformation of the reflection part  110  of the reflector  100 , and also limit the size variation of the opening of the reflector  100 . 
     The structure has the advantage of easy assembly, namely the parts are only stacked one by one. However, because a gap is still reserved between the reflector  100  and the LGP  400 , the rubber frame  200  is positioned by clamping hooks, a distance is reserved between the clamping hooks because of the requirement of structure design, and partial clamping hooks are not closely clamped because of the process capability tolerance factor. Thus, the rubber frame  200  cannot effectively press the LGP  400 . Therefore, partial light is emitted from the gap between the reflector  100  and the LGP  400 , resulting in light leakage. 
     SUMMARY 
     In view of the above-described problems, the aim of the invention is to provide a reflection-light backlight module and an LCD device with a high light utilization rate. 
     The aim of the invention is achieved by the following technical scheme. A reflection-light backlight module comprises an LGP, and a reflector arranged on the light incident surface of the LGP; the reflector comprises a reflection part, a first extension part which is connected with the front end of the reflection part, and a second extension part which is connected to the back end of the reflection part and arranged opposite to the first extension part; the first extension part and the second extension part clamp the LGP from the light emitting side of the LGP and the other side opposite to the light emitting side. 
     Preferably, the joint of the second extension part and the reflection part is provided with a limit part for limiting the position of the LGP. Thus, the positioning reliability of the LGP is increased, and the LGP is limited by the limit part when heat expansion occurs so that the LGP cannot knock and damage the LED. 
     Preferably, the inside surface of the limit part is in parallel with the light incident surface of the LGP. Mutually parallel interference enables the limit part to limit the position more reliably. 
     Preferably, the reflection surface of the reflection part comprises a plurality of planes with different inclination angles. The plurality of planes side by side with different inclination angles are selected in accordance with the light angle of the LED, to enable the reflection surface to reflect the light of the LED into the LGP to a maximum extent, thereby avoiding the light loss caused by multiple reflection. 
     Preferably, the reflection surface of the reflection part is a concave curved surface. The concave curved surface has good reflection and condensation effects. 
     Preferably, the backlight module comprises a PCB, and a reflection sheet; components clamped between the first extension part and the second extension part of the reflector comprise the PCB, the reflection sheet, and the LGP. The PCB, the reflection sheet and the like are directly integrated via the reflector without fixing the PCB by other parts, thereby saving materials and processes. 
     Preferably, the backlight module comprises a PCB, and a reflection sheet; components clamped between the first extension part and the second extension part of the reflector comprise the reflection sheet and the LGP. The PCB is arranged below the first extension part, and the first extension part is provided with a through hole for receiving the LED on the PCB. The PCB is arranged below the reflector, thereby reducing the number of the components clamped by the reflector, and then reducing the opening of the reflector. Thus, the phenomenon can be avoided that effective clamping and shading effects cannot be effectively formed because the structural strength of the reflector is influenced by the oversize opening, and the reliability of the reflector can be improved. 
     Preferably, the backlight module comprises a backplane; the backplane is provided with an opening for fixing the PCB, and the PCB is fixed on the backplane. Thus, the PCB can be stably fixed inside the backlight module, thereby providing a reliable light source. 
     Preferably, the first extension part is riveted with a bolt in the position corresponding to a screw hole, and the PCB is locked between the backplane and the first extension part by the bolt. The PCB is locked from both sides, so that the fixing reliability of the PCB is increased, and the PCB is more accurately positioned relative to the reflector. Thus, the LED on the PCB is positioned in an optimum position. 
     Preferably, the end of the second extension part is provided with a bent clamping hook, and the PCB is fixed below the second extension part by the clamping hook. Thus, the assembly procedure of the PCB is saved, and thus the production efficiency is improved. 
     Preferably, the backlight module comprises an optical film; the optical film is arranged on the second extension part. Therefore, the distance between the optical film and the light emitting surface of the LGP is reduced, thereby reducing the light loss, and increasing the brightness of the backlight module. 
     Preferably, the reflector is made of metal material with good heat conductivity or plastic material with high reflectance. The reflector made of metal material has good heat-conducting property and reduces temperature, and the reflector made of plastic material has low cost. 
     A liquid crystal display device comprises the aforementioned backlight module. 
     In the invention, because the outer edge of the reflection part of the reflector of the backlight module is provided with an extension part used for shading light, the gap between the edge of the reflection part of the reflector and the light incident surface of the LGP is shaded; thus, light is prevented from leaking from the gap, and the utilization rate of the light source is increased. Therefore, the brightness of the backlight module and the display effect of the LCD device are increased. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
         FIG. 1  is a simplified structure diagram of a conventional reflection-light backlight module; 
         FIG. 2  is a simplified structure diagram of a backlight module of a first example of the invention; 
         FIG. 3  is a simplified structure diagram of a reflector of a backlight module of a first example of the invention; 
         FIG. 4  is a simplified structure diagram of a backlight module of a second example of the invention; 
         FIG. 5  is a simplified structure diagram of a first reflector of a backlight module of a second example of the invention; 
         FIG. 6  is a simplified structure diagram of a second reflector of a second example of the invention; 
         FIG. 7  is a simplified structure diagram of a third reflector of a second example of the invention; 
         FIG. 8  is a simplified structure diagram of a reflector with a reflection surface which is a concave curved surface of the invention; and 
         FIG. 9  is a simplified structure diagram of a reflector with a reflection surface comprising a plurality of planes of the invention. 
     
    
    
     Legends:  100 . reflector;  110 . reflection part;  111 . reflection surface;  120  first extension part;  130 . second extension part;  140 . limit part;  170 . clamping hook;  180 . through hole;  200 . rubber frame;  201 . shading part;  300 . lightbar;  310 . PCB;  320 . LED;  350 . reflection sheet;  360 . double-sided adhesive tape;  400 . LGP;  410 . light emitting surface;  420 . optical film;  500 . backplane;  510 . screw;  520 . bolt. 
     DETAILED DESCRIPTION 
     The invention will further be described in detail in accordance with the figures and the preferred examples. 
       FIG. 2  and  FIG. 3  show a reflection-light backlight module of a LCD device. The backlight module comprises a backplane  500 , a lightbar  300  arranged in the backplane  500 , an LGP  400 , and a reflector  100  which is used for reflecting the light emitted by the LED  320  on the lightbar  300  into the LGP  400 . A rubber frame  200  tightly presses the reflector  200 , the LGP  400 , and the optical film arranged on the light emitting surface of the LGP  400  to limit the position of the LGP  400 . The reflector  100  comprises a reflection part  110 . The inside surface of the reflection part  110  is a reflection surface  111 , and the reflection surface  111  is obliquely arranged relative to the light incident surface of the LGP  400 . The reflector  100  further comprises a first extension part  120  which is connected to the front end of the reflection part  110 , and a second extension part  130  which is connected with the back end of the reflection part  110  and arranged opposite to the first extension part  120 . The first extension part  120  and the second extension part  130  clamp the LGP  400  from the light emitting side of the LGP  400  and the other side opposite to the light emitting side; namely the first extension part  120  and the second extension part  130  clamp a plurality of components comprising the LGP  400 , and the distance between the first extension part  120  and the second extension part  130  is less than the thickness of the plurality of components clamped by the two extension parts. 
     The following examples are the specific examples of the invention: 
     Example 1 
       FIG. 2  shows a first example of the invention. The Figure shows a reflection-light backlight module of a LCD device. The backlight module comprises a backplane  500 , a lightbar  300  arranged in the backplane  500 , an LGP  400 , and a reflector  100  which is used for reflecting the light emitted by the LED  320  on the lightbar  300  into the LGP  400 . A rubber frame  200  tightly presses the reflector  200 , the LGP  400 , and the optical film arranged on the light emitting surface of the LGP  400  to limit the position of the LGP  400 . The reflector  100  comprises a reflection part  110 , and the inside surface of the reflection part  110  is a smooth reflection surface  111 . The reflection surface  111  is obliquely arranged relative to the light incident surface of the LGP  400 , and the inclination angle between the reflection surface  111  and the LGP  400  is set to an optimal angle in accordance with the light angle of the LED  310  to achieve the optimal reflection efficiency. The reflector  100  further comprises a first extension part  120  which is connected to the front end of the reflection part  110 , and a second extension part  130  which is connected with the back end of the reflection part  110  and is arranged opposite to the first extension part  120 . The first extension part  120  and the second extension part  130  clamp the components comprising the PCB  310 , the reflection sheet  350 , the LGP  400  and the like. The PCB  310  is stuck on the first extension part  120  by a double-sided adhesive tape  360  or glue. As shown in  FIG. 3 , the opening distance between the first extension part  120  and the second extension part  130  is d 1 , and the opening distance d 1  is less than the total thickness of the PCB  310 , the reflection sheet  350 , the LGP  400  and the like which are stacked together. Thus, the reflector  100  can form effective clamping force, to closely clamp the PCB  310 , the reflection sheet  350 , the LGP  400  and the like together. Therefore, a light leakage gap between the reflector  100  and the LGP  400  is avoided, and the utilization rate of the light source of the backlight module is increased. Thus, the brightness of the backlight module and the display effect of the LCD device are increased. Furthermore, a complicated mode, for example, using screws, etc. to fix the lightbar  300 , is omitted. 
     As shown in  FIG. 2  and  FIG. 3 , on the reflector  100 , the joint of the reflection part  110  and the second extension part  130  is provided with a limit part  140  which is used for limiting the position of the LGP  400 , and the inside surface of the limit part  140  is in parallel with the light incident surface of the LGP  400 . The installation accuracy of the LGP  400  can be increased via the limiting function of the limit part  140 , and the LGP  400  can be limited by the limit part  140  when heat expansion occurs so that the LGP  400  cannot knock and damage the LED  320 . 
     Example 2 
       FIG. 4  shows a second example of the invention. The second example is different from the first example in that:  FIG. 5  shows a reflector  100  of the second example, the opening distance d 2  of the reflector  100  is less than the opening distance d 1  of the first example, and the reason is that: as shows in  FIG. 4 , the components clamped by the reflector  100  comprise the reflection sheet  350 , and the LGP  400 ; the PCB  310  is arranged below the first extension part  120 , the first extension part  120  is provided with a through hole for receiving the LED  320  on the PCB  310 , and the LED  320  is arranged in the reflector  100  via the through hole. Thus, the opening distance d 2  of the reflector  100  is reduced as far as possible, and the structural strength of the reflector  100  is increased, thereby increasing the clamping force of the reflector  100 . Therefore, the reflector  100  is closely attached to the LGP  400 , the gap is avoided, and thus the light utilization rate of the backlight module and the brightness of the backlight module are increased. 
     For the second example, it is necessary to consider the fixing mode of the PCB  310 . Because the LED  320  is fixed on the PCB  310 , the position accuracy and the fixing reliability of the PCB have a direct influence on the light reflection effect of the reflector to the LED  320 . As shown in  FIG. 4 , in the example, the backplane  500  is provided with a screw hole to lock the PCB  310 ; meanwhile, the corresponding position of the second extension part  120  is welded with a tubular bolt  520 , and the PCB  310  is locked between the second extension part  120  and the backplane  500  by a screw  510 . The fixing reliability of the PCB  310  is increased, and the PCB  310  is more accurately positioned relative to the reflector. Thus, the LED on the PCB  310  is positioned in an optimum position. 
     In the second example, as shown in  FIG. 6  and  FIG. 7 , the back end of the first extension part  120  of the reflector  100  is provided with a bent clamping hook  170 . The PCB is arranged inside the clamping hook  170  and positioned below the first extension part  120 . The first extension part  120  is provided with a through hole  180  for receiving the LED on the PCB. By the mode of directly fixing the PCB by the clamping hook  170 , the assembly time of the PCB can be saved. 
     The above examples are two specific examples of the invention. 
     In the two examples of the invention, the angle of the reflection surface of the reflector can be set in accordance with the position of the LED, to achieve the optimal reflection efficiency, and avoid the loss of the light source caused by multiple reflections. Similarly, to achieve better focused reflection to enable the light source to be concentrately reflected into the light incident surface of the LGP, the reflection surface of the reflector can be, besides the inclined surface of the first example and the second example, in a shape of the concave curved surface as shown in  FIG. 8 , or can be in a shape of the reflection surface with a plurality of planes comprising various inclination angles as shown in  FIG. 9 . The reflection surface of such a shape can concentrately reflect the light of multiple angles into the light incident surface of the LGP. 
     In the two examples of the invention, as shown in  FIG. 2  and  FIG. 4 , the optical film  420  of the backlight module can be arranged on the second extension part  130 . Thus, the distance between the optical film  420  and the emitting surface  410  of the LGP  400  will be reduced; therefore, the backlight module can be prevented from losing too much brightness. As shown in  FIG. 1 , the optical film of the conventional backlight module is arranged above the shading part  201  of the rubber frame  200 . However, the shading part  201  is used for providing pressing force in addition to shading light; thus, the thickness of the shading part  201  is large, causing the distance between the optical film and the light emitting surface  410  of the LGP  400  to be far. In the two examples of the invention, the problem has been solved. 
     In the two examples of the invention, the reflector  100  is made of material with good heat conductivity such as pure aluminum, pure copper, etc., and has higher heat conduction efficiency than that of the backplane. Thus, better heat conduction effect can be obtained, and thus the temperature of the backlight module can be reduced. Of course, considering cost, the reflector can be made of plastic material with lower cost and high reflectance. 
     The invention is described in detail in accordance with the above contents with the specific preferred examples. However, this invention is not limited to the specific examples. For the ordinary technical personnel of the technical field of the invention, on the premise of keeping the conception of the invention, the technical personnel can also make simple deductions or replacements, and all of which should be considered to belong to the protection scope of the invention.