Patent Publication Number: US-2015062969-A1

Title: Backlight module

Description:
RELATED APPLICATIONS 
     This application claims priority to Taiwan Application Serial Number 102131871, filed Sep. 4, 2013, which is herein incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     Embodiments of the present invention relate to a backlight module. More particularly, embodiments of the present invention relate to a backlight module of a display apparatus. 
     2. Description of Related Art 
     The LCD (liquid crystal display) is one of the most popular display apparatus, in which a LCD panel and a backlight module are included. In particular, the LCD panel is disposed on the backlight module which provides an illumination to the LCD panel, such that the viewer can see the image through the LCD panel. 
     A typical backlight module includes a light source, a light guide plate, a back bezel and a frame. The light guide plate has two opposite main surfaces and plural side surfaces connected to the main surfaces. The light source can be disposed on the main surface of the light guide plate that is opposite to the LCD panel, so as to form a direct type backlight module. Alternatively, the light source can be disposed on the side surface of the light guide plate as well, so as to form an edge lit type backlight module. In a typical backlight module, as shown in  FIG. 1 , the light guide plate  21  is supported by the cushion  26 , and the cushion  26  is disposed on the back bezel  22 . The back bezel  22  and the frames  23 ,  24  can be fastened by the screw  25 . In order to fasten the back bezel  22  and the frames  23 ,  24  by the screw  25 , the back bezel  22  is tapped and drilled to form the threaded hole. 
     However, during the tapping and drilling process, powdery debris is introduced. If the powdery debris is not removed, it may enter the backlight module with the screw  25  being screwed through the back bezel  22 , which may damage the light guide plate  21  or the optical films on the light guide plate  21 . 
     SUMMARY 
     Embodiments of the invention provide a backlight module that can prevent the debris generated during the drilling and tapping process from damaging the light guide plate. 
     In accordance with one embodiments of the present invention, a backlight module includes a back bezel, at least one frame, at least one fastener, a cushion and a light guide plate. The back bezel includes a bottom plate and at least one lateral plate adjoined to the bottom plate. The frame abuts against the lateral plate. The fastener fastens the frame and the back bezel. The cushion is disposed on the bottom plate. The cushion has a cavity. A part of the fastener is located in the cavity. The light guide plate is disposed on one side of the cushion opposite to the bottom plate. 
     In the foregoing embodiment, because the fastener screwed through the back bezel is located in the cavity, even though the debris is generated during the drilling and tapping process, and the debris can still get into the inside of the back bezel when screwing the screw. Therefore, the debris can be confined in the cavity, and do not damage the light guide plate on the cushion. Therefore, the backlight module in the foregoing embodiment can prevent the debris generated during the drilling and tapping process from damaging the light guide plate. 
     It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows: 
         FIG. 1  is a perspective cross-sectional view of a typical display apparatus; 
         FIG. 2  is a top view of a display apparatus in accordance with one embodiment of the present invention; 
         FIG. 3  is a perspective cross-sectional view taken along A-A′ ling in  FIG. 2 ; 
         FIG. 4  is a perspective view of the cushion in  FIG. 3 ; 
         FIG. 5  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention; 
         FIG. 6  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention; 
         FIG. 7  is a perspective view of the cushion in accordance with another embodiment of the present invention; 
         FIG. 8  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention; 
         FIG. 9  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention; 
         FIG. 10  is an explosive view of the cushion shown in  FIG. 9 ; 
         FIG. 11  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention; 
         FIG. 12  is an explosive view of the cushion in accordance with another embodiment of the present invention; 
         FIG. 13  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention; and 
         FIG. 14  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
       FIG. 2  is a top view of a display apparatus in accordance with one embodiment of the present invention.  FIG. 3  is a perspective cross-sectional view taken along A-A′ line in  FIG. 2 . As shown in  FIGS. 2 and 3 , in this embodiment, the backlight module  10  is located under the display panel  910 . The backlight module  10  may include a back bezel  100 , at least one frame  200 , at least one fastener  300 , a cushion  400  and a light guide plate  500 . The back bezel  100  may include a bottom plate  110  and at least one lateral plate  120 . As shown in  FIG. 3 , the lateral plate  120  is adjoined to the bottom plate  110 . In some embodiments, the lateral plate  120  may be substantially perpendicular to the bottom plate  110 . The frame  200  abuts against the lateral plate  120 . A front bezel  920  is disposed outside the display panel  910 . The fastener  300  fastens the front bezel  920  and the frame  200  to the lateral plate  120  of the back bezel  100 . The cushion  400  is disposed on the bottom plate  110 . The cushion  400  is located inside the lateral plate  120 , and the frame  200  is located outside the lateral plate  120  opposite to the cushion  400 . The cushion  400  includes a cavity  410 . A part of the fastener  300  is located in the cavity  410 . The light guide plate  500  is disposed on one side of the cushion  400  opposite to the bottom plate  110 , such that the cushion  400  can support the light guide plate  500 . 
     In this embodiment, the lateral plate  120  of the back bezel  100  abuts against the frame  200 . The lateral plate  120  has a threaded hole  122 , and the frame  200  has a hole  212 , and the front bezel  920  has a hole  922  as well. The fastener  300  is located through the holes  922 ,  212  and the threaded hole  122 , so as to fasten the front bezel  920  and the frame  200  to the back bezel  100 . In this embodiment, the threaded hole  122  of the lateral plate  120  can be formed by drilling and tapping process, and therefore, debris may remain in the threaded hole  122 . When the fastener  300  is screwed through the threaded hole  122 , it may move the debris away from the threaded hole  122 , and the debris may fall inside the lateral plate  120  opposite to the frame  200 . However, when the fastener  300  is screwed though the threaded hole  122 , it is accommodated in the cavity  410 , and therefore, even though the fastener  300  may move the debris inside the back bezel  100  opposite to the frame  200 , these debris can be confined in the cavity  410 , and do not damage the light guide plate  500  on the cushion  400 . Therefore, the backlight module in the foregoing embodiment can effectively prevent the debris from damaging the light guide plate  500 , such as scratching the light guide plate  500 . 
     As shown in  FIG. 3 , the fastener  300  may be a screw. For example, the fastener  300  may includes a screw head  301  and a bolt  302 . The screw head  301  is connected to the bolt  302 . When the fastener  300  fastens the front bezel  920  and the frame  200  to the lateral plate  120 , the screw head  301  abuts against the outside of the front bezel  920  opposite to the frame  200 , and the bolt  320  is located through the holes  922 ,  212  and the threaded hole  122 . The tip of the bolt  302  farthest from the screw head  301  is exposed in the cavity  410 . 
     As shown in  FIG. 3 , the cushion  400  includes a surface  420  faced to the lateral plate  120 . In some embodiments, the surface  420  of the cushion  400  abuts against the lateral plate  120 , so that there is no gap between the surface  420  of the cushion  400  and the lateral plate  120 , which further prevents the debris in the cavity  410  from moving above the cushion  400  and damaging the light guide plate  500 . It is understood that “an element abuts against another element” means that these two elements are in contact with each other. For example, “the surface  420  of the cushion  400  abuts against the lateral plate  120  means that the surface  420  of the cushion  400  is in contact with the lateral plate  120 , and therefore, there is no gap between the surface  420  of the cushion  400  and the lateral plate  120 . In this embodiment, the cushion  400  is integrally formed as one piece, and the material thereof can be, but is not limited to be, the foaming material for providing the buffering ability. 
     In some embodiments, as shown in  FIG. 3 , the light guide plate  500  has at least one light incident surface  502  and a light emitting surface  504  adjoined to the light incident surface  502 . The backlight module  10  includes at least one optical film  710 . The optical film  710  is disposed on the light emitting surface  504  of the light guide plate  500 . The backlight module  10  includes a plurality of light sources  610  (See  FIG. 2 ). Each of the light sources  610  has a lighting surface  612 . The lighting surfaces  612  are substantially parallel to the light incident surface  502  of the light guide plate  500  (See  FIG. 3 ), so that the light sources  610  can emit lights toward the light incident surface  502 , and the lights emitted into the light guide plate  500  can go into the optical films  710  (See  FIG. 3 ) through the light emitting surface  504 . Then, the lights can enter into the display panel  910  through the optical films  710 . As such, the backlight module  10  can be, but is not limited to be, a direct type backlight module. In some embodiments, the light sources  610  can be, but are not limited to be, LEDs (light emitting diodes). In some embodiments, one of the optical films  710  can be a diffuser, BEF (brightness enhancement film) or other film, and it can be chosen based on demands. 
     In some embodiments, as shown in  FIG. 3 , a orthogonal projection of the frame  200  and a orthogonal projection of the optical films  710  onto the light guide plate  500  are overlapped. As such, the frame  200  can press the optical films  710  onto the light guide plate  500 . Moreover, in some embodiments, the backlight module  10  may include a protector  722 . The protector  722  is sandwiched between the frame  200  and the optical films  710 , so as to protect the optical films  710 . Further, a protector  724  can be alternatively sandwiched between the display panel  910  and the frame  200 , and a protector  726  can be alternatively sandwiched between the display panel  910  and the front bezel  920 . In other words, the display panel  910  is sandwiched between the protectors  724  and  726 , such that it can be fixed and protected by the protectors  724  and  726 . The protectors  724  and  726  can be, but are not limited to be, formed by rubber, sponge or foaming material. 
       FIG. 4  is a perspective view of the cushion  400  in  FIG. 3 . As shown in  FIG. 4 , the cushion  400  has a surface  430 . The surface  430  is adjoined to the surface  420 , and in some embodiments, the surfaces  430  and  420  are substantially perpendicular to each other. As shown in  FIG. 3 , the surface  430  is faced to the light guide plate  500 . In some embodiments, the light guide plate  500  can be in contact with the surface  430  of the cushion  400 . 
       FIG. 5  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention. The main difference between this embodiment and which is shown in  FIG. 3  is that a reflective layer  730  is disposed on the surface  430  of the cushion  400 . The reflective layer  730  can reflect the lights emitted by the light sources  610  (See  FIG. 2 ) toward the optical films  710 . The surface  430  of the cushion  400  has a first area  432  and a second area  434 . The second area  434  is adjoined to the first area  432 . In this embodiment, the reflective layer  730  is only disposed on the first area  432  of the surface  430  of the cushion  400 . The light guide plate  500  is located on the reflective layer  730 . 
       FIG. 6  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention. The main difference between this embodiment and which is shown in  FIG. 5  is that the reflective layer  730   a  covers the whole surface  430  of the cushion  400 . 
       FIG. 7  is a perspective view of the cushion  400   a  in accordance with another embodiment of the present invention. The main difference between the cushion  400   a  and the cushion  400  is that the cushion  400   a  includes an adhesive layer  442 . The adhesive layer  442  is disposed on the surface  420  of the cushion  400   a , and this surface  420  is faced to and abuts against the lateral plate  120  (See  FIG. 6 ). As such, if a gap is formed between the surface  420  of the cushion  400   a  and the lateral plate  120 , even though debris may move from the cavity  410  to the gap, it can be adhered to the adhesive layer  442 . Therefore, the adhesive layer  442  can protect the light guide plate  500  (See  FIG. 6 ) on the surface  430  of the cushion  400   a  from the debris. Further, the adhesive layer  442  can adhere the cushion  400   a  to the lateral plate  120  as well, so as to fix the cushion  400   a . It is noted that, in this embodiment, the adhesive layer  442  is depicted as only covering a partial surface  420  of the cushion  400   a  in order to facilitate the reader can clearly see the adhesive layer  442  in  FIG. 7 . In other embodiments, the adhesive layer  442  can also cover the whole surface  420  of the cushion  400   a.    
     In some embodiments, as shown in  FIG. 7 , the cushion  400   a  may include another adhesive layer  444 . The adhesive layer  444  is disposed on the wall defining the cavity  410 . In this configuration, when the debris falls into the cavity  410 , it can be adhered to the adhesive layer  444  that is disposed on the wall defining the cavity  410 . Hence, the adhesive layer  444  can prevent the debris from moving and can thereby protect the light guide plate  500  (See  FIG. 6 ) on the surface  430  of the cushion  400   a  from the debris. It is noted that, in this embodiment, the adhesive layer  444  is depicted as only covering a partial wall defining the cavity  410  in order to facilitate the reader can clearly see the adhesive layer  444  in  FIG. 7 . In other embodiments, the adhesive layer  444  can also cover the whole wall defining the cavity  410 . 
       FIG. 8  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention. The main difference between this embodiment and which is shown in  FIG. 3  is that the cushion  400   b  has a blocking structure  450  on the surface  430  of the cushion  400   b  faced to the light guide plate  500 , so as to position the light guide plate  500 , thereby preventing the light guide plate  500  from moving on the cushion  400   b . In particular, the light guide plate  500  is located on the first area  432  of the surface  430 . The blocking structure  450  is disposed on the second area  434  of the surface  430 . In other words, the blocking structure  450  is located on the area of the cushion  400   b  not covered by the light guide plate  500 . As such, when the light guide plate  500  is located on the first area  432 , the light guide plate  500  abuts against the blocking structure  450 , thereby positioning the light guide plate  500 . Therefore, even if the light guide plate  500  may shake during the transferring process of the display apparatus, the blocking structure  450  may block the light guide plate  500 , so as to protect the lateral plate  120 . 
     In some embodiments, as shown in  FIG. 8 , the blocking structure  450  may be an uneven microstructure, and the protruded portion of the uneven microstructure can block the light guide plate  500 . The uneven microstructure may be, but is not limited to be, formed on the surface  430  of the cushion  400   b  by rolling process. In some embodiments, the blocking structure  450  may be a rib that is at least protruded on the boundary between the first area  432  and the second area  434 , so as to block the light guide plate  500 . 
       FIG. 9  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention. As shown in  FIG. 9 , the main difference between this embodiment and which is shown in  FIG. 3  is that the cushion  800  includes a bottom buffering structure  810  and a top buffering structure  820  attached to each other. In other words, the cushion  800  is not integrally formed as one piece. The top buffering structure  820  is disposed on the bottom buffering structure  810 . The cavity  812  is located on the bottom buffering structure  810 . The top buffering structure  820  covers the cavity  812  and abuts against the lateral plate  120 . 
     Because the top buffering structure  820  abuts against the lateral plate  120 , no gap is formed between the top buffering structure  820  and the lateral plate  120 , which prevents the debris from moving above the top damping structure  820  and from damaging the light guide plate  500 . 
     In some embodiments, not only the top buffering structure  820  abuts against the lateral plate  120 , but the bottom buffering structure  810  also abuts against the lateral plate  120 , so as to prevent the debris in the cavity  812  from escaping out of the cavity  812 . 
     In some embodiments, as shown in  FIG. 9 , the top buffering structure  820  has a surface  821 . The surface  821  of the top buffering structure  820  is faced to the light guide plate  500 . In particular, in some embodiments, the light guide plate  500  can be in contact with the surface  821  of the top buffering structure  820 . 
       FIG. 10  is an explosive view of the cushion  800  shown in  FIG. 9 . As shown in  FIG. 10 , the cavity  812  has a first opening  814  and a second opening  816 . The first opening  814  is faced to the fastener  300  (See  FIG. 9 ). The top buffering structure  820  covers the second opening  816 . In this configuration, when the fastener  300  is screwed through the threaded hole  122  (See  FIG. 9 ), such that the debris in the threaded hole  122  falls into the cavity  812  through the first opening  814 , the top buffering structure  820  can prevent the debris in the cavity  812  from escaping out of the cavity  812  through the second opening  816 . 
     In some embodiments, as shown in  FIG. 10 , the bottom buffering structure  810  has surfaces  811 ,  813  and  815 . The surfaces  811  and  813  are opposite to each other, and the surface  815  connects the surfaces  811  and  813 . The top buffering structure  820  is located on the surface  811  of the bottom buffering structure  810 . The cavity  812  extends through the surfaces  811  and  813  of the bottom buffering structure  810 . Because the cavity  812  extends through the surfaces  811  and  813 , the cavity  812  can be formed by punching process, rather than by drilling the surface  815  inwardly. For example, the cavity  812  can be formed by punching the surface  811  downwardly, or by punching the surface  813  upwardly, so that the cavity  812  can extend through the surfaces  811  and  813 , and the punching process is simpler than drilling the surface  815  inwardly. In some embodiments, the material of the bottom buffering structure  810  and which of the top buffering structure  820  can be, but are not limited to be, the foaming material for providing the buffering ability. 
     In some embodiments, the bottom buffering structure  810  includes at least two protrusions  817 . The cavity  812  is located between the protrusions  817 . The protrusions  817  abut against the lateral plate  120  (See  FIG. 9 ). 
       FIG. 11  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention. As shown in  FIG. 11 , the main difference between this embodiment and which is shown in  FIG. 10  is that a reflective layer  730  is disposed on the surface  821  of the top buffering structure  820 . The reflective layer  730  can reflect the lights emitted by the light sources  610  (See  FIG. 2 ) toward the optical films  710 . In this embodiment, the reflective layer  730  is only located on a partial area of the surface  821  of the top buffering structure  820 , such as the area that is covered by the light guide plate  500 . In other embodiments, the reflective layer  730  can cover the whole surface  821  of the top buffering structure  820 . 
       FIG. 12  is an explosive view of the cushion  800   a  in accordance with another embodiment of the present invention. As show in  FIG. 12 , the main difference between the cushion  800   a  and the foregoing cushion  800  is that the bottom buffering structure  810   a  includes an adhesive layer  818 . The adhesive layer  818  is disposed on the surface  815  of the bottom buffering structure  810   a , and this surface  815  is faced to the lateral plate  120  (See  FIG. 11 ). As such, if a gap is formed between the surface  815  of the bottom buffering structure  810   a  and the lateral plate  120 , even though some debris may move from the cavity  812  to the gap, it can be adhered to the adhesive layer  818 . Therefore, the adhesive layer  818  can protect the light guide plate  500  (See  FIG. 11 ). Further, the adhesive layer  818  can adhere the bottom buffering structure  810   a  to the lateral plate  120  as well, so as to fix the bottom buffering structure  810   a . It is noted that, in this embodiment, the adhesive layer  818  is depicted as only covering a partial surface  815  of the bottom buffering structure  810   a  in order to facilitate the reader can clearly see the adhesive layer  818  in  FIG. 12 . In other embodiments, the adhesive layer  818  can also cover the whole surface  815  of the bottom buffering structure  810   a.    
     In some embodiments, as shown in  FIG. 12 , the bottom buffering structure  810   a  may include another adhesive layer  819 . The adhesive layer  819  is disposed on the wall defining the cavity  812 . In this configuration, when the debris falls into the cavity  812 , it can be adhered to the adhesive layer  819  disposed on the wall defining the cavity  812 . Hence, the adhesive layer  819  can prevent the debris from moving and can thereby protect the light guide plate  500  (See  FIG. 11 ). It is noted that, in this embodiment, the adhesive layer  819  is depicted as only covering a partial wall defining the cavity  812  in order to facilitate the reader can clearly see the adhesive layer  819 . In other embodiments, the adhesive layer  819  can also cover the whole wall defining the cavity  812 . 
     In some embodiments, as shown in  FIG. 12 , the top buffering structure  820   a  includes a surface  822  and an adhesive layer  824 . The surface  822  of the top buffering structure  820   a  is faced to the lateral plate  120  (See  FIG. 11 ). The adhesive layer  824  is disposed on the surface  822  of the top buffering structure  820   a . As such, if a gap is formed between the surface  822  of the top buffering structure  820   a  and the lateral plate  120 , even though the debris may move from the cavity  812  to the gap, it can be adhered to the adhesive layer  824 . Therefore, the adhesive layer  824  can protect the light guide plate  500  (See  FIG. 11 ). Further, the adhesive layer  824  can adhere the top buffering structure  820   a  to the lateral plate  120  as well, so as to fix the top buffering structure  820   a . It is noted that, in this embodiment, the adhesive layer  824  is depicted as only covering a partial surface  822  of the top buffering structure  820   a  in order to facilitate the reader can clearly see the adhesive layer  824 . In other embodiments, the adhesive layer  824  can also cover the whole surface  822  of the top buffering structure  820   a.    
       FIG. 13  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention. As shown in  FIG. 13 , the main difference between this embodiment and which is shown in  FIG. 9  is the cushion  800   b . In particular, the top buffering structure  820   b  has a blocking structure  827  thereon for positioning the light guide plate  500 , thereby preventing the light guide plate  500  from moving on the top buffering structure  820   b . In particular, the surface  821  of the top buffering structure  820   b  has a first area  823  and a second area  825 . The first area  823  is adjoined to the second area  825 . The light guide plate  500  is located on the first area  823 . The blocking structure  827  is disposed on the second area  825 . In other words, the blocking structure  827  is located on the area of the top buffering structure  820   b  that is not covered by the light guide plate  500 . As such, when the light guide plate  500  is located on the first area  823 , the light guide plate  500  can abut against the blocking structure  827  for positioning itself. Therefore, even if the light guide plate  500  may shake during the transferring process of the display apparatus, the blocking structure  827  may block the light guide plate  500 , so as to protect the lateral plate  120 . 
     In some embodiments, as shown in  FIG. 13 , the blocking structure  827  may be an uneven microstructure, and the protruded portion of the uneven microstructure can block the light guide plate  500 . The uneven microstructure may be, but is not limited to be, formed on the surface  821  of the top buffering structure  820   b  by rolling process. In some embodiments, the blocking structure  827  may be a rib that is at least protruded on the boundary between the first area  823  and the second area  825  of the surface  821 , so as to block the light guide plate  500 . 
       FIG. 14  is a perspective cross-sectional view of the display apparatus in accordance with another embodiment of the present invention. As shown in  FIG. 14 , the main difference between this embodiment and which is shown in  FIG. 9  is the cushion  800   c . In particular, the top buffering structure  820   c  includes two adhesive layers  826  and  828 . The glue layer  826  is faced to the bottom buffering structure  810 . The glue layer  828  is faced to the light guide plate  500 . In other words, the top buffering structure  820   c  can be a double coated tape, in which the adhesive layers  826  and  828  can respectively adhere to the bottom buffering structure  810  and the light guide plate  500 . By the adhesive layers  826  and  828 , the top buffering structure  820   c  can fix the light guide plate  500 , and can adhere to the debris escaping out of the cavity  812 , so as to protect the light guide plate  500  from the debris. 
     In some embodiments, as shown in  FIG. 2 , the light sources  610  can be disposed on a heat dissipation structure  620 , and the heat dissipation structure  620  is disposed on the bottom plate  110  (See  FIG. 3 ). As such, when the light sources  610  emit lights, the generated heat can be transferred to the bottom plate  110  via the heat dissipation structure  620 , so as to prevent the light sources  610  from overheated. In some embodiment, the heat dissipation structure  620  can be, but is not limited to be, a metal for transferring heat. 
     In some embodiments, a plurality of the lateral plates  120  (See  FIG. 3 ) can be respectively connected to different edges of the bottom plate  110  (See  FIG. 3 ). In order to improve the heat dissipation ability of the heat dissipation structure  620 , the heat dissipation structure  620  (See  FIG. 2 ) preferably abuts against one of the lateral plates  120  (See  FIG. 3 ), and preferably, the lateral plate  120  abutted by the heat dissipation structure  620  is the one that doesn&#39;t has the fastener  300  therethrough, so as to protect the heat dissipation structure  620 . Therefore, the cushion  400  (See  FIG. 3 ) and the heat dissipation structure  620  preferably abut against different lateral plates  120 . 
     Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims.