Abstract:
Provided is a flat-panel display for improving a structure of a shape of a through-hole of a backlight cover that is a resin-made member, which is passed through when making a PWB contact a metal plate member, so that a gasket can be mechanically fixed. This flat-panel display includes: a metal plate member ( 30 ) arranged on a rear side of a display panel; a non-conductive plate member ( 20 ) arranged so as to face a rear side of the metal plate member ( 30 ) and including a through-hole ( 42 ); a circuit board ( 50 ) arranged so as to face a rear side of the non-conductive plate member ( 20 ) ; and a gasket ( 90 ) arranged in the through-hole ( 42 ) and holding conduction of the metal plate member ( 30 ) and the circuit board ( 50 ), in which the non-conductive plate member ( 20 ) includes a gasket fixation portion ( 44 ) formed around the through-hole ( 42 ) in a convex shape.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a flat-panel display, and relates to, for example, a flat-panel display provided with a function of securing grounding by utilizing a gasket for a circuit board (printed wiring board) and a metal plate. 
         [0002]    BACKGROUND ART 
         [0003]    For a liquid crystal television of a direct-backlight type model, a configuration in which a resin-made backlight cover (middle cabinet) covers a metal plate member where an LED is arranged as a backlight and a main PWB (printed wiring board) is attached to the resin-made member has been known. 
         [0004]    With reference to  FIGS. 1 , description will be here given for a structure where a gasket  190  is attached with respect to a main PWB  150  in a liquid crystal display. As shown in  FIG. 1A , the gasket (conductive member)  190  is fixed to a PWB back surface  151  on which grounding (GND) of the main PWB  150  is formed with a double-sided adhesive tape. Then, as shown in  FIG. 1B , in a state where the gasket  190  is fixed to the main PWB  150 , in setting of a state where a resin-made back cabinet  120  is arranged on a rear side (upper side in the figure) of a metal plate member  130 , the gasket  190  is stuck to a predetermined region of the metal plate member  130  with a double-sided adhesive tape through a gasket through-hole  140  which is formed on the back cabinet  120 . As a result thereof, the structure becomes as shown in  FIG. 1C , in which the main PWB  150  and the metal plate member  130  appropriately make contact through the gasket  190  and conduction thereof is secured. 
         [0005]    This kind of technologies and various ones have been proposed. For example, there is a technology for seeking further thinning of a mobile communication terminal, which incorporates an antenna, while preventing a result of antenna characteristics (refer to PATENT LITERATURE 1). Specifically, a first resin-made cabinet obtained by insert-molding of a first sheet metal and a second resin-made cabinet obtained by insert-molding of a second sheet metal are provided. In addition, a circuit board, on which an antenna is printed, is held between the first resin-made cabinet and the second resin-made cabinet, and the first sheet metal, the second sheet metal and the antenna are electrically connected by a plurality of conductive gaskets. 
       CITATION LIST 
     Patent Literature  
       [0006]    PATENT LITERATURE 1: Japanese Laid-Open Patent Publication No. 2010-109760 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    Meanwhile, the fixation of the gasket  190  is performed to the main PWB  150  and the metal plate member  130  only with the double-sided adhesive tape. Furthermore, since the fixation is performed through the gasket through-hole  140  of the back cabinet  120 , in a television adopting such a structure, there are problems such as deterioration of adhesion of the double-sided adhesive tape and variations of a way of sticking at a time of assembling. For example, as shown in  FIG. 1D , it is also assumed that the gasket  190  comes off from the gasket through-hole  140  due to deformation or the like. When these problems become tangible, there is a risk that the gasket  190  which makes the main PWB  150  and the metal plate member  130  into conduction causes instability of contact and worsens unnecessary radiation or is in contact with other parts to exert a bad influence. Moreover, in order not to ship such a product to market, labor in an inspection process increases and countermeasure thereagainst has been required. 
         [0008]    Moreover, in the technology disclosed in PATENT LITERATURE 1, the gasket is used to thereby electrically connect separated conductive materials for effective use. 
         [0009]    Further, positioning is performed by the fixation with the double-sided adhesive tape or making a hole in a middle resin-made cabinet. However, it is impossible to suppress deformation due to compression of the gasket, and there is possibility of being in contact with a region which is not contactable, so that another technology has been desired. Further, in a case where an adhesive material such as a double-sided adhesive tape comes off, there is possibility that the gasket moves due to vibrations or the like, and thus countermeasure thereagainst becomes necessary, so that another technology has been desired. 
         [0010]    The present invention is made in view of the circumstances above, and aims to provide a technology which solves the aforementioned problems. 
       SOLUTION TO PROBLEM 
       [0011]    A flat-panel display of the present invention includes: a metal plate member which is arranged on a rear side of a display panel; a non-conductive plate member which is arranged so as to face a rear side with respect to the metal plate member and which is provided with a through-hole; a circuit board which is arranged so as to face a rear side with respect to the non-conductive plate member; and a gasket which is arranged in the through-hole and which holds conduction of the metal plate member and the circuit board, in which the non-conductive plate member is provided with a gasket fixation portion which is formed around the through-hole in a convex shape. 
         [0012]    Moreover, the gasket may be thicker than the gasket fixation portion. 
         [0013]    Moreover, the gasket fixation portion may be a wall surface which is formed around the through-hole. 
         [0014]    Moreover, the gasket fixation portion may be provided with a claw shape for locking a side surface of the gasket. 
         [0015]    Moreover, a hole which is formed in the gasket fixation portion and a bar-shaped body which passes through the hole and sticks through the gasket may be included. 
       ADVANTAGEOUS EFFECT OF INVENTION 
       [0016]    According to the present invention, it is possible to provide a technology of improving a structure of a shape of a through-hole of a backlight cover (middle cabinet) that is a resin-made member, which is passed through when making a circuit board and a metal plate member in contact, so that a gasket is able to be mechanically fixed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]    [ FIGS. 1 ] are views showing a grounding structure of a metal plate member of a backlight and a main PWB by a gasket in a liquid crystal television according to a background art. 
           [0018]    [ FIG. 2 ] is an exploded perspective view of a liquid crystal television according to a first embodiment. 
           [0019]    [ FIG. 3 ] is a view showing a grounding structure of a metal plate member of a backlight and a PWB by a gasket in the liquid crystal television according to the first embodiment. 
           [0020]    [ FIGS. 4 ] are views focusing on a gasket arrangement portion of the grounding structure according to the first embodiment. 
           [0021]    [ FIGS. 5 ] are views showing procedure of forming the grounding structure by the gasket according to the first embodiment. 
           [0022]    [ FIGS. 6 ] are views showing arrangement of a grounding structure by a gasket according to a second embodiment. 
           [0023]    [ FIGS. 7 ] are views showing a gasket arrangement portion according to a third embodiment. 
           [0024]    [ FIGS. 8 ] are views showing a gasket arrangement portion according to a fourth embodiment. 
           [0025]    [ FIG. 9 ] is a view showing a gasket arrangement portion according to a fifth embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS  
       [0026]    Next, description will be specifically given for forms for implementing the present invention (hereinafter, simply referred to as “embodiments”) with reference to drawings. 
       First Embodiment 
       [0027]      FIG. 2  is an exploded perspective view of a liquid crystal television  10  according to the present embodiment, which is schematically expressed so that a front side and a rear side are arranged in a lower side of the figure and an upper side of the figure, respectively. 
         [0028]    As shown in the figure, a backlight unit  30  is arranged so as to face a rear side (upper side in the figure) of a display panel  12 . Moreover, a front cabinet  11  is arranged in a forward side (lower side in the figure) of the display panel  12 . 
         [0029]    The backlight unit  30  is a so-called direct-type backlight, and a plurality of LEDs are arranged on a frontward side of a metal plate member thereof as a light source. Further, on a rear side of the backlight unit  30 , a resin-made backlight cabinet  20  is arranged so as to face thereto. Then, a main PWB  50  is arranged so as to face thereto in a predetermined region on a further rear side thereof. Furthermore, on a rear side of the backlight cabinet  20  to which the main PWB  50  is attached, a rear cabinet  13  is arranged so as to face thereto. 
         [0030]    A gasket arrangement portion  40  by which the backlight cabinet  20  is communicated back and forth is provided in the backlight cabinet  20 , and description thereof will be given below in detail. A gasket  90  having a predetermined size is arranged in this gasket arrangement portion  40 , and a predetermined rectangular region  35  of the metal plate member of the backlight unit  30  and a predetermined grounding circuit region (ground pattern) of the main PWB  50  are electrically connected. 
         [0031]    A perspective view of  FIG. 3  is shown by focusing on the backlight cabinet  20  and the main PWB  50 . 
         [0032]    As described above, the main PWB  50  is arranged on and fixed to the rear surface of the backlight cabinet  20 . At this time, the main PWB  50  is grounded with respect to the backlight unit  30  by the gasket  90 . Various LSIs for processing, input/output terminals, and the like are arranged on a top surface of a back side (upper side of the figure) of the main PWB  50 . 
         [0033]    Description will hereinafter be given for a structure of grounding with reference to  FIGS. 4  and  FIGS. 5 . Here,  FIGS. 4  are views focusing on the gasket arrangement portion of the grounding structure. Moreover,  FIGS. 5  are views showing procedure of forming the grounding structure by the gasket, in which particularly  FIG. 5C  corresponds to a sectional view taken along A-A of  FIG. 3 . 
         [0034]    As illustrated, the gasket arrangement portion  40  for arranging the gasket  90  therein is formed on the backlight cabinet  20 . Note that, the gasket  90  is a regular hexahedron having a size of 15 mm×15 mm×15 mm and has cushioning property which allows being pressed down by a fixed amount. 
         [0035]    The gasket arrangement portion  40  is formed by a gasket through opening  42  which is a quadrilateral and a wall portion  44  surrounding four sides of this gasket through opening  42 . Note that, from a viewpoint of consideration of falling of the gasket  90  due to aged deterioration or the like, the wall portion  44  only needs to be formed mainly around a region corresponding to a lower side of the liquid crystal television  10  when being used in a standing manner, and does not need to be formed in a region corresponding to an upper side thereof. However, when considering a case where the gasket  90  is shifted and deformed in accordance with movement of the main PWB  50  or the like, it is preferable to be formed also in the region on the upper side. Moreover, it is not necessary to be formed so as to have a complete wall surface, and a plurality of pin-shaped structures may be used. 
         [0036]    Here, the gasket through opening  42  has a size of 16 mm×16 mm. Accordingly, in a state where the gasket  90  is arranged, a gap of 0.5 mm is formed in upper and lower, and right and left sides between the gasket  90  and the gasket through opening  42 . 
         [0037]    The wall portion  44  is formed in a convex shape having a height of 3.5 mm so as to surround the gasket through opening  42  and so as to have a predetermined width on the rear side. Note that, a thickness of a plate part of the backlight cabinet  20  is 3.0 mm. Moreover, in a state where the liquid crystal television  10  has been properly assembled, a distance between the backlight unit  30  (metal plate member  32 ) and the backlight cabinet  20  is 2.55 mm. Furthermore, a distance between a tip portion of the wall portion  44  and the main PWB  50  is 2.5 mm. That is, a distance between the metal plate member  32  on the rear side of the backlight unit  30  and the main PWB  50  is 11.55 mm, and the gasket  90  is fixed in a state of being crushed by 3.45 mm. Note that, on a frontward side of the main PWB  50  (a lower side in the figure and a side of a surface facing the backlight cabinet  20 ), the rectangular region  35  of laterally 18 mm×longitudinally 15 mm is secured as a grounding region in a region to which the gasket  90  is fixed. 
         [0038]    Here, description will be given for procedure of arranging the grounding structure by the gasket. 
         [0039]    First, as shown in  FIG. 5A , in a state where the backlight cabinet  20  is properly arranged on the rear side of the backlight unit  30 , the gasket  90  is inserted into the gasket arrangement portion  40  and arranged on the predetermined region  35  for grounding of the backlight unit  30 . At this time, the gasket  90  is keeping an original form thereof. 
         [0040]    Subsequently, as shown in  FIG. 5B , the main PWB  50  is arranged from above the gasket  90 , that is, from the rear side. At this time, the distance between the main PWB and the backlight cabinet  20  is set as 2.5 mm, as described with  FIG. 4D . Accordingly, the main PWB  50  is fixed to the backlight cabinet  20  as shown in  FIG. 5C , and thereby the gasket  90  is pressed down by a predetermined amount to be fixed. A length of the gasket  90  which is projecting from an upper end of the wall portion  44  of the gasket arrangement portion  40  changes into 5.5 mm from 8.95 mm before being crushed. 
         [0041]    As above, according to the present embodiment, mechanical strength of fixation of the gasket is secured. That is, a width and an area which face side surfaces of the gasket  90  increase. Thus, it is possible to control deformation of a shape of the gasket  90  at a time of attaching work of the gasket  90 . Accordingly, suppression of shift due to vibrations or the like and positioning at the time of attaching work of the gasket  90  become easy. Moreover, stable contact and conduction of the main PWB  50  and the metal plate member (backlight unit  30 ) on which the LEDs are arranged are secured, thus making it possible to suppress worsening of unnecessary radiation. 
       Second Embodiment 
       [0042]      FIGS. 6  are views showing the gasket arrangement portion  40  according to a second embodiment. For example, as shown in  FIG. 6A , a claw-shaped locking structure  46  may be formed on an inner surface of the wall portion  44 . The fixation of the gasket  90  becomes even firmer. The locking structure  46  may be formed throughout a whole circumference of the inner surface, or may be formed only in a partial region. Moreover, a size of the locking structure  46  is set in consideration of balance of workability at a time of arranging the gasket  90 , a deformation amount at a time of being crushed, and fixing force, and is, for example, about 0.5 mm which corresponds to the aforementioned gap between the gasket  90  and the gasket arrangement portion  40 . Moreover, as shown in  FIG. 6B , holes  48  may be provided at two sites on the wall portion  44 , which face each other, and a bar for fixation  49  may be attached to these holes  48  so as to stick and pass through the gasket  90 . Note that, not one but a plurality of the bars for fixation  49  passing through the gasket  90  may be provided, and a configuration of not passing through may be used. 
         [0043]    In addition, the height of the wall portion  44  of the gasket arrangement portion  40  may be lowered only on a surface of a cushioning part of the gasket  90 , which is not particularly illustrated. By creating an escape place for the cushion of the crushed gasket  90 , when being deformed, it is possible to prevent the gasket  90  from being in contact with other than the ground pattern. 
       Third Embodiment 
       [0044]      FIGS. 7  are views showing gasket arrangement portions  240  and  340  according to a third embodiment, which are views corresponding to  FIG. 4B . 
         [0045]    The gasket arrangement portion  240  shown in  FIG. 7A  is provided with first to fourth protruding portions  244   a  to  244   d  which are formed in four corners of the gasket through opening  42  as a configuration corresponding to the above-described wall portion  44  which surrounds a circumference of the gasket through opening  42 . The first to fourth protruding portions  244   a  to  244   d  have an L-shaped rib protrusion structure in a top view. 
         [0046]    The gasket arrangement portion  340  shown in  FIG. 7B  is provided with first to fourth wall portions  344   a  to  344   d  which have a plate shape (rib shape) in a vicinity of the four sides of the gasket through opening  42  as a configuration corresponding to the above-described wall portion  44  which surrounds the circumference of the gasket through opening  42 . Contrary to the configuration of  FIG. 7A , provided is the configuration that the four corners of the above-described wall portion  44  are removed. 
         [0047]    With these structures, in a case where the gasket is crushed and deformed, the crushed part fits into spaces at four sites in which the first to fourth protruding portions  244   a  to  244   d  or the first to fourth wall portions  344   a  to  344   d  are not formed, so that a position maintaining function of the gasket  90  excellently acts with respect to vibrations in every direction. 
       Fourth Embodiment 
       [0048]      FIGS. 8  are sectional side views showing a gasket arrangement portion  440  according to a fourth embodiment, which correspond to  FIGS. 5 . In the gasket arrangement portion  440 , a wall portion  444  which projects upward and downward, that is, projects to both sides of the main PWB  50  and the backlight unit  30  so as to surround a gasket through opening  442  is formed. Then, in an inner wall surface of the wall portion  444 , the gasket through opening  442  is formed so as to widen toward the side of the backlight unit  30 . That is, the gasket through opening  442  is to be a truncated quadrangular pyramid. A size of an upper side of the gasket through opening  442  is approximately same as that of an external form of the gasket  90 . 
         [0049]    Like in  FIG. 8A , the gasket  90  is inserted into the gasket through opening  442  from above, which comes to be in a state of  FIG. 8B . In the state of  FIG. 8B , a predetermined space X is formed between the wall portion  444  and the gasket  90 . Then, like in  FIG. 8C , when the main PWB is attached and the gasket  90  is crushed and deformed, the deformed part is to expand in the space X between the wall portion  444  and the gasket  90 . As a result thereof, the deformed part is not to protrude to the side of the main PWB  50 . Accordingly, the gasket  90  does not exert a bad influence with respect to parts or wires mounted on the main PWB  50 . 
       Fifth Embodiment 
       [0050]      FIG. 9  is a sectional side view showing a gasket arrangement portion  540  according to a fifth embodiment. This gasket arrangement portion  540  has an upper-side wall portion  544   a  which is formed so as to surround an upper side of a gasket through opening  542 , and first lower-side wall portions  544   b  and second lower-side wall portions  544   c  which are formed in a lower side thereof. The upper-side wall portion  544   a  has a structure same as that of the wall portion  40  shown in  FIG. 6A , and a claw-shaped locking structure  546  is formed in an upper side of an inner surface of the upper-side wall portion  544   a.  In the gasket  90  which is locked by the locking structure  546 , a predetermined notch or a concave shape for determining a locking position is formed. 
         [0051]    Two wall portions in a far side and a near side in the figure (not shown) correspond to the first lower-side wall portions  544   b.  These first lower-side wall portions  544   b  are formed in a rib shape extending perpendicularly in a lower direction only by a predetermined length. Two right and left wall portions correspond to the second lower-side wall portions  544   c  in the figure. These second lower-side wall portions  544   c  have a structure of widening toward an external direction. 
         [0052]    With these structures, when the gasket  90  attached to the gasket arrangement portion  540  is pressed down and deformed, the deformed part is guided by the second lower-side wall portions  544   c  widening toward the external direction. 
         [0053]    As above, description has been given for the present invention based on the embodiments. These embodiments are only exemplary and those skilled in the art could understand that, by combining each of the components thereof, etc., various modifications are possible, and such modifications are also within the scope of the present invention. 
       Reference Signs List 
       [0000]    
       
           10  liquid crystal television 
           11  front cabinet 
           12  display panel 
           13  rear cabinet 
           20  backlight cabinet 
           30  backlight unit 
           32  metal plate member 
           35  region 
           40 ,  240 ,  340 ,  440 ,  540  gasket arrangement portion 
           42 ,  442 ,  542  gasket through opening 
           44 ,  444  wall portion 
           46 ,  546  locking structure 
           48  hole 
           49  bar for fixation 
           50  main PWB 
           90  gasket 
           244   a  to  244   d  first to fourth protruding portion 
           344   a  to  344   d  first to fourth wall portion 
           544   a  upper-side wall portion 
           544   b  first lower-side wall portion 
           544   c  second lower-side wall portion