Abstract:
The present invention provides a simply usable shield cover capable of enhancing the mechanical strength of a set even if a display device is decreased in thickness. In a video display apparatus including a base chassis on a front surface of which a displaying member is arranged and on a back surface of which a unit for driving and controlling the display device is arranged, and a plurality of frames arranged on the back surface of the base chassis in parallel with each other, a shield cover is attached to the plurality of frames to extend over those to form a crosslink structure.

Description:
INCORPORATION BY REFERENCE 
       [0001]    The present application claims priority from Japanese application No. 2008-247089 filed on Sep. 26, 2008, the content of which is hereby incorporated by reference into this application. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the invention 
         [0003]    The present invention relates to a video display apparatus using a flat panel such as a liquid crystal panel as a display panel. 
         [0004]    2. Description of related art 
         [0005]    A video display apparatus such as a liquid crystal television and a plasma television tends to decrease in thickness year by year. However, if the decrease of thickness is intended, a depth space becomes small, which makes it difficult to obtain a sufficient strength of the entire apparatus. As a conventional technique for solving this problem to ensure the strength while keeping the depth of the video display apparatus thin, there is known the one described in JP-A-2006-39062, for example. 
         [0006]    JP-A-2006-39062 discloses to arrange a main frame as a reinforced member on a back side of a panel module and fix a reinforced frame to the main frame to increase the strength of the main frame, so that the strength of the entire video display apparatus is ensured while decreasing the thickness thereof. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In recent years, a video display apparatus is required to be not only reduced in thickness, but also increased in size. In order to achieve the reduction in thickness and the increase in size, it becomes necessary to ensure not only the strength against a bending load in a vertical direction of the entire video display apparatus, but also the strength against a torsion load thereof. 
         [0008]    The technique described in JP-A-2006-39062 increases the strength by fixing the reinforced frame to the two main frames arranged on the back side of the panel module as reinforcing members. While it is effective for a bending load in a vertical direction of the entire video display apparatus, the technique does not consider a torsion load at all. 
         [0009]    The present invention is made in view of the above problem, and provides a technique for enabling the reduction in thickness and the increase in size while increasing the strength against a torsion load of the entire video display apparatus. 
         [0010]    The present invention is characterized in that at least two frames are provided on a back surface of a base chassis on a front surface of which a display panel is arranged, and a plate-like shield cover is fixed to the two frames across those. By arranging a substrate for driving and controlling the display panel between the two frames to which the shield cover is fixed, the substrate may be covered with the shield cover. 
         [0011]    According to the above configuration, the strength against a bending load and a torsion load of the entire video display apparatus can be increased by attaching the shield cover to at least two frames among the frames arranged on the back surface of the base chassis to three-dimensionally support the display apparatus by the base chassis, the frames and the reinforcing members, as described above. 
         [0012]    According to the present invention, it becomes possible to decrease in thickness and increase in size while enhancing the stiffness of the video display apparatus. 
         [0013]    Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0014]      FIG. 1  is a front perspective view of a video display apparatus to which the present invention is applied; 
           [0015]      FIG. 2  is an exploded perspective view of a liquid crystal panel module according to the present embodiment; 
           [0016]      FIG. 3A  is a view showing a base chassis and a panel frame according to the present embodiment; 
           [0017]      FIG. 3B  is a view showing a screw fixation portion of the base chassis and the panel frame according to the present embodiment; 
           [0018]      FIG. 4  is a view showing a screw fixation portion of the panel frame and a panel supporting member according to the present embodiment; 
           [0019]      FIG. 5  is a view showing a screw fixation portion of the panel module, a frame and a shield according to the present embodiment; 
           [0020]      FIG. 6  is a cross sectional view taken along line B-B of  FIG. 5  in a state where the panel module, the frame and the shield cover are assembled; 
           [0021]      FIG. 7  is a cross sectional view showing one example of a heat dissipating structure utilizing a shield cover according to the present embodiment; 
           [0022]      FIG. 8  is a view showing a state of a back surface in which frames  162  and a shield cover  163  are attached to a base chassis  122  according to the present embodiment; and 
           [0023]      FIG. 9  is a view showing a back surface of the video display apparatus according to the present embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Hereinafter, the embodiment of the video display apparatus according to the present invention will be described with reference to the drawings taking a liquid crystal color television using a side-edge type LED backlight liquid crystal panel module for example. 
         [0025]      FIG. 1  is a perspective view of a video display apparatus according to the present invention. The video display apparatus  100  includes a panel module  120  and a front bezel  110  which is a housing surrounding the periphery thereof. In the video display apparatus  100 , a display screen  121  provided by the panel module  120  appears from a front opening of the front bezel  110  and stands alone by means of a stand  150 . 
         [0026]    For the sake of convenience in description, upper, lower, left, right, front and back are defined with respect to the display screen  121  of the video display apparatus  100 . That is, when a user viewing the video display apparatus  100  opposes the display screen  121 , the side of the display screen  121  near the user is defined as “front surface”, the far side is defined as “back surface”, the horizontal right side of the video display apparatus  100  viewed from the user is defined as “right”, and the horizontal left side thereof is defined as “left”. Further, the vertical upper side of the video display apparatus  100  viewed from the user is defined as “upper”, and the vertical lower side thereof is defined as “lower”. A back cover (not shown) is arranged at the back side of the panel module  120 . 
         [0027]    Referring to  FIGS. 2 to 4 , there is described one example of a configuration on the front side of a base chassis  122  of the panel module  120  according to the present embodiment, and an attachment structure of various elements on the front side. 
         [0028]      FIG. 2  is an exploded perspective view of the panel module  120  according to the present embodiment. The panel module  120  according to the present embodiment includes the base chassis  122 , a panel frame  123 , an optical sheet group  125  including a plurality of optical sheets, a first panel supporting member  126 , a liquid crystal panel  127  and a second panel supporting member  128 . The liquid crystal panel  127  is configured such that a liquid crystal is sandwiched between two substrates, and has a function as an optical shutter which turns on and off a liquid crystal of each pixel based on an inputted video signal to control the transmission/shielding of light incident from the optical sheet group  125 . 
         [0029]    As illustrated in  FIG. 2 , the optical sheet group  125  and the liquid crystal panel  127  are fixed by the panel frame  123 , the first panel supporting member  126  and the second panel supporting member  128  to be arranged on the front side of the base chassis  122 . The fixing is described in detail below with reference to  FIGS. 3 and 4 . 
         [0030]      FIG. 3  is an exploded view illustrating a configuration concerning attachment of the panel frame  123  and the base chassis  122 . The base chassis  122  and the panel frame  123  are a metallic member such as stainless steel, iron and aluminum for example, and are preferably the same material, but may be different materials as long as the materials are metal. 
         [0031]    The panel frame  123  is composed of four bar-like members  123   a  to  123   d , made a square frame shape as illustrated in the figure, and fixed to the base chassis  122  by a plurality of first panel fixing screws  142 . Light source modules  124  which are configured or arranged so that light travels inward are mounted on the right and the left panel frames  123   a  and  123   c . The light source module  124  is composed of a plurality of light emitting diodes (LED) and is formed such that a plurality of groups of, for example, red, blue and green LEDs are arranged along the longitudinal direction of the panel frame  123 . A group of LEDs is not always formed of a red, blue and green one, but a white diode which emits white light in itself may be used. Alternatively, a configuration where the white light is emitted by two diodes different in color (for example, yellow and blue) may be used. 
         [0032]    Heat generated by the light source module  124  is thermally transferred from the panel frame  123  to the base chassis  122  and released at the base chassis  122 . 
         [0033]      FIG. 3B  is an enlarged view illustrating a joint portion of the right panel frame  123   a  and the upper panel frame  123   b . As illustrated in the figure, the right panel frame  123   a  and the upper panel frame  123   b  are provided with step portions respectively, and crossed with each other at the step portions to be fixed. The other three portions are similarly provided with step portions and crossed with each other at the step portions to be fixed. 
         [0034]      FIG. 4  is an exploded perspective view illustrating a configuration relating to attachment of the base chassis  122 , the optical sheet group  125  and the liquid crystal panel  127 . 
         [0035]    As illustrated in  FIG. 4 , the optical sheet group  125  including a plurality of optical sheets is arranged on the front side of the base chassis  122  to which the above described panel frame  123  is fixed. The optical sheet group  125  is held by the base chassis  122  on its back side and the first panel supporting member  126  on its front side to be sandwiched therebetween. The liquid crystal panel  127  is held and sandwiched between the first and the second panel supporting members  126  and  128 . As illustrated in the figure, the first and the second panel supporting members  126  and  128  are fixed to the panel frame  123  by a plurality of second panel fixing screws  143 . Among the screws, four panel fixing screws  143   a  located at the corner portions simultaneously fix the step portions which are joint portions of the four panel frames  123   a  to  123   d . The optical sheet group  125  is made of a light guide plate and a diffusion sheet, and has a function to irradiate the front side with light of the light source module  124  incident from a side of the optical sheet group  125  so as to uniform its luminance in a plane (referred to as backlight). 
         [0036]    The first panel supporting member  126  is formed of a resin (for example, polycarbonate in the present embodiment). A rubber sheet (not shown) is pasted on a contact portion between the first panel supporting member  126  and the liquid crystal panel  127 . The second panel supporting member  128  is made of a metallic member such as stainless steel, iron and aluminum, for example, as described above, since it is a member receiving the panel fixing screws  143 . Incidentally, as is the case with the first panel supporting member, a rubber sheet (not shown) is pasted on a contact portion of the second panel supporting member  128  and the liquid crystal panel  127 . The rubber sheets prevent the liquid crystal panel  127  from being subjected to a load due to fixation of the screws, and function as a buffer member at the same time. 
         [0037]    As described above, the panel frame  123  and the panel supporting members  126  and  128  are stacked on the four peripheral sides of the base chassis  122  in a thickness direction and rigidly fixed by the panel fixing screws  142 ,  143 , so that the stiffness of the panel module  120  itself is ensured. 
         [0038]    Next, referring to  FIGS. 5 to 8 , there is described one example of a configuration on the back side of the base chassis  122  of the panel module  120  according to the present embodiment, and an attachment structure of various elements on the front side. 
         [0039]      FIG. 5  is an exploded perspective view illustrating an attachment structure of a substrate and a reinforced structure on the back side of the panel module  120 . 
         [0040]    On the back side of the panel module  120 , there are arranged a substrate group  161  such as a power supply substrate and a control substrate adapted to drive and/or control the liquid crystal panel  127  and the light source module  124  and a signal processing substrate. The substrate group  161  is fixed to the base chassis  122  constituting the back surface of the panel module  120 , for example, by a screw (not shown).  FIG. 6  is a cross sectional view taken along line B-B of  FIG. 5  showing a state where the panel module  120 , the frame  162  and a shield cover  163  are assembled. 
         [0041]    The two frames  162  are a bar-like reinforcing member in which a metallic plate, for example, made of stainless steel, iron and aluminum is bent in a longitudinal direction into a U-shape and extends in a vertical direction (or in the upper and the lower direction) of the video display apparatus  100 . The two frames  162  are assembled in parallel to each other by frame fixing screws  144  on the back surface of the base chassis  122 . The frame fixing screws  144  reach the upper panel frame  123   b  and the lower panel frame  123   d  which are a reinforcing member of the panel module  120  and form a rigid body together with the panel module  120 . Between the two frames  162 , there are arranged the substrate group  161  such as a power supply circuit substrate, a control circuit substrate and a signal processing circuit substrate. In the present embodiment, all the substrate group  161  is disposed between the two frames  162 , but it is not limited thereto, while at least one of the substrates may be arranged between the two frames  162 . For example, the power supply circuit with a high heating value and/or the signal processing circuit radiating an electromagnetic wave may be arranged between the two frames  162  and an LED driver (not shown) for driving an LED as a light source may be arranged outside the frames  162  (on the left and right end sides of the of the video display apparatus  100 ). In the present embodiment, although two frames  162  are used, three or four frames may be used. The number of the frames  162  may be properly selected according to the size (the number of inches) of the liquid crystal panel  127  or the required strength. 
         [0042]    The shield cover  163  is attached from the back side so as to cover the substrate group  161  arranged between the two frames  162  and to extend between the two frames  162 . Such an attachment is performed, for example, by fixing shield fixing screws  145  to a metallic stud boss  165  fixed to the base chassis  122  by press fit or caulking as illustrated in  FIG. 6 . A shield fixing screw  145   a  at the center of the shield cover  163  fixes the shield cover  163  to the stud boss  165 . Shield fixing screws  145   b  at the left and right sides of the shield cover  163  fix the shield cover  163  and the frames  162  to the stud bosses  165 . Thus, the shield cover  163  becomes a bridge structure of the two frames  162 . That is, the two frames  162  are fixed to the upper and lower panel frames  123   b  and  123   d  by the frame fixing screws  144  and to the stud boss  165  provided on the base chassis  122  by a shield fixing screw  145   d , thereby securing the strength against a bending load. 
         [0043]    Further, the shield cover  163  is two-dimensionally fixed by the shield fixing screws  145  to the base chassis  122  to ensure the strength of the shield cover  163  and the panel frame  123  against a torsion load. At the same time, by fixing the shield cover  163  to the two frames  162  so as to become the crosslink structure, the strength against a torsion load is further improved. 
         [0044]    As described above, the one shield cover  163  is fixed to cover at least one substrate  161  and electrically grounded by the shield fixing screws  145 . Thus, according to this configuration, since it is possible to completely cover an electronic component which is mounted on the substrate group  161  and may cause undesired radiation and a leakage path (such as a cable and a connector terminal connected between substrates), it is possible to effectively prevent electromagnetic jamming from leaking outside and decrease the EMI to another device. 
         [0045]    That is to say, the shield cover  163  according to the present embodiment improves the strength against a torsion load of the video display apparatus  100  and prevents the undesired radiation from leaking outside. 
         [0046]    Incidentally, insulating sheets (not shown) are attached between the base chassis  122  and the substrate group  161  mounted thereon, and between the substrate group  161  and the shield cover  163  to avoid an electrical contact. 
         [0047]    Further, it is possible to effectively cool the substrate group  161  using the shield cover  163 . Hereinafter, the shield cover  163  will be described with reference to  FIG. 7  in connection with a configuration relating to heat dissipation of the substrate group  161 . 
         [0048]      FIG. 7  is a cross sectional view illustrating one example of a heat dissipation configuration of a heating part  171  mounted on the substrate group  161  by means of the shield cover  163 . In  FIG. 7 , the components given the same reference numeral as the already described components have the same configuration and function as those, and thus a duplicated description thereof is omitted. 
         [0049]    The substrate group  161  is fixed to the back surface of the panel module  120  through an insulating sheet  164 . An appropriate space is formed between the panel module  120  and the insulating sheet  164 , and the substrate group  161  to provide air insulation so that heat of the substrate group  161  is not transferred to the panel module  120  or heat of the panel module  120  is not transferred to the substrate group  161 . The heating part  171  (for example, a transformer of the power supply circuit, a main microcomputer (CPU) of the signal processing substrate, a decoder circuit or the like) mounted on the substrate group  161  is brought into contact with the shield cover  163  through a thermal conductive member  172  made of a thermal conductive raw material, for example, silicon rubber. For this reason, the heat generated from the heating part  171  is transferred by the thermal conductive member  172  to the shield cover  163  and released from the shield cover  163 . A back cover  130  as a housing for the video display apparatus  100  is arranged on the back side of the shield cover  163 . The back cover  130  may be brought into contact with the shield cover  163  through, for example, a thermal conductive member, or may not be brought into contact therewith by providing a gap therebetween. 
         [0050]    When using the shield cover  163  having the structure of widely covering a plurality of the substrate groups  161  like the present embodiment, the area of the shield cover  163  becomes greater than the case where the shield cover  163  is used for each, single substrate, so that expansion of the cooling area is anticipated. Consequently, the cooling effect and the thermal diffusion effect are increased so that cooling of the heating part  171 , and prevention of local raise in temperature of the substrate group  161  become possible. 
         [0051]    That is, the shield cover  163  according to the present embodiment can have a function of ensuring the strength, a function of decreasing the leakage of electromagnetic jamming to the outside and a function of cooling the heating part  171 . 
         [0052]      FIG. 8  is a perspective view illustrating the back surface in which the bar-like frames  162  and the shield cover  163  are fixed to the base chassis  122  and, a configuration relating to attachment of the front bezel  110  and the stand  150 . In the figure, the back cover  130  is removed. 
         [0053]    As illustrated in  FIG. 8 , the front bezel  110  is fixed to the panel module  120  along the outer peripheral thereof by bezel fixing screws  146 . The stand  150  is fixed to the two frames  162  by screws (not shown). By this configuration, a load applied to the stand  150  based on the deadweight of the video display apparatus  100  is distributed to the two bar-like frames  162  as reinforcing members and the shield cover  163  fixed to the frame  162  as a reinforced member, and therefore such a load is prevented from being applied directly to the liquid crystal panel  127 . Thus, according to the present embodiment, it is possible to further increase the strength against a load applied to the video display apparatus when the video display apparatus  100  is placed stationary by using the stand  150 . Such an effect can be similarly provided in the case where the video display apparatus  100  is placed and hung on a wall. 
         [0054]    When the video display apparatus is placed and hung on a wall, the video display apparatus  100  is hung on the wall by, for example, removing the stand  150  from the two frames  162 , attaching a wall-hang metal fitting (not shown) to the two frames  162  instead of the stand, and hanging the wall-hang metal fitting on the wall. Also in this case, although a load based on the deadweight of the video display apparatus  100  is applied to the video display apparatus  100  through the wall-hang metal fitting, such a load is distributed to the two frames  162  and the shield cover  163 , and therefore such a load is prevented from being applied directly to the liquid crystal panel  127 . Thus, according to the present embodiment, it is possible to further increase the strength against a load applied to the video display apparatus  100  when the video display apparatus  100  is placed and hung on a wall. 
         [0055]    Next, the appearance of the video display apparatus  100  viewed from the back side thereof and the fixing structure of the back cover  130  will be described with reference to  FIG. 9 . 
         [0056]    As illustrated in  FIG. 9 , the back cover  130  is similarly fixed to the front bezel  110  along the outer peripheral thereof by cover fixing screws  141 . In this configuration, cover fixing screws  141   b  of the back cover  130  other than cover fixing screws  141   a  are fixed also to the panel frame  123  through the base chassis  122 . This makes appearance parts to form a box shape, which has a function of reinforcing the panel module  120 . 
         [0057]    In this embodiment, a protruding portion  131  which protrudes toward the back side of the video display apparatus  100  with respect to another portion is provided on a portion of the back cover  130  which corresponds to the two frames  162  and the shield cover  163  in position. An air inlet  132  for letting air flow into a space inside the protruding portion  131  is provided below the protruding portion  131 . An air outlet  133  which discharges air inside the protruding portion  131  is provided on a portion above the protruding portion  131 . 
         [0058]    By forming the portion of the back cover  130  corresponding to the two frames  162  and the shield cover  163  in position as the protruding portion  131  which protrudes toward the back side of the video display apparatus  100 , the cooling area including the substrate group  161  having the heating part  171  (that is, the area where the space is in contact with the air outside the video display apparatus  100 ) becomes increased, so that cooling of the substrate group  161  is performed more preferably. Further, if the air inlet  132  and the air outlet  133  are provided below and above the protruding portion  131 , respectively, it is possible to make air flow into the space in the protruding portion  131  (see  FIG. 7 ) so as to flow the air through the space between the base chassis  122  and the substrate group  161  and the space between the substrate group  161  and the shield cover  163 . According to such a configuration, therefore, the substrate group  161  lying in the protruding portion  131  can be more preferably cooled. 
         [0059]    According to the present embodiment, each element of a panel module portion, an internal mechanism portion and an appearance portion has a structure for increasing stiffness. Further, the frame fixing screws  144  and shield fixing screws  145  firmly fix between “the panel module portion and the internal mechanism portion”, and the cover fixing screws  141  firmly fix between “the internal mechanism portion and the appearance portion”, and between “the panel module portion and the appearance portion”. In other words, since the reinforced structures of respective elements are rigidly fixed together by screws, respective structures act on each other synergistically, so that the flexural rigidity and the stiffness in torsion of the entire video display apparatus  100  are reinforced, and the video display apparatus can be decreased in thickness. 
         [0060]    Although the present embodiment has described above with respect to the side-edge type LED backlight liquid crystal display, the present embodiment is applicable to various panel modules irrespective of a backlight type. In addition, the present embodiment is similarly applicable not only to a liquid crystal panel, but also to a plasma display panel (PDP). 
         [0061]    The present invention is not limited to the embodiments described above and illustrated in the figures, but various modifications may be made without departing from the spirit thereof.