Patent Publication Number: US-2010124046-A1

Title: Lighting device for display device, display device, and television receiver apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a lighting device for a display device, a display device, and a television receiver apparatus. 
     BACKGROUND ART 
     A liquid crystal display device includes a liquid crystal panel, and a backlight provided on a back surface side of the liquid crystal panel. The backlight includes a chassis housing a light source such as a cold cathode tube and having an opening surface on a light emitting side, and an optical member provided in an opening portion of the chassis and having a function of converting a light emitted from the light source into a uniform planar light. 
     The optical member includes a diffuser plate containing a plurality of diffusing particles dispersed in a transparent base material having a predetermined thickness, and an outer peripheral end portion thereof is received and supported by a catch in the chassis. Meanwhile, a more inner portion than the outer peripheral end portion of the diffuser plate is supported by a support component mounted to the chassis. 
     A known example of such a support component is described in Patent Document 1. This support component includes a support pin protruding toward a diffuser plate, and a tip portion of the support pin abuts at a point against a more inner portion than an outer peripheral end portion of the diffuser plate to support the diffuser plate. A plurality of support pins are arranged so as to support the diffuser plate in different positions in a plane direction. 
     Meanwhile, an example of a support component using a surface emitting flat lamp as a light source is described in Patent Document 2. This support component includes a linear support portion having a top extending in one direction, and linearly supports a diffuser plate.
     [Patent Document 1] Japanese Patent Laid-Open No. 2004-219838   [Patent Document 2] Japanese Patent Laid-Open No. 2005-203164   

     Problems to be Solved by the Invention 
     The above described diffuser plate is sometimes warped into an arc shape toward a light source as the light source is lit and a temperature in the chassis is increased. However, since the support pins described in Patent Document 1 all have the same height, the diffuser plate may be bent into a corrugated shape toward the light source with a support position by each support pin as a fulcrum. Then, the corrugated bent portion may significantly reduce display quality of a liquid crystal display device. 
     Meanwhile, the support portion described in Patent Document 2 linearly supports the diffuser plate, and the diffuser plate is hard to be bent as described above in an extending direction of the support portion. However, since the support portion has a fixed height over the entire length, the diffuser plate to be warped and deformed toward the light source may press the support portion to cause a problem such as a groan. 
     DISCLOSURE OF THE INVENTION 
     The present invention is achieved in view of the above described circumstances and has an object to properly support an optical member. 
     Means for Solving the Problems 
     The present invention includes: a chassis housing a light source that applies a light to a display panel that displays an image; a planar optical member provided on an emission side of the light emitted from the light source; and a support portion that is mounted to the chassis and can support the optical member from the side of the light source, wherein a plurality of the support portions have point shapes with respect to a surface of the optical member, are arranged in the surface in a distributed manner, and include a lower support portion and a higher support portion that support the optical member at different heights, and the lower support portion is placed on a middle side of the optical member and the higher support portion is placed on an end side of the optical member. 
     If the optical member is warped and deformed toward the light source as the light source is lit or the like, the optical member is shaped to become lower from the end side toward the middle side. At this time, the plurality of support portions having the point shapes with respect to the surface of the optical member and arranged in the surface in a distributed manner include the lower support portion and the higher support portion that support the optical member at different heights, and the middle side of the optical member is supported by the lower support portion and the end side is supported by the higher support portion, thereby allowing the optical member to be supported in a position matching the warped shape. Thus, the optical member can be supported in a state where the optical member can be warped and deformed and the optical member is hard to be bent. 
     The following configurations are preferable as illustrative aspects of the present invention. 
     (1) The support portions are configured to support the optical member at gradually increasing heights from the middle side toward the end side of the optical member. This allows the warped and deformed optical member to be supported at a more proper height. 
     (2) The support portions are arranged in a zigzag manner. Thus, the support portions can be efficiently distributed in the surface of the optical member, thereby allowing the optical member to be more properly supported. 
     (3) When the optical member has a rectangular shape, the support portions are linearly arranged in a short side direction of the optical member. Thus, the optical member can be satisfactorily supported by the support portions linearly arranged in the short side direction thereof. 
     (4) When the optical member has a rectangular shape, the support portions are linearly arranged in a long side direction of the optical member. Thus, the optical member can be satisfactorily supported by the support portions linearly arranged in the long side direction. 
     (5) Among the support portions, a support portion placed closest to an end of the optical member and a support portion adjacent thereto support the optical member at the same height. Thus, the number of support portions having the same support height is increased to reduce production costs. The optical member tends to be less warped on the end side than on the middle side, and thus the optical member can be satisfactorily supported even if the support portions having the same support height are provided adjacent to each other on the end side of the optical member. 
     (6) The support portions are tapered. This can avoid the support portions from blocking the light emitted from the light source. 
     (7) The support portions have surfaces with white base color. Thus, the light emitted from the light source is reflected by the surfaces of the support portions, thereby increasing use efficiency of the light. 
     (8) The support portion includes a mounting plate mounted to the chassis, and a light source gripping portion that can grip the light source is provided on the mounting plate in a lateral position of the support portion. This allows the support portion to also have a function of gripping the light source. 
     (9) The optical member is subjected to previous warping so as to be warped and deformed toward the light source as the light source is lit. This prevents the optical member from being warped and deformed in a reverse direction, thereby allowing the support portion to reliably support the optical member. 
     (10) The previous warping includes heating treatment of a surface on the side opposite to the light source of a base material of the optical member. This allows previous warping without adding another member to the optical member. 
     (11) The previous warping includes forming a previous warping layer constituted by beads on one of the surface on the side of the light source and the surface on the opposite side of the base material of the optical member by coating, and one of the previous warping layer and the base material placed on the side of the light source has a linear expansion coefficient higher than that of the other placed on the opposite side. Thus, when the light source is lit, the previous warping layer constituted by the beads causes the optical member to be reliably warped and deformed toward the light source. 
     (12) The previous warping includes attaching a previous warping layer formed of a sheet material to one of the surface on the side of the light source and the surface on the opposite side of the base material of the optical member, and one of the previous warping layer and the base material placed on the side of the light source has a linear expansion coefficient higher than that of the other placed on the opposite side. Thus, when the light source is lit, the previous warping layer formed of the sheet material causes the optical member to be reliably warped and deformed toward the light source. 
     Advantage of the Invention 
     According to the present invention, the optical member can be properly supported. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic exploded view of a television receiver apparatus according to Embodiment 1 of the present invention; 
         FIG. 2  is a plan view of a backlight; 
         FIG. 3  is a sectional view taken along the line in  FIG. 2 ; 
         FIG. 4  is a sectional view taken along the line IV-IV in  FIG. 2 ; 
         FIG. 5  is a sectional view taken along the line V-V in  FIG. 2 ; 
         FIG. 6  is a sectional view taken along the line VI-VI in  FIG. 2 ; 
         FIG. 7  is a graph showing a relationship between distances from an axis of symmetry L 1  and support heights of support portions arranged in a long side direction of an optical member; 
         FIG. 8  is a graph showing a relationship between distances from an axis of symmetry L 2  and support heights of support portions arranged in a short side direction of the optical member; 
         FIG. 9  is a sectional view taken along the line in  FIG. 2  of a diffuser plate being warped and deformed; 
         FIG. 10  is a sectional view taken along the line IV-IV in  FIG. 2  of the diffuser plate being warped and deformed; 
         FIG. 11  is a sectional view taken along the line V-V in  FIG. 2  of the diffuser plate being warped and deformed; 
         FIG. 12  is a sectional view taken along the line VI-VI in  FIG. 2  of the diffuser plate being warped and deformed; 
         FIG. 13  is a sectional view of a liquid crystal display device according to Embodiment 2 of the present invention; 
         FIG. 14  is a sectional view of a diffuser plate being warped and deformed; 
         FIG. 15  is a partial side view of a diffuser plate according to another embodiment (15); and 
         FIG. 16  is a partial side view of a diffuser plate according to a further embodiment (16). 
     
    
    
     DESCRIPTION OF SYMBOLS 
       10  . . . backlight (lighting device for a display device),  11  . . . liquid crystal panel (display panel),  13  . . . chassis,  15  . . . cold cathode tube (light source),  16  . . . optical member,  16 A . . . diffuser plate,  20  . . . support component,  24  . . . mounting plate,  26  . . . light source gripping portion,  27  . . . support portion,  27 H . . . higher support portion,  27 L . . . lower support portion, D . . . liquid crystal display device (display device), TV . . . television receiver apparatus 
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Embodiment 1 
     Embodiment 1 of the present invention will be described with reference to  FIGS. 1 to 12 . In Embodiment 1, a liquid crystal display device D is exemplified as a display device. 
     The liquid crystal display device D has a generally horizontally oriented rectangular shape, and includes, as shown in  FIG. 3 , a liquid crystal panel  11  as a display panel and a backlight  10  as an external light source (illumination device) of the liquid crystal panel  11  assembled to each other and held by a bezel  12  placed on a front side. The liquid crystal panel  11  is placed on a front surface side of the backlight  10 , and the backlight  10  illuminates the liquid crystal panel  11  from a back surface side. The liquid crystal display device D can be applied to a television receiver apparatus TV. The television receiver apparatus TV includes, as shown in  FIG. 1 , the liquid crystal display device D, front and back cabinets Ca and Cb that sandwich and house the liquid crystal display device D, a power supply P, a tuner T, and a stand S. 
     As shown in  FIG. 3 , the liquid crystal panel  11  has a known structure in which a liquid crystal that is a substance having varying optical properties with application of a voltage is sealed in a gap between a transparent TFT substrate and a transparent CF substrate. A TFT (Thin Film Transistor) as a switching element connected to source wiring and gate wiring perpendicular to each other is provided on the TFT substrate, and three color filters of red (R), green (G) and blue (B) are arranged in a matrix on the CF substrate. Also, a polarizing plate is attached to the side opposite to the liquid crystal of each substrate. 
     The backlight  10  is of a so-called direct type, and includes a chassis  13  having an opening surface on a front side (an upper side in  FIGS. 3 and 5 , a front surface side) that is a light emission side, a reflective sheet  14  laid in the chassis  13 , a plurality of cold cathode tubes  15  housed in the chassis  13 , an optical member  16  provided in an opening portion of the chassis  13 , that is, on the emission side of lights emitted from the cold cathode tubes  15 , positioning members (a lamp holder  17 , a holder  18 , and a frame  19  described later) that can position the optical member  16 , and a plurality of support components  20  (lamp clips) that can support the cold cathode tubes  15  and the optical member  16 . 
     The chassis  13  is made of metal, and formed into a rectangular on plan view and shallow substantially box shape having an opening surface on a front side as shown in  FIG. 2 . The reflective sheet  14  is made of synthetic resin, has a surface with white base color such as white with high reflectivity, and as shown in  FIG. 3 , is laid on an inner surface of the chassis  13  so as to substantially cover the entire inner surface. The reflective sheet  14  can guide the light emitted from each cold cathode tube  15  to the opening portion of the chassis  13 . 
     The cold cathode tube  15  is a kind of elongated linear light source extending in one direction along a bottom plate  13   a  of the chassis  13  or the plane direction of the optical member  16 , and is mounted in the chassis  13  with an axial direction thereof matching a long side direction of the chassis  13 . The plurality of cold cathode tubes  15  are arranged axially substantially in parallel with predetermined spaces therebetween. More specifically describing the space (pitch, distance) between adjacent cold cathode tubes  15 , as shown in  FIGS. 2 and 5 , a space between cold cathode tubes  15  placed in the middle in a short side direction of the chassis  13  or the optical member  16  is smallest, and the space progressively increases therefrom toward end sides. In other words, a density of arrangement of the cold cathode tubes  15  in the chassis  13  is higher on the middle side of a screen, and becomes progressively lower toward end sides of the screen. The cold cathode tubes  15  are arranged symmetrically with respect to an axis of symmetry L 1  in a middle position in the short side direction of the chassis  13 . 
     The cold cathode tube  15  is configured so that mercury or the like is sealed in an elongated glass tube having a circular section, an inner wall surface of the tube is coated with a fluorescent material, and electrodes are sealed in opposite end portions. A rubber holder  21  mounted to the chassis  13  is fitted to a non-light-emitting portion at each end of the cold cathode tube  15 . 
     The optical member  16  has a rectangular shape on plan view like the chassis  13  and the liquid crystal panel  11  as shown in  FIGS. 3 and 5 , is made of translucent synthetic resin, mounted to the opening portion of the chassis  13  and interposed between the group of cold cathode tubes  15  and the liquid crystal panel  11 . The optical member  16  includes a diffuser plate  16 A, a diffusion sheet  16 B, a lens sheet  16 C, and a luminance increasing sheet  16 D laminated in order from a back side (a lower side in  FIGS. 3 and 5 , a back surface side), and has a function of converting the light emitted from each cold cathode tube  15  as the linear light source into a uniform planar light or the like. The diffuser plate  16 A placed on the backmost side has a sufficiently larger thickness than other sheets  16 B to  16 D and has relatively high rigidity. The diffuser plate  16 A contains a plurality of diffusing particles dispersed in a transparent base material having a predetermined thickness, and is thus formed to be generally translucent. 
     The diffuser plate  16 A is sometimes warped and deformed by an influence of ambient temperature environment or the like. In this case, the sheets  16 B to  16 D are also deformed following the warped and deformed diffuser plate  16 A. If the optical member  16  is warped and deformed toward the liquid crystal panel  11  at this time, the optical member  16  presses the middle portion of the liquid crystal panel  11  to cause poor display. Thus, the diffuser plate  16 A is subjected to so-called previous warping so as to have a warping habit to be warped toward the cold cathode tube  15 . The previous warping is performed by heating only a surface on the front side (on the side opposite to the cold cathode tube  15 ) of the base material while the base material passes between upper and lower rollers in a process of producing the diffuser plate  16 A. Thus, the diffuser plate  16 A has a warping habit such that the heated-side surface is deformed to be recessed (the middle side is retracted from the outer peripheral end portion  16   b  toward the back side (toward the cold cathode tube  15 ). 
     The positioning member includes the lamp holder  17  and the holder  18  that constitute a frame-shaped catch member that receives the outer peripheral end portion  16   b  of the optical member  16  on the back side, and the frame  19  that constitutes a frame-shaped presser member that presses the outer peripheral end portion  16   b  of the optical member  16  from the front side. 
     The lamp holder  17  is made of synthetic resin having a surface with white base color such as white, and as shown in  FIGS. 2 and 3 , a pair of lamp holders  17  are mounted to opposite end positions in the long side direction of the chassis  13  and extend in the short side direction of the chassis  13 . The lamp holder  17  has a substantially box shape with an opening back surface side so as to collectively cover the rubber holders  21  mounted to the cold cathode tubes  15  from the front side. A catch  22  that can receive the optical member  16  is formed to be recessed with a step in an inner peripheral end portion on a front side surface of the lamp holder  17 . 
     The holder  18  is made of synthetic resin having a surface with white base color such as white, and as shown in  FIGS. 2 and 5 , a pair of holders  18  are mounted to opposite end positions in the short side direction of the chassis  13  and extend in the long side direction of the chassis  13 . Like the lamp holder  17 , a catch  23  for the optical member  16  is formed to be recessed with a step in an inner peripheral end portion on a front side surface of the holder  18 . 
     The frame  19  is made of metal and formed into a frame shape, and as shown in  FIGS. 3 and 5 , can press the outer peripheral end portion  16   b  of the optical member  16  substantially over the entire periphery from the front side. The frame  19  has, in the inner peripheral end portion, a presser surface facing a plate surface of the optical member  16 . The presser surface is placed with a slight clearance from a plate surface on the front side of the luminance increasing sheet  16 D on the frontmost side in the assembled state, and this allows thermal expansion or contraction of the optical member  16 . 
     A support component  20  is made of synthetic resin, and has an entire surface with white base color such as white with high light reflectivity. As shown in  FIGS. 2 and 5 , the support component  20  includes a mounting plate  24  along the bottom plate  13   a  of the chassis  13 , a locking portion  25  protruding from the mounting plate  24  toward a back side, a light source gripping portion  26  protruding from the mounting plate  24  toward a front side (toward the optical member  16 ), and a support portion  27  protruding from the mounting plate  24  toward the front side like the light source gripping portion  26 . 
     The mounting plate  24  has an elongated plate shape extending in the short side direction of the chassis  13 . On a back side surface of the mounting plate  24 , a pair of locking portions  25  are provided passing through mounting holes provided in the chassis  13  and lockable to hole edges on the back side. Thus, the support component  20  is held in a mounted state to the chassis  13 . In  FIGS. 3 ,  4 ,  9  and  10 , the locking portions  25  are not shown. 
     Meanwhile, on a front side surface of the mounting plate  24 , a pair of light source gripping portions  26  that can grip the cold cathode tubes  15  are provided. The light source gripping portions  26  are placed substantially in the same positions as the locking portions  25  in the plane direction of the bottom plate  13   a  of the chassis  13 . Each light source gripping portion  26  has a substantially C-shaped section with an opening portion on the front side, and the cold cathode tube  15  is mounted through the opening portion on the front side. The light source gripping portion  26  can be elastically deformed with attachment and detachment of the cold cathode tube  15 . Thus, each cold cathode tube  15  can be supported in a position at a predetermined height above the bottom plate  13   a  of the chassis  13 . The length of the mounting plate  24  and an installation position of the light source gripping portion  26  in each support component  20  correspond to the above described mounting position of the cold cathode tube  15  to the chassis  13 . 
     The support portion  27  is provided between the light source gripping portions  26  on the front side surface of the mounting plate  24 . An installation position of the support portion  27  is a central position of the mounting plate  24  and a middle position between the light source gripping portions  26 . A protrusion height of the support portion  27  is higher than that of the light source gripping portion  26 . The support portion  27  has a circular section cut in the plane direction of the diffuser plate  16 A, and is tapered to have a decreasing diameter from a base end toward a protruding end. Specifically, the support portion  27  has a generally conical pin shape. This can avoid the support portion  27  from blocking the light emitted from the cold cathode tube  15 . 
     The support portion  27  can support the diffuser plate  16 A in a predetermined height position by a tip portion thereof coming into contact with the diffuser plate  16 A. The support portion  27  has a substantially point shape with respect to the surface of the diffuser plate  16 A. The support portion  27  has a solid structure, and the entire support portion  27  is a secured part (substantially a rigid body) that cannot be elastically deformed. Thus, the diffuser plate  16 A is supported vertically (perpendicularly to the plane direction of the diffuser plate  16 A (optical member  16 ) by the support portion  27  in a fixed and unchanged position, that is, at a fixed and unchanged height. 
     The support components  20  having the above described configuration are arranged on the bottom plate  13   a  of the chassis  13  as described below. Specifically, as shown in  FIG. 2 , the support components  20  are arranged in a row linearly extending in the short side direction of the chassis  13 , and a plurality of the rows are arranged with predetermined spaces therebetween in the long side direction of the chassis  13 . For the rows of the support components  20 , three rows on the left and three rows on the right are arranged with respect to an axis of symmetry L 2  in the middle in the long side direction of the chassis  13  in  FIG. 2 , and these groups of rows are arranged symmetrically. In each of the left and right groups of rows of the support components  20 , the support components  20  in the middle row are arranged to be displaced in the short side direction of the chassis  13  from the support components  20  in the rows on the opposite sides thereof. Specifically, in each of the left and right groups of rows, the support components  20  are arranged in a zigzag (staggered) manner. Thus, the support portions  27  provided in the central positions of the support components  20  are also distributed in a zigzag manner in the surface of the diffuser plate  16 A, and arranged symmetrically with respect to the axis of symmetry L 2 . 
     With the support component  20  being mounted to the chassis  13 , the light source gripping portions  26  are placed in mounting positions of the cold cathode tubes  15 , and the support portion  27  is placed between adjacent cold cathode tubes  15 . At this time, the support portion  27  is placed in a middle position between the adjacent cold cathode tubes  15 . 
     As shown in  FIGS. 3 to 6 , the support portions  27  on the support components  20  support the diffuser plate  16 A at different heights according to mounting positions to the chassis  13 . Specifically, the support portions  27  placed on the middle side of the bottom plate  13   a  of the chassis  13 , that is, the diffuser plate  16 A have lower protrusion heights, and the support portions  27  placed on the end side have higher protrusion heights. 
     Specifically, among the support portions  27 , four support portions  27  placed closest to the ends in the long side direction and the short side direction of the diffuser plate  16 A, that is, closest to four corners of the rectangular diffuser plate  16 A have the highest height as shown in  FIGS. 4 and 6 . These support portions  27  are higher support portions  27 H that support the diffuser plate  16 A at the highest level of all the support portions. Meanwhile, among the support portions  27 , four support portions  27  placed closest to the middle side in the long side direction and the short side direction of the diffuser plate  16 A, that is, closest to the central position of the diffuser plate  16 A have the lowest height as shown in  FIGS. 3 and 5 . These support portions  27  are lower support portions  27 L that support the diffuser plate  16 A at the lowest level of all the support portions. 
     The heights of the support portions  27  other than the higher support portions  27 H and the lower support portions  27 L gradually decrease from the end side toward the middle side in the long side direction and the short side direction of the diffuser plate  16 A. In other words, the heights of the support portions  27  decreases with increasing distance from the higher support portions  27 H closest to the end, and increases with increasing distance from the lower support portions  27 L closest to the middle. Thus, the support portions  27  other than the higher support portions  27 H at the highest level and the lower support portions  27 L at the lowest level may be lower support portions or higher support portions described in Claims according to which support portion  27  is a comparison target of the support height. 
     Tip portions of the support portions  27  are connected to form a curve of a gentle arc shape viewed from a lateral side, and the shape of the curve matches the warped shape of the diffuser plate  16 A. Specifically, the height positions of the tip portions of the support portions  27  are set in positions matching a supposed warped shape of the diffuser plate  16 A. 
     Specifically, for curves obtained by connecting the tip portions of the support portions  27  arranged in the long side direction of the diffuser plate  16 A, as shown in  FIG. 7 , a curve of a row on the middle side in the long side direction (a lower curve in  FIG. 7 ) is generally lower than a curve of a row on the end side (an upper curve in  FIG. 7 ). Similarly, for curves obtained by connecting the tip portions of the support portions  27  arranged in the short side direction of the diffuser plate  16 A, as shown in  FIG. 8 , a curve of a row on the middle side in the long side direction (a lower curve in  FIG. 8 ) is generally lower than a curve of a row on the end side (an upper curve in  FIG. 8 ). The same applies to curves obtained by connecting tip portions of the support portions  27  arranged diagonally with respect to the long side direction and the short side direction of the diffuser plate  16 A. 
     Among the support portions  27 , the higher support portions  27 H at the highest level are placed at a lower level than the catches  22  and  23  as shown in  FIGS. 4 and 6 , and the support portions  27  are placed in a position at a predetermined gap from the back side surface of the diffuser plate  16 A in no contact therewith when the diffuser plate  16 A is straight and substantially parallel to the bottom plate  13   a  of the chassis  13 , that is, the diffuser plate  16 A is not warped. In this state, a gap between the tip portion of the support portion  27  and the back side surface of the diffuser plate  16 A is largest in the lower support portion  27 L at the lowest level and smallest in the higher support portion  27 H. Thus, the optical member  16  can be warped and deformed by the gap ensured between the optical member  16  and the support portion  27 . Specifically, the support portion  27  does not support the diffuser plate  16 A when the diffuser plate  16 A is not warped, and supports the diffuser plate  16 A after the diffuser plate  16 A is warped. 
     Meanwhile, the lower support portions  27 L at the lowest level among the support portions  27  are placed at a higher level than the cold cathode tube  15  as shown in  FIGS. 3 and 5 . Thus, even when the diffuser plate  16 A is warped and deformed to the maximum, the diffuser plate  16 A is supported by the support portion  27  and thus held in a position at a predetermined gap from the cold cathode tube  15  in no contact therewith. Thus, a lamp image of the cold cathode tube  15  is hard to be visually identified by a user. 
     The liquid crystal display device D having the above described configuration is produced as described below. The liquid crystal panel  11  and the backlight  10  are individually produced and assembled using the bezel  12  or the like to produce the liquid crystal display device D. In the backlight  10 , the reflective sheet  14  is laid in the chassis  13 , then each support component  20  is mounted to a predetermined position, and each cold cathode tube  15  having the rubber holders  21  fitted to the opposite ends is mounted, and thus the light source gripping portion  26  of the support component  20  elastically grips the cold cathode tube  15  in a predetermined height position. 
     Then, when the lamp holder  17  and the holder  18  are mounted in the chassis  13 , the optical member  16  is placed on the catches  22  and  23  of the lamp holder  17  and the holder  18  in order of the diffuser plate  16 A, the diffusion sheet  16 B, the lens sheet  16 C, and the luminance increasing sheet  16 D. Then, the frame  19  is mounted to position the optical member  16 . 
     In the liquid crystal display device D produced as described above, when each cold cathode tube  15  is lit in use, heat generated from the cold cathode tube  15  increases temperature in the chassis  13 . Then, the diffuser plate  16 A may be warped depending on the temperature environment. In this case, since the support portions  27  are provided with a predetermined gap therebetween on the back side of the diffuser plate  16 A to be ready to receive the diffuser plate  16 A, the diffuser plate  16 A can be warped and deformed in both the long side direction and the short side direction. Thus, as compared with a device in which a diffuser plate  16 A cannot be warped and deformed, a groan is hard to be caused. 
     The diffuser plate  16 A is subjected to previous warping as described above, and thus deformed so that the middle portion thereof is warped and deformed so as to be recessed toward the cold cathode tube  15 . At this time, in the diffuser plate  16 A, the middle side portion  16   a  is warped and deformed into an arc shape with the outer peripheral end portions  16   b  supported by the catches  22  and  23  of the lamp holder  17  and the holder  18  as fulcrums. When the diffuser plate  16 A is warped, the sheets  16 B to  16 D laminated on the front side are warped and deformed following the diffuser plate  16 A. At this time, the diffuser plate  16 A is warped and deformed only in the long side direction or the short side direction in some cases, and warped and deformed in both the long side direction and the short side direction in other cases. 
     When the diffuser plate  16 A is warped and deformed to some degree, the tip portion of each support portion  27  abuts against the back side surface of the diffuser plate  16 A. For the support portions  27  arranged in a distributed manner on the surface of the diffuser plate  16 A, the height positions of the tip portions gradually decrease from the end side toward the middle side of the diffuser plate  16 A, and thus the diffuser plate  16 A can be supported in a height position matching the warped shape in the long side direction. 
     Specifically, when the diffuser plate  16 A is warped in the long side direction, as shown in  FIGS. 9 and 10 , the support heights of the support portions  27  arranged in the long side direction gradually decrease from the end side toward the middle side, thereby allowing the warped and deformed diffuser plate  16 A to be properly supported. Meanwhile, when the diffuser plate  16 A is warped in the short side direction, as shown in  FIGS. 11 and 12 , the support heights of the support portions  27  arranged in the short side direction gradually decrease from the end side toward the middle side, thereby allowing the warped and deformed diffuser plate  16 A to be properly supported. This can control excessive warping deformation of the diffuser plate  16 A. 
     The lower support portion  27 L at the lowest level of the support portion  27  is set at a higher level than the cold cathode tube  15 , and the diffuser plate  16 A is reliably prevented from coming into contact with the cold cathode tube  15 . Even when the diffuser plate  16 A is warped and deformed to the maximum, a sufficient distance is ensured from the cold cathode tube  15 , thereby preventing a so-called lamp image from being visually identified. This can maintain high display quality of the liquid crystal display device D. 
       FIGS. 9 to 12  show the case where the diffuser plate  16 A is warped to the maximum and abuts against all the support portions  27 , but there is a case where some support portions  27  abut against the diffuser plate  16 A but the other support portions  27  do not abut against the diffuser plate  16 A depending on the warped state of the diffuser plate  16 A, and all the support portions  27  do not always abut against the diffuser plate  16 A as shown. 
     As described above, according to this embodiment, the plurality of support portions  27  have the point shapes with respect to the surface of the diffuser plate  16 A (optical member  16 ), are arranged in the surface in the distributed manner, and include the lower support portion  27 L and the higher support portion  27 H that support the diffuser plate  16 A at different heights, and the lower support portion  27 L is placed on the middle side of the diffuser plate  16 A and the higher support portion  27 H is placed on the end side of the diffuser plate  16 A, thereby allowing the diffuser plate  16 A to be supported in the position matching the warped shape. Thus, the diffuser plate  16 A can be supported in a state where the diffuser plate  16 A can be warped and deformed and the diffuser plate  16 A is hard to be bent, thereby allowing the diffuser plate  16 A to be properly supported. 
     The support portions  27  support the diffuser plate  16 A at gradually increasing heights from the middle side toward the end side of the diffuser plate  16 A, thereby allowing the warped and deformed diffuser plate  16 A to be supported at a more proper support height. 
     The support portions  27  are arranged in a zigzag manner. Thus, the support portions  27  can be efficiently distributed in the surface of the diffuser plate  16 A, thereby allowing the diffuser plate  16 A to be more properly supported. 
     The support portions  27  are linearly arranged in the short side direction of the rectangular diffuser plate  16 A, thereby allowing the diffuser plate  16 A to be satisfactorily supported. 
     The support portions  27  are linearly arranged in the long side direction of the rectangular diffuser plate  16 A, thereby allowing the diffuser plate  16 A to be satisfactorily supported. 
     The support portions  27  are tapered. This can avoid the support portions  27  from blocking the light emitted from the cold cathode tube  15 . 
     The support portions  27  have surfaces with white base color. Thus, the light emitted from the cold cathode tube  15  can be reflected by the surfaces of the support portions  27  and guided toward the diffuser plate  16 A, thereby increasing use efficiency of the light. 
     The support portion  27  includes the mounting plate  24  mounted to the chassis  13 , and the light source gripping portion  26  that can grip the cold cathode tube  15  is provided on the mounting plate  24  in the lateral position of the support portion  27 . This allows the support portion  27  to also have a function of gripping the cold cathode tube  15 . 
     The diffuser plate  16 A is subjected to previous warping so as to be warped and deformed toward the cold cathode tube  15  as the cold cathode tube  15  is lit. This prevents the diffuser plate  16 A from being warped and deformed in a reverse direction, thereby allowing the support portion  27  to reliably support the diffuser plate  16 A. 
     Further, the previous warping includes heating treatment of the surface on the side opposite to the cold cathode tube  15  of the base material of the diffuser plate  16 A. This allows previous warping without adding another member to the diffuser plate  16 A, and can reduce production costs of the diffuser plate  16 A. 
     Embodiment 2 
     Embodiment 2 of the present invention will be described with reference to  FIGS. 13 and 14 . In Embodiment 2, the support height of the support portion is changed. In Embodiment 2, overlapping descriptions will be omitted on the same structure, operation and advantage as those in Embodiment 1. 
     In a backlight  10 ′, all spaces between cold cathode tubes  15 ′ housed in a chassis  13 ′ are the same though not shown. Thus, a length of a mounting plate  24 ′ of a support component  20 ′ and forming positions of a light source gripping portion  26 ′ and a locking portion on the mounting plate  24 ′ are all the same irrespective of a mounting position of the support component  20 ′ to the chassis  13 ′. In Embodiment 2, a screen size of a liquid crystal panel  11 ′ is larger than that in Embodiment 1, and thus the number of support components  20 ′ installed is also larger than that in Embodiment 1. 
     As shown in  FIG. 13 , among support components  20 ′, a support component  20 ′ placed closest to an end of the diffuser plate  16 A′ and a support component  20 ′ adjacent thereto include support portions  27 ′ of the same height, and have the same shape. Specifically, support portions  27 ′ of support components  20 ′ adjacent to four support components  20 ′ closest to four corners of the diffuser plate  16 A′ in a long side direction and a short side direction among the support components  20 ′ are higher support portions  27 H′ at the highest level like the four support components  20 ′ closest to the corners. 
     When the diffuser plate  16 A′ is warped as each cold cathode tube  15 ′ is lit, as shown in  FIG. 14 , each support portion  27 ′ abuts against a back surface of the diffuser plate  16 A′ to support the diffuser plate  16 A′ at a height matching the warped shape. At this time, the diffuser plate  16 A′ tends to be less warped on an end side than on a middle side. Thus, the diffuser plate  16 A′can be satisfactorily supported even if the higher support portion  27 H′ having the same support height are provided adjacent to each other on the end side of the diffuser plate  16 A′ as in this embodiment. 
     As described above, according to this embodiment, among the support portions  27 ′, the support portion  27 ′ closest to the end of the diffuser plate  16 A′ and the support portion  27 ′ adjacent thereto support the diffuser plate  16 A′ at the same height, and the support components  20 ′ including these support portions  27 ′ have the same shape, thereby reducing the number of types of the support components  20 ′ and thus reducing production costs. 
     Other Embodiments 
     The present invention is not limited to the embodiments described above with reference to the drawings, but the technical scope of the present invention also covers, for example, the following embodiments. 
     (1) The shape of the support portion may be changed. For example, the support portion may be formed into a pyramidal shape or have a rounded tip portion. Also, the support portion may have a fixed diameter (thickness) over the entire length, and may be formed into a cylindrical or prismatic shape. 
     (2) The present invention also covers a case where one support component includes a plurality of support portions. In this case, heights of the support portions may be different or the same. 
     (3) When all the support portions have the different heights as in Embodiment 1, constant pitch arrangement in which all the spaces between the cold cathode tubes are the same may be chosen. Similarly, when some support portions have the same heights as in Embodiment 2, variable pitch arrangement in which the spaces between the cold cathode tubes are variable may be chosen. 
     (4) The present invention also covers a combination of constant pitch arrangement and variable pitch arrangement for arrangement of the cold cathode tubes, for example, with the constant pitch arrangement on the middle side of the optical member and the variable pitch arrangement on the end side of the optical member. 
     (5) In the above described embodiments, the cold cathode tubes are arranged symmetrically, but the present invention also covers a case where the cold cathode tubes are arranged asymmetrically. 
     (6) In the above described embodiments, the tip portion of the higher support portion closest to the end of the diffuser plate is placed at the height in no contact with the diffuser plate that is not warped, but the present invention also covers a case where the tip portion of the higher support portion is located at substantially the same height as the catch of the lamp holder or the holder, and comes into contact with the diffuser plate that is not warped. 
     (7) In the above described embodiments, the support portion is interposed between the cold cathode tubes, but the support portions do not always need to be provided between all the cold cathode tubes, and the present invention also covers a case with the support portions partially omitted. 
     (8) In the above described embodiments, the support components and the support portions are arranged in the zigzag manner on the bottom plate of the chassis, but the present invention also covers a case, for example, where the support components and the support portions are arranged in a lattice manner. 
     (9) In the above described embodiments, the support portions are arranged symmetrically on the bottom plate of the chassis, but the present invention also covers a case where the support portions are arranged asymmetrically. 
     (10) In the above described embodiments, the support component including the support portions has the white surface, but not limited to white, and for example, other white base colors such as semi-opaque may be chosen. Colors other than the white base color may be chosen. 
     (11) In the above described embodiments, the light source gripping portion that grips the cold cathode tube is provided in the support component, but the light source gripping portion may be omitted. 
     (12) In the above described embodiments, the mounting plate is provided on the support component, but the mounting plate may be omitted and a locking portion may be provided on the back surface of the support portion for mounting to the chassis. 
     (13) In the above described embodiments, the support portion is integrally formed with the support component, but the support portion may be produced separately from a body of the support component and integrated by assembly. Specifically, the body of the support component is formed to have a common structure, and multiple types of support portions are separately formed to have different heights, thereby reducing production costs. The support portion may be integrated with the body of the support component by mechanical joining means such as fitting or chemical joining means such as an adhesive. 
     (14) In the above described embodiments, as the previous warping of the diffuser plate, heat treatment of one side of the base material is performed in a production process of the diffuser plate, but other methods may be used. Specifically, methods in the following (15) and (16) may be used. 
     (15) As a specific example of the previous warping, as shown in  FIG. 15 , a previous warping layer  31  constituted by beads  30  is formed on a surface on the side of the liquid crystal panel (the side opposite to the cold cathode tube) of a base material  29  of a diffuser plate  28 , and the previous warping layer  31  has a linear expansion coefficient lower than that of the base material  29  placed on the side of the cold cathode tube. Thus, this provides a warping habit to the diffuser plate  28  so as to be reliably warped toward the cold cathode tube when the cold cathode tube is lit and the temperature in the backlight is increased. The previous warping layer  31  is formed by applying or dropping a predetermined solvent mixed with a plurality of beads  30  on a surface of the base material  29 , and then volatilizing or draining the solvent. Other than the above, the previous warping layer  31  may be formed on the side of the cold cathode tube of the base material  29 , and the previous warping layer  31  placed on the side of the cold cathode tube may have a linear expansion coefficient higher than that of the base material  29 . 
     (16) As a specific example of the previous warping, as shown in  FIG. 16 , a previous warping layer  35  formed of a sheet material  34  is formed on the side of the liquid crystal panel of a base material  33  of a diffuser plate  32 , and the previous warping layer  35  has a linear expansion coefficient lower than that of the base material  33 . Thus, the same advantage of previous warping as in (15) can be obtained. The previous warping layer  35  is formed by attaching a synthetic resin sheet material  34  to a surface of the base material  33 , and an adhesive layer (not shown) of an acrylic UV curing adhesive, an acrylic pressure sensitive adhesive, or the like may be formed between the sheet material  34  and the base material  33  in attachment. Other than the above, the previous warping layer  35  may be formed on the side of the cold cathode tube of the base material  33 , and the previous warping layer  35  placed on the side of the cold cathode tube may have a linear expansion coefficient higher than that of the base material  33 . 
     (17) In the above described embodiments, the previous warping of the diffuser plate is performed, but the diffuser plate can be predicted to be warped toward the cold cathode tube without previous warping in some cases according to design of a backlight. In such a case, a diffuser plate that is not subjected to previous warping can be used. Other than the above, for example, when the optical member is partially pressed from the side of the liquid crystal panel to forcedly warp and deform the diffuser plate toward the cold cathode tube, a diffuser plate that is not subjected to previous warping can be used. 
     (18) In the above described embodiments, the cold cathode tube is exemplified as the light source, but the present invention may be applied to a case including a different type of linear light source such as a hot cathode tube or a fluorescent tube or a point light source such as an LED as a light source. 
     (19) In the above described embodiments, the liquid crystal display device using the liquid crystal panel as a display panel is exemplified, but the present invention can be applied to a display device using a different type of display panel. 
     (20) In the above described embodiments, the television receiver apparatus including the tuner is exemplified, but the present invention can be applied to a display device that does not include a tuner.