Abstract:
A display apparatus, comprising: a light source emitting light; a display panel displaying an image on a front face of the display panel, and facing the light source; and a diffusion section arranged between the light source and the display panel, wherein the diffusion section includes a diffusion sheet-fixed to a circumferential portion of the display panel via a frame body, and facing the display panel with a distance between the diffusion sheet and the display panel, and an optical sheet arranged in a gap between the display panel and the diffusion sheet.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the national phase under 35 U.S.C. §371 of PCT International Application No. PCT/JP2014/058755 which has an International filing date of Mar. 27, 2014 and designated the United States of America. 
     
    
     FIELD 
       [0002]    The present invention relates to a display apparatus which displays an image on a display panel such as a liquid crystal panel, for example. 
       BACKGROUND 
       [0003]    In recent years, a display apparatus comprising a liquid crystal panel as an image display section has been used widely. Such a display apparatus comprises a backlight arranged on a back face side of the liquid crystal panel. 
         [0004]    The backlights of various types are employed. As a backlight of one type, a direct-type backlight is employed where light sources are arranged at positions facing the whole back face of the liquid crystal panel. 
         [0005]    The display apparatus comprising the direct-type backlight further comprises: light sources aligned on a bottom face of a backlight chassis having a shallow-box shape; a liquid crystal panel covering an opening portion of the back light chassis; and a diffusion section arranged between the light source and the liquid crystal panel. 
         [0006]    The diffusion section is provided with a diffusion plate supported by the back light chassis and with an optical sheet supported by the diffusion plate and arranged between the liquid crystal panel and the diffusion plate (for example, Japanese Patent Application Laid-Open No. 2009-122160). 
         [0007]    This type of display apparatus diffuses light emitted from the light source by the diffusion plate and the optical sheet, modulates the diffused light by the liquid crystal panel, and transmits the light to display an image on a front face of the liquid crystal panel. 
         [0008]    By the way, the diffusion plate is required for the conventional display apparatus. 
         [0009]    The diffusion plate functions as a supporting member for the optical sheet constituting a part of the diffusion section, and has a certain amount of thickness so that the optical sheet is not slack. 
         [0010]    For this reason, in a case where the display apparatus has a screen size of 60 inches, the diffusion plate has a weight of 2 to 3 kg. 
         [0011]    Also, in a case where the display apparatus has a screen size of 80 inches, the diffusion plate has a weight over 5 kg. 
         [0012]    Accordingly, the weight of the diffusion plate contributes to the inhibition of the reduction in weight of the large-sized display apparatus. 
       SUMMARY 
       [0013]    According to an aspect of the embodiment, an apparatus comprising: a light source emitting light; a display panel displaying an image on a front face of the display panel, and facing the light source; and a diffusion section arranged between the light source and the display panel, wherein the diffusion section includes a diffusion sheet fixed to a circumferential portion of the display panel via a frame body, and facing the display panel with a distance between the diffusion sheet and the display panel, and an optical sheet arranged in a gap between the display panel and the diffusion sheet. 
         [0014]    Additional objects and advantages of the embodiment will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
         [0015]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0016]      FIG. 1  is a perspective view schematically showing an external appearance of a display apparatus according to Embodiment 1. 
           [0017]      FIG. 2  is a transverse sectional view by a line II-II of  FIG. 1 . 
           [0018]      FIG. 3  is an explanatory view showing a mounting procedure of a diffusion sheet and an optical sheet. 
           [0019]      FIG. 4  is an explanatory view showing the mounting procedure of the diffusion sheet and the optical sheet. 
           [0020]      FIGS. 5A, 5B and 5C  are enlarged sectional views showing examples of other shapes of positioning structures. 
           [0021]      FIG. 6  is a transverse sectional view by a line II-II of  FIG. 1 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
       [0022]    Hereinafter, the present invention will be described in detail with reference to the drawings showing Embodiments thereof. FIG. is a perspective view schematically showing an external appearance of a display apparatus according to Embodiment 1. The illustrated display apparatus comprises a liquid crystal panel  1  for image display (display panel) of a rectangular plate shape, and a backlight  2  which irradiates the liquid crystal panel  1  with light. 
         [0023]    To the liquid crystal panel  1 , a front cabinet  10  of a rectangular frame shape is mounted so as to border a circumferential portion of a front face (image display surface) of the liquid crystal panel  1  over a suitable width.  FIG. 1  shows the image display surface of the liquid crystal panel  1  which is exposed within a frame of the front cabinet  10 . The backlight  2  is mounted on a back face side of the liquid crystal panel  1 . The display apparatus further comprises a stand  13 , is supported on a suitable placement plane via the stand  13 , and is used with the image display surface of the liquid crystal panel  1  being maintained in a vertical posture, as shown in  FIG. 1 . 
         [0024]      FIG. 2  is a transverse sectional view by a line II-II of  FIG. 1 . As shown in  FIG. 2 , the backlight  2  is provided with a backlight chassis  20  of an outer case of a shallow-box shape and with a plurality of LEDs (Light Emitting Diodes)  23  arranged on a bottom plate of the backlight chassis  20 . The LEDs  23  are aligned and mounted in vertical and lateral directions of one face of an LED substrate  22 . The LEDs  23  are mounted to an inner face of the bottom plate of the backlight chassis  20  with a mounting face of the LED substrate  22  being directed to an opening side. 
         [0025]    The inner face of the backlight chassis  20  is covered over the whole face including the bottom plate and side plates with a reflective sheet  21  made of resin having an excellent light reflectivity. The backlight chassis  20  is provided with a flange portion  20   a  arranged around the backlight chassis  20  so that the flange portion  20   a  projects from an opening portion thereof outward. A circumferential portion of the reflective sheet  21  is superposed on the flange portion  20   a , and is held and mounted between the flange portion  20   a  and a holding frame  27  fitted onto an outside of the flange portion  20   a . The reflective sheet  21  also covers the LEDs  23  arranged on the bottom plate of the backlight chassis  20 . A plurality of the LED substrates  22  where the LEDs  23  are mounted are exposed on a surface side of the reflective sheet  21  through through-holes formed in their corresponding positions. That is, the plurality of LED substrates  22  are exposed to an opening side of the backlight chassis  20 . 
         [0026]    The liquid crystal panel  1  is mounted so that the front cabinet  10  bordering a circumferential portion of the front face side thereof is fitted onto the outside of the holding frame  27 , and a circumferential portion of the back face thereof is in contact with the holding frame  27 , and the liquid crystal panel  1  is held between the holding frame  27  and the front cabinet  10 . The display apparatus comprises a diffusion section between the back face of the liquid crystal panel  1  mounted in this manner and the LEDs (light sources)  23  aligned on a bottom face of the backlight chassis  20 . 
         [0027]    The diffusion section is provided with one diffusion sheet  24  and two optical sheets  25 . The diffusion sheet  24  is a sheet in which a resin fiber, such as PET (polyethylene terephthalate) or PC (polycarbonate), is intertwined in the form of a felt, equally diffuses incident light entering from one face therein, and emits it from the other face. The optical sheet  25  is a sheet made of a resin material, such as PET or PC, and has an optical action, such as a prism action or a lens action. 
         [0028]    The diffusion sheet  24  is mounted to the back face of the liquid crystal panel  1  via a later-described frame body  26 , and is supported so as to face the back face with a distance corresponding to a thickness of the frame body  26  therebetween. Two optical sheets  25  are supported so as to be superposed on the diffusion sheet  24  inside the frame body  26 , and are arranged in a gap between the diffusion sheet  24  and the back face of the liquid crystal panel  1 . 
         [0029]    In the display apparatus configured as described above, light emitted from the LED  23  reaches the diffusion section directly or by reflecting on the reflective sheet  21 , is diffuses by the diffusion sheet  24 , and is condensed by the optical sheet  25 , so that the back face of the liquid crystal panel  1  is irradiated with light. The liquid crystal panel  1  modulates irradiation light and causes it to transmit so as to display an image on the front face thereof. 
         [0030]      FIG. 3  is an explanatory diagram showing the mounting procedure of the diffusion sheet  24  and the optical sheet  25 . The diffusion sheet  24  has a rectangular shape. A vertical and lateral dimensions of the diffusion sheet  24  are smaller than a vertical and lateral dimensions of the liquid crystal panel  1  so that the liquid crystal panel  1  covers the diffusion sheet  24 . The frame body  26  is a rectangular frame which has an opening in a central part thereof. A vertical and lateral dimensions of the frame body  26  are substantially the same as those of the diffusion sheet  24  so that the frame body  26  is arranged along a circumferential portion of the diffusion sheet  24 . The frame body  26  is fixed to the circumferential portion of the diffusion sheet  24  by an adhesion layer. The optical sheet  25  has a rectangular shape. A vertical and lateral dimensions of the optical sheet  25  are slightly smaller than those of the opening of the frame body  26  so that the frame body  26  covers a circumferential portion of the optical sheet  25 . The optical sheet  25  is fitted into the frame body  26  from a front face thereof and thereby is arranged on a front face of the diffusion sheet  24 . The diffusion sheet  24  is fixed to the back face of the liquid crystal panel  1  throughout the circumferential portion via the frame body  26  by an adhesion layer. 
         [0031]    Moreover, the display apparatus is configured so that the liquid crystal panel  1  is placed on the holding frame  27 , the front cabinet  10  is fitted onto the outside of the holding frame  27 , and the liquid crystal panel  1  is held between the holding frame  27  and the front cabinet  10  to cover the opening portion of the backlight chassis  20 . 
         [0032]    The diffusion sheet  24  is fixed to the back face of the liquid crystal panel  1  throughout the circumferential portion via the frame body  26 . Thereby, the diffusion sheet  24  is suspended by the liquid crystal panel  1  of a supporting member with a distance between the diffusion sheet  24  and the back face of the liquid crystal panel  1 . The diffusion sheet  24  suspended in this manner is a thin sheet, but it can function as a supporting member of the optical sheet  25 . The display apparatus is arranged between the LED  23  functioning as the light source and the liquid crystal panel  1 , and the diffusion section which diffuses light emitted from the LED  23  to irradiate the liquid crystal panel  1  with the light can be provided with three sheets of the diffusion sheet  24  and the optical sheets  25  and  25 . This eliminates the need for a thick diffusion plate in the display apparatus. For this reason, the display apparatus can support the diffusion sheet  24  with the liquid crystal panel  1 , thereby the weight of the display apparatus can be reduced without the diffusion plate. 
         [0033]    It should be noted that the frame body  26  is fixed to the diffusion sheet  24  and the liquid crystal panel  1  with a double-sided tape, an adhesive, etc. in this Embodiment, but it may also be fixed to the diffusion sheet  24  and the liquid crystal panel  1  by welding. 
       Embodiment 2 
       [0034]      FIG. 4  is an explanatory view showing the mounting procedure of the diffusion sheet  24  and the optical sheet  25 . Hereinafter, configurations and functions other than configurations and actions described especially are the same as those in Embodiment 1 and are thus not described for the sake of simplicity. The display apparatus has a positioning structure  28  which positions the optical sheet  25  and the frame body  26 . The optical sheet  25  is provided with positioning protrusions (protrusions or fitting protrusions)  251  protruding from the circumferential portion thereof outward on both long sides of the optical sheet  25 , respectively. Two discontinuous parts  261  where a part of a circumferential direction of the frame body  26  is discontinuous (or absent) are provided in the frame body  26 . The discontinuous parts  261  are arranged in positions corresponding to the positioning protrusions  251 . 
         [0035]    The positioning protrusion  251  is engaged with the discontinuous part  261 , thereby positioning the optical sheet  25  in a plane direction. This allows an operator to mount the optical sheet  25  to the frame body  26  easily. 
         [0036]    The positioning structure  28  is not limited to the above-described shape.  FIGS. 5A, 5B and 5C  are enlarged sectional views showing examples of other shapes of the positioning structures  28 . As shown in  FIG. 5A , the positioning protrusion  251  is provided with an insertion hole  252  which penetrates the optical sheet  25  in a thickness direction of the optical sheet  25 . The frame body  26  is provided with a thin-walled part  262  which is thinner than other portions, and with a protrusion  263  which vertically protrudes with respect to a face of the optical sheet  25 . A position of the protrusion  263  is matched with that of the insertion hole  252 . 
         [0037]    The protrusion  263  is inserted into the insertion hole  252 , thereby positioning the optical sheet  25  in the plane direction. This allows an operator to mount the optical sheet  25  to the frame body  26  more easily. 
         [0038]    As shown in  FIG. 5B , the positioning protrusion  251  is provided with a locking part  255  which protrudes in a direction orthogonal to a protruding direction of the positioning protrusion  251 . The positioning protrusion  251  is fitted into the discontinuous part  261  from a front face, and the optical sheet  25  can thereby be locked to the frame body  26 . 
         [0039]    The locking part  255  is locked to the discontinuous part  261 , thereby the optical sheet  25  can be correctly positioned with respect to the frame body  26 . 
         [0040]    As shown in  FIG. 5C , the frame body  26  is provided with a fitting recess  264  in an inner circumferential surface thereof. A position of the fitting recess  264  is matched with that of the positioning protrusion  251 . 
         [0041]    The positioning protrusion  251  is fitted into the fitting recess  264 , thereby the optical sheet  25  can be positioned with respect to the frame body  26 . 
         [0042]    The display apparatus comprises no hole in the frame body  26 . it is difficult for dust to enter between the optical sheet  25  and the diffusion sheet  24 . This can prevent the shadow by the dust from being displayed on the front face of the liquid crystal panel  1 . 
       Embodiment 3 
       [0043]      FIG. 6  is a transverse sectional view by a line II-II of  FIG. 1  and shows a left side of an upper face of the display apparatus. Hereinafter, configurations and actions other than configurations and actions described especially are the same as those in Embodiment 2 and their descriptions are thus not described for the sake of simplicity. Sizes of optical sheets  253  and  254  are substantially the same as that of the diffusion sheet  24 . The optical sheet  253  is fixed to the liquid crystal panel  1  via a frame body  265 . The optical sheet  254  is fixed to the optical sheet  253  via a frame body  266 . The diffusion sheet  24  is fixed to a circumferential portion of the optical sheet  254  via a frame body  267 . The liquid crystal panel  1 , the frame bodies  265 ,  266 ,  267 , the optical sheets  253 ,  254 , and the diffusion sheet  24  can be fixed with a double-sided tape, an adhesive, etc. 
         [0044]    Since the size of the optical sheet  25  is substantially the same as that of the diffusion sheet  24 , the display apparatus emits light diffused near the circumferential portion of the optical sheet  25  to the circumferential portion of the liquid crystal panel  1 , so as to display an image on the circumferential portion of the liquid crystal panel  1 . This can narrow a width of a vertical direction or a lateral direction of the front cabinet  10  in the display apparatus. 
         [0045]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiment(s) of the present invention(s) has(have) been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.