Patent Publication Number: US-2006018106-A1

Title: Frame assembly and electronic device

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to a frame assembly for use as an outer casing or housing of various electronic devices, and an electronic unit having an electronic device such as a flat display panel, e.g., a liquid-crystal display panel, mounted in a frame assembly.  
      Flat display panels such as liquid-crystal display panels and plasma display panels have frame components attached thereto and are mounted in frame assemblies.  
      Japanese Patent Laid-open No. 2004-69822 discloses a frame structure including holders mounted on and gripping left and right skirts of a rear frame of a flat display panel and holders mounted on and gripping left and right ends of a front transparent panel of the flat display panel.  
      Japanese Patent Laid-open No. 2004-61922 discloses a housing mounted on a rear side of a flat display panel and speaker storage regions on left and right ends of a front glass plate of the flat display panel.  
      There is a demand for a flat display panel structure having a flat display panel with upper, lower, left, and right sides surrounded by a frame for improved mechanical strength and appearance.  
      A frame assembly for use in such a flat display panel structure may include a frame having upper, lower, left, and right frame members formed integrally together. If the upper, lower, left, and right frame members are integrally molded, then the frame can easily be manufactured.  
      According to another demand for better appearance, the above frame is made of metal such as aluminum, and even if the flat display panel has a large screen size, the upper, lower, left, and right frame members of the frame are constructed as side plates that are thin in vertical and horizontal directions and that have a certain width along the depth, i.e., in a direction perpendicular to the screen, so that the peripheral edges around the screen are relatively small to make the overall flat display panel compact.  
      However, making the frame according to an integral forming process such as an aluminum die-casting process requires special dedicated dies and is time-consuming.  
     SUMMARY OF THE INVENTION  
      It is therefore an object of the present invention to provide a frame assembly having a frame having a certain width along the depth, which can easily be manufactured as an aluminum extrusion, the frame assembly including corners assembled essentially free of positional misalignments and having fastening screws and rivets concealed from external view.  
      According to the present invention, there is provided a frame assembly including an outer frame having upper, lower, left, and right side plates, an inner frame disposed in the outer frame, and a plurality of holders applied to inner surfaces of the upper, lower, left, and right side plates of the outer frame, for fixedly holding the upper, lower, left, and right side plates of the outer frame within the inner frame, wherein the outer frame has a plurality of corners, and the upper and lower side plates of the outer frame and the left and right side plates of the outer frame are interfitted in the corners.  
      With the above frame assembly, even if the outer frame is made of aluminum and has a certain width along its depth, the outer frame can easily be manufactured by an extrusion molding process rather than an aluminum die-casting process using dies.  
      In the corners of the outer frame, the upper side plate and the left side plate, the upper side plate and the right side plate, the lower side plate and the left side plate, and the lower side plate and the right side plate are interfitted without undue positional misalignments.  
      The upper, lower, left, and right side plates of the outer frame are fixedly held in the inner frame by the holders applied to the inner surfaces of the side plates. The holders and fastening screws and rivets are concealed from external view outside of the corners. Because the holders and fastening screws and rivets are concealed from external view, and also because the upper and lower side plates of the outer frame and the left and right side plates of the outer frame are interfitted in the corners, the frame assembly has an excellent appearance.  
      The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate a preferred embodiment of the present invention by way of example. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a front elevational view of a liquid crystal display panel device as an electronic device according to the present invention;  
       FIG. 2  is a front elevational view of a frame assembly, with an inner frame omitted from illustration, according to the present invention;  
       FIGS. 3A, 3B , and  3 C are views showing outer, side, and inner surfaces, respectively, of each of outer frame upper and lower side plates;  
       FIGS. 4A, 4B , and  4 C are views showing outer, side, and inner surfaces, respectively, of each of outer frame left and right side plates;  
       FIG. 5  is a cross-sectional view taken along line F 5 -F 5  of  FIGS. 3A, 3B , and  3 C and  FIGS. 4A, 4B , and  4 C;  
       FIG. 6  is a cross-sectional view showing the definition of ribs in the cross-sectional structure shown in  FIG. 5 ;  
       FIG. 7  is a perspective view of an inner frame of the frame assembly;  
       FIGS. 8A and 8B  are exploded perspective and perspective views, respectively, of an upper side portion of the frame assembly;  
       FIGS. 9A and 9B  are exploded perspective and perspective views, respectively, of a left side portion of the frame assembly;  
       FIGS. 10A and 10B  are views showing front side and inner surfaces, respectively, of a right end portion of the outer frame upper side plate;  
       FIGS. 11A and 11B  are views showing front side and inner surfaces, respectively, of a corner bracket;  
       FIGS. 12A, 12B , and  12 C are views showing the manner in which the corner bracket is press-fitted into the right end portion of the outer frame upper side plate;  
       FIGS. 13A and 13B  are views showing the manner in which the corner bracket is press-fitted into the right end portion of the outer frame upper side plate;  
       FIG. 14  is a cross-sectional view showing how components of an upper right corner of the frame assembly are assembled; and  
       FIG. 15  is a perspective view showing how components of the upper right corner of the frame assembly are interfitted. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       FIG. 1  shows an electronic device according to the present invention, which incorporates a frame assembly according to the present invention. In  FIG. 1 , the electronic device includes a liquid crystal display panel device.  
      As shown in  FIG. 1 , the liquid crystal display panel device includes a frame assembly  10  and a liquid crystal display panel  20 , and is mounted on a stand  51 .  
      The frame assembly  10  includes an outer frame  100 , an inner frame (cabinet) that is omitted from illustration in  FIG. 1 , a transparent upper side plate  210 , a transparent lower side plate  220 , a transparent left side plate  230 , and a transparent right side plate  240 . The outer frame  100  has upper left, upper right, lower left, and lower right corners combined with respective corner covers  510 ,  520 ,  530 ,  540 .  
      The transparent upper side plate  210 , the transparent lower side plate  220 , the transparent left side plate  230 , and the transparent right side plate  240  serve to create a floating effect which makes the display screen of the liquid crystal display panel  20  look floating in the air by making a wall behind the liquid crystal display panel device visible through the transparent upper side plate  210 , the transparent lower side plate  220 , the transparent left side plate  230 , and the transparent right side plate  240 .  
      The liquid crystal display panel  20  is mounted in the inner frame, and has a liquid crystal display unit, a backlight, and a circuit and a power supply for energizing the liquid crystal display unit and the backlight.  
      The display screen of the liquid crystal display panel  20  has peripheral edges spaced inwardly from the inner edges of the transparent upper side plate  210 , the transparent lower side plate  220 , the transparent left side plate  230 , and the transparent right side plate  240 . The space between the peripheral edges of the display screen and the inner edges of the side plates  210 ,  220 ,  230 ,  240  is covered with a front mask  890  for concealing an inner structure of the liquid crystal display panel device.  
      The front mask  890  has a number of small circular holes (not shown) defined in each of the areas thereof which are aligned with respective left and right speakers of the liquid crystal display panel device.  
      In the description which follows, the terms “vertical”, “upper”, “lower”, “horizontal”, “left”, and “right”, etc. are used with respect to the display screen of the liquid crystal display panel  20  as shown in  FIG. 1 , and the term “depth” is used to represent a direction normal to the display screen, i.e., the sheet of  FIG. 1 . The terms “inward”, “inner”, “outward”, and “outer”, etc. are used with respect to the geometric center of the display screen. The terms “forward” and “front” are used to represent a direction toward the viewer of  FIG. 1 , and the terms “rearward” and “rear” are used to represent a direction away from the viewer of  FIG. 1 .  
       FIG. 2  shows the frame assembly  10 , with the inner frame omitted from illustration.  
      As shown in  FIG. 2 , the outer frame  100  of the frame assembly  10  includes an outer frame upper side plate  110 , an outer frame lower side plate  120 , an outer frame left side plate  130 , and an outer frame right side plate  140 .  
      The outer frame upper side plate  110 , the outer frame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140  are in the form of aluminum extrusions having identical cross-sectional shapes.  
       FIGS. 3A, 3B , and  3 C show outer, side (front or rear), and inner surfaces, respectively, of each of the outer frame upper and lower side plates  110 ,  120 .  FIGS. 4A, 4B , and  4 C show outer, side (front or rear), and inner surfaces, respectively, of each of the outer frame left and right side plates  130 ,  140 .  FIG. 5  shows a cross-sectional shape of each of the outer frame upper side plate  110 , the outer frame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140 , the view being taken along line F 5 -F 5  of  FIGS. 3A, 3B , and  3 C and  FIGS. 4A, 4B , and  4 C.  FIG. 6  shows the definition of ribs and a base surface of each of the outer frame upper side plate  110 , the outer frame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140 .  
      The leftward direction of the outer frame upper side plate  110  shown in  FIGS. 3A, 3B , and  3 C is the same as the leftward direction of the display screen, and the right direction of the outer frame lower side plate  120  shown in  FIGS. 3A, 3B , and  3 C is the same as the leftward direction of the display screen. The leftward direction of the outer frame left side plate  130  shown in  FIGS. 4A, 4B , and  4 C is the same as the upward direction of the display screen, and the right direction of the outer frame right side plate  140  shown in  FIGS. 4A, 4B , and  4 C is the same as the upward direction of the display screen.  
      The inner surface of each of the outer frame upper side plate  110 , the outer frame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140  which are extrusion-molded has ribs R 1 , R 2 , R 3 , R 4 , R 5 , F 6 , R 7 , and F 8  that are integrally formed symmetrically in transverse and longitudinal directions of the side plates. As shown in  FIG. 5 , each of the outer frame upper side plate  110 , the outer frame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140  has slits  3   e ,  3   f ,  3   g  defined parallel to each other in the transverse direction of the side plates.  
      The ribs R 1 , R 2 , R 4 , R 4  have respective inner surfaces  1   a ,  1   b ,  1   c ,  1   d  lying flush with each other, and the slits  3   e ,  3   f ,  3   g  are defined by respective surfaces  2   e ,  2   f ,  2   g  lying flush with each other as a base surface  2 .  
      As shown in  FIG. 5 , the slits  3   f ,  3   g  which are positioned on opposite sides on the slit  3   e  have opposite end portions represented by a gap t 1  and a central portion represented by a gap t 2 , the gap t 1  being smaller than the gap t 2 .  
      As indicated by the two-dot-and-dash lines in  FIG. 5 , the transparent upper side plate  210 , the transparent lower side plate  220 , the transparent left side plate  230 , and the transparent right side plate  240  are applied by double-faced adhesive tapes to the inner surfaces  1   a ,  1   b ,  1   c ,  1   d , which lie flush with each other, of the outer frame upper side plate  110 , the outer frame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140 , as described later.  
      As shown in  FIGS. 3A, 3B , and  3 C, each of the outer frame upper side plate  110  and the outer frame lower side plate  120  has opposite ends, i.e., left and right ends, where the ribs R 1  through R 6  on their inner surfaces are partly cut off into flat surfaces  2   h  as part of the base surface  2 , and grooves  115  are formed in the respective flat surfaces  2   h  along the width of the side plates  110 ,  120 , by a machining process that is performed after the side plates  110 ,  120  are extrusion-molded.  
      Slanted recesses  112   a  are formed in the left and right ends of the ribs R 7  of each of the outer frame upper side plate  110  and the outer frame lower side plate  120 , and similar slanted recesses are also formed in the left and right ends of the ribs R 8  of each of the outer frame upper side plate  110  and the outer frame lower side plate  120 , by a machining process that is performed after the side plates  110 ,  120  are extrusion-molded.  
      As shown in  FIGS. 4A, 4B , and  4 C, each of the outer frame left side plate  130  and the outer frame right side plate  140  has opposite ends, i.e., upper and lower ends, where the ribs R 1  through R 6  on their inner surfaces are partly cut off into flat surfaces  2   h  as part of the base surface  2 , and ridges  144  are formed on the ends of the flat surfaces  2   h  for fitting engagement in the grooves  115  in the outer frame upper side plate  110  and the outer frame lower side plate  120 , by a machining process that is performed after the side plates  130 ,  140  are extrusion-molded.  
      Slanted lands  142   a  are formed on the upper and lower ends of the ribs R 7  of each of the outer frame left side plate  130  and the outer frame right side plate  140  for abutting engagement in the slanted recesses  112   a  of the outer frame upper side plate  110  and the outer frame lower side plate  120 , and similar slanted lands are formed on the upper and lower ends of the ribs R 8  of each of the outer frame left side plate  130  and the outer frame right side plate  140 , by a machining process that is performed after the side plates  130 ,  140  are extrusion-molded.  
      As shown in  FIGS. 1, 2 , and  5 , as described above, the transparent upper side plate  210 , the transparent lower side plate  220 , the transparent left side plate  230 , and the transparent right side plate  240  are applied by double-faced adhesive tapes to the inner surfaces  1   a ,  1   b ,  1   c ,  1   d  of the outer frame upper side plate  110 , the outer frame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140 , as described later.  
      The transparent upper side plate  210 , the transparent lower side plate  220 , the transparent left side plate  230 , and the transparent right side plate  240  are formed as acrylic or polycarbonate plates. As shown in  FIG. 5 , each of the transparent upper side plate  210 , the transparent lower side plate  220 , the transparent left side plate  230 , and the transparent right side plate  240  has a thickness d of about 10 mm in the vertical or horizontal direction and a width w of about several cm or greater along the depth, i.e., in the front-to-rear direction. Therefore, the width w is greater than the thickness d.  
      As shown in  FIG. 2 , holders  610 ,  620 ,  630  are applied by double-faced adhesive tapes respectively to left, right, and central regions of the inner surface of the transparent upper side plate  210 .  
      Holders  650 ,  660 ,  670  are applied by double-faced adhesive tapes respectively to left, right, and central regions of the inner surface of the transparent upper side plate  220 .  
      Similarly, holders  710 ,  720 ,  730  are applied by double-faced adhesive tapes respectively to upper, lower, and central regions of the inner surface of the transparent left side plate  230 , and holders  750 ,  760 ,  770  are applied by double-faced adhesive tapes respectively to upper, lower, and central regions of the inner surface of the transparent right side plate  240 .  
      The holders are in the form of metal plates. The holder  610  has lugs  611 ,  612 ,  613 ,  614  integrally formed with an inner surface thereof. The holder  620  has lugs  621 ,  622 ,  623 ,  624  integrally formed with an inner surface thereof. The holder  630  has lugs  631 ,  633  integrally formed with an inner surface thereof. These lugs serve to attach the outer frame upper side plate  110 , the outer frame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140 , i.e., the outer frame  100 , to the inner frame. When the lugs are fastened to the inner frame by screws, the outer frame  100  and the inner frame are joined to each other, providing the frame assembly  10 .  
       FIG. 7  shows the inner frame, generally denoted by  900 . The inner frame  900  includes an inner frame main body  950  having an inner frame upper side plate  910 , an inner frame lower side plate  920 , an inner frame left side plate  930 , and an inner frame right side plate  940 , and an inner frame front face  960 . The inner frame  900  is integrally molded of plastics.  
      The inner frame main body  950  has threaded holes  970  defined in inner surfaces thereof for receiving the screws by which the lugs of the holders described above are fastened. The inner frame front face  960  has through holes  980  defined in left and right plates thereof for housing speakers therein.  
      The outer frame  100 , to which the transparent upper side plate  210 , the transparent lower side plate  220 , the transparent left side plate  230 , and the transparent right side plate  240  are applied, is mounted on the inner frame  900 .  
       FIGS. 8A and 8B  show an upper side portion of the outer frame  100 . As shown in  FIG. 8A , the transparent upper side plate  210  has left and right end faces  211 ,  212  (not shown in  FIGS. 1 and 2 ) formed as slanted surfaces inclined at  450  to the horizontal and vertical directions and having a mirror finish.  
      The holders  610 ,  620 ,  630  are applied to the inner surface of the transparent upper side plate  210  by double-faced adhesive tapes. The transparent upper side plate  210  to which the holders  610 ,  620 ,  630  are applied is applied to the inner surface of the outer frame upper side plate  110  by a double-faced adhesive tape.  
      Before the double-faced adhesive tapes are applied, thin mirror-finish films are printed on the inner and outer surfaces of the transparent upper side plate  210 , so that the double-faced adhesive tapes on the inner and outer surfaces of the transparent upper side plate  210  will invisible from the front side in the assembled state shown in  FIG. 8B .  
      Other components of the upper side portion of the outer frame  100  include a corner bracket  310 , a corner joint  410 , and a corner cover  510  for assembling an upper left corner  11  shown in  FIG. 2 , and a corner bracket  320 , a corner joint  420 , and a corner cover  520  for assembling an upper right corner  12  shown in  FIG. 2 .  
      The outer frame  100  has a lower side portion which is of a structure similar to the upper side portion thereof except that they are vertically symmetrical.  
       FIGS. 9A and 9B  show a left side portion of the outer frame  100 . As shown in  FIG. 9A , the transparent left side plate  230  has upper and lower end faces  231 ,  232  (not shown in  FIGS. 1 and 2 ) formed as slanted surfaces inclined at  450  to the horizontal and vertical directions and having a mirror finish.  
      The holders  710 ,  720 ,  730  are applied to the inner surface of the transparent left side plate  230  by double-faced adhesive tapes. The transparent left side plate  230  to which the holders  710 ,  720 ,  730  are applied is applied to the inner surface of the outer frame left side plate  130  by a double-faced adhesive tape.  
      Before the double-faced adhesive tapes are applied, thin mirror-finish films are printed on the inner and outer surfaces of the transparent left side plate  230 , so that the double-faced adhesive tapes on the inner and outer surfaces of the transparent left side plate  230  will be invisible from the front side in the assembled state shown in  FIG. 9B .  
      The outer frame  100  has a right side portion which is of a structure similar to the left side portion thereof except that they are horizontally symmetrical.  
       FIGS. 10A and 10B  show a right end portion of the outer frame upper side plate  110 .  FIG. 10A  shows a front side of the right end portion of the outer frame upper side plate  110 , and  FIG. 10B  shows an inner surface of the right end portion of the outer frame upper side plate  110 .  
      The slanted recess  112   a  also shown in  FIGS. 3B and 3C  is formed in the right end of a front end  112  that is provided by the rib R 7  of the outer frame upper side plate  110  shown in  FIGS. 3C and 6 , and the slanted recess  113   a  is formed in the right end of a rear end  113  that is provided by the rib R 8  shown in  FIGS. 3C and 6 .  
      Fitting ribs  112   b ,  113   b  are formed, respectively adjacent to the slanted recesses  112   a ,  113   a , on the right ends of the ribs R 5 , R 6  of the outer frame upper side plate  110  shown in  FIGS. 3C and 6 , by a machining process.  
      The inner flat surface  2   h  on the right end of the outer frame upper side plate  110  is part of the base surface  2 , as described above. The groove  115  extending along the width of the outer frame upper side plate  110 , as also shown in  FIG. 3C , is formed in a right end portion of the inner flat surface  2   h  at a position slightly spaced from a right end face  114  of the outer frame upper side plate  110 .  
      The rib R 3  is cut off a predetermined length from the right end face  114 , providing an engaging plate  116  integral with a portion of the base surface  2  of the outer frame upper side plate  110  which is close to the front end  112 . The rib R 4  is also cut off a predetermined length from the right end face  114 , providing an engaging plate  117  integral with a portion of the base surface  2  of the outer frame upper side plate  110  which is close to the rear end  113 .  
      The ribs R 1 , R 2  are cut off a length, which is greater than the above predetermined lengths from the right end face  114 , providing engaging plates  118 ,  119  integral with a central portion of the base surface  2  along the width of the outer frame upper side plate  110 .  
      The slit  3   f  shown in  FIG. 5  is formed between the engaging plates  116 ,  118  and the surface  2   f . The slit  3   g  shown in  FIG. 5  is formed between the engaging plates  117 ,  119  and the surface  2   g . The slit  3   e  is formed between the engaging plates  118 ,  119  and the surface  2   e.    
      The left end portion of the outer frame upper side plate  110  is similar to the right end portion thereof except that they are horizontally symmetrical. The outer frame lower side plate  120  has a left end portion which is similar to the left end portion of the outer frame upper side plate  110  except that they are vertically symmetrical. The outer frame lower side plate  120  has a right end portion which is similar to the right end portion of the outer frame upper side plate  110  except that they are vertically symmetrical, i.e., which is similar to the left end portion of the outer frame lower side plate  120  except that they are horizontally symmetrical.  
       FIGS. 11A and 11B  show the corner bracket  320  for use on the right end portion of the outer frame upper side plate  110  shown in  FIGS. 8A and 8B .  FIG. 11A  shows a front side of the corner bracket  320 , and  FIG. 11B  shows an inner surface of the corner bracket  320 .  
      The corner bracket  320  includes an upper side plate  321  for extending along the right end of the outer frame upper side plate  110  and a right side plate  327  integrally joined perpendicularly to the upper side plate  321  for extending along the upper end of the outer frame right side plate  140 .  
      The upper side plate  321  has two spaced legs  322 ,  323  disposed on front and rear sides thereof, and an engaging edge  326 , described later, disposed between the legs  322 ,  323  at right ends thereof.  
      The upper side plate  321  also has two spaced engaging fingers  324 ,  325  on each of front and rear edges thereof.  
      The corner bracket  310  for use on the left end of the outer frame upper side plate  110  shown in  FIGS. 8A and 8B  is similar to the above corner bracket  320  except that they are horizontally symmetrical. Corner brackets for use on the left and right ends, respectively, of the outer frame lower side plate  120  are similar to the corner brackets  310 ,  320  except that they are vertically symmetrical.  
      Before the corners  11 ,  12 ,  13 ,  14  are assembled, components of the frame assembly  10  are assembled as follows:  
      (1) First, double-faced adhesive tapes are applied to the inner surfaces of the outer frame upper side plate  110 , the outer frame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140 .  
      (2) Then, double-faced adhesive tapes are applied to the holders  610 ,  620 ,  630 ,  650 ,  660 ,  670 ,  710 ,  720 ,  730 ,  750 ,  760 , and  770  shown in  FIG. 2 .  
      (3) Thereafter, the holders  610 ,  620 ,  630  are applied to the transparent upper side plate  210 , the holders  650 ,  660 ,  670  to the transparent lower side plate  220 , the holders  710 ,  720 ,  730  to the transparent left side plate  230 , and the holders  750 ,  760 ,  770  to the transparent right side plate  240 .  
      (4) Then, the transparent upper side plate  210  is applied to the inner surface of the outer frame upper side plate  110 , the transparent lower side plate  220  to the inner surface of the outer frame lower side plate  120 , the transparent left side plate  230  to the inner surface of the outer frame left side plate  130 , and the transparent right side plate  240  to the inner surface of the outer frame right side plate  140 .  
      Thereafter, the corners  11 ,  12  of the outer frame upper side plate  110  and the corners  13 ,  14  of the outer frame lower side plate  120  are assembled as follows:  
      First, the corner  11  of the outer frame upper side plate  110  is assembled as follows: The corner cover  520  shown in  FIG. 8A  is applied to the corner cover  420 , and then the corner joint  420  is inserted into the right end of the outer frame upper side plate  110 .  
      Then, as shown in  FIG. 12A , the engaging fingers  324 ,  325  of the upper side plate  321  of the corner bracket  320  are bent inwardly. As indicated by the arrow  328  in  FIG. 12B , the upper side plate  321  of the corner bracket  320  is inserted between the engaging plates  116 ,  117  and the base surface  2  of the right end of the outer frame upper side plate  110 . The corner cover  520  and the corner joint  420  are omitted from illustration in  FIGS. 12B and 12C .  
      As shown in  FIG. 13A , the engaging plates  116 ,  117  have portions closer to the front end  112  and the rear end  113 , respectively, the portions providing a relatively low roof at the gap t 1 . The engaging plates  116 ,  117  also have portions extending closely to the engaging plates  118 ,  119 , the portions providing a relatively high roof at the gap t 2 .  
      As shown in  FIG. 13A , an outer horizontal plate  421 , described later, of the corner joint  420  is inserted into relatively narrow inner portions of the gap t 2 , and the legs  322 ,  323  of the upper side plate  321  of the corner bracket  320  are superposed on the outer lateral plates  421  and inserted into the relatively wide gap t 1 .  
      At this time, as shown in  FIGS. 12C and 13B , the upper side plate  321  of the corner bracket  320  is pressed into a position where the engaging edge  326  between the legs  322 ,  323  abuts against the engaging plates  118 ,  119  and the right side plate  327  covers a portion of the groove  115 .  
      With the corner bracket  320  pressed into the right end of the outer frame upper side plate  110 , even when an attempt is made to pull the corner bracket  320  from the right end of the outer frame upper side plate  110  as indicated by the arrow  329  in  FIG. 12B , the engaging fingers  324 ,  325  bite into the low roof of the engaging plates  116 ,  117  near the front end  112  and the rear end  113 , and hence the corner bracket  320  cannot be pulled out.  
      Therefore, after the corner cover  520 , the corner joint  420 , and the corner bracket  320  are assembled on the right end of the outer frame upper side plate  110 , they remain assembled unless an emergency measure is taken, e.g., unless the assembly itself is broken.  
       FIG. 14  shows how the components of the upper right corner  12  are assembled. The corner joint  420  includes an integral structure including an outer horizontal plate  421 , an outer vertical plate  422 , an inner horizontal plate  423 , an inner vertical plate  424 , and a joint plate  425 . The outer horizontal plate  421  has two legs, as with the upper side plate  321  of the corner bracket  320  shown in  FIGS. 11A, 11B ,  12 A,  12 B,  12 C,  13 A, and  13 B.  
      As shown in  FIG. 13A , the width of the corner joint  420  along the depth of the outer frame  100  in the horizontal direction in  FIGS. 13A, 13B  or the direction normal to the sheet of  FIG. 14  is smaller than the width of the corner bracket  320  along the depth of the outer frame  100 .  
      The corner cover  520  of the upper right corner  12  has a corner cover base  523  and two end plates  521  integrally formed with the opposite ends of the corner cover base  523  along the depth, i.e., in the direction normal to the sheet of  FIG. 14 , the end plates  521  being shaped to cover the right end of the transparent upper side plate  210  and the upper end of the transparent right side plate  240 , as indicated by the two-dot-and-dash lines in  FIG. 14 . In  FIGS. 1 and 2 , the front end plate of the corner cover  520  is shown.  
      The upper right corner  12  is assembled as follows: As shown in  FIG. 14 , the corner cover base  523  is applied to the joint plate  425  by a double-faced adhesive tape  820 , thereby mounting the corner cover  520  on the corner joint  420 .  
      Then, the outer horizontal plate  421  of the corner joint  420  on which the corner cover  520  is mounted is inserted into the right end of the outer frame upper side plate  110 , to which the transparent upper side plate  210  with the holder  620  applied thereto by the double-faced adhesive tape  812  is applied by the double-faced adhesive tape  811 , until the outer horizontal plate  421  abuts against the engaging plates  118 ,  119  shown in  FIGS. 12C and 13B .  
      At this time, the inner horizontal plate  423  of the corner joint  420  functions to support the inner surface, where the double-sided adhesive tape  812  is not applied, of a plate  625  of the holder  620  along the transparent upper side plate  210 .  
      At this time, the transparent upper side plate  240  with the holder  750  applied thereto by the double-faced adhesive tape  814  is applied to the outer frame right side plate  140  by the double-faced adhesive tape  813 .  
      The holder  620  has the lug  622  disposed on the inner surface of the plate  625 , and the holder  750  also has a lug  752  on a plate  755  thereof.  
      After the corner joint  420  is thus inserted into the right end of the outer frame upper side plate  110 , the corner bracket  320  is pressed into the right end of the outer frame upper side plate  110 , as described above with reference to  FIGS. 12A, 12B ,  12 C,  13 A, and  13 B.  
      The upper right corner  12  of the outer frame upper side plate  110  has now been assembled. When the upper left corner  11  of the outer frame upper side plate  110  has been assembled, the upper side portion of the frame assembly  10  is assembled as shown in  FIG. 8B .  
      The outer fame lower side plate  120  is assembled in the same manner as with the outer frame upper side plate  110 .  
      The outer frame upper side plate  110 , the outer fame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140  thus assembled are assembled onto the inner frame  900  as follows:  
      First, the outer frame left side plate  130  and the outer frame right side plate  140  are installed on the inner frame  900 . At this time, the lugs of the holders on the outer frame left side plate  130  and the outer frame right side plate  140  are inserted into slits, not shown, in the inner frame main body  950 , and fastened thereto by screws threaded into the threaded holes  970  shown in  FIG. 7 . In this manner, the outer frame left side plate  130  and the outer frame right side plate  140  are thus mounted on the inner frame  900 .  
      Then, the corners  11 ,  12 ,  13 ,  14  are put together, and the lugs of the holders on the outer frame upper side plate  110  and the outer fame lower side plate  120  are inserted into slits, not shown, in the inner frame main body  950 , and fastened thereto by screws threaded into the threaded holes  970  shown in  FIG. 7 . In this manner, the outer frame upper side plate  110  and the outer fame lower side plate  120  are thus mounted on the inner frame  900 .  
      In the upper right corner  12 , as shown in  FIG. 14 , the outer vertical plate  422  of the corner joint  420  and the right side plate  327  of the corner bracket  320  are inserted into the upper end of the outer frame right side plate  140 , and the outer frame right side plate  140 , the transparent right side plate  240 , and the holder  750  which are integrally combined by the double-sided adhesive tapes  814 ,  813  are sandwiched by the outer vertical plate  422  and the inner vertical plate  424  of the corner joint  420 . The upper left corner  11 , the lower left corner  13 , and the lower right corner  14  are of a similar construction.  
       FIG. 15  shows how the outer frame upper side plate  110  and the outer frame right side plate  140  are interfitted.  
      The front side of the upper end of the outer frame right side plate  140  has the slanted lands  142   a  shown in  FIGS. 4B and 4C  which are fitted in the slanted recesses  112   a  in the outer frame upper side plate  110  shown in  FIGS. 3A, 3B ,  3 C,  10 A, and  10 B. The rear side of the upper end of the outer frame right side plate  140  also has the slanted lands fitted in the slanted recesses  113   a  in the outer frame upper side plate  110  shown in  FIGS. 10A and 10B .  
      The upper end of the outer frame right side plate  140  has the ridge  144  shown in  FIGS. 4B and 4C  which is fitted in the groove  115  in the outer frame upper side plate  110  shown in  FIGS. 3A, 3B ,  3 C,  10 B,  12 C, and  13 B. As shown in  FIG. 15 , the outer frame right side plate  140  has upper end engaging teeth  144   x ,  144   y  disposed on the right surface of the upper end thereof, the upper end engaging teeth  144   x ,  144   y  being positioned respectively near the front and rear sides of the outer frame right side plate  140 .  
      After the corner bracket  320  is pressed into the right end of the outer frame upper side plate  110 , the ridge  144  on the upper end of the outer frame right side plate  140  is inserted into the groove  115  in the right end of the outer frame upper side plate  110 . The outer frame right side plate  140  and the outer frame upper side plate  110  are interfitted until the slanted lands  142   a  on the front side of the outer frame right side plate  140  are brought into abutting engagement in the slanted recesses  112   a  in the outer frame upper side plate  110 , the slanted lands on the rear side of the outer frame right side plate  140  are brought into abutting engagement in the slanted recesses  113   a  in the outer frame upper side plate  110 , and the right end face  114  of the outer frame upper side plate  110  is fitted between the upper end engaging teeth  144   x ,  144   y  of the outer frame right side plate  140 .  
      The upper right corner  12  is thus assembled by interfitting the outer frame upper side plate  110  and the outer frame right side plate  140 , without the need for screws and rivets, and hence is of excellent appearance.  
      The upper left corner  11 , the lower left corner  13 , and the lower right corner  14  are assembled in the same manner as described above.  
      With the frame assembly  10  thus assembled, the outer frame upper side plate  110  and the outer frame right side plate  140  in the upper right corner  12  are essentially free of any positional misalignments in the horizontal and vertical directions and along the depth, i.e., in the front-to-rear direction. The outer frame upper side plate  110  and the outer frame left side plate  130  in the upper left corner  11 , the outer frame lower side plate  120  and the outer frame left side plate  130  in the lower left corner  13 , and the outer frame lower side plate  120  and the outer frame right side plate  140  in the lower right corner  14  are also essentially free of any positional misalignments in those directions.  
      In the upper right corner  12 , as shown in  FIG. 15 , the slanted right end face  212  of the transparent upper side plate  210  and a slanted upper end face  241  of the transparent right side plate  240  are concealed by the end plate  521  of the corner cover  520 . Therefore, even if the transparent upper side plate  210  and the transparent right side plate  240  suffer manufacturing errors or are installed with positional errors, the right end of the transparent upper side plate  210  and the upper end of the transparent right side plate  240  in the upper right corner  12  are invisible, keeping the frame assembly  10  in good quality.  
      The inner and outer surfaces of the transparent upper side plate  210  and the upper end of the transparent right side plate  240 , to which the double-sided adhesive taps  812 ,  811  or the double-sided adhesive taps  814 ,  813  are applied, have mirror-finish films printed thereon, and the slanted right end face  212  of the transparent upper side plate  210  and the slanted upper end face  241  of the transparent right side plate  240  are processed into a mirror finish. Therefore, even when the rear side of the corner cover  520  is seen obliquely, the components that make up the frame assembly  10  and the structure thereof are not visible at all. This effect, together with the floating effect referred to above, gives a beautiful appearance to the frame assembly  10  and the liquid crystal display panel device incorporating the frame assembly  10  therein.  
      The same beautiful appearance is given to the upper left corner  11 , the lower left corner  13 , and the lower right corner  14 , and also to the frame assembly  10  in its entirety.  
      The outer frame upper side plate  110 , the transparent upper side plate  210 , and the holders  610 ,  620 ,  630  shown in  FIG. 2  are put together by several double-faced adhesive tapes including the double-faced adhesive tapes  812 ,  811 , and the innermost holders  610 ,  620 ,  630  are fixed to the threaded holes  970  of the inner frame  900  shown in  FIG. 7 . Therefore, when strong external forces are exerted to the outer frame upper side plate  110 , or due to aging, the components put together by the double-faced adhesive tapes may possibly be peeled off.  
      However, since the corner joints  410 ,  420  shown in  FIGS. 8A and 8B  firmly retain the outer frame upper side plate  110 , the transparent upper side plate  210 , and the holders  610 ,  620  integrally together, the components are not liable to be peeled off. Therefore, when the outer frame upper side plate  110  is attracted by a lifter and the frame assembly  10  or the liquid crystal display panel device incorporating the frame assembly  10  is moved, no problem arises in attracting the outer frame upper side plate  110  with the lifter or moving the frame assembly  10  or the liquid crystal display panel device incorporating the frame assembly  10 .  
      In the above embodiment, the transparent upper side plate  210 , the transparent lower side plate  220 , the transparent left side plate  230 , and the transparent right side plate  240  are employed to create a floating effect which makes the display screen of the liquid crystal display panel  20  look floating in the air. If such a floating effect is not required, then other boards may be employed in place of the transparent upper side plate  210 , the transparent lower side plate  220 , the transparent left side plate  230 , and the transparent right side plate  240 .  
      Alternatively, no boards may be interposed between the outer frame  100  and the inner frame  900 , and the outer frame upper side plate  110 , the outer frame lower side plate  120 , the outer frame left side plate  130 , and the outer frame right side plate  140  may be installed on the inner frame  900  by holders that are applied to those side plates.  
      In the above embodiment, the present invention is applied to a liquid crystal display panel device. However, the principles of the present invention are also applicable to any of various other flat display panel devices such as a plasma display panel device, or any of various other electronic devices other than flat display panel devices.  
      Although a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.