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BACKGROUND OF THE INVENTION 
     The invention relates to suspended ceiling constructions and, in particular, to a type of suspended ceiling having a panel supporting grid and associated panels arranged such that the grid is largely concealed by the panels. 
     PRIOR ART 
     Various systems have been proposed to provide a concealed grid suspends an array of rectangular removable ceiling panels. In general, such prior art systems have had one or more disadvantages and there remains the need for a versatile system that can be readily manufactured and installed and which provides a high quality appearance. Commonly, in these systems, the panels are formed with intricate edge details which can be difficult to manufacture, are relatively fragile, and are prone to become damaged with even moderate mishandling. Moreover, these prior art panels are often of limited stability and can be dislodged and even dropped when subjected to an accidental blow. 
     SUMMARY OF THE INVENTION 
     The invention provides a suspended ceiling construction with an improved appearance that is derived from a suspension grid that is largely concealed by the ceiling panels. More specifically, the visual effect of the ceiling is dramatically improved by the diminished exposure and recessing of the grid between the panels. The construction utilizes a combination of a metal clip attached to a panel and a grid member with an upstanding flange portion that is engaged by the clip. The clip accurately and positively locates its associated panel relative to the grid and prevents it from accidentally shifting horizontally out of its proper location. The precise locating action obtained by the clip and flange combination permits the panels to be constructed in such a way that only a relatively small aesthetically pleasing gap exists between adjacent panels. Since the panels are accurately located, there is no noticeable variation in the gaps between panels. 
     The invention can be practiced in a variety of grid and panel designs providing for either upward or downward access. In the preferred embodiment, all of the grid members have the same “W” flange configuration so that square panels can be assembled in any of four positions, i.e. turned 360° about a vertical axis making them readily adaptable to all edge conditions. The uniform grid geometry, in addition, simplifies the mounting of accessories such as lights and air diffusers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a somewhat diagrammatic fragmentary perspective upward view of a suspended ceiling system constructed in accordance with the invention; 
     FIG. 2 is a cross-sectional view of a grid tee member used in the grid of the ceiling system of FIG. 1; 
     FIG. 3 is a side view of one form of a ceiling panel clip of the invention; 
     FIG. 4 is a top view of the panel clip; 
     FIG. 5 is a bottom view of the panel clip; 
     FIG. 6 is an end view of the panel clip; 
     FIG. 7 is a cross-sectional view of the ceiling system taken in the plane indicated at  7 — 7  in FIG. 1; 
     FIG. 8 is a cross-sectional view of the ceiling system taken in the plane indicated at  8 — 8  in FIG. 1; 
     FIG. 9 is a view similar to FIG. 7 showing how access to the space above the ceiling system is achieved with downward panel removal; 
     FIG. 10 is a cross-sectional view in a plane similar to that of FIG. 7, of a modified ceiling system; 
     FIG. 11 is a cross-sectional view in a plane similar to that of FIG. 8, of the ceiling system of FIG. 10; 
     FIG. 12 is a view similar to FIG. 10, showing the removal of a panel with downward access; 
     FIG. 13 is a cross-sectional view in a plane similar to that of FIG. 7, showing a third variation of a ceiling system; 
     FIG. 14 is a cross-sectional view in a plane similar to that of FIG. 8, of the system of FIG. 13; 
     FIG. 15 is a cross-sectional view in a plane similar to that of FIG. 7, showing a fourth variation of a ceiling system; 
     FIG. 16 is a cross-sectional view in a plane similar to that of FIG. 8, showing the system of FIG. 15; 
     FIG. 17 is an end view of a clip used in the embodiments shown in FIGS. 13 and 15; 
     FIG. 18 is a cross-sectional view in a plane similar to that of FIG. 7 of another modified ceiling system; 
     FIG. 19 is a cross-sectional view in a plane similar to that of FIG. 8 of the ceiling system of FIG. 18; and 
     FIG. 20 is a view similar to FIG. 18 showing the removal of a panel with downward access. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIGS. 1 through 9, a suspended ceiling system  10  embodying a first version of the invention, comprises a suspension grid  11  and removable panels  12 . While the illustrated grid  11  forms square openings and the panels  12  are square, the invention is applicable to rectangular patterns. For convenience, when the term “rectangular” is used herein, it will be understood that such term includes square shapes. In a conventional manner, the grid  11  includes main runners or tees  13  of extended length and cross runners or tees  14 ,  15  of limited length. Certain cross runners  14  are nominally four foot long and certain other cross runners  15  are nominally two foot long. The main runner and cross runner patterns of the grid constructions of other embodiments discussed below can be the same as described here in connection with FIGS. 1 through 9. Alternatively, the invention can be practiced with other known grid patterns such as a basket weave pattern. 
     In the first embodiment or version of the invention shown in FIGS. 1 through 9, the main and cross runners  13 ,  14  and  15 , respectively, have the same general configuration which is depicted on an enlarged scale in FIG.  2 . In this and in the other embodiments disclosed herein, the main runner  13 , as is conventional, can be taller and/or be constructed of heavy gauge material for suitable load capacity. The runners  13 ,  14  and  15  are in the general form of an inverted tee and, with reference to their flange area, can be described as having a W-shaped configuration. These runners or tees  13 ,  14  and  15 , have a hollow upper stiffening bulb  16 , a vertical double web  17 , and oppositely extending flanges  18 . Preferably, the tee is formed, typically by a rolling process known in the art, so that the bulb  16 , web  17  and flanges  18  are all integral and the web has a double wall. As illustrated, the flanges  18  include a covering or cap  19  of sheet metal rolled or otherwise bent onto the flanges  18 . The cap  19  can have its exterior surface painted a suitable color or be otherwise finished with a suitable appearance. The opposed flanges  18  are symmetrical about a central plane between the members of the web  17 . The flanges  18  have a horizontal portion  21  proximal to the web  17  and a vertical upstanding portion  22  distal from the web. The width of the tee  13 ,  14  and  15  measured horizontally from outside surface to outside surface is relatively narrow as compared to a standard flange width of say {fraction (15/16)} of an inch. For instance, in the preferred embodiment, the flange width can be nominally one-half inch. The web  17  is provided with holes for suspending it by suitable wires as is customary. The ends of the runners or tees  13 ,  14  have suitable connectors (not shown) for coupling to similar tees end-to-end or to receiving holes in transverse tees as is conventional. 
     A clip  26 , preferably stamped from suitable steel stock, is illustrated in detail in FIGS. 3 through 6. The clip  26 , when viewed from an end as in FIG. 6, is generally C-shaped or channel shaped. A bottom flange  27  of the clip or bracket  26  includes a pair of barbs  28  adjacent its ends and one at its center, each pointed away from a stepped web  29 . The web  29  is stepped with an offset  47  that conforms generally to the edge profile of the panels  12 . A top flange  31  of the clip  26  has a pair of grips  32  adjacent its ends that are turned downwardly. The web  29  has a generally vertically depending tab member  33  at its mid-length. The tab or hook  33  is stamped out of the plane of the adjacent web material so that there is a limited horizontal distance determined by a bight  43  between the plane of an upper part  34  of the web  29  and the plane of the tab  33 . 
     Identical clips  26  are attached to edges of a panel  12  as shown in FIGS. 7-9. In the illustrated arrangement, as suggested in FIG. 1, where the clips are shown in phantom, there are two clips provided on each of a pair of opposite edges of a panel  12 . The clips  26 , preferably installed on panel  12  at the factory where the panel is made, are located adjacent the upper face or back of the panel. The edges  36  of the panel receiving the clips or brackets  26 , are rabbeted with a shape that is complimentary to the cross-section of the clips. The panel  12  is ordinarily formed of a material soft enough to enable the barbs  28  and grips  32  to locally penetrate the body of the panel but strong enough such that the clips  26  are self-retained on the panel normally in a permanent manner. The rabbeted edges  36  include a portion  37  that extends horizontally beyond the bracket or clip  26 . Panel edges  38  at 90° from the edges  36  carrying the clips  26  are rabbeted with a relatively plain cross-section (FIG. 8) to leave a projecting lower portion  39 . 
     FIGS. 7 and 8 show the installed condition of the ceiling system  10  in cross-section. The vertical flange portions  22  of the grid runners  13 ,  15  are received in the bracket space or gap between the web  29  and the tab or hook  33 . The weight of a panel  12  is supported by an upper edge  41  of the vertical flange portion  22  received in this space and bearing against the bight  43  between the tab and adjacent part of the clip or bracket  26 . The width of this gap is precisely controlled such that there is very limited or no clearance with the vertical flange portion  22  so that the panel  12  is located accurately in horizontal position relative to the grid runners supporting the panel. 
     Vertical surfaces  44  of the rabbeted edges  38  of the panel  12  are located so that the panels are closely constrained by the outside surface, designated  46 , of adjacent grid runners. 
     It will be understood from the foregoing that the panels  12 , when installed, are very accurately located by the vertical flange portions  22  of the grid runners either through the clips  26  or through abutting contact with the surfaces  46 . This precise positioning enables the panels to be dimensioned to provide a relatively narrow gap, for example, ⅛″, between adjacent panels without the risk of visually noticeable variations in this gap which would otherwise detract from the appearance of the system  10 . It will be understood that the panels  12 , optionally, can be mounted with the clips  26  on the cross runners  14  such that the panels are rotated 90° about a vertical axis from that illustrated. 
     FIG. 9 illustrates a panel  12  being removed with downward access. To remove the panel  12 , it must be lifted at both edges  36  and then horizontally shifted. This lifting movement releases the hooks or tabs  33  on opposite edges  36  of the panel  12  from engagement with the vertical flange portions  22  on the supporting grid members  13  or  15 . While lifted, the panel  12  is shifted horizontally so that the hooks  33  on one side of the panel can drop below the associated vertical flange portion  22 . To allow limited horizontal shifting, the cross-sectional profiles of the clip  26  and the panel  12  provides respective recesses or offsets  47 ,  48  into which the adjacent flange  18  can be received. Once one edge  36  of the panel  12  is lowered below the plane of the adjacent panel it can be shifted in the opposite generally horizontal direction to allow the opposite panel edge to be lowered. The manipulation required to remove a panel  12  is intuitive because of the guiding functions of the vertical flange portions  22 . Initially, the panel  12  can only be raised and then be shifted horizontally in either of two opposite directions. A study of FIGS. 7 and 8 reveals that the panels  12  are supported by the grid in a stable manner such that they will not readily fall or otherwise become dislodged if they are accidentally bumped, particularly where only one edge is primarily raised and the panel is only tilted. 
     As another variant, the panels  12  can be modified at opposite rabbeted edges so that there is essentially no gap between adjacent edges  38  (FIG. 8) that do not carry the associated clips  26 . This variant will produce a more linear appearance in the ceiling where only the gaps between the panel edges associated with the clips will be apparent. 
     FIGS. 10 and 11 illustrate another form of the invention in which a ceiling system  50  includes conventional main runners or tees  51  and modified cross runners or tees  52 ,  53 . The main runners  51  have the ordinary shape of an inverted tee with horizontal flat flanges  54 , a vertical web  55  and a stiffening bulb  56 . The modified cross runners  52 ,  53 , in this embodiment, are either 4 foot or 2 foot in nominal length. The cross section of the cross runners  52 ,  53  is like that described above in connection with the embodiment of FIGS. 1 through 9 and corresponding elements are identified with the same reference numerals in the drawings. In this version, panels  60  have each of their four edges rabbeted with a profile that, in the illustrated case, is the same for each of the four edges. This profile includes a slot  61  with a downward facing horizontal surface  62  and an upward facing sloping surface  63 . A lower portion  64  of the panel edge is cantilevered out beyond an upper portion  65  of this edge. Vertical faces  66 ,  67  of the panel edge lie in different vertical planes with the lower face  66  being horizontally outward beyond the face  67  of the upper portion  65 . 
     A metal clip  69 , preferably assembled in pairs on a single panel edge, is similar to the clip  26  disclosed in connection with the embodiment of FIGS. 1 through 9. The clip  69 , typically formed as a sheet metal stamping, is generally channel-shaped with upper and lower flanges  71 ,  72 . The clip or bracket  69  is dimensioned so that the flanges  71 ,  72  tightly grip the upper edge area  65  to permanently retain the clip in precise location on the panel. The clip  69  is preferably installed at the factory where the panel  60  is made. Like the earlier described clip  26 , an integral depending hook or tab  73  is formed out of a web  74  of the channel-shaped clip  69 . When a panel  60  is installed on the grid, the hook  73  of each of the clips  69  is disposed over the vertical flange portion  22  of an adjacent runner  53 . The hook  73  is proportioned to overlie the vertical flange portion  22  of the adjacent runner with a minimum, if any, horizontal clearance. At the panel edge opposite the edge on which the clips  69  are mounted, the panel  60  is supported by contact between the horizontal slot surface  62  and an upper face  75  of the adjacent flange of a main tee or runner  51 . In the installed position of the panel  60 , edges  68  at 90° to the supporting edges associated with the clips  69  or the main tee flange face  75  are unrestricted in the vertical direction but are each horizontally confined by vertical flange portions  22  of adjacent runners  52 . 
     FIG. 12 illustrates the panel  60  being removed with downward access. For removal, the panel  60  is first lifted to release the hook or hooks  73  from engagement with the vertical flange portion  22  and then shifted slightly horizontally away from that flange portion. This horizontal movement is accommodated by the horizontal depth of the slot or groove  61 . The panel edge with the clips or brackets  69  is then lowered to the position illustrated in FIG.  12 . From this position, the panel can be shifted horizontally in the opposite direction to release the opposite edge  68  from engagement with the tee flange  54  and complete removal of the panel  60 . 
     FIGS. 13 and 14 illustrate another embodiment of the invention that again provides downward access. This embodiment is similar to that described in FIGS. 10 through 12. FIG. 13 is taken in a plane transverse to the longitudinal direction of main tees  80  and  2  foot cross tees  82 . FIG. 14 is taken in a plane parallel to the main tees and transversely through  4  foot cross tees  81 . The illustrated main tees  80  are of conventional construction while the cross tees  81  and  82  are characterized by a W-shaped flange construction similar to that disclosed in the other embodiments and particularly at FIG.  2 . “W” flanges  84  are relatively narrow in the horizontal direction and include vertical portions  85 . More specifically, the width of the W flanges  84  is somewhat narrower than that disclosed in FIG.  2 . Panels  87  are similar to the earlier described panels  12  and.  60 . Edges  88  of the panels  87  have slots  89  forming horizontal downwardly facing surfaces  91  and sloping upwardly facing surfaces  92 . All of the edges  88  of the panels  87  are identical. The panel  87  is supported on the grid in a manner similar to the arrangement disclosed in FIGS. 10-12. A lower portion  93  of the edge is cantilevered horizontally outward beyond an upper portion  94 . 
     One or more channel shaped clips  96  is permanently attached to one edge  88  of the panel  87  at the factory. The channel  96  grips the upper part  94  of the panel edge between its horizontal flanges  97 ,  98 . The clip  96  has a depending hook  99  stamped out of the plane of its web  101 . The panel edges  88 , at 90° to the edges on which the clip  96  is mounted, are reinforced by channel members  106 . The reinforcing or stiffening channels  106  are made of steel or other suitable material and embrace the upper edge portion  93  of the respective edges  88 . The channels  106  which run along the majority of the length of the related edges  88  resist the tendency of the panel  87  to sag over time along these edges. As shown in FIG. 13, the panel  87  is suspended by the clip  96  at one edge  88  and the slot surface  91  resting on the flange of a main tee  80  at the opposite edge. The hook  99  of the clip  96 , like the preceding embodiments, holds the vertical flange portion of the W flange  84  against the clip web  101  to accurately position the panel relative to the grid. The panels  87  in the embodiment of FIGS. 13 and 14 are removable in essentially the same manner as that described with the earlier embodiments. 
     Referring now to FIGS. 15-17 there is shown another embodiment of the invention of a suspended ceiling construction which provides “upward access” into the space above the ceiling. With this arrangement a panel  110  is lifted upward from its installed position to gain entry above the ceiling. The ceiling system comprises, in addition to the panels  110 , main tees or runners  111  and cross tees  112 ,  113 . The main tees  111  can be conventional in construction. The cross tees or runners  112 ,  113  have relatively narrow W-shaped flanges  114  like that generally shown in the embodiment of FIGS. 13 and 14 and similar to the other embodiments. 
     The four edges, designated  116  of each panel  110  preferably have identical profiles. An edge  116  includes a horizontal slot  117  that intercepts a generally vertical recessed face  118  of a rabbet in a lower portion of the edge  116 . An upper portion of the edge  116  having a generally vertical face  119  is cantilevered outwardly of the vertical surface  118 . The horizontal depth of the rabbet at the edge  116  is proportioned to receive the adjacent half of the W flange  114  of a cross runner with a limited clearance. 
     One or more channel-shaped clips  121 , preferably stamped from sheet steel, shown in FIG. 17, are fixed on one edge  116  of a panel  110 . The clip  121  includes a depending hook  122  integrally stamped out of a stepped web  123 . Flanges  124 ,  125  of the clip  121  are arranged to tightly grip an upper face of the panel and an upper surface of the associated slot  117 , respectively. 
     The panel  110  is suspended on the grid runners with the hook  122  engaged with the vertical portion of the adjacent area of a W flange  114  of a cross runner to support part of the weight of a panel. The panel  110  is also supported, at the opposite edge, by the upper surface of a slot  117  bearing on the top face  126  of a flange of a main runner  111 . The inter engagement of the hook  122  with the adjacent W flange portion prevents a panel  110  from shifting horizontally so that it is precisely located and resistant to being bumped out of place. The panel  110  can be removed by simply lifting it from its installed position. 
     FIGS. 18 and 19 illustrate still another form of the invention in which a ceiling system  130  includes main runners or tees  131  and cross runners or tees  52 ,  133 . The system  130  is similar to that disclosed in FIGS. 10 and 11 as well as FIGS. 1 through 9 and corresponding elements are identified with the same reference numerals. The main runners  131  have the shape of an inverted asymmetrical tee with a horizontal flat flange  54 , an angular flange  134 , a vertical web  55 , and a stiffening bulb  56 . The flange  134  includes a vertical portion  136 . The cross runners  133  have an asymmetrical profile like the main runners  131  which includes a flat flange  137  and an angular flange  138  with a vertical portion  139 . The cross runners  52 ,  133 , in this embodiment, are 4 foot and 2 foot in nominal length, respectively. 
     The panels  60  and clips  69  are like that of the embodiment of FIGS. 10 and 11. The hook  73  is proportioned to overlie the vertical flange portion  136 ,  139  of the adjacent runner  131 ,  133  with a minimum, if any, horizontal clearance. At the panel edge opposite the edge on which the clips  69  are mounted, the panel  60  is supported by contact between the horizontal slot surface  62  and the upper face of the adjacent flange  54  of a main tee or runner  131 , or an upper face of the flange  137  of a cross runner  133 . FIG. 20 illustrates the panel  60  being removed with downward access in the manner described above in connection with FIG.  12 . 
     While the invention has been shown and described with respect to particular embodiments thereof, this is for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein shown and described will be apparent to those skilled in the art all within the intended spirit and scope of the invention. Accordingly, the patent is not to be limited in scope and effect to the specific embodiments herein shown and described nor in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.

Summary:
A suspended ceiling system in which the grid runners are largely concealed by the panels to produce a distinctive high quality appearance. In various illustrated embodiments, the visual effect is produced as a result of the panels being separated by a relatively narrow gap in two perpendicular directions or by a narrow gap in one direction and essentially no gap in the perpendicular direction, and the grid being recessed above the main face of the panels. The panels are accurately positioned on the grid by metal clips, normally permanently attached to the panels, which engage upstanding flange portions of the grid runners. The accurate positioning afforded by the clips assures that visually distracting variations in the size of the narrow gaps are avoided. The clips can also serve to avoid accidental dislodging of the panels.