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FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to suspended ceilings and more specifically relates to wall brackets and clips used to construct a ceiling for handling seismic events 
       BACKGROUND 
       [0002]    Suspended ceiling grids are widely used in commercial and even some residential buildings as they allow ready access to services such as air conditioning, wiring and plumbing that are located in the ceiling space. They are particularly advantageous in multi-story buildings as they allow access whilst minimizing ceiling depth. 
         [0003]    If seismic movement was not an issue a ceiling grid could be constructed using only fixed wall angles with main tees and cross runners being fixedly attached by simple means such as fixed angle brackets, to either side of the grid extent in any building area. 
         [0004]    To allow for some movement of opposing walls a grid can be made with the tees and cross runners attached at one end only with the free end resting upon a wall angle. In high earthquake areas a 50×50 mm wall angle is typically used to facilitate necessary grid movement. These wall angles are unsightly and traditionally unacceptable architecturally. The free end of the runners resting upon the angle produces an uneven ceiling surface that provides a harbour for dirt and bacteria. Such an arrangement is clearly unsuitable for use in clean rooms or medical facilities where a high degree of cleanliness and hygiene is required. 
         [0005]    To maintain structural integrity during seismic events suspended ceilings incorporate 5 way bracing support at very regular intervals i.e. 4 m×4 m or 3.6×3.6 m. The braces attach the joins between cross members to the ceiling proper and in doing so significantly congest the ceiling cavity. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an object of the invention to provide a wall bracket that allows for seismic movement whilst providing an even ceiling surface and to provide a clip for joining tee members of a suspended ceiling system with high strength whilst minimizing intrusion of ceiling space. 
         [0007]    In a first aspect the invention provides a wall bracket system for movably securing a suspended ceiling, comprising a fixed member for attaching to a wall including a horizontal flange and ramp portion and a floating member including a horizontal flange and ramp portion, wherein the floating member ramp portion sits atop the fixed member ramp portion and the floating member is fixedly attached to a slide which is slidably attached to a tee member of the suspended ceiling. 
         [0008]    Preferably the floating member is movable between a first floating position in which the floating member horizontal flange is coplanar with the fixed member horizontal flange and a second floating position in which the floating member horizontal flange sits atop the fixed member ramp section. 
         [0009]    Preferably the slide allows the tee member to slidably move between a first tee position adjacent to the movable member to a second tee position spaced apart from the movable member. Preferably the tee member comprises a flange which forms a contiguous flat surface with the floating member horizontal flange when the tee member is in the first tee position. 
         [0010]    Preferably the slide is attached to the tee member by an elastically deformable member which biases the floating member towards the tee member. 
         [0011]    Preferably the floating member includes a hook which engages a hook of the fixed member to prevent movement of the floating member from the first floating position when the tee member move from the first tee position to the second tee position. 
         [0012]    In a second aspect the invention provides clip for joining tee members of a suspended ceiling, comprising first and second elongate arms, wherein a first end of the first arm is attached to the first end of the second arm and the second end of the first and second arms includes means for attaching to the tee members. 
         [0013]    Preferably the attachment means comprises a hook. 
         [0014]    Preferably the clip is made from an elastically deformable material. 
         [0015]    It should be noted that any one of the aspects mentioned above may include any of the features of any of the other aspects mentioned above and may include any of the features of any of the embodiments described below as appropriate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows. 
           [0017]    Reference will now be made, by way of example only, to the accompanying drawings. 
           [0018]      FIG. 1A  shows a suspended ceiling grid incorporating a wall bracket and clip according to a preferred embodiment of the present invention. 
           [0019]      FIG. 1B  shows a close up portion of the grid of  FIG. 1A  detailing the wall bracket and its attachment to a tee member of the grid and a clip holding tee members together 
           [0020]      FIGS. 2A and 2B  show the engagement of the fixed and floating portions of the wall bracket in perspective and side views. 
           [0021]      FIGS. 2C and 2D  show the fixed floating portions of the wall bracket in perspective and side views. 
           [0022]      FIGS. 2E and 2F  show the fixed portion of the wall bracket in perspective and side views. 
           [0023]      FIG. 3  shows details of a cross runner. 
           [0024]      FIG. 4  shows a floating clip base. 
           [0025]      FIG. 5  shows a floating clip base attached to a cross runner 
           [0026]      FIG. 6  shows a floating clip slide. 
           [0027]      FIG. 7  shows a floating clip slide engaging a sliding clip base. 
           [0028]      FIGS. 8A to 8C  shows a floating clip slide engaging with the wall bracket. 
           [0029]      FIG. 9  details a wall bracket and clip in a neutral position. 
           [0030]      FIG. 10  details a wall bracket and clip during a seismic event wherein the walls are moving apart. 
           [0031]      FIG. 11  details a wall bracket and clip during a seismic event wherein the walls are moving together. 
           [0032]      FIG. 12A  shows a first perspective view of a clip for joining tee members. 
           [0033]      FIG. 12B  shows a second perspective view of the clip. 
           [0034]      FIG. 13A  shows tee members and a clip coming together to be joined. 
           [0035]      FIG. 13B  shows details of tee members joined by a clip. 
       
    
    
     DRAWING LABELS 
       [0036]    The drawings include items labeled as follows:
     10  Suspended ceiling grid     20  Fixed wall angle     22  Fixed angle bracket     30  Main Tee     33  Main Tee strengthening bulb     36  Main Tee attachment hole     40  Cross runner (Cross Tee)     41  Cross runner web     42  Cross runner horizontal flange     43  Cross runner strengthening bulb     44  Cross runner attachment finger     45  Cross runner attachment spring     46  Cross runner clip hole     47  Cross Tees mounting holes     50  Floating wall angle     60  Floating angle wall member     61  Wall member vertical flange     62  Wall member horizontal flange     63  Wall member ramp     64  Wall member hook     65  Wall member locating groove     70  Floating angle floating member     71  Floating member vertical flange     72  Floating member horizontal flange     73  Floating member ramp     74  Floating member hook     75  Floating member locating ridge     76  Floating member clip cavity     80  Floating clip     82  Floating clip base     83  Floating clip base attachment holes     84  Floating clip base retaining tee     85  Rivets     90  Floating clip slide     91  Floating clip slide mounting slot     92  Floating clip slide sliding slot     93  Floating clip slide band anchor     94  Floating clip slide attachment tee     95  Floating clip elastic band     100  Tee clip     101  Tee clip arms     102  Tee clip hooks     200  Movement apart     201  Gap     300  Movement together   
 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0082]    The following detailed description of a preferred embodiment of the invention refers to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. As used herein, any usage of terms that suggest an absolute orientation (e.g. “top”, “bottom”, “front”, “back”, “horizontal”, etc.) are for illustrative convenience and refer to the orientation shown in a particular figure. However, such terms are not to be construed in a limiting sense as it is contemplated that various components may in practice be utilized in orientations that are the same as, or different than those, described or shown. Dimensions of certain parts shown in the drawings may have been modified and/or exaggerated for the purposes of clarity or illustration. In particular the present invention relates to a ceiling system which inherently includes long elements with relatively small features. Such elements have been shown shortened to aid clarity. 
         [0083]    The present invention provides a wall bracket system that can withstand seismic events and presents a contiguous flat ceiling surface wherein no component rests on top of another component and provides a clip for joining tee members of a suspended ceiling system together with high strength whilst minimizing intrusion into the ceiling space above. 
         [0084]      FIG. 1A  shows a suspended ceiling grid  10  incorporating the present invention, comprising an outer frame made of wall angles  20  and  50 , main tees  30  spanning opposing wall angles and cross runners (cross tees)  40  spanning adjacent main tees and/or wall angles. Such an arrangement is similar to prior art grids and provides a regular grid for supporting ceiling tiles. In a first aspect the present invention differs from the prior art in the particulars of the wall angles  50 , the clips  80  used to attach the wall angles to the tees and runners. In a second aspect the present invention differs from the prior art in the clips  100  used to secure the runners  40  to the main tees  30 . 
         [0085]    First of all it will be explained how the ceiling grid is attached to allow movement whilst still presenting a contiguous surface. The main tees  30  and cross runners  40  are fixedly secured at a first end to the wall angles  20  by means of wall angle brackets  22 , and movably secured at a second end to floating wall angles  50  by means of floating clip  80 . This arrangement allows the walls to which the angles  20  and  50  are attached to move with respect to each other during a seismic event whilst still maintaining the structural integrity of the ceiling grid. The integrity of the grid is further maintained by clips  100  which secure the cross runners  40  to the main tees  30 . 
         [0086]      FIG. 1B  shows a close up portion of the grid  10  in which can be seen that the floating wall angle  50  comprises a fixed member  60  and a floating member  70 , and the clip  80  comprises a base portion  82  and sliding portion  90 . 
         [0087]    The floating wall angle  50  is shown in detail in  FIGS. 2A to 2F  with  FIGS. 2A and 2B  showing the fixed member  60  and floating member  70  fitted together in perspective and side views;  FIGS. 2C and 2D  show the fixed member  60  and  FIGS. 2E and 2F  show the floating member  70 . 
         [0088]    The fixed member  60  comprises vertical flange  61 , horizontal flange  62 , ramp  63  and hook  64 . The ramp  63  is at an acute angle to the flange  62  thereby allowing a floating member  70  to slide over the fixed member and towards the vertical flange  61 , whilst hook  65  restrains the floating member from moving away from the vertical flange. 
         [0089]    The floating member  70  comprises vertical flange  71 , horizontal flange  72 , ramp  73 , hook  74  and cavity  76 . The ramp  73  is at an obtuse angle to the flange  71  to allow the ramp  73  to slide over the ramp  63  of the fixed member  60 . The ramp  73  and hook  74  complement the ramp  63  and hook  64  of the fixed member, allowing movement in a first direction, but restricting it in a second. The cavity  76  provides a means of engaging the slide  90  of the clip  80 . 
         [0090]    The fixed member  60  and floating member  70  nominally fit together in a neutral position as shown in  FIG. 2A and 2B  wherein the respective horizontal flanges  62  and  72  align to form a contiguous flat surface. Alignment groove  65  of the fixed member and alignment ridge  75  of the floating member aid in aligning the two members in such a neutral position. 
         [0091]      FIGS. 3 to 7  show details of a floating clip  90  and how it is attached to the end of a cross runner  40 . The clip  90  may be attached to the end of a main tee  30  in a similar manner. 
         [0092]    As seen in  FIG. 3  a cross runner  40  comprises a vertical web  41  with a strengthening bulb  43  atop, opposed horizontal flanges  42  (of which only one can be seen in  FIG. 3 ) and attachment finger  44  with attachment spring  45  for securing the cross runner to a main tee. The clip hole  46  is used for engaging a clip to secure adjacent cross runners together and to a main tee. The cross runner shown has only one attachment finger at a first end as the second end is to have a floating clip attached via mounting holes  47 . Where a cross runner is to be located between two main tees it would instead have a further attachment finger  44 , spring  45  and clip hole  46 . 
         [0093]      FIG. 4  shows a floating clip base  82  which provides retaining tees  84  for slidably attaching and retaining a floating clip slide  90 . The base includes attachment holes  83  to facilitate attaching the clip to a cross runner by riveting. The base is shown attached to a cross runner in  FIG. 5 . 
         [0094]      FIG. 6  shows a floating clip slide  90  comprising a body with mounting slots  91 , sliding slots  92 , rubber band anchor  93  and attachment tee  94  for attaching the slide to a wall angle. To fit the slide  90  to a base  82  the retaining tees  84  of the base are passed through the mounting slots  91 . The slide is then able to slide back and forth on the base to the extent of the sliding slot  92 . As shown in  FIG. 7 , a rubber band  95  is fitted between the attachment tee  94  of the slide and retaining tee  84  of the base and acts to keep the slide in a neutral position as also seen in  FIG. 9 . 
         [0095]    The clip may take the form of several different embodiments. In one further embodiment the clip base is integrally formed with the cross runner or main tee. In another embodiment the rubber band is replaced with a spring. In other embodiments the retaining tee is replaced with a stud. Other embodiments are readily envisaged, all however must provide a means for fixedly attaching the clip to a wall angle and slidably attaching to a main tee or cross runner and further provide a spring means to return the clip and any attached wall angle to a neutral position following movement. 
         [0096]    A clip slide  90  can be attached to a floating wall angle as show in  FIGS. 8A to 8C . The slide may be attached either before or after fitting to a slide base. The slide is first rotated such that its attachment tee  94  may enter the floating member clip cavity  76  and then rotated so that the attachment tee engages the cavity thus firmly attaching the two elements. 
         [0097]    Movement of the components during a seismic event can be appreciated with the aid of  FIGS. 9 to 11 . Before a seismic event the components provide a contiguous ceiling surface. This surface is disturbed during the event, but is restored afterwards. 
         [0098]      FIG. 9  shows the components in a neutral position as would be the case when a ceiling grid is installed. The fixed member  60  and floating member  70  sit fit together in a neutral position in which they are maximally separated, and the slide  90  of the floating clip  80  is retracted by the elastic band  95 . The respective horizontal flanges  62  and  72  of the fixed and floating member align to form a contiguous flat surface together with the horizontal flange  34  of the main tee  30 . This contiguous surface is advantageous in being aesthetically pleasing as well as physically isolating a ceiling space from the room below. This is particularly desirable when in clean room situations such as hospitals. 
         [0099]    In  FIG. 10  the main tee  30  has been pulled away from the fixed member  60  as indicated by arrow  200  as would happen in a seismic event when the walls to which the main tee and fixed member move apart. The clip base  82  moves in tandem with the main tee away from the clip slide  90  which remains attached to the floating member  70 . The floating member remains fixed in its neutral position as its hook  74  is engaged with the hook  64  of the fixed member  60 . The elastic band  81  spanning the clip base  82  and slide  90  stretches and a gap  201  opens up between the main tee flange  34  and the floating member horizontal flange  72 . When the tee returns to original position as in  FIG. 9 , the elastic band will act to keep the floating member in the neutral position and the gap  201  will close. 
         [0100]    In  FIG. 11  the main tee  30  has been pushed towards the fixed member  60  as indicated by arrow  300  as would happen in a seismic event when the walls to which the main tee and fixed member move towards each other. The clip base  82  moves in tandem with the main tee and as the base retaining tee  84  is at the right hand extremity of the clip sliding slot  92  the clip slide  90  also moves towards the fixed member. As the floating member  70  is attached to the clip it also moves, with its ramp  73  riding up the ramp  63  of the fixed member. When the tee returns to original position as in  FIG. 9 , the elastic band will act to pull the floating member back to the neutral position. 
         [0101]    Whilst the above embodiment describes the attachment of the bracket to a wall it may equally well be attached to a post or other structure and is not intended to limit the invention to this particular embodiment. 
         [0102]    The reader will appreciate the first aspect of the present invention which provides a seismic ceiling system that can withstand seismic events and presents a contiguous flat ceiling surface wherein no component rests on top of another component. This feature is critical in hygiene critical environments such as hospitals. 
         [0103]    Now to focus on the second aspect of the invention, the clip that is used to hold the tee members together. Details of a clip  100  are shown in two different perspective views in  FIGS. 12A and 12B . The clip  100  comprises arms  101  disposed at approximately 120 degrees to each other and attachment means in the form of small hooks  102  at the end of each arm. The clip  100  is made of an elastically deformable material such as mild steel. 
         [0104]      FIGS. 13A and 13B  illustrate the joining of two cross runners  40  to a main tee  30 . As is the prior art the main tee includes an attachment hole  36  into which the attachment fingers  44  of the cross runners are placed. Once in the hole, attachment springs  45  return to their resting position and lock the cross runners in place. Such a joining mechanism provides limited strength and is only capable of withstanding low force seismic events. Prior art systems often supplement such joins with extensive 5 way bracing and hence occupy a large volume of ceiling space. In the present invention clip  100  is placed on top of the strengthening bulb  33  of the main tee  30  and held in place by the clip hooks  102  engaging the clip holes  46  of the cross runner. The resulting joint is strong enough to withstand severe seismic events. The location of the holes  46  and dimensions of the clip  100  are chosen such that the clip must be flexed slightly to be fitted. The clip  100  thus acts as a spring against the top of the main tee  30  and the sides of the holes  46  holding the various components tightly together. 
         [0105]    In further embodiments the clip attachment means can take other forms, for example a loop which can either be fixed to a cross runner by a screw or the like or simply placed over a protruding member of the cross runner such as a stud. 
         [0106]    The reader will appreciate the second aspect of the present invention which provides a clip for joining main tees and cross runner that produces joints capable of withstanding severe seismic events whilst minimizing intrusion of ceiling space. An increased strength of 30% or more in comparison to prior art systems has been demonstrated in practical testing. 
         [0107]    Together the brackets and the clip provide a ceiling system that is strong and flexible for handling seismic events whilst presenting a smooth ceiling and not intruding into the ceiling space. 
         [0108]    Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus. Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in this field. 
         [0109]    In the present specification and claims (if any), the word “comprising” and its derivatives including “comprises” and “comprise” include each of the stated integers but does not exclude the inclusion of one or more further integers.

Summary:
Components for a suspended ceiling subjected to seismic events including a fixed bracket and a movable bracket presenting a contiguous flat ceiling surface under normal conditions. The movable bracket is able to slide up onto the fixed bracket during a seismic event and is returned to a neutral position with the aid of a sliding clip elastically attached to a main tee or cross runner of the ceiling. A clip for joining tee members of a suspended ceiling is provided comprising two joined arms with hooks at the end of each arm. The join of the arms sits atop a main tee member and the hooks of each arm engage cross members thus securing the members together.