You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Suspended ceilings are used extensively in commercial and industrial buildings. In such ceilings, a metal grid framework of interconnected main beams and cross beams is hung from a structural element by wires. The grid supports acoustical panels in rectangular openings formed in the grid. 
     2. Prior Art 
     Suspended ceilings having metal beams interconnected into a grid that supports panels are well known. U.S. Pat. Nos. 5,839,246 and 6,178,712, for instance, incorporated herein by reference, show such ceilings. 
     Such prior art suspended ceilings generally have a grid of inverted T-beams, rolled from sheet metal, arrayed in rectangular fashion that is suspended from a structural ceiling by wires. The grid is created from main beams that extend longitudinally parallel to each other, and opposing cross beams connected at right angles to a main beam, to form repetitive rectangles that receive and support panels. The repetitive rectangles are generally formed in even rows, and extend side-by-side. The connections are formed by creating slots in the main beams that receive identical connectors on the end of the cross beams. In a connection, the connectors on each of a first and second opposing cross beams are connected through a slot in the main beam to each other, and to the main beam, so that a secure and strong connection results between the opposing cross beams, and the main beam. If only a first connector is inserted into the slot, without being connected to an opposing identical second connector, the connection will not hold. The first connector is only loosely held in the slot until the second connector on the second opposing beam is forced into the slot along the first connector. 
     The present invention relates to such connection. 
     SUMMARY OF THE PRESENT INVENTION 
     The adapter of the present invention enables a strong connection between a single cross beam and a main beam, through a slot in the main beam, in a ceiling grid, using some of the same prior art connector elements used to make a two cross beam connection through a slot, as described above. Such a connection is, in some instances, desired for a decorative effect, wherein an area, or areas, of the ceiling are clear of a cross beam that extends in line with an opposing cross beam. This results in a type of running brick bond design, such as used in a brick wall. In other instances, the omission of a second opposing cross beam is necessary to create an open area to accommodate a ceiling fixture, such as a fluorescent light fixture, or a ventilator. 
     It is necessary under building codes that all cross beams be retained in their connections under stress, for instance, of a 180 pound pull, particularly during seismic events, so the ceiling does not collapse. The connection of the invention between a single cross beam and, using the adapter disclosed, a main beam, complies with such a requirement, based on laboratory tests. 
     The present invention comprises an L-shaped adapter. A first leg of the adapter is inserted from the side opposite the first cross beam, through the slot in the main beam, alongside a first connector on the opposing first cross beam, that has already been inserted into the slot. The adapter provides a means to keep the connector on the first cross beam engaged with the main beam, since the adapter occupies the space in the slot that in the prior art is occupied by the omitted second connector on the end of the omitted second beam. 
     The first leg of the L-shaped adapter extends to and along the web of the first cross beam already in the slot, and is secured to the cross beam by, for instance, a rivet. 
     The second leg of the L-shaped adapter extends along the web of the main beam, on the side of the main beam opposite the first cross beam. 
     This arrangement prevents a pull out of the first cross beam from the slot in the main beam, under stress, such as in a seismic event. 
     The present connection, notwithstanding there is an omitted second connector and second cross beam from the connection of the prior art, will retain its resistance to separation of the first cross beam and first connector, in compliance with governing codes, from the main beam, based on laboratory tests. 
     In summary, with the present invention, a conventional prior art suspended ceiling designed to have opposing first and second cross beams connect with each other, and with a main beam, can be readily adapted to a connection having only a single first beam connected through a slot in the main beam. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view taken from above, of a prior art suspended ceiling. 
         FIG. 2  is an enlarged perspective view taken from above of a connection between a main beam and opposing cross beams, in the ceiling shown in  FIG. 1 , with a portion of the connection broken away. 
         FIG. 3  is a view looking downward of a suspended ceiling that is using the adapter of the invention to connect a first cross beam only to a main beam, to create a running bond effect. 
         FIG. 4  is a perspective view of the adapter of the invention. 
         FIG. 5  is a perspective view of a connection between a main beam, and a single first cross beam, using the adapter of the invention. 
         FIG. 6  is a side elevational view of the connection of  FIG. 5 . 
         FIG. 7  is a sectional view of the connection of the invention taken on the line  7 - 7  in  FIG. 6 . 
         FIG. 8  is a perspective view of the connection of the invention with a first cross beam inserted into the slot of a main beam, and the adapter about to be inserted into the slot, from the side opposite the first cross beam. 
         FIG. 9  is a perspective view of the connection of the invention, showing a portion of the connector on the first cross beam extending beyond the web of the main beam, on the side opposite the first cross beam, with the adapter of the invention in place. 
         FIG. 10  is the perspective view of  FIG. 9 , with the portion of the connector extending beyond the web of the main beam cut away. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Prior Art 
     There is shown in  FIG. 1  a prior art suspended ceiling  20  having parallel spaced main beams  21  and first and second identical opposing cross beams  22  and  23 . First cross beam  22  has affixed at its end connector  26 , and second cross beam  23  has affixed at its end identical connector  27 . The connectors  26  and  27  extend through a slot  28  in the main beam  21 , from opposing sides of the main beam  21 , and lock with each other (sometimes styled a “handshake” in the prior art) and with the main beam  21 , to form a connection  30 . 
     As well known in the art, such a connection  30  must have opposing connectors, (such as  26  and  27 ) extending in the slot  28  beside each other in close contact with each other. A single connector in the slot, such as connector  26 , simply pulls out since a single connector in the slot is a loose fit. A first cross beam connector  26  in the slot, is designed to lock with the opposing connector  27  in the slot in a confined space. The opposing first and second connectors  26  and  27  fully occupy the slot. A flexible tab  31  flexes when a second connector  27  goes through a slot, and then expands to lock to the slot  28 . 
     As seen in  FIGS. 1 and 2 , a typical connector  26  has a body portion  32  and the tab  33  that engages the side of the slot  28  to prevent withdrawal when opposing connectors  26  and  27  are in the slot. A barb  35  on each of the first and second connectors  26  and  27  that engage one another when the second opposing connector  27  on second opposing cross beam  23  is inserted into the slot  28 . Such an arrangement is shown in detail in U.S. Pat. Nos. &#39;246 and &#39;712 as referred to above. 
     The present invention is concerned with adapting a prior art connection  30  as described above, with a first  22  and second  23  opposing cross beam, into a connection  40  between a single first cross beam  22 , and a main beam  21 , that results in a grid  41  as depicted in  FIG. 3 . One or more of connection  40  can be used in such grid  41 . 
     In the connection of the invention  40 , the second cross beam  23  and second connector  27  are omitted, and the adapter  42  of the invention inserted. 
     The adapter  42 , as seen in  FIG. 4 , has an angle shape, with one leg  43  of the adapter  42  intended to lie along the main beam web  45 , through the slot  28  of the main beam  21 , alongside the connector  26  on the first opposing cross beam  22 . Adapter  42  replaces the connector  27  on a second opposing cross beam  23 , which is being omitted. First leg  43  of the adapter  42  of the invention keeps the prior art first connector  26  in place against the edge of the slot  28  of the main beam  21 , to prevent withdrawal, as did the omitted second connector  27  in the prior art. 
     The second leg  46  of the adapter  42 , as seen in  FIG. 5 , lies along the web  45  of the main beam  21 . The leg  46  has a larger portion  47  intended to extend above and across the slot  28 . 
     Second leg  46 , of adapter  42 , extends along web  45  of the main beam  21 , on the side of connector  26  that permits the connector to extend beyond the web  45 , as seen at  48 , in  FIG. 9 . 
     In such a position, first leg  43  of adapter  42  extends through slot  28  in main beam  21  into a position as seen, for instance, in  FIG. 6 . 
     As seen in  FIG. 6 , first leg  43  extends along first connector  26 , in place of the prior art second connector  27  shown in  FIG. 2 . 
     A rivet  50 , or other fastener, as seen particularly in  FIGS. 6 and 7 , passes through connector  26 , through web  53  and through elongated hole  51  on first leg  43 . 
     First leg  43  of adapter  42  is slightly offset at  52  to permit the web  53  of first cross beam  22  to be sandwiched between leg  43  of adapter  42  and connector  26 , as seen best in  FIG. 7 . 
     In the arrangement as shown in  FIG. 9 , the connection of the invention is complete, except for the end  55  of connector  26  which extends beyond web  45  on main beam  21 . End  55  of connector  26  is manually cut off as seen in  FIG. 10 , so that there is no interference with a panel  58  that extends across the connection, as seen in  FIG. 3 . 
     In the connection of the invention  40  as described, using the adapter  42  of the invention, the first connector  26  on the first opposing cross beam  22 , is prevented from withdrawing from slot  28  of main beam  21  by (1) the connection of first connector  26  to the side of the slot  28 , and by (2) the adapter  42  which secures the first leg  43  of the adapter  42  to the first connector  26 , with the second leg  46  of the adapter extending along, and against the web  45  of the main beam  21  on the side of the main beam  21  opposite the first cross beam  22 , so the first connector  26  cannot pull out of slot  28 . 
     Hole  51  is slotted to compensate for any variance in the position of the first cross beam  22  and connector  26  with respect to the main beam  21 . 
     Slot  57  in leg  43  of adapter  42  permits an easier installation of the clip in its position alongside clip  26 , as seen, for instance, in  FIG. 7 .

Summary:
An L-shaped adapter that secures a single cross beam to a main beam, in a suspended ceiling. 
     The adapter is applied to a prior art connection designed to connect opposing cross beams to each other and to a main beam.