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FIELD OF THE INVENTION  
         [0001]    This invention relates generally to indoor ceilings and, more particularly, to suspended ceilings made of wood.  
         BACKGROUND OF THE INVENTION  
         [0002]    Suspended ceilings (sometimes referred to as drop ceilings) for indoor use are well known in the art. Suspended ceilings are usually used in areas where pre-existing utility equipment is found and cannot easily be relocated. For example, many buildings (commercial and residential) have duct work, electrical wires, gas and water pipes strung near the ceilings of each floor (or below each floor). In order to preserve access to this equipment (i.e., for maintenance) they are usually left exposed either completely or partially and are hidden by a suspended ceiling. In other areas, where floor space is at a premium, it may be desirable to finish the ceiling quickly and inexpensively by using a suspended ceiling.  
           [0003]    Typical suspended ceilings consist of aluminum dividers suspended from the existing ceiling by wires and pre-formed panels made from recycled products. A drawback of these typical drop ceilings is that there is very little diversity in the ceiling panels and the aluminum dividers. The aluminum dividers are typically white. The panels are usually also white in color and have an irregular (similar to the appearance of plaster) texture. Also, the panels are damaged easily and tend to turn yellow over time.  
           [0004]    Drop ceilings made of wood are also known. For example, Kern U.S. Pat. No. 4,464,876 discloses a suspended wood beam ceiling and related mounting hardware used to support the various wood beams. Kern discloses the use of translucent light panels or decorative opaque panels suspended between the wood beams to enhance the appearance and/or match the decor of the room.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention is a drop ceiling system made of wood. In one embodiment, the present invention has perimeter supports along the walls and a single center beam to support a plurality of ceiling panels. A cleat is attached on at least one side of each ceiling panel which communicate with a joint formed on the perimeter supports to secure the panels to the perimeter support and prevent the accidental displacement of the wood panels.  
           [0006]    The present invention allows the ceiling panels to be quickly replaced to change the appearance of the room or area. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and, together with the following description, serve to explain the principles of the invention. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred, it being understood, however, that the invention is not limited to the specific instrumentality or the precise arrangement of elements or process steps disclosed.  
         [0008]    In the drawings:  
         [0009]    [0009]FIG. 1 is an back isometric view of a suspended wood ceiling in accordance with the present invention, with parts broken away and parts taken in section, showing a ceiling panel in projected position;  
         [0010]    [0010]FIG. 2 is a front isometric view of a suspended wood ceiling in accordance with the present invention with parts taken in section, showing two ceiling panels in projected position—one each on either side of the center beam;  
         [0011]    [0011]FIG. 3 is and enlarged section view of a suspended wood ceiling in accordance with the present invention for a room that can be spanned with two rows of ceiling panels and one center beam;  
         [0012]    [0012]FIG. 4 is a back isometric view of a typical rectangularly-shaped ceiling panel;  
         [0013]    [0013]FIG. 5 is an enlarged end view of the ceiling panel illustrated in FIG. 4 taken along line  5 - 5 ;  
         [0014]    [0014]FIG. 6 is an isometric view of the center beam attached to an L-shaped bracket used to secure the center beam; and  
         [0015]    [0015]FIG. 7 is an enlarged section view of a side beam illustrating a rabbit joint.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    In describing a preferred embodiment of the invention, specific terminology will be selected for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.  
         [0017]    Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings in which a suspended wood ceiling in accordance with the present invention is generally indicated at  10 .  
         [0018]    Referring to FIG. 1, two interior walls  90 ,  92  of a room, shown in section, are illustrated. Although the present invention may be adapted for use in a variety of sized and shaped rooms, the present description will assume that the room is rectangularly-shaped having four walls that meet at substantially right angles. As shown in FIG. 3, third wall  94  is an antipode to wall  90 ; an antipode of wall  92  is not shown. Although not illustrated, all four walls of the room including walls  90 ,  92  and their respective antipodes extend upwards from a floor  91  to a ceiling.  
         [0019]    The ceiling (especially one in the basement of a house) is usually the underside of a floor on the immediate upper level. Directly below the floor are joists which support the floor. Electrical and telephone wires, plumbing, duct work and similar features are strung on, through and under the joists. The joists, wires, plumbing and duct work are exposed and visible to an observer in the basement.  
         [0020]    At least one weight-bearing side beam  12  (sometimes referred to as a perimeter support) is attached to the first wall  90  and a similar number of weight-bearing side beams  12  are attached to the opposite wall  94 . In a preferred embodiment, dry wall screws  29 , nails or similar means are used to secure perimeter supports  12 . A number of well-known devices (e.g., butterfly bolts for a concrete wall) may also be used depending on the material used to construct the wall. The choice of which type of attachment means to secure the perimeter supports  12  to the walls will depend on several factors including preferences of the installer, the type of walls in the room (e.g., drywall, plaster, concrete blocks, etc.), the size and weight of the wooden ceiling panels, and, to a lesser extent, the size of the room.  
         [0021]    A center beam  14 , non-weight-bearing side beams  19  and a plurality of ceiling panels  20  complete the major components of a suspended wood ceiling in accordance with the present invention. As will be more fully described hereafter, the weight of the plurality of ceiling panels is borne by the weight-bearing side beams  12  and the center beam  14 .  
         [0022]    Since it is assumed that the entire ceiling will be covered by the suspended wood ceiling  10 , the perimeter supports  12  are attached along the entire length of two diametrically opposed walls  90 ,  94  in the room as illustrated in FIG. 3. Unless some special effect is trying to be achieved, the perimeter supports  12  are leveled when they are attached to the walls  90 ,  94 . Each perimeter support  12  has a rabbit joint  13  which will be fully described later herein in connection with FIG. 7.  
         [0023]    If the room is small enough (or if a single perimeter support  12  is long enough) one perimeter support can span an entire wall. However, since it will be preferable to standardize the length of the perimeter supports  12 , two or more perimeter supports  12  (and possibly even a partial perimeter support) will usually be required to span one wall.  
         [0024]    In one embodiment, it may be desirable to standardize the length of the perimeter supports at five feet. For a wall that is eleven feet long, two perimeter supports  12  plus a third perimeter support cut to one foot in length would be needed.  
         [0025]    Referring now to FIG. 2, the non-weight-bearing side beams  19  are attached to the remaining diametrically opposed side walls of the room. The non-weight-bearing side beams  19  are for decorative purposes and are not needed to support the weight of the ceiling panels  20 . Non-weight-bearing side beams  19  have the same outer appearance as the perimeter supports or weight-bearing side beams  12 ; however, they do not require a rabbit joint  13 . The non-weight-bearing side beams  19  are used to give the same fit, appearance and finish to the ceiling as given by the weight-bearing side beams  12 . (It would be apparent to one skilled in the art, after a thorough reading of the present disclosure, that weight-bearing side beams  12  can be used on all four walls, just that on two walls the rabbit joint will not be used.)  
         [0026]    The non-weight bearing beams  19  are preferably leveled and placed even to the perimeter supports  12 . The distance the perimeter supports  12  and the non-weight bearing beams  19  are spaced down from the unfinished ceiling will depend on the location of the duct work, wires and plumbing, and the overall height of the room. If the room is sufficiently high, the perimeter supports  12  and the non-weight bearing beams  19  may be spaced upwards from the floor (for example, to achieve an eight-feet high “standard” ceiling).  
         [0027]    Referring again to FIGS. 1 and 2, the center beam  14  is suspended from the existing ceiling of the room. The means for attaching the center beam  14  will be described later herein. The center beam  14  is designed to extend from the second wall  92  to a wall (not shown) diametrically opposed to the second wall  92 . The center beam  14  runs substantially parallel to the first wall  90 , the third wall  94  and to perimeter supports  12 ; the center beam  14  would then be substantially perpendicular to the non-weight bearing beams  19 .  
         [0028]    Referring to FIG. 3 again, a cross-sectional view of the suspended ceiling system  10  in accordance with the present invention is illustrated. In a typical room, only one center beam  14  is required. For example, in a ten feet by twelve feet sized room (i.e., ten feet between first wall  90  and its antipode  94 , and twelve feet between second wall  92  and its respective antipode), only one center beam  14  and two columns A, B of ceiling panels  20  are required. In this example, the center beam  14  is truly in the center of the room (i.e., about five feet from wall  90  and five feet from wall  94 ) and it physically divides the room in half.  
         [0029]    Continuing to refer to FIG. 3, the center beam  14  is designed to support a portion of the weight of the plurality of ceiling panels  20  in column A and a portion of the weight of the plurality of ceiling panels  20  in column B. Weight-bearing side beam  12 A supports a portion of the weight of the plurality of ceiling panels in column A, while weight-bearing side beam  12 B supports a potion of the weight of the plurality of ceiling panels in column B. (It should be noted that side beam  12 A is substantially identical to side beam  12 B; the different reference numerals are used to distinguish the beam  12 A proximate column A from the beam  12 B proximate column B.)  
         [0030]    Center beam  14  is designed to bear a portion of the weight of the two columns of ceiling panels  20  located on either side of center beam  14 . Although it is called a “center” beam, there may be more than one “center” beam  14  if the room is large enough. They are referred to as “center” beams because in a typical room, only one beam  14  will be needed (i.e., in the center of the room) with two rows of ceiling panels  20 .  
         [0031]    For example, if the room is large, the installer of the present ceiling system  10  may decide to use one center beam  14  and two columns of ceiling panels to cover the entire ceiling. However, the installer may decide to use two “center” beams  14 , in which case, three columns of ceiling panels  20  will be required. Similarly, if the installer calls for three center beams, then four columns of ceiling panels will be required, and so on.  
         [0032]    In a preferred embodiment, the face of the center beam (i.e., the portion that will be seen from inside the room) will be stained, painted, carved and/or machined to match the fit and appearance of perimeter supports  12  and weight-bearing beams  19 .  
         [0033]    The center beam  14  may be flat on their back sides (i.e., the side facing the unfinished ceiling) in one embodiment. In another embodiment, each center beam  14  has two channels  16 ,  18  that run parallel to the longitudinal dimension (i.e., length) of the center beam  14 , and along the entire length of the center beam. The purpose of these channels  16 ,  18  will be discussed further hereinafter.  
         [0034]    Referring again to FIGS. 1 and 2, a ceiling panel  20  is designed to extend from the perimeter support  12  to the center beam  14 . The ceiling panel  20  usually just lays on top of, or appears to lay on top of, non-weight-bearing side beams  19 . Although the non-weight-bearing side beams  19  are not intended to hold any weight, they can clearly support a small fraction of the weight of the ceiling panels in which they come in contact.  
         [0035]    If the center beam(s)  14  do not have channels  16 ,  18 , the ceiling panels will also lay flat on the center beam  14 ; however, the center beam must carry at least part of the weight of the ceiling panels regardless of whether channels  16 ,  18  are present.  
         [0036]    In a ten feet by twelve feet room, the center beam  14  is placed substantially in the middle of the room between the walls  90 ,  94  (i.e., five feet from wall  90  and five feet from wall  94 ). In this example, the ceiling panels  20  are approximately two feet wide by five feet long (or more precisely, five foot minus about one-quarter of the width of the center beam). This ensures that each ceiling panel  20  has the length to extend from a weight-bearing side beam  12  to the center beam  14 .  
         [0037]    Again, using the example of a ten feet by twelve feet room and one center beam  14 , if the ceiling panels are two feet in width, it will take six ceiling panels to cover one column (or one half of the ceiling A) and an additional six ceiling panels to cover the remaining column (or the other half of the ceiling B). In this example (i.e., a ten by twelve room with two by five ceiling panels), a total of twelve ceiling panels will be required.  
         [0038]    In another example, if the room is fifteen feet by twelve feet in dimension, one may decide to use one center beam  14  at the seven and half foot mark with two columns of ceiling panels  20 , wherein each ceiling panel is seven and half feet long. In the alternative, two “center” beams  14  may be used, placing the first center beam at the five feet mark and the second center beam at the ten feet mark, while the ceiling panels  20  are five feet in length. (It should be noted that in this last example, the ceiling panels  20  are the same width and length as the ceiling panels in the ten feet by twelve feet room example. It would be a manufacturing advantage to standardize the sizes of most of the components including the ceiling panels.)  
         [0039]    Of course, in the example of a 15′ by 12′ room with two center beams, three columns of ceiling panels will be required to cover the entire ceiling. Column A would extend from weight bearing side beam  12  on first wall  90  to the first center beam, column B would extend from the first center beam to the second center beam, and column C would extend from the second center beam to the weight-bearing side beam  12  on wall  94 .  
         [0040]    It will be apparent to one skilled in the art, after reading the present disclosure, to design the suspended ceiling in such a way to suit a particular need, to accommodate the installer, to accommodate the existing ceiling or to minimize the amount of material (e.g., wood) required to cover the ceiling.  
         [0041]    Referring now to FIGS. 4 and 5, in a preferred embodiment, each ceiling panel  20  is made from three flat boards  22 ,  24 ,  26 , having a lap joint  40  construction along their edges. A top lap  40 A on one flat board would mate with the bottom lap  40 B of an adjacent flat board.  
         [0042]    A plurality of support members  28  are used to secure the three flat boards  22 ,  24 ,  26  together into a single ceiling panel  20 . In a preferred embodiment, the support members  28  are made of wood but can be made from plastic, metal or any material that can provide the necessary strength to maintain the rigidity of the ceiling panels.  
         [0043]    A plurality of wood screws  46  are used to attach support member  28  to the back side of the ceiling panels  20 . It would be obvious to one skilled in the art, after reading the present disclosure, to make the ceiling panels using a number of different construction methods and techniques. For example, the lap joint construction is not necessary; some people believe that a tongue-and-groove construction, biscuit joint or other construction gives the ceiling a more professional and finished appearance.  
         [0044]    Referring again to FIGS. 4 and 5, a rail  32  is added to the face of each ceiling panel  20 . The rail  32  is designed to communicate with rabbit joint  13  of the perimeter supports  12  as illustrated in FIGS. 3 and 7.  
         [0045]    Second rail  33  is secured to the opposite end of the ceiling panels  20  and are designed to communicate with channel  16  (or channel  18  depending on which column the ceiling panel is placed) of the center beam  14 . The second rail  33  is spaced away from the first rail  32  so that when first rail  32  is inserted into rabbit joint  13  second rail  33  is inserted into channel  16 .  
         [0046]    When one rail or both rails are properly seated, they are designed to limit the linear movement in one direction and the rotational movement of the ceiling panels. This resists the accidental displacement of the ceiling panels  20 .  
         [0047]    A feature of the present invention is that the total appearance of the room may be changed by replacing a few (or all) of the ceiling panels with new ceiling panels. Also, the original ceiling panels may be altered by painting, staining or changing the appearance of the ceiling panels by drilling/carving/machining various designs into the wood or forming a specific pattern into the ceiling panels. Moreover, individual flat boards ( 22 ,  24  or  26 ) may be altered instead of changing the entire ceiling panel.  
         [0048]    Referring again to FIG. 3, perimeter supports  12  are shown mounted on their respective diametrically opposed walls  90 ,  94 . Support joists  38  from the existing non-finished ceiling are shown running perpendicular to the center beam  14  and weight-bearing side beams  12 . One or more L-shaped brackets  36  are attached to the back side of the center beam  14  and suspended from the support joists  38 . A better view of an L-shaped bracket is shown in FIG. 6.  
         [0049]    The direction in which the center beam  14  and the weight-bearing side beams  12  ultimately run will depend on an analysis of the room, including the type of pre-existing ceiling, location of pipes, HVAC duct work, and electrical wires, the location and position of support joists, and similar factors.  
         [0050]    The L-shaped brackets  36  are particularly desirable to support the center beam  14  when the center beam  14  is designed to hang perpendicular to joists  38 . If the joists  38  are made of wood, screws  44  or nails may be used to secure the L-shaped brackets  36  to the joists  38 .  
         [0051]    The suspended ceiling system  10  should be laid out by the installer initially. Some of the decisions that need to be made by the installer are which walls the weight-bearing beams  12  will be attached, the number of center beams, the approximate location/orientation of the center beams  14  and the size and number of ceiling panels  20  needed to cover the ceiling. The non-weight bearing beams  19  will be secured to the remaining two diametrically opposed walls.  
         [0052]    Although ceiling panels  20  are shown with two rails  32 ,  33 , in a preferred embodiment each ceiling panel only requires one rail  32  for communicating with the rabbit joint  13  in perimeter supports  12 . One end of the ceiling panel is meant to be raised and at least partially maneuvered above the center beam  14 ; the remaining end is raised while simultaneously sliding the remaining end back over the perimeter supports  12  so that first rail  32  aligns with and drops into rabbit joint  13 .  
         [0053]    In another embodiment, the ceiling panels  20  may be equipped with a second rail  33  on the side opposite first rail  32 . The second rail  33  is designed to communicate with either channel  16  or channel  18 . In this embodiment, the second end of each center panel  20  is slid above and over the center beam  14 , the first end is then raised above the perimeter support  12 , the entire ceiling panel is then slid back towards the perimeter support  12  until first rail  32  is above and dropped into rabbit joint  13 , while the second rail  33  drops into its respective channel  16 . The combination of the first rail  32  and rabbit joint  13  along with the combination of the second rail  33  and the channel  16  “locks in” the ceiling panel.  
         [0054]    The rails  32 ,  33  do not necessarily have to carry a significant amount of weight. However, the rails may be subject to a perpendicular or rotational force when someone attempts to move the ceiling panels  20 . The rails  32 ,  33  are typically made of wood but may be manufactured from the same materials as the support members  28 . Depending on the materials used to manufacture the rails, they may be attached to the flat boards by wood screws, tacking, gluing or other means known in the industry.  
         [0055]    As indicated previously, the ceiling system  10  preferably utilizes only one rail  32 . However, this one rail is sufficient to prevent the accidental displacement of the ceiling panels. A second rail  33  will further secure each ceiling panel so that only an intentional manipulation (and in a specific manner also) of the ceiling panel will dislodge it.  
         [0056]    The use of one or both rails is an important feature of this invention. The ease of installation and the ease of changing the appearance of the entire ceiling system by replacing or manipulating a few flat boards are other features.  
         [0057]    Although this invention has been described and illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made which clearly fall within the scope of this invention. The present invention is intended to be protected broadly within the spirit and scope of the appended claims.

Summary:
A ceiling, preferably made of wood, to be suspended from an existing ceiling of a room comprising a plurality of perimeter support members adapted to be attached to antipode walls of the room. The perimeter supports having a rabbit channel along their top edge. The suspended ceiling including a center beam having inner side and an outer side, the inner side designed to face the interior of the room, the outer side of the center beam having a pair of channels extending along the longitudinal dimension of the center beam, a brace designed to attach to the outer side of the center beam for fixedly attaching the center beam in a pre-determined location to the ceiling, and a plurality of ceiling panels designed to extend from (and supported by) the perimeter supports and the center beam. Each ceiling panel has at least one rail attached to the front side for communicating with a rabbit joint on the perimeter supports for securing the ceiling panel. If the ceiling panel has a second rail, it is used to communicate with the channel on the center beam further restricting movement of the ceiling panel.  
     It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.