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CROSS-REFERENCE TO RELATED APPLICATION 
     This United States patent application relates to and claims priority from Canadian patent application number 2,588,300, filed on Apr. 30, 2007, entitled MEDIUM DENSITY FIBERBOARD (MDF) SUSPENDED CEILING, which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to ceilings and more precisely to suspended ceilings. The invention more precisely relates to a kit of parts adapted to be assembled to form a ceiling. 
     BACKGROUND OF THE INVENTION 
     Suspended ceilings are usually made of a metal grid consisting of longitudinal parallel runners spaced apart from one another a desired distance and separated by cross members in a perpendicular fashion thereby creating a plurality of rectangular openings. In general, those rectangular openings are of standard sizes allowing the ventilation outlets and the lighting fixtures to be easily inserted among the ceiling panels. 
     Suspended ceilings have been mostly utilized in office buildings and in housing basements because of the handiness that such systems allow to repair and/or to modify the partition of the space. However, most development in suspended ceilings has been towards improving the convenience for offices, without any improvement to the visual aspect of the ceiling. 
     Indeed, the typical ceiling panels are made of fibrous material with a flat bottom finish, which are inserted in the rectangular openings made of the metal grid as disclosed in U.S. Pat. No. 2,971,617, No. 3,385,021 and No. 3,785,110. Such unappealing designs have restricted the installation of suspended ceilings in residential construction to the basement and hinder their distribution whenever an upscale finish is desired. 
     To improve the appearance of the conventional suspended ceilings, wooden or wood-like grid systems have been reported in U.S. Pat. Nos. 3,583,119, 3,557,506, 4,454,700, 4,281,498, 4,367,616, 4,452,021, 4,464,876, 4,525,971, 4,773,200, 5,218,808, and 7,010,895. Installation of such ceiling systems usually required additional manipulations and was used in conjunction with the conventional flat bottom fiberboard panels 
     Therefore, a need has been found for an improved suspended ceiling. Similarly, a need has arisen for an improved suspended ceiling that is inexpensive to produce and easy to install. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention provides an improved modular ceiling over the prior art. 
     This invention relates to an easy-to-install suspended ceiling system and more specifically to the MDF composition of the panel, runners and cross members, which procure an aesthetical look. 
     One aspect of the present invention provides a modular ceiling comprising a plurality of runner members, cross members, Ogee and panels. 
     Another aspect of the present invention provides the runner member with a longitudinal retaining cavity on its upper surface to hang the runner member via a fastener engaged in the longitudinal retaining cavity. 
     Another aspect of the present invention provides the runner member with a longitudinal groove on its upper surface to secure corresponding cross members thereto. 
     One other aspect of the present invention provides a cross member with a longitudinal retaining cavity on its upper surface to receive a fastener adapted to engage the groove of the runner member. 
     Yet another aspect of the invention provides an Ogee member adapted to interface the ceiling with a wall, the Ogee member having a longitudinal retaining cavity defined thereon to hang the Ogee member via a fastener engaged in the longitudinal retaining cavity. 
     One aspect of the present invention provides a fastener adapted to mate with the longitudinal retaining cavity on one side and to connect to a support on the other side, the connection with the support also provides further vertical adjustment. 
     Another aspect of the invention provides an upper runner and a lower runner adapted to, in combination with a panel, change the vertical height of the ceiling from a first vertical height to a second vertical height. 
     One other aspect of the invention provides modular ceiling comprising a first main runner defining an upper surface and a lower surface, the upper surface defining a longitudinal retaining cavity along the first main runner and at least one recess provided on each side of the longitudinal retaining cavity; a second main runner adapted to be disposed parallel to the first main runner when assembling the modular ceiling, the second main runner defining an upper surface and a lower surface, the upper surface defining a longitudinal retaining cavity along the second main runner and at least one recess provided on each side of the longitudinal retaining cavity; a cross member installable at an angle from the main runners and adapted to connect the first main runner with the second main runner, the cross member being secured to the main runners by a cross member fastener having a cross runner anchor adapted to engage the recess defined in the main runners; and a panel adapted to be disposed between main runners and being supported, at least in part, by the main runners. 
     Another aspect of the invention provides a method for installing a modular ceiling, the method comprising suspending a first main runner defining an upper longitudinal retaining cavity along the first main runner, to suspend the first main member, the first main runner defining a recess and a lip on each side of the longitudinal retaining cavity; suspending a second main runner parallel to the first main runner, the second main runner defining an upper longitudinal retaining cavity along the second main runner, to suspend the first main member, the first main runner defining a recess and a lip on each side of the longitudinal retaining cavity; installing a cross member between the first and the second main runners; and securing a panel between the main runners by engaging the lips of the main runners. 
     One other aspect of the invention provides a kit for building a ceiling, the kit comprising a plurality of main runners, each main runner defining an upper longitudinal retaining cavity and a recess defined on each side of the longitudinal retaining cavity; a plurality of cross runners adapted to connect the main runners together; and a plurality of panels adapted to be disposed between the main runners and being supported by the main runners, the plurality of panels being adapted to be positioned relative to the main runners by the recesses defined in the main runners. 
     Embodiments of the present invention do not necessarily have all of the above-mentioned objects and/or aspects. 
     Additional and/or alternative features, aspects, and advantages of the embodiments of the present invention will become apparent from the following description, the accompanying drawings, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective bottom view of the suspended ceiling of the present invention, wherein the plurality of runners and cross members gives rise to a lattice defining openings that can accommodate the profiled panels as well as the ventilation outlets and the lighting fixtures, if required; 
         FIG. 2  is a cross sectional view of a runner; 
         FIG. 3  is a three dimensional view of the runner of  FIG. 2 ; 
         FIG. 4  is a cross sectional view of a cross member; 
         FIG. 5  is a three dimensional view of the cross member of  FIG. 4 ; 
         FIG. 6  is a cross sectional view of an optional ogee runner adapted for installation in the periphery of the lattice along the wall; 
         FIG. 7  is a cross sectional view of a ceiling anchor; 
         FIG. 8  is a three dimensional view of the ceiling anchor of  FIG. 7 ; 
         FIG. 9  is a cross sectional view of a dovetail runner anchor that is inserted into the runner dovetail groove; 
         FIG. 10  is a three dimensional view of the dovetail runner anchor of  FIG. 9 ; 
         FIG. 11  is a cross sectional view of the assembly of the dovetail runner anchor to the ceiling anchor of  FIGS. 7 and 9 ; 
         FIG. 12  is a three dimensional view of a cross member anchor; 
         FIG. 13  is an overall view of the anchoring system that allows the runner and cross member to be secured to an overhead structure of the building; and 
         FIGS. 14 and 15  are cross sectional views of optional lower and upper runners adapted specifically to be used together for the addition of vertical panel. 
     
    
    
     The features of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein: 
     DETAILED DESCRIPTION OF THE INVENTION 
     The preferred embodiment illustrated in the Figures is one possible mechanical arrangement among other workable variations. These other workable variations are not considered to be enough materially distinctive so that a person skilled in the art of ceiling manufacturing and installation would not know how to adapt the present invention thereto. 
       FIG. 1  illustrates a suspended ceiling  22  built with a series of main runners  1  and cross members  2  in a lattice pattern. The surface covered by the modular ceiling  22  and the distance between main runners  1  and cross members  2  can also vary in accordance with the desired visual effect. On  FIG. 1  the cross members  2  are illustratively alternated on each side of the main runners  1  but they could also be aligned. Panels  4  are installed in the openings formed by the lattice of main runners  1  and cross members  2 . 
     Referring to  FIGS. 2 and 3  it is appreciated that the main runner  1  has an upper surface  24  facing the upper side of the room and a lower surface  26  facing the floor of the room in which the ceiling  22  is installed. The upper surface  24  comprises a longitudinal retaining cavity  5  preferably disposed in the center of the main runner  1 . The longitudinal retaining cavity  5  is adapted to receive a fastener to suspend the main runners  1 . The longitudinal retaining cavity  5  is preferably shaped to receive a fastener  36  having a dovetail shape  28  to easily secure the fastener  36  in the longitudinal retaining cavity  5 . The dovetail shape  28  allows a strong and safe connection with the associated longitudinal retaining cavity  5 . 
     The upper surface  24  also comprises two grooves  6  respectively disposed on each side of the longitudinal retaining cavity  5 . The longitudinal retaining cavities  5  are adapted to position and secure the cross members  2  to the main runners  1 . The fastening mechanism will be detailed later in the description. 
     Additionally the upper surface  24  defines two lips  7  disposed on each side of the upper surface  24  to receive and support the cooperating edge of the panel  4 . 
     The longitudinal retaining cavity  5 , the two grooves  6  and the lips  7  can be produced with the main runner  1  using an extrusion process given the main runner  1  can be made of plastic or aluminum. The longitudinal retaining cavity  5 , the two grooves  6  and the lips  7  can alternatively be manufactured by adding portions of material on top of the bottom portion of the main runner  1  that is a rectangle. The additional portions of material can be glued or hot-welded depending on the process that is used. 
     The size of the main runner  1  is compact with its ˜75 mm width to keep to a minimum the thickness so that the space needed above the main runner  1  is reduced to maximize the height of the room in which the ceiling is installed. 
       FIGS. 4 and 5  illustrate the cross member  2  in isolation. It can be appreciated that the cross member  2  also has an upper surface  24   a  and a lower surface  26   a . A longitudinal retaining cavity  5   a  and two lips  7   a  are also provided in the upper surface  24   a  of the cross member  2 . A longitudinal extension  30  is provided at each end of the cross member  2 . The longitudinal extension  30  is adapted to mate with the lip  7  of the main runner  1  thus providing support to the cross member  2 . The same materials and manufacturing processes used for manufacturing the main runners  1  are suitable to manufacture the cross members  2 . 
     An ogee  20  is depicted on  FIG. 6 . The ogee  20  is a support member just as the main runner  1  and the cross member  2  with the difference that it is used where the ceiling  22  reaches a wall  32 . The ogee  20  comprises a longitudinal retaining cavity  5   b  and a lip  7   b  that are similar to the above-described longitudinal retaining cavity  5 / 5   a  and lip  7 / 7   a  of the main runner  1  and of the cross member  2 . The ogee  20  is secured to the wall with fasteners (i.e. nails, screws, . . . ), the fastener  36  using the longitudinal retaining cavity  5   b  or glued at the right height so that the ogee  20  can receive and support the adjacent cross members  2  and panels  4 . The ogee  20  is manufacturable with similar materials and processes as the main runners  1 . 
       FIG. 7  and  FIG. 8  illustrate an illustrative cooperating part to the fastener used to suspend the main runner  1  and the cross member  2  by their longitudinal retaining cavity  5 . The cooperative part shown on  FIGS. 7 and 8  is a T-shaped support  34  adapted to be secured to a trust via holes  35  defined in a horizontal portion  8  of the T-shaped support  34 , an above-ceiling structure  38  and also connects to the fastener  36 . The T-shaped support  34  permits height adjustment by securing the corresponding fastener  36  at the right position with the holes  9  present in the vertical portion  33  of the T-shaped support  34 . 
     One can appreciate from  FIG. 9  and  FIG. 10  that the fastener  36  defines a shape adapted to cooperate with the longitudinal retaining cavity  5 . In the present situation the shape provided by the fastener  36  is the male dovetail shape  29  adapted to cooperate with the female counterpart  28  that is the properly shaped longitudinal retaining cavity  5 . The fastener  36  defines a vertical section  37  having a plurality of slots  10  adapted to receive a fastener to be secured to an associated connection member  34  (in the present situation, the T-shaped support  34 ) with a bolt or a screw  13  as shown on  FIG. 11 . The fastener  36  can be produced in plastic or aluminum with a proper extrusion process. 
       FIG. 12  refers to a cross member fastener  40  defining on one side a shape  28   29   a  adapted to mate with the longitudinal retaining cavity  5   a  of the cross member  2  and defining on the opposite side a cross member anchor  12  adapted to engage the groove  6  of the runner  1 . In the present example the dove tail  29   a  shaped side of the fastener  40  is inserted in the longitudinal retaining cavity  5   a  of a cross member  2  and the cross member  2  is positioned next to a runner  1  to insert the cross member anchor  12  in the groove  6  of the runner  1  to secure the cross member  2  to the runner  1 . The longitudinal extension  30  of the cross member  2  is adapted to rest on the lip  7  of the runner  1  to help transfer the load of the cross member  2  (and the panel  4  resting on the cross member) to the runner  1 . 
       FIG. 13  illustrates an assembly of two cross members  2  with an adjacent runner  1 . It can be appreciated that each cross member  2  uses a cross member fastener  40  engaging both the longitudinal retaining cavities of the cross member  2  and the groove  6  of the runner  1 . The runner  1  is hung to the above-ceiling structure  38  with the fastener  36  engaged on one side with the longitudinal retaining cavity  5  of the runner  1  and to the T-shaped support  40  on the other side. 
     Turning now to  FIG. 14  and  FIG. 15  displaying respectively an upper runner  42  and a lower runner  44 . The upper runner  42  and the lower runner  44  are generally used collectively to change the direction of the ceiling from the usual horizontal position  46  to a vertical position  48  and back to a horizontal position  50  in order to manage a change in height of the ceiling. The upper runner  42  provides, on a first side, a longitudinal retaining cavity  5   c  to secure the upper runner  42  and a lip  7   c  to receive a panel  4 . In contrast the second side provides a groove  15  adapted to accommodate the panel  4 . Similarly, the lower runner  44  provides, on a first side, a lip  7   d  to support a panel. The second side of the lower runner  44  provides a groove  15   a  adapted to accommodate the panel  4 . These runners  42 ,  44  can be suspended or directly secured to a beam or any suitable member using fasteners or glue. 
     Although the invention has been described with reference to certain specific embodiments, various modifications and improvements thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto. The entire disclosures of all references recited above are incorporated herein by reference.

Summary:
A modular ceiling comprising first and second main runners defining an upper surface and a lower surface, the upper surface defining a longitudinal retaining cavity along the first main runner and two grooves disposed parallel to and, respectively, on each side from the longitudinal retaining cavity; a cross member installable at an angle from the main runners and adapted to connect the first main runner with the second main runner, the cross member being secured to the main runners by a cross member fastener having a cross runner anchor adapted to engage the groove defined in main runners; and a panel adapted to be disposed between main runners and being supported, at least in part, by main runners.