Abstract:
A suspended ceiling elongate grid tee having a lower flange, a vertical web, and an upper hollow reinforcing bulb, at least some of the flange, web and bulb elements, having relatively flat exposed or accessible surfaces, and a plurality of pairs of conductors attached to said flat surfaces and extending along substantially the full length of the tee whereby grid tee is capable of carrying at least two fully independent DC circuits.

Description:
[0001]    This application claims the priority of U.S. Provisional Application No. 61/118,062, filed Nov. 26, 2008. 
         [0002]    The invention relates to suspended ceiling structures and, in particular, to electrification of such ceiling structures. 
       BACKGROUND OF THE INVENTION 
     Prior Art 
       [0003]    Commercial building spaces such as offices, laboratories, light manufacturing facilities, health facilities, meeting and banquet hall facilities, educational facilities, common areas in hotels, apartments, retirement homes, retail stores, restaurants and the like are commonly constructed with suspended ceilings. These suspended ceiling installations are ubiquitous, owing to their many recognized benefits. Such ceilings ordinarily comprise a rectangular open grid suspended by wire from a superstructure and tile or panels carried by the grid and enclosing the open spaces between the grid elements. The most common form of grid elements has an inverted T-shaped cross-section. The T-shape often includes a hollow bulb at the top of the inverted stem of the T-shape. A popular variant of this standard T-shape includes a downwardly open C-shaped channel formed by the lower part of the inverted tee. 
         [0004]    Advances in electronics has fed further advances and lead the world into the digital age. This digital movement creates an ever-increasing demand for low voltage direct current (DC) electrical power. This demand would seem to be at least as great in finished commercial space as any other occupied environment. A conventional suspended ceiling has potential to be an ideal structure for distributing low voltage electrical power in finished spaced. Many relatively low power devices are now supported on such ceilings and newer electronic devices and appliances are continuously being developed and adopted for mounting on ceilings. 
         [0005]    The ceiling structure, of course, typically overlies the entire floor space of an occupiable area. This allows the ceiling to support electronic devices where they are needed in the occupied space. Buildings are becoming more intelligent in energy management of space conditioning, lighting, noise control, security, and other applications. The appliances that provide these features including sensors, actuators, transducers, speakers, cameras, recorders, in general, all utilize low voltage DC power. 
         [0006]    As the use of electronics grows, the consumption of low voltage electrical power likewise grows. This seemingly ever accelerating appetite for DC power presents opportunities for more efficient transformation of relatively high voltage utility power typically found at 110/115 or 220/240 alternating current (AC) volts with which the typical enclosed space is provided. Individual power supplies located at the site of or integrated in an electronic device, the most frequent arrangements today, are often quite inefficient in transforming the relatively high voltage AC utility power to a lower DC voltage required by an electronic device. Typically, they can consume appreciable electric power in a standby mode when the associated electronic device is shut off. It is envisioned that a single DC power source serving the electronic needs of a building or a single floor of a building can be designed to be inherently more efficient since its cost is distributed over all of the devices it serves and because it can take advantage of load averaging strategies. 
         [0007]    Thus, grid tees used in suspended ceilings, with little added cost, can provide a medium for electrifying the entire ceiling area, including the space immediately above, the plane of the ceiling space, and the space immediately below the ceiling with low voltage power. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention comprises a grid tee member having a plurality of separate low voltage electrical circuits each effectively running its full length. The circuit conductors can be individually accessed at substantially any point along the length of the tee for receiving or supplying electrical power. Each of the conductors can be joined at the ends of its respective tee to corresponding conductors on other tees to provide full electrification of a suspended ceiling. Ideally, the circuits are each formed by a flat strip of a conductive ink or like coating or a metal foil or tape. The invention lends itself to use with conventional roll formed sheet metal grid tees. The conductive strips can be applied to the strip stock of the tee before, during or after the roll forming process. 
         [0009]    The relatively low voltage and power requirements of typical solid state ceiling mounted appliances, enable the strips to be comparatively inexpensive and unobtrusive since they and any related insulating layers require little material content. By making the conductive strips relatively wide, and locating them widely spaced over the exposed or accessible surfaces of the tee permits use of low cost connectors or terminals of loose dimensional tolerances. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a cross-sectional view of a generalized conventional grid tee of a first style provided with a first arrangement of longitudinally extending electrical conductors; 
           [0011]      FIG. 2  is a cross-sectional view of a generalized conventional grid tee of a second style provided with another arrangement of longitudinally extending electrical conductors; 
           [0012]      FIG. 3  is a cross-sectional view of the first style of grid tee with a variation in the arrangement of longitudinally extending electrical conductors; 
           [0013]      FIG. 4  is a cross-sectional view of the first style of grid tee with still a further arrangement of longitudinally extending electrical conductors; 
           [0014]      FIG. 5  is a cross-sectional view of the second style of grid tee with a still further example of a pattern of longitudinally extending electrical conductors; and 
           [0015]      FIG. 6  is yet another example of an arrangement for multiple circuits on the second style of grid tee. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0016]    In  FIGS. 1-6 , two generally conventional styles of suspended ceiling grid tees  10 ,  11  are represented by their cross-sections.  FIGS. 1 ,  3  and  4  illustrate a two-piece tee  10  having a main body  12 , with diverging portions  13  of a horizontal lower flange  14 , a double layer vertical stem or web  16 , and a hollow reinforcing bulb  17  forming its upper part. A separate cap  15  is assembled on the lower faces of the flange portions  13 .  FIGS. 2 ,  5  and  6  illustrate a single piece tee  11  having a lower flange  21  in the form of a downwardly open C-shaped channel, a double layer vertical stem or web  16 , and a hollow upper reinforcing bulb  17 . The tees  10 ,  11  can represent both main runners and cross runners, terms used in the art to designate, respectively, long elements (nominally 12 or 10 feet or metric equivalent) joined end-to-end and shorter elements (nominally 2 or 4 feet or metric equivalent) that bridge the space between parallel main runners. Most commonly, the tees  10 ,  11  are manufactured of prepainted steel strip by roll-forming techniques. It will be understood, however, that other forming techniques such as an extrusion process can be used and other materials such as aluminum or plastics can be used to produce the tees  10 ,  11 . 
         [0017]    The figures illustrate electrical conductors  26  in the form of flat strips fixed to various exposed surfaces of the grid tees  10 ,  11 . The conductors  26  in the illustrated examples are relatively flat strips, typically being much thinner than the proportions illustrated in these figures for purposes of illustration. The strips  26  in one economical form are bands or traces of printed conductive ink. Such ink is available commercially from T-Ink, Inc. of New York, N.Y. USA. One convenient way of fabricating the grid tees  10 ,  11  is to roll form their respective shapes from flat metal stock, typically steel. While the metal stock strip is flat, its eventual exposed surface can be coated with an insulating material by known techniques such as roll coating, spraying, powder coating, or like process using known electrically insulating materials. The side of the sheet stock that will bear the conductive strips  26  is either completely coated with electrically insulating material, or is coated with bands where the conductive strips will be applied. Alternatively, insulating material can be applied locally to the surfaces in question after the tee  10  or  11  has been formed. As another alternative, the conductive strip material where it is a foil or tape can be coated or laminated with an electrically insulating material at least on its side that will face towards the grid tee. In the latter case, for example, an adhesive can be applied to the underside of the insulator of the conductive strip  26  or can be applied to the tee  10  or  11  thereby permitting the conductive strips  26  to be permanently attached to the grid tee. 
         [0018]    Over coating or over laminating the conductive strip whether it be a conductive ink trace or a metal foil or tape, is optional, if not preferred. Inspection of  FIGS. 1 and 2  reveals that the conductors  26  are attached to generally flat exposed or (in the case of the flange  21  of the tee  11 ) accessible surfaces of the respective tees  10 ,  11 . As shown in  FIGS. 1 and 2 , the arrangement or pattern of the conductive strips  26  need not be symmetrical with a central vertical plane through the respective tee  10 ,  11 . It will be understood that in the illustrated arrangements, each of the conductive strips  26  is electrically isolated from the remaining strips on a particular tee  10 ,  11 . Moreover, where the tee  10  or  11  is formed of a metal, such as steel or aluminum, as is typical, the body of the tee can be used as a common pole at a voltage polarity opposite the polarity of voltage applied to one or more conductors  26 . 
         [0019]      FIGS. 3-6 , inclusive, illustrate grid tees  10 ,  11  on which individual local pairs of conductors  27 ,  28  are provided. It will be seen that the conductors can be arranged in pairs that are symmetrically disposed on the grid tee about its central vertical plane or can be asymmetrically arranged. Additionally, the pairs of conductors can be either immediately adjacent each other, or can be spaced from one another. For example, in the embodiments of  FIGS. 4 and 6 , certain pairs of the conductors are on opposite sides of a central vertical plane of the tee. Like the conductors  26  described in connection with  FIGS. 1 and 2 , the conductors  27 ,  28  can be provided in a variety of forms including conductive ink traces, metal foils or tapes. 
         [0020]    The conductors of each pair  27 ,  28 , will normally be operated at opposite polarities. It will be understood that the individual conductors  26  in the arrangements of  FIGS. 1 and 2 , and the pairs of conductors  27 ,  28  in  FIGS. 3-6  permit as many independent circuits as conductors  26 , or pairs of conductors  27 ,  28  exist on a given tee  10  or  11 . Where desired, the conductors  26 , and pairs of conductors  27 ,  28  can be operated at different voltage levels to satisfy the needs of particular digital or electronic devices. Further, it will be seen, that voltage can be supplied to devices that exist below, at, or above the plane of the ceiling. 
         [0021]    It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.