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: 
This application claims the priority of U.S. Provisional Application No. 61/118,058, filed Nov. 26, 2008. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to suspended ceiling structures and, in particular, to electrification of such ceiling structures. 
     PRIOR ART 
     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. 
     Advances in electronics has fed further advances and led 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. 
     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, and recorders, in general, all utilize low voltage DC power. 
     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. 
     SUMMARY OF THE INVENTION 
     The invention permits and augments the practical and versatile use of the grid elements of a conventional style suspended ceiling to supply and distribute low voltage electrical power to the area of a building with which it is associated. In accordance with the invention, a grid runner or tee of generally conventional cross-sectional shape is employed as a rigid carrier for one or more pair of conductors or as a conductor or conductors itself. 
     As disclosed, the conductors can be conductive inks, metal foils, metal tapes, metal wires, or the components of a grid tee or combinations of these elements. A conductor, where it is distinct from the structure of a tee itself, can be located along various surfaces of a tee either in symmetrical or non-symmetrical relation to a central vertical plane of symmetry of the tee. In numerous disclosed embodiments, a conductor can be economically formed in situ as an ink trace deposited on the structure of a tee. This ink trace can be formed before or after a tee is roll-formed into a finished shape from a sheet metal strip. Similarly, a conductive foil, tape, or wire can be fixed onto the strip stock or formed tee. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a conventional grid tee; 
         FIG. 2  is a cross-sectional view of a conventional modified form of grid tee; 
         FIG. 3  is a cross-sectional view of a novel modified form of grid tee useful in providing an electrified grid according to the invention; 
         FIGS. 4A-4E  are grid tee cross-sections with discrete electrical conductors symmetrically arranged on opposite sides of a central vertical plane; 
         FIGS. 5A-5D  are cross-sectional views of grid tees having pairs of conductors asymmetrically arranged with respect to the mid-plane of a respective grid tee; 
         FIGS. 6A-6C  are cross-sectional views of grid tees having parts of their bodies separated by an electrical insulator to form separate conductive circuit paths without additional conductors; 
         FIG. 7  is a cross-sectional view of a grid tee  30  having a multiplicity of conductors; 
         FIG. 8  is a fragmentary isometric view of a grid tee and separately formed insulator cap and wire assembly; 
         FIG. 9  is cross-sectional view of a grid tee fitted with an assembly of conductive and non-conductive layers; 
         FIG. 10  is a view similar to  FIG. 3  including a diagrammatic showing of a connector assembly; 
         FIG. 11  is a fragmentary isometric view of a grid tee similar to that shown in  FIG. 6C ; 
         FIG. 12  is a cross-sectional view of a grid tee with a conductive path within the web or stem of the tee; 
         FIG. 13  is a diagrammatic representation of a cross-section of a grid tee having conductive ink traces and a clip used to establish a connection to feed or draw power from such traces; 
         FIG. 14  illustrates a grid tee with conductors running vertically on a grid tee; 
         FIG. 15  is a fragmentary isometric view of a grid tee  10  having multiple easily tapped conductors; 
         FIG. 16  illustrates a grid tee with a flange over-cap carrying conductive traces; and 
         FIG. 17  illustrates a grid tee made of electrically insulating material. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 4A , discrete electrical conductors  11 ,  12  are fixed to the upper sides of a flange  13  of a grid runner or tee  10  of conventional cross-section. The numeral designation  10  will be used throughout the following disclosure when reference is made to a grid tee of standard configuration. As is customary, the structural body or mass of the tee  10  is roll-formed from metal sheet stock, typically steel. The tee cross-section includes an upper hollow reinforcing bulb  14  and a separate cap  16  folded at its edges over flange elements diverging from a double layer stem  18  extending up to the bulb  14 , as is customary. The separate strips forming the tee proper and the cap can be prepainted or coated with a protective film before they are rolled to their finished shape. The conductors  11 ,  12  in this and other embodiments can take various forms including strips of conductive ink, metal foil, or tape of copper, brass, or aluminum, for example, or single or multi-strand wire running longitudinally with the length of the tee. The conductors  11 ,  12  are fixed to underlying areas of the tee with a suitable adhesive which may serve as an electrical insulator and prevent electrical contact between the conductor  12 ,  13  and tee  10 . Alternatively, a separate electrically insulating medium may be applied to either the tee  10  or conductor  11 ,  12 , apart from the adhesive medium therebetween. It is contemplated that the protective coating applied to the sheet material of the tee can serve as the requisite insulator. Still further, the exposed surfaces of the conductors  11 ,  12 , i.e. those surfaces not facing the upper side of the flange  13  or other tee parts in other embodiments, can be covered with suitable insulating material to resist short circuiting against metal objects when a tee is installed in a ceiling structure. As depicted in  FIGS. 4A-4E , the conductors  11 ,  12  can be situated in numerous locations. In  FIGS. 4C-4E , the grid cross-section or profile is of the conventional downwardly open C-shaped channel type. In  FIGS. 4C and 4E , the conductors are permanently placed in the hollow of the bottom channel against respective flat interior surfaces of the tee. In these latter figures, the tee is designated by the numeral  20 . 
     Unless indicated differently, it will be understood that a conductor that is separate from a tee  10 ,  20 , will be adhesively secured to the tee, or otherwise permanently affixed thereto, and will be electrically isolated therefrom. 
     As shown in  FIGS. 5A-5D , the conductors  11 ,  12  can be arranged in asymmetrical patterns, when viewed along the longitudinal direction of a grid tee. Such arrangements can be used, for example, to assure proper assembly of grid elements and electrical connectors. 
     It is contemplated that any of the arrangements of  FIG. 4  or  FIG. 5  can be modified by eliminating one of the pair of conductors  11 ,  12 , and by using the body of the tee  10  or  20  as the second conductor. Most commonly, the grid tees  10  or  20  will be formed of sheet steel, however, aluminum may be used and such aluminum may be extruded if not roll-formed. In the case of the two-piece tee  10 , either the main body (that is, the upper flange elements  17 , double layer stem  18 , and bulb  14 ) or the cap  16 , can constitute the conductor individually or collectively. Where an electrical connection is to be made to the tee  10  or  20  directly, the protective paint or coating applied to it will be locally omitted or removed to expose a conductive area. Where convenient or necessary, a brass or copper terminal can be attached to the conductive exposed area of the tee  10 ,  20 . 
     With reference to  FIG. 6A , the grid tee cap  16  is isolated from a main body  15  of the tee  10  by insulating material  26  thereby allowing the cap to afford one conductive path or conductor and the main body  15  to provide the other conductive path or conductor. In  FIG. 6B , the main body  15  is bisected by insulating material  26  so that the left and right sides of this tee element provide separate conductive paths or conductors. 
     Regarding the arrangement of  FIG. 6A , either the body  15  or the cap  16  or both can be provided with a conductive trace of conductive ink, metal foil, or metal tape or wire. Such conductor can be electrically insulated from the respective body or cap element or can be in electrical contact with it to complement its current capacity. 
     It will be understood that suitable terminals, connectors, and the like will be attached to the various described grid tees conductor elements where lengths of grid tees are joined, and/or intersect and/or are tapped for power at a local electronic device, or are fed from a power supply. 
     It will be further understood that insulator layers can be coated or otherwise formed in situ or can be laminated to the respective tee element from roll stock, for example. Suitable insulating material is well known in the electrical arts. The conductive ink, in addition to using suitable metals, can employ electrically conductive non-metals including carbon. 
     The grid tee  30  illustrated in  FIG. 7  can be formed of rolled metal sheets and, in the illustrated case is without an upper reinforcing bulb. Alternatively, the tee  30  can be extruded of aluminum in one piece. The conductors  31  can be permanently affixed to a dielectric or insulator sheet  32  which is laminated or otherwise bonded to the stem of the tee  30 . The conductors  31  can be copper or brass traces, each of adequate cross-sections to carry the expected currents independently of each other. A separate upper cap  33  can be made as an extrusion of suitable dielectric material such as polyvinylchloride which is extruded or molded around a conductor in the form of a wire  34 . The conductor or wire  34  can serve as a common ground or source for the individual conductors  31 . As discussed above, the conductors  31  can be fixed to the sheet stock forming the tee  30  before the stock is roll formed into the illustrated tee shape. 
     Referring to  FIG. 8 , a grid tee  40  has the general shape of the previously disclosed tee  20 . An upper cap  41  is fixed on a reinforcing bulb  14  of the tee  40 . The cap can be an extruded thermoplastic such as PVC or other electrical insulator. The upper cap contains a wire set  42 ,  43  providing electrification of the grid tee  40 . The cap  41  can be mechanically attached to the bulb  14  of the grid tee  40  by inserting prongs  44  integrally molded on the cap into receiving apertures  46  and retained therein by a friction fit or an interference fit provided by a barb-like configuration in the prongs. It will be understood that the cap  41  or an equivalent can be provided with a single wire where the conductivity of the grid tee  40 , itself, is utilized or can be provided with a multiplicity of wires. 
     In  FIG. 9 , there is shown a grid tee having an elongated plastic bar  48  secured to the bulb  14  such as by a pressure sensitive adhesive. Typically, the bar is applied after the grid tee  10  is formed. As an alternative to adhesive fixing of the bar  48  to the tee  10 , the bar, as shown, can have a channel or C-shaped cross-section with legs fitting over the bulb  14 . On an upper surface of the bar  48  can be coated a conductive ink  49  to provide a conductor. If desired, an insulating layer  51  can be applied to the ink layer  49  and, in turn, a second ink layer  52  can be applied to the upper side of the insulating layer  51 . The reduced width of the upper conductive layer  52  and the underlying insulating layer  51  provides accessibility to the lower conductive layer  49  for suitably formed connectors for supplying or utilizing electrical power. The plastic bar  48  along with the various conductive and insulating layers  49 ,  51 ,  52 , can be applied to the tee  10  in the factory after the tee is rolled or otherwise fabricated or can be applied in the field before or after the grid is installed. 
       FIG. 10  illustrates an elongated insert assembly  56  proportioned to snap into the novel grid tee  57  shown in  FIG. 3 . The insert  56  which runs the full length of the tee  57  includes an insulating channel  58  including a web and legs. Permanently attached to the opposed legs are associated opposed conductors  62 . The conductors  62  can comprise any of the foregoing described conductor compositions. The legs are proportioned to be frictionally held or mechanically captured within the interior of the depending channel formed by the flange of the tee  57 . More particularly, hems  63  formed by folded-in edges of the sheet stock forming the tee  57  underlie the distal edges of the legs so as to mechanically capture the insert  56  within the tee channel. A connector block  55 , preferably molded of a suitable plastic is proportioned to snap into the lower channel or slot of the tee  57 . The block  55  includes a pair of opposite rounded projections  60  sized to fit in the channel and be retained therein by the hems  63 . Spring-like metal blade contacts  59  engage respective conductors  62  to transfer power to or from the conductors. Leads  61  connect the blade contacts  59  to external electric devices which can be integrated with or supported by the block  55 . 
     In  FIG. 11 , a tee  65  analogous to the tee  20  is split at its mid-plane with the left and right sides being isolated from one another by insulating material  26 . One or both halves of the tee  65  can be provided with conductors  66 . The conductors  66  can be electrically connected to their respective tee halves or can be electrically insulated from such associated halves. Where no separate conductor  66  is provided, the tee half can provide a conductive path for electrical power. 
     Referring now to  FIG. 12 , a tee  10  can be provided with a conductor in the form of a printed ink trace  71  or a conductive foil, tape, or bar. The conductor  71  can be applied to one of the layers  18  of the web with an insulator layer between it and each of the web layers. Typically, this can be done while the strip forming the tee  10  is flat. The sheet area forming the interior of the tee is first coated with an insulating layer, then the conductor layer such as the referenced conductive ink, and then an overcoat insulator layer. One or both of the stem or web layers  18  can be perforated during the tee forming process to provide access to the conductor  71 . 
     With reference to  FIG. 13 , two conductive ink traces  76  are formed over electrically insulated areas of the bulb  14  of a tee  20 . A plastic electrically insulating clip  77  maintains electrical contacts  78  against the pair of traces  76 . The contacts  78  have wire leads  79  adapted to feed power to the traces  76  or to draw power from the same. 
     Referring to  FIG. 14 , a tee  10  has one or more conductors  81  running vertically from the top of the bulb  14  to the lower flange  13 . The conductors  81  can, for example, be printed with conductive ink over suitable insulating layers. In appropriate circumstances, the flange  13  can be provided with apertures  82  through which the conductors  81  may be accessed from the lower face of the flange  13 . 
       FIG. 15  illustrates a tee  10  on which a plurality of conductors  86  are printed or otherwise established on the upper side of the flange  13 . The conductors  86  are isolated from one another and are isolated from the flange by an insulating layer applied to the top surface of the flange  13 . Additionally, the conductors  86  are over-coated with an insulating layer to avoid short circuiting. The over-coating of the top insulating layer may be omitted at points  87  to facilitate connection with electrical contacts or electrical wires. 
     Making reference to  FIG. 16 , a conventional grid tee  10  can be fitted with a cap  91  after the grid tee is installed. The cap can be made of plastic or metal suitably coated with an insulating layer on its interior. The cap  91  is printed with a conductive ink to form one or more conductors. The conductors  92  are over-coated with an insulating material to prevent shorting against surfaces or edges of the tee  10 . Alternatively, the cap  91  can be structured such that when it is installed, the conductor or conductors are spaced away from the lower surface of the flange  13  or cap  16 . By temporarily removing the cap  91 , the conductors  92  are readily accessible for establishing a circuit with a connector for supplying or drawing power. 
       FIG. 17  illustrates a novel grid tee  96  which is extruded or otherwise formed of electrically insulating material such as PVC or other well-known thermoplastic or thermosetting material. Conductors  97  are attached to any of those surface locations as previously described and preferably on non-visible surfaces of the tee  96 . Since the tee  96  is electrically insulating, there is no requirement that the conductors be insulated from the tee and can be directly attached to the same by any suitable expedient such as adhesive or mechanical interlocking. 
     The foregoing tee constructions and electrification of the same can deliver power to various devices carried over, in or under the plane of a ceiling. Such devices while drawing power from the grid electrification, can communicate to other nearby or remote devices with radiofrequency signaling. 
     While the invention has been shown and described with respect to particular embodiments thereof, this is for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein shown and described will be apparent to those skilled in the art all within the intended spirit and scope of the invention. Accordingly, the patent is not to be limited in scope and effect to the specific embodiments herein shown and described nor in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.

Summary:
An elongated grid tee for supplying low voltage power on a suspended ceiling comprising at least two electrically conductive paths electrically insulated from each other, extending lengthwise of the tee, and accessible for receiving or supplying electrical power at numerous locations along the length of the tee.