Abstract:
A multiuse electric tile module for walling, flooring, or roofing applications having a photovoltaic cell, thermovoltaic cell, electroluminescent material, or a combination of these disposed over a rigid substrate, such as ceramic. Each tile is electrically connectable through a male-to-female connecter to at least one adjacent tile without external wiring. Preferably, a sealing layer is disposed over the electrical elements and rigid substrate to seal and protect each tile. Optionally, each tile may further include an inverter to convert direct current to alternating current or a battery to store electricity. The electroluminescent material provides light for architectural accents or nighttime visibility.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of Invention  
           [0002]    The invention generally relates to outdoor tiles for wall, roof and floor applications. More particularly, the invention relates to connectable tile modules that include electrical components, such as electroluminescent material, photovoltaic, or thermovoltaic cells.  
           [0003]    2. Description of the Related Art  
           [0004]    Providing electricity through photovoltaic and thermovoltaic cells is becoming more popular as these technologies have come down in cost and reliance on other sources of electric power is increasingly disfavored for environmental and strategic reasons. However, providing a general use tile with electrical components that is easy to install and electrically connectable to other tiles without external wiring has been elusive.  
           [0005]    The conversion of electromagnetic radiation from thermal sources to electricity is known as thermophotovoltaic (TPV) power generation. While the overall thermal-to-electric conversion (TEC) efficiency of TPV systems has typically been lower than hoped for, recent developments in materials and techniques have changed the situation dramatically. Several rare earth oxides, for example, have been shown to have altered spectral distributions in their emission spectra, leading to a more efficient TPV operation. For example, GaAs, GaSb, InGaAs are used in thermoelectric applications.  
           [0006]    Photovoltaics refer to cells that convert sunlight directly into electrical energy. The electricity is direct current and can be used that way, converted to alternating current through the use of an inverter, or stored for later use in a battery. Conceptually, in its simplest form, a photovoltaic device is a solar-powered battery whose only consumable is light. Because sunlight is universally available, photovoltaic devices have many advantages over traditional power sources. Photovoltaic systems are modular, and so their electrical power output can be engineered for virtually any application. Moreover, incremental power additions are easily accommodated in photovoltaic systems, unlike more conventional approaches such as fossil or nuclear fuel, which require multi-megawatt plants to be economically feasible.  
           [0007]    Although photovoltaic cells come in a variety of forms, the most common structure is a semiconductor material into which a large-area diode, or p-n junction, has been formed. In terms of basic function, electrical current is taken from the device through a contact structure on the front that allows the sunlight to enter the solar cell and a contact on the back that completes the circuit.  
           [0008]    The original and still the most common semi-conducting material used in PV cells is single crystal silicon. Single crystal silicon cells are generally the most efficient type of PV cells, converting up to 23% of incoming solar energy into electricity. These cells are also very durable and have proven their long life in many space related applications. The main problem with single crystal silicon cells is their production costs. Growing large crystals of silicon and then cutting them into thin (0.1-0.3 mm) wafers is slow and expensive. For this reason, researchers have developed several alternatives to single crystal silicon cells, with hopes of reducing manufacturing costs.  
           [0009]    Alternatives to single crystal silicon cells include poly-crystalline silicon cells, a variety of “thin film” PV cells, and concentrating collectors. Poly-crystalline silicon cells are less expensive to manufacture because they do not require the growth of large crystals. Unfortunately they are less efficient than single crystal cells (15-17%). “Thin films” (0.001-0.002 mm thick) of “amorphous” or uncrystallized silicon are another PV alternative. These thin films are inexpensive, and may be easily deposited on materials such as glass and metal, thus lending themselves to mass production. Amorphous silicon thin film PV cells are widely used in commercial electronics, powering watches and calculators. The problem with these cells is that they are not very efficient (12% in the lab, 7% for commercial cells), and they degrade with time, losing up to 50% of their efficiency with exposure to sunlight.  
           [0010]    Thin film PV cells made from other materials have also been developed in an attempt to overcome the inefficiency and degradation of amorphous silicon thin films, while retaining low production costs. Gallium arsenide (GaAs), copper indium diselenide (CuInSe 2 ), cadmium telluride (CdTe) and titanium dioxide (TiO 2 ) have all been used as thin film PV cells, with various efficiencies and production costs. Titanium dioxide thin films, just recently developed, are very interesting because they are transparent and can be used as windows.  
           [0011]    In terms of artistic and practical applications (e.g. improved nighttime visibility), electroluminescent materials have become popular novelties. Electroluminescent materials, such as phosphor, emit light when a current is passed through it. Commercially available phosphor-based electroluminescent materials use, for example, zinc sulphide doped with manganese (ZnS:Mn) as amber-glowing phosphor. Making different-color luminescing material for artistic effect is a matter of blending elements that will electroluminesce with red, green, blue (or a combination of these to make light of many different colors). For example, strontium sulphide doped with copper, denoted ‘SrS:Cu’ can be “tuned” by controlling the proportions of five-neighbored and six-neighbored copper by adding the elements sodium and yttrium to the material, tipping light emission toward the greens.  
           [0012]    While electroluminescent building tiles are not known to exist in the related art, several examples of photovoltaic cells used on roof coverings are. For example, U.S. Pat. No. 4,321,416 issued to Tennant discloses a photovoltaic module in the form of a shingle having a mounting portion and flat, flexible leads extending from each module for connection to other flexible leads or to a separately wired electrical network. Furthermore, a photovoltaic shingle system is disclosed in U.S. Pat. No. 5,437,735. These shingles are made up of a strip of roofing material with photovoltaic generating devices adhered thereto. While each strip is electrically interconnected, external leads are necessary to carry electricity away from each strip. Additionally, U.S. Pat. No. 4,860,509 by Laaly et al. describes a flexible roofing membrane with photovoltaic cells incorporated therein. A final example of a solar roof assembly is found in U.S. Pat. No. 5,316,592 issued to Dinwoodie. This patent discloses a three-element assembly in which photovoltaic cells are disposed upon an insulating element that is placed upon a roof membrane. However, as with the interconnected roofing shingles above that are applied in rolls or strips, cosmetic or structural damage to one area necessitates that the entire section, rather than an individual module, be replaced.  
           [0013]    While all of the building materials described above are suited for roof applications, none would be practical as flooring or for wall applications because of their external lead requirements, lack of rigidity, and/or unsuitable structural characteristics. Moreover, the bulkiness and expense of having separate photovoltaic regions and mounting regions can make some of these building materials economically unattractive and difficult to install. Furthermore, none of these inventions utilize a connectable rigid tile module with an electroluminescent material, a photo- and/or thermo-voltaic cell, or a combination of these, to produce electricity and/or lighting effects. Thus, there continues to be a need for a novel and improved multiuse and connectable tile modules that (1) utilize sunlight and heat to produce and store electricity and/or lighting effects, (2) are easy to install, (3) have no external wiring requirements to interconnect with each other, (4) feature decorative illumination options, and (5) are commercially feasible to produce.  
         SUMMARY OF THE INVENTION  
         [0014]    The invention meets the aforementioned need by providing a rigid, multi-use tile module that is electrically connectable to a surrounding tile through at least one male-to-female connector. In one preferred embodiment, the invention includes a combination of photovoltaic and thermovoltaic thin films disposed over a rigid substrate, such as ceramic, with each module being electrically connectable through a male-to-female connection along a side edge or a bottom tab to at least one adjacent module, thereby eliminating the need for a separately wired electrical network. In another preferred embodiment, the tile module of the invention includes an electroluminescent element to provide light for architectural accents or nighttime visibility. Moreover, each inventive module may further include an inverter to convert direct current to alternating current, a battery to store electricity, a sealing layer to protect the tile and its electrical components, and/or a reflective element.  
           [0015]    The individual tiles may be connected to each other in series to form an array by simply connecting the male prong to a female socket of an adjacent tile or vice versa. Parallel, or combinations of serial and parallel, arrangements of tile modules are also contemplated through, for example, connecting the end of every row to a bus bar or cable and using non-conductive “dummy” tiles in alternate rows.  
           [0016]    Definitions  
           [0017]    The term “thin film” means micron-sized material deposited as a element over another conducting or non-conducting material.  
           [0018]    The term “module” means a self-contained assembly of electronic components and circuitry.  
           [0019]    The term “tile” means a piece of rigid material of the type traditionally used on roofs, floors, or walls and includes both substantially flat tile pieces as well as tile pieces that are curved in cross-section.  
           [0020]    The term “thermovoltaic” is meant to encompass all known materials that convert heat into electricity, including thermoelectric material such as mercury cadmium telluride thermal diodes.  
           [0021]    An object of this invention is to provide a multi-use flooring, roofing, and walling tile module that contains at least one electrical component comprising an electroluminescent material, photovoltaic element, a thermovoltaic element, or combinations thereof.  
           [0022]    A second object of this invention is to provide a multi-use tile that is easy to install.  
           [0023]    A third object of this invention is to provide multi-use tiles that do not require external wiring to electrically connect with each other.  
           [0024]    A fourth object of the invention is to provide electrically connectable tiles that produce light for enhancement of nighttime visibility and/or decorative effect.  
           [0025]    A fifth object is to provide a photovoltaic and thermovoltaic tiles that are simple and economical to manufacture.  
           [0026]    The invention accomplishes these and other objects by providing a novel and improved tile module disposed with built-in electrical connectors and one or more electrical components.  
           [0027]    Various other purposes and advantages of the invention will become clear from its description in the specification that follows and from the novel features particularly pointed out in the appended claims. Therefore, to the accomplishment of the objectives described above, this invention consists of the features hereinafter illustrated in the drawings, fully described in the detailed description of the preferred embodiments, and particularly pointed out in the claims. However, such drawings and description disclose only some of the various ways in which the invention may be practiced.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    [0028]FIG. 1 schematically depicts a side view of an embodiment of the invention in cross-section.  
         [0029]    [0029]FIG. 2A schematically depicts a side view of a preferred embodiment of the invention.  
         [0030]    [0030]FIG. 2B schematically shows a bottom view of the embodiment of FIG. 2A.  
         [0031]    [0031]FIG. 3A schematically depicts a top view of a floor or wall application of the tile shown in FIG. 1.  
         [0032]    [0032]FIG. 3B schematically depicts a side view of four of the tiles shown in FIG. 3A.  
         [0033]    [0033]FIG. 4 schematically depicts a side view of a shingle-like roof application of the invention.  
         [0034]    [0034]FIG. 5A schematically depicts a front view of a curved tile roof application of the invention.  
         [0035]    [0035]FIG. 5B schematically depicts in side view of embodiment shown in FIG. 5A.  
         [0036]    [0036]FIGS. 6A and 6B schematically depict a single roof tile of FIG. 5A from a bottom view and in cross-section, respectively.  
         [0037]    [0037]FIG. 7 schematically depicts a basic embodiment of the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0038]    The invention, in general, provides a multipurpose, electrically connectable tile module that contains an electroluminescent, photovoltaic, and/or thermovoltaic element upon its upper side. Preferably, the electroluminescent and voltaic elements are electrically insulated and are sealed to the tile substrate by a glaze. Optionally, the tile module may also include a battery and/or inverter. The tile modules are electrically connected by “male-to-female” (e.g., prong and socket) connectors along a side edge or bottom tab to eliminate the need for external wiring between tiles. Accordingly, the tile modules can be used to provide interesting light effects and/or electricity in a variety of outdoor flooring, roofing, and wall facade applications.  
         [0039]    Turning to an especially preferred embodiment in FIG. 1, the electric tile  10  includes a rigid substrate  12 . Preferably, the rigid substrate  12  includes ceramic or cement. However, tiles may be made from other rigid materials, including, but not limited to, clay, mud, polymers such as a plastic, polymer/clay or polymer/ceramic hybrids, or glass. Whatever material is chosen, the rigid substrate  12  must be composed of an electrically insulating material to prevent short circuits among connected tiles modules. Rigid substrate  12  includes a top side  14 , a bottom side  16 , and side edges  18 . Although a substantially rectangular shape for the rigid substrate is shown, it should be understood that the tile modules may assume any shape having top and bottom sides and one (e.g., circles) or more side edges (e.g., triangles, squares, hexagons).  
         [0040]    Disposed over top side  14  are thermovoltaic element  20  and photovoltaic element  22 . Elements  20  and  22  preferably comprise thin film thermovoltaic and photovoltaic cells because thin films are inexpensive and may be easily deposited on many different rigid materials by several different methods well known in the art. For example vacuum deposition, ion sputtering, and spin-coating methods may be used.  
         [0041]    Preferably, elements  20  and  22  are coated with a transparent, electrically insulating material  24 , such as silicon. Also preferably, the tile  10  is coated with a sealing layer  26 . The sealing layer is designed to make the tile modules wear and weather resistant and may include, but is not limited to, fired ceramic glazes, liquid glazes, sol gels, polymer or glass-based coatings, thick films, or a combination of these. To enhance the efficiency of the thermovoltaic element  20 , a heat-reflective element  28  may be disposed on the top side  14  and underneath thermovoltaic element  20 . Optionally, the sealing layer  26  may include a light-enhancing product, such as micro industrial diamonds (not shown).  
         [0042]    Obviously, many variations exist on the type and placement of the electrical wiring and other electrical components of each tile module. One of these many possible electrical connection arrangements is shown schematically in FIG. 1. Circuit  30 , which has a negative polarity, and circuit  31 , which has a positive polarity, both contain diodes  32  to prevent backflow of electricity in the event of a voltage differential between elements  20  and  22 . Hence, the electricity produced from the voltaic elements flows along two separate wires  34  (connected to circuit  30 ) and  36  (connected to circuit  31 ). The wires  34  and  36  may be run through channels (not clearly shown, see FIG. 6A) in rigid substrate  12  or sealed to bottom side  16 . Wires  34  and  36  then terminate at one end in a male connector  38  and at the other female connector  40 . As shown, connectors  38  and  40  are disposed along opposing side edges  18 . However, a corner tile module would have connectors extending from perpendicular side edges. This configuration is especially suited for wall and floor applications of the tile modules  10  because it allows the tiles to interconnect without the need for complex wiring or installation problems due to placement of wires in mortar or grout.  
         [0043]    Turning to FIG. 2A, a second embodiment of the invention featuring an electroluminescent element is shown. Tile module  44  includes a rigid substrate  46  with a top side  48 , bottom side  50 , and opposing side edges  52 . Disposed over top side  48  are thermovoltaic element  54 , photovoltaic element  56 , and electroluminescent element  58 . As discussed above, the electroluminescent element is composed of an electroluminescent material, such as phosphor material, that emits light when a current is passed through it. Optionally, a reflective element  60  is disposed between the thermovoltaic element  54  and the top side  48 .  
         [0044]    Elements  54 ,  56  and  58  are separated by a transparent, electrically insulating material (e.g. silicon), which may also act as a sealing layer. In terms of electrical connections, one of many possible arrangements is represented by circuits  64  and  66 . Circuit  64  has a negative polarity, while circuit  66  has a positive polarity, with both circuits containing diodes  68  to prevent backflow of electricity in the event of a voltage differential between elements  54 ,  56 , and  58 . The electricity produced from the voltaic elements flows to two separate wires  74  and  76  (shown in phantom line). Wires  74  and  76  lead to a male connector  78  and a female connector  80 . As shown, connectors  78  and  80  protrude from opposing side edges  52 . Also, the flow of electricity to the electroluminescent element  58  is controlled by switch  84  in this case.  
         [0045]    [0045]FIG. 2B shows a bottom view of the tile module of FIG. 2A. Thus, the fact that the male connector  78  is made up of two prongs in this case can be seen more clearly.  
         [0046]    A simple floor or wall facade application of the invention is shown in FIGS. 3A (top view) and  3 B (side view). Tile modules  86  are connected along a side edge  88  via male connector  90  to female connector  92 . Thus, a flow of electricity  94  is established between tiles.  
         [0047]    A simplified roofing application of the invention is shown in FIG. 4. Tile modules  98  are made so that a bottom tab  100  houses a connector  102  (in this case a female connector) such that frictional engagement of a male connector  104  can be made along a side edge  106  of an adjoining tile. Holes  108  allow each tile  98  to be attached by a nail or screw to a roof substructure  110 , if desired. The apex of the pictured roof is preferably covered with a cap piece  112 . The exposed connectors  102  and  104  can then be connected by wires  114  to a battery and/or main electrical service.  
         [0048]    [0048]FIGS. 5A and 5B illustrate in front and side view a roof application of the invention using a tile module that is curved in cross-section. The roof  118  includes tile modules  120 , which are interconnected by a male connector  122  coupled to a female connector  124 . Each tile may include a hole  126  to facilitate attachment to the roof substructure (not shown). Wires  127  then transmit electricity to a battery or main service through end wires  128 .  
         [0049]    [0049]FIGS. 6A and 6B illustrate in a front and side cross-sectional view, respectively, one of the curved roof tile module shown in FIGS. 5A and 5B. Tile  120  has a photovoltaic element  130  disposed over the top of rigid substrate  132 . On the bottom of rigid substrate  132 , a tab  134  houses channel  136  and wires  137  and  138 . Male connector  140  is disposed at side edge  141  while female connector  142  is located within tab  134 .  
         [0050]    [0050]FIG. 7 shows a simple embodiment of the multi-use tile module in side cross-section. Tile  145  is made up of rigid substrate  147 , having a top side  148 . Disposed over top side  148  is electroluminescent element  149 . Electrically insulating element  150  and sealing layer  151  coat the electroluminescent element and rigid substrate as described in previous embodiments. Element  151  receives electricity from negative and positive leads  152  and  153 , which are connected to wires  154  and  155 , respectively. Connectors  157  and  158  allow tile  145  to receive current from an adjoining tile. Of course, designs, letters, or shapes may be made with the electroluminescent element to add a creative element to the tile  145 .  
         [0051]    It should be noted that the manufacture of the invention may be accomplished by those skilled in the art in several different way. For example, rigid substrate material can be cast or molded and then cured or fired. Circuitry and connecting material is then applied at different points as one or more electric component elements (photovoltaic, thermovoltaic, and/or electroluminescent) are deposed over the rigid substrate. If thin films are used, these films can be deposited on a reflector material (most likely stainless steel) and then laminated to the substrate, or a thin film can be deposited directly on the substrate. At this point, the various sealing coatings or glazes would be applied to the tile, which could then be cured or fired as necessary. Other electric components, such as a battery, inverter, or connecters, would then be installed to complete the tile.  
         [0052]    As would be understood by those skilled in the art, any number of functional equivalents may exist in lieu of the preferred embodiments described above. Thus, as will be apparent to those skilled in the art, changes in the details and materials that have been described may be within the principles and scope of the invention illustrated herein and defined in the appended claims.  
         [0053]    Accordingly, while the present invention has been shown and described in what is believed to be the most practical and preferred embodiments, it is recognized that departures can be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent products.