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CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of U.S. patent application Ser. No. 11/137,705 now U.S. Pat. No. 7,610,731, file May 25, 2005 which is a continuation-in-part of U.S. patent application Ser. No. 11/032,196 filed on Jan. 10, 2005 and converted to a U.S. Provisional Application Ser. No. 60/651,490 on May 20, 2005 and having a filing date of Jan. 10, 2005. Priority is claimed from all the above applications. 

   FIELD OF THE INVENTION 
   The present invention relates to floor coverings and methods of use thereof. 
   BACKGROUND OF THE INVENTION 
   Applying new flooring may provide enhanced aesthetic appeal or fulfill a functional purpose. Generally, applying flooring requires the use of staples, nails or an adhesive to adhere the flooring material to the sub-floor. Depending on the combination of sub-floor type, new flooring installed and the particular adhesive used, applying new flooring may damage the sub-floor through scuffing, gauging, nail holes or chemical damage. For example, with marble floors, a conventional installation damages the sub-floor from the tar paper, wire mesh, mortar bed, adhesive and grout used to lay the marble, and the damage is compounded by the weight of the marble and use of the floor. This may be undesirable and require extensive restoration efforts if the sub-floor is hardwood. 
   Furthermore, certain flooring materials may be expensive and the addition of labor expenses may make a new floor unattainable for price-conscious consumers. While a do-it-yourself application may reduce the costs, some consumers may be apprehensive to use particular adhesives or grout which may require planning for timing, ventilation and settling. For example, using a cement backer board, which is designed to be easier than the conventional installation described above, requires that a cement board be attached to a plywood sub-floor using adhesives and screws, then bonding the tile to the backer board using a thin set adhesive placed over a fiberglass reinforcing mesh. 
   It may be desirable to provide a “floating” floor structure which provides the appearance of a permanent flooring structure at a reduced cost but without the use of damaging permanent attachment means to secure the structure to the floor. It may be desirable that the installation is primarily mechanical, not requiring the use of chemical adhesives. It may also be desirable to provide a floor structure that is stable and does not substantially shift upon using the floor. 
   SUMMARY OF THE INVENTION 
   The present invention provides a floor structure unit, comprising: a tray, a flooring material, a rubber grommet, and a rubber matrix. The tray includes an upper horizontal surface, a lower horizontal surface, at least one retaining wall extending vertically from either of the horizontal surfaces, a first set of interlocking members, and a second set of interlocking members, where the first set of interlocking members and the second set of interlocking members are contrapositive. The flooring material is disposed on the tray upper horizontal surface such that the first set of interlocking members is substantially flush with the flooring material and the second set of interlocking members extends beyond the flooring material. The rubber matrix is disposed in the tray lower horizontal surface, and the rubber grommet is disposed about the perimeter of the at least one retaining wall. The rubber grommet and the rubber matrix are a unitary piece. 
   The present invention also provides a method of making a floor structure unit, comprising providing tray having interlocking members disposed thereon; placing a rubber grommet around the perimeter of the tray; attaching a rubber matrix onto a lower horizontal surface of the tray; and securing a flooring material to an upper horizontal surface of the tray. 
   The present invention also provides a method of placing a floor structure, comprising: interlocking contrapositive members of at least two floor structure units. The floor structure units comprise: a tray, a flooring material, a rubber grommet, and a rubber matrix. The tray includes an upper horizontal surface, a lower horizontal surface, at least one retaining wall extending vertically from either of the horizontal surfaces, a first set of interlocking members, and a second set of interlocking members, where the first set of interlocking members and the second set of interlocking members are contrapositive. The flooring material is disposed on the tray upper horizontal surface such that the first set of interlocking members is substantially flush with the flooring material and the second set of interlocking members extends beyond the flooring material. The rubber matrix is disposed in the tray lower horizontal surface, and the rubber grommet is disposed about the perimeter of the at least one retaining wall. The rubber grommet and the rubber matrix are a unitary piece. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  depicts a perspective view of a floor structure unit according to embodiments of the present invention; 
       FIG. 2  depicts a top view of a tray according to embodiments of the present invention; 
       FIG. 3  depicts a perspective view of a tray and retaining walls according to embodiments of the present invention; 
       FIG. 4  depicts a bottom view of a tray, rubber grommet, and rubber matrix according to embodiments of the present invention; 
       FIG. 5  depicts a perspective view of a tray and rubber grommet according to embodiments of the present invention. 
       FIG. 6  depicts a side view of a floor structure unit according to embodiments of the present invention; 
       FIG. 7   a  depicts a side view of a floor structure unit according to embodiments of the present invention; 
       FIGS. 7   b - c  depict exploded corner views of the side view of  FIG. 7   a ; and 
       FIG. 8  depicts a side view of a tray, stone and rubber grommet according to embodiments of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     FIGS. 1-4  depict a floor structure unit  10  comprising a tray  12 , having a first set  14  of interlocking members  16 , a second set  18  of interlocking members  16 , a rubber matrix  20 , a flooring material  22 , and a rubber grommet  24 . The tray  12 , the rubber matrix  20 , the flooring material  22  and the rubber grommet  24  of the floor structure unit  10  are attached using an adhesive or glue. 
   As depicted in  FIG. 3 , the tray  12  is a square and comprises an upper horizontal surface  26  and a lower horizontal surface  28 . It is understood that the tray  12  may be of any appropriate shape (polygon, circular, freeform, etc.) and a square is depicted and discussed herein for illustrative purposes only and that one skilled in the art appreciates and understands slight modifications to accommodate various shapes. The upper horizontal surface  26  is the substrate for the flooring material  22  as discussed later herein. 
   The lower horizontal surface  28  includes the substrate for the sets of interlocking members  14  and  18  and serves as the substrate for attachment of the rubber matrix  20  and interconnected rubber grommet  24 . Each tray  12  interlocking member  16  comprises a notch  30  and a recessed segment  32 . The notch  30  is generally a protrusion of a greater thickness than the recessed segment  32 . The protrusion may be rounded, squared or an irregular shape. The notch  30  connects with the recessed segment  32  of an adjacent floor structure unit  10  for a secure fit. Generally, the notch  30  of a first interlocking member  16  connects with the recessed portion  32  of a second interlocking member  16 . In various embodiments, it may be desirable to have complimentary shaped notches  30  and recessed segments  32 . For example, a rounded notch  30  mating with a rounded hollowed recessed segment  32  may provide a secure fit thereby preventing slippage of the floor structure. 
   The sets  14  and  18  of interlocking members  16  may be arranged such that all of the notches  30  face towards either the upper horizontal surface  26  or lower horizontal surface  28  of the tray  12 , as depicted in  FIGS. 2 and 4 . Preferably, each interlocking member  16  of the sets  14  and  18  alternate where one notch  30  faces towards the upper horizontal surface  26  and then the adjacent notch  30  faces towards the lower horizontal surface  28 , as depicted in  FIGS. 1 ,  3 , and  5 . In a preferred embodiment, the notches  30  and recessed segments  32  are arranged such that the first set  14  and the second set  18  of interlocking members  16  are contrapositive. This contrapositive arrangement provides the lock fit and structural integrity of the flooring system. 
   The lower horizontal surface  26  may also comprise a grid  34 . The grid  34  may be produced when the tray  12  is injection molded. The grid  34  may include any geometric or curved pattern or a random pattern to provide greater surface area for the rubber matrix  20  and in various embodiments, an optional adhesive  36 . 
   Referring to  FIG. 5 , the tray  12  may also include retaining or side walls  40 . These walls  40  may be used to hold the flooring material  22  in a fixed position, provide strength, and prevent debris from reaching the sub-floor. Preferably, the retaining walls  40  upwardly extend from two adjacent sides of the tray  12 . The retaining walls  40  provide enhanced support to components of the flooring unit  10 . The walls  40  support the rubber grommet  24  on the tray  12 , as further detailed later herein, and are used as a projection point for interlocking members  16 , as depicted in  FIGS. 7   a - c  and  FIG. 8 . 
   Referring to  FIG. 6 , the flooring material  22  is disposed on the upper horizontal surface  26  of the tray  12 . Flooring materials  22  may include traditional materials  22  such as stone, wood, ceramic, textile, paper, plastic materials  22 , and mixtures thereof. Stone materials preferably include slate, limestone, flagstone, granite, marble, or aggregates thereof. Depending on the flooring material  22  selected, the tray  12  shape and dimensions may be adapted for proper structural integrity and aesthetic appeal. The flooring material  22  may be a solid color, pattern, or contain a grain or texture. The flooring material  22  may be a solid or contain a decoration, for example, a marble unit having glass covered cut away which houses a contrasting color wood. Various combinations of flooring materials  22  provide endless options for function and decoration. 
   Returning to  FIG. 4 , the rubber matrix  20  provides a contact surface for the sub-floor  38 . The term “matrix” is used to represent a series of interconnected points and does not imply any particular geometry. As depicted, the rubber matrix  20  is a collection of intersecting lines forming a plurality of right angled structures. It is understood that the rubber matrix  20  may include any geometric or curved pattern or random pattern to provide a surface area for contact with the sub-floor  38 . The rubber matrix  20  may be of consistent dimensions or it may include regions  42  having an increased thickness or width. As depicted, the rubber matrix  20  includes a plurality of circular regions  42  at select line intersections. These regions  42  may be of any appropriate diameter or cross section depending on the particular shape selected. The regions  42  may include polygonal, circular or freeform shapes. The regions  42  may match in shape or may be a plurality of shape combinations and sizes. Additionally, the regions  42  may include depressed or raised sub-regions  44 . These sub-regions  44  may provide supplemental protection for the sub-floor  38 , allow for expansion or reduction of the selected materials  22  due to changes in temperature and provide structural support for the floor structure unit  10 . In various embodiments, the sub-regions  44  may be used as an alignment guide for a user. For example, in an embodiment combining circular and hexagonal regions  42 , the user may be instructed to align the components so that the hexagons are aligned with hexagons and the circles aligned with other circles. This may be particularly useful when applying a floor structure unit  10  of different colors or creating a pattern (such as a multi-level diamond, herringbone or zigzag) in the finished floor using a collection of floor structure units  10 . 
   The rubber matrix  20  may be made of any suitable rubber, including but not limited to natural rubber, cis-polyisoprene, polybutadiene, poly(styrene-butadiene), styrene-isoprene copolymers, isoprene-butadiene copolymers, styrene-isoprene-butadiene tripolymers, polychloroprene, chloro-isobutene-isoprene, nitrile-chloroprene, styrene-chloroprene, and poly (acrylonitrile-butadiene). Additives such as coloring agents, strength enhancing agents, or friction modifying agents may be added to the rubber. 
   Referring to  FIGS. 7   a - c  and  8 , the rubber grommet  24  is disposed about the perimeter of at least one retaining wall  40  of the tray  12 . The rubber grommet  24  advantageously provides support and impact cushioning in the lateral and longitudinal directions with respect to the tray  12 . This is particularly useful to prevent damaging of fragile flooring materials  22  when they are joined together. The grommet  24  resembles grout and grout joints because when the floor structure is assembled, the rubber grommet  24  engages a region of the flooring material  22  on an adjacent tile. Preferably, the rubber grommet  24  is sufficiently resilient to maintain its shape when a bare region of flooring material  22  is placed against the rubber grommet  24 , as detailed later herein. 
   As best depicted in  FIGS. 4 and 7   c , the rubber grommet  24  and the rubber matrix  20  are a unitary piece. The region of the rubber grommet  24  surrounding the perimeter of the retaining walls  40  along the tray lower surface  28  forms an outer edge of the rubber matrix  20 . The monolithic matrix  20  and grommet  24  unexpectedly provides enhanced cushioning, absorption of footfall impact and noise, and eliminates shifting of the new floor because energy transfer is limited to between the rubber matrix  20  and rubber grommet  24  instead of to the floor structure unit  10  and flooring material  22 . Furthermore, the monolithic structure eliminates debris from reaching the sub-floor  28 . If any debris invades the flooring unit  10 , the debris is trapped between the region of the rubber grommet  24  surrounding the perimeter of the retaining walls  40  that forms the outer edge of the rubber matrix. 
   The rubber grommet  24  color may be of the same or different color(s) as the flooring material  22  or it may be an accent color entrained in a multi-colored flooring material  22  such as marble. The rubber grommet  24  may be made of the same rubber materials used for the rubber matrix  20 . 
   Between the voids in the rubber matrix  20 , an adhesive  36  may be applied. Suitable adhesives  36  include thermoplastic adhesives, thermosetting adhesives and rubber-resin blends. Specific examples of adhesives  36  include acrylic resin adhesive, cyanoacrylate adhesives, epoxy adhesives, phenolic adhesives, polyurethane adhesives, adhesives incorporating a dispersed, physically separated but chemically attached rubber phase, and mixtures thereof. Preferably, the adhesive  36  is a methacrylate-based adhesive. For example, a preferable adhesive  36  may comprise dodecyl methacrylate, hexadecyl methacrylate, poly(butadiene, methylmethacrylate and styrene), chlorosulfonated polyethylene, methacrylic acid and a methyl methacrylate monomer. Various factors including the particular flooring material  22  selected, the surface area covered by the rubber matrix  20  and the textured grid  34  of the tray  12  may be incorporated in the selection of the adhesive  36 . 
   The floor structure unit  10  is made by first providing a tray  12  having interlocking members  16  disposed thereon. The tray  12  may be made using injection molding. The details of the tray  12  including the textured grid  34 , interlocking members  16 , notches  30  and recessed segments  32 , may be constructed during a single injection molding step or a combination of steps such as an injection molding followed by pressing a form onto the tray  12 . 
   Placing the rubber grommet  24  and placing the rubber matrix  20  may be performed as distinct steps or a single step. In a preferred embodiment, the rubber matrix  20  is applied using double injection molding techniques and where the tray  12  materials and the rubber materials are injected into the same mold to form a single part. Double injection molding is preferred because the process may be designed to reduce assembly labor and may prevent defects in the flooring unit from improper orientation that may affect individual parts. 
   To place the new floor structure, the notches  30  on a first floor structure unit  10  are aligned with the contrapositive notches  30  or a second floor structure unit  10 . The notches  30  and recessed segments  32  may be engaged by pushing or snapping the units together. Manual pressure or a tool such as a hammer or mallet may be used to engage the interlocking members  16 . Preferably, the flooring units  10  are aligned such that the retaining walls  40  of one flooring unit  10 , engage bare flooring materials  22  of adjacent flooring units  10 . The process is repeated until the desired pattern or “floating” floor size is achieved. As stated above, the rubber grommet  24  is sufficiently resilient such that when the floor units  10  are engaged, the rubber grommet  24  serves as a cushion between edges of bare flooring material  22 . Preferably, the rubber grommet  24  is able to withstand the accumulation of pressure resultant from laying a plurality of flooring units  10  in various directions and combinations. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

Summary:
A floor structure unit, comprising: a tray, a flooring material, a rubber grommet, and a rubber matrix is provided. The tray includes an upper and lower horizontal surface, at least one retaining wall, a first and a second set of contrapositive interlocking members. The flooring material is disposed on the tray upper horizontal surface such that the first set of interlocking members is substantially flush with the flooring material and the second set of interlocking members extends beyond the flooring material. The rubber matrix is disposed in the tray lower horizontal surface, and the rubber grommet is disposed about the perimeter of the at least one retaining wall. The rubber grommet and the rubber matrix are a unitary piece. Methods of manufacture and use thereof are also provided.