Flexible electrically heated tiles made from crumb rubber

A flexible, heated, non-allergenic mat particularly adapted for use with animals has a flexible layer of recycled crumb rubber formed under heat and pressure with resin. A reflective sheet is disposed in the flexible layer for reflecting heat. A wire forming a heating element is disposed in the flexible layer above the reflective sheet for heating the mat in response to an applied electric current. A plug and socket may be formed in an edge of the flexible layer so that adjacent mats may be electrically coupled to form a larger heated surface.

BACKGROUND
 1. The Field of the Invention.
 This invention relates to a products fabricated from crumb rubber. More
 particularly, the present invention is directed to a flexible tile made of
 crumb rubber with a heating element disposed therein configured for use as
 a heated non-allergenic animal mat, the tile also being modular and having
 a side configured for mating with an adjacent tile and an electrical
 coupling therebetween.
 2. The Background Art
 Domesticated animals, such as dogs and cats, are kept for many reasons
 including work, show, and pets. These animals can be valuable and play an
 important role in society. Working animals, such as guard dogs, perform
 valuable services. Show animals have prized characteristics. Pets often
 treated as a member of the family.
 Many of these animals, however, are kept outdoors because of the problems
 they pose indoors. For example, keeping a pet in the house can result in
 hair and odor being deposited on clothes, furniture, and carpet;
 scratching of furniture, walls and doors; and chewing of clothing,
 furniture and other items.
 Keeping these animals outdoors, however, can pose other problems,
 especially in areas with moderate or cold climates. Keeping a pet outdoors
 in inclement weather can be uncomfortable or even dangerous for an animal.
 The loss of a family pet can be akin to losing a family member. The loss
 of a working or show animal can also be a severe financial loss. While
 some animals have characteristics that enable them to survive outdoors,
 others do not.
 Various solutions have been proposed to solve the problems associated with
 keeping animals outdoors. For example, small, animal-sized doors have been
 installed in doors and walls to permit the animal to come indoors during
 inclement weather. One problem with these small doors is that they allow
 animals inside at any time, along with the associated problems. In
 addition, these small doors can be large enough to allow human intruders
 access to the home, or permit small children to wander out of the house.
 Another proposed solution has been the use of small, animal-sized houses,
 such as those commonly known as dog houses. Although these small houses do
 protect animals from rain and wind, they do little to protect the animal
 from the ambient cold.
 Another proposed solution is to leave the garage door ajar, thus allowing
 the animal access to the garage. However, leaving the garage door ajar has
 the same disadvantages inherent with dog houses, in that the garage is
 still typically cold and a garage door left ajar also invites human
 intruders.
 Another solution is to put a heating pad in the outside environment to
 provide heat for the animal. One problem with this solution is that
 heating pads are not configured for use in the outside environment or with
 animals. A heating pad left outdoors may become soiled, wet, malodorous,
 and harbor harmful microorganisms. In addition, a heating pad is not
 suited to resist an animals clawing or chewing. Thus exposing the animal
 to the risk of electrocution. Furthermore, conventional the heating pads
 are not configured to repel moisture encountered in the outside
 environment. Therefore, if they become wet, they can become an electrical
 hazard.
 Because of these problems, animals are often left outside to fend for
 themselves against the elements. The animals will often find various means
 of shelter, for example, under cars where the engine provides warmth.
 These various shelters may be hazardous to the animal. For example, an
 animal taking shelter under the car, can get run over or get oil or
 chemicals on its coat or such hazardous that may also be ingested by the
 animal.
 Another solution is to provide a bed for the animal, which usually
 comprises a blanket, pillow, or special doughnut-shaped bed. The problem
 with these beds is that the fabric may become wet and thus unattractive to
 the animal. In addition, the bed may lose its appeal to the animal.
 In view of the foregoing, it will become apparent that a heating pad
 specifically adapted for use in an outdoor environment will be a
 significant advancement in the art. It would also be a significant
 advancement in the art to provide a site of warmth which will deter the
 roaming of an animal which might otherwise find dangerous, undesirable
 shelters.
 Directly and indirectly heated flooring is known. However, these surfaces
 are commonly made of materials which may cause allergic or other reactions
 in animals. For example, dogs or cats may have an allergic reaction
 resulting in dermatologic conditions and respiratory ailments ranging from
 mild to severe.
 U.S. Pat. No. 4,878,332, issued Nov. 7, 1989, to Drake discloses a method
 for installing an electrical heating cable embedded in a layer of gypsum
 and cement based floor underlayment.
 U.S. Pat. No. 4,922,084, issued May 1, 1990, to Hutter discloses an
 apparatus for heating floors comprising rectangular blocks with heating
 coils mounted on the blocks' surfaces. The blocks are made of a
 heat-insulating material, so that heat released through the coils travels
 in one direction. The blocks may be made of TEFLON, silicone, hard foam,
 or synthetic rubber. U.S. Pat. No. 4,967,057 issued Oct. 30, 1990, to
 Bayless et al., discloses a flexible heating mat for preventing the
 accumulation of snow and ice on a walkway. The mat, which may be rubber,
 has a flat flexible mat casing with upper and lower surfaces and a heating
 strip within the casing.
 U.S. Pat. No. 4,990,744, issued Feb. 5, 1991, to Willner discloses an
 apparatus for heating floors. It has a thin heat-conducting substrate and
 a resistant heating wire positioned within the substrate. The substrate
 may be a bicomponent polymer such as nylon or PVC.
 U.S. Pat. No. 5,003,157, issued Mar. 26, 1991, to Hargrove discloses an
 apparatus with a ribbed mat made from a resilient polymeric material.
 U.S. Pat. No. 5,032,428, issued Jun. 11, 1991, to Hegstad discloses a
 surface coating or composite layer for heating floor surfaces. The surface
 coating has a foundation layer of plastic material, a heating cable placed
 on the foundation layer, another layer of plastic material covering the
 heating cable, and thermally-conducting particles embedded therein, and a
 covering layer.
 U.S. Pat. No. 5,291,000, issued Mar. 1, 1994, to Hornberg discloses a snow
 melting heater mat with a rigid or cellular mat containing electrically
 resistant heating cables connected together using flexible connectors.
 U.S. Pat. No. 5,380,988, issued Jan. 10, 1995, to Duyer discloses a heat
 mat structure for melting ice and snow. It has a plurality of thin, flat
 mats, with a laminate structure. Each mat has a substantially rigid back,
 an electrically resistant heating element which is surrounded by plastic
 layers and a semirigid upper surface layer.
 U.S. Pat. No. 5,461,213, issued Oct. 24, 1995, to Rodin discloses a heated
 floor having a sublayer which is laid on an existing floor, a series of
 heating cables laid on the sublayer, and separated by sheet material, such
 as gypsum, polyurethane, plastic, or particle board, and a surface layer.
 U.S. Pat. No. 5,591,365, issued Jan. 7, 1997, to Shields discloses an open
 lattice snow melting apparatus with a flexible heating mat having an open
 lattice arrangement. An electrical heating element is arranged in the mat.
 The mat may be vulcanized plastic such as polyethylene, polypropylene, or
 other similar polymeric material.
 U.S. Pat. No. 5,614,292, issued Mar. 27, 1997, to Saylor discloses a
 thermal walkway covering having an insulated bottom layer, a metal layer
 composed of carbonized electrically conducted rubber, and a top layer made
 of UV-resistant rubber or plastic.
 As indicated above, one of the problems with these devices is the materials
 with which they are made. Such materials can cause allergic reactions in
 animals. Thus, when making products for use with animals, it is important
 to use materials which are nonallergenic. In addition, it is also
 important to use materials which are inexpensive and recyclable. With the
 amount of plastic currently being generated, and plastic's resistance to
 biodegradation, it is important to use recycled materials.
 Another disadvantage with a number of the schemes taught by the
 above-mentioned patents is that they can not be easily configured for the
 desired size. Animals come in many different sizes, and thus their
 differing sizes needs to be accommodated. For example, a small dog, such
 as a Chihuahua, has different requirements than a Great Dane. Too small a
 surface area will not satisfy a large animal, while heating too large a
 surface area will be inefficient and wasteful of energy.
 Therefore, it would be advantageous to develop a heated mat, pad or tile
 for use with animals, such as house pets. It would also be advantageous to
 develop such a mat made of inexpensive, non-allergenic, recycled material.
 It would be advantageous to develop such a mat capable of being easily
 coupled with other mats to form a larger heated mat.
 OBJECTS AND SUMMARY OF THE INVENTION
 It is therefore an object of the present invention to provide a heated mat
 particularly adapted for use with, and by, animals.
 It is another object of the present invention to provide such a heated mat
 made of inexpensive, nonallergenic, recycled material.
 It is another object of the present invention to provide such a heated mat
 which can be physically and electrically coupled with other mats to form a
 larger heated surface.
 The above objects and others not specifically recited are realized in a
 specific illustrative embodiment of a heated mat, pad or tile made from
 recycled crumb rubber. The heated mat has a layer of flexible material,
 such as crumb rubber. The layer may be formed by heating recycled crumb
 rubber and resin under pressure. A heating element is disposed in the
 flexible layer. The heating element has a wire formed in a desired
 configuration secured to a layer of mesh material. The mesh material helps
 maintain the configuration of the wire and helps keep the flexible layer
 together. The wire has a first end extending out of the flexible layer for
 coupling with an electrical source for applying an electrical field
 through the wire and causing it to heat. A reflective sheet is disposed in
 the layer of flexible material for reflecting heat upwardly. A thermostat
 is disposed in the flexible layer and electrically coupled to the wire for
 sensing the temperature of the flexible layer and controlling the applied
 electric field to the wire.
 The mat may be made by providing a mold of desired size and shape. A first
 layer of recycled crumb rubber with resin is placed into the mold. A sheet
 of reflective material is disposed over the first layer of crumb rubber. A
 wire is placed over the reflective material in a desired configuration. A
 second layer of recycled crumb rubber is disposed over the wire,
 reflective material, and first layer. The layers of recycled crumb rubber
 are heated under pressure to produce one preferred embodiment of the
 present invention in accordance with one preferred method of the present
 invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Reference will now be made to the drawings wherein like structures will be
 provided with like reference designations.
 Referring now to FIGS. 1-4, a heated mat, pad or tile, generally indicated
 at 10, for providing a heated surface is shown. The heated mat 10 is
 configured for being disposed on an underlying surface, such as for
 example, earth, grass, wood, ground, asphalt, concrete, etc. In addition,
 the heated mat 10 is particularly configured for providing heat to
 animals, such as household pets. It is of course understood that the
 heated mat 10 of the present invention may also be configured and/or used
 for other purposes. For example, the heated mat 10 can be used to allow a
 human to stand upon or for providing heating anywhere a structure such
 heated mat 10 is suitable.
 Referring to FIG. 4, the heated mat or pad 10 preferably includes a
 flexible layer of material 14. The flexible layer 14 preferably has a
 first flexible layer 18 which is adapted for being disposed on the ground
 or other underlying surface, and a second layer 22 disposed on or over the
 first layer 18. The flexible layer of material 14 is preferably formed of
 recycled crumb rubber as described in further detail below.
 The flexible layer 14, or the first layer 18, has a lower surface 26
 configured for being disposed on the ground or other surface. The lower
 surface 26 may be formed with protrusions 34 and or indentations 36 to
 resist displacement of the mat 10 with respect to the ground. The flexible
 layer 14, or the second layer 22, has an upper surface 38. The upper
 surface 38 preferably has one or more of a variety of embossed designs
 formed directly in the surface 38 or second layer 22, for example as
 represented in FIG. 1. The designs may include various protrusions or
 indentations to provide a non-slip texture and/or esthetic patterns.
 A layer of reflective material or a reflective sheet 42 is disposed in the
 flexible layer 14, or over the first layer 18. The reflective sheet 42
 reflects heat. The reflective sheet 42 preferably covers a substantial
 area of the mat 10, or first layer 18, except for a portion 44 adjacent to
 a perimeter 45 the mat 10, as shown best in FIG. 3.
 A heating element 46 is disposed in the flexible layer 14, or over the
 first layer 18 and the reflective sheet 42. A mesh material or layer of
 mesh 50 is disposed over the reflective sheet 42. It is preferred that the
 mesh 50 be positioned between the heating element 46 and the reflective
 sheet 42, but other arrangements can also be used. The mesh 50 may be
 nylon or other appropriate material and is preferably non-flammable. The
 mesh 50 helps strengthen the flexible layer 14 and imparts desirable
 characteristics thereto. The mesh 50 is preferably a one-half inch by
 three-eighths inch mesh.
 The heating element 46 includes an electrical cable 54 disposed in the
 flexible layer 14 above the reflective sheet 42. The cable 54 is looped
 back and forth over the first layer 18 in a spaced-apart fashion such that
 the cable extends across the mat 10, as shown best in FIG. 2. The cable 54
 may be secured to the mesh 50, preferably by a structure such as tape 58
 as shown best in FIG. 2. It will be appreciated that the mesh 50 also
 helps maintain the relative position of the cable 54 with the cable 54
 secured thereto.
 The second layer 22 (see FIG. 4) is disposed over the heating element 46
 including cable 54. Thus, the heating element 46 and the reflective sheet
 42 are disposed in the mat 10 between the first and second layers 18 and
 22. The heating element 46 including the cable 54 is disposed over the
 reflective sheet 42 so that heat generated by the heating element is
 reflected upwardly by the reflective sheet 42.
 The cable 54 has a first end 62 extending out of the flexible layer 14 (see
 FIGS. 2 and 3). Electrical wires 64 included in the cable 54 are
 preferably attached to a plug 65 (for example an NEMA standard plug) which
 is disposed on the first end 62 of the cable and is adapted for being
 coupled to a source of electric current, or electric field. The
 electrically conductive cable 54 has an appropriate amount of electrical
 resistance such that the cable 54 heats as electricity flows therethrough,
 or in response to the applied electric field. The cable 54 also has a
 second end 66 (FIG. 2) which may terminate within the mat 10, or may have
 an electrical coupling as discussed more fully below.
 The cable 54 may be configured for use with a variety of electrical
 sources. For example, the cable 54 may be configured for use with standard
 electrical sources such as 120V AC at 50-60 cycles. The cable 54 may also
 be configured for 240V. The cable 54 may also be provided with an adaptor
 (not shown) to convert standard 120-240V AC to 12-20V DC. The cable 54 may
 be configured to enable a range of temperatures to be generated. For
 example, gauge and or length of the cable 54 may be varied to obtain the
 desired temperature of the heated mat 10.
 Referring to FIGS. 3 and 4, the heated mat 10 also has a thermostat or heat
 controller 70 disposed in the flexible layer 14. The thermostat 70 is
 electrically coupled to the heating element 46 or cable 54 as shown in
 FIG. 3. The thermostat 70 senses the temperature of the flexible layer 14,
 or second layer 22 or upper surface 38. Preferably, the thermostat 70 is
 disposed in the second layer 22 near the upper surface 38 to sense the
 temperature in the second layer 22 or the upper surface 38 as shown in
 FIG. 4.
 The thermostat 70 also controls the flow of electricity, or the applied
 electric field, to the cable 54. Thus the thermostat 70 senses the
 temperature of the mat and controls the current flowing in the cable
 accordingly to maintain the desired temperature. The thermostat 70 may
 preferably include a heat-sensitive switch electrically coupled in the
 cable in a series connection such that electricity flowing through the
 cable also flows through the switch. For example, the included in the
 thermostat 70 forms a connection at lower temperatures and interrupts the
 current flow at higher temperatures. Thus, electricity is allowed to flow
 through the switch, and thus the cable 54, at lower temperatures, but
 prevented from flowing through the switch, and thus the cable, at higher
 temperatures.
 Referring to FIGS. 2 and 3, a rubber sleeve 80 is preferably formed around
 the cable 54 at a portion 82 where it exits the flexible layer 14. A
 rubber sleeve 80 may also be formed around the second end 66 of the cable
 54 (FIG. 2). The sleeve 80 may seal the second end 66 of the cable 54 if
 it remains within the flexible layer 14, or strengthen the cable 54 at the
 portion 82 thereof which exits the flexible layer 14. In addition, an
 armored sheath 84 may be formed around the cable 54 extending from the
 flexible layer 14 for added protection from chewing, clawing and other
 damage, as shown in FIG. 3.
 Referring again to FIG. 1, the mat 10 may be configured for physically and
 electrically mating with adjacent mats to form a larger heated surface.
 The perimeter 44 of the mat 10, or flexible layer 14, may be shaped or
 configured to mate with other mats. The perimeter 44 may have a plurality
 of protrusions 88 and indentations or recesses 89. The protrusions 88 and
 indentations 89 may be shaped and sized to mate with protrusions and
 indentations on adjacent mats such that a continuous surface is formed.
 Thus, the mats are modular and can be combined together in various
 configurations.
 Referring again to FIG. 2, the second end 66 of the cable 54 may be
 provided with an electrical coupling as discussed above. The electrical
 coupling may be, for example, a female socket 90, as shown in FIGS. 2 and
 6a, or a male plug 92, as shown in FIG. 6b. Referring to FIG. 6b, the
 socket 90 and plug 92 may be integrally formed into the perimeter 44 of
 the mat 10, or flexible layer 14, such that an electrical connection is
 formed between adjacent mats when placed adjacent one another. Thus, the
 socket 90 and plug 92 preferably face outwardly from the flexible layer 14
 towards an adjacent mat. As shown best in FIGS. 6a and 6b, an electrical
 cable 96 is electrically coupled to the socket 90 and plug 92, and extends
 between the socket 90 and plug 92 to form a continuous electrical path
 between connected mats.
 Referring now to FIGS. 6a, 6b, 6b', 6b", 6c, 6d, 6e, and 6f, a number of
 mats with different internal electrical configurations can be provided in
 order to facilitate the creation of a larger heated surface. When a
 plurality of mats are connected together to form a larger heated surface
 the mats are also preferably referred to as a modular heated tile system.
 The mats may be disposed adjacent one another and electrically connected
 in a back and forth fashion, or alternating right and left directions, to
 form a larger surface. A starting modular mat 100 is provided for forming
 an electrical connection with a source of electrical current or an
 electrical field. Additional modular mats, such as an intermediate modular
 mat 110, may be disposed adjacent the starting modular mat 100 and
 additional mats can be placed adjacent to one another to form a strand or
 row of a desired dimension.
 As shown using FIGS. 6a, 6b, 6b', 6b", 6c, 6d, 6e, and 6f, a row running
 left to right is preferably first formed. A first end modular mat 120 and
 a second end modular mat 130 (FIGS. 6c and 6d) are used to start another
 strand or row adjacent to the first row. As shown, the first end modular
 mat 120 and the second end modular mat 130 form a column running back to
 front, or forming a bend, so that another similar row of mats may be
 connected running from right to left, including another intermediate
 modular mat 110 and a third modular end mat 140. Likewise, the third
 modular end mat 140 and a fourth end modular mat 150 (FIGS. 6e and 6f) are
 used to begin a third row running left to right. The end modular mats 120,
 130, 140 and 150 are interconnected with the intermediate modular mats 110
 until the desired number of rows is formed so that the larger heated
 surface provides the desired length and width. Therefore, any sized
 surface area may be created by the modular heated mat system of the
 present invention. Referring to FIG. 6a, the starting modular mat 100
 preferably includes an electrical plug 65 attached to wires 64 for
 receiving electrical current. It will be appreciated that the embodiments
 of the present invention can receive electrical power in any of a number
 of different ways now known or which may become known in the industry. The
 starting modular mat 100 is also provided with an electrical coupling,
 such as a female socket 90, disposed in the perimeter 44 of the mat 100.
 As shown, the cable 54 extends from the left edge of the mat 100 while the
 socket 90 is formed on an opposing right edge, or abutting edge, of the
 mat 100. It is of course understood that the cable 54 may extend from the
 mat at any appropriate location and that the socket may also be disposed
 at any appropriate location to facilitate coupling with an adjacent mat.
 Referring to FIG. 6b, the intermediate modular mat 110 is provided with a
 male plug 92b disposed at a left edge of the mat 110 and a female socket
 90b disposed at a right edge. The plug 92b is located to mate with the
 socket 90 of the starting modular mat 100. Thus, an electrical and
 physical connection is made between the two mats 100 and 110 as the plug
 92b engages the socket 90 and the tiles are held adjacent one another.
 As shown in FIG. 6b, the cable 54 of the heating element 46 extends through
 the mat 110 in a back and forth fashion between the plug 92b and the
 socket 90b to heat the flexible layer (such as 14 in FIG. 4) of the mat
 110. In addition, in each of the mats there is an electrical
 interconnection between the input of electrical power on the mat and the
 output provided on each of the mats. The interconnection is schematically
 represented in FIGS. 66a, 6b, 6b', 6b", 6c, 6d, 6e, and 6f at the
 connections 96, 96b, 96c, 96d, 96e, and 96f, which is preferably carried
 out using electrical conductors which can convey the necessary electrical
 current without appreciable heating. The connections 96, 96b, 96c, 96d,
 96e, and 96f provide that the plug on each mat (for example plug 92 in
 FIG. 6a) is electrically coupled to the socket (for example socket 90 in
 FIG. 6a) on each mat so that electrical current is conveyed from the plug
 to the socket on each mat without the current being conveyed through the
 cable (54 in FIG. 6a). In this way, electrical current is efficiently
 coupled from one mat to the next adjacent mat. In order to increase the
 width of the heated surface, intermediate modular mats 110 may be
 continued as desired until the appropriate dimension is reached.
 Referring to FIG. 6c, the first end modular mat 120 is also provided with a
 plug 92c for electrically coupling to the socket 90b of the intermediate
 modular mat 110. The mat 120 is also provided with a socket 90c located at
 an edge to couple with the next adjacent mat, such as mat 130 represented
 in FIG. 6d. Thus, the female socket 90c is disposed in an edge traverse or
 perpendicular to a side of the mat 120 in which the plug 92c is disposed.
 Referring again to FIG. 6d, the second end modular mat 130 is also
 provided with a plug 92d for coupling to the first end modular mat 120
 (FIG. 6c). In addition, the mat 130 is provided with a second plug 92d'
 for coupling to the socket 90b of another intermediate modular mat 110
 (FIG. 6b' and FIG. 6b"). Thus, the first and second end modular mats 120
 and 130 (FIGS. 6c and 6d) form an end of the strand or row of mats and a
 start to the next adjacent strand or row. Likewise, referring to FIGS. 6e
 and 6f, the third end modular mat 140 is provided with socket 90e and
 second socket 90e' while the and fourth end modular mat 150 is provided
 with plug 92f and socket 90f to form a continuous electrical path. While
 the first and second end mats 120 and 130 (FIGS. 6c and 6d) form a right
 end to the rows, the third and fourth mats 140 and 150 form a left end to
 the rows of heated mats which form a larger heated surface. The sockets
 90, 90b, 90c, 90e, 90e', and 90f and the plugs 92b 92c, 92d, 92d', and 92f
 can all be selected from sockets and plugs now available in the industry,
 or which will become available in the future, or provide the desired
 electrical and physical connection for the mats. The pattern suggested by
 FIGS. 6a, 6b, 6b', 6b", 6c, 6d, 6e, and 6f can be continued until a heated
 surface having the desired dimensions is formed.
 A preferred method of making the heated mats described above will now be
 explained. The preferred method of making the heated mats comprises the
 steps of providing a mold having a desired size, shape, and surface
 texture. It will be appreciated that the pattern represented on the
 surface of the mats depicted in FIGS. 1, 3, 6a, 6b, 6b', 6b", 6c, 6d, 6e,
 and 6f is provided on the upper surface of the mats and other patterns can
 be provided, or a pattern can be omitted, within the scope of the present
 invention.
 A first layer of recycled crumb rubber is placed into the mold with resin.
 A sheet of reflective material is placed on the first layer of crumb
 rubber. The sheet of reflective material preferably covers substantially
 all of the first layer but does not extend all the way to the perimeter of
 the mold and thus will not extend to the perimeter of the finished mat.
 A conductive wire (such as described in connection with FIG. 2) is placed
 over a layer of mesh (also such as described in connection with FIG. 2) in
 a desired configuration. For example, the wire may be formed back and
 forth across the mesh. The wire is preferably secured to the mesh with
 tape. The wire is placed over the reflective material and the first layer
 of crumb rubber. A thermostat may also be electrically coupled to the wire
 and disposed in the mold (as preferably depicted in FIG. 3).
 A second layer of recycled crumb rubber with resin is placed over the wire,
 the sheet of reflective material, and the first layer of crumb rubber. The
 mold and the crumb rubber is then heated under pressure.
 The crumb rubber preferably used to fabricate the embodiment of the present
 invention can be obtained from many different sources and is preferably
 obtained from recycling used tires and as otherwise described in U.S. Pat.
 No. 5,234,171 and European Patent Publication No. 0 484 296 A1, both of
 which are now incorporated herein by this reference in their entireties as
 well as all patent documents referred to therein are also incorporated
 herein in their entireties.
 As described above, the finished heated mat is preferably made of a
 recycled crumb rubber which is of high quality, uncontaminated, and
 uniformly sized. The present invention provides a heated mat which is
 particularly adapted for use with animals and which is made of
 inexpensive, non-allergenic, recycled material. The present invention also
 provides a heated mat which can be physically and electrically coupled
 with other mats to conveniently form a larger heated surface.
 The present invention may be embodied in other specific forms without
 departing from its spirit or essential characteristics. The described
 embodiments are to be considered in all respects only as illustrative and
 not restrictive. The scope of the invention is, therefore, indicated by
 the appended claims rather than by the foregoing description. All changes
 which come within the meaning and range of equivalency of the claims are
 to be embraced within their scope.