Cross Reference To Related Application

This application claims the benefit of U.S. Provisional Patent Application No. 61/139,345, filed December 19, 2008, and U.S. Patent Application No. 12/392384, filed February 25, 2009, the disclosures of which are incorporated by reference herein in their entirety.

Background

The present invention relates generally to drop cloths and, more particularly, to a drop cloth having a bendable shape retaining member that allows a user to form the drop cloth to closely match the profile of a protected surface.

Protective sheets, such as drop cloths and tarps, are commonly used by painters to protect surfaces from, for example, paint spills, drips, splattering, and overspray. The surfaces to be protected vary widely and may include, for example, floors, carpet, furniture, stairs, banisters, cabinets, countertops, and landscaping. To adequately protect such surfaces, the drop cloth must be carefully positioned around and along corners, columns, and other oddly shaped or contoured surfaces.

Drop cloths are known in the prior art. U.S. Patent No. 3,862,876 (Graves) for example, discloses a protective cover cloth having continuous flexible weights secured along at least two opposed edges for securing the cover against wind blowing, etc. The cover cloth may be made from insulated materials and heated for curing concrete. Sand, shot or other particulate material, possibly in individual bags, is inserted in a wide hem or tubes attached along the edges of the cover.

In U.S. Patent No. 5,930,956 (Trosper et al), an easily and quickly deployable device for protecting against soiling of non-workpiece items during painting of a workpiece is provided by a device having at least one rigid section and at least one flexible section. The rigid section also acts as a central area for the flexible section. The device is folded open to protect non-workpiece items during the painting operation Summary

The need exists for a lightweight drop cloth that can be accurately positioned along and around a variety of contoured surfaces. The need also exists for such a drop cloth that is affordable, easy to make, and easy to use. More particularly, the need exists for a drop cloth that behaves similar to existing drop cloths, but which is capable of being repeatedly manipulated by a user to match desired profiles, thereby allowing the user to better protect an underlying surface. More particularly, the need exists for a drop cloth that includes a portion that is self supporting (i.e. can support its own weight). The need also exists for a drop cloth that will retain a selected shape until the user actively changes the shape. The need also exists for such a drop cloth that can be readily returned to a generally flat condition after being shaped, and can be easily folded for storage and transportation purposes.

It would be desirable to provide a drop cloth having a conformable shape retaining member that allows a user to manually manipulate a portion of the drop cloth to easily and accurately match the profile of a surface to be protected. It would also be desirable to provide such a drop cloth that is similar to conventional drop cloths in terms of its performance characteristics (e.g. durability, ability to be folded or formed into a roll for storage), appearance, cost, weight, and handling.

The present disclosure provides a drop cloth comprising a flexible sheet material having a perimeter edge region, and a conformable shape retaining member arranged adjacent to at least a portion of the perimeter edge region that allows the drop cloth to be easily and accurately formed to match the profile of a surface to be protected.

In various more specific aspects, the conformable shape retaining member may be metal, the conformable shape retaining member may be a bendable sheet of metal, the conformable shape retaining member may be self supporting (i.e. able to support its own weight), the conformable shape retaining member may be able to support its own weight and the weight of the flexible sheet material, the conformable shape retaining member may be a continuous sheet of material having a length of at least about 3 feet, the conformable shape retaining member may be a sheet of material having a thickness of at least about 1.0 mil, or at least about 3.0 mil, and a thickness of no greater than about 6.0 mil, or no greater than about 10.0 mils, the conformable shape retaining member may be a sheet of material having a width of at least about one (1) inch, the conformable shape retaining member may be a sheet of material having a width of about two (2) inches to about six (6) inches, the conformable shape retaining member may be formed of aluminum, the conformable shape retaining member may be formed of untempered aluminum, the conformable shape retaining member may be an embossed sheet of metal, the embossed sheet of metal may include a random or irregular distribution, or arrangement, of raised and recessed regions, the embossed sheet of metal may include a regular pattern of aligned raised and recessed regions, such as a rectilinear array of uniformly sized and shaped raised and/or recessed regions, the regular embossed pattern may be embossed in a small brick pattern with features having dimensions of at least about 1/8" by 1/32", the drop cloth may include a pair of conformable shape retaining members arranged along opposite edges of the drop cloth, the drop cloth may further comprise a conformable shape retaining member arranged only along an edge portion of the drop cloth, and/or in a central region of the drop cloth, the conformable shape retaining member may be arranged in a discontinuous manner with the flexible sheet material (i.e. arranged adjacent selected regions of the flexible sheet material), the conformable shape retaining member may be affixed or adhered to the flexible sheet material, the flexible sheet material may include an elongate pouch wherein the conformable shape retaining member is contained within the elongate pouch, the conformable shape retaining member may be affixed to an outer surface of the flexible sheet material, the flexible sheet material may be at least one of cloth, paper, and polymeric film, the conformable shape retaining member may be manually formed by a user from an undeformed configuration, to a second deformed configuration, and then returned substantially to the undeformed configuration, and/or the drop cloth may have a flexural recovery value of less than about 40 degrees, 30 degrees, 20 degrees or 15 degrees when measured according to ASTM D 3768-06 after being bent 90 degrees after 30 second recovery (i.e. the difference between the 90 degree bend and the recovered bend angle after a 30 second recovery period may be less than about 40 degrees, 30 degrees, 20 degrees, or 15 degrees).

In another embodiment, the present disclosure provides a drop cloth consisting of a flexible sheet material having a perimeter edge region, a conformable shape retaining member arranged adjacent at least a portion of only the perimeter edge region, and means for retaining the conformable shape retaining member along a region of the flexible sheet material. In a more specific embodiment, the present disclosure provides a drop cloth comprising a sheet of canvas material having a perimeter edge region containing a pouch, a conformable shape retaining member arranged adjacent at least a portion of the perimeter edge region, the conformable shape retaining member comprising an elongated sheet of embossed aluminum having a length of at least 3 feet, a width of at least 3 inches, and a thickness of about 3 mils to about 7 mils. The shape retaining member may be secured to the flexible sheet material using, for example, conventional mechanical fasteners, hook-and-loop-type fasteners, adhesive, thread (i.e. by sewing), by coating the shape retaining member material directly onto the flexible sheet material, by lamination, extrusion, or adhesively bonding the sheet material to the flexible sheet material, or the shape retaining member may be loosely arranged within the pouch (i.e. not secured to the flexible sheet material).

In this application:

"Conformable shape retaining member" refers to a member that can be repeatedly manually bent, formed or otherwise shaped into various configurations, and that will generally retain a desired configuration under the force of gravity.

"Dead fold" refers to the ability of, for example, a sheet-like or elongated material to take and hold a fold without springing back.

"Embossing" refers to a process used to imprint a metal layer with a pattern of depressions.

"Untempered metal" refers to a metal that has not undergone heat treating to increase its durability; tempering increases the toughness of the metal but also decreases its ductility.

An advantage of certain embodiments described herein include providing a versatile and lightweight drop cloth that can be repeatedly manually manipulated by a user to conform to the profile of a surface to be protected. Additional advantages include providing such a drop cloth that is easy to make and easy to use. A more specific advantage includes providing a drop cloth with a conformable shape retaining member arranged along at least a portion of an edge of the drop cloth that can be readily formed by a user to closely match the profile of a surface to be protected. Brief Description of the Drawings

The present invention will be further described with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a drop cloth according to the present disclosure;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a perspective view of an embodiment of a conformable shape retaining member;

FIG. 4 is a perspective view of a drop cloth according to a second embodiment;

FIG. 5 is a perspective view of a drop cloth according to a third embodiment; and

FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 5.

Detailed Description

Referring now to the drawings, FIGS. 1-2, show a drop cloth 2 including a flexible sheet material 4, and a conformable shape retaining member 6. Throughout the description and the accompanying figures, functionally similar features are referred to with like reference numerals incremented by 100.

The flexible sheet material 4 includes first and second opposed major surfaces 8a, 8b, a perimeter edge region 10, a central region 12, first and second opposed side edges 14a, 14b, and first and second opposed end edges 16a, 16b. The flexible sheet material 4 may be formed of any material used to form a conventional drop including inexpensive disposable materials, such as paper and polymeric films, more durable reusable materials, such as woven fabrics including light weight cotton sheets and canvas, nonwoven materials, or from combinations of such materials. The flexible sheet material 4 may have any desired size such as, for example, a standard 9 foot by 12 foot size, or custom sizes such as, for example, a 1 foot by 12 foot size. The flexible sheet material 4 may optionally include a coating, such as a rubberized coating, on one side to provide slip resistance, puncture resistance, and to provide a leak proof barrier. The flexible sheet material 4 may also be provided with a flame retardant treatment. In certain embodiments, the flexible sheet material 4 is a woven fabric having a weight of at least 2 ounces per square yard (oz/sq ² ), at least 3 oz/sq ² , or at least 4 oz/sq ² , and a weight of no greater than 12 oz/sq ² , 14 oz/sq ² , or 16 oz/sq ² . In a desirable embodiment, the flexible sheet material 4 is a 4-12 oz/sq ² canvas cloth. In an alternative embodiment, the flexible sheet material 4 may be a fire resistant material so the drop cloth 2 can be used as a welding blanket to protect an underlying surface from, for example, sparks generated during a welding operation. Suitable fire resistant materials include those materials used in conventional welding blankets. Welding blankets may be made of fiberglass, which is advantageous due to its high melting temperature of around 1000 ⁰ F and continuous operating temperature of 65O ⁰ F. Welding blankets may also be made of silica, which is fiberglass that undergoes a chemical treatment to remove impurities and has a melting point of about 3000 ⁰ F. Such blankets may also be coated with a variety of chemicals. For example, aluminum coatings may be used to provide heat reflectivity, acrylic coatings may be used to provide additional durability, and hypalon coatings may be used to increase strength and abrasion resistance. Leather may also be used to cover and protect surfaces during the welding process.

In the embodiment illustrated in FIG. 1, the conformable shape retaining member 6 is arranged along substantially the entire length of the second side edge 14b of the edge region 10 of the sheet material 4. More particularly, in the illustrated embodiment, the conformable shape retaining member 6 is arranged along only an edge portion of the drop cloth 2. By providing the shape retaining member 6 along only the edge portion of the drop cloth 2, the amount of weight added to the drop cloth construction by the conformable shape retaining member 6 is minimized. It will be recognized that the shape retaining member 6 may be arranged along the entire perimeter edge region 10 of the sheet material 4, or arranged along only selected portions of the perimeter edge region 10.

As shown in FIG. 2, the conformable shape retaining member 6 is contained within an elongated pouch 18 formed along the edge region 10 of the sheet material 4. The pouch 18 is formed by folding the sheet material 4 back over onto itself in overlapping relation, and sewing the sheet material 4 together with stitching 20. To enclose the shape retaining member 6 within the pouch 18, the shape retaining member 6 may be placed along either the edge of the sheet material 4 prior to stitching the sheet material 4 to itself, or the shape retaining member 6 may be inserted into the end of the pouch 18 after the elongate stitch 20 is made, but before the ends of pouch 18 are closed. The pouch 18 may then be closed by sewing the ends of the pouch closed. Formed as such, the pouch 18 extends along the entire second side edge 14b of the sheet material 4, and the shape retaining member is contained within the pouch 18. In other embodiments, the pouch 18 may be formed by securing the sheet material 4 to itself using, for example, mechanical fasteners, tape, or other adhesive.

In a desirable embodiment, the stitching 20 used to form the pouch 18 may be color coded to indicate the size of the drop cloth. For example, a 9 foot by 12 foot drop cloth may be designated using a blue colored thread, and a 12 foot by 15 foot drop cloth may be designated using a red colored thread. In this manner, when the drop cloth 2 is folded or formed into a roll to be put away, the end user can easily determine the size of the drop cloth 2 from the color of the thread, a portion of which will remain either visible or easily accessible regardless of how the drop cloth 2 has been folded. Alternatively, the edge or a portion of the edge of the drop cloth 2 may be printed with a visual indicia, such as words, symbols, a pattern, a design, or a color using, for example, a rotary printer, to indicate the size of the drop cloth 2.

In accordance with another desirable aspect of the disclosure, the conformable shape retaining member 6 is formed of a material having good dead fold properties. The dead fold property of a material depends on a number of variables including, for example, the type of material (e.g. a metal versus a synthetic plastic material; aluminum versus brass), if the material is a metal, whether the metal has been heat treated (e.g. annealed, tempered, or quenched) or work hardened (e.g. cold rolled or shot peened), and the geometry of the material, particularly the thickness of the material. Materials capable of forming conformable shape retaining members 6 having suitable dead fold properties include thin sheets of metals such as aluminum, copper, tin, steel, lead, silver, gold, including combinations and alloys of such metals, some papers, papers laminated to plastic films, paper or plastic films with metal coatings, or other combinations of such materials. The shape retaining member 6 may be formed of a single layer of material, or it may have a multi-layer construction. Multi-layer constructions may comprise, for example, a plurality of layers of either the same or different type of materials. The particular material selected for each layer, and the particular thickness of each layer is not critical so long as the overall construction exhibits the desired properties.

In another aspect, the shape retaining member 6 is self-supporting (i.e. it is able to support its own weight). In a more specific aspect, the shape retaining member is able to support its own weight plus the weight of the associated flexible sheet material 4 (i.e. the weight of the adjacent or surrounding flexible sheet material).

A particularly desirable material for forming the shape retaining member 6 is an untempered (i.e. zero temper) aluminum foil, which may or may not be embossed, having a thickness of approximately 4-6 mils. This material was found to have a desirable combination of properties including light weight, low cost, good durability, good flexural recovery and dead fold properties, and easily formed by hand.

In a related aspect, the conformable shape retaining member 6 has a suitable flexural recovery value. Flexural recovery relates generally to the extent to which a material freely recovers (i.e. recovers on its own) after being bent. ASTM test standard D 3768-06 provides a test method for measuring the flexural recovery of microcellular urethanes. This test method was used to measure the flexural recovery of several shape retaining members and drop cloth constructions (i.e. a combination of a shape retaining member and a flexible sheet material) having desirable dead fold characteristics. The shape retaining members included a flat untempered sheet of aluminum, a flat hardened sheet of aluminum, and an embossed sheet of untempered aluminum, each having a thickness of approximately 4-6 mils. It was found that desirable shape retaining members and/or drop cloth constructions including both a shape retaining member and a flexible sheet material, such as canvas, have a flexural recovery value as measured according to ASTM D 3768-06 when bent 90 degrees after 30 second recovery, of no greater than about 40 degrees, no greater than about 30 degrees, no greater than about 20 degrees, or no greater than about 15 degrees.

The shape retaining member 6 may optionally include a coating layer to provide the shape retaining member 6 with enhanced properties, such as improved durability or corrosion resistance, provided the coating layer does not unduly interfere with the dead fold properties of the shape retaining member 6. Suitable coating layers may be formed of, for example, polymers including elastomeric materials, such as acrylic latex. The coating layer may be provided on only selected regions of the shape retaining member such as, for example, along the edges of the shape retaining member, or on the entire outer surface of the shape retaining member. Alternatively, the longitudinal edges of the shape retaining member may be bent, folded, or crimped. Coating or mechanically modifying the edges of the shape retaining member may facilitate the insertion of the shape retaining member into the drop cloth during production or replacement, and reduces the propagation of tears that may form in the shape retaining member during use.

In one embodiment, the conformable shape retaining member 6 is formed of zero temper, or untempered, aluminum foil. Suitable untempered aluminum alloys include, for example, alloys 1100-0, 1145-0, 6061-0, or 3003-0 available from All-Foils Inc., Cleveland, OH., having a suitable thickness. In one aspect, the conformable shape retaining member 6 is formed such that it does not spring back significantly when folded. That is, when the shape retaining member 6 is folded over onto itself in overlapping and contacting relation, and is then released, the folded portion of the shape retaining member 6 will remain substantially adjacent the folded portion. In a more specific aspect, a drop cloth construction including the combination of a flexible sheet material 4 and a shape retaining member 6 does not spring back significantly when folded. That is, the dead fold property of the shape retaining member 6 is great enough to maintain the shape of the drop cloth 2 during use. Or stated another way, the combination of the flexible sheet material 4 and shape retaining member 6 will retain a selected shape until the user actively changes the shape.

The shape retaining member 6 has a size and shape that allows it to be readily bent by hand. The shape retaining member 6 may be, for example, a relatively thin, flat, elongated sheet of metal material, such as a metal foil. The shape retaining member 6 may be continuous and planar, discontinuous (e.g. perforated), and/or be provided with a three- dimensional surface topography. For example, the shape retaining member 6 may be embossed to produce a desired three-dimensional surface topography. Such an embossed material may include, for example, a regular repeating pattern of geometric shapes, such as circles, squares, or diamond-shaped indentations or recesses. In addition, the embossed pattern may include a random array of raised and recessed regions. Even though embossing tends to harden metals, and thereby generally tends to reduce their durability, because embossed sheet materials tend not to repeatedly crease along the same fold line, embossing tends to minimize the unwanted effect of bending fatigue on the shape retaining member, thereby reducing the likelihood that the shape retaining member will fail prematurely due to metal fatigue.

In some embodiments, the shape retaining member 6 in the form of an elongate sheet of material may have a length of at least about 3 feet, but may have a length generally corresponding to the length of the drop cloth 2, which may be 4 feet, 12, feet, 15 feet, or more. In addition, a sheet- like shape retaining member 6 may have a width of at least about 1 inch, at least about two inches, or at least about 3 inches, and a width of no greater than about 24 inches, no greater than about 16 inches, no greater than about 12 inches, or no greater than about 6 inches.

The thickness of the sheet- like shape retaining member 6 has been found to be an important parameter in the design of the drop cloth 2. If the sheet like retaining member 6 is too thin, it may not adequately retain its own shape, or the shape of an associated drop cloth, under the force of gravity. Alternatively, if the sheet retaining member 6 is too thick, it may become difficult to manually bend and return to a desirable unbent condition, it may not hold its shape after it has been bent, and it may add unwanted weight and expense to the drop cloth construction. Suitable sheet-like shape retaining members may have a thickness of at least about 1.0 mil, at least about 2 mils, or at least about 3 mils, and a thickness of no greater than to about 15 mils, no greater than about 12 mils, no greater than about 10 mils, or no greater than about 8 mils.

FIG. 3 illustrates a conformable shape retaining member 6 embossed with an exemplary three-dimensional surface topography having raised 22a and recessed regions 22b. As alluded to previously, embossing is advantageous because it increases the formability, and enhances the conformability, of the shape retaining member 6. Embossing also minimizes the likelihood that the shape retaining member 6 will repeatedly crease along a common fold line, which may result in metal fatigue and, ultimately, in premature failure of the shape retaining member 6.

The shape retaining member 6 may be embossed in a variety of patterns. For example, the shape retaining member 6 may be a sheet of metal embossed in a small brick pattern with features having dimensions of at least about 1/8" by 1/32", and with spaces between the features with dimensions of at least about 1/8" by 3/32". The shape retaining member may also be embossed in a large brick pattern with features having dimensions of at least about 7/16" by 5/16" and with spaces between the features with dimensions of at least about 1/2" by 13/16". The embossing pattern may also be a diamond pattern with features having dimensions of about 1/8" by 1/8" and with spaces between the features having dimensions of at least about 3/16" by 3/16". The embossing pattern may also have circular features with a diameter of at least about 1/16" and with spacings of at least about 1/16". The shape retaining member may also be embossed with an irregular or random pattern. A material having a suitable random pattern is available from Henan Yinhu Aluminum Industry Co. Ltd, Henan, China.

The conformable shape retaining member 6 may also be in the form of a single bare wire, a plurality of wires, wire with a paper covering similar to a "twisty tie", or it may have a wire mesh structure similar to "chicken wire". In addition, any of the shape retaining members 6 described herein may be provided with a coating, such as an elastomeric coating (e.g. latex), so long as such coating does not interfere with the desired functional properties of the shape retaining member 6. Such a coating may, for example, serve to increase the life of the shape retaining member, provide the shape retaining member 6 with enhanced corrosion resistance, and/or conceal sharp edges that may otherwise damage the sheet material 4.

Suitable shape retaining members 6 will generally have a structure or geometry (e.g. a size and shape), and will be formed of a material, that allows them to be manually formed into various configurations. That is, the conformable shape retaining member may be manually formed by a user from a first undeformed configuration, such as an unfolded or flat (i.e. generally planar) condition, to a selected second deformed configuration, such as around a corner along a floor, and then returned substantially to the first undeformed configuration, whereupon the drop cloth 2 may be folded and stored, or repositioned. It is desirable that the shape retaining member 6 maintain its shape, as well as the shape of the sheet material 4, once the shape retaining member 6 and sheet material 4 have been arranged in a desired position. In another aspect, it is desirable that a user be able to manually return the shape retaining member 6 substantially to its original configuration, such as a flat or straight condition.

In a desirable embodiment, the drop cloth 2 includes a flexible sheet material 4 formed of canvas, such as a 4-12 oz/sq ² canvas, which includes a sewn perimeter edge region defining a pair of elongated pouches 18 along opposite edges of the sheet material 4. A pair of conformable shape retaining members 6 are arranged within each of the elongated pouches. The conformable shape retaining members 6 comprise an elongated embossed sheet of zero temper aluminum having a length generally corresponding to the length of the drop cloth 2, a width of about 2 to about 6 inches, and a thickness of about 3 mils to about 6 mils. In one embodiment, the embossed pattern includes circular embossed regions each having a depth of at least about 0.01 and no greater than about 0.04 inches, an area of at least about 7 square millimeters (mm ² ), and the embossed regions are spaced apart - as measured from the center of one embossed region to the center of the next closest embossed region - by a distance of about 5 millimeters.

In the embodiment illustrated in FIG. 4, the drop cloth 102 includes a pair of conformable shape retaining members 106a, 106b arranged along opposite edges 114a, 114b of the drop cloth, and a third conformable shape retaining member 106c extending through the central region 112 of the drop cloth 102 from the first edge 114a to the second edge 114b, thereby forming an H-shaped pattern. It will be recognized that other patterns and arrangements for the shape retaining members are possible. For example, the third shape retaining member 106c may be arranged at various locations or angles between the pair of shape retaining members 106a, 106b, (such as parallel, angled, equidistant, or offset), additional shape retaining members may be provided between the pair of shape retaining members 106a, 106b, or one or more shape retaining members may be provided along the entire outer perimeter edge region 110 of the drop cloth 102 (i.e. along the first and second side edges 114a, 114b, and along the first and second end edges 116a, 116b).

Referring now to FIGS. 5 and 6, there is shown another embodiment of a drop cloth 202 similar to the embodiment illustrated in FIGS. 1 and 2 except the shape retaining member 206 is affixed to the first major outer surface 208a of the flexible sheet material 204, rather than being contained in a pouch 18 as illustrated in FIGS. 1 and 2. The shape retaining member 206 may be affixed to the sheet material 204 using an adhesive such as glue, a pressure-sensitive adhesive such as a repositionable adhesive or a hot melt pressure sensitive adhesive, or using double-sided tape, mechanical fasteners such as staples, by sewing the shape retaining member 206 directly to the sheet material 204, or using a refastenable mechanical attachment mechanism, such as hook-and-loop type fasteners.

In order that the invention described herein can be more fully understood, a number of shape retaining members and drop cloth constructions were evaluated to characterize their flexural recovery properties using ASTM Test Standard D 3768-06 (Standard Test Method for Microcellular Urethanes - Flexural Recovery). It should be understood that these samples are for illustrative purposes only, and are not to be construed as limiting this invention in any manner. In each Example, the shape retaining member had the thickness specified in Table I below, was 25 mm in width, and 150 mm in length (1 by 6 inches). In Examples where a flexible sheet material is present, a 10 oz/sq ² 100% cotton canvas was used. To perform the test, and to more accurately simulate the construction of a drop cloth construction wherein the shape retaining member is contained within a pouch, a sample of sheet material having a width of 5 centimeters (cm) and a length of 15 cm was folded in half, thereby forming a test sample having a width of 2.5 cm and a length of 15 cm. Additional details for each sample (e.g., whether the shape retaining member was heat treated or embossed, whether it was a shape retaining member alone, or a composite drop cloth construction including both a shape retaining member and a flexible sheet material) are presented in Table I below, together with the measured flexural recovery value.

Table I

1 - the embossing pattern was a small circle pattern wherein each circle feature had a dimension of about 1/32 inch (0.8 mm), and the features were spaced apart by about 3/32 inch (2.5 mm). The sample was tested with the embossed features facing outwardly (i.e. away) from the mandrel.

Persons of ordinary skill in the art may appreciate that various changes and modifications may be made to the invention described above without deviating from the inventive concept. Thus, the scope of the present invention should not be limited to the structures described in this application, but only by the structures described by the language of the claims and the equivalents of those structures.