Patent Publication Number: US-2004045955-A1

Title: Electric heating/warming fabric articles

Description:
[0001] This application claims benefit from U.S. application Ser. No. 60/386,180, filed Jan. 14, 2002, now abandoned, the complete disclosure of which is incorporated herein by reference. 
    
    
     
       TECHNICAL FIELD  
       [0002] The invention relates to electrical resistance heating/warming textile articles.  
       BACKGROUND  
       [0003] Techniques known for augmenting heating/warning capabilities of clothing fabric include adding electric wires to the fabric, typically by incorporating the wires directly into the fabric or by attaching the wires to the fabric, e.g., by sewing. It is also known, e.g., from Gross et al. U.S. Pat. No. 4,021,640, to print an electrical circuit with a resistance heating element on a plastic sheet, such as MYLAR®, and to incorporate strips of the plastic sheet into a fabric article, such as a glove.  
       SUMMARY  
       [0004] In one aspect, the invention features a method of forming an electric heating/warming fabric article, the method comprising: (a) configuring a conductive sheet-form layer comprising a metallized sheet or a conductive textile into an electrically conductive circuit pattern; and (b) attaching the circuit pattern to one of a first and a second broad surface of a fabric body for producing localized heating of the fabric body upon application of electrical current to the circuit pattern.  
       [0005] Using a sheet-form conductive layer to form the circuit pattern provides a robust, flat, and pliable heating/warming element that can be easily manufactured and readily attached to a textile to form a fabric article. The flexible nature of the conductive layer provides good dexterity when the heating/warming element is used in a glove or other article of clothing in which flexibility is useful. The sheet-form conductive layer can also be readily configured in various circuit patterns and geometries, e.g., to provide differential heating to different areas of an article, as will be discussed further below.  
       [0006] Some implementations of this aspect of the invention may include one or more of the following features. The configuring step includes die-cutting. The conductive layer includes a metallized sheet material selected from the group consisting of metallized textiles, metallized plastic sheeting, and metal foils. The configuring step includes subjecting a sheet material to metal coating, plating or deposition. The attaching step includes joining the conductive layer and fabric body with adhesive. The term “adhesive,” as used herein, refers to any material that will join the layers, including both liquid adhesives and non-liquid, flowable materials such as hot melt webs (commercially available, e.g., from Bostik Co.).  
       [0007] The method further includes forming an article of clothing including the fabric body. The forming step includes shaping the circuit pattern to conform to the shape of the article of clothing. The article of clothing includes an article selected from the group consisting of gloves, socks, sweaters, jackets, shirts, pants, hats, and footwear.  
       [0008] In some implementations, by varying the effective electricity-conducting volume, e.g., the cross-sectional area, of the heating/warming element in selected regions, the level of heat generation can be controlled. (For heating/warming elements of uniform thickness, e.g., those formed of metal foil, the effective volume is typically adjusted by variation of the width and/or length.) For example, in a heating/warming element of the invention for use in a shoe, the volume of the heating/warming element in the region of the toes may preferably be less than its volume in the heel region, thus creating greater resistivity in the region of the toes and greater heat generation. Similarly, for use in gloves, the effective volume of the heating/warming element in the region of the fingers will preferably be less (for greater resistivity and heat generation) than in the palm region.  
       [0009] The method further includes configuring the circuit pattern to include areas of relatively higher resistivity and areas of relatively lower resistivity to provide predetermined regions of relatively higher and relatively lower localized heating. The predetermined areas of relatively higher and relatively lower resistivity are provided by varying the cross-sectional area of one or more selected regions of the circuit pattern. The predetermined areas of relatively higher and relatively lower resistivity are provided by varying the conductivity of one or more selected regions of the conductive layer. The electric heating/warming article is incorporated into an article of clothing, and the method further includes configuring the circuit pattern to place the areas of relatively higher resistivity adjacent a wearer&#39;s extremities when the article of clothing is worn, and/or to place the areas of relatively higher resistivity adjacent regions of the wearer&#39;s body where blood flow is close to the skin surface when the article of clothing is worn. This allows more heat to be delivered to the extremities, which are prone to vasorestriction in cold weather.  
       [0010] The method may also include interposing a barrier layer between the fabric body and the sheet-form conductive layer, e.g., by attaching an outer surface of the barrier layer to the fabric layer, and attaching an inner surface of the barrier layer to the sheet-form conductive layer. The attaching steps may include joining the layers with adhesive. A barrier is generally used if wind protection is desired.  
       [0011] The method further includes connecting the circuit pattern to a power source, to generate heating/warming. The method further includes incorporating the electric heating/warming fabric article into a home textile article, e.g., a blanket, throw, mattress cover or sleeping bag.  
       [0012] In another aspect, the invention features a heating/warming fabric article, including: (a) a fabric layer having an inner surface and an outer surface, and, (b) attached to the inner surface of the fabric layer, a sheet-form conductive layer including an electrically conductive circuit pattern for producing localized heating of the fabric article upon application of electrical current to the circuit pattern.  
       [0013] Some implementations of this aspect of the invention include one or more of the following features. The fabric layer includes a textile material selected from the group consisting of weft knitted materials, warp knitted materials, woven materials, and nonwoven materials. The fabric layer may have a smooth surface, a raised surface, or a brushed surface. The fabric article is an article of clothing. The fabric article is a blanket. The article of clothing includes an article selected from the group consisting of gloves, socks, sweaters, jackets, shirts, pants, hats, footwear, accessories such as ear muffs and neck warmers, and braces and pads such as medical braces, medical bands, knee pads, back pads, and joint pads.  
       [0014] The circuit pattern includes areas of relatively higher resistivity and areas of relatively lower resistivity to provide predetermined regions of relatively higher localized heating and predetermined regions of relatively lower localized heating. The areas of relatively higher and relatively lower resistivity include regions of relatively lesser and relatively greater cross-sectional area, respectively. The fabric article includes an article of clothing, and the circuit pattern is configured to place the areas of relatively higher resistivity adjacent a wearer&#39;s extremities when the article of clothing is worn, and/or to place the areas of relatively higher resistivity adjacent regions of the wearer&#39;s body where arteries are close to the skin surface when the article of clothing is worn.  
       [0015] The conductive layer includes a sheet-form material selected from the group consisting of metallized textiles, metallized plastic sheeting, and metal foils. The fabric article further includes adhesive interposed between the metallized layer and fabric body. The fabric article may further include a barrier layer between the fabric layer and sheet-formed metallized layer. The fabric layer, sheet-formed conductive layer, and barrier layer (if present) are joined by adhesive.  
       [0016] The fabric article further includes a temperature sensor for measuring the temperature of a portion of the circuit pattern. The temperature sensor is configured to measure the temperature of a first portion of the circuit pattern, and the first portion of the circuit pattern is configured to have the same resistance as a second portion of the circuit pattern, to allow the temperature of the second portion to be estimated by measuring the temperature of the first portion. The fabric article further includes a controller configured to adjust the power supplied to the circuit pattern in response to changes in the measured temperature.  
       [0017] In a further aspect, the invention features a method of forming an electric heating/warming fabric article, the method including: (a) die-cutting a sheet-form conductive layer to form an electrically conductive circuit pattern wherein a first portion of the conductive layer is relatively narrower to increase localized heating and a second portion of the conductive layer is relatively wider to decrease localized heating; (b) attaching the circuit pattern to an outer surface of a fabric body; (c) incorporating the fabric body into an article of clothing; and (d) connecting a power source to the circuit pattern, thereby producing localized heating of the fabric body upon application of electrical current to the circuit pattern. In step (a), the second portion of the conductive layer may be made sufficiently wide that the second portion does not heat up at all, and functions only as a bus.  
       [0018] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings.  
     
    
    
     DESCRIPTION OF DRAWINGS  
     [0019]FIGS. 1 and 1A are somewhat diagrammatic exploded side edge views of the components forming the first embodiments of a heating/warning composite fabric article constructed in accordance with the invention;  
     [0020]FIG. 2 is a somewhat diagrammatic side edge view of the heating/warming composite fabric article of FIG. 1; and  
     [0021]FIGS. 3, 4 and  5  are somewhat diagrammatic front plan views of the inner surfaces of heating/warming composite fabric articles of FIGS. 1 and 2, with electric heating/warming elements affixed thereupon, e.g., for a glove (FIG. 3), for an article of footwear (FIG. 4), and for a garment such as a shirt or jacket (FIG. 5); and  
     [0022]FIG. 6 is a somewhat diagrammatic front view of a garment, i.e., a jacket, incorporating the heating/warming composite fabric article of FIG. 5.  
     [0023]FIG. 7 is a somewhat diagrammatic exploded side edge view of the components forming another embodiment of a heating/warming composite fabric article constructed in accordance with the invention; and  
     [0024]FIG. 8 is a somewhat diagrammatic side edge view of the heating/warming composite fabric article of FIG. 7.  
     [0025]FIG. 9 is a somewhat diagrammatic side edge view of another embodiment of a heating/warming composite fabric article constructed in accordance with the invention.  
     [0026]FIGS. 10 and 11 are sequential, somewhat diagrammatic front plan views of the inner surface of a heating/warming composite fabric article during construction in accordance with another embodiment the invention.  
     [0027]FIG. 12 is a somewhat diagrammatic exploded side edge view of the components forming another embodiment of a heating/warming composite fabric article constructed in accordance with the invention, while FIGS. 13 and 14 are somewhat diagrammatic side edge views of alternate embodiments of the heating/warming composite fabric article of FIG. 12.  
     [0028]FIGS. 15 and 16 are somewhat diagrammatic front plan views of an electric heating/warming element for use in a glove.  
     [0029]FIG. 17 is a somewhat diagrammatic front plan view of an electric heating/warming element for use in a glove, including a temperature sensing element.  
     [0030]FIG. 18 is a somewhat diagrammatic front plan view of an electric heating/warming element that includes a parallel circuit.  
     [0031]FIG. 19 is a somewhat diagrammatic front plan view of an electric heating/warming element for use in an article of footwear. 
    
    
     [0032] Like reference symbols in the various drawings indicate like elements.  
     DETAILED DESCRIPTION  
     [0033] This application relates to the disclosure of our prior co-pending patent applications U.S. application Ser. No. 09/298,722, filed Apr. 23, 1999, U.S. application Ser. No. 09/389,761, filed Sep. 9, 1999, U.S. application Ser. No. 60/175,202, filed Jan. 10, 2000, U.S. application Ser. No. 60/261,544, filed Jan. 12, 2001, and U.S. application Ser. No. 60/386,180, filed Jan. 14, 2002, the complete disclosure of each of which is incorporated herein by reference.  
     [0034] According to one preferred embodiment of the invention, the heating/warming element  16  consists of die cut conductive sheet material, through which an electric current is conducted for producing local heating. The conductive sheet material may be, for example, a metallized sheet, e.g., a metallized textile or metallized plastic sheeting or a metal foil, or a conductive textile, e.g., a knitted, woven or non-woven material containing conductive fibers or yarns. The heating/warming element may be incorporated, e.g., directly or in the form of a textile laminate, into articles of clothing or footwear, and into home furnishings such as blankets and the like. Electric current, e.g. alternating current, via a power cord and plug, or direct current, via a battery, is then applied through the element to cause generation of heat, due to electric resistance.  
     [0035] Referring first to FIGS. 1 and 2, in a first embodiment, a windproof, water-resistant, and vapor permeable electric heating/warming composite fabric article  10  constructed in accordance with this invention has three major components. These components include a fabric layer  12 , a barrier layer  14  and an electric heating/warming element  16 , the fabric layer  12  and barrier layer  14  being joined at opposed fabric inner surface  13  and barrier outer surface  15 , respectively, by adhesive  18 .  
     [0036] Referring to FIG. 1A, in another embodiment the barrier layer  14  may be omitted. In this case, the electric heating/warming composite fabric article includes a fabric layer  12  and an electric heating/warming element  16 . The fabric layer  12  inner surface  13  is joined to the inner surface  17  of the electric heating/warming element  16  by adhesive  18 .  
     [0037] In both of the embodiments shown in FIGS. 1 and 1A, the fabric article  10  may further include a second fabric layer (not shown), with the heating/warming element and the barrier layer (if included) being interposed between the two fabric layers.  
     [0038] Referring to FIGS. 1, 1A, and  2 , in preferred embodiments, the fabric layer  12  is made in any well known manner, e.g. the fabric layer  12  may be a knitted material, e.g., a plaited circular knitted or reverse plaited circular knitted material, or other circular knitted material (such as double knitted, single jersey knitted, two-end fleece knitted, three-end fleece knitted, terry knitted or double loop knitted material), or warp knitted or weft knitted material, or a woven or non-woven material. In applications where the fabric layer  12  of the fabric article  10  will be directed outwardly, away from the wearer&#39;s skin, the material of the fabric layer is preferably hydrophobic, in order to resist penetration of liquids. In other applications, where the fabric layer  12  of the fabric article  10  will be directed inwardly, toward the wearer&#39;s skin, the material of the fabric layer is preferably naturally hydrophilic, chemically rendered hydrophilic, or hydrophobic, in order to enhance removal and transport of perspiration away from the skin. The inner surface  13  of fabric layer  12 , to which the adhesive  18  is adhered, is preferably flat. The exposed, outer surface  20  of fabric layer  12  may be flat or raised, e.g. by brushing, sanding or napping, and/or may be otherwise provided with decorative and functional features and finishes, e.g. as well known in the art.  
     [0039] Preferably, the barrier layer  14  is formed of a vapor permeable membrane which is nonporous hydrophilic or micro-porous hydrophobic or a combination of both, e.g. in layers, as appropriate to the nature of the intended use, or as otherwise desired. In certain embodiments, it may also be preferred that the material of the barrier layer  14  be soft and stretchable. The barrier layer is constructed and/or formulated to resist air and water droplets from passing through the composite fabric article  10  while being permeable to water vapor. In applications where it is desired that the fabric article  10  is stretchable, the fabric layer  12  may typically be a knitted material, and a preferred material for barrier layer  14  is poly urethane, e.g. as available from UCB Chemical Corp. of Drogenbos, Belgium, either micro-porous hydrophobic (preferred for use where the barrier layer  14  is directed outward) or nonporous hydrophilic (preferred for use where the barrier layer  14  is directed inward). Alternatively, in situations where relatively less stretch is required, e.g. in footwear, the fabric layer  12  may be a warp knitted material, and a preferred material for barrier layer  14  is poly tetrafluoroethylene (PTFE), e.g., as available from Tetratec, of Feasterville, Pa.  
     [0040] The barrier layer  14  is joined to the inner surface  13  of fabric layer  12  by adhesive  18 , typically applied in spots, lines or other discrete regions, or by attachment, lamination or other suitable manner of combining. A similar composite fabric (but having an additional internal fabric layer) is described in commonly assigned Lumb et al. U.S. Pat. No. 5,364,678, the entire disclosure of which is incorporated herein by reference. Referring also to FIG. 3, electric heating/warming element  16  is disposed upon the outer surface  22  of barrier layer  14 .  
     [0041] In one embodiment, the electric heating/warming element  16  is formed of metallized textile or plastic sheeting or metal foil. Suitable metallized textiles are available, e.g., from Schlegel Systems Inc. of Rochester, N.Y. The textile may be metallized by any suitable technique, e.g., by metal coating, plating, or deposition, using chemical, electrical or mechanical techniques. The metal coating or deposit is made of a conductive material that provides a very low resistance, typically less than about 500 ohms per square. Examples of suitable conductive materials include silver, copper, nickel, nickel-chrome, and combinations of these metals. The metallized textile or plastic sheeting or metal foil can be produced in any desired electrically continuous (in whole or in part) circuit pattern or produced in sheets and then diecut into the desired pattern. The element (or its parts) is then attached or inserted, e.g., alone or laminated to or between one or two layers of suitable non-conductive material, to, or into, the fabric layer  12 , to form a textile product. For a textile article in the form of a blanket, formation of the electric heating/warming element as a die cut stamping allow the buses to be formed integrally with the heating elements. The heating elements may be spaced asymmetrically so that selected regions get preferentially warmer than other regions, or, as described in more detail below, by providing selected heating elements that are relatively more narrow than other heating elements, greater resistivity, with resultant generation of more heat, can be provided to selected regions.  
     [0042] Alternatively, the heating/warming element may be formed of a conductive textile, e.g., a textile that includes conductive fibers and/or yarns. Suitable conductive fibers and yarns include, for example, carbon and polyaniline.  
     [0043] The predetermined pattern of the heating/warning element  16  may be custom designed for the particular purpose for which the composite fabric article  10  of the invention is to be used. For example, the pattern of the heating/warming element  16  of the composite fabric article  10  of FIG. 3 is designed for use in making a glove. For this purpose, the electric heating/warming element  16  forms a pattern having four elongated branches  28 A,  28 B,  28 C,  28 D (corresponding to fingers of a glove) and one or more sections  28 F (corresponding to the palm or back of the body of a glove).  
     [0044] The heating/warming element  16  is formed as a continuous circuit, terminating at each end in a contact pad  28 G,  28 H, respectively. The contact pads preferably are disposed adjacent to each other in a region convenient for connection to a source of power, e.g. for a glove, as shown, in a region to form the wrist of the glove. Still referring to FIG. 3, the heating/warming element  16  is connected, by wire conductors  30 ,  32  extending from contact pads  28 G,  28 H, respectively, in a circuit including a switch  34  and a power supply, e.g., a battery pack  36 . When switch  34  is closed, the heating/warming element  16  is activated to generate heat/warmth.  
     [0045] The pattern features of the heating/warming element  16  shown in FIG. 3 are sized and shaped to conform to the regions of the resulting fabric article, i.e., the glove, so that the composite fabric can readily be cut to form one side of a glove. Patterns for use in other types and sizes of garments and fabric articles, e.g. such as socks, sweaters, jackets, shirts, pants, hats, gloves, footwear (e.g. shoes and boots) and so on, can be generated in a similar manner, e.g., as will be discussed below with reference to FIGS.  4 - 6 .  
     [0046] Referring to FIG. 4, a composite fabric article  40  of the invention has a heating/warming element  42  sized and shaped to conform to the regions of the selected resulting fabric article, i.e., in this embodiment, a boot, to be heated/warmed so that the composite fabric can readily be cut to be formed and/or incorporated into a boot liner. In particular, the heating/warming element  42  has heating/warming regions  44 ,  45 , with sections of relatively reduced cross-sectional area for increased resistivity and heat generation, corresponding to the toe/ball and heel surfaces, respectively, of a wearer&#39;s foot. The heating/warming element  42 , which forms a circuit, terminates at each end in a contact pad  46 ,  47 , respectively. The contacts pads are disposed adjacent to each other in a region convenient for connection to a source of power, e.g., as shown, in a region to extend into or above the ankle collar of the boot.  
     [0047] Referring to FIG. 5, a composite fabric article  50  of the invention has a heating/warming element  56  sized and shaped to conform to the regions of the selected resulting fabric article, i.e., in this embodiment, the opposite chest surfaces of a garment such as a shirt or a jacket  60  (FIG. 6), to be heated/warmed. The heating/warming element  56  terminates at each end in a contact pad  58 ,  59 , respectively, the pads being disposed adjacent to each other in a region convenient for connection to a source of power, as discussed below.  
     [0048] Referring also to FIG. 6, a pair of fabric articles  50  is shown incorporated into jacket  60 . A battery pack  68  for powering each of the heating/warming composite fabric articles  50  is contained in the associated zippered pockets  70 ,  71 . The battery pack  68 , e.g. as available from Polaroid Corporation, of Cambridge, Mass., is preferably removably connected to the contact pads  58 ,  59  of heating/warming element  56  by releasable fastening elements  72 , e.g. clips, snaps or other secure but releasable fastening elements. (The fastening elements may provide the electrical connection of the battery pack to the circuit, or, alternatively, may maintain the battery pack in position for contact of the battery pack with separate connectors.) This arrangement permits the battery pack  68  to be removed, e.g., whenever the fabric article  50  is to be washed, or for replacement. The heating/warming circuit  56  may also include an oscillator chip  74  or other timing or cycling device for cycling application of electrical power from the battery pack  68  to the heating/warming element  56 , e.g., to extend battery pack life. For example, a timing cycle of three minutes “on” followed by one minute “off” is considered suitable for an electric heating/warming composite fabric article  50  incorporated as a chest panel of the heating/warm jacket  60  suited for outdoors use.  
     [0049] In one preferred embodiment, a composite fabric article  10  of the invention is formed by first combining the fabric layer  12  and barrier layer  14  with adhesive  18  disposed therebetween. An electric heating/warming element  16  is then affixed upon the surface  22  of the barrier layer  14 . The resulting composite fabric article  10  is cut to shape, and otherwise processed using standard clothing procedures, for incorporation, e.g., into an article of clothing or the like. Alternatively, the heating/warming element  16  may be affixed upon the surface  22  of the barrier layer  14 , before the barrier layer  14  and the fabric layer  12  are secured together.  
     [0050] Referring next to FIGS. 7 and 8, in another embodiment of the invention, an electric heating/warming composite fabric article  110  consists of a fabric layer  112  having an inner surface  114  upon which an electric heating/warming element  116  is disposed.  
     [0051] In embodiments of the invention where the heating/warming element  116  is affixed directly to the fabric layer  112 , the composite fabric article  110  may be employed without a barrier layer. Alternatively, a pair of fabric articles  110  may be incorporated into a garment, e.g. a jacket  60 , as shown in FIG. 6, where the outer coverings  62 ,  64  of the opposite chest surfaces of the jacket may be a shell material selected to provide a barrier layer overlaying the heating/warming composite fabric articles  110  incorporated into the jacket.  
     [0052] The relative amounts of heat/warmth generated by a region of an electrical heating/warming element in a composite heating/warming fabric article of the invention can be controlled, e.g., by varying the width and/or by varying the length and/or the thickness of a circuit element or segment, and/or by varying the conductivity/resistivity of the material forming a segment of the circuit element.  
     [0053] For example, referring to FIG. 5, a heating/warming element  56  formed of material of uniform conductivity and constant thickness has regions  80  and  82  of contrasting width, and, therefore, contrasting cross sectional area. As a result, in region  80  of relatively greater width, there is more conductivity, i.e. less resistance to current flow, and thus less generation of heat/warmth. Similarly, in region  82  of relatively lesser width, there is less conductivity, i.e. more resistance to current flow, and thus relatively greater generation of heat/warmth. As a result, a composite heating/warning fabric article  50  of the invention can be designed with a circuit element  56  that delivers relatively greater amounts of heat/warmth to selected regions of the wearer&#39;s body.  
     [0054] Alternatively, this effect may be obtained by applying a thinner layer of material, i.e., a region of relatively lesser cross sectional area. For example, referring to FIG. 9, a composite heating/warming fabric article  10 ′ of the invention has a heating/warming element  16 ′ having a region  90  of relatively lesser thickness (compared to adjacent regions).  
     [0055] Alternatively, or in addition, a heating/warming element of constant dimension but with regions generating relatively different levels of heat/warmth may be formed by sequentially applying circuit regions using materials of inherently different conductivity. For example, referring first to FIG. 10, showing a composite heating/warming fabric article  100  of the invention, a heating/warming element  102  is formed by affixing regions  104 ,  106  of a material of relatively greater conductivity, and thereafter, referring to FIG. 11, affixing region  108  of a material of relatively lower conductivity, region  108  interconnecting regions  104 ,  106 .  
     [0056] These and other methods for adjusting the conductivity of electrical circuit regions may be employed alone, or in any desired combination.  
     [0057] The conductivity of various regions of the electrical circuit may be adjusted to suit the requirements of a particular application and thereby enhance wearer comfort. For example, in the case of gloves or footwear, heating the extremities (fingers and toes) is important to providing comfort, and generally the fingers and toes, especially at their tips, require more heating than the rest of the hands and feet. Thus, it is may be desirable to generate more heat in these specific areas, which may be accomplished in any of the manners discussed above.  
     [0058] Preferred heating elements for use in gloves are shown in FIGS. 15 and 16. In both of these embodiments, the electric heating/warming element  116  forms a pattern having four elongated branches  128 A,  128 B,  128 C,  128 D (corresponding to fingers of a glove) and sections  128 E and  128 F (corresponding to the palm or back of the body of a glove). A region  129  is cut out, or is not metallized, to reduce the effective area of the conductive material. The presence of region  129  increases the resistivity of the branches  128 A- 128 D, while not significantly affecting the conductivity of the palm sections  128 E and  128 F. As a result, more heat will be generated in the branches  128 A- 128 D than in the palm sections. Additionally, within the branches  128 A- 128 D there are regions of different width. For example, in the embodiment shown in FIG. 15, the branches  128 A- 128 D include upper regions U, generally corresponding to the portion of the wearer&#39;s fingers from the first knuckle to the tip, and lower portions L, generally corresponding to the portion of the wearer&#39;s fingers from the first knuckle to the intersection of the finger with the palm. The upper regions U are narrower than the lower regions L, and thus have a greater resistivity and as a result generate more heat at the wearer&#39;s fingertips.  
     [0059] When the pattern shown in FIG. 15 is powered by 3.0 volts direct current source with an element having a resistance of 4.8 Ohms, the temperature generated in upper portions U is about 101 degrees Fahrenheit while the temperature generated in lower portions L is about 80 degrees Fahrenheit. This provides greater heat generation in the fingers, and particularly at the tips of the fingers, providing more comfort for the user while conserving battery power.  
     [0060] Similarly, in the embodiment shown in FIG. 16, the width of the branches  128 A- 128 D is further varied, to provide narrow areas  31  and  33 , generally corresponding, respectively, to the tips and first knuckles of a wearer, and wide areas  32  and  34 , generally corresponding to the areas between the knuckles of the wearer. In this example when the element is powered by a 3.0 volts direct current source with the element having a resistance of 4.8 Ohms, the temperature generated at narrow areas  31  and  33  is about 101 degrees Fahrenheit, while the temperature generated at wide areas  32  and  34  is about 80 degrees Fahrenheit. The section next to the terminals and in the palm area will have very low resistance and thus will generate very little, if any, heat. Thus, the narrow areas  31  and  33  provide high heat generation at the fingertips and close to the arteries (at the first knuckle). Providing heat generation at regions close to arteries helps to warm the blood and improve circulation. As a result, the user&#39;s fingers are kept warm without overheating the rest of the user&#39;s hand, while also conserving battery power.  
     [0061] In the embodiments shown in FIGS. 15 and 16, power is delivered to the circuit in the same manner as discussed above with reference to FIG. 3. That is, the heating/warming element  16  is formed as a continuous circuit, terminating at each end in a contact pad  128 G,  128 H, respectively, for connection to a source of power, e.g., a battery pack  136 , by wire connectors  130 ,  132 .  
     [0062] In yet another embodiment of the invention, the electric heating/warming composite fabric article  110  described above with reference to FIGS. 5 and 6 may be further processed. For example, referring now to FIGS. 12, 13 and  14 , in an electric heating/warming composite fabric article  120 , a barrier layer  122 , e.g. as described above, is attached adjacent to the side of the inner surface  114  of the fabric layer, overlying at least a portion of the heating/warming element  116 , using adhesive, also as described above. Preferably, contact pads  118  (only one is shown) of heating/warming element  116  are left exposed for connection to a source of power (FIG. 13), or electrical connectors  124  (only one is shown) are provided for connecting the contact pads and power source through the barrier layer  122  (FIG. 14).  
     [0063] In all cases described above, the heating/warming element is supported by a fabric layer, whether or not a barrier layer is provided. The fabric layer may be naturally hydrophilic, chemically rendered hydrophilic, or hydrophobic. In some preferred embodiments, a barrier layer is provided at least adjacent to the inner surface of the fabric layer, i.e., attached to the fabric layer (with or without intervening materials) or spaced from attachment to or upon the fabric layer, but positioned at the inner surface side of the fabric.  
     [0064] A barrier layer associated with or attached, e.g. by lamination or other techniques, upon the surface of the fabric layer  12  upon which the heating/warming element  16  is affixed (e.g. barrier layers  62 ,  64 ; FIG. 6 and barrier layer  122 ; FIGS.  12 - 14 , respectively) serves also to protect the circuit against the effects of abrasion that might otherwise deteriorate the quality or continuity of the electrical heating circuit. The barrier layer would also serve to resist short-circuiting in the event that condensate forms on the fabric layer inner surface. The barrier layer may be formed of any suitable, protective material. It will preferably be micro porous hydrophobic or nonporous hydrophilic if it is a complete layer. Where a complete layer is not desired or employed, the barrier layer may be applied exclusively to the printed circuit itself, in which case, it will preferably be nonporous hydrophobic.  
     [0065] If desired, the temperature of a portion of the heating/warning element can be measured during use. For instance, a sensor can be included to determine the temperature at the fingertip of the glove. The sensor can be placed at the fingertip, with a wire running down the finger. However, this may interfere with dexterity, and thus it may be desirable to simulate the fingertip temperature at another area of the glove and measure the temperature at that area. For example, in the heating/warming element  148  shown in FIG. 17, the temperature at fingertip  150  can be simulated by providing two cut-out areas  152  in the palm region, near the wire conductors  154 ,  156 , that define a rectangular area  158  that is calculated to have the same resistance as the portion of the circuit in the fingertip  150 . Thus, the temperature at the fingertip can be estimated remotely by measuring the temperature of the area  158 . This temperature data can be used, in conjunction with a controller (not shown), e.g., a voltage regulator, to automatically shut off the battery or deliver less power to the circuit when a maximum temperature is detected, and turn on the battery or increase power delivery when a minimum temperature is detected. Alternatively, or in addition, the temperature can be displayed on a read-out (not shown) mounted on the glove, and a manual control can be provided to allow the wearer to turn the battery on and off or adjust the temperature.  
     [0066] A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention.  
     [0067] For example, additional fabric layers may be added to enhance various aesthetic and functional characteristics of the electric heating/warming composite fabric article.  
     [0068] Moreover, while the circuits in the embodiments discussed above have been series circuits, the circuit used in the heating/warming element may be a parallel circuit, e.g., as shown in FIG. 18. In the heating/warming element  200 , shown in FIG. 18, the relatively wide areas  202  act as buses, while the cut-out areas  204 ,  206  provide areas of higher resistivity, as discussed above. The circuit shown in FIG. 18 also illustrates that the circuit need not be symmetrical, e.g., in the circuit shown in FIG. 18 there are three cut-out areas  206  in the upper region of the circuit, but only two cut-out areas  204  in the lower region of the circuit.  
     [0069] Further, while circuits for gloves have been described above, by way of example, the heating/warming element may be used in many different applications. For example, a heating/warming element  220 , for use in a sock, shoe, or other article of footwear, is shown in FIG. 19. In the heating/warming element  220 , the circuit includes a left hand portion  222  and a right hand portion  224 , separated by a cut-out area  226 . Cut-out area  226  is shaped to provide relatively wide bus areas  228  in the heel region, and relatively narrower, higher resistivity areas  230  in the forefoot region. The toe portions  232  are narrowest of all, and thus have the highest resistivity, so that the highest temperature will be generated adjacent the wearer&#39;s toes.  
     [0070] Accordingly, other embodiments are within the scope of the invention.