Abstract: A heating element assembly in the form of a heating shelf and a method of manufacturing heating shelf assemblies. The heating shelf may be used in display cabinets to heat ready made foods such as cookies, muffins, donuts, pizza, sandwiches and the like. The preferred heating shelf includes thermochromic materials, or an LED indicator, which provide a visual indica of shelf temperature. The preferred heating shelf provides intimate contact with the heated food products, thus optimizing heat transfer between the heating shelf and the food products. Optionally provided, varied surface watt density in the heating shelf allows for accurate heat placement such that the food products can be evenly warmed while avoiding over warming. In another embodiment, the heating shelf includes two resistance heating elements. The first heating element is a temperature booster used for defrosting and heating, while the second heating element is a maintenance heater to maintain heated food at a serving temperature.

Abstract: A heated container is formed from a substantially continuous element structure. The substantially continuous element structure includes an electrically insulative first and second polymeric layers and a resistance heating layer laminated between the first and second polymeric layers. An interior surface of the container includes the first polymeric layer, and the first polymeric layer is thermally conductive. The resistance heating layer has a pair of terminal end portions that may be coupled to a pair of external power leads to energize the resistance heating layer.

Abstract: A soft heater, containing metal, carbon or conductive ink coated textile threads, embroidered on, laminated between or woven into a nonconductive substrate to form electrical heating circuits. The heating element may be manufactured in a form of strip, sheet, sleeve or strand of electrically conductive threads for incorporation into plurality of articles. The heating element is shaped or embroidered in a desired pattern. The embroidered heater may be used for a night vision identification purposes.

Abstract: A heating element assembly in the form of a heating tray and a method of manufacturing heating tray assemblies. The heating tray may be used for defrosting and heating pans such as so-called “half-pans” of frozen food products. The preferred heating tray is configured to fit precisely around a standard thin foil half-pan container, thus optimizing heat transfer between the heating tray and the food product. The varied surface watt density of the heating tray allows for accurate heat placement such that the food product can be evenly warmed while avoiding over warming or burning, particularly at the corners and edges. A preferred embodiment of the heating tray includes two resistance heating elements. The first heating element is a temperature booster used for defrosting and heating, while the second heating element is a maintenance heater to maintain heated food at a serving temperature.

Abstract: A wall-mounted cabinet having a pivotable door with opposed exterior and interior mirrors which can be convectively and radiatively heated to prevent fogging, by a sheet heater between the two mirrors. The exterior mirror is electrically insulated, and the exterior and interior mirrors are grounded to prevent electric shock.

Abstract: An electric heating device includes a flexible resistor ribbon, a plurality of sections of electroconductive coating attached to the resistor ribbon at preset intervals, and connector contacts coupled to the resistor ribbon for enabling connection of a power source to the resistor ribbon. The resistor ribbon has a high specific impedance. The flexible resistor ribbon is attached to a rigid or flexible flat base panel for incorporation into a building as a floor, wall or ceiling panel. Layers of electric insulation are attached to the base so as to sandwich the flexible resistor ribbon. Where the resistor ribbon is bent back on itself, for example, to form a snaking configuration, a strip of two-sided adhesive tape is attached to the layers of electric insulation and to the ribbon at multiple spaced points.

Abstract: An expandable chamber support system for vehicle seat and mattress applications includes an expandable chamber constructed from facing sheets of flexible impermeable material that are sealed along their marginal edges. An upper one of the sheets is formed of electrically conductive elastomeric membrane that is electrically resistance heated while cooperating with a lower one of the sheets to provide pressure support for an occupant supported by the expandable chamber.

Abstract: A decorative heating pad assembly (10) is provided which includes a main body (12) in the form of a stylized mock animal such as a manatee. The assembly (10) has stitched-together top and bottom walls (24, 26) with soft, pliable fill (29), and presents a trunk or primary section (18) together with appendages such as head (20) and flippers (22). A fabric panel (14) is secured to the bottom wall (26) to form a pocket (44) adapted to receive a heating pad (46). The pocket (44) is configured so that a user's hand and forearm (A) can be inserted within the pocket (44) between the pad (46) and bottom wall (26). A variety of stylized animal configurations can be used, such as a manatee, turtle, bear, beaver, dog and cat.

Abstract: A heated tire for melting snow and ice that contacts a vehicle's tire tread. The heated tire includes a vehicle tire that has a heating apparatus integrally formed within the tire between the tire tread and the outermost steel belt and is automatically activated by a control unit interlinked to a temperature sensor.

Abstract: This invention is a flexible heater or cooler which includes a flexible, conformal, thermally conductive container filled with thermally conductive material. A thermal element within the container or in contact with the outside of the container provides heat to the container or removes heat from the container. The thermal element is powered by a low voltage direct current electrical source. A sensor for determining the temperature of the thermally conductive material is also included. The thermal element, electrical source, and sensor are in communication by connectors with a solid state continuous temperature controller. In operation, the electrical source provides power to the thermal element, thereby heating or cooling the thermally conductive material within the container. The temperature in the container is determined by the sensor and the controller controls the power delivery to the thermal element in response to the setting on the controller and the temperature in the container.

Abstract: A dissolution testing system comprises a vessel plate on which a plurality of vessels are mounted. Each vessel includes a lateral wall having an outer surface around which a plurality of flexible heater elements are attached. Each heater element includes a transparent surface area, a heat conductive element extending along the transparent surface area, a temperature sensing element extending along the transparent surface area, and an electrical contact element connected to the heat conductive element and the temperature sensing element. The heater element can have more than one heating zone, with at least one of the heating zones being selectively energizable. The transparent heater element allows unobstructed view into the interior of its vessel, and reduces the time required to achieve a stabilized set point temperature in the vessel. A heater control system communicates with each heat conductive element and each temperature sensing element through a corresponding one of the electrical contact elements.

Abstract: A heater cable is wired in combination with a lead cable, the two cables are formed such a pattern that the heater cable and the lead cable are spaced by a predetermined distance L from each other and are capable to be supplied with opposite flows of current. The heater cable has a core thread, a heating element wire wound in a spiral on the outer surface of the core thread, a fusing layer provided over the heating element wire, a signal wire wound in a spiral on the outer surface of the fusing layer and a protective coating provided over the signal wire. The lead cable has a conductive wire covered at its outer surface with an insulating coating.

Abstract: A disposable blanket for one-time patient use for warming a patient includes a heating matrix associated with a sheet of plastic film and a circuit printed on one side of the sheet of plastic film, a cover, and a connecting mechanism for connecting the heating matrix with a power source. The power source for the blanket can be supplied by rechargeable batteries, a wall outlet, or a cigarette lighter. The blanket is thrown away after use.

Abstract: A heat generating medium for image fixing includes a conductive support layer of good electrical and thermal conductivity, a low surface energy layer formed on one of the surfaces of the conductive support layer, and a heat generating layer formed on the other surface of the conductive support layer. A fixing apparatus is also disclosed, which includes the heat generating medium as described above, and a power supplying device for feeding current to the heat generating layer, wherein a recording sheet bearing a non-fixed toner image thereon is brought into press contact with the heat generating layer which generates heat when it receives current from the power supply device.

Abstract: The invention relates to a heating element for a part of an automobile which is held, especially the steering wheel. The heating element consists of a textile support with at least one heating resistor. According to the invention, a knitted textile support is used.

Abstract: A method for the transport of liquid in a textile or porous structure, whereby the liquid is forced to travel through the textile with the aid of electric pulses applied to a conductor or semi-conductor which is woven onto, or in some other fashion applied to, each side of the material which may be a single textile or several layers of textiles which together form a laminate.

Abstract: A system and apparatus for and method of fusing a wrap to a portion of a length of plastic-coated pipe are disclosed. The system comprises a thermoplastic piece shaped to conform to the portion of pipe, the piece including a heat-generating trace and the heat-generating trace including a plurality of trace leads thereon. The system further comprises a clamp for applying pressure to the piece in the vicinity of the heat-generating trace, the clamp including at least two compression bands, each of the compression bands including a plurality of power leads, each of the power leads corresponding to one of the trace leads. The power leads preferably automatically are placed into electrical contact with said trace leads when the clamp is applied over the thermoplastic piece.

Abstract: A defrosting assembly for a mirror of a vehicle for keeping sideview mirrors free of ice. The defrosting assembly for a mirror of a vehicle includes a transparent planar sheet and an electrical wire. The electrical wire has a medial portion that is coupled to the transparent planar sheet. An adhesive is coupled to a face of the planar sheet. The adhesive may be coupled to the mirror of the vehicle thereby coupling the planer sheet and medial portion of the electrical wire to the mirror. The electrical wire is designed to couple to a battery of the vehicle thereby creating an electrical current through the electrical wire. The electrical current passing through the electrical wire heats the electrical wire. The heating of the electrical wire defrosts the mirror.

Abstract: A fabric article that generates heat upon application of electrical power is formed, for example, by knitting or weaving, to form a fabric prebody. An electrical resistance heating element in the form of a conductive yarn is incorporated into the fabric prebody, the electrical resistance heating elements extending between opposite edge regions of the fabric. Conductive elements are provided for connecting the electrical resistance heating elements to a source of electrical power.

Abstract: An electrical heating pad for use with an ungrounded source voltage comprises a heating element arranged in the heating pad and defining a substantially coplanar plane and a fabric outer cover co-planarly enclosing the heating element. The heating element includes a first core made of an insulating material; a first conductive element wound around the first core using the first core as an axis; a second core made of an insulating material arranged in surrounding relation to the first core and the first conductive element; and a second conductive element wound around the second core using the second core as an axis. The first and second conductive elements are connected to each other at one ends and are connected to the ungrounded source voltage at the other ends to at least partially cancel out magnetic field generated from each conductive element. There is at least one shield layer located at one side of the coplanar plane defined by the heating element for substantially shielding electric field.

Abstract: A soft heating element, utilizing electro conductive textile threads as a heating means having additional safety functions as TCO (thermal cut-off) and TSL (temperature self-limiting) devices. The thermal cut-off function is achieved through melting of the electro conductive threads at the temperatures above 120° C. and below 350° C., which results in termination of electrical continuity in the heating element. The temperature self-limiting capability is achieved through a heating thread electrical resistance increase during slow elevation in its temperature, which is below its melting point. Methods of electrical and mechanical connection between heating threads and metal conductors, utilizing winding of connections with flexible strands of fibers or wires, with optional subsequent placement of a rigid mechanical fastener over the winding.

Abstract: A reticulate heater has a net-mesh-like-structured heat generator 2 including a plurality of heater wires 20 each having the same wire diameter of from 0.02 to 0.12 mm. The plurality of heater wires 20 are formed into the net-mesh-like-structured heat generator 2 by a tricot knitting technique wherein loops are vertically formed by vertically knitting the heater wire on a continuous and planar basis. The knit meshes of the tricot knitting each have a pitch of 0.5 to 5 mm. Also, the heater wires may be the ones prepared by covering the heater bare wires with a for-enamel-wire coating. Further, the net-mesh-like-structured heat generator 2 may be the one including a plurality of first heater wires each consisting of a heater bare wire only and a plurality of second heater wires each prepared by covering the heater bare wire with a for-enamel-wire coating, the first and second heater wires being formed into the net-mesh-like-structured heat generator by a tricot knitting technique.

Abstract: A fibrous article that generates heat upon application of electrical power is formed, for example, by joining stitch and loop yarns to form a fibrous prebody, with the loop yarn overlaying the stitch yarn at a technical face and forming loops at a technical back of the fabric prebody. An electrical resistance heating element, e.g., in the form of conductive elements, is joined with the stitch and loop yarns in the prebody at symmetrical and/or asymmetrical spaced-apart intervals as the stitch yarn, the electrical resistance heating elements extending between opposite edge regions of the fibrous article and conductor elements, e.g. located along edge regions, connect the electrical resistance heating elements to a source of electrical power. The technical face and/or the technical back of the fabric body may have fleece formed by finishing non-conductive fibers of the stitch yarn and/or loop yarn in a manner to avoid damage to electrical conductance of the electrical resistance heating elements.

Abstract: A fabric article that generates heat upon application of electrical power is formed, for example, by joining stitch and loop yarns to form a fabric prebody, with the loop yarn overlaying the stitch yarn at a technical face and forming loops at a technical back of the fabric prebody. An electrical resistance heating element, e.g., in the form of a conductive yarn, is incorporated into the fabric prebody at symmetrical and/or asymmetrical spaced-apart intervals as the stitch yarn, the electrical resistance heating elements extending between opposite edge regions of the fabric and conductor elements, e.g. located along edge regions, connect the electrical resistance heating elements to a source of electrical power. The technical face and/or the technical back of the fabric body may have fleece formed by finishing in a manner to avoid damage to electrical conductance of the electrical resistance heating elements.

Abstract: A lagging device, comprises a flexible and insulating pad; anode plate and cathode plate arranged in parallel on the top surface of the pad; a plurality of PTC ceramic resistor arranged cross the anode plate and the cathode plate. Each resistor has anode and cathode in contact with the anode plate and the cathode plate, respectively. The lagging device further has an isolation layer covering at least the topside of the pad. The inventive lagging device can be easily applied to curve surface.

Abstract: This modular snow melting carpet device for melting snow and ice on pathways comprises a flat sheet of generally rectangular shape, two conducting wires embedded in the sheet and running along the length of the sheet and generally close to their respective length edge. The conducting wires are connected at both of their extremities to a female single pin connector also embedded into the sheet and exposed at the width edges. The device also comprises a plurality of heating elements also embedded into the sheet and parallel connected along said conducting wires and, two male single pin connectors adapted to mate with the female connectors of one edge and connected to a power source. Additionally, an intersection device may comprise two crossover connecting wires embedded into the sheet and electrically insulated from the conducting wires and heating elements.

Abstract: A removable cloth sleeve with incorporated heating coil including a heating element wrappedly engaging a bottle of lotion. The heating element is comprised of an interior heating pad. The interior heating pad has an innermost heating coil. The heating element includes an outer cloth pad for removably receiving the interior heating pad therein. The heating element can be removably coupled with the bottle of lotion.

Abstract: A distributed activation system for a unitary sheet of electrically conductive or insulative shape memory alloy having a sufficiently small section to limit the lateral flow of heat including at least one heating element disposed on the shape memory alloy sheet for locally heating an adjacent portion of the sheet such that the adjacent portion assumes a predetermined shape when activated to its threshold temperature. The activation system may be configured for shape memory alloy apparatus and related methods in combination with a control system for selectively activating discrete-shape memory alloy portions with various combinations of at least one heating element that receive an adjustable current such that the resultant local heating causes the sheet to assume a desired overall shape. Methods of forming and selectively activating two-dimensional sheets of electrically conducive and insulative shape memory alloy are further provided.

Abstract: Heating elements, electrical devices and processes for manufacturing these components are provided. The heating elements and electrical components employ a fibrous support layer, such as a non-woven glass mat, which provides structural support to the relatively thin cross-section of the electrical device or resistance wire when a polymeric layer is applied.

Abstract: Electric resistance heating/warming composite fabric articles have a fabric layer having a first surface and an opposite, second surface, and an electric resistance heating/warming element in the form of a conductive yarn mounted upon first surface of the fabric layer, e.g. in embroidery stitching, and adapted to generate heating/warming when connected to a power source. A barrier layer may be positioned, for example, at least adjacent to the first or second surface of the fabric layer. Methods of forming electric resistance heating/warming composite fabric articles are also described.

Abstract: A fabric disk to protect the flavor coffee or tea from excess heating comprising heat resistant fibers.

Abstract: A soft heater utilizing metal, carbon or conductive ink coated threads, embroidered on, laminated between or woven into a nonconductive substrate to form electrical heating circuits. The heating element may be manufactured in a form of strip, sheet, sleeve or strand of threads for incorporation into plurality of articles. The soft heating element core may contain localized treatment such as positive temperature coefficient (PTC) material for temperature self-limiting control. The electrode conductors are attached to said heating element core which is connected in parallel or in series. The heating element core is shaped in a desired pattern. The whole assembly is sealed by at least one electrically insulated layer which envelopes the strips, sheets, sleeves, ropes or strands of threads.

Abstract: A soft heater utilizing metal fiber containing, carbon, metal or conductive ink coated threads, embroidered on, laminated between or woven into a nonconductive substrate to form electrical heating circuits. The heating element may be manufactured in a form of strip, sheet, sleeve or strand of threads for incorporation into plurality of articles. The soft heating element core may contain localized treatment such as positive temperature coefficient (PTC) material for temperature self-limiting control. The electrode conductors are attached to said heating element core which is connected in parallel or in series. The heating element core is shaped in a desired pattern. The whole assembly is sealed by at least one electrically insulated layer which envelopes the strips, sheets, sleeves, ropes or strands of threads.

Abstract: A heated container for transport of prepared hot food has a combination of an electric heating element with an insulation layer comprising metal foil layers and fiber layers. The combination of metal foil layers, which spread the heat from the heating element, and the fiber insulation layers provides an efficient food transport container having sufficiently low power requirements to enable powering the heater element from an automotive 12 volt system while maintaining a food temperature inside the container at about 150° F.

Abstract: An ice and snow melting system includes at least one sensor configured for sensing a temperature or moisture associated with an ambient environment and providing a signal indicative thereof. A heater for melting the ice and snow includes a heater wire, a layer of insulation substantially surrounding the heater wire, and a conductive shield substantially surrounding the layer of insulation. A ground fault circuit interrupter is coupled with the shield of the heater. The ground fault circuit interrupter detects a ground fault condition between the heater wire and the conductive shield and provides a signal indicative thereof. An automatic controller is connected to the at least one sensor. The controller includes heater control circuitry receiving each of the sensor signal and the ground fault circuit interrupter signal. The heater control circuitry selectively controls operation of the heater dependent upon the sensor signal and the ground fault circuit interrupter signal.

Abstract: A fabric article that generates heat upon application of electrical power is formed, for example, by knitting or weaving, to form a fabric prebody. An electrical resistance heating element in the form of a conductive yarn is incorporated into the fabric prebody, the electrical resistance heating elements extending between opposite edge regions of the fabric. Conductive elements are provided for connecting the electrical resistance heating elements to a source of electrical power.

Abstract: An ice prevention mat system that includes multiple resilient electrically heatable mats that are positionable to cover a desired pathway and which includes a control circuit for maintaining each of the electrically heatable mats at a temperature sufficient to melt snow falling on the mat as well as to prevent the formation of ice on the mat top surface. Each of the multiple resilient electrically heatable mats has a top surface partially covered a non skid or slip coating as well as light assemblies along the side borders to clearly identify the side edges of the mats.

Abstract: A form fitting heating surface for children's safety car seats having a contoured deformable apertured shape that is adaptable within a car seat on which the child is positioned. The heating surface is electrically connected to the automobile's power supply and is thermostatically controlled. Attachment elements adjustably extend from the heating surface for engagement over a portion of the car seat holding the heating surface insert in place within.

Abstract: A conductive element useable as a resistance heater comprises a carbonized fabric (12) which has electrical terminals (18, 20) connected thereto and is encapsulated in or sandwiched between layers of plastic insulating material. The element generally is flexible and can be embodied in for example blankets for animals, vehicle seats and clothing. It is preferably provided with an electrical control circuit for controlling the temperature to which the fabric heats.

Abstract: A shape memory device includes a shape memory alloy member configured to have at least a portion of the shape memory alloy member be selectively activated. A heating device is coupled to the member and configured to provide heat to a selected section of the member and activate at least a portion of the selected section.

Abstract: An ice shield for use with an eave of a roof, the roof including a gutter assembly secured in proximity to a downwardly angled and terminating edge of the eave. The shield includes at least one continuously wound roll of a flexible and elongate mat of material which includes a first exposed face and a second reverse side face. The elongate mat is preferably constructed of first and second layers of a durable and rubberized material, capable of convecting heat generated by generally longitudinally extending coils embedded between the layers. The mat is unrolled and positioned atop and along an eave edge location of the roof. An adhesive coating of specified width is applied in longitudinal fashion along the reverse side face and a release tape is applied over the coating to prevent bonding of concentrically wound layers of the roll and prior to a selected length of the roll being unrolled and positioned.

Abstract: A low profile heater for plastic injection molding equipment nozzles utilizes forces provided to the axially ends of a tube portion to radially compress the tube portion onto a coiled heater element thereby compressing the heater element radially inward for optimal heat conduction between said heater element and the nozzle onto which the heater is attached. Further embodiments uses a base sleeve onto which the coiled heater element is placed to engage the nozzle. The base sleeve may utilize a tapered threaded portion with slits in the sleeve to allow tightening of a ring portion to radially compress the sleeve base onto the nozzle.

Abstract: A fabric article that generates heat upon application of electrical power is formed, for example, by joining stitch and loop yarns to form a fabric prebody, with the loop yarn forming in loops that overlay the stitch yarn at the technical face form the technical and back of the fabric prebody. An electrical resistance heating element in the form of a conductive yarn is incorporated into the fabric prebody at symmetrical and/or asymmetrical spaced-apart intervals e.g., as the stitch yarn, the electrical resistance heating elements extending between opposite edge regions of the fabric. The technical face and/or the technical back of the fabric body is finished, in a manner avoiding damage to electrical conductivity of the electrical resistance heating elements, to form a fleece surface region, and conductive elements are provided for connecting the electrical resistance heating elements to a source of electrical power.

Abstract: An electric blanket used with a source voltage has a control device connected to the source voltage to control the source voltage in response to a predetermined temperature setting and a heating pad having a heating element arranged in the heating pad and connected to the output of the control device to generate heat. The heating element includes a first core, a first conductive element spirally wound around the first core, a second core arranged in surrounding relation to the first core and the first conductive element and a second conductive element spirally wound around the second core. The first ends of the first and second conductive elements are connected to the output of the control device and the second ends are connected to each other to define a conductive loop. The heating element further comprises an outer cover that covers the second core and the second conductive element and shields the internal components from external environment.

Abstract: The seat heater includes at least one electric sheet-type heating element (10) made of flexible high-resistivity material to which the main electrodes (13A, 13B) are connected. In order to minimize the time during which the seat is perceived as being cold without any notable increase in overall power requirements, the seat heater is equipped with an additional feature (18A, 18B) for heating basically at least a partial area (SH) of the sheet-type heating element (10) with increased heating density, and a switch device for changing from heating the partial area (SH) with the additional feature (18A, 18B) to overall homogeneous heating of the sheet-type heating element (10) with regular heating density through the main electrodes (13A, 13) or the main electrodes (13A, 13B) and the additional feature (18A, 18B).

Abstract: The invention relates to heatable wind energy turbine blades and to a method of heating and deicing the turbine blades using conductive fabrics to displace and/or cease the buildup of ice on the turbine blades by electrothermal fabric heater disposed or integrated on the turbines for effectively deicing the blades. Multiple turbine blade design methods are explored as well as heater materials and the application of such materials.

Abstract: Electric heating/warming composite fabric articles have at least a fabric layer having inner and outer surfaces, and an electric heating/warming element in the form of a flexible, preferably stretchable, electricity-conducting film disposed at the inner surface of the fabric layer and adapted to generate heating/warming when connected to a power source. A barrier layer may be positioned, for example, adjacent to the inner surface of the fabric layer; e.g., with the electric heating/warming element formed thereupon. Methods of forming electric heating/warming composite fabric articles are also described.

Abstract: An elongate heater (1) in which a resistive heating element core is surrounded by a first insulating jacket (9) and a second insulating jacket (11). In a preferred embodiment the resistive heating element core comprises a conductive polymer composition (3) and the heater passes the VW-1 flame test. The second insulating jacket (11) may be made from the same material as the first insulating jacket (9). For some applications it is preferred that the second insulating jacket be a thin film, e.g. polyester film.

Abstract: A reflector assembly in a satellite system includes a reflector having a reflecting surface. At least one sensor is configured for sensing a temperature of the reflecting surface or moisture associated with the reflecting surface. Each sensor is configured to provide a signal indicative of the sensing. A heater is configured for heating the reflecting surface. The heater includes a heater wire, a layer of insulation substantially surrounding the heater wire, and a conductive shield substantially surrounding the layer of insulation. A ground fault circuit interrupter is coupled with the shield of the heater. The ground fault circuit interrupter is configured for detecting a ground fault condition between the heater wire and the conductive shield and providing a signal indicative thereof. An automatic controller is connected to the at least one sensor. The controller includes heater control circuitry receiving each of the sensor signal and the ground fault circuit interrupter signal.

Abstract: A heating assembly, for use as an electric blanket or personal heating pad, includes a flexible heating panel and an electric circuit for heating the panel. An electrical heating element is mounted directly on the panel and includes inner and outer coaxial coil conductors separated by an electrically insulating layer and surrounded by an outer electrically insulating layer. A two-core flexible electric cable connects the heating element to the power supply, and to an electric control switch for controlling operation of the heating element, a fuse being located in the circuit to be actuated in the event of a short circuit occurring between the conductors of the heating element, due to breakdown of the inner insulating layer. The electric circuit also includes a device for controlling the temperature of the heating element.