Abstract: A heated pipe assembly, particularly useful with plastic pipe, which comprises a pipe having an electrically insulating, longitudinally-extending outer surface, a pair of conductors extending longitudinally of the outer surface generally parallel to and spaced from each other, an organic plastic sheet wrapped circumferentially around the outer surface of the pipe, and a semi-conductor pattern carried on a radially-facing surface of the sheet. The semi-conductor pattern comprises a plurality of generally axially-spaced semi-conductor strips and, between adjacent strips, a portion of the plastic sheet that is free from the semi-conductor pattern. The stripes are on the same side of the sheet as the conductors, and each stripe is in electrical contact with both conductors.

Abstract: A heat tracing tape which can be cut to required lengths has a heating element comprising at least two lengths of woven or braided resistance wire each in the form of a flat strip. The strips are encased in extruded silicone rubber whereby they are spaced from one another. The strips are electrically connected at one end by a connector and the tape is provided with a power supply termination either at its other end, or at a T-branch connection, for connecting the tape to the power control system. The power control system is adjustable to set an estimated value of power required to maintain a predetermined process temperature. The system automatically adjusts the power supplied to the tape to the estimated value by means of a feedback control system. A process temperature sensor also regulates the power supplied to the tape in accordance with a sense temperature.

Abstract: A heating sheet is provided in which protective covers are laminated to both surfaces of a heating element in which plastic sheets are respectively formed on the two surfaces of a metal foil heating circuit. The protective covers are adhered to the heater element such that indentations or recesses may be formed in those portions of the protective covers which do not correspond to the heating circuit.

Abstract: System and method for producing a composite, particularly applicable for repairing damage to a structural component, wherein an electrical resistance heating element basically in the form of a layer of conductive carbon or graphite, e.g., in fiber form, becomes bonded to and forms a part of the cured composite. In the repair of a parent structure, a patch comprising a heat curable resinous material is applied to the parent structure, and a heat bondable adhesive film is positioned between the parent structure and the patch. An electrical resistance heating element in the form of a layer of graphite fibers is provided in contact with, or forming a part of, the patch, the heating element being capable of bonding the patch to the parent structure upon heating the adhesive bond to a predetermined temperature, to form a unitary structure comprised of the damaged parent structure, the patch and the heating element.

Abstract: Laminar heaters comprise a laminar heating element sandwiched between two laminar electrodes having substantial electrical resistance along the thickness thereof. The heater has a heating area of irregular shape, and at least one of the electrodes extends over a connection area in which heat is not generated but which provides a shorter and/or more uniform current path to the heat-generating parts of the heater.

Abstract: A PTC heater assembly comprises at least one PTC heater surrounded by an envelope of high thermal conductivity, thus greatly increasing the power output of the heater under operating conditions. In a preferred assembly a strip heater, comprising (i) an elongate strip of a conductive polymer PTC composition, (ii) electrodes embedded in said strip, and (iii) an insulating jacket, is sandwiched between a pair of metal, e.g. aluminum, sheets.

Abstract: A sheet heater including a substrate, a semi-conductor pattern (typically of colloidal graphite) having a pair of parallel, spaced-apart, longitudinally-extending stripes and a central portion extending between and electrically connected to the stripes, and a pair of parallel, spaced-apart, longitudinally-extending conductors one of which overlies and engages each of the stripes. Each conductor is significantly wider than the underlying stripe of the semi-conductor pattern, and includes a longitudinally extending strip portions along the inner and outer edges of the conductor, and a plurality of longitudinally-spaced openings located therebetween. The strip portion at the inner edge of the conductor overlies and engages a respective stripe; and a sealing layer of insulating material overlies the respective conductor and is sealed to the substrate along the inner and outer edges of the conductor and through the longitudinally spaced openings.

Abstract: An electrical heating fabric has a warp composed of non-conductive threads, and selvedges which include plural lead wires. In the weft direction the fabric has both non-conductive threads and conductive wires. The different types of weft material are arranged in successive strips disposed transversely to the warp. First strips have non-conductive weft threads only. Second strips additionally have conductive weft wires. The strips are arranged alternately. The weft wires are all discrete, and their two ends are either in simple contact with the selvedge lead wires or are interwoven therewith.

Abstract: A steering wheel having cross spokes and mounted for rotation on a steering column is provided with an electric heating arrangement including a thin strip of metal foil adhesively bonded to and extending substantially about the entire outer periphery of the wheel. The outer surface of the foil strip is coated with an electrically insulating plastic film and a protective cover is disposed over the foil strip and steering wheel outer periphery and secured by lacing. A control switch mounted on one of the spokes is connected to the foil strip by power supply leads extending along the spoke. A current limiting resistance element is interposed intermediate the length of the metal foil strip to insure moderate current levels therethrough and is carried by another spoke of the wheel.

Abstract: An electrical heating device comprises a substrate, an elongated conductor extending longitudinally of the substrate, a semi-conductor pattern carried on the substrate and electrically connected to and extending from the conductor pair, and a sealing layer overlying the conductor and sealed to the substrate at opposite sides of the conductor. The conductor comprises a pair of rectangular in cross-section metallic conductor elements, placed one on top of the other in face-to-face engagement with and unattached to each other. The bottom conductor elements faces towards the substrate and the upper conductor elements faces towards and engaging the sealing layer.

Abstract: A planar heating element having a positive temperature coefficient has a plurality of spaced electric current supply lines constituted by contact bands and a planar support, the electric current supply lines being operatively connected to the planar support, the contact bands and the support including an electrically conductive synthetic resin whose electrical resistance has a positive temperature coefficient.

Abstract: Laminar heaters comprise a laminar heating element sandwiched between two laminar electrodes having substantial electrical resistance along the thickness thereof. The heater has a heating area of irregular shape, and at least one of the electrodes extends over a connection area in which heat is not generated but which provides a shorter and/or more uniform current path to the heat-generating parts of the heater.

Abstract: Electrical resistance heating element including a number of metal strips arranged in a meander-like pattern. In the resistance metal strips, which are made from a non-expensive base sheet material like lead, there is incorporated at least one fuse which will operate if the heat transfer from a randomly placed area of critical size (a critical area) is substantially blocked. The fuse or fuses are preferably constituted by a lead/tin alloy rolled into intimate contact with the lead base material.

Abstract: The heater of the present invention includes a paper or plastic substrate on which is printed a semi-conductor pattern (typically a colloidal graphite ink) having (a) a pair of longitudinal stripes extending parallel to and spaced apart from each other and (b) a plurality of identical bars spaced apart from each other and extending between and electrically connected to the stripes. A metallic conductor (typically copper stripping) overlies each of the longitudinal stripes in face-to-face engagement therewith, and the conductors are held in tight engagement with the stripes by a sealing layer that overlies the metallic conductors and is sealed, at opposite sides of the semi-conductor stripe associated with the particular metallic conductor, to portions of the substrate that are free from the printed semi-conductor pattern.

Abstract: A PTC heater assembly comprises at least one PTC heater surrounded by an envelope of high thermal conductivity, thus greatly increasing the power output of the heater under operating conditions. In a preferred assembly a strip heater, comprising (i) an elongate strip of a conductive polymer PTC composition, (ii) electrodes embedded in said strip, and (iii) an insulating jacket, is sandwiched between a pair of metal, e.g. aluminum, sheets.

Abstract: Articles which are heat-recoverable, or which can be rendered heat-recoverable or which have been heat-recovered, comprise a member composed of a conductive polymer and, attached to said member, at least two electrodes, at least one of which is an electrode comprising a plurality of pliable conductive elements, e.g., a braided tube. By connecting the electrodes to a source of electrical power, current is caused to pass through and heat the conductive polymer member. The heat generated can be used to provide all or part of the heat necessary to cause recovery of the heat-recoverable article. The conductive polymer preferably exhibits PTC behavior, thereby regulating the maximum temperature to which the article can be heated.

Abstract: Electrical resistance strip heating element, the insulated side areas of which are mechanically reinforced in order to render the strip less sensitive to tearing. The reinforcement may be of a slightly stretchable open mask type textile web.

Abstract: The present invention relates to a heating element usable in particular in aquaria, characterized in that it is constituted by an electrical element proper, coated with a moldable and waterproof heat-conducting material, such as a resin preferably, which can be shaped by known methods.

Abstract: A flexible heating element comprises at least two flexible electrical conductors spaced apart by a PTC material, an amorphous highly conductive rubber compatible with the PTC material and adhered to each conductor being interposed between the PTC material and each conductor whereby in use current passes from one conductor to another through the PTC material via the highly conductive rubber. The conductors are spaced sufficiently close to one another to ensure that when energised the PTC material heats substantially uniformly without exhibiting a significant temperature gradient between the conductors and that any abnormal temperature increase increases the temperature of all the PTC material between the conductors in the region of the abnormal temperature increase. The arrangement is such that in use the contact resistance between the conductors and the PTC material is reduced by the amorphous highly conductive rubber interposed therebetween.

Abstract: A self-regulating heating article comprising a layer of material exhibiting a positive temperature coefficient of resistance (PTC) and said PTC layer having at least partially contiguous therewith at least one layer of constant wattage output material. The article operates such that when connected to an electric power source, the current flows through at least a portion of the thickness of the PTC layer and of the constant wattage layer. In a preferred embodiment, upon heating the article, a change in dimensions as well as activation of an adhesive occurs.

Abstract: A resilient snap-on electric heating jacket for heating tubular objects includes a thin sheet of flexible plastic material constituting a radially internal curved surface adapted to engage the surface of the object. A pattern of spaced electrically conductive loops are formed on the radially external surface of the sheet to define an electric heating element. A thick resilient support member of polymeric material coextensive with and overlying the external surface of the plastic sheet and the foil loops is directly secured to the external surface portions of the foil loops and the plastic sheet by an autogenous bond to form a unitary structure generally C-shaped in cross section and capable of being snapped onto a tubular object the outer diameter of which corresponds approximately to the inner diameter of the profile of the unitary structure. The profile of the support member encloses an angle between 180.degree. and 270.degree. and preferably between 200.degree. and 250.degree..

Abstract: Electrical devices which comprise two planar electrodes and a conductive polymer element, at least a part of which is a PTC element. The conductive polymer element has an intermediate portion of increased resistance, resulting from the presence of insulating or high resistance portions within the conductive polymer element, so that when a hot zone is formed in the PTC element, it is located at or near the intermediate portion, away from the electrodes.

Abstract: A method of attaching power leads to a mesh or similar electrode embedded in the surface of a conductive polymer element. A conductor, preferably also mesh, is bonded to the electrode using a conductive adhesive and a polymer layer is applied over the surface of at least the conductor, preferably also over the electrode. The polymer of the coating interpenetrates the openings of the mesh conductor and mesh electrode and bonds to the conductive polymer matrix. This mechanically holds the conductor, electrode, and conductive element in contact with each other.

Abstract: A laminated structure comprises a plurality of double-layer capacitor unit cells, each having a high withstand voltage. A complete capacitor is made by laminating a plurality of unit cells of the double-layer capacitors type and by connecting a plurality of resistors, having substantially equal resistances, in parallel with the respective unit cells. In a preferred embodiment, a high-precision integrated voltage-equalizing resistor is prepared by laying linear resistors on a flexible sheet which is then wrapped around the laminated unit cells.

Abstract: An electrically impedant article comprising an electrode embedded in a polymeric body having dispersed therein electrically conducting carbon black in which the body around the electrode contains a lower percentage of conductive carbon black than do other regions of the body further away from the electrode, the carbon black in said region around the electrode being of higher conductivity than the carbon black in said other regions. The polymeric body preferably comprises a silicone rubber. The article can be a heating tape having a pair of spaced parallel electrodes and may have a positive non-linear temperature co-efficient of impedance.

Abstract: A heating tape comprising a pair of elongate electrodes embedded in a body of electrically conductive material wherein the highest current density in the effective current path between the electrodes as herein defined, is at a location spaced from and intermediate the electrodes.

Abstract: A tubular jacket heater having a C-wise radial cross section with an aperture extending in a parallel direction to the axis is proposed which is used to envelop and preheat a tubular lamp used, for example, in a electrophotographic copying machine. The heater is composed of an inner layer made of an electrically insulating rubbery elastomer, an outer layer also made of an electrically insulating rubbery elastomer and a flexible heater element sandwiched by and entending between the inner and the outer insulating layers. The rubbery elastomer recommended is a silicone rubber with a specified hardness.Different from conventional similar tubular jacket heaters in which the insulating layers are made of a rather rigid plastic resin such as a polycarbonate resin, the inventive heater has an excellent adaptability to the outer surface of the tubular lamp inserted therein so that a greatly improved efficiency of the heater is obtained.

Abstract: The method of manufacturing, composition and product described herein utilize highly electrically resistive carbon black alone or with low resistivity carbon black to form a self-limiting electrically resistive semi-conductor which presents a positive temperature co-efficient of resistance, the methods which are described providing significantly shortened anneal times, manufacturing ease and reliability.

Abstract: A packaging arrangement for an electrical heater unit adapted for adhesive attachment to a surface, for example, to a window of a motor vehicle. The heater unit includes a plurality of heater strips which have an adhesive coating on one face thereof whereby the strips may be secured to the window. The strips are supported in a desired pattern for application to the window by being adhesively mounted on one surface of a backing sheet. The adhesive coated surfaces of the strips are remote from the backing sheet and a removable cover sheet overlies the heater strips. A clearance is provided between the cover sheet and the adhesive coating on the heater strips so that the cover sheet is not contacted by the adhesive coating on the heater strips.

Abstract: A heated rubber mat comprising upper and lower rubber panels and an intervening carbon-loaded electrically resistive rubber heating element. All are vulcanized together to form a unitary mat structure characterized by good flexibility permitting rolling up the mat in any direction and by permanent shape retention, said heating element having spaced, flexible electrodes fully enclosed therein and bonded thereto, along with associated, thermostatically controlled current receiving means, whereby current may be transmitted through the portions of the heating element lying between said electrodes to generate heat and whereby the mat may be maintained at the desired temperature.

Abstract: The invention relates to heating elements comprising conductive polymers which are capable of undergoing a change in dimension. The heating elements comprise a laminar member composed of a conductive polymer and two laminar electrodes connected directly or indirectly to opposite faces of the laminar member, and there are apertures, for example slits, passing through the thickness of the element so that at least one planar dimension of the element can be changed by changing the shape of the apertures. The apertures through the element facilitate its dimensional change. Preferably the laminar member exhibits PTC characteristics. The heating elements are particularly useful in the form of articles in which the element is attached to a heat-responsive sheet, for example a heat-recoverable polymeric film.

Abstract: A self-regulating heating article comprising a layer of material exhibiting a positive temperature coefficient of resistance (PTC) and said PTC layer having at least partially contiguous therewith at least one layer of constant wattage output material. The article operates such that when connected to an electric power source, the current flows through at least a portion of the thickness of the PTC layer and of the constant wattage layer. In a preferred embodiment, upon heating the article, a change in dimensions as well as activation of an adhesive occurs.

Abstract: The invention relates to heating elements comprising conductive polymers which are capable of undergoing a change in dimension. The heating elements comprise a laminar member composed of a conductive polymer and two laminar electrodes connected directly or indirectly to opposite faces of the laminar member, and there are apertures, for example slits, passing through the thickness of the element so that at least one planar dimension of the element can be changed by changing the shape of the apertures. The apertures through the element facilitate its dimensional change. Preferably the laminar member exhibits PTC characteristics. The heating elements are particularly useful in the form of articles in which the element is attached to a heat-responsive sheet, for example a heat-recoverable polymeric film.

Abstract: A method for improving the heat transfer between an elongated electric resistance heating element and a pipe on which the heating element is mounted without use of heat transfer cement comprises utilizing a close fitting elongated rigid channel member to directly cover and press into direct contact with the outer surface of the pipe an elongated electric resistance element arranged lengthwise of the pipe. The heating element has a flat pipe contacting surface and comprises parallel resistance wires encased in a resilient electrically insulating sheath. The channel member is coextensive in length with the heating element and is pressed down against the heating element with substantially uniform pressure and contact to ensure that at least about 25% of the heating element is in continuous contact with the surface of the pipe. The channel member and heating element are entirely devoid of heat transfer cement.

Abstract: A sheet-like thin flexible heat-emitting surface layer and a coextensive thin flexible serpentine heat-sensing layer are overlayed by thin flexible synthetic plastic sheets which are sealed peripherally. Lead wires from an electrical plug to the heat-emitting layer are interrupted by a controller which is operated by current flowing through the heat sensing layer. Increased heat changes conductivity and current in the heat sensing layer, causing the controller to interrupt or reduce power to the heat-emitting layer.

Abstract: A heating tape is described which comprises two longitudinally extending foil conductors and a longitudinally extending tape incorporating heating elements spaced apart along its length. The heating elements are connected electrically in parallel between the heating foils, enabling the heating tape to be powered from one end.

Abstract: An electrically conductive paper comprising glass fibers is made by dispersing electrically conductive materials i.e. electrically conductive fibers or particles, with the glass fibers of a paper-making slurry. Paper having an electrically conductive layer and a nonconducting layer can be made. Heating panels are made by adhering the electrically conductive paper to a wall in much the same manner as is wallpaper. A positive electrical terminal is applied to one end of the paper and a ground terminal is applied to the other end of the paper. A flow of electricity through the paper causes the paper to heat and to in turn supply heat to the room which the wall faces.

Abstract: A continuous composite web from which electrical low temperature heating mats can be produced by transverse cutting at certain positions and possibly by effecting an edge insulation and attaching electrical connections. A method for the production of such webs is also disclosed. The web consists of resistance foil material between two insulating foil layers which are joined in the areas of direct contact to secure the resistance foil. The resistance foil material is in the form of parallel, continuous, longitudinal strips and transverse strips extending transversely to said longitudinal strips at desired intervals and connected thereto to form electrical connections between adjacent foil strips. The transverse strips extend substantially across the total width of the web and can be in the form of an insulation strip having flat foil conductive pieces on the insulation strip.

Abstract: A planar heating element having a thin flat body formed from an insulating thermoplastic resin and electrically conductive powder. The electrically conductive powder is formed in a layer within the thermoplastic resin in the neighborhood of the entire surface of the body. Lead wires within the flat body being positioned near the surface of the body such that the lead wires are electrically connected to said layer of electrically conductive powder. The planar heating element being produced by a method comprising melt-admixing an insulating thermoplastic resin with an electrically conductive powder. The mixture is then extruded, and the extruded body is rapidly cooled.

Abstract: A precision resistor wherein the resistor wire is deposited in a sinuous pattern on the adhesive surface of a thin, flexible tape of electrical insulating material. In winding the tape onto a multibobbin coil form the intermediate flanges of the coil form have a flat portion of reduced radius. A coil of tape is wound on one bobbin with the adhesive side against the bobbin and is passed over the flat portion of an intermediate flange. At the crossover the tape is pressed to conform to the shape of the flange and then passed around the axial body of the adjacent bobbin to commence the winding of the next coil of tape on the adjacent bobbin.

Abstract: A rigid electrical heating element having a thin, rigid, electrically insulating, air-impervious layer and a thick, insulating polyurethane layer formed in situ connected to said rigid layer by a conducting film based upon a synthetic resin, electrically conducting particles and potassium silicate or sodium silicate. Electrodes and corresponding electrical connections are mounted on the film after it has been applied by deposition of an aqueous plastic dispersion of said resin particles and silicate material. The silicates being present in the heating film in sufficient quantity to protect the heating film from attack by the starting reaction components of the polyurethane layer. The rigid layer may be a synthetic resin panel having a decorative heat irradiating surface.

Abstract: The specification discloses a continuous composite web from which electrical low temperature heating mats can be produced by transverse cutting at certain positions and possibly by effecting an edge insulation and attaching electrical connections. A method for the production of such webs is also disclosed. The web consists of resistance foil material between two insulating foil layers which are joined in the areas of direct contact to secure the resistance foil. The resistance foil material is in the form of parallel, continuous, longitudinal strips and transverse strips extending transversely to said longitudinal strips at desired intervals and connected thereto to form electrical connections between two and two adjacent foil strips.

Abstract: An electrically heated laminate including a flexible heater fabric, wherein the heater fabric comprises a woven glass fabric having a layer in contact with electrodes of an electrically conductive mixture comprising a vinylidene chloride polymer and carbon to provide the desired watt density and an outer coating of a vapor barrier of a vinylidene chloride polymer. A fabric softener layer may also be provided between the glass fabric and the conductive coating to impart greater flexibility to the heater fabric.