Abstract: An electrical resistor and method of making the same is disclosed wherein a ceramic substrate is coated with a relatively rough dielectric film which is subsequently coated with a thin metal film such as nichrome.

Abstract: Circuit protection devices comprise a PTC conductive polymer element and means for minimizing the adverse effects of carbonaceous dust evolved by the PTC element when it is tripped. An enclosure encloses, but is spaced apart from, the PTC element. In one embodiment at least part of the interior surface of the enclosure is composed of polytetrafluoroethylene, a ceramic or another material which discourages the formation of permanent low resistance paths through carbonaceous material lying on its surface. In another embodiment the enclosure has a large internal surface area compared to the volume of the PTC element. In further embodiments, electrical leads are connected to and pass through the enclosure, and at least one of the leads is insulated along its length and/or the leads pass through opposite ends of the enclosure.

Abstract: An electric heater incorporating simple support structure therefor. A frame is insulated from an electric resistance heater coil by insulated supports mounted within beam members of the frame. The supports incorporate structural features enabling the use of simplified supporting beams. The support insulators include additional structural features for retaining the resistance wire in place and for simplified engagement therewith. The insulators may project on both sides of the support beams and retain heater wires in two planes. The support insulators further provide an integrated structure easily fabricated and simply assembled to the frame.

Abstract: An electrically heated glass pane includes a plurality of heating conductors (2) comprising a family of parallel conductors extending between a pair of power supply conductors (3) both disposed on and burnt-in a surface of a glass pane (1). A strip (4), of non-conductive material, covers conductors (3) and extends laterally from the edges of the conductors. The conductors (2) merge into the conductors (3) at a transitional region (7) broadened by an increasing flare so that the cross section of the region, determining the electrical resistance, is greater than the cross section of the conductors (2) providing resistive heating. A layer (12) which covers the same area as the strip (4) may be disposed below each conductor (3), directly on the surface of the glass pane (1). An opening (16) is recessed in layer (12), so that the conductors (3) are connected directly with the surface of glass pane (1).

Abstract: A sealing device for forming seams in heat-sealable packaging materials is disclosed having an electrical resistor heating element for generating heat. In order to transmit heat to a sealing surface of the sealing device in such a way that uniform temperature distribution is attained on this surface, a sheath of a highly heat-conductive metal, such as aluminum, is provided between the heating element and the sealing device. The sheath is fitted tightly into the sealing device.

Abstract: Electrical devices comprising a layer of a PTC conductive polymer and a sheet electrode in contact with each face of the PTC layer. The electrodes extend to the sides of the layer and the sides of the layer are concave, and this results in improved performance. Preferred devices are circuit control devices which protect a circuit from increases in current resulting from a fault.

Abstract: This invention relates to a spacer clip for an injection molding electric heating element. A number of clips, each formed of a continuous band, are slipped over one end of the heating element and slid along to predetermined positions. Each clip is then crimped to the heating element in that position which forms a finger which extends radially from the heating element in a predetermined orientation. The heating element with the spacer clips attached is located in a suitable mold for casting and the fingers of the clips locate each coil of the element with sufficient clearance from the mold and the other coils. The thickness of the conductive heater cast around the heating element is important to provide uniform heat transfer. The spacer clips are formed of a material such as stainless steel which has sufficient pliability to be securely crimped to the heating element, but sufficient strength to reliably retain the heating element in position.

Abstract: An electrically conductive element comprises a support (perferably a flexible continous polymeric film) and fibrous material (preferably a spun glass fiber web) which is partially embedded in the support and partially protruding therefrom, the protruding fibrous material being part of a conductive layer comprising randomly distributed fibers having conductive material adhered thereto. The element can be prepared from a conductive composition containing conductive particles dispersed in a liquid medium (preferably an aqueous dispersion of carbon particles) by applying said composition to a substrate comprising a support and fibrous material which is partially embedded in one surface of the support and partially protruding therefrom, and then drying to evaporate the liquid medium. The elements are particularly useful as heating elements which comprise electrodes so that current can be passed through the conductive layer.

Abstract: Polymers having low surface energy, e.g. fluorocarbon polymers, are rendered printable by conventional methods, e.g. offset printing, by incorporating a suitable particulate filler in the polymer, and shaping the filled polymer under conditions which result in the surface of the shaped polymer having irregularities which correspond to the particles of the filler. Suitable fillers comprise particles having at least two dimensions in the range of 1 to 40 microns; glass fibers are particularly satisfactory. Extruded insulating polymeric jackets for electrical components, e.g. strip heaters and wire and cable, can readily be marked by use of the invention.

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: A flexible device which can be detachably mounted on a window, such as a vehicle window, in order to prevent icing or fogging. The device is a semi-flexible sheet of layered materials having a length and width substantially coterminus with the window and having arranged at intervals along its two dimensions, holders which are used to detachably mount the device on the window. The sheet materials include a rather stiff supporting layer which acts as a backing surface of the sheet and a heat reflecting layer on the sheet side which faces the window when mounted. Optional layers include an insulating layer, a decorative layer, a silicone rubber electrically conductive layer and braided copper electrode strips for connecting the conductive layer to an electric source and causing the generation of heat from the conductive layer. The holders are of a length which will position the sheet a distance of about 5 to 15 mm away from the window.

Abstract: A method and apparatus for parallel-type heating cables. In accordance with the present invention a heating core element is formed by connecting two essentially parallel bus wires with a plurality of electrically conductive splices to a centrally disposed resistive element and around which heating core element a protective sheath is formed. The present invention permits this heating core element to be formed by splicing the spaced apart, essentially parallel wire elements followed by a single extrusion application of a protective sheath.

Abstract: A continuous flexible cable heater having a coil continuous conductor in a plastic casing. The conductor has uncoiled regions spaced therealong between coiled regions to permit bending at a radius less than twice the jacket outside diameter. A heater assembly has the cable disposed on a support in closely folded serpentine planar array. A sensor portion of the continuous cable is folded over and adjacent the upper surface of the planar array and includes fusible protective means to cut off the heater in the event of overheating of the liquid or excess current draw.

Abstract: A radiant panel type heating apparatus includes a heating element comprising a sheet of electrically conductive paper which generates heat as a result of resistance to current flow therethrough. The heating element includes spaced apart primary conductor elements comprising thin copper strips which are sewn to the conductive paper to provide uniform distribution of current flow through the paper from one conductor element to the other. The heating element is sandwiched between a main insulative panel member on one side and a heat conductive panel member one the other side to form a heat radiating surface. The heating element is secured in assembly with the panel members by strips of non-conductive and heat resistant double sided adhesive tape. The panel type heating apparatus may be provided in various geometric shapes and includes a thermal switch and fuse assembly to limit the maximum surface temperature of the heating element.

Abstract: Circuit protection devices which comprise two columnar electrodes and a conductive polymer element, at least a part of which is a PTC element. The device is so constructed that if a hot zone forms in the PTC element when current is passed through the device, it forms at a location away from the electrodes, thus increasing the useful life of the device. In one preferred embodiment, the conductive polymer element has an intermediate portion of increased resistance, thus causing the hot zone to be located at or near the intermediate portion. The intermediate portion may be of reduced size and/or be composed of conductive polymer of relatively high resistivity.

Abstract: In a thermal target suitable for live weapons fire, a resistive material is disposed between layers of insulation and screen like continuous electrodes. Portions of insulation are removed at predetermined locations to expose the resistive material and the continuous electrodes are fastened to the exposed resistive material. When an electrical potential is applied to the continuous electrodes the target emits thermal radiation in order to simulate a known thermal image for an infrared sighting device.

Abstract: Electrical heating apparatus, including a frame formed of insulating material having an opening formed therethrough, a heating element formed of positive temperature coefficient material having two opposing outer surfaces and being disposed in the opening formed in the frame, an electrically-conducting current supply contact layer disposed on each of the two opposing outer surfaces of the heating element, an electrically conducting current input electrode plate formed of yieldable material being anchored in the frame and being disposed on each of the contact layers forming an integral structural unit enclosing the heating element, and a heat conducting plate formed of insulating material disposed on each of the electrode plates receiving heat transfered through the contact layers and clamping the heating element under pressure.

Abstract: An improved electrical heating element is constructed to increase the amount of electrical wire per unit space available for plug-type convection heating units. The heating element includes a metal frame structure with a plurality of spaced support elements and a plurality of spaced removable cross bars connected thereto. A plurality of ceramic heater support blocks, each of T-shape in plan, with spaced end faces are arranged end to end and have undercut grooves which receive a cross bar and are interposed between the support elements. A continuous electric resistance heating wire has a series of parallel spaced inverted U-shaped wire sections. The wire sections are arranged in groups. Each block has a support boss of reduced width adjacent one end face adapted to extend between the strands of a section of the heating wire. Each block has a pair of spaced bosses adjacent to its other end face which extend laterally outward of the support boss.

Abstract: A self-regulating electrical heater comprised of a material which exhibits a positive temperature coefficient of resistance. The heater has a generally rectangular cross-section which provides greater thermal stability and reduces the number of hotline failures.

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 heating device (20) is provided that may be utilized in either a film packaging machine or a thermoforming machine. Heating device (20) includes a frame (32) that carries a plurality of eyelets (36) that are utilized to suspend an elongated ribbon heating element (34) so that apart from contact with the eyelets (36), the elongated ribbon heating element (34) does not contact any other portions of the heating device (20). This construction provides for very rapid heating and cooling response times resulting in an energy savings and a simplified packaging or thermoforming device, while providing accurate heat control.

Abstract: An improved electrical heating molded-element or unit in which a heating wire is embedded or confined in one side of a fibrous layer formed by molding inorganic fibers into a given thickness, characterized in that a portion of said element or unit in the vicinity of the embedded heating wire is treated to provide a zone in which the density, heat conductivity and fire resistance are greater than those of the remainder. With this electrical heating molded-element or unit, it is possible to extract effectively the amount of heat generated by heating wire. This element or unit can be used over an extended period of time with safety but without causing local disintegration thereof owing to the expansion or contraction of the heating wire.

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: The invention relates to novel electrical devices which are useful for example as heaters and temperature sensors, and which comprise at least two electrodes, at least one PTC element, at least one relatively constant wattage element, and at least one current-directing element which directs the current, when the device is first connected to a source of electrical power, so that the effective initial resistance of the device is greater than it would be in the absence of said element. Thus the invention provides a solution to the problem of current inrush in application of PTC devices in which substantial current passes through the device at operating temperatures. The invention also includes the use of the novel devices in applications in which current inrush is not a problem.

Abstract: An aquarium heater that is disposed on an outside surface of the aquarium tank for maintaining the water in the tank at a selectable temperature. The heater is preferably supported by a hanger or holder from a top edge of the tank and has a heat transfer plate disposed in intimate contact with a side or back wall of the tank. The heater includes, in addition to the heat transfer plate, a plastic or phenolic housing, a heating element, insulation and a settable thermostat contained in a temperature-sensing section of the housing. When the tank water is below a threshold temperature the thermostat closes coupling power to the heating element, which is preferably a rope-type resistance heater covered by a metal foil blanket, and when the temperature of the water reaches the threshold the thermostat temporarily opens to uncouple power to the heating element.

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 strip or film panel is connectable to a source of electrical power and is sandwiched between one or more facing panels of flexible or rigid material, and when connected to a source of electrical power, radiate heat from one or both sides. In one embodiment, insulation and a reflective sheet may be incorporated so that one side of the assembly remains cool and the other radiates heat. If required, the assembly may be used in any location requiring heat and in which the panels can be mounted such as in walls, ceilings, floors and the like. In another embodiment, the panels are flexible and can be wrapped around the object to be heated. If desired, the panel can be molded into a helment shaped configuration and can be used, for example, as a hair dryer and another embodiment, a flexible panel can be routed around dowels to give an increased cross sectional heat source area as compared with a planar sheet.

Abstract: A heating element for use in an electric blanket or the like including conductors spaced apart in a positive temperature coefficient (PTC) material which serves as a self-limiting heater. The conductors are separated by a spacer which prevents the conductors from engaging each other when the PTC material softens or melts during annealing thereof. A coating of material having a higher melting point than the PTC material is placed over the PTC material to maintain its shape during the annealing process.

Abstract: A heating cable having spaced helically wound conductor wires separated by a layer of positive temperature coefficient material which functions as a self-limiting heating element. At least one of the conductor wires is helically disposed on a stranded core of insulating fibers which have been coated and impregnated with conductive carbon.

Abstract: A heater cable with coaxial inner and outer conductors and an intermediately disposed resistance heater. The heater is spaced from the inner conductor by radially extending alternating conductive and non-conductive separators with current being delivered to the heater by the conductive separators. The heater is deformed so as to contact the outer conductor at spaced locations to thereby define plural parallel heating circuits.

Abstract: A modular, constructional heating unit, useful, e.g., for the fabrication of interior partitions, is comprised of a panel member provided with at least one elongate rectilinear cavity, the longitudinal axis of such cavity being parallel to a face surface of the panel, said cavity being exteriorly communicating at one or both of its ends, and said cavity containing an electrical heating element.

Abstract: An electric resistance heating unit in which the heating element is a thin, foil-like strip of expanded metal supported on edge substantially along its entire length on a board of insulating material. The heating element is formed in a serpentine pattern, and its bottom edge is embedded in a similar serpentine groove in the upper surface of a ceramic fiberboard and cemented therein.

Abstract: Laminated heater plate assembly is formed from a plurality of layers of glass cloth and/or glass mat and epoxy resin which are laminated together under heat and pressure. One or more thermally conductive heater members are mounted in a cut-out region(s) in a pre-cured or "C" stage laminate top portion of the assembly while a plurality of uncured or "B" stage glass mat and epoxy resin laminations are stacked, assembled under the "C" stage portion and heater portion(s), and bonded to each other into a rigid, warp-free heater plate assembly which can be repeatedly subjected to steam or hot water without damage. Preferably, the resin density after bonding in the region of the edges of the heater portion(s) and the adjacent surrounding edges of the cut-out region(s) is greater than in locations spaced further from the heater portion(s) in order to enhance the sealing of the assembly in the most critical areas thereof.

Abstract: A heat absorbing and reflecting disc-shaped device having a flat top and a convex bottom and an irregular radially inward-extending cut-out and a plurality of randomly spaced throughbores, said disc being removably mounted on an electric range between the electric coil and reflector pan and resting on the latter. The device is preferably formed from a predetermined mixture of sand clay, water and sodium silicate and may be glazed, if desired. An irregular generally diamond-shaped central opening, preferably, is provided.

Abstract: A sheath heater having a heating wire embedded in a ceramic insulator such that the thermal deformation of the heating wire is substantially prevented, wherein the heating wire is formed of a nichrome-based wire having an Al-rich surface layer so as to permit forming an oxidation-protective alumina layer on the surface of the nichrome-based wire.

Abstract: A heating element for use in an electric blanket or the like including conductors spaced apart in a positive temperature coefficient (PTC) material which serves as a self-limiting heater. The conductors are separated by a spacer which prevents the conductors from engaging each other when the PTC material softens or melts during annealing thereof. A coating of material having a higher melting point than the PTC material is placed over the PTC material to maintain its shape during the annealing process.

Abstract: Electrically parallel but positionally serial, helically wound segments of heating wire in a cable are each controlled by a chip (thermistor) and are connected to the cable proper by wrapping around notches formed in the insulation of the cable proper at first one side and then the other of the cable. The inner and outer-faces of each chip are connected into each segment by direct contact or by leads at spaced points between which the heating wire is severed. An extruded casing is shrunk-fit over the other parts.

Abstract: The invention relates to novel electrical devices which are useful for example as heaters and temperature sensors, and which comprise at least two electrodes, at least one PTC element, at least one relatively constant wattage element, and at least one current-directing element which directs the current, when the device is first connected to a source of electrical power, so that the effective initial resistance of the device is greater than it would be in the absence of said element. Thus the invention provides a solution to the problem of current inrush in applications of PTC devices in which substantial current passes through the device at operating temperatures. The invention also includes the use of the novel devices in applications in which current inrush is not a problem.

Abstract: Compacted, granular, fused magnesia used as thermally-conducting electrical insulation in tubular, electrical resistance elements is substantially improved in thermal conductivity through the addition of 0.1 to 10.0 percent of a glass comprising CaO, B.sub.2 O.sub.3 and optionally Al.sub.2 O.sub.3 and method of making said tubular, electrical resistance elements.

Abstract: A cast body of concrete material having abrasive surface portions contains an electrical heating element to provide a warmed resting place for attracting and warming animals thereon, such as reptiles while providing an abrasive, sandy exterior to aid reptiles when shedding their skin.

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: An electric heating element for igniting gas fuel comprises a hermetically sealed envelope made of at least 99% pure alumina and filled with a non-oxidizing gas such as hydrogen or one of the inert gases. A self-supporting coiled coil of tungsten or other refractory metal conductor dimensioned to carry a linear power loading of at least one hundred watts per inch is disposed in the envelope with coiling of the coiled coil pressing the peripheral surfaces of the coiled conductor into thermal and mechanical contact with the interior wall of the envelope. Terminals are provided for supplying current to the conductor at said power loading to heat the exterior of the envelope wall to a temperature above 900.degree. centigrade.

Abstract: An electrical heating cable which limits power output once an established temperature limit is reached. The cable includes a high-resistance element and a temperature-sensitive variable resistance element electrically connected in series between two electrical conductors otherwise insulated from each other by insulating material. The temperature-sensitive resistance undergoes a substantial positive increase in resistivity when the temperature of the cable nears the established temperature limit. The increase in resistivity substantially reduces the heat-generating current flowing in the cable to limit the power output.

Abstract: A refractory, granular electrically insulative composition useful as an embedding composition for electric heating coils comprises fused and granulated, possibly ground, difficultly fusible, ceramic and possibly oxide-ceramic material having polyalkylsiloxane, e.g. polymethylsiloxane, or polyarylsiloxane admixed in a proportion of from 0.5 to 5.0% added weight. Use of the composition is suitable with tubular heaters which have been produced with it and which, after manufacture and before being brought into use, have been subjected to a heat treatment at a temperature of at least 65.degree. C, for a period of at least 10 minutes. An electrical heating element comprises a housing which is embedded in the composition wherein the ceramic and possibly oxide-ceramic material has been ground.

Abstract: A thermally conductive refractory electrical insulating embedding composition comprising granular magnesium oxide and granular fused magnesium iron alumino silicate; and electrical heating assembly having an electrically conductive heating member and a jacket and disposed between said member and said jacket a thermally conductive refractory electrically insulating embedding composition comprising granular magnesium oxide and granular fused magnesium iron alumino silicate.

Abstract: A heat recoverable article is so configured that it can be positioned around a pipe or cable joint or splice which it is desired to encapsulate or seal. Means for sealing a splice involving a plurality of cables of the same or varying sizes are provided. The article includes a closure means for holding the article together after it has been positioned around the splice to be sealed. In a preferred embodiment, the inner surface of the article contains a heat activated adhesive or sealant to environmentally encapsulate the splice and the outer layer of the article is a heat recoverable insulating material. In a particularly preferred embodiment, the article has self-contained heating means, which heating means comprises a polymeric material having dispersed therein a conductive filler, said heating means exhibiting a positive temperature coefficient of resistance so as to render it self-regulating.

Abstract: An improved method for manufacturing an electrical heating device including the steps of placing an electric heating element comprising an electrical resistor, electrical insulation material, and a metallic jacket within a cladding tube, filling the remaining space in the cladding tube with a metal powder having a high thermal conductivity, densifying the powder after the powder is placed in the cladding tube, and subsequently sintering the powder. The improvement of the invention comprises the steps of mixing the metal powder, prior to the step of filling, from grain sizes which produce a high filling density in the cladding tube. The metal powder is then additionally densified, subsequent to the step of densifying previously carried out but prior to the step of sintering, by reducing the diameter of the cladding tube. The diameter of the cladding tube is then further reduced to compensate for shrinkage of the metal powder during the step of sintering.

Abstract: An electrically conductive resinous composition of a copper flake, the surface of which has been cleaned by removing therefrom impurities and/or oxides, a resinous binder, an amount of copper flake in said resinous composition being from 25 to 70 percent, the impurities in said copper flake being less than 7000 ppm, said resinous composition being cured with a curative comprising a polyamide or an anhydride, or mixtures thereof; these compositions are suitable for uses such as heating panels or conformable heating shapes.

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: A modular heating section for removing or preventing the formation of ice on the walls of navigation locks, loading docks, ferry slips, or the like. Ice formation on the walls of navigation locks is compressed by successive vessels to the extent that larger vessels are unable to enter the locks. To avoid this happening, ice is chipped from the walls of the locks, which is time-consuming. As well, chipping of the ice results in damage to the concrete walls which must then be repaired. To overcome this problem, the present invention proposes the use of a modular heating section comprising a rigid panel having means for securing the section to a navigation lock wall, loading dock, or the like at a location where ice formation occurs, the panel being made from a heat conducting material. The panel includes heater means situated therein, the heater means adapted to distribute heat throughout the modular heating sections.