Abstract: The present invention provides a probe for measuring the level of a liquid, including a conductor partially immersed in said liquid and whose degree of immersion depends on said variable level to be measured, the resistivity of which conductor depends on the temperature. The conductor is for example etched on an insulating support which is a better conductor of heat than air. The result is a very good linearity for rapid measurements, higher accuracy and a great mounting simplicity.

Abstract: A thermal head comprising heating resistors with their temperature coefficient of resistance being negative at normal temperature and invertible to be positive as the temperature rises.

Abstract: A contact lens sterilization device has a case which is generally made of synthetic resin having defined therein: a bottom chamber for receiving the heating element; a middle chamber for receiving a contact lens; a top chamber for receiving an electronic circuit for controlling the heating element therein so as to achieve a better thermal separation between the top chamber and the bottom chamber. A heating element which may be a PTC semiconductor device is secured to the lower surface of the wall separating the middle chamber and the bottom chamber by way of a heat transmission plate and secured by a holding plate and columns appending from the separation wall. The two electrodes of the heating element may be electrically in contact with the heat transmission plate and the holding plate, respectively.

Abstract: A travel iron with a plastic housing defining a hot water reservoir, with a plastic sole plate as its lower surface. An immersible PTC resistor is used to heat the water and to protect the iron from overheating. The heated water heats the sole plate and serves to control the temperature of the sole plate. The handle is reversible and is secured to the forward end of the housing. When reversed the handle provides a winding area about which the electrical cord may be wound for storage.

Abstract: The disclosure is directed to an improved trouble detecting method of a temperature control device including a thermo-sensitive element such as a thermistor or the like for application to a heating apparatus, for example, a cooking apparatus or the like. The detecting method includes the steps of energizing the temperature control device for a predetermined period of time, and comparing an output of the temperature control device and a reference output for judgement.

Abstract: Novel acrylonitrile butadiene and carboxylated acrylonitrile butadiene elastomeric admixtures compounded with various amounts of mineral fillers such as silicates, silicas, etc., carbon blacks, and plasticizers such as esters, epoxidized polyesters, etc., are useful as continuous temperature-sensitive solids when applied to metallic conductors as coatings whereby one leg acts as a conductor and the other is used as the sensing leg. These electrical properties of these admixtures such as volume resistivity, impedance, and reactance are uniquely sensitive to temperature changes from room temperature to at least 90.degree. C. and thus offer new and important circuit design opportunities for monitoring and detecting temperature changes. These admixtures which are essentially thermosetting may be combined with other resins such as polyvinyl chloride and used thermoplastically. In these cases, the elastomer becomes the plasticizer.

Abstract: A cascaded fluid heating for electrically heating to fluid, such as a gaseous fluid in a flameless torch, to a high temperature includes a pump to pump a relative constant stream of fluid through a pair of heating chambers arranged in series. A first electric heating element formed of a nickel-iron alloy having a substantially linear positive temperature coefficient of resistance up to 1100.degree. F. is disposed in the first chamber and heats the fluid stream to a first temperature. A second heating chamber receives the heated fluid from the first chamber and contains a second electric heating element of a material, such as Kanthal A, which does not oxide at temperature up to 2000.degree. F. for heating the fluid to a higher temperature. The first electric heating element acts as a sensor for a temperature controller for the first heating element whereby the current supplied by the controller to the first heating element responsive to the changes in resistance of thereof.

Abstract: A bushing controller circuit for regulating the current flow through a fiber glass bushing to thereby control the temperature of the molten glass being drawn into fibers is disclosed. The bushing temperature is measured by a plurality of thermocouples which produce an average temperature reading that is used to control the power fed to the bushing. The bushing controller circuit is a three-terminal device connected across two sections of the bushing to regulate relative current flow in the two sections, in order to control the amount of fiber produced by each section. The bushing controller circuit includes a pair of timing circuits which operate in response to the polarity and magnitude of a control signal, produced at a remote control panel, to control the conductivity of a corresponding pair of current control devices connected across respective sections of the bushing. A reset circuit produces a signal corresponding to the zero crossing of the input AC power to synchronize the timing circuits.

Abstract: A battery warmer includes a positive temperature coefficient (PTC) element of a size to maintain the contents of a battery to which it is attached in the range of 45.degree. to .phi..degree. F. in ambient temperatures of -30.degree. to 75.degree. F., and a housing for the PTC element, preferably of foamed plastic. The housing is mounted to a flat side of the battery, either adhesively or mechanically. A method of making the warmer includes securing paper to two broad, parallel surfaces of the housing to provide one surface that will take adhesive and another to bear printed instructions, and which together inhibit warping of the housing during its manufacture.

Abstract: A temperature sensor in a heating tape includes first and second electrical conductors, a substance such as salt in electrical contact with each of the conductors, said substance having a significantly different electrical resistivity when the substance is at a temperature below a transition temperature range than when the substance is at a temperature above said transition temperature range.

Abstract: A method of equalizing production on a split fiber glass forming bushing is described involving averaging the temperature measured across a bushing face plate, and controlling the power input to the bushing in response to that measured average. The two halves of the bushing are controlled by placing a variable resistor in the power supply lines to the bushing and adjusting current input to the sides in response to variations in weight or yardage measured for the two strands produced by the split bushing.

Abstract: A current controller interface accepts a variable voltage at its input and develops a current at its output which corresponds directly with the input variable voltage. Its apparatus is usually associated with a program controller as an input and a microscope which has a heated element as the output. The apparatus uses a control circuit which is coupled to a controllable resistance semiconductor device, which device has an output which varies in resistance in accordance with variation in input current. The output of the variable resistance device is coupled in series with the heating coil of the microscope, the power supply and current sensing resistor. The resistor develops a feedback voltage which is applied to the control circuit so that when a change in voltage is applied to the input the output from the current sensing element will change until it balances the current being applied at the input. When the balance occurs, no further change in output current will occur.

Abstract: An indicating lamp and a PTC thermistor are connected in series across an electric power source by an ignition switch which simultaneously actuates apparatus to intermittently energize a diesel engine glow plug. Further apparatus is effective to make and break a low resistance shunt path around the indicating lamp in response to deenergization and energization of the glow plug. The indicating lamp and PTC thermistor both are electrically energized to self heat and both have electrical resistances increasing sufficiently with temperature to drop substantially most of the supply voltage when hot and prevent energization of the cold other. The indicating lamp heats much faster than the PTC thermistor and so energizes during the initial energization of the glow plug to signal the vehicle operator to not attempt starting of the engine.

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: Disclosed herein is an apparatus for closely covering with a plastic film at least one surface of a base sheet such as identification card to improve the durability of the base sheet and to prevent any unauthorized alteration of information described thereon. The above apparatus includes a pair of conveying and pressing rollers and a heat radiation lamp incorporated therein to heat the circumference of at least one of the rollers. The base sheet and the plastic film overlaid are preheated by direct heat from the heat radiation lamp while being conveyed toward the pair of rollers, thereby achieving a high-speed processing and prevention of base sheet deformation. Also disclosed is an apparatus equipped with a heat transmission member along the base sheet feed path of a base sheet travelling path. The heat transmission member is adapted to present the base sheet and the plastic film, and may be formed by a part of a reflector plate.

Abstract: A control for modulating the duty cycle of diesel engine glow plugs has two heat sensitive, normally closed switches each thermally coupled to a respective positive temperature coefficient (PTC) of resistivity heater in turn thermally coupled to and mounted on a common heat sink. The heat sensitive switches are serially connected to each other, to an ignition switch and to a glow plug relay. The PTC heaters are connected to a point between the heat sensitive switches and the relay and to ground. A third PTC heater is mounted on the heat sink intermediate the first and second heaters and thermally coupled to the heat sink. The third heater is connected to an alternator and serves to cut off power to the glow plugs after a selected after glow stage. The two heat sensitive switches can be selected to open at approximately the same temperature for a random operating mode or at slightly different temperatures for a sequential operating mode.

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 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 temperature-controlling circuit including a heating element, a portion of which is shunted by a proportional PTC thermistor having a low rate of charge of resistance with increasing temperature that controls current to the shunted and unshunted portion of the heating element to provide a proportional control of temperature. Additional embodiments are disclosed in which additional circuit elements are employed to further control current through the heating element, and in which a second thermistor connected in series with the shunted portion of the heating element accommodates wide voltage swings.

Abstract: An electrical heating apparatus, and particularly a bedcover preferably in the form of a blanket, protected against an overheating condition and in which electrical current flow through a heating element is controlled by a pair of gate controlled bidirectional semiconductor switches electrically connected to one another in series and in front-to-front orientation. The gates of the semiconductor switches are connected through a temperature sensitive capacitor which triggers the semiconductor switches from a conductive to a nonconductive state in response to the sensing of an overheating condition.

Abstract: A temperature regulating device for electric heating apparatus has a thermostat for controlling the operation of the apparatus, the thermostat being thermally coupled to a regulation resistor connected in series with a resistor, the resistance of which varies as a function of temperature.The latter resistance is thermally coupled to a differential correction first heating resistance and to a shift correction second heating resistance, these two resistors having different time constants and being energized, respectively, when the heating apparatus is turned on by the thermostat and when it is turned off.

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 contact lens disinfector has a molded plastic casing with wells at opposite ends for receiving the respective lenses and the disinfecting solution. Caps are removably threaded onto the casing over the wells. A thermistor heater is embedded in the casing between the wells to provide a low temperature (60.degree. C. -80.degree. C.) heater for the solution for an extended heating cycle, thereby to inhibit deterioration of the lenses due to loss of transparency.

Abstract: A heating circuit for an electric blanket or the like comprises a cable (1) formed from a heater conductor (2) separated from a sensor conductor (3) by temperature sensitive material (4) and two series resistor-diode pairs (R1-D1 and R2-D2) each connected between ends of the conductors (2, 3) so that each pair conducts in series with the impedance (Z) of the material (4) during respective half-cycles of an AC mains supply, the arrangement being such that general overheating of the cable (1) or localized overheating anywhere along its length reduces the impedance (Z), (possibly to zero if the material (4) melts), such that the current through one or both of the resistors (R1, R2) heats the resistor(s) and blows a thermal fuse (F) to terminate heating. The thermal fuse (F) may be replaced by a resettable interruption element, namely a self-regulating PTC resistive element.

Abstract: A temperature control system for electric surface heater of piled layers of a heating element across which a commercial AC source current is fed and a thermosensitive electrode opposing the element through thermosensitive element showing negative impedance characteristics with temperature rise. In the system, an AC signal voltage different from the source current is applied between the heating element and the thermosensitive electrode, and excessive variations in the signal voltage responsive to the negative impedance of the thermosensitive element is detected to disconnect or connect the heating element and the source.

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 heater immersible in liquids such as water suitable for water beds and a method for producing the heater are disclosed. The heater includes two-spaced apart metallic electrodes interconnected by a conductive polymeric matrix. A water-impermable barrier completely surrounds the polymeric matrix. A jacket of plasticized polyvinyl chloride can be placed around the barrier. The barrier also prevents plasticizer from the polyvinyl chloride from penetrating and damaging the conductive polymeric matrix.

Abstract: A glass-ceramic cooktop surface is provided with a temperature sensor integral with the glass ceramic plate of the cooktop. The temperature sensor utilizes the temperature resistance characteristic of the glass ceramic plate as a means of monitoring the temperature of the plate and is formed in the heated areas of the glass-ceramic plate. The sensor comprises pairs of metallized conductive strips fired to the underside of the plate and terminated in a cool region of the plate. A continuity resistor is provided at the termination point of each pair of strips to distinguish between cold glass conditions and a defective sensor. One strip of each pair is connected to a further metallized strip which surrounds the periphery of the glass and forms a common ground for a heating unit control circuit and is also used as a broken glass detector. Each sensor forms one leg of an AC voltage divider and is connected to an associated control circuit.

Abstract: An immersion heater is disclosed having a heating member with a small thickness and comprised of PTC thermistor material. The heating member has the same heat contact between each of its two major surfaces and the medium to be heated. A Curie temperature T.sub.C and a specific resistance .rho..sub.T.sbsb.C of the material are dimensioned such that with a given operating voltage U a temperature regulation for the range with the positive temperature coefficient of the material results. By use of the upper limit of the Curie temperature T.sub.C, extensive protection against fire can be obtained in the case of inappropriate handling of the immersion heater.

Abstract: A proctologic device is described for therapeutically treating hemorrhoids extending from the anal canal wall of a patient. The device includes an anal canal appliance for intimately contacting the anal canal wall and hemorrhoids. The appliance has sufficient length to extend from the anus to the rectum and sufficient diameter to intimately contact the wall tissues without overly stretching the sphincter muscles. The appliance contains an internal electrical resistor for generating heat in response to the application of electrical energy and a temperature transducer for sensing the temperature of the appliance in the anal canal. The device has a portable case containing an electrical energy storage battery and a control circuit for controlling the application of the electrical energy to the resistor to maintain the temperature of the appliance above body temperature.

Abstract: A heater is disclosed having a PTC thermistor heating element rigidly wedged in an intermediate space of the member to be heated by use of at least one wedge-shaped member. The wedge-shaped member has a surface which is at least the size of the heating elment so an optimum heat transmission is guaranteed.

Abstract: A heating device is disclosed having a disc-shaped heating element consisting of PTC thermistor material typically operated by a network voltage of 220 volts. The PTC thermistor material has a cut-off control property at a desired cut-off temperature so as to minimize further heat rises of the heating element above the cut-off temperature. In this fashion, the possibility of fire damage is reduced. The heating element has a specific heat output of greater than 50 watts per cm.sup.2 and the PTC thermistor material is selected to have a Curie temperature which is at least 50.degree. K. higher than the cut-off temperature. A heating body is provided to affect a substantially even dissipation of heat from two sides of the heating element.

Abstract: A heating device having a thermal store provided with an electrical heater has said heater controlled by a charge control circuit which includes a programme generator delivering an output signal in the form of a programme corresponding to a load balancing condition and includes a state of charge sensor which delivers a state of charge signal compared with the programme in a comparator. The heater for the store comprises a plurality of heating elements, the number of which brought into operation to charge the store is controlled by a weather signal provided by an outside temperature sensor. Preferably the comparator provides a delay from the beginning of the off-peak period before energization of the heater starts.

Abstract: The present disclosure relates to a heating unit for heating fluid such as air, in which a plurality of positive temperature coefficient (PTC) semiconductors are aligned in parallel to define clearances between each PTC semiconductor for the passage of the fluid. Each PTC semiconductor is provided with two electrodes disposed on the surface thereof for rapidly generating heat therefrom.

Abstract: Power is applied to an electrical element in maintaining a thermal system at stabilized conditions and a feedback signal is derived to control the electrical input to the heating element by linearly combining functions of the current through the heating element and the voltage drop thereacross respectively. In one embodiment, each of the linearly combined functions in the feedback signal can be varied independently to change the stabilized conditions of the thermal system, while in another embodiment a microprocessor is incorporated to provide such variation for a sequential range of stabilized conditions.

Abstract: An apparatus for regulating the temperature of a model engine glow plug filament. Between pulses from a power circuit, an amplifier applies its output voltage to a filament current path comprising the filament and a resistive circuit. By means of feedback to the amplifier, the filament voltage is kept at a predetermined reference, and the output voltage is thereby an indication of the filament resistance, which is related to its temperature. The output voltage charges a capacitor whose discharge time determines the "on" time of the power pulses. By this method, temperature is regulated, and power is totally cut off when the filament temperature gets sufficiently high.

Abstract: Flexible polyvinyl chloride insulation for wire is made conductive at elevated temperatures activating a sensing conductor and eliminating thermostatic controls. Conduction through the insulation is imparted by adding compounds such as nonylphenoxy poly (ethyleneoxy) ethanol, certain metallic salts of alcohol sulfates, mixed ortho, parasulfonamides, and liquid crystal compounds.

Abstract: A clothes drier, in which a drum having an opening for charging clothes therethrough, an air intake port and an air exhaust port is rotatably supported in a cabinet. The air heated by a thermistor having a positive temperature coefficient is fed into the drum. This heat generating body tends to lower the heating value as the temperature rises, thus dispensing with a protective or safety means such as a thermostat.

Abstract: Flexible polyvinyl chloride insulation for wire is made conductive at elevated temperatures activating a sensing conductor and eliminating thermostatic controls. Conduction through the insulation is imparted by adding compounds such as nonylphenoxy (ethyleneoxy) ethanol, certain metallic salts of alcohol sulfates, mixed ortho, parasulfonamides, and liquid crystal compounds.

Abstract: The leakage current thermostat is utilized in an electric heater assembly including a housing, a heating element mounted in the housing, electrical supply lines to the heating element and an electrically insulating material in contact with at least a portion of the heating element. The material has a temperature-resistance relationship such that the leakage current therethrough is a steep function of temperature. A leakage current thermostat includes a thermostat control circuit which is coupled to the supply lines and which is operative to control the current to the heating element in response to changes in the leakage current. The heating element is preferably formed by printed circuit techniques on a ceramic material which is affixed in a layer to a metal (conductive) base layer and the leakage current from the printed circuit element to the base is measured by the control circuit.

Abstract: A switching means detects a malfunction due to an open circuited or broken state of a temperature sensing element. The switching means overrides a normal control by the temperature sensing element of a heater, so the heater is de-energized by the switching means and possible uncontrolled, dangerous activation of the heater is prevented.

Abstract: The heater shutdown circuit is connected between an electric current source and a heating element in an electric heater and is operable to shut off the flow of current to the heating element when the heating element reaches a predetermined temperature and to maintain the flow of current shut off after the heating element cools to a temperature below the predetermined temperature. The heater shutdown circuit will maintain the electric current shut off until the heater shutdown circuit is disconnected from the current source for a predetermined period of time after which the heater shutdown circuit can be re-energized. The heater shutdown circuit includes a control circuit connected to the current source, a switching circuit coupled between the control circuit and the heating element, and a current sensing circuit coupled between the heating element and the junction between the control circuit and the switching circuit.

Abstract: A sealed thermostatic heater for use in a hair curling iron which uses a positive temperature coefficient (PTC) thermistor as a heat source together with a wire-wound heater, coated heater or ceramic heater.

Abstract: An arrangement of electrode for positive temperature coefficient semiconductor (PTCS) for use in heating and drying devices and the like, which PTCS is provided with a pair of electrode plates, each having a fork-like configuration with a plurality of branches or fingers in the form of strips extending forward from its base. The strips of both electrodes are disposed alternately on one of the opposing planes of the PTCS body. Each electrode has an extended portion serving as terminal which is bonded on the other plane of the PTCS body in such a manner that the terminal is not confronted, through the PTCS body, with any strips of opposite electrode.

Abstract: An energizing circuit for applying maximum electrical power to a heatable element having, at least, a high initial thermal lag. By sensing the resistance of the element, which varies as a function of its temperature, a control voltage is obtained which is used to vary the effectiveness of the heating current so as to provide rapid initial heating without the danger of burn-out. More specifically, the circuit is useful in energizing the glowplug of a model airplane engine.Current pulses are obtained from a storage battery which is connected in series with the glowplug and a semiconductor switch. The switch is turned on and off by a multivibrator to produce a series of current pulses. The duration of each "on" pulse is controlled by a bridge circuit which senses the resistance of the glowplug, which is a function of its temperature, and produces a control voltage which varies the timing of the multivibrator.

Abstract: A heating assembly having a protector for its sheet-type heating element, which is made from a sheet containing certain electroconductive fibrous or particulate materials such as carbon fibers. A detector element is formed on an intermediate resin layer having a negative temperature coefficient of resistivity, and two electrode layers are adhered to the opposite surfaces of the intermediate layer. The detector element is combined with or adhered to the sheet-type heating element, so that the whole surface of the heating element is completely covered thereby. A controlling circuit is connected between the detector element and the sheet type heating element.