Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/40—Heating elements having the shape of rods or tubes
  • H05B3/54—Heating elements having the shape of rods or tubes flexible
  • H05B3/56—Heating cables
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D23/00—Control of temperature
  • G05D23/19—Control of temperature characterised by the use of electric means
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D23/00—Control of temperature
  • G05D23/19—Control of temperature characterised by the use of electric means
  • G05D23/1906—Control of temperature characterised by the use of electric means using an analogue comparing device
  • G05D23/1909—Control of temperature characterised by the use of electric means using an analogue comparing device whose output amplitude can only take two discrete values
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D23/00—Control of temperature
  • G05D23/19—Control of temperature characterised by the use of electric means
  • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
  • G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B1/00—Details of electric heating devices
  • H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices

Definitions

• the present invention relates, in general, to an electromagnetic wave-free temperature control circuit and method for heating cables for bedding, which can perform heating and temperature detection, without causing the leakage of electromagnetic waves, in heating cables used for electrically heated bedding, such as electric blankets, electric papered floors or electric fomentation devices, or warmers, and, more particularly, to a temperature detection and control circuit, which can detect variation in the temperature impedance of an NTC thermistor in a three-wire NTC thermal cable and can control temperature using the detected variation in temperature impedance.
• a conventional heating cable, a temperature controller for heating the heating cable, and a temperature control method must use a separate temperature sensor for temperature detection. Additionally, a temperature contact switch or a bimetal electric contact point for preventing temperature from excessively increasing is separately provided, and thus temperature control is performed and an excessive increase in temperature is controlled. Since such a conventional scheme uses a separate temperature sensor and bimetal, it is difficult to use this scheme together with a method of blocking an electric field and a magnetic field. As a result, there is a problem in that the number of separate shields, other parts, and manufacturing processes for blocking an electric field and a magnetic field increases.
• an object of the present invention is to provide a temperature detection and control circuit, in which NTC thermistor resin, instead of a separately provided temperature sensor, is inserted between three heating wires while the three heating wires are used, thus simultaneously performing temperature detection and heating without separating the heating wires from the temperature sensor.
• Another object of the present invention is to provide a temperature detection and control circuit, which allows heating currents to flow in opposite directions by performing heating using two of three wires, thus canceling and blocking a magnetic field, and which allows the remaining one of the three wires to detect a temperature voltage based on an NTC thermistor through an interaction with the two wires for heating, thus making it possible to perform local temperature detection, as well as entire temperature detection, and to prevent the temperature from excessively increasing.
• a three- wire temperature detection and control circuit for electromagnetic shielding, the circuit being used while being connected to a heating cable, in which three wires are arranged with at least one NTC thermistor arranged therebetween, and, of the three wires of the heating cable, a first wire is used as a detection wire and a second wire and a third wire are connected to each other at ends thereof to allow heating current to make a U-turn and exit through the third wire when the heating current enters through the second wire, comprising a temperature signal voltage supply adjustment unit for controlling supply of a temperature signal voltage; a temperature detection unit for comparing a temperature signal voltage output between the first wire and the second wire and£>r between the first wire and the third wire with a reference voltage, and outputting a temperature control signal; a trigger coupling generation unit for generating a trigger signal and controlling a trigger operation; and a controlled rectifier connected to the trigger coupling generation unit, wherein a cathode
• a three- wire temperature detection and control circuit for electromagnetic shielding, the circuit being used while being connected to a heating cable, in which three wires are arranged with at least one NTC thermistor arranged therebetween, and, of the three wires of the heating cable, a first wire is used as a detection wire and a second wire and a third wire are connected to each other at ends thereof to allow heating current to make a U-turn and exit through the third wire when the heating current enters through the second wire, comprising a temperature signal voltage supply adjustment unit for controlling supply of a temperature signal voltage; a temperature detection unit for comparing a temperature signal voltage output between the first wire and the second wire and£>r between the first wire and the third wire with a reference voltage, and outputting a temperature control signal; a trigger coupling generation unit for generating a trigger signal and controlling a trigger operation; and a controlled rectifier connected to the trigger coupling generation unit, wherein an anode of the
• a three- wire temperature detection and control circuit for electromagnetic shielding, the circuit being used while being connected to a heating cable, in which three wires are arranged with at least one NTC thermistor arranged therebetween, and, of the three wires of the heating cable, a first wire is used as a detection wire and a second wire and a third wire are connected to each other at ends thereof to allow heating current to make a U-turn and exit through the third wire when the heating current enters through the second wire, the third wire being insulated from the second wire, comprising a temperature signal voltage supply adjustment unit for controlling supply of a temperature signal voltage; a temperature detection unit for comparing a temperature signal voltage output between the first wire and the second wire and£>r between the first wire and the third wire with a reference voltage, and outputting a temperature control signal; a trigger coupling generation unit for generating a trigger signal and controlling a trigger operation; and a controlled rectifier connected to the trigger
• a three- wire temperature detection and control circuit for electromagnetic shielding, the circuit being used while being connected to a heating cable, in which three wires are arranged with at least one NTC thermistor arranged therebetween, and, of the three wires of the heating cable, a first wire is used as a detection wire and a second wire and a third wire are connected to each other at ends thereof to allow heating current to make a U-turn and exit through the third wire when the heating current enters through the second wire, the third wire being insulated from the second wire, comprising a temperature signal voltage supply adjustment unit for controlling supply of a temperature signal voltage; a temperature detection unit for comparing a temperature signal voltage output between the first wire and the second wire and/br between the first wire and the third wire with a reference voltage, and outputting a temperature control signal; a trigger coupling generation unit for generating a trigger signal and controlling a trigger operation; and a controlled rectifier connected to the trigger coup
• the second wire and the third wire are configured such that a first end of either one of the second wire and the third wire is connected to a unidirectional rectifier, and heating current enters through the second wire through the unidirectional rectifier, makes a U-turn, and exits through the third wire.
• either one of the first wire and the third wire is used for shielding.
• the wire used for shielding is formed in a shape of a thin film and is located on an outer side compared to remaining two wires.
• the first wire is used for shielding, and only a first end of the first wire used for shielding is connected to the power source.
• the trigger coupling generation unit comprises a discharge trigger resistor, a charging amount control resistor, and a condenser
• the discharge trigger resistor is configured to turn on the controlled rectifier while the condenser is discharged
• the charging amount control resistor is configured to control a charging amount of the condenser
• the trigger coupling generation unit comprises a discharge trigger resistor, a charging amount control resistor, a condenser, a transistor and a charge/ discharge condenser
• the charge/discharge condenser is connected between the first wire and the second wire
• the transistor is connected between the charge/discharge condenser and the discharge trigger resistor
• the discharge trigger resistor is configured to turn on the controlled rectifier while the condenser is discharged
• the charging amount control resistor is configured to control a charging amount of the condenser.
• the temperature detection unit comprises a matching resistor for connecting between the first wire and the second wire, or between the first wire and the third wire.
• the temperature detection unit comprises a matching resistor for connecting between the first wire and the second wire.
• the temperature detection unit comprises a constant voltage diode connected to the first wire.
• the temperature detection unit further comprises a rectifying diode connected between the first wire and the constant voltage diode.
• the temperature detection unit comprises a rectifying diode connected to the first wire.
• the temperature detection unit comprises a photocoupler for connecting between the first wire and the second wire, or between the first wire and the third wire.
• the temperature detection unit comprises a photocoupler for connecting between the first wire and the second wire.
• the three-wire temperature detection and control circuit further comprises a pulse width adjustment generation circuit unit for adjusting and controlling a pulse width in a preset time-division manner when a signal voltage is applied to the temperature detection unit, wherein the trigger coupling generation unit receives a signal from the pulse width adjustment generation circuit unit to allow heating current to flow therethrough.
• the three-wire temperature detection and control circuit further comprises a pulse width adjustment generation circuit unit for adjusting and controlling a pulse width in a preset time-division manner when a signal voltage is applied to the temperature detection unit; and a switching unit for receiving a signal from the pulse width adjustment generation circuit unit and allowing heating current to flow therethrough.
• a pulse width adjustment generation circuit unit for adjusting and controlling a pulse width in a preset time-division manner when a signal voltage is applied to the temperature detection unit
• a switching unit for receiving a signal from the pulse width adjustment generation circuit unit and allowing heating current to flow therethrough.
• the temperature signal voltage supply adjustment unit comprises a variable resistor and a fixed resistor, which are connected in series.
• the trigger coupling generation unit comprises an overcurrent limiting resistor connected to the transistor, and the overcurrent limiting resistor is configured to adjust a discharging time of the charge/discharge condenser.
• the trigger coupling generation unit comprises a charging current limiting resistor; and a controlled rectifying device, wherein the charging current limiting resistor is connected between a common node of the discharge trigger resistor and the condenser, and an anode of the controlled rectifying device.
• the trigger coupling generation unit comprises a charging current limiting resistor; and a controlled rectifying device, wherein the transistor has a base and an emitter connected to the temperature detection unit, and the charging current limiting resistor is connected between a common node of the discharge trigger resistor and the condenser, and an anode of the controlled rectifying device.
• the three- wire temperature detection and control circuit further comprises a pulse width adjustment generation circuit unit for adjusting and controlling a pulse width in a preset time-division manner when a signal voltage is applied to the temperature detection unit, wherein the pulse width adjustment generation circuit unit is configured such that the pulse width is adjusted through a volume resistor, and thus heating power is controlled as the volume resistor is adjusted.
• the three-wire temperature detection and control circuit further comprises a pulse width adjustment generation circuit unit for adjusting and controlling a pulse width in a preset time-division manner when a signal voltage is applied to the temperature detection unit, wherein the pulse width adjustment generation circuit unit comprises a microcomputer control unit for controlling a pulse width by dividing a power synchronous frequency according to division conditions of a preset counter, and wherein the microcomputer control unit adjusts generation of a pulse and the width of the pulse by dividing the power synchronous frequency, and is configured to fix a temperature on a high-temperature side and to automatically adjust a temperature on a low-temperature side by performing pulse width control through a pulse width control oscillation circuit.
• the pulse width adjustment generation circuit unit comprises a microcomputer control unit for controlling a pulse width by dividing a power synchronous frequency according to division conditions of a preset counter, and wherein the microcomputer control unit adjusts generation of a pulse and the width of the pulse by dividing the power synchronous frequency, and is configured to fix a temperature on a high
• the pulse width adjustment generation circuit unit comprises a pho- tocoupler for insulation, and is configured to read a temperature signal voltage through the photocoupler or to trigger a gate of the controlled rectifier.
• the photocoupler is operated at a zero voltage crossing.
• the present invention is advantageous in that a simplified three-wire heating cable structure is employed to control temperature and prevent temperature from excessively increasing, using AC power supply voltage, without separately requiring both a temperature sensor and a device for preventing temperature from excessively increasing.
• the present invention is advantageous in that, since there is no need to use a separate temperature sensor and bimetal for preventing temperature from excessively increasing in electrically heated bedding or the like, electromagnetic environmental pollution, that is, electromagnetic waves, can be easily blocked, the construction of the present invention is simplified, and the manufacture thereof is facilitated, so that the manufacturing costs can be reduced, and the occurrence of inferior products can be decreased.
• FIG. 1 is a diagram showing the construction of a temperature detection and control circuit according to an embodiment of the present invention
• FIG. 2 is a diagram showing the construction of a temperature detection and control circuit according to another embodiment of the present invention.
• FIGS. 3 A to 3F are diagrams showing various embodiments of a three- wire heating cable used in the present invention.
• FIGS. 4A to 4F are diagrams showing respective sections of the heating cables of
• FIGS. 3A to 3F are identical to FIGS. 3A to 3F;
• FIGS. 5 A to 5D are diagrams showing operations among the three wires
• FIG. 6 is a diagram showing a circuit when temperature detection current is flowing
• FIG. 7 is a diagram showing another embodiment corresponding to the construction of FIG. 6;
• FIG. 8 is a diagram showing a further embodiment corresponding to the construction of FIG. 6;
• FIG. 9 is a diagram showing yet another embodiment corresponding to the construction of FIG. 6;
• FIG. 10 is a diagram showing still another embodiment corresponding to the construction of FIG. 6;
• FIGS. 11 to 15 are diagrams showing other embodiments corresponding to the constructions of FIGS. 6 to 10;
• FIG. 16 is a diagram showing a circuit when heating current is flowing
• FIG. 17 is a diagram showing another circuit when heating current is flowing
• FIG. 18 is a diagram showing the construction of FIG. 1 in detail
• FIG. 19 is a diagram showing another embodiment corresponding to the construction of FIG. 18;
• FIGS. 20 and 21 are diagrams showing other embodiments corresponding to the constructions of FIGS. 18 and 19;
• FIG. 22 is a diagram showing an embodiment in which a first wire is connected only in one direction
• FIG. 23 is a waveform diagram showing the operation of the circuit of FIG. 18;
• FIG. 24 is a diagram showing an embodiment in which the circuit of FIG. 18 is constructed in a reverse phase
• FIG. 25 is a diagram showing another embodiment corresponding to the construction of FIG. 24;
• FIG. 26 is a waveform diagram showing the operation of the circuit of FIG. 24;
• FIG. 27 is a diagram showing another embodiment corresponding to the construction of FIG. 1;
• FIG. 28 is a diagram showing another embodiment corresponding to the construction of FIG. 27;
• FIG. 29 is a diagram showing an embodiment in which the circuit of FIG. 27 is constructed in a reverse phase;
• FIG. 30 is a diagram showing another embodiment corresponding to the construction of FIG. 28;
• FIG. 31 is a diagram showing a temperature detection and control circuit according to a further embodiment of the present invention.
• FIG. 32 is a diagram showing the construction of FIG. 31 in detail
• FIG. 33 is a waveform diagram showing the operation of a high-temperature side in the circuit of FIG. 32;
• FIG. 34 is a waveform diagram showing the operation of a low-temperature side in the circuit of FIG. 32.
• FIG. 35 is a diagram showing a temperature detection and control circuit using a photocoupler according to yet another embodiment of the present invention. Best Mode for Carrying Out the Invention
• FIG. 1 is a diagram showing the construction of a temperature detection and control circuit according to an embodiment of the present invention.
• a fuse (not shown) and a power switch (not shown) are connected to a power source, and a temperature signal voltage supply adjustment unit 100 and a trigger coupling generation unit 200 are connected in parallel with the power source.
• a controlled rectifier 30 is connected between the trigger coupling generation unit
• the controlled rectifier 30 is mainly implemented using a Silicon Controlled Rectifier (SCR), and the trigger coupling generation unit 200 is connected to the gate of the SCR.
• SCR Silicon Controlled Rectifier
• Negative Temperature Coefficient (NTC) thermistors plastic nylon NTC temperature sensors 14 may be arranged between the first and second wires 11 and 12 and between the first and third wires 11 and 13.
• NTC thermistor plastic nylon NTC temperature sensors
• the second and third wires 12 and 13 may be insulated.
• An NTC thermistor the resistance of which decreases with an increase in temperature, reaches a preset temperature control point when the second or third wire 12 or 13 is locally overheated, or when a relevant NTC thermistor 14 is broken and the first wire 11 is then short-circuited to the second or third wire 12 or 13.
• the impedance of the NTC thermistor 14 rapidly decreases, so that voltage is blocked by the NTC thermistor 14 and makes a U-turn, and thus a signal voltage does not reach a temperature detection unit, or reaches the temperature detection unit while being attenuated.
• the controlled rectifier (SCR) 30 is turned off, and does not generate a trigger signal, thus stopping the supply of heating current.
• Coatings and shields are formed on the outer side of the wires. According to the circumstances, shields or coatings may be added or removed.
• the second wire 12 and the third wire 13 are configured such that the second ends thereof are connected to each other, and such that, when signals enter through the second wire 12, the signals make a U-turn and exit through the third wire 13, or the signals flow in the reverse direction.
• the first ends of the first wire 11 and the second wire 12 or the first ends of the first wire 11 and the third wire 13 are connected to the temperature detection unit 300.
• the temperature detection unit 300 is shown to be connected to the second wire 12.
• the temperature detection unit 300 includes or is connected to an NTC thermistor, and includes a resistor 310 therein as a temperature detection resistor or a gate bias resistor.
• the temperature detection unit 300 together with the NTC thermistors 14 of the heating cable 10, detects a temperature signal between the first wire 11 and the second wire 12, or both a temperature signal between the first wire 11 and the second wire 12 and a temperature signal between the first wire 11 and the third wire 13.
• the temperature detection unit 300 is connected to the trigger coupling generation unit 200 and is configured to transmit the detected temperature signal to the trigger coupling generation unit 200.
• the operation of the temperature signal detection and output method is performed in such a way that, when AC power supply voltage is connected in series with the first wire 11 of the heating cable 10 through a resistor 110 and a variable resistor 120, a temperature signal AC current flows to the second and third wires, which are heating wires, through the resistor 110, the variable resistor 120, the NTCl thermistor between the first and second wires 11 and 12 connected in parallel, and the NTC2 thermistor between the first and third wires 11 and 13.
• NTCl thermistor between the first wire 11 and the second wire 12 and the NTC2 thermistor between the first wire 11 and the third wire 13 are decreased.
• the temperature signal AC current values flowing through the NTCl and NTC2 thermistors are proportionally decreased, so that AC voltage values between the first and second wires and between the first and third wires are proportionally decreased, similar to the current values. Accordingly, the temperature signal voltage is output through the selection between the first wire 11 and the second wire 12 or between the first wire 11 and the third wire 13.
• the output temperature signal value is output in the form of a value obtained when the NTCl thermistor and the NTC2 thermistor are connected in parallel.
• the temperature detection unit 300 is a part for detecting a temperature signal voltage generated by the temperature signal voltage supply adjustment unit 100, and comparing the temperature signal voltage with a reference voltage. During a positive (+) half period for temperature detection, the temperature detection unit 300 compares the detected temperature signal voltage with the reference voltage, and turns on the SCR (420 of FIG. 18) of the trigger coupling generation unit 200 when the temperature signal voltage is higher than the reference voltage. When the SCR 420 is turned on, current passes through the charging amount control resistor 230 of the trigger coupling generation unit 200 and charges a condenser 220, and the charging potential of the condenser 220 is determined by the resistance value of a charging current limiting resistor 410.
• the controlled rectifier 30 may also be connected in a reverse direction as well as a forward direction.
• the accompanying claims 1 and 3 indicate a connection relationship when the controlled rectifier 30 is connected in a forward direction
• the accompanying claims 2 and 4 indicate a connection relationship when the controlled rectifier 30 is connected in a reverse direction. Such a connection relationship can be selectively applied, and detailed embodiments related to the reverse connection are shown in FIGS. 24, 25, 29, 30 and 35.
• FIG. 2 is a diagram showing the construction of a temperature detection and control circuit according to another embodiment of the present invention.
• the construction of claims 1 and 4 may be implemented, as in the case of this em- bodiment. That is, a trigger coupling generation unit 200 and a controlled rectifier 30 may be arranged on a power source side in the same direction as a temperature signal voltage supply adjustment unit 100.
• the difference between the circuits of FIGS. 1 and 2 manifests itself in an electric field shielding ratio when a first or third wire is used as a shield wire.
• the electric field shielding ratio is low, whereas, when a construction is implemented, as shown in FIG. 2, the electric field shielding ratio can be increased.
• the third wire 13 is used as a shield wire in the circuit construction of FIG. 1, it is difficult to completely block an electric field.
• a condenser 220 functions to allow short circuit current to flow into a power fuse and to cut the power fuse when the control rectifying unit 30 is short- circuited.
• a unidirectional rectifier 20a performs the same operation as a U-turn rectifying diode, and is a directional diode for separating heating current and temperature detection current. Only heating current can flow through the second and third wires through the unidirectional rectifier 20a.
• either the first wire 11 or the third wire 13 can be used as a shield wire.
• the third wire 13 may be used as a shield wire
• the first wire 11 may be used as a shield wire.
• the third wire 13 is used as a shield wire in FIG. 2
• a magnetic field-free heating operation is possible, but an electric field cannot be blocked.
• the second wire 12 is used as a shield wire in FIG. 2, the same electric field shielding ratio as that of the construction of FIG. 1 can be obtained.
• FIGS. 3A to 3F are diagrams showing various embodiments of a three-wire heating cable used in the present invention
• FIGS. 4A to 4F are diagrams showing respective sections of the heating cables of FIGS. 3A to 3F.
• FIGS. 3A and 4A illustrate a heating cable in which a first wire 11 is wound around a core thread 11a made of synthetic resin, an NTC thermistor 14 is wound around the outer circumference of the first wire 11, and a second wire 12 and a third wire 13 are wound around the outer circumference of the NTC thermistor 14 in parallel so that the second wire 12 and the third wire 13 do not come into contact with each other.
• the second wire 12 is spaced apart from the third wire 13, and only the NTC thermistor 14 comes into contact with both the second and third wires 12 and 13.
• either the second wire 12 or the third wire 13 may be coated and insulated. This will be described in detail later with reference to FIGS. 27 to 30.
• the NTC thermistor 14 is arranged between the first wire 11, and the second and third wires 12 and 13 to come into contact with the wires. Referring to the sections thereof, the first wire 11, the second wire 12 and the third wire 13 are arranged in a triangular configuration around the NTC thermistor 14. In principle, an NTC thermistor is also connected between the second wire 12 and the third wire 13, but an insulator 15 may be preferably provided according to the circumstances, thus preventing the second wire 12 and the third wire 13 from being short-circuited to each other.
• FIGS. 3A and 4A illustrate the embodiment in which the core thread 1 Ia made of synthetic resin is arranged at the center, the first wire 11 is spirally wound around the core thread l la, the NTC thermistor 14 is wound around the outer circumference of the first wire 11, and the second wire 12 and the third wire 13 are spirally wound around the outer circumference of the NTC thermistor 14 and are spaced apart from each other by a predetermined interval.
• wire winding technology has not been sufficiently developed, and thus it was very difficult to arrange two wires on the same layer while allowing the wires to be spaced apart from each other, as shown in the drawings.
• FIGS. 3B and 4B illustrate an embodiment approximately similar to FIGS. 3A and
• a first wire is not wound around a core thread and is independently arranged at the center of a heating cable.
• FIGS. 3C and 4C illustrate an embodiment in which each of first, second and third wires 11, 12 and 13 is enclosed by an NTC thermistor 14. According to the circumstances, either one of the second wire 12 and the third wire 13 may be coated with an insulator made of enamel or synthetic resin.
• FIGS. 3D and 4D illustrate an embodiment in which first, second and third wires 11,
• the above embodiments are characterized in that the first wire 11, used for temperature detection, and the second and third wires 12 and 13, used for allowing current to make a U-turn and to exit therethrough, are provided, and the NTC thermistor 14 is arranged between the wires.
• the second wire 12 and the third wire 13 should not come into contact with each other at the center portions thereof and either one of the second wire 12 and the third wire 13 may be coated with an insulator.
• FIGS. 3E and 4E illustrate an embodiment in which a first wire 11 is wound around the outer circumference of a core thread 1 Ia, a second wire 12 only is wound around the outer circumference of the NTC thermistor 14, a second coating 12a is wound around the outer circumference of the second wire 12, and a third wire 13 is made of thin film-shaped conductive metal material and encloses the second coating 12a.
• This can be used in the construction of FIG. 1, and the second coating 12a may be implemented using an NTC thermistor or may be made of insulating material.
• FIGS. 3F and 4F illustrate an embodiment in which the locations of the first wire 11 and the third wire 13 are changed in the construction of 3E and 4E, and which is used in the construction of FIG. 2.
• FIGS. 5A to 5D are diagrams showing operations among the three wires.
• a first wire 11, a second wire 12 and a third wire 13 form a triangular configuration
• respective NTC thermistors 14 are arranged between the first wire 11 for temperature detection and the second wire 12 and between the first wire 11 and the third wire 13. Accordingly, as shown in the drawings, variation in a temperature signal value relative to variation in impedance appears in the relationship with NTCl and NTC2 thermistors. Such a temperature signal value is calculated and detected by a temperature detection unit 300 as parallel values.
• the third wire 13 When the third wire 13 is coated with an insulating coating, only variation in the impedance of the NTCl thermistor between the first wire 11 and the second wire 12 is detected. Since the internal electric resistance values of respective wires are much lower than the impedance of the NTC thermistor, they are regarded as approximately '0'. As the ends of the second wire 12 and the third wire 13 are connected to each other, NTCl and NTC2 thermistors are handled as parallel components.
• the temperature detection unit 300 compares a detection signal voltage corresponding to temperature detection current at the first wire 11 with a reference voltage. According to the characteristics of the NTC thermistor 14, as temperature is high, impedance becomes low. In this case, the detection signal voltage becomes lower than the reference voltage. When the temperature signal voltage is lower than the reference voltage, a trigger signal is not output, so that the controlled rectifier 30 is not operated, and thus heating is stopped. Therefore, the temperature detection unit 300 functions to continue to perform a heating operation only when the temperature is low.
• the first wire 11 may be used as a shield wire to enclose both the second wire 12 and the third wire 13.
• the third wire 13 may be used as a shield wire to enclose both the first wire 11 and the second wire 12.
• FIG. 6 is a diagram showing a circuit when temperature detection current is flowing.
• the flows of temperature detection current and trigger generation current, input during the positive (+) half period of power are illustrated.
• the temperature detection current passes through the resistor 110 and the variable resistor 120 of a temperature signal voltage supply adjustment unit 100, and then flows to the first end of the first wire 11.
• the trigger generation current passes through the charging amount control resistor 230 and the condenser 220 of the trigger coupling generation unit 200, and, at this time, the condenser 220 is charged.
• a matching resistor 310 is used for mutual impedance matching (scale span matching) between the resistor 310 and the temperature detection unit 300, and is used to represent a detection load.
• a temperature signal voltage detected from the first wire 11 is compared to a reference voltage set by the temperature signal voltage supply adjustment unit 100.
• the temperature detection unit 300 turns on the controlled rectifier 30.
• the controlled rectifier (SCR) 30 is turned on, current charges the condenser 220.
• a heating operation is performed during the subsequent negative (-) half period.
• the heating operation is performed in such a way that, when charges stored in the condenser 220 trigger the gate of the controlled rectifier 30, and the controlled rectifier 30 is turned on, current enters through either one of the second and third wires, makes a U-turn, and exits through the remaining one thereof. Accordingly, the heating cable 10 is heated in a magnetic field-free state, which will be described in detail later with reference to FIG. 10.
• FIG. 7 is a diagram showing another embodiment of the construction of FIG. 6.
• FIGS. 8 to 10 are diagrams showing other embodiments of the construction of FIG. 6.
• a constant voltage diode 320 is further connected to the second end of a first wire 11.
• the constant voltage diode 320 outputs variation in all NTC values. Fbwever, when the constant voltage diode 320 is further provided, NTC values below a constant voltage value are "0", and only variation in NTC values above the constant voltage value appears.
• the constant voltage diode 320 is required in order to compare NTC values with the constant voltage and to read values above the constant voltage as "HIGH” and values below the constant voltage as "LOW".
• the constant voltage diode 320 may be replaced with a unidirectional rectifying diode 340, as shown in FIG. 9.
• a rectifying diode 330 is additionally arranged between one end of the first wire 11 and the constant voltage diode 320 and is configured to output a temperature signal in one direction. Accordingly, the rectifying diode 330 functions to protect a circuit in a subsequent stage when a reverse voltage is generated.
• a photocoupler 350 is provided, thus realizing electrical insulation.
• Current flowing from the temperature signal voltage supply adjustment unit 100 is divided and separately flows to NTC thermistors and a photocoupler 350.
• the impedance values thereof are decreased, and current, which must flow into the photocoupler 350, flows into the NTC thermistors 14, thus changing the illuminance value of the photocoupler 350.
• the current value of the photocoupler changes in proportion to variation in the illuminance value, the flow of heating current is adjusted.
• FIGS. 11 to 15 are diagrams showing other embodiments corresponding to the constructions of FIGS. 6 to 10.
• the constructions and operations of FIGS. 11 to 15 correspond to those of FIGS. 6 to 10.
• the operations of FIGS. 11 to 15 are identical to those of FIGS. 6 to 10, except that a first wire 11 is used as a shield wire. Since the first wire 11 is grounded on a power source side while performing a shield function, the first wire 11 functions to ground charges, leaked to an external side, and a formed electric field, thus canceling the charges and the electric field.
• FIGS. 16 and 17 are diagrams showing a circuit when heating current is flowing
• FIG. 18 is a diagram showing the construction of FIG. 1 in detail
• FIG. 19 is a diagram showing another embodiment corresponding to the construction of FIG. 18.
• FIGS. 20 and 21 are diagrams showing other embodiments corresponding to the constructions of FIGS. 18 and 19, respectively.
• the trigger coupling generation unit 200 having the above function, is implemented in the prior art so that a rectifying diode is connected in parallel with a condenser.
• the present invention performs the same function only using a simple structure through a discharge trigger resistor 210, a charging amount control resistor 230, and a charging/discharging of the condenser 220 connected therebetween, without using a rectifying diode.
• the trigger coupling generation unit 200 functions to reduce the number of parts and the number of places at which heat is generated.
• the charging amount control resistor 230 is connected both to the power source and to the gate of the controlled rectifier 30, and the cathode of the controlled rectifier 30 is connected to the power source.
• the anode of the controlled rectifier 30 is connected to the end of the second wire 12, and the condenser 220 is connected both to the gate of the controlled rectifier 30 and to the discharge trigger resistor 210.
• the trigger coupling generation unit 200 includes a charging current limiting resistor 410 and an SCR 420, which are connected in series with the discharge trigger resistor 210.
• the controlled rectifier 30 is constructed such that the cathode thereof is connected to an AC power terminal and the anode thereof is connected to a reference point on the temperature signal input side of the temperature detection unit. This reference point is preferably connected in series with the second and third wires required for the heating of the heating cable.
• the controlled rectifier 30 may be constructed such that the anode thereof is connected to the AC power terminal and the cathode thereof is connected to the second or third wire.
• a heating operation is performed in such a way that, when the controlled rectifier 30 is turned on in response to a trigger signal output from the trigger coupling generation unit 200, heating current flows through the third wire 13 and the second wire 12, connected in series with the power source, and thus the heating cable is heated.
• temperature detection current and heating current can be designated to flow in opposite directions for each half- wave period.
• the trigger coupling generation unit 200 can perform this function through the condenser 220, the discharge trigger resistor 210 and the charging amount control resistor 230, without requiring a separate rectifier.
• the temperature detection unit 300 is shown to include a matching resistor 310, but includes all portions required to detect the NTC thermistor 14.
• a rectifier 20 may be connected between the second ends of the second wire 12 and the third wire 13.
• the rectifier 20 functions as a safety device for preventing reverse voltage and functions to cut a power fuse by easily detecting the reverse voltage.
• the same method as the above method can be applied to heating cables, through which current flows only in one direction, on the basis of the same principle, in addition to the above-described magnetic field-free heating cable, that is, the heating cable in which heating wires are configured as dual wires corresponding to inner and outer sides to allow current to make a U-turn and flow therethrough.
• the heating cable includes only one wire for heating.
• the heating cable includes one first wire for a sensor, and one wire for heating, in which second and third wires, connected in parallel without forming a U-turn structure, are included together.
• temperature detection and heating can be performed for each half- wave period through the charging and discharging operation of the trigger coupling generation unit 200.
• This circuit is intended to adjust temperature by turning on or off heating power in a zero-cross switching manner using the temperature signal voltage described with reference to FIG. 6.
• the resistance of the variable resistor 120 is set as a resistance corresponding to a low voltage side, and a temperature signal voltage is decreased, the input voltage value of a controlled rectifying device (SCR) 420 is decreased, and the SCR 420 is not turned on, so that the condenser 220 is not charged, and the controlled rectifier 30 is not turned on, thus interrupting the supply of heating current.
• SCR controlled rectifying device
• FIGS. 19 and 21 are diagrams showing other embodiments corresponding to the constructions of FIGS. 18 and 20. Referring to FIGS.
• a constant voltage zener diode 320 is additionally provided at the second end of a first wire 11 or a second wire 12, and a rectifying diode 330 is additionally arranged between the end of the first wire 11 or the second wire 12 and the constant voltage diode 320, so that a temperature signal is output in one direction.
• the constant voltage diode 320 outputs variation in all NTC values.
• NTC values below a constant voltage value are "0", and only variation in NTC values above the constant voltage value appears.
• the constant voltage diode 320 is required in order to compare NTC values with the constant voltage and to read values above the constant voltage as "HIGH” and values below the constant voltage as "LOW".
• FIG. 22 is a diagram showing an embodiment in which a first wire is connected only in one direction.
• the first wire 11 for shielding may be configured such that only one end thereof is connected to a power source or a second wire 12, and any connection to other portions of the first wire is not established.
• the number of terminals 17 connected between the heating cable and the temperature detection and control circuit can be reduced to a minimum of 3, so that production assembly can be facilitated because of the reduction of connection portions, and the use of wires can be reduced, thus increasing economical efficiency such as the reduction of costs.
• FIG. 23 is a waveform diagram showing the operation of the circuit of FIG. 18.
• a temperature signal voltage input to the gate of the SCR 420 of the trigger coupling generation unit 200 indicates the waveform of 'b'.
• a preset value a horizontal dotted line
• conduction current is output from the anode of the SCR
• conduction current is not output (refer to 'c')
• the potential of the condenser 220 is changed, as shown in 'd'.
• heating current may be input as in the case of an ON operation, or may be interrupted as in the case of an OFF operation.
• FIG. 24 is a diagram showing an embodiment in which the circuit of FIG. 18 is configured in a reverse phase
• FIG. 25 is a diagram showing another embodiment of the construction of FIG. 24.
• FIGS. 24 and 25 illustrate circuits configured by slightly modifying the circuits of FIGS. 18 and 19. These circuits correspond to claims 2 and 4, respectively.
• a trigger coupling generation unit 200 includes a discharge trigger resistor 210, a charging amount control resistor 230, a condenser 220, a transistor 240, a charge/discharge condenser 260, and an overcurrent limiting resistor 250.
• a temperature signal voltage flowing at a positive (+) phase angle, flows at a negative (-) phase angle.
• both the transistor 240 and the overcurrent limiting resistor 250 are provided.
• a heating voltage is a positive voltage, and is operated at a reverse phase.
• Such a circuit performs the same temperature adjustment method as the above-described circuit, except for the difference that only the phase values are reversed.
• a temperature signal is detected as a negative (-) signal voltage
• a PNP transistor is used.
• the input thereof must be a positive (+) signal, but, in practice, a negative (-) signal is applied to the SCR, so that the problem of switching a phase from (-) to (+) occurs, and thus the SCR is not used.
• the overcurrent limiting resistor 250 is intended to control the discharging time of the charge/discharge condenser 260, and functions to increase a portion, indicated by oblique lines in 'b', which will be described in FIG. 26, along a time axis.
• the overcurrent limiting resistor is used both for impedance matching and for overcurrent limiting, as in the case of the above-described resistor 310.
• the overcurrent limiting resistor may also be used for protection when static electricity occurs in the heating cable, and then a high voltage is generated.
• the transistor 240 is used to determine whether to discharge the condenser 220 in response to a temperature signal.
• FIG. 26 is a waveform diagram showing the operation of the circuit of FIG. 24.
• FIG. 27 is a diagram showing another embodiment corresponding to the construction of FIG. 1 in detail
• FIGS. 28 to 30 are diagrams showing other embodiments of the construction of FIG. 27. Referring to FIGS. 27 to 30, the constructions thereof are the same as those of the above-described circuits, except for a heating cable 10.
• a third wire 13 is coated with an insulating layer 15, so that only a second wire 12 comes into contact with a first wire 11 through an NTC thermistor 14, and does not come into contact with the third wire 13.
• NTCl is calculated, without performing calculation by combining the values of NTCl and NTC2 in parallel, as in the case of the above description.
• FIGS. 31 and 32 are diagrams showing other embodiments of the present invention.
• a pulse generation timer IC for controlling power in a time-division manner is additionally provided in the control circuit.
• temperature control based only on an average temperature signal value may cause the surface temperature of the heating cable 10 to be unequal in the low-temperature portion of the heating cable 10 when the heat insulation has not been uniformly applied to the entire heating cable 10. Therefore, in order to compensate for this inequality, the low-temperature portion is heated at a fixed power ratio.
• temperature control for the high- temperature portion of the heating cable 10 is performed so as to control overheating and an excessive increase in temperature by fixing power to an existing temperature signal voltage
• temperature control for the low-temperature portion thereof is performed so as to control overheating and an excessive increase in temperature by adjusting power in a time-division manner.
• Such a time division method is achieved using a pulse width oscillation circuit, and is configured to perform control by fixing an oscillation frequency and adjusting the duty ratio of a pulse width. This can be easily implemented using a microcomputer chip or a timer IC.
• a pulse width adjustment generation circuit unit 600 is configured such that power is applied to a power supply unit composed of a resistor 621, a rectifying diode 622, a DC smoothing condenser 624, and a zener diode 623, and then circuit power is generated, and such that a microcomputer control unit (IC-lm555) 620, condensers 630 and 631, resistors 625, 627 and 629, and a volume resistor 610 are provided, thus supplying power to the trigger coupling generation unit 200.
• IC-lm555 microcomputer control unit
• the pulse width adjustment generation circuit unit 600 is implemented using a well- known timer (IC-lm555) oscillation circuit.
• IC-lm555 timer
• a pulse width adjustment method performed by the oscillation circuit (IC-lm555) is related to well-known commercialized products, and thus a description of the operation thereof is omitted.
• An oscillation period is determined by the condenser 631, the resistors 625, 627 and 629, and the volume resistor 610, and the adjustment of a pulse width is performed by the volume resistor 610 or by controlling the charging/discharging direction and time of diodes 626 and 628.
• the duty ratio of the pulse width can be changed within the range from less than 10% to more than 90%.
• the pulse width adjustment generation circuit unit 600 is connected to an ON/OFF switching unit 500, and the temperature signal voltage supply adjustment unit 100 is fixed to a high temperature side by removing the variable resistor 120.
• the pulse width adjustment generation circuit unit 600 is coupled to the switching unit 500 to switch a temperature signal output value to HIGH or LOW in a time-division manner, the SCR 420 is turned on or off in response to the synchronization of time division, and thus the heating cable 10 is heated.
• the pulse width adjustment generation circuit unit 600 is coupled to and combined with the temperature detection unit 300 through the coupling diode 510.
• the anode of the coupling diode 510 is connected to the bias resistor 310 of the gate of the controlled rectifying device 420, and the cathode thereof is connected to the output of the pulse width adjustment generation circuit unit 600.
• a pulse signal voltage, output in a time-division manner is low, a control signal voltage at both ends of the bias resistor 310 becomes a low level through the coupling diode 510, and thus controls the ON operation of the controlled rectifying device 420.
• FIG. 33 is a waveform diagram showing the actual operation of the temperature control circuit according to the present invention. In particular, the operation waveforms of the high-temperature side of the circuit of FIG. 32 are shown.
• FIG. 33 when AC power is input, as shown in 'a', voltage loss or the like is caused depending on variation in the impedance between the first wire 11 and the second wire 12 or between the first wire 11 and the third wire 13 during an initial half- wave period.
• the magnitude of a temperature signal voltage input to the gate of the SCR 420 is equal to or greater than a preset value, the anode current of the SCR 420 is generated, as shown in 'c'.
• FIG. 34 is a waveform diagram showing the operation of the low-temperature side of the circuit of FIG. 32.
• (a) indicates the input of AC power
• (b) and (f) respectively indicate time-division pulse oscillation waveforms in the cases where the duty ratios of heating current are set to 10%, 50%, and 100%, per repetition period
• (c) and (e) respectively indicate the states of heating currents applied at respective duty ratios.
• Heating time is increased or decreased depending on the duty ratio, and thus heating intensity can be adjusted.
• the adjustment of this duty ratio can be performed by selecting a duty ratio through a volume resistor, utilizing a resistor and the charging/ discharging time of a condenser, or controlling pulse generation or pulse width through a microcomputer.
• the heater surface temperature density of a heating cable which warms a human body by directly heating the human body in bedding or the like, is defined to be below a maximum of 12O 0 C according to safety rules or standards, and, in practice, it is prescribed to be below 100 0 C on average. Accordingly, due thereto, heater resistance surface power corresponding to the case where the surface temperature of the heating cable is less than 12O 0 C is previously set.
• the surface temperature density of the heating cable has a proportional relationship which is identical to the electric power consumption density of the surfaces of the heating cable. Therefore, there is no need to control a heater surface temperature by supplying heating power while measuring temperature using a separate temperature sensor, and it is possible to control the surface temperature of the heating cable by dividing the surface power density into time slots.
• FIG. 35 is a diagram showing another embodiment using a photocoupler.
• the pulse width signal voltage of a pulse width adjustment generation circuit unit 600 operates a photocoupler 640, and then turns on the controlled rectifier 30, half- wave heating current flows through a second wire 12 and a third wire 13, and thus the wires are heated. That is, when temperature signal voltages are output in an electric insulation state using photocouplers, and are transmitted to a temperature control circuit implemented using a microcomputer chip or the like, such temperature signals are analyzed and output through the gate of the controlled rectifier 30, and thus the temperature of the heating cable 10 is automatically adjusted. It can be seen that, when the temperature signal voltages are output in an insulation state using photo- couplers and are used thereby, the possibility of the application thereof can be greatly widened.
• a photocoupler 640 is connected to a light emitting diode (LED) 350 on an input side, and the LED 350 is turned on depending on the pulse width of the output of the pulse width adjustment generation circuit unit 600, so that the gate of the controlled rectifier 30 is triggered and the controlled rectifier 30 is turned on.
• the photocoupler 640 may be implemented using MOC3061 for triggering the controlled rectifier 30 at a zero voltage crossing, or using a phase control photocoupler, such as MOC3021.
• a surface electric field shielding unit (not shown) is separately provided on a heating cable, so that a ground lighting indicator, connected to one end of any one of the grounded wires of the heating cable 10, and an examination test terminal (not shown), configured to block the surface electric field of the heating cable by setting the ground lighting indicator (not shown) to an OFF location, may be provided.
• the ground lighting indicator includes a resistor (not shown) and a neon tube (not shown), which are connected in series.
• an overcurrent prevention device may be additionally provided in the above circuit.
• the operation of the overcurrent prevention device is described below.
• the overcurrent prevention device is configured to sense that the controlled rectifier 30 is short-circuited and that a reverse overcurrent is flowing through the heating cable 10, and to shut off the flow of the overcurrent.
• the overcurrent prevention device includes a reverse detection rectifier 20.
• the rectifier 20 is connected in parallel with the second wire 12 in the reverse direction of heating current flowing through the third wire 13.
• the controlled rectifier 30 When the controlled rectifier 30 is short-circuited, reverse overcurrent flows through the rectifier 20. When this overcurrent flows, the overcurrent cuts a fuse, thus protecting the circuit from overheating.
• the claims of the present patent include a construction in which each of three wires is coated with NTC thermistor resin, and one of the three wires is arbitrarily selected and is used as a temperature signal detection wire.
• the claims of the present patent includes a temperature signal voltage output method for an apparatus for preventing temperature from excessively increasing, in which, when an arbitrary local portion of the second wire or the third wire is locally overheated at the time of heating the second and third wires, the impedance of the NTC thermistor between the first and second wires or between the first and third wires decreases, and the heating currents of the second and third wires are controlled using the reduction of a temperature signal voltage passed through the NTC thermistor.
• the present invention is advantageous in that a simplified three- wire heating cable structure is employed to control temperature and prevent temperature from excessively increasing, using AC power supply voltage, without separately requiring both a temperature sensor and a device for preventing temperature from excessively increasing.
• the present invention is advantageous in that, since there is no need to use a separate temperature sensor and bimetal for preventing temperature from excessively increasing in electrically heated bedding or the like, electromagnetic environmental pollution, that is, electromagnetic waves, can be easily blocked, the construction of the present invention is simplified, and the manufacture thereof is facilitated, so that the manufacturing costs can be reduced, and the occurrence of inferior products can be decreased.

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• 2007
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