US3360693A - Switching circuit for an electrically heated blanket - Google Patents

Switching circuit for an electrically heated blanket Download PDF

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Publication number
US3360693A
US3360693A US449463A US44946365A US3360693A US 3360693 A US3360693 A US 3360693A US 449463 A US449463 A US 449463A US 44946365 A US44946365 A US 44946365A US 3360693 A US3360693 A US 3360693A
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US
United States
Prior art keywords
circuit
switching circuit
resistor
electrically heated
collector
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US449463A
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English (en)
Inventor
August E F Fickweiler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
INDOHEEM NV
Original Assignee
INDOHEEM NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by INDOHEEM NV filed Critical INDOHEEM NV
Application granted granted Critical
Publication of US3360693A publication Critical patent/US3360693A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • G05D23/30—Automatic controllers with an auxiliary heating device affecting the sensing element, e.g. for anticipating change of temperature
    • G05D23/303—Automatic controllers with an auxiliary heating device affecting the sensing element, e.g. for anticipating change of temperature using a sensing element having a resistance varying with temperature, e.g. thermistor
    • 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

Definitions

  • the invention relates to a switching circuit for an electrically heated blanket, comprising one or more resistors with negative temperature coeflicient which are arranged in the blanket and which serve as temperature sensors and control the switching circuit.
  • the heating circuit is switched on as soon as the temperature falls so far, that the resistance of the resistor(s) with negative temperature coefiicient rises above a predetermined value, whereas the heating circuit is disconnected as soon as the temperature has risen so far, that the resistance falls below a predetermined value.
  • the switching circuit is through a flexible cord connected with the blanket and the resistor(s) with negative temperature coefficient provided therein, the risk of a short-circuit or interruption of these resistors is not imaginary.
  • a short-circuit is not hazardous, since in that case the heating circuit is switched otf.
  • An interruption however, keeps the heating circuit switched on indefinitely, regardless of the blanket temperature, so that the blanket can be scorched or can even cause injuries to the user.
  • the heating element is connected to the supply source through a normally open contact of a relay, the coil of which is connecte'd in the collector circuit of a control transistor, the base electrode of which is through a conventional resistor connected to the collector supply line and is through the resistor(s) with negative temperature coefiicient connected to the emitter supply line, whilst the switching circuit is further provided with a guard transistor, the base electrode of which is connected to the base electrode of the control transistor, whilst its emitter electrode is connected to the collector electrode of the control transistor and its collector electrode is connected to the collector supply line.
  • the guard transistor During normal operation the guard transistor has a negligible influence on the control circuit, but at the occurrence 01f an interruption of the resistors with negative temperature coeflicient, the voltage across the conven tional resistor in the base circuit of the control and guard transistors becomes so small, that the guard transistor short-circuits the relay coil and thereby disconnects the heating circuit, although the control transistor carries the maximum current.
  • the invention is further elucidated below with reference to the drawing, which shows a circuit diagram of an embodiment of a switching circuit according to the invention.
  • the heating element 1 is through the normally open contact of a relay 2 connected to the supply terminals 3.
  • the coil of the relay 2 is connected in the collector circuit of a control transistor 4, the base electrode of which is through a conventional resistor 5 connected to the collector supply line 6 and is through the resistor(s) with negative temperature coefficient 7 connected to the emitter supply line 8.
  • a guard transistor 9 is with its emitter electrode and collector electrode connected to the relay coil and is with its base electrode connected to the base electrode of the control transistor 4.
  • control transistor 4 is via its emitter electrode and through a common emitter resistor 10 coupled with a further transistor 11, provided with base resistors 12 and 13 and a collector resistor 14.
  • a common emitter resistor 10 coupled with a further transistor 11, provided with base resistors 12 and 13 and a collector resistor 14.
  • the temperature at which the beating circuit is switched on and switched off can be adjusted by means of the resistor 5, which is adjustable for that purpose, but this adjustment can also be effected by making one of the base resistors 12 and 13 adjustable or by replacing these base resistors by an adjustable potentiometer.
  • pup-transistors have been shown in the circuit diagram, npn-transistors can be used too, provided that the polarity of the supply voltage is reversed.
  • Switching circuit for an electrically heated blanket comprising one or more resistors with negative temperature coeflicient which are arranged in the blanket and which serve as temperature sensors and control the switching circuit, wherein the heating element is connected to the supply source through a normally open contact of a relay, the coil of which is connected in the collector circuit of a control transistor, the base electrode of which is through a conventional resistor connected to the collector supply line and through the resistor(s) with negative temperature coefficient is connected to the emitter supply line whilst the control circuit is provided with a guard transistor, the base electrode of Which is connected to the base electrode of the control transistor, whilst its emitter electrode is connected to the collector electrode of the control transistor and its collector electrode is connected to the collector supply line.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Control Of Resistance Heating (AREA)
  • Control Of Temperature (AREA)
US449463A 1964-05-06 1965-04-20 Switching circuit for an electrically heated blanket Expired - Lifetime US3360693A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6405085A NL6405085A (xx) 1964-05-06 1964-05-06

Publications (1)

Publication Number Publication Date
US3360693A true US3360693A (en) 1967-12-26

Family

ID=19790034

Family Applications (1)

Application Number Title Priority Date Filing Date
US449463A Expired - Lifetime US3360693A (en) 1964-05-06 1965-04-20 Switching circuit for an electrically heated blanket

Country Status (4)

Country Link
US (1) US3360693A (xx)
DE (1) DE1263946B (xx)
GB (1) GB1038759A (xx)
NL (2) NL6405085A (xx)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3446942A (en) * 1967-01-10 1969-05-27 Us Navy Window de-icing controller circuit
US3480839A (en) * 1966-07-01 1969-11-25 Gylling & Co Ab Device for discoupling relays
US3526968A (en) * 1968-01-12 1970-09-08 Fedders Corp Electronic control circuit for clothes dryers
US3564203A (en) * 1968-06-05 1971-02-16 Hitachi Heating Appl Automatic temperature control device for electric blanket
US3947656A (en) * 1974-08-26 1976-03-30 Fast Heat Element Manufacturing Co., Inc. Temperature controlled cartridge heater
US4320285A (en) * 1979-05-10 1982-03-16 Koether Bernard G Primary thermostat using cooking computer temperature probe with control transfer upon probe failure
US4506137A (en) * 1983-02-18 1985-03-19 Meister Jack B Temperature responsive control circuit for electric window de-fogger/deicer heater
US4814583A (en) * 1986-05-02 1989-03-21 Safeway (Australasia) Limited Temperature controller for a waterbed

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2262691C3 (de) * 1972-12-21 1982-02-11 Vdo Adolf Schindling Ag, 6000 Frankfurt Elektronischer Temperaturschalter

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3105175A (en) * 1959-05-26 1963-09-24 Siliani Pier Luigi Self-adjusting condition responsive relay circuit
US3131314A (en) * 1961-01-03 1964-04-28 Minnesota Mining & Mfg Temperature control trigger employing emitter resistor having value of transistor's base-to-emitter resistance
US3241001A (en) * 1962-09-04 1966-03-15 Bendix Corp Condition responsive control network
US3270184A (en) * 1963-01-09 1966-08-30 Negromanti Antonio Temperature sensitive control wires provided with transistors for electrically heated pads, blankets and the like

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3105175A (en) * 1959-05-26 1963-09-24 Siliani Pier Luigi Self-adjusting condition responsive relay circuit
US3131314A (en) * 1961-01-03 1964-04-28 Minnesota Mining & Mfg Temperature control trigger employing emitter resistor having value of transistor's base-to-emitter resistance
US3241001A (en) * 1962-09-04 1966-03-15 Bendix Corp Condition responsive control network
US3270184A (en) * 1963-01-09 1966-08-30 Negromanti Antonio Temperature sensitive control wires provided with transistors for electrically heated pads, blankets and the like

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3480839A (en) * 1966-07-01 1969-11-25 Gylling & Co Ab Device for discoupling relays
US3446942A (en) * 1967-01-10 1969-05-27 Us Navy Window de-icing controller circuit
US3526968A (en) * 1968-01-12 1970-09-08 Fedders Corp Electronic control circuit for clothes dryers
US3564203A (en) * 1968-06-05 1971-02-16 Hitachi Heating Appl Automatic temperature control device for electric blanket
US3947656A (en) * 1974-08-26 1976-03-30 Fast Heat Element Manufacturing Co., Inc. Temperature controlled cartridge heater
US4320285A (en) * 1979-05-10 1982-03-16 Koether Bernard G Primary thermostat using cooking computer temperature probe with control transfer upon probe failure
US4506137A (en) * 1983-02-18 1985-03-19 Meister Jack B Temperature responsive control circuit for electric window de-fogger/deicer heater
US4814583A (en) * 1986-05-02 1989-03-21 Safeway (Australasia) Limited Temperature controller for a waterbed

Also Published As

Publication number Publication date
NL6405085A (xx) 1965-11-08
NL122023C (xx) 1900-01-01
GB1038759A (en) 1966-08-10
DE1263946B (de) 1968-03-21

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