US3673381A - Thermostatless blanket control circuit - Google Patents

Thermostatless blanket control circuit Download PDF

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Publication number
US3673381A
US3673381A US192181A US3673381DA US3673381A US 3673381 A US3673381 A US 3673381A US 192181 A US192181 A US 192181A US 3673381D A US3673381D A US 3673381DA US 3673381 A US3673381 A US 3673381A
Authority
US
United States
Prior art keywords
diode
radiation
blanket
resistor
protection circuit
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
US192181A
Other languages
English (en)
Inventor
George C Crowley
Gordon S Carlson
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.)
Nortel Networks Ltd
Original Assignee
Northern Electric Co Ltd
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 Northern Electric Co Ltd filed Critical Northern Electric Co Ltd
Application granted granted Critical
Publication of US3673381A publication Critical patent/US3673381A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • H05B3/34—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater flexible, e.g. heating nets or webs
    • H05B3/342—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater flexible, e.g. heating nets or webs heaters used in textiles
    • 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
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
    • H02H5/04—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature
    • H02H5/042—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature using temperature dependent resistors
    • H02H5/043—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature using temperature dependent resistors the temperature dependent resistor being disposed parallel to a heating wire, e.g. in a heating blanket
    • 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
    • H05B2203/00—Aspects relating to Ohmic resistive heating covered by group H05B3/00
    • H05B2203/014—Heaters using resistive wires or cables not provided for in H05B3/54

Definitions

  • ABSTRACT An overload protection circuit for an electric heating blanket is provided.
  • a sensing element in the blanket is coupled to a neon-filled diode.
  • the diode ceases to emit light and a bimetallic element in series with a light-responsive resistor causes a pair of contacts in series with the heating element to open.
  • Electric heating blankets are commonly constructed with a heat-sensitive sensing wire or element and a heating .wire or element.
  • One frequently encountered electric heating blanket construction consists of a flexible insulating core around which the heating wire and sensing wire are wound. The heating and sensing wire are separated by a layer of heat sensitive material. The resistance of the heat-sensitive material varies inversly with the temperature of the heating wire and this variation is sensed by the sensing wire to provide for overload protection.
  • An insulating covering is preferably supplied over the sensing wire.
  • Control for a blanket of the type described is conventionally achieved by a means of a thermally sensitive switch which has a pair of contacts coupled in series with the heating wire.
  • the sensing wire may be coupled to the control circuit of a second thermally sensitive switch which has pair of overload contacts in series with the heating wire.
  • the second thermal switch provides overload protection for the blanket.
  • the bimetallic thermal control switches which are commonly used to control the operation of the overload contacts are expensive and are capable of handling only a very small amount of power. Moreover, these switches tend to be overly sensitive and are difficult to manufacture.
  • FIGURE is a schematic diagram of an embodiment of the present invention.
  • the electric blanket 10 which incorporates the present invention is indicated by the reference number of the FIGURE.
  • the electric blanket 10 is constructed in a somewhat conventional manner in that it has a heating wire 12 and a sensing wire 14 incorporated therein.
  • the length of the sensing wire is approximately equal to one-half the length of the heating wire 12, which is shown schematically in the figure by the two half length sections 12a and 12b.
  • the sensing wire 14 is wound through only one half of the electric blanket 10, but unlike most sensing wires the sensing wire 14 is able to carry enough electrical current to function as a heating wire also.
  • the sensing wire 14 may be physically located in a portion of the heating blanket with either of the half-length segments of the heating wire in proximity to it.
  • the resistance of the heating section which is in proximity to the sensing wire 14 will be however slightly different from the resistance of the other section of heating wire in order to provide for temperature equalization across the entire heating blanket I0.
  • the heating wire 12 is connected in series with the thermal control element 16 of the thermal switch 18 across the input voltage line.
  • the element 16 is a conventional bimetal thermal control element that is responsive to the current that flows through the heating wire 12 and it is adjustable by the user by means of a conventional adjustment screw 180.
  • the switch 18 causes the connection between the points 18a and 18b to be repeatedly made and broken in a cyclic manner. The length of time that the connection is made during a given time period is determined by the setting of the adjustment screw.
  • an overload switch 20 must be provided to insure that an overload condition does not damage the blanket and possibly result in a dangerous condition for the user of the blanket.
  • the overload switch 20 closes the heating wire circuit through the points 20a and 20b since the On-Ofi" switch 28 is in its On position and electrical connection is also made between the points 280 and 28b.
  • the bimetallic thermal control element 22 that controls the making and breaking of the switch 20 is coupled to the neon-filled diode 24.
  • the diode 24 is coupled to the sensing wire 14 which in turn is coupled to the current limiting resistor 30.
  • the diode 24 is normally energized so that the neon gas in the diode 24 is ionized and the diode 24 is consequently emitting light.
  • the sensing wire 14 is made of a material which has a decreased resistance when its temperature increases. When an overload condition occurs the sensing wire 14 heats up and the resistance of the sensing wire then reduces sufficiently to cause the ionized gas in the diode 24 to be extinguished. When this occurs light will no longer be emitted by the diode 24.
  • the light emission state of the diode 24 is used in the manner described below to control a light-responsive switch which opens and closes the heating wire circuit and it also may be used to give the user a visual indication of the overload condition if desired.
  • the current through bimetallic control element 22 controls contacts of the switch 20 which makes and breaks the electrical connection between the points 20a and 20b.
  • the light-responsive resistor 26 which may be a cadmium sulphide cell or other suitable element.
  • the resistance of the light responsive resistor 26 is such that the current through the bimetallic element 22 causes sufficient heating of the element 22 so that itdeflects enough to keep the switch 20 closed thereby completing the circuit between the points 20a and 20b when the neon gas in the diode 24 is ionized.
  • the On-Off switch 28 has a contact 28c which momentarily contacts the moving contact of the switch 28 when the switch is being turned on. This momentarily places the full line voltage across the resistor 26, and if the resistance of the resistor 26 is below a predetermined minimum value, it will be burned out causing an open circuit thereby making the overload circuit inoperative to close switch 20. This arrangement thus prevents ener- .gization of the heating elements 12 in the event that the overload circuit is not in condition to operate.
  • said radiation responsive means is a resistor which has a resistance that varies as a function of the radiation said resistor receives from said diode.
  • An overload protection circuit as set forth in claim 2 further comprising a blanket energizing switch means which has contacts that momentarily place line voltage across said resistor when said switch is being changed from its off and its on position.
  • control means is a bimetallic control element that is coupled in series with said radiation responsive means across said series combination of said diode and said sensing means.
  • An overload protection circuit as set forth in claim 4 wherein said radiation responsive means is a resistor which has a resistance that varies as a function of the radiation said resistor receives from said diode.
  • An overload protection circuit as set forth in claim 5 further comprising a blanket energizing switch means which has contacts that momentarily place line voltage across said resistor when said switch is being changed from its off to its on position.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Textile Engineering (AREA)
  • Control Of Resistance Heating (AREA)
US192181A 1971-10-26 1971-10-26 Thermostatless blanket control circuit Expired - Lifetime US3673381A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US19218171A 1971-10-26 1971-10-26

Publications (1)

Publication Number Publication Date
US3673381A true US3673381A (en) 1972-06-27

Family

ID=22708595

Family Applications (1)

Application Number Title Priority Date Filing Date
US192181A Expired - Lifetime US3673381A (en) 1971-10-26 1971-10-26 Thermostatless blanket control circuit

Country Status (5)

Country Link
US (1) US3673381A (enrdf_load_html_response)
JP (1) JPS4850241A (enrdf_load_html_response)
AU (1) AU4531672A (enrdf_load_html_response)
CA (1) CA932009A (enrdf_load_html_response)
GB (1) GB1403044A (enrdf_load_html_response)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4034185A (en) * 1975-09-02 1977-07-05 Northern Electric Company Electric blanket control circuit
FR2406330A1 (fr) * 1977-10-11 1979-05-11 Dreamland Electrical Appliance Circuit de chauffage, notamment pour couvertures et coussins electriques
DE3008221A1 (de) * 1979-03-05 1980-09-18 Sunbeam Corp Schutzvorrichtung fuer eine elektrische heizdecke
US10136735B2 (en) 2014-11-19 2018-11-27 Polygroup Macau Limited (Bvi) Systems and methods for air mattress temperature control

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4436986A (en) * 1981-11-23 1984-03-13 Sunbeam Corporation Electric blanket safety circuit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3356825A (en) * 1966-07-18 1967-12-05 Fieldcrest Mills Inc Electrically heated bedcover and protective circuit
US3361941A (en) * 1964-05-06 1968-01-02 Indoheem N V Switching circuit for an electrically heated blanket
US3445631A (en) * 1966-03-14 1969-05-20 Indoheem Nv Safety system for an electrically heated blanket

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS447389Y1 (enrdf_load_html_response) * 1965-08-30 1969-03-20

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3361941A (en) * 1964-05-06 1968-01-02 Indoheem N V Switching circuit for an electrically heated blanket
US3445631A (en) * 1966-03-14 1969-05-20 Indoheem Nv Safety system for an electrically heated blanket
US3356825A (en) * 1966-07-18 1967-12-05 Fieldcrest Mills Inc Electrically heated bedcover and protective circuit

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4034185A (en) * 1975-09-02 1977-07-05 Northern Electric Company Electric blanket control circuit
FR2406330A1 (fr) * 1977-10-11 1979-05-11 Dreamland Electrical Appliance Circuit de chauffage, notamment pour couvertures et coussins electriques
DE3008221A1 (de) * 1979-03-05 1980-09-18 Sunbeam Corp Schutzvorrichtung fuer eine elektrische heizdecke
US10136735B2 (en) 2014-11-19 2018-11-27 Polygroup Macau Limited (Bvi) Systems and methods for air mattress temperature control

Also Published As

Publication number Publication date
AU4531672A (en) 1974-02-07
CA932009A (en) 1973-08-14
GB1403044A (en) 1975-08-13
JPS4850241A (enrdf_load_html_response) 1973-07-16

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