US3858027A - Road vehicle rear window heater circuits - Google Patents

Road vehicle rear window heater circuits Download PDF

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Publication number
US3858027A
US3858027A US00338221A US33822173A US3858027A US 3858027 A US3858027 A US 3858027A US 00338221 A US00338221 A US 00338221A US 33822173 A US33822173 A US 33822173A US 3858027 A US3858027 A US 3858027A
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Prior art keywords
transistor
rear window
switch
heating means
battery
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Expired - Lifetime
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US00338221A
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E Phillips
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Lucas Electrical Co Ltd
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Lucas Electrical Co Ltd
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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
    • H05B3/84—Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields
    • 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
    • H05B1/0227—Applications
    • H05B1/023—Industrial applications
    • H05B1/0236—Industrial applications for vehicles
    • 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
    • H05B2203/035—Electrical circuits used in resistive heating apparatus

Definitions

  • a circuit according to the invention includes a manually operable switch which is resiliently urged to an open position, a capacitor which is charged upon momentary closure of the switch, and a bistable trigger circuit which when the capacitor is charged is driven from a first state to a second state in which it causes the heater to be energised, the trigger circuit returning to said first state and de-energising the'heater when the capacitor has discharged to a predetermined level.
  • a trigger circuit has the advantage that the periods of which the heater is energised can be accurately determined, because the trigger circuit reverts to its first state quickly when the capacitor has discharged to the appropriate level.
  • the trigger circuit is a Schmitt trigger circuit.
  • the accompanying drawing is a circuit diagram illustrating one example of the invention.
  • the battery 11 of a road vehicle has its negative terminal connected to a supply line 12 which is earthed, and its positive terminal connected through the vehicle ignition switch 13 and a diode 14 in series to a supply line 15.
  • the junction of the ignition switch 13 and diode 14 is connected through a manually operable switch 16 and a capacitor 17 in series to the line 12, and the junction of the switch 16 and capacitor 17 is connected through a resistor 18 which may be variable or pre-set to the base of an n-p-n transistor 19.
  • the transistor 19 has its collector connected to the line 15 through a resistor 21, and the collector is further connected through a resistor 22 to the base of an n-p-n transistor 23 which has its base connected through a resistor 24 to the line 12, and its collector connected through a resistor 25 to the line 15.
  • the emitters of the transistors 19 and 23 are connected through a resistor 26 to the line 12.
  • the collector of the transistor 23 is connected through a resistor 27 to the base of an n-p-n transistor 28 having its emitter connected to the line 12 and its collector connected to the line 15 through the winding 29 of a relay, the winding 29 being bridged by a diode 31 and serving when energised to close a normally open contact 32 which is connected to the positive battery terminal through the ignition switch 13, and to the line 12 through the rear window heater 33 of the rear window 35 of the vehicle.
  • the heater 33 is bridged by a warning lamp 34 which conveniently is combined with the switch 16.
  • the switch 16 is resiliently urged to an open position, but on closing the switch momentarily, the capacitor 17 charges instantaneously to the supply voltage and the Schmitt trigger circuit constituted by the transistors 19 and 23 and their associated components assumes a state in which the transistor 19 is on and the transistor 23 is off.
  • Current flows through the resistors 25 and 27 to turn on the transistor 28, energising the winding 29 to close the contact 32 and energise the heater 33.
  • the lamp 34 is illuminated to indicate to the driver that the heater 33 is in operation.
  • the capacitor 17 discharges through the resistor 18, the base-emitter of the transistor 19 and the resistor 26, and the resistor 18 is adjusted or pre-set to provide a substantial delay, for example five minutes.
  • the Schmitt trigger circuit switches rapidly to its alternative state in which the transistor 19 is off and the transistor 23 is on.
  • current flowing through the resistor 25 is diverted by way of the transistor 23, the resistor 26 having a load value relative to the resistor 25, so that there is a substantial voltage swing at the collector of the transistor 23.
  • Conduction of the transistor 23 causes the transistor 28 to turn off, de-energising the winding 29 so that the heater 33 is switched off and the lamp 34 is extinguished.
  • the purpose of the diode 14 is to protect the transistors from damage resulting from reverse polarity transients caused by inductive ignition loads.
  • a road vehicle rear window heater circuit which comprises:
  • a battery connected to said rear window heating means for supplying electrical energy thereto;
  • timing circuit means connected between said battery and said rear window heating means for selectively actuating said rear window heating means for a predetermined time interval after the closure of said first switch, said timing circuit means comprising:
  • bistable trigger circuit comprising first and second transistors connected in a Schmitt trigger configuration, the base of said first transistor connected to receive the charge from said capacitor to initially be rendered conductive while said second transistor is rendered non-conductive;
  • a relay having a coil, and a pair of contacts connected between said first switch and said heating means, said coil and contacts being actuated by the output from said third transistor for energizing said rear window heating means;
  • said first transistor being rendered non-conductive after the discharge of said capacitor to thereby render said second transistor conductive and said third transistor non-conductive to thereby deactivate said relay and disconnect said rear window heating means from said battery.

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  • Control Of Resistance Heating (AREA)
  • Control Of Electric Motors In General (AREA)
  • Nozzles (AREA)

Abstract

A road vehicle rear window heater circuit is operated by a manually operable switch urged to an open position. Closure of the switch charges a capacitor, which controls a bi-stable trigger circuit determining the length of time for which the heater remains on.

Description

United States Patent 1191 1111 3,858,027
Phillips Dec. 31, 1974 [54] RoAD VEHICLE REAR WINDOW HEATER 2,725,605 12/1955 Haltenberger 219/203 CIRCUITS 3,287,608 6/1963 Pokrant 307/293 x 3,409,759 11/1968 Boicey et al. 219/203 x Inventor: Edward G a il ips, C ne, 3,515,853 6/1970 McAdams 219/501 x England 3,721,832 3/1973 Lee 307/293 x 3,745,382 7/1973 Hoge et a1. 307/293 [73] Assignee: The Lucas Electrical Company Limited, Birmingham, England 22 Filed; Man 5 97 Primary Examiner-J. V. Truhe Assistant Examiner-Clifford C. Shaw [21] Appl' 33-87221 Attorney, Agent,'0r FirmHolman & Stern [30] Foreign Application Priority Data Apr. 7, 1972 Great Britain 16055/72 7 ABSTRACT [52] Cl 219/203 2 219/501 A road vehicle rear window heater circuit is operated Int Cl by a manually operable switch urged to an open posi- Field of Search 219mm), um. Closure of the swltch charges a capac1tor, wh1ch controls a bi-stable trigger circuit determining the 219/492 522; 307/293 length of time for which the heater remains on.
[56] 7 References Cited 1 Cl 1 D F.
UNITED STATES PATENTS rawmg 1,686,146 1/1927 Cummings 2l9/203 X 25 \Zg l 32 ROAD VEHICLE REAR WINDOW HEATER CIRCUITS This invention relates to road vehicle rear window heater circuits.
A circuit according to the invention includes a manually operable switch which is resiliently urged to an open position, a capacitor which is charged upon momentary closure of the switch, and a bistable trigger circuit which when the capacitor is charged is driven from a first state to a second state in which it causes the heater to be energised, the trigger circuit returning to said first state and de-energising the'heater when the capacitor has discharged to a predetermined level.
The use of a trigger circuit has the advantage that the periods of which the heater is energised can be accurately determined, because the trigger circuit reverts to its first state quickly when the capacitor has discharged to the appropriate level. Preferably, the trigger circuit is a Schmitt trigger circuit.
The accompanying drawing is a circuit diagram illustrating one example of the invention.
Referring to the drawing, the battery 11 of a road vehicle has its negative terminal connected to a supply line 12 which is earthed, and its positive terminal connected through the vehicle ignition switch 13 and a diode 14 in series to a supply line 15. The junction of the ignition switch 13 and diode 14 is connected through a manually operable switch 16 and a capacitor 17 in series to the line 12, and the junction of the switch 16 and capacitor 17 is connected through a resistor 18 which may be variable or pre-set to the base of an n-p-n transistor 19.
The transistor 19 has its collector connected to the line 15 through a resistor 21, and the collector is further connected through a resistor 22 to the base of an n-p-n transistor 23 which has its base connected through a resistor 24 to the line 12, and its collector connected through a resistor 25 to the line 15. The emitters of the transistors 19 and 23 are connected through a resistor 26 to the line 12.
The collector of the transistor 23 is connected through a resistor 27 to the base of an n-p-n transistor 28 having its emitter connected to the line 12 and its collector connected to the line 15 through the winding 29 of a relay, the winding 29 being bridged by a diode 31 and serving when energised to close a normally open contact 32 which is connected to the positive battery terminal through the ignition switch 13, and to the line 12 through the rear window heater 33 of the rear window 35 of the vehicle. The heater 33 is bridged by a warning lamp 34 which conveniently is combined with the switch 16.
The switch 16 is resiliently urged to an open position, but on closing the switch momentarily, the capacitor 17 charges instantaneously to the supply voltage and the Schmitt trigger circuit constituted by the transistors 19 and 23 and their associated components assumes a state in which the transistor 19 is on and the transistor 23 is off. Current flows through the resistors 25 and 27 to turn on the transistor 28, energising the winding 29 to close the contact 32 and energise the heater 33. The lamp 34 is illuminated to indicate to the driver that the heater 33 is in operation.
The capacitor 17 discharges through the resistor 18, the base-emitter of the transistor 19 and the resistor 26, and the resistor 18 is adjusted or pre-set to provide a substantial delay, for example five minutes. However, when the capacitor has discharged to a predetermined level, the Schmitt trigger circuit switches rapidly to its alternative state in which the transistor 19 is off and the transistor 23 is on. As soon as this happens, current flowing through the resistor 25 is diverted by way of the transistor 23, the resistor 26 having a load value relative to the resistor 25, so that there is a substantial voltage swing at the collector of the transistor 23. Conduction of the transistor 23 causes the transistor 28 to turn off, de-energising the winding 29 so that the heater 33 is switched off and the lamp 34 is extinguished.
The purpose of the diode 14 is to protect the transistors from damage resulting from reverse polarity transients caused by inductive ignition loads.
I claim:
1. A road vehicle rear window heater circuit, which comprises:
a rear window of a road vehicle having rear window heating means associated therewith;
a battery connected to said rear window heating means for supplying electrical energy thereto;
a first switch connected in series between said battery and said rear window heating means; and
timing circuit means connected between said battery and said rear window heating means for selectively actuating said rear window heating means for a predetermined time interval after the closure of said first switch, said timing circuit means comprising:
a second switch which is resiliently urged to an open position;
a capacitor connected to said battery through said second switch and said first switch, said capacitor being charged upon momentary closure of said second switch;
a bistable trigger circuit comprising first and second transistors connected in a Schmitt trigger configuration, the base of said first transistor connected to receive the charge from said capacitor to initially be rendered conductive while said second transistor is rendered non-conductive;
a third transistor connected across said second transistor, said third transistor being initially driven into conduction by a connection through said first switch to said battery;
a relay having a coil, and a pair of contacts connected between said first switch and said heating means, said coil and contacts being actuated by the output from said third transistor for energizing said rear window heating means;
said first transistor being rendered non-conductive after the discharge of said capacitor to thereby render said second transistor conductive and said third transistor non-conductive to thereby deactivate said relay and disconnect said rear window heating means from said battery.

Claims (1)

1. A road vehicle rear window heater circuit, which comprises: a rear window of a road vehicle having rear window heating means associated therewith; a battery connected to said rear window heating means for supplying electrical energy thereto; a first switch connected in series between said battery and said rear window heating means; and timing circuit means connected between said battery and said rear window heating means for selectively actuating said rear window heating means for a predetermined time interval after the closure of said first switch, said timing circuit means comprising: a second switch which is resiliently urged to an open position; a capacitor connected to said battery through said second switch and said first switch, said capacitor being charged upon momentary closure of said second switch; a bistable trigger circuit comprising first and second transistors connected in a Schmitt trigger configuration, the base of said first transistor connected to receive the charge from said capacitor to initially be rendered conductive while said second transistor is rendered non-conductive; a third transistor connected across said second transistor, said third transistor being initially driven into conduction by a connection through said first switch to said battery; a relay having a coil, and a pair of contacts connected between said first switch and said heating means, said coil and contacts being actuated by the output from said third transistor for energizing said rear window heating means; said first transistor being rendered non-conductive after the discharge of said capacitor to thereby render said second transistor conductive and said third transistor non-conductive to thereby deactivate said relay and disconnect said rear window heating means from said battery.
US00338221A 1972-04-07 1973-03-05 Road vehicle rear window heater circuits Expired - Lifetime US3858027A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1605572A GB1426176A (en) 1972-04-07 1972-04-07 Road vehicle rear window heater circuits

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US3858027A true US3858027A (en) 1974-12-31

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US (1) US3858027A (en)
JP (1) JPS4915137A (en)
DE (1) DE2317488A1 (en)
FR (1) FR2179425A5 (en)
GB (1) GB1426176A (en)
IT (1) IT982960B (en)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937922A (en) * 1974-08-27 1976-02-10 General Electric Company Control system
US3944893A (en) * 1973-10-29 1976-03-16 Trw Inc. Vehicle window heater control device
US3973140A (en) * 1974-01-29 1976-08-03 The Lucas Electrical Company Limited Control circuits for vehicle rear window heaters
US4084126A (en) * 1976-02-11 1978-04-11 Ford Motor Company Controlled and energization circuit for electrically heated vehicle windows
US4225777A (en) * 1978-08-18 1980-09-30 Mark Schindler Multiple variable phase control circuit
US4276483A (en) * 1978-04-21 1981-06-30 Trw Inc. Timed electric switch
US4510376A (en) * 1982-07-22 1985-04-09 Alco Foodservice Equipment Company Variable timing system for toasters and similar appliances
US4520258A (en) * 1982-04-28 1985-05-28 Bayerische Motoren Werke A.G. System concomitantly controlling passenger compartment and electric auxiliary heating in automatic vehicles
US4539466A (en) * 1983-01-28 1985-09-03 Nissan Motor Co., Ltd. Electric heating apparatus for dissipating fog from a window
US4555743A (en) * 1982-07-27 1985-11-26 Kabushiki Kaisha Tokai Rika Denki Seisakusho Timer circuit
US4673797A (en) * 1985-10-28 1987-06-16 Donnelly Corporation Power control for heated windshields
US4730097A (en) * 1986-08-15 1988-03-08 General Motors Corporation Dual mode windshield heater control
US4829163A (en) * 1988-02-08 1989-05-09 General Motors Corporation Crack detector for heated glass panel
US5072098A (en) * 1990-06-11 1991-12-10 Chrysler Corporation Electrically heated windshield controller
US5852284A (en) * 1997-01-07 1998-12-22 Libbey-Owens-Ford Co. Insulating glass with capacitively coupled heating system
US20100032422A1 (en) * 2008-08-08 2010-02-11 Hong Fu Jin Precision Industry (Shenzhen)Co., Ltd. Data input device
US20190069347A1 (en) * 2017-08-31 2019-02-28 Taiwan Semiconductor Manufacturing Company, Ltd. Photonic heater

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4118582A (en) * 1975-10-28 1978-10-03 E. I. Du Pont De Nemours And Company Purification of spent ethylene glycol
FR2421589A1 (en) * 1977-06-17 1979-11-02 Saint Gobain Vehicle rear window heating circuit - consists of humidity detector and time switch for circuit with thermistor
US4506137A (en) * 1983-02-18 1985-03-19 Meister Jack B Temperature responsive control circuit for electric window de-fogger/deicer heater

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1686146A (en) * 1927-01-31 1928-10-02 Everett H Price Heater for windshields
US2725605A (en) * 1950-04-24 1955-12-06 Haltenberger Jules Automobile glass defrosting and drying
US3287608A (en) * 1963-06-03 1966-11-22 Westinghouse Air Brake Co Time delay control circuit
US3409759A (en) * 1966-07-21 1968-11-05 Libbey Owens Ford Glass Co Laminated transparent panel incorporating electrical heating wires and method of producing same
US3515853A (en) * 1967-09-15 1970-06-02 North American Rockwell Heating apparatus
US3721832A (en) * 1972-03-29 1973-03-20 Gen Electric Time delay after de-energization circuit
US3745382A (en) * 1972-02-18 1973-07-10 Rhomega Syst Inc Solid state timer circuit for controlling the energization time of a load

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1686146A (en) * 1927-01-31 1928-10-02 Everett H Price Heater for windshields
US2725605A (en) * 1950-04-24 1955-12-06 Haltenberger Jules Automobile glass defrosting and drying
US3287608A (en) * 1963-06-03 1966-11-22 Westinghouse Air Brake Co Time delay control circuit
US3409759A (en) * 1966-07-21 1968-11-05 Libbey Owens Ford Glass Co Laminated transparent panel incorporating electrical heating wires and method of producing same
US3515853A (en) * 1967-09-15 1970-06-02 North American Rockwell Heating apparatus
US3745382A (en) * 1972-02-18 1973-07-10 Rhomega Syst Inc Solid state timer circuit for controlling the energization time of a load
US3721832A (en) * 1972-03-29 1973-03-20 Gen Electric Time delay after de-energization circuit

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3944893A (en) * 1973-10-29 1976-03-16 Trw Inc. Vehicle window heater control device
US3973140A (en) * 1974-01-29 1976-08-03 The Lucas Electrical Company Limited Control circuits for vehicle rear window heaters
US3937922A (en) * 1974-08-27 1976-02-10 General Electric Company Control system
US4084126A (en) * 1976-02-11 1978-04-11 Ford Motor Company Controlled and energization circuit for electrically heated vehicle windows
US4276483A (en) * 1978-04-21 1981-06-30 Trw Inc. Timed electric switch
US4370565A (en) * 1978-04-21 1983-01-25 Trw Inc. Timed electric switch
US4225777A (en) * 1978-08-18 1980-09-30 Mark Schindler Multiple variable phase control circuit
US4520258A (en) * 1982-04-28 1985-05-28 Bayerische Motoren Werke A.G. System concomitantly controlling passenger compartment and electric auxiliary heating in automatic vehicles
US4510376A (en) * 1982-07-22 1985-04-09 Alco Foodservice Equipment Company Variable timing system for toasters and similar appliances
US4555743A (en) * 1982-07-27 1985-11-26 Kabushiki Kaisha Tokai Rika Denki Seisakusho Timer circuit
US4539466A (en) * 1983-01-28 1985-09-03 Nissan Motor Co., Ltd. Electric heating apparatus for dissipating fog from a window
US4673797A (en) * 1985-10-28 1987-06-16 Donnelly Corporation Power control for heated windshields
US4730097A (en) * 1986-08-15 1988-03-08 General Motors Corporation Dual mode windshield heater control
US4829163A (en) * 1988-02-08 1989-05-09 General Motors Corporation Crack detector for heated glass panel
US5072098A (en) * 1990-06-11 1991-12-10 Chrysler Corporation Electrically heated windshield controller
US5852284A (en) * 1997-01-07 1998-12-22 Libbey-Owens-Ford Co. Insulating glass with capacitively coupled heating system
US20100032422A1 (en) * 2008-08-08 2010-02-11 Hong Fu Jin Precision Industry (Shenzhen)Co., Ltd. Data input device
US8253072B2 (en) * 2008-08-08 2012-08-28 Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. Data input device
US20190069347A1 (en) * 2017-08-31 2019-02-28 Taiwan Semiconductor Manufacturing Company, Ltd. Photonic heater
US10638543B2 (en) * 2017-08-31 2020-04-28 Taiwan Semiconductor Manufacturing Company, Ltd. Photonic heater
US11540357B2 (en) 2017-08-31 2022-12-27 Taiwan Semiconductor Manufacturing Company, Ltd. Photonic heater

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Publication number Publication date
GB1426176A (en) 1976-02-25
FR2179425A5 (en) 1973-11-16
JPS4915137A (en) 1974-02-09
IT982960B (en) 1974-10-21
DE2317488A1 (en) 1973-10-18

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