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Publication numberUS3749886 A
Publication typeGrant
Publication dateJul 31, 1973
Filing dateDec 6, 1971
Priority dateDec 6, 1971
Publication numberUS 3749886 A, US 3749886A, US-A-3749886, US3749886 A, US3749886A
InventorsMichaelsen D
Original AssigneeDale Electronics
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electrical heating pad
US 3749886 A
An electrically conductive sheet of flexible material includes conductive particles and channel-shaped electrodes are provided on opposite ends and are connected by lead wires to a power source. A flexible insulating envelope is bonded to and protects the conductive sheet. Holes may be provided in the conductive sheet to facilitate bonding between the protective cover and the conductive sheet. The conductive particles may be carbon and the sheet may be formed from fibrous material or rubber. The protective sheet may be molded from plastic or rubber having a very low carbon content.
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Description  (OCR text may contain errors)

United States Patent [1 1 Michaelsen ELECTRICAL HEATING PAD [75] Inventor: Dwight W. Michaelsen, Columbus,


[73] Assignee: Dale Electronics, Inc., Columbus,


22 Filed: Dec. 6, 1971 2 11 Appl. No.: 204,860

521 U.S. 01...; 219/s 28', 2197541, 2'19/543,

219/549, 338/212 [51] Int. Cl. 1105b 3/36 [58] Field of Search 219/211, 212, 213,

[56] References Cited UNITED STATES PATENTS 2,458,184 1/1949 Marick 219/543 X 3,344,385 9/1967 Bartos et a1 338/212 3,535,494 10/1970 Armbruster.. 219/528 3,558,858 1/1971 Luger, Jr. 219/528 3,627,981 12/1971 Kuhn 219/549 X 3,697,728 10/1972 Stirzenbecher 219/548 2,473,183 6/1949 Watson 219/543 2,688,070

8/1954 Freedlander 219/528 [451 July 31, 1973 Glicksman 219/528 X 3,281,579 10/1966- 3,367,851 2/1968 Filreis et al. 204/2 3,283,284 11/1966 Eisler 338/212 2,938,992 5/1960 Crump 219/528 3,385,959 5/1968 Ames et 219/549 2,559,077 7/1951 Johnson et a1..... 219/543 2,952,761 9/1960 Smith-Johannsen.. 219/541 3,359,524 12/1967 Gallacher et a1. 219/528 X Primary Examiner-,-Volodymyr Y. Mayewsky Attorney- Zar1ey, McKeejtitThomte 1 I [5 7 ABSTRACT An electrically conductive sheet of flexible material includesconductive particles and channel-shaped electrodes are provided on opposite ends and are connected by lead wires to a power source. A flexible'insulating envelope is bonded to and protects the conductive sheet. Holes may be provided in the conductive sheet to facilitate bonding between the protective cover and the conductive sheet. The conductive particles may be carbon and the sheet may be formed from fibrous material or rubbeLThe protective sheet may be moldedfrom plastic or rubber having a very low carbon content.

1 Claim, 2 Drawing Figures ELECTRICAL HEATING PAD Portable heaters are commonly used in and out of doors. Inside they may be used for a desk top warmer, desk foot warmer, foot stool warmer or for heating pads. Winter conditions outside make them desirale for windshield deicers, seat warmers and cat and dog house warmers.

One of the most important uses is for maintaining a battery at the optimum temperature level to maximize the battery power available for starting engines.

The heating pad of this invention contains no wires or ribbons and will not develop hot spots and burn out: There is basically nothingto breakfandcanKbecome partially damaged and still function. Theelectrical properties remain unchanged by the unit being exposed to dampness and then redrying. Further, repeated flexing has little effect on the electrical properties. The conductive element has uniform conductivity from point to point over the element regardless of the direction of current flow. Also, very important is the fact that the heater unit can be produced more inexpensively than a conventional wire-wound heater unit.

The heater unit of this invention includes a sheet of conductive material which is highly flexible and has channel-shaped electrodes at opposite ends connected to lead lines adapted to be connected to a power source.

This invention consists in the construction, arrangements and combination of the various parts of the device, whereby the-objects contemplated-are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated inthe accompanying ally in FIG. 1 by the reference numeral 10. The heatingv pad includes a flexible electrically conductive sheet 12. Suitable materials include rubber having carbon particles impregnated therein in sufficient quantities to make the sheet electrically conductive. Temsheet produced by Armstrong Cork Company, Lancaster, Pennsylvania, is also acceptable. A channel-shaped electrode 14 is secured to the opposite ends of'the sheet 12 and bonded in place by any suitable means such as the staples l6, seen in FIG. 2. The electrodes 14 are preferably brass.

An electrical lead line 16 includes one line 18 connected to one electrode while the other line 20 is connected to the opposite electrode 14. A rivet and solder connection 22 is used for connecting the lead line wires I envelope 24 of insulating material such as rubber hav-' ing no carbon or very little carbon. A flexible plastic may also be used. The conductive sheet 12 is com-- pletely sealed within the protective envelope 24 by a molding or vulcani zing process. Openings 26 are pro-.

vided in the sheet 12 to further facilitate the bonding of the envelope material to the conductive resistance sheet 12. I

I I It is seen in FIG-2 that'the electrodesl4-are inwardly, j.

spaced from the outer adjacent edges of the envelope 24 and thus provide extra protection at the ends of the heating pad and in particularly provide flexible support for the electrical lead line 16 to minimize stress and strain at the electrodes 14.

It is seen that the use of synthetic natural rubber or plastic in the envelope 24 provides resistance and protection against the action of solvents, acids, and moisture making the heating pad very suitable for industrial applications including the warming of batteries. "It is further seen that there is essentially nothing to break in this heatingpad as there are no wires or ribbons to break. Further, the" carbon impregnated resistance sheet of the battery heater of this invention can be produced more economically than a wound-wire battery' heater.

I claim: Q 1. An electrical heating pad comprising,

an electrically conductive sheet of flexible material an envelope of electrically insulative flexible material molded onto and enclosing said sheet, said envelope having a size larger than said sheet so that said.

sheet is completely enclosed therein, t said conductive sheet having a plurality of openings formed therein which receive the flexible material said conductive sheet being stapled together. i 4

, a: k a: a: e

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2458184 *Jan 15, 1944Jan 4, 1949Us Rubber CoElectrically conducting panel
US2473183 *Jul 16, 1947Jun 14, 1949Bates Mfg CoElectrically conductive fabric
US2559077 *Jul 1, 1946Jul 3, 1951Howard W JohnsonResistance element and method of preparing same
US2688070 *Mar 14, 1950Aug 31, 1954Dayton Rubber CompanyElectrically heated mattress construction
US2938992 *Apr 18, 1958May 31, 1960Electrofilm IncHeaters using conductive woven tapes
US2952761 *Apr 2, 1957Sep 13, 1960Chemelex IncElectrically conductive laminated structure and method of making same
US3281579 *Apr 21, 1964Oct 25, 1966Multi Flex Seats IncConductive rubber heating mantle
US3283284 *Jan 12, 1962Nov 1, 1966Eisler PaulElectrical heating film
US3344385 *Jan 4, 1965Sep 26, 1967Dow CorningFlexible resistance element with flexible and stretchable terminal electrodes
US3359524 *Sep 2, 1964Dec 19, 1967Ioco LtdFlexible heating elements
US3367851 *Apr 9, 1964Feb 6, 1968Minnesota Mining & MfgNon-woven conductive paper mat
US3385959 *May 26, 1965May 28, 1968Ici LtdFlexible heating elements
US3535494 *Oct 4, 1967Oct 20, 1970Armbruster FritzElectric heating mat
US3558858 *Jun 30, 1969Jan 26, 1971Delta Control IncFlexible planar heating unit adapted for mounting on complex curved surfaces
US3627981 *Nov 5, 1969Dec 14, 1971Kabel Metallwerke GhhAreal heating element
US3697728 *Dec 4, 1969Oct 10, 1972Air Plastic Service GmbhHeating devices
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4104509 *Sep 21, 1976Aug 1, 1978U.S. Philips CorporationSelf-regulating heating element
US4240212 *Jun 21, 1979Dec 23, 1980The United States Of America As Represented By The Secretary Of The NavyThermal signature targets
US4250397 *Jun 1, 1977Feb 10, 1981International Paper CompanyHeating element and methods of manufacturing therefor
US4485297 *Aug 21, 1981Nov 27, 1984Flexwatt CorporationElectrical resistance heater
US4534886 *Jan 15, 1981Aug 13, 1985International Paper CompanyNon-woven heating element
US4542285 *Aug 31, 1984Sep 17, 1985Flexwatt CorporationElectrical heater
US4574186 *Mar 24, 1983Mar 4, 1986Totoku Electric Co., Ltd.Heating sheet
US4593181 *Feb 6, 1984Jun 3, 1986Raychem CorporationHeating element having deformed buss bars
US4665304 *May 4, 1984May 12, 1987Spencer A GeorgeAnti-condensation mirror
US5925275 *Oct 2, 1997Jul 20, 1999Alliedsignal, Inc.For deicing aircraft
DE3433702A1 *Sep 13, 1984Mar 20, 1986Buchtal GmbhWand-, decken- und/oder bodenausbildung sowie verfahren zu ihrer herstellung
EP0852514A1 *Sep 27, 1996Jul 15, 1998Robbins Scientific CorporationReciprocating bath shaker
WO1986001672A1 *Aug 29, 1985Mar 13, 1986Flexwatt CorpElectrical heater
WO1986002228A1 *Sep 26, 1985Apr 10, 1986Flexwatt CorpFlexible electric sheet heater
WO1991011891A1 *Jan 24, 1991Jul 25, 1991Hastings OtisElectrically conductive laminate for temperature control of surfaces
U.S. Classification219/528, 219/549, 219/541, 338/212, 219/543
International ClassificationA61F7/00, H05B3/14
Cooperative ClassificationA61F7/02, H05B3/146, A61F2007/0045
European ClassificationH05B3/14P, A61F7/02
Legal Events
Feb 13, 1986ASAssignment
Effective date: 19851031