US3514581A - Optically transparent electrical heating element - Google Patents

Optically transparent electrical heating element Download PDF

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Publication number
US3514581A
US3514581A US733050A US3514581DA US3514581A US 3514581 A US3514581 A US 3514581A US 733050 A US733050 A US 733050A US 3514581D A US3514581D A US 3514581DA US 3514581 A US3514581 A US 3514581A
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heating element
electrolyte
optically transparent
support material
sheet
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US733050A
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English (en)
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Martin G Rocholl
Ilse Rocholl
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Gulton Industries Inc
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Gulton Industries Inc
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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
    • H05B3/86—Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields the heating conductors being embedded in the transparent or reflecting material
    • 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
    • H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
    • H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
    • H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
    • 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
    • H05B2203/013—Heaters using resistive films or coatings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S65/00—Glass manufacturing
    • Y10S65/04—Electric heat

Definitions

  • An optically transparent heating element which comprises an electrolyte solution preferably absorbed on an optically transparent support material having electrical conductors in electrical contact relationship with electrical conductors of an optically transparent insulation sheet which is stable to the electrolyte solution, the electrolyte support material being sealed within the optically transparent insulating sheet.
  • the optically transparent heating element has a positive temperature coefiicient and is self-regulating in that it does not have to be controlled by interrupting the current, but adjusts itself automatically to limit its temperature in individual areas thereof according to the heat load in such individual areas by automatically varying its local resistivity in such areas.
  • This invention relates to an optically transparent, selfregulating heating element.
  • Heating elements known in the prior art are generally composed of metal wires, foil, carbon, carbon-containing materials, semiconductors (e.g. silicon carbide) and the like. These heating elements find diversified use in such consumer goods as cooking appliances, heating apparatus, lighters, etc. In the case of metal and semiconductor heating elements, current transfer is efiected by electron conduction. Such heating elements absorb the electromagnetic energy of light, and as a result are either opaque or intensely colored. Similarly, organic semiconductors which work on the principle of electron conduction are also intensely colored substances.
  • heating elements are not suitable for use where optical transparency is desired or necessary such as in windows of automobiles, homes, offices, etc.
  • windows are a considerable source of heat absorption during cold weather which frequently results in discomfort to the occupant of an otherwise properly heated enclosure.
  • condensation forms on any window surface of a vehicle where maximum optical transparency is essential.
  • a reduction in visibility whether due to ice, snow or condensation on a window surface is a serious driving hazard. Therefore, there is a great need for a heating element which prevents condensation on a window surface by maintaining the windowsurface at an appropriate temperature and which will maintain the inside surface of a window at the same temperature as other non-transparent portions of an enclosure so as to substantially eliminate heat absorption by the window surface.
  • Such a heating element must be optically transparent and is provided by the present invention.
  • an object of the present invention to provide an optically transparent electrical heating element in the form of a flexible or rigid sheet or other shaped article that uses the ions produced by an electrolyte solution as the electric current carrier.
  • a further object of the present invention is to provide an optically transparent heating element which comprises an inorganic and/or organic acid, base and/or salt, dissolved in an aqueous or non-aqueous solvent to furnish an electrolyte solution which is enclosed by an insulating sheet material provided with conductive means for passing an electric current through the electrolyte solution.
  • Yet another object of the present invention is to provide an optically transparent electrical heating element which comprises an electrolyte solution absorbed on an optically transparent support material and an optically transparent insulating material which encases the electrolyte-containing support material and provides an airtight seal around the support material, the support material and insulating material having electrical conductors in electrical contact relationship to provide for current flow inside the sealed portion of the optically transparent heating sheet containing the electrolyte support material.
  • An additional object of the present invention is to provide an optically transparent heating element having a positive temperature coefficient which does not require the heating element to be controlled by interrupting the current supply, as by means of a thermostat or the like, but which adjusts itself automatically to limit its temperature in individual regions thereof according to the heat load in such individual regions by automatically varying the electrical resistivity in such regions.
  • FIG. 1 is an exploded perspective view of the components of an optically transparent heating element manufactured in accordance with the present invention
  • FIG. 2 is a perspective view of an assembled optically transparent heating sheet according to the present invention.
  • FIG. 3 is a fragmentary view along lines 3-3 of FIG. 2.
  • an optically transparent electrical heating element preferably in the form of a relatively flat sheet, which consists of an aqueous or non-aqueous electrolyte solution contained within an optically transparent insulating envelope which is stable and inert toward the electrolyte and which is provided with conductive means for passage of electrical current, as will be explained with reference to the drawing.
  • sheet as used herein includes flexible or rigid foil, film, plate, etc.
  • insulating envelope includes two relatively flat, flexible or rigid sheets joined together so as to provide a sealed compartment.
  • the electrolyte solution is preferably used in conjunction with an optically transparent support material in the form of a relatively flat sheet which has the characteristic of being able to support the electrolyte without itself going into solution as by absorption, adsorption, or in any other way.
  • This support material with the electrolyte will hereinafter be referred to as the electrolyte sheet.
  • the support material is preferably a polymeric substance such as a plastic, rubber or protein material.
  • the polymeric substance is preferably cross-linked in ,accordance with procedures well known in the art.
  • FIG. 2 there is shown a heating element 10 comprising an envelope portion 11 having a pair of opposing side wall portions 12 and 13 shown in FIGS. 1 and 3, each overlying one surface of a relatively flat electrolyte sheet 14 which supports the electrolyte.
  • the side wall portion 12 is of smaller dimension than side wall portion 13, as shown in FIGS. 1 and 3 to leave protruding conductive strips 19 on side wall portion 13.
  • Side wall portion 13 is provided with electrodes 15 and 16 along two opposed edges and the electrolyte sheet is also provided with electrodes 17 and 18 along two opposed edges so that electrodes 15 and 17 will be in overlying and electrical contact relationship when the heating element is assembled.
  • Electrodes 16 and 18 will be in the same overlying and electrical contact relationship to each other in the assembled heating element as electrodes 15 and 17.
  • Electrodes .15, 16, 17 and 18 may comprise conductive silver in the form of a thin foil having an adhesive coated on one surface for securing the foil to the support material.
  • the selected adhesive must be insoluble in the electrolyte that is to be absorbed on the support material.
  • the electrode may be a powder containing an adhesive which is coated onto the support material or conductive wires secured to the support material at its opposed edges or incorporated therein along the edges in a suitable manner.
  • Other materials having a high polarization voltage such as platinum, nickel and amalgamized silver may be used to form the electrodes.
  • the heating element is assembled by placing electrolyte sheet 14 between side Wall portions 12 and 13 and then sealing the edges of these side wall portions in a conventional manner such as with a high frequency welder or other hot sealing device.
  • the envelope portion .11 is formed which encases electrolyte sheet 14.
  • Conductive section of each of conductive electrodes 15 and 16 which comprise a foil of silver adhesively secured to side wall portion 13 extends outside of the envelope portion 11 and the remaining portion of each of electrodes 15 and 16 extends within the envelope portion 11 and in overlying electrical contact relationship with conductive silver electrodes 17 and 18 which comprise a foil of silver adhesively secured on electrolyte sheet 14.
  • This arrangement permits passage of current from outside of envelope portion 11 of heating element 10 into the envelope portion through leads (not shown) which are connected to the exposed section of electrodes 15 and 16 and to an alternating current supply source (not shown).
  • Electrolytes which are suitable for use with the present invention comprise aqueous or non-aqueous solutions of (a) inorganic acids, (b) organic acids, (c) inorganic and organic bases and/or salts, as well as combination of the foregoing which dissociate into ions in the aqueous or non-aqueous solvent.
  • An aqueous electrolyte may comprise, for example, materials such as hydrochloric acid, potassium chloride, phosphoric acid, acetic acid, boric acid, formic acid, etc., or a mixture of an acid and salt such as phosphoric acid and potassium phosphate, acetic acid and sodium acetate or buffer mixtures dissolved in water.
  • the selection of a particular inorganic or organic acid is not critical except that highly oxidizing acids are not desirable nor is hydrogen fluoride suitable.
  • Non-aqueous electrolytes are obtained by dissolving a dehydrated inorganic and/or organic acid, base and/or salt in a non-aqueous solvent.
  • the selected electrolyte must be one which will form ions in the desired nonaqueous solvent.
  • non-aqueous solvents examples include propylene carbonate, dimethyl formamide, dimethyl sulfamide, acetonitrile, nitrobenzene, formamide, lactic acid, N-ethyl-morpholine, monoethanolamine, ethyl acetate, cyclohexanone, 2,4-pentadione, 2-pentanone, tetramethylene sulfones, 2-chloroethanol, ethylene dipropionate, epichlorohydrin, furfural, methylthiocyanate, propionitrile, acrylonitrile.
  • Other non-aqueous solvents may also be employed.
  • salts that may be used with non-aqueous solvents include lithium perchlorate, sodium iodide, potassium iodide, etc.
  • a suitable support material is not critical except to the extent that it is desirably optically transparent and should be compatible with the electrolyte solution. This means that the selected support material must be capable of supporting the selected aqueous or non-aqueous electrolyte solution without dissolving in that solution.
  • the support material may be one which absorbs water or swells in water. Examples of such support materials include hydrocellulose, methyl cellulose, cellulose, carboxyl methyl cellulose, gelatin, agar agar, pectins, starch, dextrins, gum arabic, aginates, hemicellulose and the like.
  • suitable support materials include cellulose, acetate, cellulose acetobuylate, cel lulose propionate, ethyl cellulose, artificial horn, phenol molding resin, polyacetates, polyamides, polycarbonate, celluloid and polyesterpolyurethane elastomers.
  • the optically transparent support material may be selected from such materials as natural rubber, polyisobutylene, polymethacrylate, polystyrene, acrylonitrile-styrene copolymers, butadiene-styrene copolymers, polyvinyl carbozol, polyvinylchloride (hard and saft containing about 40% plasticizer), ethyl cellulose, cellulose acetobutyrate, cellulose propionate, ABC resins (e.g.
  • the non-aqueous solvent for the electrolyte is an alcohol, ester, ketone, ether or haloalkane
  • the optically transparent electrolyte sheet used in the heating element of the present invention may be produced as follows: a polymeric support material in the form of a relatively fiat sheet is selected which is compatible with the electrolyte solution that is to be used and provided with opposed spaced conductive electrodes 15 and 16 as previously described prior to introduction of the electrolyte solution into the sheet.
  • the necessary spacing between the electrodes for a desired heat performance (watts/square meter) of the heating element a small strip of the selected support material is placed in the desired electrolyte solution to effect swelling. After removal from the electrolyte solution the support materials square resistance is measured. This square resistance depends on the layer thickness of the support material, its swelling capacity in the electrolyte solution, the electric conductivity of the electrolyte and the swelling time of the support material in the electrolyte. After the square resistance has been measured, the electrode spacing for the desired heat output and the available working voltage acn be readily calculated.
  • this material is placed in the electrolyte solution for a time period which may range anywhere from 10 seconds to about 4 hours, depending on the absorbing and swelling characteristics of the material as Well as the square resistance which is desired and on which the electrode spacing is based.
  • the swelling of the support material may be carried out at room temperature or at elevated temperatures. The selection of a temperature is not critical and the temperature may be adjusted in accordance with the absorption properties exhibited by the support material at different temperatures.
  • the excess electrolyte on the surface of the electrolyte sheet is removed by Wiping the sheet with a rubber Wiper or the like, leaving the electrolyte sheet damp but not wet. It is important not to dry out the electrolyte sheet because this would adversely aifect current flow in the heating element.
  • the insulating envelope in which the electrolyte sheet is encased should meet the following criteria: 1) desirably optically transparent, (2) stable toward the electrolyte in the electrolyte sheet, i.e. does not absorb the electrolyte, and (3) substantially impervious to air and to the electrolyte solvent.
  • the selection of the insulating material is governed to a large extent by the nature of the electrolyte selected for the heating element.
  • the following flexible insulating materials are suitable for use with non-oxidizing aqueous electrolyte solutions: chlorinated polyether, polyethylene, polystyrene, polyvinylcarbazol, Teflon, polytrifiuorochloroethylene, etc.
  • insulating materials that are suitable include epoxy resins, urea-resin molding compounds, artificial horn, melamine resin molding compounds, phenol resin molding compounds, polyacetate, chlorinated polyether, polyamides, Teflon, polytrifluorochloroethylene, Vulcanfiber and polyester-polyurethane elastomers.
  • suitable insulating materials include chlorinated polyethers, polyethylene of high or low density, polyisobutylene, polymethyl methacrylate, polypropylene, polystyrene, polyvinylchloride (hard and soft) Teflon and polytrifluoroethylene. Insulating materials other than those exemplified above may also be employed, depending on the nature of the electrolyte material. For example, some polymeric materials are not stable in acid solutions but are stable toward basic solutions.
  • the electrolyte comprises a base solution material such as a styrene-acrylonitrile copolymer, a styrene-butadiene copolymer, ABS resins, polyvinyl carbazol, etc. may be employed because they are stable toward bases but not acids.
  • the thickness of the insulating sheet is preferably in the range from about 0.1 mm. to about 1.0 mm.
  • EXAMPLE 1 An electrolyte solution was prepared by dissolving 2 moles of potassium chloride in one mole hydrochloric acid.
  • a test strip of hydrocellulose (cellulose of the formula (C6H10'O5)200 450 treated With to obtain a Smooth and gleaming surface) having a length of cm., a width of 4 cm., and a thickness of 0.03 mm. was provided with conductive silver foil along two of its edges, the spacing being -8 cm.
  • This test strip was placed in the electrolyte solution at 20 C. for two minutes which resulted in swelling of the test strip due to absorption of the electrolyte.
  • the test strip was removed from the electrolyte solution, and its dimensions again measured. The thickness had increased to 0.062 mm. and the length and width increased about 10%.
  • the square resistance of this test strip was 1030 ohms.
  • a sheet of dry hydrocellulose foil having a thickness of .03 mm. was provided with conductive silver electrodes in the form of a thin foil having a width of 5 mm. along two edges and placed in the electrolyte solution at 20 C. for two minutes.
  • the geometric dimensions of the resulting swelled foil are 26 cm. x 15 cm. x .062 mm.
  • the conductive silver electrode spacing along the edges of the swelled foil was 25 cm.
  • This swollen optically transparent support material is placed between two sheets of optically transparent polyethylene having a thickness of about .01 mm. which has been provided with conductive silver foil electrodes along two of its edges as illustrated in the drawing.
  • the electrodes are spaced 25 cm. apart and the width of each electrode is 2 cm.
  • the two sheets are hermetically sealed by heat along the edges as illustrated in the drawing.
  • This optically transparent heating element was found to have a square resistance of 1100 ohms and an operating temperature of about 48 C. at room temperature.
  • EXAMPLE 2 An optically transparent heating element was manufactured according to Example 1, with the presence of 10% by weight of glycerine in the electrolyte solution.
  • the quantity of glycerine is not critical but is preferably in the range of 5 to about 20% by weight.
  • EXAMPLE 3 An optically transparent heating element was prepared in accordance with Example 1, using hydrocellulose foil and an electrolyte which is an aqueous solution of boric acid.
  • the optically transparent heating element of the present invention preferably has a positive temperature coeflicien-t.
  • the current absorption of any individual area of he heating element is preferably made self-regulating. This means that those areas or zones of the heating element will use less current where there is an increase in resistance due to an increase in temperature in the zone and hence selfregulate its temperature, whereas relatively colder areas of the heating element heat up faster due to a decreased electrical resistance and greater current consumption.
  • a positive temperature 00- efiicient can be achieved by either (a) creating a temperature-dependent equilibrium between (i) the vapor pressure increase within the sealed optically transparent heating element due to increased temperature in an individual region of the heating element and (ii) solvent reabsorption by the electrolyte sheet upon cooling in the same region of the heating element or (b) through the use of a non-aqueous solvent for the electrolyte that has a pronounced temperature coefficient of the dielectric constant which over-compensates for the sharp conductivity in crease initially upon heating of the electrolyte resulting from the decrease in viscosity of the solvent.
  • the temperature-dependent equilibrium is achievable with electrolytes whose solvent possesses within the working temperature range (i.e. between about 35 C. and about C.) of the heating element of the present invention a sufficiently high vapor pressure, so that the solvent can evaporate from the electrolyte sheet in the envelope portion of the heating element.
  • aqueous solutions of salts, acids or bases diluted with water have a sufiiciently high vapor pressure so that the solvent will evaporate from the electrolyte sheet.
  • a highly hydroscopic compound e.g. magnesium perchlorate, concentrated phosphoric acid, etc.
  • Such a compound will also accelerate reabsorption of the evaporated solvent in those regions of the heating element which are cooling.
  • an optically transparent heating element one square meter which is blocked in one region would exhibit the same resistance over the entire remainlng region but would possess a higher resistance value in that locally blocked region due to an increased vaporization of the electrolyte solvent which results in on1y a slight and readily permissible temperature increase (if at all) at the blocked region.
  • the temperature After removal of the blockage from a region of the heating element, the temperature will decrease and the vaporized solvent will cool and be reabsorbed in the electrolyte sheet. This reabsorption will result in a decrease in resistance in the region and consequently an increase in current flow.
  • the resistance value of the heating element adjusts itself from place to place according to the temperature prevailing at each particular place. Therefore, overheating and hence burning or other damage to the heating element is completely eliminated because in every region of the heating element the resistance value automatically adjusts itself so that current consumpt on and hence the heat produced at that particular region does not permit the temperature thereof to increase beyond a desired maximum value.
  • the heating element maintains a regulated temperature regardless of change in surrounding conditions.
  • the same positive temperature coefiicient can also be achieved by using non-aqueous solvents which have a sharply decreasing dielectric constant with increasing temperature and which will over-compensate for the increase in electrical conductivity due to a sharp increase in ion mobility as the temperature increases.
  • the dielectric constant decreases, the impedance of the solvent to the flow of curernt increases.
  • a sharp decrease in electric current flow can be achieved with increasing temperature by using an appropriate solvent.
  • This foregoing characteristic of the solvent must over-compensate for the increase in electrical conductivity of the electrolyte which occurs upon heating of the electrolyte and produces an overall decrease in the electrical current flow with increasing temperature in the heating element, i.e., a positive temperature coefficient. If the solvent does not have a sharply decreasing dielectric constant with increasing temperature, over-compensation will not be achieved and hence a negative temperature coefficient condition would occur.
  • An optical-1y transparent electrical heating element comprising (1) insulating means having a pair of relatively flat side wall portions joined together, at least one dimension of said relatively fiat side wall portion being smaller than the corresponding dimension of the other relatively flat side Wall portion and (2) an electrolyte encased and sealed within said insulating means, said insulating means being substantially stable toward said electrolyte and said insulating means having opposed spaced electrically conductive means on the inside face thereof in contact with said electrolyte, a portion of said electrically conductive means extending outside of said sealed portion of said insulating means for connecting said heating element with an electric current source.
  • each of said side wall portions comprises a polymeric sheet material.
  • a heating element according to claim 1 wherein said side wall portions are sealed to each other to provide a substantially vapor-tight casing.
  • a heating element according to claim 1 characterized by a positive temperature coeflicient.
  • An optically transparent heating element having a positive temperature coefiicient comprising (1) a polymeric support material, (2) an electrolyte solution absorbed on said support material, and (3) insulating means substantially impervious to air and solvent vapors, substantially stable toward said electrolyte solution and en casing said electrolyte support material, said support material and insulating means each having opposed spaced conductive means in electrical contact relationship, a portion of said conductive means of said insulating material extending outside of the encased portion of said heating element for connection to an electric current source said heating element during the passage of electric current therethrough automatically increasing and decreasing the resistance of individual areas thereof in accordance with the dissipation of heat from said individual areas.
  • said insulating means includes a pair of relatively fiat side wall portions joined together, said electrolyte support material being encased within said side wall portions of said heating element.
  • a heating element according to claim 8 wherein at least one dimension of one of said relatively flat side Wall portions is smaller than the corresponding dimension of the other relatively fiat side wall portion.
  • a heating element according to claim 10 wherein said electrolyte support material is a polymeric material 12.
  • said electrically conductive means comprises spaced electrodes at least a portion of the respective electrodes of said insulating means and of said electrolyte support material overlying each other, and said electrodes of said insulating means being adapted to be connected to respective terminals of an electrical current source.
  • electrolyte foil according to claim 17 wherein said electrolyte solution contains a dissociation organic or inorganic acid.

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US733050A 1967-06-02 1968-05-29 Optically transparent electrical heating element Expired - Lifetime US3514581A (en)

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Application Number Priority Date Filing Date Title
AT512867A AT267702B (de) 1967-06-02 1967-06-02 Verfahren zur Herstellung durchsichtiger Flächenheizleiter aus elektrisch leitenden Kunststoff-Folien

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AT (1) AT267702B (Sortimente)
DE (1) DE1765464A1 (Sortimente)
FR (1) FR1587604A (Sortimente)
GB (1) GB1220748A (Sortimente)

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US3878362A (en) * 1974-02-15 1975-04-15 Du Pont Electric heater having laminated structure
US3878361A (en) * 1973-06-29 1975-04-15 Sierracin Corp Body covering and warming apparatus
US3898427A (en) * 1973-06-29 1975-08-05 Sierracin Corp Flexible warming structure
WO1982000935A1 (en) * 1980-08-28 1982-03-18 W Stumphauzer Electric heating device
US4883940A (en) * 1988-07-07 1989-11-28 Asc Incorporated Heatable composite backlight panel
US20020079225A1 (en) * 2000-10-30 2002-06-27 Kouhei Shiba Electrolyte solution for particle measuring apparatus, and particle measuring method using same
US6770848B2 (en) 2001-04-19 2004-08-03 William S. Haas Thermal warming devices
US20040256381A1 (en) * 2001-04-19 2004-12-23 Haas William S. Thermal warming devices
US20050007406A1 (en) * 2001-04-19 2005-01-13 Haas William S. Controllable thermal warming devices
US20050035705A1 (en) * 2003-08-11 2005-02-17 Haas William S. Illumination system
US6888101B2 (en) * 2001-05-31 2005-05-03 Respironics, Inc. Heater for optical gas sensors, gas sensors including the heater, and methods
US20050145796A1 (en) * 2001-05-31 2005-07-07 Ric Investments, Llc. Heater for optical gas sensor
US20060001727A1 (en) * 2001-04-19 2006-01-05 Haas William S Controllable thermal warming device
CN102316612A (zh) * 2010-07-08 2012-01-11 朱盛德 可挠式正温度系数发热元件以及其制造方法与运用
US20160044747A1 (en) * 2014-08-08 2016-02-11 Lincoln Dale Prins Modular anti-fog devices
WO2017189945A1 (en) * 2016-04-29 2017-11-02 NeoLight LLC Phototherapy apparatuses and methods

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GB2196215B (en) * 1986-10-15 1991-01-09 Jong Tsuen Lin Structure of electric heater

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US3020376A (en) * 1956-12-31 1962-02-06 Libbey Owens Ford Glass Co Laminated plastic articles and method of making the same
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US2543363A (en) * 1948-08-09 1951-02-27 William G Glendinning Electrically heated panel
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US2879367A (en) * 1955-04-25 1959-03-24 Douglas K Mclean Food package
US3020376A (en) * 1956-12-31 1962-02-06 Libbey Owens Ford Glass Co Laminated plastic articles and method of making the same
US3177345A (en) * 1961-06-02 1965-04-06 Glaverbel Lighting and heating device in the form of a panel
US3296641A (en) * 1962-09-28 1967-01-10 Fmc Corp Egg washer
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Cited By (25)

* Cited by examiner, † Cited by third party
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US3878361A (en) * 1973-06-29 1975-04-15 Sierracin Corp Body covering and warming apparatus
US3898427A (en) * 1973-06-29 1975-08-05 Sierracin Corp Flexible warming structure
US3878362A (en) * 1974-02-15 1975-04-15 Du Pont Electric heater having laminated structure
WO1982000935A1 (en) * 1980-08-28 1982-03-18 W Stumphauzer Electric heating device
GB2138255A (en) * 1980-08-28 1984-10-17 Frederick Gerrard Grise Electric heating device
US4485297A (en) * 1980-08-28 1984-11-27 Flexwatt Corporation Electrical resistance heater
US4883940A (en) * 1988-07-07 1989-11-28 Asc Incorporated Heatable composite backlight panel
US20020079225A1 (en) * 2000-10-30 2002-06-27 Kouhei Shiba Electrolyte solution for particle measuring apparatus, and particle measuring method using same
US7060203B2 (en) * 2000-10-30 2006-06-13 Sysmex Corporation Electrolyte solution for particle measuring apparatus, and particle measuring method using same
US6770848B2 (en) 2001-04-19 2004-08-03 William S. Haas Thermal warming devices
US20040256381A1 (en) * 2001-04-19 2004-12-23 Haas William S. Thermal warming devices
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US20060001727A1 (en) * 2001-04-19 2006-01-05 Haas William S Controllable thermal warming device
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Also Published As

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FR1587604A (Sortimente) 1970-03-27
AT267702B (de) 1969-01-10
GB1220748A (en) 1971-01-27
DE1765464A1 (de) 1971-09-02

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