EP0319079B1 - Elément chauffant en vitrocéramique - Google Patents

Elément chauffant en vitrocéramique Download PDF

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Publication number
EP0319079B1
EP0319079B1 EP88202637A EP88202637A EP0319079B1 EP 0319079 B1 EP0319079 B1 EP 0319079B1 EP 88202637 A EP88202637 A EP 88202637A EP 88202637 A EP88202637 A EP 88202637A EP 0319079 B1 EP0319079 B1 EP 0319079B1
Authority
EP
European Patent Office
Prior art keywords
layer
glass
phase
heating element
ceramic
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
EP88202637A
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German (de)
English (en)
French (fr)
Other versions
EP0319079A1 (fr
Inventor
Hughes Baudry
Marc Monneraye
Claude Morhaim
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.)
Koninklijke Philips NV
Original Assignee
Laboratoires dElectronique Philips SAS
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics 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 Laboratoires dElectronique Philips SAS, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Laboratoires dElectronique Philips SAS
Publication of EP0319079A1 publication Critical patent/EP0319079A1/fr
Application granted granted Critical
Publication of EP0319079B1 publication Critical patent/EP0319079B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
    • H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
    • H05B3/748—Resistive heating elements, i.e. heating elements exposed to the air, e.g. coil wire heater
    • 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
    • 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
    • H05B2203/017—Manufacturing methods or apparatus for heaters

Definitions

  • the invention relates to a glass ceramic heating element comprising at least one flat electric heating body applied to one face of a glass ceramic plate, this heating body including from this face a first insulating layer, a second conductive layer for forming power supply lines, and a third resistive layer to form a heating resistor.
  • the invention finds its application in the production of household appliances for which it is sought to associate a glass-ceramic plate appreciated for its ease of maintenance, with a heating stove at high temperature greater than or equal to 650 ° C.
  • the modulus of rupture of the ceramic glass decreases, particularly when these films include metallic constituents in combination with ceramic phases.
  • the cited document teaches that the glass ceramic exhibits a high resistivity even at high temperature, which means that no layer of electrical insulation should be necessary.
  • the present invention simultaneously poses and solves a problem which was hitherto completely unknown in the state of the art and which is as follows: When an electrical resistance is produced by screen printing on a glass ceramic material, then supplied with electricity to produce a heating element by thermal transfer, it appears that, at these high temperatures used in hotplate hearths, the glass ceramic support material becomes conductive electricity while the ceramic material alone retains a high resistivity. It therefore seems that the combination of a screen printed high temperature electrical resistance and a ceramic glass material is impossible to use for the production of a consumer hob, since it does not meet safety standards.
  • the present invention however solves this problem by providing a formulation for an electrically insulating layer at high temperatures and which also has a coefficient of expansion quite suitable for the glass-ceramic support at these high temperatures.
  • the insulating layer a material comprising an excessively large vitreous phase, or a material whose ceramic phase decomposes at high temperature to supply glass, this glass tends to rise in the resistive layer and, coating conductive particles, to cause the temperature coefficient to decrease, possibly even causing this temperature coefficient to become less than O. This would then lead to rapid deterioration of the heating element, leading to breakdown of the resistance.
  • the present invention solves this problem by providing an insulating layer which does not react at high temperatures with the resistive layer.
  • this insulating layer is produced by screen printing from a starting mixture for screen printing ink comprising on the one hand: a glassy phase consisting in molar proportions of: ZnO + MeO 50 to 65% WHERE 10 to 20% Al2O3 0 to 10% If 40 to 5% in which MeO is an oxide chosen from refractory oxides such as: MgO, CaO, and in which MeO is associated with ZnO in the molar proportions 0 to 10% of the whole of the glassy phase such that the proportions ZnO + MeO constitute 50 to 65% in moles of said glassy phase, and comprising d on the other hand an amorphous phase formed of a
  • the heating resistor is perfectly insulated at high temperatures, its temperature coefficient is positive and the entire device supports aging well.
  • a ceramic glass hob comprising an electric heating body arranged in the form of a spiral below the plate as well as a thermostatic probe thermally coupled to the baking plate. inside the cooking surface area. On the marginal zone of the cooking surface is provided an unheated zone for the thermal coupling of the probe, the rest of the surface being covered of the two-wire heating element, the connections of which are located on the periphery of the cooking surface.
  • a cooking plate thus equipped offers several disadvantages.
  • First of all the heating device is always of a high price because it is of a complex assembly. Then it is located at a certain distance from the ceramic hob, which leads to heat losses. Thus, it is subjected to a time constant for cooling and heating mainly due to poor thermal conduction of the air, which makes this kind of hob less flexible to use than hobs with adjustable flames. for example.
  • the present invention provides a heating element which is free from this type of drawback, since the heating resistor is directly in contact with the ceramic hob.
  • the invention presents a new formulation for a high temperature resistive ink. Indeed, it was also necessary that the coefficient of expansion of this ink, at the firing temperature, or at the temperature of use, be as close as possible to that of the glass-ceramic support, which is practically zero. This is difficult to achieve for a resistive material which contains conductive particles. The invention however solves this problem.
  • the glass ceramic heating element comprises a glass ceramic support plate 10 serving to work surface on its upper face 11, and substrate for the heating element 20 on its lower face 12.
  • Such a heating element has the advantage of forming a very smooth work surface and therefore easy to clean, as not showing any crevices, into which solid or liquid food particles can be introduced, for example, from the overflow of culinary containers.
  • This very flatness is an advantage for receiving the culinary containers which always rest in a very stable manner on the work surface, which allows good heat exchange.
  • the underside 12 of the ceramic hob is coated with at least one heating hearth constituted by a heating element as shown seen from above in FIGS. 2.
  • the ceramic glass material has been chosen to date to produce cooktops because of its aesthetic appearance, the practical qualities mentioned above, and above all because of the fact that it has a zero coefficient of expansion which makes it very resistant to thermal shock.
  • it has the disadvantage of being a poor conductor of heat, which means that, if the heating element is at all slightly away from the surface to be heated, there is a considerable temperature gradient in the air.
  • the advantage provided by the present invention which makes it possible to produce a heat source for the heating hearth in direct contact with the ceramic hob, which reduces the thermal resistances.
  • the poor thermal conductivity of the glass-ceramic material is used as an advantage to preserve between the hotplates, outside each heating hearth, non-hot zones, where electrical contacts can be made at leisure with traditional welding materials, therefore cheap.
  • an insulating layer 21 is first deposited directly on the surface 12.
  • This material is developed to first present a coefficient of expansion practically identical to that of the plate 10 and that of the upper layers 23, and that at the highest temperatures.
  • This material is also developed to present excellent electrical insulation at these same high temperatures.
  • This material is finally produced so that it does not diffuse into the resistant layers 23 either at cooking temperatures or at high temperatures, thus avoiding changing the temperature coefficient (CTR) of the resistant layers during aging.
  • CTR temperature coefficient
  • Curve C I in Figure 5a shows the relative linear variations ⁇ l l of the insulating material 21 as a function of the temperature T, and the curve C V of FIG. 5b shows the corresponding variations of the glass-ceramic material 10 at the same temperatures. These curves are both very close to 0.
  • the insulating material 21 is deposited over the entire surface of the zone constituting the heating hearth of the cooking plate.
  • Figures 3 and 4 which are respectively schematic layers of Figures 2 along axes I-I and II-II show that the insulating layer 21 is a uniform layer of thickness 100 microns or more.
  • Two supply lines C1 and C2 for the electrical supply of the heating element are produced in the form of a screen-printed ribbon in a layer of thickness approximately 50 ⁇ m, depending on the applied voltage and the desired temperature, on the surface. of the insulating layer 21. These lines are formed of a conductive compound 22.
  • a resistive compound 23 deposited in a screen-printed layer of thickness approximately 10 to 50 ⁇ m.
  • the resistive material constituting the layer 23 is designed to have a coefficient of expansion as close as possible to that of the glass-ceramic material at high temperatures.
  • Figures 2 show two advantageous diagrams of the arrangement of these resistive ribbons between the supply lines. These diagrams are given purely by way of example, since the method for producing the heating element according to the invention is very flexible to use and makes it possible to carry out absolutely all types of configuration for this kind of circuit.
  • the circuit can thus cover a hearth forming a square area as illustrated in FIG. 2b, rectangular, oval or circular as illustrated in FIG. 2a. It may moreover be free according to the request of the consumer, or customer, to produce a cooking plate provided with several hearths showing a different shape. In addition, all the areas of hearth surface are achievable, and not only the surfaces with the two standard diameters currently marketed.
  • the circuit according to the invention being produced on the lower face 12 of the ceramic hob, the upper face 11 serving as a work surface remains blank.
  • the circuit can also be produced in small dimensions on a ceramic glass support to serve as a plunger heating element; for example to quickly bring a liquid to a given temperature.
  • the circuit can then be coated with an upper insulating layer 24 similar to layer 21.
  • the supply terminals are also fitted with waterproof and insulating sleeves like any conventional heated plunger.
  • the heating element according to the invention can also be used to make a high or low heating plate (floor or ceiling) in a convection or fan-assisted oven, or else in a multi-microwave oven.
  • the lines C1 and C2 are extended sufficiently so that their end is placed in a relatively cold zone.
  • a few centimeters are sufficient to bring the lines C1 and C2 to an area where the temperature will always be low enough for the glass ceramic support material to be absolutely non-conductive of electricity.
  • the insulating layer 21 is interrupted under the layer 22 which constitutes these terminals so that this layer 22 is in direct contact with the glass-ceramic material.
  • the layers 21, 22, 23 and possibly 24 are produced by a screen printing technology by means of compounds whose formulation is given below.
  • the mixture comprises a glassy phase consisting of the molar proportions of the following oxides: If 30 to 55% ZnO 20 to 40% WHERE 0 to 20% Al2O3 0 to 10% SrO, BaO, CaO 5 to 40% CoO 0 to 10% and ceramic phase consisting of ZnO + CoO, the glassy phase accounting for 85 to 60%, and the ceramic phase accounting for 15 to 40% by volume of the mixture.
  • this mixture has a coefficient of expansion at high temperature which is close to that of alumina, that is to say very far from that of the glass-ceramic material itself.
  • a starting mixture for a screen-printing ink capable of producing layer 21, that is to say both insulating at high temperature, with a coefficient of expansion close to that of the glass-ceramic material, and not diffusing into the upper resistive layer will firstly comprise a glassy phase constituted in molar proportions by: ZnO + MeO 50 to 65% WHERE 10 to 20% Al2O3 0 to 10% If 40 to 5% in which MeO is an oxide chosen from refractory oxides such as MgO, CaO, MeO being associated with ZnO in molar proportions 0 to 10% of the entire glass phase and such that the proportions ZnO + MeO constitute 50 to 65 % in moles of said vitreous phase.
  • a glassy phase can be found, made up in molar proportions of: ZnO + MeO 62% WHERE 17% If 21%
  • the starting mixture for such an insulating composition will also comprise an amorphous phase.
  • the glassy phase and the amorphous phase are associated in volume proportions such as: Glassy phase 3 to 13% and preferably 5% Amorphous phase 97 to 87% and preferably 95%.
  • the amorphous phase will consist of amorphous silica chosen for its low coefficient of expansion.
  • a glass is first of all produced, the molar proportions of which correspond to the ranges indicated above or to one of the examples cited.
  • the glass thus obtained is ground.
  • this operation is incorporated to obtain a homogeneous mixture the powder forming the amorphous phase in the chosen volume proportions.
  • This grinding can be carried out in a liquid medium such as water.
  • the result of the grinding is then dried and then dispersed in an organic vehicle.
  • an organic vehicle capable of making this starting mixture screen-printing it is possible to use a solution containing a polymer, for example a solution of ethylcellulose in a terpineol or a mixture based on terpineol.
  • This organic vehicle can represent before cooking 10 to 40% of the weight of the screen-printing ink.
  • the proportions of the organic vehicle relative to the ink are chosen according to the desired rheological behavior.
  • none of the materials chosen to make the heating device on ceramic glass presents the risk of oxidizing in air, the ink is baked in the open air. The organic vehicle is thus consumed using oxygen from the air.
  • Cooking at around 900 ° C. is carried out in a so-called pass-through oven for about 10 minutes.
  • the composition of the glass is not intended to constitute a heating resistance, and more particularly a heating resistance capable of being brought to 650 ° C. by the Joule effect, and of presenting a positive CTR and which remains so in aging.
  • a starting mixture for a screen-printing ink capable of producing the layer 23, endowed with this property and with a coefficient of expansion close to that of the glass-ceramic material will firstly comprise an active phase consisting of volume proportion of the total mixture of: RuO2 ⁇ 15 to 40% and in particular preferably ⁇ 30% CuO ⁇ 0 to 5% and a glassy phase made up of a composition similar to that of melted vitroceram and quenched in volume proportions complementary to the above mixture.
  • the glass melts ensuring the function of binder then during this same cycle recrystallizes from vitroceram.
  • the glass-ceramic thus formed makes it possible to obtain the appropriate coefficient of expansion.
  • the CTR of this resistance when it is carried out with the preferred proportions, is: + 520 ppm ° C ⁇ 1 between 20 and 300 ° C and + 150 ppm ° C ⁇ 1 between 300 and 650 ° C.
  • the glassy phase is ground and the oxides constituting the phase active are incorporated as it was said previously for the production of insulating ink. Following this, the mixture is incorporated into a rheological vehicle already described.
  • a screen-printing ink capable of producing lines C1 and C2 in layer 22 will be formed in one example of a silver powder (Ag) + palladium (Pd) or platinum (Pt), or even in another example of a silver powder (Ag) alone, to which a small proportion of copper oxide (CuO) is added, this powder then being incorporated into a rheological vehicle as described above.
  • a silver powder Ag + palladium (Pd) or platinum (Pt)
  • CuO copper oxide
  • Table II starting mixture for resistive layer 23 Composition of the mixture in volume proportions
  • Preferred example General composition Glassy phase composition similar to vitroceram ⁇ 65% 100% supplement RuO2 ⁇ 30% ⁇ 15 to 40% CuO active phase ⁇ 5% ⁇ 0 to 5% starting mixture for conductive layer 22 Composition of the mixture in volume proportions
  • Example I Example 2 Ag 80 to 100% Ag 80 to 100% CuO 20 at 0% Pd / Pt 20 to 0% CuO in complementary proportions

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Surface Heating Bodies (AREA)
  • Resistance Heating (AREA)
EP88202637A 1987-11-24 1988-11-23 Elément chauffant en vitrocéramique Expired - Lifetime EP0319079B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8716255 1987-11-24
FR8716255A FR2623684A1 (fr) 1987-11-24 1987-11-24 Element chauffant en vitroceramique

Publications (2)

Publication Number Publication Date
EP0319079A1 EP0319079A1 (fr) 1989-06-07
EP0319079B1 true EP0319079B1 (fr) 1993-09-29

Family

ID=9357094

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88202637A Expired - Lifetime EP0319079B1 (fr) 1987-11-24 1988-11-23 Elément chauffant en vitrocéramique

Country Status (5)

Country Link
US (1) US4973826A (ja)
EP (1) EP0319079B1 (ja)
JP (1) JP2661994B2 (ja)
DE (1) DE3884569T2 (ja)
FR (1) FR2623684A1 (ja)

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DE4022845A1 (de) * 1990-07-18 1992-01-23 Schott Glaswerke Temperatursensor oder -sensoranordnung aus glaskeramik und kontaktierenden filmwiderstaenden
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JPH05198356A (ja) * 1991-02-26 1993-08-06 Lapin Demin Gmbh 平面発熱体及びその製造方法
KR0146624B1 (ko) * 1994-12-19 1998-09-15 김광호 신용거래용 카드 및 이를 이용한 신용거래장치 및 방법
US5657532A (en) * 1996-01-16 1997-08-19 Ferro Corporation Method of making insulated electrical heating element using LTCC tape
US6037572A (en) * 1997-02-26 2000-03-14 White Consolidated Industries, Inc. Thin film heating assemblies
US5973298A (en) * 1998-04-27 1999-10-26 White Consolidated Industries, Inc. Circular film heater and porcelain enamel cooktop
DK0967838T3 (da) * 1998-06-25 2005-11-28 White Consolidated Ind Inc Tyndfilmsopvarmningsanordninger
DE19836148A1 (de) * 1998-08-10 2000-03-02 Manfred Elsaesser Widerstandsflächenheizelement
DE19855481A1 (de) * 1998-12-01 2000-06-08 Siceram Gmbh Elektrisches Kochfeld
US6225608B1 (en) 1999-11-30 2001-05-01 White Consolidated Industries, Inc. Circular film heater
US6534751B2 (en) * 2000-02-28 2003-03-18 Kyocera Corporation Wafer heating apparatus and ceramic heater, and method for producing the same
EP1233651A1 (en) * 2000-04-07 2002-08-21 Ibiden Co., Ltd. Ceramic heater
WO2001084887A1 (fr) * 2000-04-29 2001-11-08 Ibiden Co., Ltd. Plaque chauffante en ceramique
DE10111734A1 (de) * 2001-03-06 2002-09-26 Schott Glas Keramisches Kochsystem mit Glaskeramikplatte, Isolationsschicht und Heizelementen
DE10112236C1 (de) * 2001-03-06 2002-10-24 Schott Glas Keramik-Kochfeld
DE10110792B4 (de) * 2001-03-06 2004-09-23 Schott Glas Keramisches Kochsystem mit Glaskeramikplatte,Isolationsschicht und Heizelementen
WO2002104073A1 (fr) * 2001-06-19 2002-12-27 Ibiden Co., Ltd. Plaque chauffante en ceramique
DE10225337A1 (de) * 2002-06-06 2003-12-24 Schott Glas Kochsystem mit direkt geheizter Glaskeramikplatte
US20050167414A1 (en) * 2004-01-30 2005-08-04 Po-Chun Kuo Cooking device with a thick film resistive element heater
US6991967B2 (en) * 2004-02-23 2006-01-31 Asm Assembly Automation Ltd. Apparatus and method for die attachment
JP5005673B2 (ja) * 2005-03-25 2012-08-22 ヘンケル コーポレイション 家庭用電気器具を組み立てるための組成物および方法
EP2906083A1 (en) * 2012-10-11 2015-08-19 Arçelik Anonim Sirketi A wireless cooking appliance operated on an induction heating cooktop
CN103731940A (zh) * 2012-10-16 2014-04-16 张鸿鸣 微晶发热体和金属微晶发热体
TR201408916A2 (tr) * 2014-07-25 2016-02-22 Bsh Ev Aletleri San Ve Tic As Bir elektrik iletim elemanına sahip bir pişirici cihaz.
KR101762159B1 (ko) * 2016-02-24 2017-08-04 엘지전자 주식회사 면상 발열장치, 이를 포함하는하는 전기 레인지 및 그 제조방법
KR102111109B1 (ko) * 2017-02-21 2020-05-14 엘지전자 주식회사 면상 발열장치, 이를 포함하는 전기 레인지 및 그 제조방법
US10917942B2 (en) 2017-07-31 2021-02-09 Samsung Electronics Co., Ltd. Structure, planar heater including the same, heating device including the planar heater, and method of preparing the structure
CN108684089A (zh) * 2018-04-20 2018-10-19 江苏澳盛复合材料科技有限公司 一种加热板
KR102159802B1 (ko) * 2018-08-21 2020-09-25 엘지전자 주식회사 전기 히터
KR102123677B1 (ko) 2018-08-21 2020-06-17 엘지전자 주식회사 전기 히터
KR102091251B1 (ko) * 2018-08-21 2020-03-19 엘지전자 주식회사 전기 히터
KR102056084B1 (ko) 2018-08-21 2019-12-16 엘지전자 주식회사 전기 히터
US11825568B2 (en) * 2021-04-01 2023-11-21 Whirlpool Corporation Segmented thermoresistive heating system

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FR2490210A1 (fr) * 1980-09-15 1982-03-19 Labo Electronique Physique Melange de depart pour une composition fortement resistante, encre serigraphiable constituee avec et circuits electriques ainsi realises
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DE3536268A1 (de) * 1985-10-11 1987-04-16 Bayer Ag Flaechenheizelemente

Also Published As

Publication number Publication date
US4973826A (en) 1990-11-27
JP2661994B2 (ja) 1997-10-08
EP0319079A1 (fr) 1989-06-07
FR2623684A1 (fr) 1989-05-26
JPH025392A (ja) 1990-01-10
DE3884569D1 (de) 1993-11-04
DE3884569T2 (de) 1994-04-07

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