DE1937875A1 - Cooking device with integrated heating element - Google Patents

Description

1937 * 75

M 2555

fl HAN3 RU8CHKE DlpL-lno. HEINZ A0ULAH

BERLIN 33

Minnesota Minin ·; and Manufacturing Company, Saint Paul, Minnesota !! - "ΙΟΙ, V.St.A.

Cooking device with integrated heating element

This invention relates to cooking utensils which have integrated thin resistive or heating element films composed of a porcelain glaze frit material and silver oxide (or other precious metal particles) with a volatile, non- carbonizing organic binder. The particles of the Porzellanglaeur-Pritte material are at least five times larger than the silver oxide particles, which form the conductor of the heating element. The wet is fired onto the OerKt, and during the firing the silver oxide is converted to silver metal in the form of finely divided particles, each particle less than 1 micron in diameter.

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1937679

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It is well known in the art to use fine metal powders or particles to combine with a glass frit material. However, such masses are of value only with very limited changes in composition. A very small percentage change in the amount of frit material and particles, or the powder causes a mass to be made either excessively conductive or electrically non-conductive. These Technological masses also provide narrow electrical conduction paths, like that that when used as a heating element for a cooking appliance, the surface to which heat is transferred is on the part of the '"ierätes is limited directly to the electrical Adjacent route.

In this invention, the porcelain glass fiber particles, which lie in a greater size than silver oxide Particles, a heating element film created under the Extensive variations in the percentage of the frit material and the conductive particles can be expanded. The film can also be designed as a guide sheet and later on the Surface of a cooking appliance can be applied and fired as an integral part of the same.

Although the frit particles have an "average particle size" five times or more than the metal particles (ie, Ag ₂ O), it is possible that a small portion of the frit particles may be of the same size as the metal particles can. The reason why the healing learning process is so effective from this mass is not completely clear, but after the burning process the porcelain glass can be loosened from the embedded heights, and it is preserved in a fragile network. The network appears to be composed of innumerable tiny super-bonds that touch each other, but that are not generally fused or sintered together into relatively massive strands,

Because the super particles are a multitude of parts

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BATH ORIGINAL

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form with each other in the network, the heating elements are not subject to mechanical or electrical breakdown. Breaking even several contact points does not lead to such a load on parallel contact points that a melting through or collapse of the Heating element would be caused. Instead, the load is slightly increased at each contact point. The calls only when a substantial number of contact points are interrupted electrical load causes a breakdown.

In the areas of the heating element film where direct contact with an electrical power source is made, there may be a relatively high current density and the contact points may have a tendency to burn through · This problem is circumvented by using graded electrical Terminals in which a metal-rich Ground applied to the contact points with the power source will.

Whenever Meta11 cooking appliances are used, the first thing to do is a glass-like glaze dielectric or insulation layer can be applied to the surface of the metal device. Of the Heater film is then bonded to the dielectric layer. A glass-like ProEellan dielectric layer made from Lead borosilicate and quartz crystals is composed, represents represents a highly satisfactory insulator between the netal surface of the cooking appliance and the heating element film them in U.S. Patent 2 * 77 121 of July 26, 19 * 9 and U.S. Patent 2,859,521 dated Nov. 4, 1958 become the most satisfactory insulating properties Not used by lead borosilicate. Lead borosilicate has one comparatively low viscosity when exposed to the firing temperatures necessary for glazing and when the dielectric layer is attached to the cooking appliance · As a result The lead borosilicate tends to over-run during firing

909888/1106

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■ Metallic surface of the device on which it is applied is to flow or hike. To have a suitable viscosity to achieve during the fusing, without the dielectric properties of the lead boron or its expansion coefficient to change, are tiny quartz crystals according to the invention used as an additive to a blelborosilicate frit material. By adding quartz crystal to the frit material the viscosity achieved is sufficient for the mass obtained, so that it has any tendency to flow or wander resists during firing.

When using metal cooking utensils, it is preferred to use thin metals such as mild steel, which is a low one Has heat capacity, so that most of it through the heating element film generated heat is dissipated directly to the food contained in the cooking appliance.

Understanding of the invention will be facilitated with reference to the accompanying drawings in which like numbering refer to identical parts in the drawings and in which:

Figure 1 is a three-component diagram in percent by weight of the different compositions presented in heating elements]

Figure 2 shows a sectional view of a cooking appliance in which the dielectric layer and the heating element are bonded to each other and to those carrying the food Part of the cooking appliance are bound i

Figure 3 is a perspective view of the bottom surface of a another shape of the cooking appliance and the dielectric Figure 13 shows the layer and the heating element attached thereto; and

Figure 4 is a sectional view of the cooking utensil of Figure 3 taken along the lines and in the direction of arrows 4-4 of Figure J with the cooking utensil carried on a stand.

^ ^ ioieee / 1ro

BATH ORIGINAL

- - · ..- 1937 * 79

- 5 - M 2655

Regarding the element films are separated in FIG Coarse and fine fry ingredients are used for the sake of simplicity has been used ura more clearly to illustrate the effects of variations in the proportions of frit particles that much coarser than the silver oxide particles are. Coarse frit materials In percentages are on the left of the diagram of Figure-1 and fine F.rlt te -Materia Ii en in percentages the right side of the diagram of Figure 1 can be seen. The base line of the diagram shows the percentage of silver oxide particles.

It can be seen that the3 generally broader compositional ranges are effective if you use the relatively coarse frit -Material used instead of the finer Frit te-Materia Is. That finer frit material is nonetheless crude in comparison to silver oxide. The usual combinations of technology are produced in such a way that · the metallic component similar in size to the coarsest FrItt "-TeHehe" will.

The preferred masses of the invention are those in the general field ABCD and from the outermost edges AB and CD distant are those that are neither quite coarse nor whole fine but average and more of a simple ground one Frit te material are similar. In the figure represents the line AD grounds with essentially infinite resistance and the line BC grounds with a resistance of approximately 1 ohm in the size of the conductor shown. If enough points are determined it is very possible that these lines could tilt or bulge to a certain extent. It is revealing that such a diagram is Kusserst specific and that other diagrams are designed from many specific combinations of frit materials and conductors experiment * 11 based on the teachings given here and that empirical differences are likely to be found.

BATH

909886/110

1937973

-.6 - M 2535

The aim is specifically the use of coarser Frltt, e-particles than veranscuaulichen the metal particles. It is believed that so far no one has recognized that such a wide range in the composition can be used, furthermore a great mobility with regard to the electrical parameters with simple maintenance the intended key parameters for the dimensions and watt range is permissible. So it is clear from the graph that broader compositional areas are more usable than "they were before, if you use glassy frit materials at a low temperature which were ground to be generally as fine or finer than the Meta 11 particles. Here one appears Advantage when using coarser frit materials and recrystallizing ones Porcelain glazes to lie on.

In FIG. 1, the peaks of the diagram are denoted by 100% of the corresponding constituents, the increasing percentages of which are shown along the adjacent side lines. Of course, each peak also means 0 % for the other two components. The various points represent grounds provided with the resistance in ohms of an element about 125 cm long, about 5 mm wide and about 0.125 mm thick, as will be described below. These resistors are conveniently referred to as element specific resistances It can be seen that the specific element resistances increase at lower 3 over kept sohneil and over 50-60 % silver to the point where they _{decrease overly conductive sini 4.} It is clear that any desired combination of properties Herding can be achieved within these teachings using greater or lesser amounts of porcelain enamel frit materials, depending on the desired resistance of the thickness, width and length of the conductor.

The silver oxide used in these compositions is average Particle size of 1 micron for smaller particles

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up to 0.5 microns and occasional particles up to about 2 microns generally useful and preferred in such masses.

Such a material is readily available in chemically pure grades.

The preferred matrix material is a porcelain glaze that is compatible with the base layer, such as a dielectric or insulating layer, to which the helmet element is to be attached. A commonly available and universally usable glaze is a glaze with a medium phosphate content, which contains about 1 1/2 to 20 % titanium oxide. Such a typical mass is:

Weight percent

Drained borax 19.1 quartz 42.0 Sodium nitrate 7.8 Sodium halide fluoride 1.2 Potassium silicofluoride 7.8 anhydrous sodium monophosphate 3.2 Titanium oxide 18.9

As far as is known, the composition is not deodorant as such, although it is characteristic that the masses recrystallize and at a sufficiently low temperature mature so that the metal parts do not deteriorate and rusaanenfliess «n. So is the glaze for the metal particles not flowing. It is at least possible that recrystallization of the titanoid opacifier may decrease the flux can. In any case, a porcelain glaze is preferred -Frit material in bulk for the manufacture of the heating elements to use the rait related Meta11 devices used will.

909866/1106

1937 * 73

- 8 - M 2655

The Pritte materia lien are usually obtained a la glass-like flakes or granules, which have to be ground and then get the particle size distribution. In order for them to be effective for the compositions of the invention, the proportions of the ground Pritte material must be predominantly (usually 80-85 % ) greater than the average size of the metal particles by a factor of 5 or more. The frit material can be ground by any conventional method. It can be convenient to sieve the coarsest particles out of the frit material and then further grind them into smaller portions. For the compositions used to design Figure 1, the coarse particles ranged from 53 to 105 microns in the diameter gauge. The frying material used for the fines was extensively ground (in ethanol for 5 hours or more) to achieve a size range of less than 1 to 5 microns, with some particles up to 10 miron.

A particularly useful embodiment of the invention consists of transfer sheets made of frit material that can be placed on a cooking appliance and burned on site. This lowers some valuable manufacturing conveniences. In this embodiment, frit material of suitable particle size and silver oxide are combined with an organic binder that decomposes when heated without coking or charring, in addition to a solvent for the binder. A small amount of plasticizer may optionally be included. The thick mass is poured to a desired thickness or applied with a knife, for example 0.05 to 3 mm on a smooth support such as QIb, polished metal, silicone polythene-impregnated paper or a polymeric film. The solvent is then evaporated. Of course, because of the valuable Meta11 contents of these compositions, thinner films are preferred. However, it should be noted that ^N, a much lower metal content, may be useful in a relatively thicker film. Thinner films down to about 0.01 mm are conventionally placed directly on a device or for transferring documents under

909886/1101

BATH ORIGINAL

1937_87SL_

- 9 - -M 2655

Made using silk screen process.

In this embodiment, it appears that the particle size range of the frit material helps anchor the silver particles so that they do not separate or settle under the influence of gravity during drying. The binder also delays the separation of the silver particles so that a homogeneous suspension is maintained. For example, the compositions used to design Figure 1 were made from 100 g of the dry combination in the various proportions (as shown in Figure 1 ) of frit materials and silver oxide, which were dissolved in a solution of 20 g of polyisobutylene (having an average molecular weight of 120,000) were suspended in 50 ω tolud ^1. Other binders can also be used as alternatives or other solvents. The mass is applied with a knife to form a film about 0.5 mm on a silicone-treated paper backing sheet and air-dried. Degassing can be applied to the suspension before application; however, it is not necessary in most cases. The inclusion of air bubbles in the Rrzellanglaze is often taken into account in order to provide a measure of the relaxation of the tension.

After drying, the film of the mass forms a heating element film, who look around himself does rolls for storage and later Use rolled up or used directly.

It is convenient to "read the Heise t-Pi la su butter to cut" for example 7 # 5 x 12.5 cm, which fit a special cooking device or are suitable for creating a heating element film with a special outlet. When the base on which the film is cast. Is glass or metal, the film must first be sucked off. On the other hand, when pouring onto treated paper or polymer film as above, the backing can stay on and provide additional support; ssie will

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1937873

after the film has been transferred to the device on which it should adhere, removed.

The Heizele.nent film, for example in the geachnit.tenen sheet, becomes a sleek or meandering heating element made by making appropriate surface cuts, to subdivide the surface into the desired areas, which can be arranged so that contact endpoints are at opposite ends or the same ends or in others desired positions by placing the film in incised in a conventional manner, such as with a Nesser or pressed, dressed (dinking) or otherwise · processed will. It is not absolutely necessary for the cuts to go all the way through the film, as natural shrinkage occurs during firing can lead to further opening of the incisions. Still burns the measured current passed through weak junctions and leaves behind a fragile network of metallic conductors, that is intact in those parts where the film is not cut was. As a result, cuts can be made in the film, while a backing sheet is retained for support. .Cuts can also be made to have a shape created that is easily a cooking appliance with a non-planar Surface can be customized by cutting away certain parts and cutting into other parts. This mode of operation allows easy application of integrated heating elements on the undersurface and / or - rare of cooking utensils.

If Meta 11 cooking equipment is used «ground« lit please note that the elements are applied to a · dielectric · or I »oll * r« ohlont, which is attached directly to the cooking appliance, to form an insulation between the Heixeleroent film and the metallic cooking appliance.

For example, the rectangular one, generally marked 10 in Figure 2 designated cooking appliance a metal bowl 11 with a dielectric layer 12 of a defined surface area, which on its

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Lower surface or the seldom sits. A heating element film 13, which consists of the film compound described above, is bonded directly to the dielectric layer 12. The metal bowl can be embedded in a base layer 14 made of non-conductive material (such as polysulfone) and a suitable cover layer 14b over the oround layer 14. A 10 om om χ 15 rectangular cooking appliance with 2.5 cm depth of the kind shown in Figure 2 is for cooking and serving of individual meal "large-scale IT en portions airborne food or feed or in food service cart of the railway useful.

Meta Ils chUs se in any configuration can be used. For example, Figures 3 and 4 illustrate a bowl-shaped cooking appliance, indicated generally at 10a, having a shaker 11a. The dielectric layer 12a is attached to the bottom part of the bowl 11a, and the heat element-fi Im 13 is bonded to the dielectric layer. The cooking appliance 10a of FIGS. 3 and 4 is carried by an orund sole 14a, because the bowl 11a is supported without coming into contact with the heating element film 13a. '.

The dielectric layers 12 and 12a are essentially glass-like porcelain made from lead boron-coated with tiny Quartz crystals exist, which are bound close to each other and to the iborosilicate.

Both the lead boron icate and the quartz crystals have strong dielectric properties. Thus, a dielectric layer of this composition does not bring a significant number migrating ions emerge when brought to normal cooking temperature areas is heated. Alkalis such as sodium, potassium, lithium, etc., previously used as a mass for electrically insulating vitreous Glazes used generate significant amounts of migrating ions in the cooking temperature ranges; they create so a possibility for electricity spanking between the metallic

Cooking device and the heating element. A glass-like porcelain dtelek;

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1937873

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tricum layer made of lead borosilicate closes this possibility the end.

A frit material composed of lead borosilicate is difficult to hold in a defined area on a metal surface during melting * because it is flowable and when it is exposed to the firing temperatures, it is subject to an unregulated flow. To this problem too correct, quartz crystal He is added in about 25 to 60 Qewiohtsteile to the frit material to increase the viscosity of the Increase borosilicates during firing. A very "A large proportion of the crystals does not dissolve in a glass,

when the blelborosilicate is melted and during Brennens merges. The crystals remain defined and give the molten lead borosilicate during glazing Mass or physical adherence, ao that mass does not have the Surface of the metal * to which it is applied flows " During qiaslerena the crystals fuse together and with the lead borosilicate and form a glazed porcelain.

In addition, the expansion coefficient of the quartz crystal He is essentially the same as the expansion coefficient for the lead borosilicate, and therefore additional additions ₍ for adjusting the expansion coefficient of the crystals

not necessary on the BIe! borosilicates.

Made from a blelborosilicate and tiny quartz crystals compound Dlelektlkua-Sohloht 12 or 12a has very good physical and dielectric properties in temperature ranges from 177 - 288 ° C. The Dlelektlkum-Sohloht breaks does not collapse or break through at this temperature. Ee there is no significant current slip from the heating element through the dielectric layer and onto the metal surface of the cooking appliance 11 or Ha. For example, was through earth the surface of the bowl Ha when heated to a temperature of 233 ° G and when 120 volts to the heating element film are applied, no current drain to earth found.

809886/1106

BAD ORIQtNAt

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Mathematical calculations result in Rinon's speculative contradiction. - stood for the Die'lck'r.rikum layer -12 ^ of over-; r 10? Ohm'. σ; η. For practical purposes there is thus no current drain through the layer 12a for the bowl 11a, which is the case with the dielectric sohioht Coated cooking utensils are completely usable.

The dielectric layer 12 or 12a is made in the same way divided like conventional glass-like glazes. A lead one Glass frit material having the following composition ^ in percent, the following is used:

PbO. 83.0 %

B ₂ O,. 10.0 % ■■■ - ■ - ■

SiO ₂ . 7.0 % ■. ■. ■. ■ .-

The mass is ground to a fine powder such as particles in a size range below 50 microns. An amount of milled ^ uarz-Kris ta Ilen with a diameter of 7 ^ microns, and preferably in the wt I tsmenge the frit Ma terials äiulvalfcnten weighting- tsmenge is added. To obtain the desired viscosity at the transition of Frltte-Materlals in molten 'j read to bring forth. . The mixture of frit and Ma TERIAL, Luarzi Kris-ta Ilen is so preferably 50 wt _e - # te-frit material and 50 wt .- ^ crystals, However, it has been found that a mixture of 25 50 parts by weight ^ Quars crystals and 40 - 75 Qew.-jS frit material an insulating layer with acceptable dielectric properties results in clay in an amount of 3 % de »Komblnationasewi ^ htea also. Frit material and the crystals are added to the mixture together with electrolytes or salts in an amount of 1 % of the combined weight of the frit material and crystals. Enough water is added to provide an aqueous mixture with a specific gravity of approximately 1.8.

To apply the dielectric layer 12 or 12a, the The lower surface of the bowl 11 or 11a is suitably

909886/1108 * " ^0F " ^QINAl

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etches, and a satisfactory basic coating for binding the, Dielectric layer is applied over the prepared surface sprayed. The aqueous mixture of lead borosilicate cold,. The material and quartz crystal is then made to the desired Area and structure on the. Spray base coat 150-250 microns thick and then dry calmly. After the applied .Qeralache has dried approximately 3 minutes at 788 °. C. under normal atmospheric pressure fired and cooled to room temperatures. While burning give the quartz crystal to the molten blelborosllicate sufficient viscosity so that this »on the application surface area remains held. . ......

The carbon borosilicate frit material alone has an expansion coefficient of approximately 11.1 10 degrees, and is slightly higher than the expansion coefficient for fluo steel, which is 10 × 10 degrees. It dissolves during firing and glazing a. small percentage of the quartz crystals in the f3lelboro3illka t and thus lowers the expansion coefficient of the obtained Pprzellan-Dielelctrlkum-ochioht to 12 to ) _t Z> χ 10 " ^J (degree C" ¹ ). The expansion coefficient of the 3 steel bowl 11 or 11a is therefore slightly larger than that of the dielectric layer. The larger coefficient of expansion j of the steel nut exerts a slight compressive stress on the layer! L2 or 12a if I close the shells while cooling down from the firing temperature. The compressive stress increases the bond to the steel, and so an extremely satisfactory "seat" is created between the layer 12 or 12a and the SonUisel 11 or 11a, \ .-; ..-.

After attaching the dielectric oc.hlch t 12 or I2a over, the surface of the bowl 11 or 11a as described above is then the electric heating element film 12 or 13a on the Dielectric layer glued on. The heating element film is made by using a small amount of the organic binder stuck in the same solvent as the glue. To the

909893 / $ 110

BATH ORIGINAL

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Example are filler gaps on silicone-impregnated paper of the desired size on the dielectric layer 12 below Using a solution of polyisobutylene in toluene (about 10 wt. -56) as an adhesive. The movie will then be in serpentine pieces of surface, as shown in Figure 3, cut. To use electrical endpoints to connect the H iron linen t-Fi Ims 13 with an electrical energy source * u can create a pair of contact endpoints I5 and l6 integrated be formed with the heating element film, such as with a Film 13a of Figures 3 and 4. The upper lihtagrlinden are End points in the cooking appliance 10 of FIG. 2 have not been shown; end points such as 15 and 16 are made of a larger metal rich Ground than the remainder of the heating element film 13a. the End points are formed by placing a Apply a small amount of paste of the usual Unaofyttn Metal!

Where
applies to the surface area lit to form the endpoints.

Moisten the paste with solutions and apply pressure are sufficient to ensure an initial contact.

With the Dielektriicum layer, the previously _t on the cooking device has been applied as described above, and the duroh the binder on the dielectric Sohicht adhered heating element is now ready for the film to make it permanently to the dielectric layer (and the Koohgerät) by Burn to tie. The firing takes place in two stages. During the first stage, the binder is depolymerized, leaving behind the unsintered Pritte material and silver or silver oxide as a residue. This is quickly achieved by firing the above workpieces up to about 600 ° C for 15 minutes. A second stage immediately follows, with the specially used porcelain glaze, eg 800 ° C, being burned for 3 minutes during the maturation process. Prolonged heating at higher temperatures can lead to stronger flow of the glaze and should therefore generally be avoided. The burning occurs for a time sufficient to cause the olasur to ripen, including recrystallization, which is normally or even up to e ^ nera

909886/1101 ·

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certain Qrad occur at a lower temperature level can ·

During the second firing stage, when no binding agent is present, the heating element that is not lying flat may tend to drip or chip. It has been found that such undesirable effects can be conveniently counteracted by adding a small amount (1 - 10 %) of a low-temperature oil such as a blelboroellicate Ola lake in fine heights in the polymeric solute adhesive Combination used. This low-temperature glass preferably melts below ψ the temperature at which the polymer decomposes completely

is, for example, at 300 ° to 500 ⁰ C. The small amount given from the melt to Heiselernent-Plim without the silver ranges, so that the latter flieset to adhere. The silver is embedded in an essentially non-flowing matrix.

After firing, the metal-relieved end points 15 and 16 (FIG. 3) are somewhat thicker than the heating element film 13a. For example, if a heating element made up of 55 % porcelain frit material and 35 % silver oxide is used, endpoints 15 and 16 are attached using a film of equal amounts of frit material and silver oxide After firing, the heating element film 13 * », which was originally 0.6 mm thick, has shrunk to a thickness of about 0.10 to 0.15 µm; however, it is thicker than the end-point surfaces 15 and 16. Leads (such as leads 17a and 18a, which are connected to a power cable 19a of Figure k ) are connected to the end points 15 and by being soldered directly to the metal-rich end points and Ij. (like the leads 17 and 18, which are attached to the power cable 19 of FIG.

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layer lh are embedded, as shown in Figure 2. The leads 17 and 18 are tied directly to the strings 22 and 2} in a satisfactory manner,

Metal cooking utensils can be made from a thin metal with high heat loss and low heat capacity will. 0.15 cro thick mild steel is preferred because it is too Any desired structure can be formed and has a weight of 1.25 g per cm and a heat capacity of 0.14 cal / -

2
cm degrees. With light steel of this type, only a small amount of thermal energy is stored in the metal. Most of the heat goes directly into the food that is in the cooking appliance. Cooking and baking times can be reduced and the amount of heat that goes into the food can be more precisely regulated by regulating the current applied to the heating element film.

- patent claims -

909886/1108

Claims (7)

-13- M 2655 Patten tanapartlche ; Cooking appliance, characterized by a metal bowl (11, 11a), a glass-like porcelain dielectric layer (12, 12a), which sits on the surface of the bowl (11, 11a) in a defined area where the dielectric layer (12, 12a) from Bleiboroalllkat and tiny ^ uarz -Kris ta Ilen assembled, the crystals "ilt the lead borosilicate and each" melted Bind, and by a heating film (13, 13 '), you to the dielectric layer (12, 12a ), whereby this film (13-13a) is composed of a depolynerizable organic binder, of porcelain glaze material and finely divided conductive metal parts . 2. Kochger St according to claim 1, characterized in that the lead borosilicate and the minty quartz crystals were made from a mass of 40 to 75 ow.-jf blel borosilicate frit material and 25 to 60 ow.-ji made quartz crystals, the crystal "The said frit material from walking out of the" defined surface area 909886 / 11Ot bad 1957873 - 19 - M 2655 if the frit material is at melting temperatures this frit material merges into glass. 3. Cooking device according to one of the preceding claims, characterized characterized in that the heat capacity of the metal soleplate (11, lla) is less than 0.14 cal / cm .Orad. 4. Cooking device according to one of the preceding claims, characterized in that the Ponellan glaze frit material Partial size from less than 1 micron to 100 microns in Has diameter. 5. Cooking appliance according to one of the preceding claims, characterized in that the average diameter of the Porcelain glaze-FrI tte-Te Hohen 5 - to 10 times larger than is the average diameter of the conductive metal particles. 6. Cooking device according to one of the preceding claims, characterized in that the conductive Me tall particles Silver oxide with particle sizes from about 0.5 to 2.0 microns, the depolymerizable organic binder made of polyisobutylene and the porcelain glaze frit material from one recrystallizing. Titanium oxide containing PrI tte material consists. 7. Method for applying a glass-like Porsellan floorboard trikua sole (12, 12s) on the surface of a Meta11 cooking bowl (11, 11a) and binding of a heating element film <3D ,. 13a) to this dielectric layer (12, 12a), thereby characterized in that one prepares an aqueous mixture of silver bromide silicate material and quartz crystals, where the crystals range in weight from 25 move up to 60 wt. # of the frit material; nian this aqueous mixture on one on the surface of said Bowl (11, 11a) applies the base coat applied; 909 886/11 06 bad originac 1917875 - 20 - M 2-555 allowing the mixture to dry; the mixture burns at a temperature of 733 ° C in order to anchor the lead borosilicate frit material in the molten state and to leave a substantial amount of said quartz crystal He undissolved so that the viscosity of the lead borosilicate frit material can be controlled when it is anchored in the molten state and to bind the crystals to one another and to the lead borosilicate; the mixture is allowed to cool to room temperature; and a heating element in the form of a film (13, 13a) of recrystallizing porcelain glaze frit material in proportions of 85 to 50 % frit material and 15 to 50 % silver oxide binds to the dielectric layer (12, 12a). 3. The method according to claim 7 *, characterized in that bonding the hot element film (13 # 13a) to the dielectric layer (12, 12a) by using an adhesive made of a depolymerizable organic binder in one Solvent therefor, the 1 to 10 wt .- # of a low melting point Contains lead borosilicate olaaes, increases, is. 9 · Method according to one of the preceding claims, characterized in characterized in that one electrical end points (15, 16) by applying a never ta .lireich film over the parts des Heize learn t-Fi Ina (12a), where the electrical endpoints (15, 16) are intended to create. Dr.Pa./Br. BATH 909886/1106