EP0035968A1 - Apparatus for forming, on a glass-sheet raised to a high temperature, a plurality of resistive tracks - Google Patents

Abstract

Heating and defrosting glazing comprising alternating conductive and non-conductive areas of electricity. The conductive pads are transparent when hot and arranged so that, during defrosting, they alone provide sufficient overall visibility through the glazing, the nonconductive zones being still opaque. The overall surface ratio between the conductive surfaces and the non-conductive surfaces is from 1/8 to 1/2.

Description

Technical field of the invention

The present invention relates to a glazing heating by Joule effect, a method for its manufacture and a device for the implementation thereof. Such glazing, the heating of which is ensured by the passage of an electric current through a conductor, makes it possible to remedy the lack of visibility caused by icing and fogging of the windows of vehicles traveling in cold weather. It can however be used in other fields, in particular in the building industry. It comprises on at least one of its faces a succession of areas (B) non-conductive of electricity alternating with areas (A), made conductive by the deposition by CVD (chemical vapor deposition) of a layer of Sn0 ₂ , in contact with a heating current source, the areas (A) and (B) being, under normal conditions, both transparent.

It is known that the usual heating glazings, in particular those used for the rear window of automobiles, comprise a network of electrically conductive wires or ribbons incorporated into the glass or applied to the surface thereof, this network releasing sufficient heat, when it is connected to the terminals of the vehicle battery, to melt the frost covering said window and thus restore to it, after a certain time, its normal transparency. Of course, this defrosting action manifests itself, firstly in the immediate vicinity of the conductive zone, the intermediate zones remaining still opaque for a certain time after the application of the current. As these conductive zones are themselves generally opaque (this is particularly the case when they are made up of ribbons of metallic paint), such partial defrosting is insufficient, in a first tenps, to ensure a suitable overall vision through the glazing; in fact, the glazing will not offer a sufficient general vision until the defrosted areas have extended significantly on either side of the conductive strips.

Prior art

We have sought to remedy this drawback, either by considerably thinning and bringing the conductive zones very close to each other (case of a very tight network, embedded in the glass, of conductive wires with a thickness of the order of m), or by applying a transparent uniform conductive layer on the glass (case of the deposit, for example, of a conductive film of tin oxide a few m thick), these solutions then providing a practically homogeneous heating of the glazing and a uniform demisting or defrosting thereof. However, such a renede presents a serious defect linked to the fact that, at equal powers, the global rise in temperature of a glazing with uniform conductive layer takes place much more slowly than that of the privileged zones located in the immediate vicinity of the conductive strips. conventional heated glazing. As a result, although glazing with a homogeneous conductive layer is uniformly defrosted, it only becomes sufficiently transparent for effective vision after a relatively long period of tensioning. This being so, a standard type of glazing heating subjected to the same conditions provides, by comparison, more quickly alternation ("zebra" appearance) of defrosted areas co-cidant with the conductive areas and of areas still frozen; however, as we have already said, in order to be able to see clearly through this type of glazing during defrosting, it is necessary to wait until the defrosted areas have spread enough and overflow on either side of the heating tape .

In view of the fact that it is hardly possible, in the automobile sector, to considerably increase the electrical power consumed and, by that, the speed of defrosting (the powers allowed for defrosting a rear window are of the order of 50 to 250 W), it has been imagined to overcome the aforementioned drawbacks of concentrating the heating on certain portions, transparent, of the anti-fog glazing, these portions, once clarified, providing a plurality of transparent patterns, the assembly of which provides sufficient useful visibility through this partially defrosted glazing.

Thus, patent FR No. 2,075,352 describes a heated glazing comprising three transparent electroconductive areas alternating with non-conductive areas (see page 2, lines 22-30 and fig. 1). Although it is not specifically indicated in this reference that the transparency of the conductive areas alone gives sufficient vision through the glazing, this seems fairly obvious from the arrangement of these areas in FIG. 1 of the drawing.

With regard to the manufacture of transparent conductive pads, the above reference mentions the technique of depositing bismuth oxide coated with gold by evaporation under vacuum.

Patent FR No. 1,116,234 describes the deposition, by spraying, of a layer of SnO ₂ on a heated glass sheet so as to constitute thereon a transparent film which conducts electricity (see pl, col. 2 lines 20-26). This application, illustrated on p.4, col.l, second paragraph and in fig. 3 is done by means of guns projecting horizontally a spraying solution against the glass sheet oriented vertically and perpendicularly to the sprayed jets and moving laterally in the projection area of these, the operation repeating, by back and forth comes, until the desired thickness is obtained.

In addition, it is indicated on p.5, col.l, lines 16-24, that the ends of the windshield (formed by the glass sheet) do not have any deposit, this having been partially removed by "ef- facade ".

A third reference, USP Patent No. 2,833,902, relates to the deposition of layers of SnO ₂ on glass plates by spraying with solution of organic tin compounds. This process is illustrated in fig. 4 where we see a set of four spray nozzles projecting a solution of tin compound on a heated substrate moving opposite these nozzles. However, it should be noted that, according to the drawing in FIG. 3 of this same patent, the traces of projection of the two superposed rows of nozzles overlap each other (this is obviously necessary for obtaining a homogeneous layer over the entire surface of the plate) which cannot in no way suitable for depositing conductive strips as desired to do in the invention.

A fourth reference, patent FR No. 1,165,645, concerns the deposition of transparent conductive layers the transmission of which does not exceed 72% (see p.4, Example 4). These layers are obtained by depositing transparent metallic films on transparent supports, these films possibly comprising gold, silver, copper, iron, nickel or other metals.

USP Patent No. 3,475,588 relates to de-icing glazing comprising a succession of contiguous heating zones, each of these zones being able to be heated according to an independent program. It is therefore not a case of glazing comprising alternating conductive and non-conductive areas as in the invention.

Patent FR 1,531,506 describes conductive glazing which can either include opaque resistances or include independent transparent conductive zones covering almost the entire surface of the glazing (see p.3, col. 2 above and fig. 5 ). This arrangement is not advantageous because it is too close to the solution where all the glazing is heated, solution whose drawbacks have been described above.

A seventh reference, US Pat. No. 2,564,677, describes the preparation of iridescent oxide conductive films on substrates by atanization of salt solution. It does not seem that this last reference contains data applicable to the manufacture of glazing of the type of that of the invention because of the lack of transparency of such iridescent deposits.

Description of the invention

The glazing of the invention also constitutes an interesting new solution to the problem posed above. This glazing is characterized in that the overall ratio of the total of the surfaces (A) / (B) is less than 1/2 and, in particular, between 1/8 and 1/2. Of course, the conductive pads (A) are, as in the prior art, in contact with a source of heating current, that is to say that one end of these is connected to one of the terminals of said source and the other end is connected to the other of these terminals. At the ambient temperature, the areas (A) and (B) are both transparent and, therefore, when it comes to thawing the glazing, overall surface ratio (A) / (B) is chosen in such a way that the lightening of the areas (A) alone allows sufficient general vision through the glazing. By sufficient general vision, we mean a vision such that the motorist can unambiguously detect the edges of the road and possible obstacles when he reverses or, in traffic, the presence of other vehicles behind him .

Preferred features of the invention

Preferably, the transparency (light transmission) of the areas (A) will not be less than 70-80% of the transparency of the areas (B).

Apart from the above criteria, the arrangement and the relative area of the zones (A) and (B) as a function of one another are chosen according to the needs and functional requirements to which the glazing of the invention will submitted. Most often, the zones (A) will consist of transparent conductive strips of constant width or not arranged parallel to one another on one or both sides of the glazing. In the latter case, the strips of one of the faces may be perpendicular to the strips of the other face, the assembly then constituting a heating grid. However, all kinds of other variants are possible, including that where a set of conductive strips is superimposed, on the same face, on another set, these being electrically separated from one another by a transparent insulating layer. In general, the surface ratio (A) / (B) will not exceed, around 1/2 if you really want to ensure rapid demisting or defrosting of the zones (A) without consuming too much current. Likewise, the shape of the pads (A) / (B) can be arbitrary provided that the assembly complies with the above requirements. The material of the conductive strips must therefore be both transparent and sufficiently conductive. As such material, tin oxide deposited by vapor phase reaction (CVD) is used. Indeed, the conductivity of the latter, particularly when deposited by CVD, is particularly suitable because it has a specific resistivity ((-) of the order of 1 ( ^3- 10 ^-4 Ω.cm approximately, this resistivity further decreases when the material heats up with the passage of an electric current. Thus, if we admit that, in the case of a homogeneous layer of SnO ₂ deposited by CVD of 0.5 to 1 μm thick, we have values of R _□ = 1 to 20Ω (which is indeed the case , according to the data of the applicant's Swiss patent application No. 7033/79) and that, on the other hand, a rear automobile window is 2 times wider than it is high, we will have, for such a window fitted of such a layer, a consumption under 12 volts of approximately 75 to 150 W, which corresponds well to the generally accepted power standards. Also, in one embodiment of the present invention, a heated glazing unit was produced comprising horizontal strips of Sn0 ₂ whose total surface constituted a quarter of the useful surface of the glazing and whose thickness was of the order of 2 to 5 µm. Such glazing dissipated an electrical power of the order of 50 to 100 W and, after icing, the areas covered with SnO ₂ regained their clarity much more quickly than the uniform witness glazing mentioned above. The areas covered with SnO ₂ had excellent transparency and in no way hampered visibility through the glazing because they were hardly noticeable. It is understood that it is possible, if desired, to produce a glazing whose surface ratio zone (A) / zone (B) is 1/8 or even less instead of 1/4 as above, the thickness of the SnO ₂ of the zones (A) then being from 4 to 8 μ (for the same energy dissipation). Glazing is then obtained, the heated zones of which defrost even more quickly than in the above-mentioned case. However, the ratio (A) / (B) cannot be reduced indefinitely because, then, the overall visibility effect provided by the thawed "zebra" obtained becomes insufficient (transparent patterns too fine in relation to the whole) and, moreover, if the layers of SnO ₂ are too thick, they lose their transparency which harms the general optical effect of the glazing under normal conditions. On the other hand, we can not increase the ratio (A) / (B) too much because, then, we get too close to the limit formed by the uniform layer whose defrosting is too slow. In general, it is preferable to have thicknesses of conductive SnO ₂ of at least 0.5 μm.

As we saw above, we can realize the glazing of the in vention using the usual CVD deposition techniques of SnO ₂ on glass; however, it is preferred to use a CVD technique inspired by the general method described in detail in the Swiss patent applications Nos. 1412/79 and 7033/79 of the applicant as well as in the German patent application DOS 2,123,244. As in the latter, the fundamental element of the coating device is a nozzle with concentric nozzles disposed in the immediate vicinity of the glass plate and projecting thereon, hot, gas streams of the reactants (diluted in a carrier gas) , the union of these reagents giving rise to the formation of SnO which is deposited on said plate. As the latter is movable transversely with respect to the gas jets, the deposit takes the form of a transparent ribbon adhering perfectly to the glass and of width determined by the dimensions of the nozzle and more particularly, by those of the suction enclosure. reacted gases surrounding said nozzle, the radius of dispersion on the glass plate of gases from this nozzle and, therefore, the width of said conductive pads produced by the reaction being precisely determined by the operation of this suction. Of course, the operating parameters (speed of flow of gas flows, concentration of reagents, etc.) also play a role concerning the dimensions and properties of the conductive zones). However, this CVD method hardly allows to exceed, in a single pass, a thickness of 0.8 to 1 µmm. Consequently, the zones of the glass plate intended to become conductive can be subjected to several successive passes of depositing the transparent conductive coating, the number of passes being essentially a function of the desired final thickness. In summary, the method for manufacturing the glazing of the invention according to which is made to arrive simultaneously on the plate, by means of a projection device, streams of reactive gases whose union generates the formation of a transparent conductive deposit , is characterized by the fact that, as soon as they are mixed in contact with the plate and formation of the transparent deposit thereon, the reacted gases are eliminated by sucking them up in a region immediately close to said projection device so that these gases do not spread uncontrollably on the plate and so as to keep the boundary between zones (A) and (B) clear and frank.

Description of the drawings

The accompanying drawing illustrates the process of the invention. Fig. 1 schematically represents a coating device by CVD ccm- taking a set of nozzles arranged so as to allow the production of a glazing according to the invention.

Fig. 2 schematically represents, partially in perspective, a glass plate provided with conductive zones (A).

The device shown comprises three nozzles 1, 2 and 3 (there could be more than three, of course), each of these comprising two concentric nozzles designated respectively by the letters a and b. The set of central nozzles marked a is connected by a general distribution piping 4 to a bubbler container 5 containing one of the reagents 6 allowing the formation of the transparent conductive layer; in this case it is SnCl ₄ , The nozzles b are connected by a distribution circuit 7 to a container 8 containing another reagent 9, in this case aqueous methanol. Furthermore, the device also comprises supply lines for carrier gas, respectively 10 and 11, immersed in the reactive liquids, this gas being intended to vaporize part of these, and evacuation chambers, respectively 12, 13 and 14, these enclosures (or pipes) collecting the by-products of the coating reaction, in this case HCl, and directing them towards an evacuation chimney 15. The present device is placed in the immediate vicinity of a glass plate 16 to be coated with SnO ₂ , this plate being supported by rollers 17 so as to ensure its movement perpendicular to the flow of the gas flows. As indicated in the drawing, the enclosures 12, 13 and 14 closely surround the nozzles 1, 2 and 3, respectively, and their size, as well as the suction depression which prevails therein, determine the field of dispersion on the plate 16 of gases from said nozzles and, thereby, the width of said conductive areas.

le SnO₂ se déposant sous forme de rubans sur la plaque 16 et le HCl formé étant entrainé de manière contrôlée, en compagnie du gaz porteur et des produits n'ayant pas réagi, dans la cheminée d'évacuation 15. En raison de la position concentrique des enceintes d'évacuation autour des buses, les gaz en contact avec la plaque 16 ne peuvent s'étaler librement sur la plaque au delà des limites inpo- sées par les dimensions de l'embouchure desdites enceintes qui les capture. Il résulte de cette disposition la formation de dépôts de SnO₂ dont l'empreinte est bien marquée et les bords nets et francs avec un minimum de diffusion sur les zones (B).The present device operates as follows: The glass sheet 16 is heated to a predetermined temperature, for example 500 at 600 ° C by means of an oven not shown in the drawing, and progressively conveyed, by the rollers 17, opposite the outlet of the nozzles 1, 2 and 3. Via the pipes 10 and 11, a predetermined flow is introduced , a carrier gas, for example an H _{2 /} N ₂ mixture, so that, by bubbling, it entrains, in the form of vapors, the reactants 6 and 9, these simultaneously opening out orifices a and b of each of the nozzles . These gases are projected onto the plate and, in contact with it, they react according to the reaction

SnO ₂ being deposited in the form of ribbons on the plate 16 and the HCl formed being entrained in a controlled manner, together with the carrier gas and the unreacted products, in the exhaust chimney 15. Due to the position concentric with the evacuation chambers around the nozzles, the gases in contact with the plate 16 cannot spread freely on the plate beyond the limits imposed by the dimensions of the mouth of the said chambers which captures them. The result of this arrangement is the formation of SnO ₂ deposits, the imprint of which is well marked and the edges sharp and clean with a minimum of diffusion over the areas (B).

In a single pass as described above, ribbons of SnO ₂ about 0.5 to 0.8 µm thick are formed. To produce the glazing according to the invention, several passes will be made, for example by ironing the plate, backward, then again forward, the number of times necessary for the conductive strips to acquire the thickness and conductivity chosen.

Of course, as a variant, it is possible to work continuously provided that there are several ranps of nozzles placed, one after the other, in the direction of movement of the plate to be coated. Such an arrangement, although not shown in the drawing, is easily confused, imagining two or more sets of devices such as that of the drawing placed side by side so that the deposit of each of the successive nozzles is superimposed on the deposit provided by the nozzle which precedes it. Or, in other words, an equivalent result is obtained by passing the plate four times opposite the drawing device or by passing it once opposite a battery of four similar units, the latter being arranged so that the trace of each unit is superimposed on that of the others.

Fig. 2 shows the glass plate 16 covered with 3 conductive strips (A) with clean edges of transparent conductive material 18 obtained according to the invention, these strips alternating with non-conductive areas (B). The thickness of this material, in practice a few µm, is greatly exaggerated in the drawing for obvious illustration reasons.

Possibility of industrial application

• On a construit un appareil similaire à celui représenté au dessin mais ccnportant 8 buses espacées de 5 cm par rangée et 5 rangée successives de buses. Les orifices des buses, toutes placées dans le même plan, avaient un diamètre de 5 mm, la tuyère intérieure (a) ayant 2 mm. Chacune des buses était entourée d'une conduite (ou enceinte) cylindrique d'aspiration coaxiale avec la buse et d'un diamètre de 12 mm. Ces conduites, dont l'embouchure inférieure dépassait l'orifice des buses d'environ 1 mm., aboutissaient, par leur extrémité opposée, à la cheminée d'évacuation laquelle était équipée de turbines d'aspiration conventionnelles (non représentées au dessin). L'alimentation des buses a été effectuée, également comme représenté schématiquement au dessin, au moyen des réactifs suivants :
  • a) SnC14 (tuyères intérieures (a); gaz porteur N_2/H₂ (60:40) au débit de 200 1/h; débit de SnCl₄ 2 ml/min.
  • b) solution aqueuse à 1 % de HF (tuyères extérieures b); gaz porteur N_2/H₂ (60:40), débit 300 1/h; débit du réactif 1 ml/min. les différents débits étaient réglés par des vannes placées sur les conduites d'amenées des gaz porteurs.
• On a procédé au dépôt du Sn0₂ sur une plaque de verre de 4 cm d'épaisseur, chauffée à 600°C et se déplaçant à 8,5 m/min. en regard et parallèlement au plane d'ouverture des buses. Les conditions de dépôt étaient les suivantes température des buses : 130°C; vitesse d'aspiration du HCl formé : 500 1/h.
• On a obtenu les résultats suivante : largeur des plages rectilignes 15 mm; épaisseur dépôt 2,5 µm, résistivité = 10^-3Ω.cm; résistance globale du vitrage R p = 0.4 Ω.
• On a ainsi obtenu un vitrage d'environ 30 cm de hauteur présentant 5 bandes conductrices de surface globale représentant environ 1/4 de la surface totale du verre.

The following example illustrates the invention in detail:

• An apparatus similar to that shown in the drawing was constructed, but comprising 8 nozzles spaced 5 cm apart per row and 5 successive rows of nozzles. The nozzle orifices, all placed in the same plane, had a diameter of 5 mm, the internal nozzle (a) having 2 mm. Each of the nozzles was surrounded by a cylindrical suction pipe (or enclosure) coaxial with the nozzle and with a diameter of 12 mm. These pipes, whose lower mouth protruded from the orifice of the nozzles by about 1 mm., Terminated, at their opposite end, at the evacuation chimney which was equipped with conventional suction turbines (not shown in the drawing). The nozzles were supplied, also as shown diagrammatically in the drawing, with the following reagents:
  • a) SnC14 (internal nozzles (a); carrier gas N _{2 /} H ₂ (60:40) at the flow rate of 200 1 / h; flow rate of SnCl ₄ 2 ml / min.
  • b) 1% HF aqueous solution (external nozzles b); carrier gas N _{2 /} H ₂ (60:40), flow rate 300 1 / h; reagent flow rate 1 ml / min. the different flow rates were regulated by valves placed on the supply gas supply pipes.
• We proceeded to deposit Sn0 ₂ on a glass plate 4 cm thick, heated to 600 ° C and moving at 8.5 m / min. opposite and parallel to the nozzle opening plane. The deposition conditions were as follows: nozzle temperature: 130 ° C .; suction speed of the HCl formed: 500 l / h.
• The following results were obtained: width of the rectilinear areas 15 mm; deposit thickness 2.5 µm, resistivity = 10 ^-3 Ω.cm; overall resistance of the glazing R p = 0.4 Ω.
• There was thus obtained a glazing of approximately 30 cm in height having 5 conductive strips of overall surface representing approximately 1/4 of the total surface of the glass.

• A -15°C, on a pulvérisé de l'eau sur la plaque, de manière à la recouvrir d'une couche de givre épaisse et absolument opaque. Puis on a relié les bandes de peinture conductrice latérales aux bornes d'une source de courant continu de 12 V et on a constaté qu'à -15°, les zones conductrices devenaient claires en approximativement 1 min, ce qui permettait d'avoir une vision générale suffisante à travers le vitrage.

After having applied a strip of conductive paint to its lateral ends, a plate of this glazing (60 × 30) was subjected to a standard icing and defrosting test as follows:

• At -15 ° C, water was sprayed onto the plate, so as to cover it with a layer of thick and absolutely opaque frost. Then we connected the lateral conductive paint strips to the terminals of a 12 V direct current source and we found that at -15 °, the conductive areas became clear in approximately 1 min, which allowed to have a sufficient general vision through the glazing.

It should also be noted that the glazing of the invention can also be produced from a glass plate covered, for example by the method described in application CH 1412/79, with a homogeneous layer of conductive SnO ₂ , a part of this layer then being eliminated, so as to provide an alternation of conductive and non-conductive areas. To partially eliminate the layer of SnO ₂ , the usual means can be used, in particular a felt polishing disc or roller provided with an abrasive paste, for example a diamond paste.

Claims (8)

1. Heating glass by Joule effect comprising on at least one of its faces a succession of areas (B) non-conductive of electricity alternating with areas (A) made conductive, by depositing, by CVD, a layer of SnO ₂ in contact with a heating current source, the areas (A) and (B) being, under normal conditions, both transparent, characterized in that the overall surface ratio (A) / (B) is between 1/8 and 1/2. 2. Glazing according to claim 1, characterized in that the transparency of the zones (A) is not less than 70% of those of the zones (B). 3. Glazing according to claim 4, characterized in that the zones (A) are parallel horizontal or vertical strips. 4. Glazing according to claim 1, characterized in that the SnO ₂ of the zones (A) has a resistivity of 10- ³ to 10 ^-4 Ω. cm and a thickness of 0.5 to 5u. 5. Method for manufacturing the glazing according to claim 1, according to which streams of reactive gases are made to arrive simultaneously on the plate, by means of a projection device, the union of which generates the formation of a transparent conductive deposit, characterized in that, as soon as they have been mixed in contact with the plate and formation of the transparent deposit thereon, the reacted gases are eliminated by sucking them into a region immediately close to said projection device so that these gases do not '' do not spread without control on the plate and so as to keep the boundary between zones (A) and (B) clear and frank. 6. Method according to claim 5, characterized by the fact that successive superimposed deposits are made by ironing the glazing several times opposite the device for projecting said gases. 7. The method as claimed in claim 5, characterized in that the plate is passed opposite several devices for projecting said gases, these devices being arranged successively, relative to the direction of movement of the plate, so that the traces of successive deposits provided by these devices overlap. 8. Devices for implementing the method according to claim 5, including, arranged side by side, a set of projection nozzles by each of which are made to arrive simultaneously on the plate of reactive gas streams whose union generates the formation of said transparent conductive deposit, characterized in that it comprises, surrounding each of the nozzles and in the immediate vicinity thereof, suction chambers for the reacted gases, the dimensions of these chambers determining the radius of dispersion over the plate of gases from said nozzles and, thereby, the width of said conductive pads.

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