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
  • H05B3/84—Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields
• • 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
  • H05B2203/016—Heaters using particular connecting means

Definitions

• the invention relates to a screen-printed electrical network for heated glazing, in particular for a rear window of a motor vehicle. More specifically, the invention relates to a glazing unit fitted with all of its conductive strips, that is to say strips forming strictly speaking the heating network and collector strips intended to be connected by welding to the supplied current leads. by the vehicle's current source.
• the first heating glazings thus produced included very conductive resistance bands, of a particularly high metallic silver content, with a view to a high heating capacity; therefore, the electrical power dissipated by the heating network was also very high.
• high dissipated powers are not well suited to small-displacement motor vehicles whose electrical reserve power is relatively low. This is all the more so since motor vehicles are today fitted with a whole series of electrical equipment which means that the maximum power capable of being dissipated at a given time is often less than the theoretical capacity required for simultaneous operation of all electrical equipment in the vehicle. Therefore, there is an increasing demand for heating glazing dissipating lower powers which - unless reducing the size of the heating circuit - requires the use of electrically conductive compositions having relatively lower silver contents. Concretely, while in recent years the heating networks were made from pasta with a silver content of around 75% or more, the market today is moving towards products made with pasta with a silver content is at least 71%.
• the current industrial practice is to deposit at the places provided for welding a pellet made of a paste with a high silver content, this second deposition being carried out for example by screen printing or with a brush and covering a surface of in the range of 1-4 cm2.
• the object of the present invention is to provide a more satisfactory solution to this technical problem of connection to the vehicle power source of screen-printed networks with low silver content.
• a heating glazing comprising a glass sheet provided on one of its faces with resistance bands formed of an electrically conductive composition resulting from the baking of a suspension in an organic binder of metallic silver and a low-melting frit and collector strips formed of the same electroconductive composition, windows according to the invention being closed by pellets made of an electroconductive composition having a greater silver content than that of the forming composition the resistance bands and the collector bands and having a dimension slightly greater than that of the windows so as to form overlap zones, the current supply terminals being welded to said pellets.
• the glazing according to the invention is thus presented with collecting strips with "holes” and pellets the silver content of which is most adequate for perfect welding of the current supply terminals.
• the window in the collecting strip allows the pellet to be directly in contact with the substrate and not superimposed as before.
• the substrate here is either glass or an enamelled layer previously deposited on the glass and used for example to mask the adhesive used during the installation of the glazing. In all cases, the connection between the substrate and the pellet is ensured by the frit so that there is no risk of the pellets peeling off.
• Such glazing can for example be obtained simply by modifying the screen screen used for the deposition of the heating network so as to provide windows which are subsequently covered by the deposited patches, either by a new screen pass or simply with a brush.
• the silver content of the composition forming the bands of the heating network is less than or equal to 71%, while for the pellets a silver content greater than 75% or even 80% is provided, which is very favorable. weld quality, the small size of the pellets allowing the use of rich pastes without resulting in a significant increase in the cost of glazing.
• An important point of the invention is, as indicated above, the direct bonding on the substrate of the patch, so that the overlap zones between the pellets and the collector strips are fixed over time with respect to the surface of the sheet of film. glass. It can certainly happen as with glazing according to the art that the pellet made of a paste with a high silver content does not adhere correctly to the collecting strip at the level of the overlap zone, but the pellet being anchored to the substrate the overlap area is always well presented, so that generally conduction is ensured by the simple fact of the close proximity of the two layers.
• the patch is placed under the collecting strip at the level of the overlap zone.
• the collector strip has its low silver content offset by a higher sinter content. During baking, the collector strip will therefore diffuse very easily towards the glass of which it is very close due to its composition. On the other hand, this diffusion is less for the pastille depleted in frit. Tests have shown that a paste with a silver content of 75% thus diffuses half as much as a paste with a content of 71%. Under these conditions, if the collecting strip covers the pellet, its tendency to diffusing towards the glass will lead to the formation of an interpenetration layer having an average silver content, which guarantees perfect conduction, while leaving the pellet available to weld current leads.
• the frame used has windows of adequate size in places already fitted with a pad.

Landscapes

• Surface Heating Bodies (AREA)
• Glass Compositions (AREA)
• Photovoltaic Devices (AREA)
• Resistance Heating (AREA)
• Conductive Materials (AREA)
• Joining Of Glass To Other Materials (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=9399306

Family Applications (1)

Country Status (4)

Family Cites Families (3)

• 1990
  • 1990-08-01 FR FR9009813A patent/FR2665605B1/fr not_active Expired - Fee Related
• 1991
  • 1991-07-25 DE DE1991608481 patent/DE69108481T2/de not_active Expired - Fee Related
  • 1991-07-25 EP EP19910402074 patent/EP0473473B1/fr not_active Expired - Lifetime
  • 1991-07-25 ES ES91402074T patent/ES2071255T3/es not_active Expired - Lifetime

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