FR2737075A1 - Electrically heated window for motor vehicle - has metal layer deposited in horizontal bands on glass to form heating resistance, with resistance having narrower width in preferred visibility region - Google Patents

Abstract

The window has the resistance heating element (4) supported by the glass (1). The electric elements are connected to an electrical supply by connector strips (3) at the edges of the window. The electrical resistances lie horizontally in bands forming a horizontal grid across the window. The resistances are placed on the window surface by deposition of a metal onto the glass. They are then covered by a protective coating. The width of the resistances in the preferred visibility region is less than at the edges of the window to make them less intrusive in the field of vision.

Description

AUTOMOTIVE WINDOWS WITH ELECTRIC HEATING
The invention relates to automotive glazing with electric heating of the type comprising a glass support carrying the electrically conductive and current supply strips.

The publication FR-A-2509947 describes a glazing in which the current supply strips are covered by an electrically insulating protective layer under which the lateral sections of the conductors are widened.

Such glazing allows the protection of the current supply strips and a bonding of the glazing on a frame carried by a panel of the bodywork.

It is known to have electric conductors on the surface of the glazing and to provide an area in which their resistance is lower, in order to concentrate the heating on said area and to allow acceptable rear vision using the interior rearview mirror system. to the passenger compartment.

The publication FR-A-2075R52 describes a glazing on which the electric heating is reinforced in order to create differential fields of vision.

When the electric conductors are located in the field of vision, it seems unsightly that a change in thickness is visible.

The invention aims to remedy the aforementioned drawback.

According to the invention the electrically conductive, respectively located in the preferential field of vision zone, are deposited on a screen formed by an insulating enamel of uniform width substantially greater than that of said conductors.

The glazing thus produced may be equipped with conductors as weak as possible and the differences in width of the electric conductors are masked by the insulating enamel coating.

On the glazing thus the network of electroconductive can be carried out by deposition on the insulating enamel of a conductive paste.

The deposition is carried out in a conventional manner by a screen printing process by means of a screen whose structure includes cutouts for the deposition of resistant bands.

The heating glazing thus obtained can also in known manner be reinforced by a second layer of protective enamel covering the various heating elements.

Other characteristics and advantages of the glazing will appear on reading the description with reference to the appended drawing in which - FIG. 1 is a schematic representation of the interior face of a
automotive glazing heating with preferential field of vision.

- Figure 2 is a view on a larger scale of part of an electrically conductive.

- Figure 3 is a schematic representation of the outer face of the
glazing shown in Figure 1.

- Figure 4 is an enlarged sectional view of part of the glazing
shown in Figures 1 and 3.

Reference will first be made to FIGS. 1 and 2 of the drawing in which the reference 1 designates the rear glazing (laminated glass support) of a motor vehicle.

The glazing has a laminated border structure 10 consisting of a colored ceramic layer 2 and a conductive layer.

According to Figure 1 which shows the inner face of the glazing facing the passenger compartment of the vehicle, the colored ceramic layer is formed on the outer edge of the inner face of the glazing.

Omnibus conductors 3 are formed on each of the two sides of the colored layer 2.

Several thin electric conductors 4 are formed between the two omnibus conductors 3.

Examples of embodiment of such ceramic layers and conductors are part of the state of the art as described in the publication FR-A-2618387.

The glazing according to FIG. 1 has a zone 11 of preferential field of vision. In this zone 11, the electric conductors 4 have a width of close to 0.5 mm and are advantageously applied by a screen printing process to the screen and can, after firing, be reinforced by electroplating.

To obtain the desired result, care should be taken that in zone 11 the electroconductive such as 4 has a resistance of 0.02 Q at 0.05 2 / cm and a width of 0.5 mm.

On the other hand, in the border area 12 of the glazing and near the area 11 of the preferential field, the electric conductors 4 have a wider width (b) close to 1.2 mm and a greater resistance of 0.02 μl to 0.07 q / cm.

In order to mask the conductors 4 between the opposite border areas 12, these are arranged on screens formed by a non-conductive enamel 13 formed on the support 1.

As an example, the enamel is made up of a composition of N 60% glass sinter
15% lead
10% manganese
3% boron
5% titanium
5% bismuth
1% of other elements printed on the glazing in the manner of ceramic layer 2.

A second protective enamel 14 covers all of the conductors 4 and the omnibus conductors 3.

Claims (2)

1) Electrically heated automobile glazing in which a support in  glass (1) carries electric conductors (4) distributed in areas of  preferential fields of vision (11) which have in the direction  horizontal electrical resistances as a function of said zones,  characterized by the fact that the electrically conductive (4) are arranged on  screens consisting of a first enamel (13) formed on the support  glass (1). 2) automotive glazing according to claim 1, characterized in that  that the electroresistors consist of a metallic deposit of  reduced width in the preferred field of vision area  (it) and covered by a second protective enamel (14).