JPH04229984A - Heater-equipped glass board - Google Patents

Abstract

PURPOSE: To control the heating of a warped glass plate by partly applying a dark enameled coating having high thermal absorbing ability to a bright colored concentration band, and by changing this enameled pattern. CONSTITUTION: A black enameled coating 8 is provided around the periphery of a glass plate 1 to form a thin heater net band 9, consisting of a frit containing silver, in a central portion 2. The enameled coating 8 and the heater net band 9 are formed and burnt by a screen method. A concentration band 10 is provided to control glass heating of side parts 3 and 4, a dark enameled coating having high thermal absorbing ability is partly applied to the concentration band 10, and consequently, a continuous black band 11 is provided so that bright white lines appear on the concentration band 10. In this manner, the heating of the glass plate 1 can be controlled to facilitate its warping.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to shaped glass panes, particularly of the type for car rear windows, provided with a screen process on which wire networks for de-icing and defogging are printed. More particularly, the invention relates to a glass plate which has a relatively significant curvature along its edges parallel to the concentration zone in which all the heating wire networks are concentrated and connected to the current leads.

0002

BACKGROUND OF THE INVENTION Many cars today are equipped with heated rear windows. According to FR 1 464 586, such a glass plate is obtained by providing on the surface of the glass plate a continuous narrow resistance band with a conductive composition. These resistance bands are printed flat on the glass plate before warping, using a screen process.
Thereby, sintering of the conductive composite occurs during the heating process of warping and strengthening the glass sheet. The conductive composite is formed by a pasty suspension of metallic silver and an organic combination of frit, a low melting glass. The mesh-shaped resistive band is relatively thin so as not to obstruct the visibility through the glass plate, and is connected to a wider and therefore better conductive concentrated band located near the edge of the glass plate. be done. These concentration bands are formed from the same composition as the resistance bands and are provided in the same way and preferably at the same time as the resistance bands. Current leads are then soldered to these concentrated zones.

[0003] Attachment to the vehicle by gluing presupposes an opaque surrounding band covering the adhesive from the outside, and in order to protect it against solar radiation or simply for aesthetic reasons, usually a glass plate. It has a black enamelled frame. This is obtained by a screen process that prints a pasty precipitate relatively similar to a silver paste, but in this process the silver is replaced by a suitable color. Thus, before its warping, the glass plate undergoes at least two screening steps of the printing operation, namely the provision of a layer of the frame and the corresponding heating net after drying, as well as, for example, the sleeving of the current leads. A possible third screen step may be added to locally increase the thickness of the heater mesh and, as a result, the soldering area for adjustment of its conductivity. receive.

The glass sheet may then be pressed in a warping/strengthening device, where the glass sheet is heated to a warping temperature and shaped in a warping station. It is not intended to describe said molding methods in detail here, since a large number of methods already exist and are well known to those skilled in the art. However, the most difficult shape to obtain, at least when respecting the most stringent optical quality criteria, is one with a surface with a very small radius of bending at the fold line located at the edge of the glass plate. One thing is pointed out. However, in the case of car rear windows, it is necessary that these shapes be accurate. Furthermore, the need for suitable optical quality is of great concern and priority for the warping process, in which the central part of the glass pane through which the driver sees is located between the two warping molds. Not pressured. Thus, in many cases, only the periphery of the glass plate is perfected according to the preformed mold, leaving some inaccurate contour outside of that periphery.

[0005] Generally, these slight changes in external shape are
Although this does not pose a problem, it is still a disadvantage in the folded edge portions that constitute the engaging portion of the glass pane of the vehicle body. Defects in the bends can then result in certain ineffectiveness of the seal, which has a tendency to open. In severe cases, these defects can make it impossible to install the rear window, which cannot be installed exactly in the desired position. These warping defects thus make it impossible to slide the glass plate in the direction of said position (in the case of a glass plate partially covering the body).

It is known that the profile of a glass plate depends very closely on the temperature curve of the glass leaving the furnace, and that the rate of deformation of the glass increases as it becomes hotter. At the temperatures involved here, differences of a small degree are sufficient to produce bowing defects of a factor of 10 of a few millimeters, ie they are clearly negated here.

Different measures have been proposed for controlling the heating curve of the glass pane of a heating furnace as precisely as possible. However, these means, for example in the form of burners that follow the glass plate as it advances through the furnace, result in more complex equipment and
Many settings are necessary and in many cases the results obtained are not always completely satisfactory with regard to the reproducibility of the shapes obtained.

[0008]

[Problems to be Solved by the Invention and Means for Solving the Problems] The inventor of the present invention has developed a new solution to this problem, paying attention to the fact that the severe part is the place where most of the concentration zones are concentrated. provide. These concentrated bands are white or whitish and, as a result, absorb heat better than transparent glass and, as a result, heat to a higher extent than enamelled black bands. tends to reflect heat.

[0009] In this way, in this difficult part,
There are both reflective and absorbing bands for heat. The invention provides very precise control of the heating of the glass plate in this critical area by covering the reflective band, ie the white concentration band, with a colored layer. This layer is preferably constituted by a fresh enamel coating provided by a screen step of the third or, if appropriate, fourth printing operation.

The essential feature regarding this colored layer or coating is that it is of a different color to the concentrated zone and, as a result, has a different heat reflection coefficient than the concentrated zone. Generally, the coating is black. If the concentration band is placed directly on the glass, this color choice is forced to replace the enamelled black frame-like band, the purpose of which is clearly to obtain a band with a matching shade. It is.

[0011] As in the above-mentioned situation, the covering of the concentration band is partial, at least the soldered part of the sleeve being excluded. Removing this constraint, the coated area must be distributed as a function of the temperature curve corresponding to the expected shape of the glass. To work in special cases, it is possible to have alternating black or white bands of successive varying widths, thus a suitable distribution to actually try different screens, and variations in outline. Obtained by observing the possibilities of Furthermore, it is clear that multiple screens correspond to a given temperature curve and are ultimately selected to function, on the basis of their aesthetic characteristics, if they can be provided by a screen process. be done.

It is finally pointed out that the selection of the screen depends not only on the shape given to the glass plate, but also on its shading, dark glass having different heating properties than clear glass.

The invention will be described in more detail below with reference to non-limiting examples and the accompanying drawings, in which: FIG.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a highly schematic representation of a rear window of a car. The rear window 1 is constituted by a glass plate with a thickness of 3.2 mm, for example, the central part 2 of which is slightly bent, the side parts 3, 4 of which are considerably bent about the axes 5, 6, and As shown by 7, it has a predetermined curved portion.

The entire periphery of the glass plate is provided with a black enamel coating 8 forming a frame. This can be a continuous or discontinuous covering, for example formed from a succession of points with varying distances, approaching the central part.

[0016] In order to de-fog and de-ice the central part 2, a heating screen is provided, which is formed from thin conductive strips 9 made of frits with silver, all of which are connected to two parallel edges. It is led to a wide concentration zone 10 arranged along the line. These silver-bearing bands are white in color. A soldered current lead sleeve is attached to the concentration zone.

Enamel coating 8 and heater mesh strips 9,1
Both are essentially formed from a suspension of a combination of low melting point glasses or frits. They must be applied by a screening process and then baked. Tempering occurs in a heating furnace for glass sheets before warping. In order to very precisely control the heating of the glass in the side parts 3, 4, and with the aim of obtaining a more precise profile in a given mold, including a certain distance from the edge of the glass pane, the invention provides a concentrated zone 10. It is suggested that the sleeve be dark colored, while minimally protecting the parts of the sleeve suitable for soldering.

FIG. 2 illustrates a concentrated zone covered by a continuous black band 11 so that a white line appears.

This darkening is effected by providing a new black enamel coating, which covers the focal zone. Because the covering cladding is not exposed to solar radiation (the heating screen is present on the inner surface of the rear window, so that the covering topcoat is present on the back side of the cladding 8), for the cladding 8 or otherwise, there are no complicated compositions. The same composition can be used so that .

[0020] This overcoat is provided in such a way as to allow the partial appearance of concentrated bands and to constitute alternating dark and light areas, the said areas depending on the shape of the glass required after warping. distributed to obtain optimal heating.

In the embodiment proposed in FIG. 2, the colored coating is arranged to form alternating black or white lines, which vary in length as a function of this part of the glass plate. Other patterns, such as grid patterns, dots, circles, divided circles, etc., can be tried by uniformly or non-uniformly distributed while taking into account the shape of the glass plate and finally the aesthetic appearance. Obviously it's possible.

[0022] It should therefore be noted that the prescribed tests with respect to the pattern are such that the white parts are colder and are therefore suitable for forming parts that are relatively flat, while the black parts are hotter and are therefore suitable for forming parts that are considerably deformed. is required for each type of new glass plate. It is further noted that the pattern preferably differs as a function of whether the glass plate is made of tinted glass or not. Once the pattern is selected, there is preferably a recurve that results in a very well controlled heating curve, which is a very limited method to accurately provide by a screen process.

[Brief explanation of the drawing]

1 is a view of a rear window of a car which is significantly bowed in the area where the concentration band is installed; FIG.

FIG. 2 is an enlarged view of a concentrated zone partially covered by a colored band.

[Explanation of symbols]

1...Glass plate 8... Enamel coating 9...Resistance band 10... Concentrated zone

Claims (7)

[Claims] 1. A resistive band (9) formed from a conductive composite resulting from calcination of a suspension of an organic combination of metallic silver and a low melting point frit, and a resistive band (9) formed from a conductive composite of the same type. A shaped heated glass pane comprising a curved glass pane provided on one surface thereof with a concentrating zone (10) formed, said concentrating zone (10) forming a concentrating zone (10); (10) A shaped heated glass plate, characterized in that it is partially covered with a colored coating having a heat reflectance less than that of (10). 2. A heated glass plate according to claim 1, wherein the colored coating is an enamel coating. 3. A glass plate with a heater according to claim 1, wherein the enamel coating is black. 4. Glass plate with heater according to claim 1, characterized in that the concentration zone (10) is provided on the enamel part (8) of the glass plate. 5. The colored coating is provided according to a band or part of a band such that the glass plate has continuous black and white alternating bands or parts of a band. The glass plate with a heater according to any one of 4 to 4. 6. The colored coating covers concentrated bands so as to form a uniform or non-uniform pattern of grids, alternating lines, dots, circles and divided circles. A glass plate with a heater according to claim 5. 7. A heated glass plate according to claim 4, characterized in that the colored coating is applied according to a pattern that varies as a function of the shade of the glass.