Connecting device for a multilayer flat element equipped with electrical functional elements and flat element

Translation of description of equivalent WO 2004025995 A2

A connecting device for a flat element in several layers provided with electrical functional elements and flat element

The invention relates to a connecting device for a flat element in multiple layers that includes a first rigid pane provided with one or more electrical functional elements and a second rigid pane connected to the flat side of the first rigid pane with the functional elements, the latter having at least one cutout for making an electrical connection to the functional elements.

The invention also provides a flat element equipped with such a connecting device.

electrically conductive thin film systems is generally known that can be used as the heaters by applying an electrical voltage. There are many applications of this technique both in the automobile sector and the construction sector.

In general, these layer systems deposited on flat substrates, such as glass, comprise at least one metal layer, for example made of silver, as well as (for transparent multilayer systems) dielectric layers on both sides of the layer silver, and possibly also blocking layers of different materials, and among them also of the outer layers for enhancing the mechanical resilience of the layer structure. In many cases, it also uses the reflective properties of the infrared radiation layer systems as thermal insulation.

The establishment of a homogeneous current density in these multilayer systems used as heating layers is most problematic time. This is mainly to avoid places are locally overheated by high current densities, the so-called "hot spots" - hot spots. For this purpose and in many applications, it endows the heating layer of planar electrodes in strip form. They are for example made of thin metal ribbons deposited or good electrically conductive colors, which are printed and possibly cooked, and they help to introduce and evacuate the power on as wide a basis as possible. However, in most cases, these connections do not meet aesthetic optiques- requirements and must therefore be masked. As they are most often located on the edge of the substrate, in many applications, for example for vehicle windows, they can be made with a reduced implementation.

It is further known in such heating layers, how to act on the flow and the distribution of current through thin lines that divide the heating layer into individual sections or current paths electrically connected in parallel with each other, and whose ohmic resistances are all identical if possible.

In the German patent application 102 08 552.8 describes a plate with an electrically conductive coating element ( "heating layer") suitable to be connected directly to the usual mains voltages in the domestic field. It essentially consists of a composite multilayer structure comprising a first rigid pane with the heating layer deposited on it, and an adhesive and a second rigid glass layer. In the electrical connection zone of the heating layer, the second rigid pane is provided with a bore. In the region of this bore, two different polarity areas of the heating layer are located in close proximity. On each of these zones is provided an electrode applied to the heating layer and to which a current supply is connected by soldering. The current flow between the two connection terminals which belong to the same heating layer is guided in the manner already mentioned by dividing the heating layer by means of thin lines.

In DE-U1-201 07 908 describes a connecting device in which a coated glazing so as to be electrically conductive is provided with holding elements which are formed as clamping fittings which simultaneously serve as supports for contacts Power. Spring tongues integrated into the clamping fittings are applied electrically conductive manner on the coating of the glazing and pressed against the latter.

In another context, DE-Al-58 879 199 describes an insulating glazing unit provided with a composite glass pane with the adherent layer includes functional elements (solar cells). These electrical connecting conductors are each passed through a cutout in one of the panes of the composite and in the opposed rigid pane of insulating glass, the area of ​​the passage in the intermediate space between the insulating glass panes being surrounded by an annular spacer. Drivers may also be passed through a hollow journal of a point-like support which is used to fix the insulating glazing on an underlying structure.

In the field of fittings and fasteners composite glazing is known (DE-Al-39 08 983, DE-C2-43 25 024, DE-U1-87 01 693) the technique which comprises providing in the rigid pane cutouts in which the fastening elements can be inserted and fixed. These fasteners may have radial flange projections which extend into the adhesive layer of the composite and which, when the assembly is completed, engage behind the glazing. Their cuts may possibly have against an undercut. In the latter case, it was also described in the ankles against undercut for composite glass holders (DE-A1-38 11 249). The surface of the other side of these composite glazing remains whenever fully intact. The last mentioned sources are not concerned with electrical connection devices.

The object of the invention is to further improve a connecting device of the type indicated at the beginning and create a flat element which is so equipped.

According to the invention, this object is achieved in that a trim part is fixed in the cutout of the rigid pane by a projection whose edge is located in the plane between the two rigid panes and / or grip by the rear against an undercut of the cutout, and in that the liner is used against-support for fastening at least one connection piece electrically connected to the functional elements. Furthermore, it equips a flat member with electrical functional elements incorporated between two rigid plates and at least one connecting device according to the invention. The features of the independent claims and the dependent claims which are associated with the connecting device and one planar member provide advantageous developments of these objects. According to the invention, is placed in the cutout of one of the rigid panes a trim piece against which serves as abutment for the fixing of at least one connecting member electrically connected to the functional element. This trim piece has or forms a projection (radial) which is anchored in a form fit into the cutout.

As electrical functional elements, it is contemplated particularly heating elements, in particular heating layers, but also solar elements, sensors, which are each incorporated in a multilayer structure and to be brought into electrical contact with the outside. In the structure described here the coupling device or the trim piece, the function of elements that must eventually be connected is of secondary importance.

The functional elements may be the case arranged both on the rigid pane with the cutout on the rigid pane situated opposite thereof. is also possible to envisage embodiments in which the two panes are provided with electrical functional elements, for example electrodes for light emitting elements or solar cells, and are equipped with one or several connecting elements according to 'invention.

The edge of the cutout may hang from the rear of said protrusion the liner in the plane between the two rigid panes (plane of the adhesive layer). then fix the trim piece in the cutout before the manufacture of 1 'glazing assembly so that the protrusion can be incorporated into the adhesive layer. The thickness of the protrusion will be less than the thickness of the adhesive layer. The projection may also engage behind a back layer or a chamfer of the cutting located within the composite. This may be per se known manner achieved by a packing of several parts of which the individual parts are placed together in the actual cutting. As trim piece, however, also possible to use a dowel suitable against-cutting which forms said protrusion until it has been passed through cutting and has been clamped therein. Both alternatives can be advantageously installed after manufacture of the glazing assembly.

Particularly preferably, the trim piece can be used as a base for a collection point of the set of electrical interface functions of one planar member.

It then forms the basis of the actual electrical connecting contacts which are preferably configured as spring contacts. For the purposes mainly provided in a flat heating element whose operating voltages are relatively high, they must transfer a small current (AC); Also, the heating elements used in buildings are generally exposed to any vibration. So, do not expect to corrosion problems in other areas of use (construction vehicles) may impact damage from contact by high transfer resistances. In addition, if necessary, the contact area can be hermetically sealed so that moisture and dirt can not penetrate.

If necessary, the electrical contacts with the functional elements or their electrodes may however, also be made by soldering or only be protected in charge. Are known soldering techniques to melt safely these without direct contact welding locations with the heat source (induction welding or laser welding), and can be used even through the coated glass without destroying the coating .

The liner can be the basis for a connecting plug by which to electrically connect a connecting conductor of the functional elements. But it is clear that one can also provide a fixed connection conductor that is made out of a terminal box attached to the liner and which optionally has a plug at its end.

In another preferred variant, at least one switching element for switching on and off of the functional elements is provided in the region of the liner. In use as "flat heating element", the switching member may, in another advantageous embodiment, be controlled by at least one temperature sensor which detects the actual temperature of the heating layer in the connection area. As in this area of ​​the local electric power supply, the higher current densities may appear, there will at least one temperature sensor.

These temperature sensors can also be realized even as current limiters (e.g. cold conductors whose electrical / ohmic resistance increases when the temperature increases), thereby removing said switching member if an appropriate characteristic line is provided . Optionally, it can still provide a electrical protection that electrically protects the functional element.

In yet another advantageous embodiment, the liner may also form the basis of an evaluation device or receiving control signals by which a functional element / surface heating element may be individually requested by a remote control and be connected and disconnected. In the case of heating, these control signals are generated for example by means of room thermostats and temperature sensors. They can be transmitted by special conductors or by the supply conductors already provided as bus drivers. In the latter case, encoded control pulses are superimposed on the supply voltage or of the network and may be electronically filtered in the connecting device to the panel heating element concerned. Preferably, the control signals are however transmitted wirelessly by radio, infrared, etc., and in the region of the connecting device will be provided a receiver and an appropriate decoder in addition to the switching or control devices connected downstream.

In a complementary manner, the liner can be used as a basis for a manually adjustable temperature limiter which allows with a priority over the internal sensor may be provided temperature to set a maximum electrical power consumed and therefore the maximum effective temperature flat heating element below the predetermined absolute maximum temperature factory of the flat heating element.

In a particularly preferred embodiment, it will miniaturize as much as possible all necessary components (for example in the form of a microchip or microprocessor) and bring together in a housing or junction box which can be fixed with a reduced implementation on said trim piece. For binding, may be provided screws. However, it could also provide a snap-on connection (releasably) 1 if necessary sealing of the contact area can thus be obtained. Optionally, one could even consider a bonded connection between the liner and the connection box.

Simultaneously securing said connection box, one can also connect the electrical contacts (spring) to the functional elements. This has the advantage on the one hand not to exceed a predefined test pressure contacts, and secondly that, if released and any subsequent removal of the connection box in a maintenance order or repair, also disable the functional elements by disconnecting the current or electrically.

All the connecting device of the active elements may, optionally after appropriate adaptation of the voltage level, be electrically powered by an optionally applied operating voltage such to the functional elements. However, it could feed autonomously using batteries that will be placed in the connection box.

In the connection area, it is also possible with low implementation of the operating instructions for the check that the functional elements are connected, activated or ready for operation ( "stand by" - pending). In the case of a transparent flat member, these displays can be light signals which light passes through the flat element. It is obvious then they will not be covered by opaque or similar masks, or that appropriate observation windows are provided in such a mask.

In all the differences of the connection device described herein with respect to localized fastening elements usually used for plates (glass), it is also conceivable to use a connection point which has the characteristics described here also as mounting points for the planar member when the fixing member may be adapted to the conditions imposed on the electrically and its attachment to a substructure is possible. The latter can for example have the suspension devices or the flat elements that correspond to counter suitable carriers provided on the junction box which will be configured so as to have a suitable stability. Otherwise, the flat element is fixed in its mounting position using other appropriate means which commit such board (eg frames, retainer clips), or also be integrated with singing in a wall or a window facade.

The connecting device according to the invention may advantageously be installed practically anywhere on the surface of the flat member, either near the edge or in the central zone. It is obvious that, if necessary, many of these connecting devices can be provided on the same flat element, for example if several heating fields or solar cell modules capable of operating independently to be connected.

When placing the device for connecting a flat heating element, the requirement of a current density as uniform as possible in the heating layer to supply remains an important parameter, which may cause some restrictions on the choice of location of the connecting device.

Other details and advantages of the subject of the invention emerge from the drawing of exemplary embodiments of a connecting device for a flat heating element and their detailed description that follows.

In simplified and not to 1 scale representations:

1 shows an overall perspective view of a flat heating element with a connecting device according to the invention;

2 shows a view of the connection area with a trim insert for fixing the connecting device;

3 shows a sectional view of a first embodiment of the coupling device, along the line III-III of Figure 1;

4 shows a sectional view, corresponding to that of Figure 3, a second embodiment of the connecting device according to the invention; and

Figure 5 shows another sectional view corresponding to Figure 3, a third embodiment of the connecting device according to the invention.

According to Figure 1, a flat heating element 1 is configured as a glazing assembly with a first rigid pane 2, an intermediate layer 3 and a second rigid pane 4. The first rigid pane 2 is preferably a thermally prestressed glazing which is provided on its surface facing the intermediate layer 3 of a heating layer 5 configured as an electrically conductive coating. The heating layer 5 is made of a composition and / or a layer sequence which is suitable for operation as a heating flat layer and which can be sufficiently thermally loaded for biasing the glass. appropriate layers of systems have been described many times in the prior art, so it should not go into further detail. They can be manufactured with a high transmission of visible light and therefore so as to be transparent.

Appropriate provisions ensure that said coating 5 is passive to the periphery, along the flat heating element 1 edge, that is to say that there is no contact electrically conductive to the outer surface or front or the risk of corrosive attack by the outside of the layered material. For example, it may be provided in the covering 5, at a small distance from the outer edge of the flat heating element 1, a continuous peripheral parting line which fulfills both tasks. Alternatively, it may also, in known manner, subsequently completely release the material in layers or remove a narrow peripheral band along the edge of the flat heating element 1. In any case, is created with the adhesive synthetic material thermoplastic which forms the intermediate layer 3 (for example polyvinyl butyral (PVB) or ethylene vinyl acetate (VA)) a hermetic closure of the edge gap. It is understood that the material of the intermediate layer should be selected so as to be compatible with the material of the coating 5.

In Figure 1, we can see the essential components of the power supply of the heating layer 5 at first namely two planar electrodes 6 in the form of tape which are arranged on both sides of a line of separation 7 which isolates one vis-a-vis each other the two poles of the heating layer 5. the course of the current path between the two electrodes is predetermined by the structural lines formed in the heating layer and spring without problem design. A junction box 8 with a connecting cable 9 (which is shown only in part) is fixed at the location of electrical contact between the heating layer 5 and the pair of electrodes 6 of the second rigid pane . Particularly advantageously, all devices and electrical interfaces are collected locally at a location of the flat heating element 1.

In contrast to the representation of Figure 1, the electrodes can of course have other shapes than those of a ribbon (e.g., semicircle). In addition, one can start structural lines in the area of ​​the heating layer which is covered by the electrodes, so that one electrode is put into electrical contact with several current paths electrically connected in parallel. Such a configuration or structure of the heating layer adjacent to its connection area can be especially necessary when one power supply could not be possible to close to the edge, unlike what is shown.

In Figure 2, one can see the area Electrical connections of the flat heating element in a plan view in which it failed to represent the junction box. The window 4 can also be made of glass (optionally prestressed) or synthetic material, has a bore 11 in which a liner 12 shaped sleeve is fixedly inserted. Its outer perimeter is suitable for the most accurate way possible to the diameter or the perimeter of the bore 11. For a protruding collar overflowing 13, configured here as annular shoulder, the liner 12 engages behind the edge of the bore 11 in the plane of the intermediate layer 3. the free inner space of the liner 12 releases visibly the heating layer 5, the two electrodes 6 and the parting line 7. the surfaces are represented by fields gray rectangular on which the electrical connection contacts can to be placed.

The liner 12 may include shaped units that secure and preventing the connecting device from turning. In this embodiment, they are nozzles formed in the wall of its bore and provided with bores in which screws can be screwed. Unlike the representation, these shaped elements may be arranged unsymmetrically to allow insertion in the correct position other components.

3 shows with further detail of an exemplary electrical connector structure according to the invention in section, with identical parts being provided with another reference numeral as in Figures 1 and 2. It can be seen the multilayer structure of the flat heating element. Shows a part of the thickness of the rigid pane 2, and a double chain line which passes through the rigid pane 4 also indicates that its thickness has been shown shortened. It is obvious that these two rigid panes can be significantly thicker than the intermediate layer 3. In the region of the electrodes 6 and the junction box 8 (which is here shown only partially), their material has been removed to allow barrier-free access to the electrodes 6. This material removal must be sized before connecting the two rigid panes by melting the intermediate layer 3 so that the adhesive material can advance to the electrodes.

In this representation, the diameter of the bore 11 has been shown smaller compared to the thickness of the window 4; it is understood that the bore is sized to a width sufficient for the type provided in each case connecting device.

An optical masking of the connection region is not necessary for its operation, and only performs an aesthetic mission. In the mounted state, the pane 2 and therefore the side of the flat heating element facing away from the connecting device, forms its visible side. It is only by way of example that there are provided in the region of the connecting electrodes 6 of an opaque layer 10 between the heating layer 5 and the glass surface to mask this vis-a-vis the area of 'outside. If necessary, it is obviously also achieve the same effect with other means, for example by dyeing the rigid pane 2 in the mass application of a decoration on its outer surface and / or design of the heating layer itself as a mirror, for example by omitting one antireflective layer on its side near the substrate.

Furthermore, the electrodes themselves can also be used as decorative elements in giving an optically attractive appearance. Then we can do without the opaque layer 10.

As can already see in Figure 2, the liner 12 in the form of sleeve is fixed in the bore 11 of the second rigid pane 4. Its axial length substantially corresponds to the thickness of the rigid pane 4 (a few millimeters) and it enters again in the plane of the intermediate layer 3. the radial projection 13 which collar projects outwardly engages behind the edge of the bore 11, so that the liner 12 there is held in the form of correspondence and can not be extracted.

As was noted above, this trim piece should be inserted into the bore 11 before connecting the two rigid panes 2 and 4. Only after fusion of the thermoplastic intermediate layer 3 that it is fixed permanently. In the drawing, it can be seen that the projection 13 is still superimposed on the intermediate layer material.

The liner 12 forms the base of the junction box 8. Two vertical lines denote a screwed chain link between the two parties. A support block 14 is fixed by the connection box 8 within the bore of the liner 12, from which two spring contacts 15 that extend to the electrodes 6, which are based on an electrically conducting manner thereof. A temperature sensor 16 is symbolically indicated also maintained at 1 using the contact block 14 and the liner 12 in contact with the coated surface of the rigid pane 2. It is used to detect the actual temperature in the contact zone electrodes 6. The support block 14 is inserted in the correct position, possibly forced by appropriate shaped elements, in the liner 12 so that the spring contacts 15 come into contact with the electrode every time provided, and then immobilized. The support block may form a first fixed unit with the junction box 8 and be fixed at the same time that the latter in the liner 12.

Although in the intended use of a flat heating element 1, the spring 15 contacts meet the requirements of a safe and sustainable electrical connection, if required, they could be welded, particularly through appropriate pre-tinning , the necessary heat can be provided without contact, for example through the glass coated 2.

Switching symbols of a switch 17 and a transistor 18 are electrical or electronic equipment of the support block 14 or the junction box 8 and may each represent a plurality of corresponding elements. Other control and switching tasks are also allocated to this region of the connecting device in addition to the supply of electrical supply voltage to the electrodes 6 by the connecting cables 9.

A switching element must evaluate the values ​​measured by the temperature sensor 16 and possibly at least temporarily disconnect the power supply to the heating layer if the actual temperature must exceed an acceptable threshold. However, one can also provide a switching element that ensures protection against overtemperature and limiting in a known way the electric power consumed to acceptable values.

At least one switch that may have a electronic or electromechanical configuration manages the power supply to the heating layer. This switch can be basically connected manually and locally and be controlled by sensors, for example the temperature sensor 16, or by a remote control device. As already indicated, the latter can form a part of an automatic control of the temperature of a room (air-conditioning, etc.) but may also be optionally and basically controlled by hand.

If the control signals are transmitted wirelessly, a suitable receiver and a decoder and other switching means (for example amplifiers) must be provided in the connection box 8 or in the support block 14. If the control signals are transmitted via conductors, provide appropriate evaluation bodies for this purpose, especially if control signals are transmitted by the network connecting conductors, anyway present (cable 9), and must be filtered on site.

Not shown here of display elements of the operating state of the flat heating element 1. In a preferred variant, they can be configured in the form of light signals (light emitting diodes) and for example be arranged in the region of the separating line 7 between the spring contacts 15 and next to the temperature sensor 16 so as to be visible from the outside of the rigid pane 2. They are also electrically fed by one intermediary of support block 14 and controlled by said switching elements 17, 18.

After fabrication and verification operation of the connection device, if necessary, can still make the transition between the glass surface and the connection box 8 sealed by a seal 19. In contrast to what is shown, can of course also have this seal directly between the lower side of the junction box 8 and the surface of the glass.

4 shows, in a sectional view corresponding to that of Figure 3, a variant of a trim piece which is used here in a bore against undercut 11 'of the second rigid pane 4. If 1' there is shown the same components as in Figure 2, they receive the same reference numerals and are not explained. The liner is constructed in two parts, with a pin to undercut against 12D and a screw 12S socket. We already know such socket undercut in many applications on glass. Conducting bores 11 'against undercut or recessed in the glass panes is also technically mature.

12D ankle against undercut can be inserted from the outside into the bore 11 'after completion of the assembly. then is screwed to the screw sleeve 12S can be made of metal or a high strength plastic. Vertical lines along its outer harbor indicate its self-tapping external thread. When screwing is established the deformation given to the ankle against undercut 12D in a projection 13 'which projects radially collar. We see that this protrusion fills the chamfer against the undercut of the bore 11 'in geometric correspondence until its axial extraction becomes impossible. Similarly, the screw sleeve 12S is fixed radially and axially in the bore by engagement of its external thread in the ankle.

The possible penetration of the ankle to undercut 12D in the plane of the intermediate layer can not lead to excessive local stresses that could effect a local delamination or even breaking a window. In case of doubt, it will remove the material of the intermediate layer in case it is not sufficiently deformable in the region of the bore 11 'for the distance indicated, and therefore substantially to its edge, so that the peg can expand freely in the plane of the intermediate layer.

Screw socket itself can also be screwed to a predetermined depth as not to come into contact with the electrodes in the bottom of the bore 11 'or damaging them or the heating layer 5. It can not more to come touch the contact springs 15.

Instead of a fixing bearing glass, in the present application should not be expected that high forces act, so that the ankle of the clamping force should not be particularly high. However, it may be necessary to also perform window 4 prestressed glass, and in this case the bore 11 'must be formed before prestressing.

In a particularly advantageous variant, the junction box 8 and the socket screw 12S may be combined into a fixed entity. We could then use the housing of the junction box as a lever to tighten the socket screws by hand, the underside of the terminal box which is placed on the upper side of the glass 4 at the edge of the bore 11 'then forming a depth stop. In this unit, the carrier block may be fixed in the correct position with the contact springs and optionally the temperature sensor.

While in both Figures 3 and 4, the liner is substantially adjoins song with the main surface of the rigid pane 4, the junction box protrudes slightly above that surface. As this side of the flat heating element 1 is mostly not facing the viewer / user in the assembled state, is optionally located in front of a wall or is integrated in the latter, the visibility of connecting device onto the mask (or optionally on the opaque electrodes configured as decorative elements) is limited in part, and secondly risk by tampering or inadvertent connection device are excluded in practice. If there is provided a handle for one actuation of a control member of the connecting device, the latter will be available naturally preferably in easily accessible locations, for example near the edge of the flat heating element.

Although reference to Figure 4, it has spoken a peg against undercut for the application "bore against undercut" in the second rigid pane 4, when needed, particularly if the thickness of window 4 is quite limited, for example less than 5 mm may be used for this purpose as part GARNITU re other suitable components, of the type already shown and similar to that of the liner 12 of Figure 2.

The embodiment of Figure 5 combines a connecting device 1 according to the invention with a plate member, wherein the functional elements electrical connecting are located on the second rigid pane 4 provided with the bore 11. In contrast to the variants described above, it is provided here no direct contact between the spring contacts 15 and the electrode plates 6 of the heating layer 5. the projection 13 of the liner 12 serves to maintain the contrary contacting the connecting bridges 20 with the electrode plates 6, after the liner 12 has been inserted and fixed in the bore 11 of the rigid pane 4. as the liner can be clamped with the connection box 8 and thus the projection 13 is drawn with a preload against the flat electrodes 6, this point of contact is not particularly critical. The connecting bridges of surfaces coming into contact with the planar electrodes may be made rough or provided with spikes to allow a slight penetration of the connecting bridges in the planar electrodes. One can here also, however, as already mentioned above, to realize a welding heat input, with a pre-tinning of the connecting bridges and / or planar electrodes.

The ends of the connecting bridges 20 opposite to the planar electrodes 6 penetrate into the inner space of the piece of liner 12. They form at this place, in an equivalent manner to the flat electrodes of the preceding applications, bearing faces for the contacts spring 15 so that after assembly, these are electrically connected reliably via a respective connection bridge 20 to the respective six planar electrodes themselves.

The connecting bridges 20 are preferably fixedly incorporated into the liner 12 in order to configure as simply as possible the mounting of the connecting device. This can e.g. be obtained by molding the connecting bridges 20 (thin sheet strips) with the plastic material of the liner 12 at its formatting.

the dividing line again recognizes 7 between the two poles of the heating layer 5 and the opaque layer 10, on which the heating layer is deposited in each case in the contact region. In addition, there are still here provides another opaque layer 10 'on the plane side of the rigid pane 2 lying inside in the composite, which optically covers the contact region and which can be carried out further in the form of decorative element. Optionally it is possible, as required, also omit one or two opaque layers, because they are not significant for the functioning of the coupling device or the plate element.

While the intermediate adhesive layer 3 is continuous in the contact region in this illustration, it may also need to be provided also in this embodiment of a cutting manner similar to Figures 3 and 4.

In Figure 5, no temperature sensor has been illustrated, but it will be understood that an appropriate detection element for detecting the actual temperature in the connecting region may also be provided in this embodiment. It would be possible for example to perform an additional temperature sensor similarly to the connecting bridges 20 illustrated herein and the contacting with the heating layer or an electrode plate.

When said connection means is used for electrical functional elements of other types, for example for solar cell layers thin or impact sensors or precipitation, as we have indicated at the beginning, its basic structure is not changed with respect to that of the embodiments shown here. By departing drawings, one can possibly predict only a single contact or a plurality of contacts in each cut.