Pane assembly having a heatable composite pane having a capacitive switching region

Abstract

A pane arrangement directed to a heatable composite pane having a capacitive switching region, including a substrate and a cover pane is disclosed. At least one intermediate layer is arranged between the substrate and the cover pane. A carrier film having an electrically conductive layer is arranged between the substrate and the intermediate layer or between the cover pane and the first intermediate layer. The electrically conductive layer forms a capacitive switching region having a contact region, a supply line region, and a connection region. The supply line region electrically connects the contact region to the connection region that can be electrically connected to a sensor electronics system. A heating wire and at least two busbars are arranged between the substrate and the cover pane, wherein one end of the heating wire is electrically connected to one of the busbars. A capacitive sensor electronics system is electrically connected to the connection region via a first input and to the heating wire or to the busbars via a second input.

Claims

1. A pane arrangement, comprising: a sensor electronics system, and a heatable composite pane having a capacitive switching region, including: a substrate and a cover pane, and a first intermediate layer arranged between the substrate and the cover pane, wherein a carrier film having an electrically conductive layer is arranged between the substrate and the first intermediate layer or between the cover pane and the first intermediate layer at least in sections, wherein a region of the electrically conductive layer forms the capacitive switching region, wherein the capacitive switching region has a contact region, a supply line region, and a connection region, wherein the supply line region electrically connects the contact region to the connection region and the connection region is electrically connectable to the sensor electronics system, wherein one or more heating wires and two or more busbars are arranged between the substrate and the cover pane, wherein one end of the one or more heating wires is electrically connected to a busbar of the two or more busbars, such that upon application of an electrical voltage to the two or more busbars, a heating current can flow through the one or more heating wires, thereby heating the one or more heating wires, wherein the sensor electronics system is electrically connected to the connection region via a first input and to the one or more heating wires or to the two or more busbars via a second input, and wherein the capacitive switching region in projection through the composite pane overlaps with a wire of the one or more heating wires.

2. The pane arrangement according to claim 1, wherein the second input of the sensor electronics system is connected to an electrical ground.

3. The pane arrangement according to claim 1, wherein the one or more heating wires and the two or more busbars are arranged between the first intermediate layer and the cover pane.

4. The pane arrangement according to claim 1, wherein a minimum distance of an edge of the carrier film from one side edge of the substrate or from one side edge of the cover pane is greater than or equal to 5 mm.

5. The pane arrangement according to claim 1, wherein a second intermediate layer is arranged between the substrate and the carrier film with the electrically conductive layer.

6. The pane arrangement according to claim 1, wherein the one or more heating wires includes a metal, and has an electrically insulating sheathing.

7. The pane arrangement according to claim 1, wherein the supply line region has a length of 1 cm to 70 cm and has a width of 0.5 mm to 10 mm.

8. The pane arrangement according to claim 1, wherein an area of the contact region is from 1 cm.sup.2 to 200 cm.sup.2, and has a rectangular, square, trapezoidal, triangular, circular, elliptical, or drop- shaped form or is formed with rounded corners.

9. The pane arrangement according to claim 1, wherein the first intermediate layer and/or a second intermediate layer, arranged between the substrate and the carrier film with the electrically conductive layer, is transparent, contains or is made of polyvinyl butyral (PVB), and/or has a relative permittivity .sub.r,2/3 of 2 to 4 and the carrier film is transparent, contains or is made of polyethylene terephthalate (PET), and/or has a relative permittivity .sub.r,5 of 2 to 4.

10. The pane arrangement according to claim 1, wherein the substrate and/or the cover pane contains glass, or polymers, and/or mixtures thereof.

11. The pane arrangement according to claim 1, wherein the electrically conductive layer is transparent and/or has a sheet resistance of 0.4 ohm/square to 200 ohm/square and/or contains silver (Ag), indium tin oxide (ITO), fluorine-doped tin oxide (SnO.sub.2:F), or aluminum doped zinc oxide (ZnO:AI).

12. The pane arrangement according to claim 1, wherein a sensitivity of the sensor electronics system is selected such that it outputs a switching signal upon contact of the contact region with a human finger on an outer surface of the substrate and outputs no switching signal or a different switching signal upon contact of the contact region on an outer surface of the cover pane.

13. The pane arrangement according to claim 1, wherein a sensitivity of the sensor electronics system is selected such that it outputs a switching signal upon contact of the contact region on an outer surface of the substrate and/or on an outer surface of the cover pane with a human finger and outputs no switching signal or a different switching signal upon contact of the supply line region on the outer surface of the substrate and/or on the outer surface of the cover pane.

14. A method for producing a capacitive composite pane, comprising: providing a first intermediate layer, a transparent electrically conductive later, a carrier film, two busbars, one or more heating wires, and a cover pane; cutting the first intermediate layer to size; applying the transparent, electrically conductive layer on a surface of one side of the carrier film by cathodic sputtering; applying the two busbars on a surface of the first intermediate layer; applying the one or more heating wires on the surface of the first intermediate layer such that the one or more heating wires is electrically connected to both of the two busbars; producing a stack sequence of the substrate, the first intermediate layer with the one or more heating wires and with the two busbars, the carrier film with the electrically conductive layer, and the cover pane; and laminating the stack sequence to form the capacitive composite pane.

15. A method of using a pane arrangement, comprising: attaching a pane arrangement according to claim 1 in means of transportation for travel on land, in air or on water.

16. The pane arrangement according to claim 1, wherein a minimum distance of an edge of the carrier film from one side edge of the substrate or from one side edge of the cover pane is greater than or equal to 15 mm.

17. The pane arrangement according to claim 1, wherein the supply line region has a length of 1 cm to 8 cm, a width of 0.5 mm to 2 mm, a shape of rectangle, a strip, or a line, and wherein the ratio of the length to the width of the supply line region is from 1:5 to 1:100.

18. The pane arrangement according to claim 1, wherein an area of the contact region is from 1 cm.sup.2 to 9 cm.sup.2, and/or has a rectangular, square, trapezoidal, triangular, circular, elliptical, or drop-shaped form or has a shape with rounded corners.

19. The pane arrangement according to claim 1, wherein the first intermediate layer and/or a second intermediate layer, arranged between the substrate and the carrier film with the electrically conductive layer, is transparent, contains or is made of polyvinyl butyral (PVB), and/or has a relative permittivity .sub.r,2/3 of 2.1 to 2.9 and the carrier film is transparent, contains or is made of polyethylene terephthalate (PET), and/or has a relative permittivity .sub.r,5 of 2.7 to 3.3.

Description

(1) In the following, the invention is explained in detail with reference to drawings and exemplary embodiments. The drawings are a schematic representation and not true to scale. The drawings in no way restrict the invention.

(2) They depict:

(3) FIG. 1A a plan view of an embodiment of a pane arrangement according to the invention with a composite pane according to the invention,

(4) FIG. 1B a cross-sectional representation along the section line A-A of FIG. 1A,

(5) FIG. 1C an enlarged representation of the carrier film according to the invention of FIG. 1A,

(6) FIG. 1D a cross-sectional representation along the section line B-B of FIG. 10,

(7) FIG. 2A a plan view of an alternative embodiment of a pane arrangement according to the invention with a composite pane according to the invention,

(8) FIG. 2B a cross-sectional representation along the section line A-A of FIG. 2A,

(9) FIG. 2C a cross-sectional representation of an alternative embodiment of a composite pane according to the invention along the section line A-A of FIG. 2A, and

(10) FIG. 2D a cross-sectional representation of an alternative embodiment of a composite pane according to the invention along the section line A-A of FIG. 2A, and

(11) FIG. 3 a cross-sectional representation of an improvement of a composite pane according to the invention along the section line A-A of FIG. 2A, and

(12) FIG. 4 a detailed flowchart of one embodiment of the method according to the invention.

(13) FIG. 1A depicts a plan view of an exemplary embodiment of a pane arrangement 101 according to the invention with a composite pane 100 according to the invention.

(14) FIG. 1B is a cross-sectional representation along the section line A-A of FIG. 1A. The composite pane 100 comprises here, for example, a substrate 1 and a cover pane 4, which are bonded to one another via a first intermediate layer 3 and a second intermediate layer 2. The composite pane 100 is, for example, a motor vehicle pane and, in particular, the windshield of a passenger car. The dimensions of the composite pane 100 are, for example, 0.9 m x 1.5 m. The substrate 1 is, for example, intended to be turned toward the interior in the installed position. In other words, the outer surface IV of the substrate 1 is accessible from the interior; whereas, in contrast, the outer surface I of the cover pane 4 points outward relative to the vehicle interior. The substrate 1 and cover pane 4 are made, for example, of soda lime glass. The thickness d1 of the substrate 1 is, for example, 1.6 mm and the thickness d4 of the cover pane 4 is 2.1 mm. Of course, the substrate 1 and cover pane 4 can have any thicknesses, and, for example, can also be implemented with the same thickness. The intermediate layers 2,3 are thermoplastic intermediate layers and are made of polyvinyl butyral (PVB). They have, in each case, a thickness d2/3 of, for example, 0.38 mm. A carrier film 5 with, for example, four capacitive switching regions 10 is arranged between the first intermediate layer 3 and the second intermediate layer 2 in the central, lower section of the composite pane 100.

(15) In the example depicted, eight heating wires 21, which run parallel to the bases of the trapezoidal composite pane 100, are, for example, arranged between the first intermediate layer 3 and the cover pane 4. The heating wires 21 are, in each case, connected at their ends to a busbar 22, the busbars 22 being in each case connected to a supply line 23. The heating wires 21 are thus connected to the busbars 22 in a parallel circuit such that upon application of an electrical voltage to the busbars 22 (via the supply lines 23), a heating current can flow through the heating wires 21. The heating current results in heating of the heating wires 21 due to development of Joule heat such that the composite pane 100 as a whole can be electrically heated.

(16) The heating wires 21 are made, for example, in each case of a 30-m-thick copper wire, which has an electrically insulating sheathing, black- or green-colored, for example. This sheathing has multiple advantages: the copper wire can be arranged depending on the requirements of the embodiment, and, for example, also cross over other electrically conductive structures without a short-circuit occurring. Moreover, the heating wire is protected against corrosion by the polymeric sheathing. Additionally, the reflection on the colored sheathing is lower than on the metallic copper inner conductor, such that the heating wire is visually less conspicuous.

(17) Each heating wire 21 is electrically contacted on its ends to, in each case, a busbar 22. The busbars 22 are implemented as strips of a copper foil, with a thickness of, for example, 100 m and a width of, for example, 7 mm. When a voltage is applied to the busbars 22, a current flows through the heating wires 21, creating the heating action. The voltage can be the customary motor vehicle on-board voltage of 14 V, or also a voltage of, for example, 42 V or 48 V.

(18) FIG. 10 depicts an enlarged representation of the carrier film 5 according to the invention of FIG. 1A, FIG. 1D depicts a corresponding cross-sectional representation along the section line B-B of FIG. 10.

(19) The carrier film 5 is, in this example, a transparent polyethylene terephthalate (PET) film with a thickness d.sub.5 of 0.05 mm. A transparent electrically conductive layer 6 is arranged on the carrier film 5. The electrically conductive layer 6 is a layer system that includes, for example, three electrically conductive silver layers that are separated from one another by dielectric layers.

(20) The electrically conductive layer 6 extends, for example, over one entire side of the carrier film 5. In the exemplary embodiment depicted, the electrically conductive layer 6 is arranged on that side of the carrier film 5 that faces the substrate 1. The carrier film 5 is set back by a distance of approx. 8 mm from the pane edge into the pane interior. This region is hermetically sealed by gluing the two intermediate layers 2,3 during lamination such that the electrically conductive layer 6 is protected against moisture from the surroundings of the composite pane 100 and, thus, against corrosion and damage. Alternatively, it would be possible to leave the carrier film 5 coating free in an edge region or to remove the electrically conductive layer 6 there.

(21) The electrically conductive layer 6 is divided by coating-free separation lines 7 into different regions electrically isolated from one another. In the example depicted in FIG. 1C, two capacitive switching regions 10 are electrically divided by a common surrounding region 15. Each switching region 10 includes a contact region 11, which is implemented nearly square and transitions into a strip-shaped supply line region 12. The width b.sub.B and the length l.sub.B of the contact region 11 is, in each case, for example, 40 mm. The width b.sub.Z of the supply line region 12 is, for example, 1 mm. The ratio of b.sub.Z:b.sub.B is thus approx. 1:40. The supply line region 12 is connected to a connection region 13. The connection region 13 has a square shape and an edge length b.sub.A of, for example, 12 mm, The length l.sub.Z of the supply line region is approx. 48 mm.

(22) The separation line 7 has a width t.sub.1 of, for example, only 100 m and is introduced into the electrically conductive layer 6, for example, by laser patterning. Separation lines 7 with such a low width are hardly perceptible optically and interfere only a little with vision through the composite pane 100, which, particularly for use in motor vehicles, is of special importance for driving safety and is also particularly aesthetic.

(23) The connection region 13 is electrically conductingly connected to a foil conductor 17 via an electrical line connection 20. A reliable electrically conducting connection is preferably obtained by means of an electrically conductive adhesive. The foil conductor 17 is made, for example, from a 50-m-thick copper foil and is, for example, insulated outside the connection region 13 with a polyimide layer. Thus, the foil conductor 17 can be guided out, without an electrical short-circuit, beyond the surrounding region 15 via the bottom edge of the composite pane 100. Of course, the electrical line connection of the connection region to the outside can also be guided outward via insulated wires or via a region in which the electrically conductive layer of the surrounding region is interrupted.

(24) Here, the foil conductor 17 is, for example, connected to a capacitive sensor electronics system 14 outside the composite pane 100. Moreover, the surrounding region 15 is also connected to the sensor electronics system 14 via another connection region 16. The sensor electronics system 14 is suited to precisely measure capacitance changes of the switching region 10 relative to the surrounding region 15 and to forward a switching signal, for example, to the CAN-Bus of a motor vehicle as a function of a threshold value. Any functions in the motor vehicle can be switched via the switching signal. For example, the electrical heating function of the composite pane 100 can be switched on or off by applying and switching off an electrical voltage to the heating circuit made up of busbars and heating wires.

(25) When the composite pane 100 is used, for example, as a windshield in a motor vehicle, the length of the supply line region 12 can be selected such that the driver of the vehicle or the front seat passenger can comfortably reach the contact region 11 of the switching region 10.

(26) In the exemplary embodiment depicted, the structure and tuning of the sensor electronics system 14 are coordinated such that when the outer pane surface IV of the substrate 1 is contacted via the contact region 11 of the capacitive switching region 10, a switching signal is triggered, whereas when the outer pane surface I of the cover pane 4 is contacted via the capacitive switching region 10, no switching signal is triggered. To this end, the thicknesses and the materials of the composite pane 100 according to the invention are selected according to the invention such that the surface capacitance c.sub.I between the contact region 11 and the outer surface IV of the substrate 1 is greater than the surface capacitance c.sub.A between the contact region 11 and the outer surface I of the cover pane 4.

(27) The surface capacitance c.sub.I or c.sub.A is, in the context of the present invention, defined as the capacitance of a plate capacitor of that region of the composite pane 100, which results from orthogonal projection of the contact region 11 between the contact region 11 and the outer surface IV of the substrate 1 or the outer surface I of the cover pane 4, with the resultant capacitance normalized over the area of the contact region.

(28) In the example depicted in detail in FIG. 1B, the surface capacitance c, between the contact region 11 and the outer surface IV of the substrate 2 results as the serial connection of the individual capacitances (1/c.sub.1+1/c.sub.2).sup.1, with the individual capacitance resulting at c.sub.i=.sub.0*.sub.r,i/d.sub.i. This corresponds to the capacitance C.sub.i of the respective individual layer with relative permittivity .sub.r,i and thickness d.sub.i, normalized over the area A of the contact region 11, i.e., c.sub.i=C.sub.i/A.

(29) Moreover. the surface capacitance c.sub.l , between the contact region 11 and the outer surface I of the cover pane 4 results as the serial connection of the individual capacitances (1/c.sub.3+1/c.sub.4+1/c.sub.5).sup.1.

(30) The relative permittivity of the substrate 1 and of the cover pane 4 are, here, for example, .sub.r,1.sub.r,4=7; the relative permittivity of the first intermediate layer 3 and the second intermediate layer 2 are, here, for example, .sub.r,2=.sub.r,3=2.6, and the relative permittivity of the carrier film 5 is, here, for example, .sub.r,5=3. This yields a ratio of the surface capacitances c.sub.l:c.sub.A at 1.2:1.

(31) Moreover, in this example, the area A of the contact region 11 and in particular its width b.sub.B is coordinated with the width b.sub.Z of the supply line region 12 such that a switching signal is output only when the outer surface IV of the substrate is contacted via the contact region 11 (i.e., in the region of the surface IV that results from orthogonal projection of the contact region 11 onto the surface IV) and not when the surface IV is contacted via the supply line region 12.

(32) As experiments of the inventors surprisingly showed, the presence of the heating wires between the contact region 11 of the electrically conductive layer 6 and the cover pane 4 further increases the selectivity, in other words, the sensitivity upon contact on the outer surface IV of the substrate 1 is further increased significantly compared to contacting the outer surface I of the cover pane 4. This was unexpected and surprising.

(33) FIG. 2A depicts a plan view of an alternative exemplary embodiment of a pane arrangement 101 according to the invention with a composite pane 100 according to the invention.

(34) FIG. 2B is a cross-sectional representation along the section line A-A of FIG. 2A. For simplification, the foil conductor 17 is not shown, Here, the composite pane 100 comprises, for example, a substrate 1 and a cover pane 4, which are bonded to one another via a first intermediate layer 3. The composite pane 100 is, for example, a pane and in particular the side pane of a passenger car. The dimensions of the composite pane 100 are, for example, 1.0 m0.6 m, wherein the front edge of the side pane is slanted in the region of the upper edge. The substrate 1 is, for example, intended to face the interior in the installed position. In other words, the outer surface IV of the substrate 1 is accessible from the interior, whereas, in contrast, the outer surface I of the cover pane 4 points outward. The substrate 1 and the cover pane 4 are made, for example, of soda lime glass. The thickness d.sub.1 of the substrate 1 is, for example, 2.1 mm; and the thickness d.sub.4 of the cover pane 4 is, for example, likewise 2.1 mm. The first intermediate layer 3 it is a thermoplastic intermediate layer and is made of polyvinyl butyral (PVB). It has a thickness d.sub.3 of 0.76 m.

(35) Eight heating wires 21 are, for example, embedded in the surface of the first intermediate layer 3 facing the cover pane 4. The heating wires 21 are made, for example, of copper and have a thickness of 30 m. Each heating wire 21 is electrically contacted on its ends with a busbar 22 in each case. The busbars 22 are implemented as strips of a copper foil, with a thickness of, for example, 100 m and a width of, for example, 7 mm. When a voltage is applied on the busbars 22, a current flows through the heating wires 21, creating the heating action. The voltage can be the customary motor vehicle on-board voltage of 14 V or also a voltage of, for example, 42 V or 48 V, In the exemplary embodiment depicted, the busbars 22 are connected to a voltage source 24, which provides a ground potential on one busbar 22 and a voltage of 14 V on the other busbar 22.

(36) In the central, lower section of the composite pane 100, four carrier films 5, each with a capacitive switching region 10, are arranged between the first intermediate layer 3 and the substrate 1. The carrier films 5 have on one end a drop-shaped configuration, which forms the contact region 11. The contact region 11 is electrically conductingly connected via a narrow region of the carrier film 5, the supply line region 12, to a square connection region 13. In this example, each carrier film 5 has a complete electrically conductive layer 6, which is not divided by separation lines or other isolations. In other words, here, the carrier films 5 have no surrounding region.

(37) The carrier film 5 is, in this example, a transparent polyethylene terephthalate (PET) film with a thickness d.sub.5 of 0.05 mm. The electrically conductive layer 6 is a layer system that contains, for example, three electrically conductive silver layers that are separated from one another by dielectric layers.

(38) Each switching region 10 includes a contact region 11, which is implemented approx. drop-shaped and transitions into a strip-shaped supply line region 12. The width b.sub.B and the length l.sub.B of the contact region 11 is, in each case, for example, 40 mm. The width b.sub.Z of the supply line region 12 is, for example, 1 mm. The ratio of b.sub.Z:b.sub.B is thus approx. 1:40. The supply line region 12 is connected to a connection region 13. The connection region 13 has a square shape with rounded corners and an edge length b.sub.A of, for example, 12 mm. The length l.sub.Z of the supply line region is approx. 48 mm.

(39) The electrically conductive layer 6 extends, for example, over the entire surface of one side of the carrier film 5. The carrier film 5 has a distance from the edge of, for example, 15 mm to the nearest side edge of the composite pane 100. This region is hermetically sealed by adhesive bonding of the first intermediate layer 3 to the substrate 1 during lamination such that the electrically conductive layer 6 is protected against moisture from the surroundings of the composite pane 100 and thus against corrosion and damage. In the exemplary embodiment depicted, the electrically conductive layer 6 is arranged on that side of the carrier film 5 that faces the substrate 1.

(40) The connection region 13 is electrically conductingly connected to a foil conductor 17 via an electrical line connection 20. A reliable electrically conducting connection is achieved preferably by an electrically conductive adhesive. The foil conductor 17 is made, for example, of a 50-m-thick copper foil and is, for example, isolated outside the connection region 13 with a polyimide layer. Thus, the foil conductor 17 can be routed out without electrical short-circuit beyond the surrounding region 15 via the lower edge of the composite pane 100. Of course, the electrical connection of the connection region 13 to the outside can also be guided outward via insulated wires or via a region in which the surrounding region 15 is interrupted.

(41) Here, the foil conductor 17 is connected, for example, outside the composite pane 100 to a capacitive sensor electronics system 14.

(42) As already mentioned, the carrier film 5 has, in this exemplary embodiment, no surrounding region; in other words, the electrically conductive layer 6 completely forms the contact region 11, the supply line region 12, and the connection region 13. In order to nevertheless enable a differential measurement of the capacitance, the sensor electronics system 14 is electrically conductingly connected to one of the supply lines 23 of the busbars 22. In this example, via the supply line of the busbar 22 that is connected to the vehicle ground (on the right, in FIG. 2A).

(43) The sensor electronics system 14 is suitable for precisely measuring capacitance changes of the switching region 10 compared to the heating circuit composed of heating wires 21 and busbars 22 and for forwarding a switching signal, for example, as a function of a threshold value, to the CAN-Bus of a vehicle. For this, it is particularly advantageous for the capacitive switching area 10 in projection through the composite pane 100, to overlap one of the heating wires 21.

(44) Any functions in the vehicle can be switched via the switching signal. For example, the power supply 24 of the heating circuit composed of heating wires 21 and busbars 22 can be selectively turned on or off or regulated, and the heating function of the composite pane 100 can thus be controlled.

(45) Alternatively or additionally, the composite pane 100 can have a suspended particle device (SPD). an electrochromic or other type of layer or film for controlling optical transparency, which can be changed in its optical transparency by the switching signal, here, for example, with four transparency levels, which can be selected in each case via the four capacitive switching regions 10. Of course, alternatively or additionally, other electrical functions, such as electrical lighting, moving of the composite pane 100, for example, opening or closing of a side window in a vehicle door, can be controlled. Alternatively or additionally, one or a plurality of capacitive switching areas 10 can form a keypad and coupled to an electronics system, can, for example, upon input of a specific key sequence, open or lock a vehicle door, switch an alarm system on, or perform complex controls.

(46) If the composite pane 100 is used, for example, as a roof panel in a vehicle, the length of the supply line region 12 can be selected such that the driver of the vehicle, the front seat passenger, or a passenger in the backseat can conveniently reach the contact region 11 of the switching region 10. Of course, for this, even multiple carrier films 5 can be arranged in the composite pane 100, for example, a carrier film 5 for each vehicle occupant.

(47) In the exemplary embodiment depicted, the structure and tuning of the sensor electronics system 14 are coordinated such that when the outer pane surface IV of the substrate 1 is contacted via the contact region 11 of the capacitive switching region 10, a switching signal is triggered, whereas when the outer pane surface I of the cover pane 4 is contacted via the capacitive switching region 10, no switching signal is triggered. This has the particular advantage that no switching signal can be triggered by intentional or unintended contacting of the composite pane 100 from outside the vehicle. Also, unintended triggering of a switching signal, for example, by rain or by a carwash is avoided. For this, the thicknesses in the materials of the composite pane 100 according to the invention are selected such that the surface capacitance c.sub.I between the contact region 11 and the outer surface IV of the substrate 1 is greater than the surface capacitance c.sub.A between the contact region 11 and the outer surface I of the cover pane 4. Furthermore, it is advantageous but not essential for the capacitive switching area 10 to be arranged nearer the substrate 1 than the heating circuit.

(48) The cross-sectional view depicted in FIG. 2C corresponds to a composite pane 100 according to that of FIG. 2B, wherein only the electrically conductive layer 6 is arranged on that side of the carrier film 5 that faces away from the substrate 1.

(49) The cross-sectional view depicted in FIG. 2D corresponds in its configuration to that of FIG. 2C, wherein the heating wires 21 and the busbars 22 are arranged not between the cover pane 4 and the first intermediate layer 3 but rather between the substrate 1 and the first intermediate layer 3, Here, the heating wires are arranged immediately adjacent the electrically conductive layer 6. In order to avoid electrical short circuits, the heating wires 21 are electrically isolated by a polymeric sheathing. As investigations of the inventor surprisingly showed, the function of the capacitive switching area is not substantially impaired by spatial proximity between electrically conductive layer 6 and heating wire 21. This result was unexpected and surprising for the person skilled in the art.

(50) In an advantageous embodiment, at least one heating wire 21 is implemented curved, wound, lengthened meanderingly, in a zigzag or otherwise, at least in one subregion of the projection of the electrically conductive layer 6. This has the particular advantage that, in this section of the heating wire 21, the composite pane 100 can be more strongly heated. Thus, the position of the capacitive switching region 10 and in particular of the contact region 11 can be deiced or cleared of condensation particularly quickly and the position of the capacitive switching region 10 is quickly and simply identifiable for the user. Moreover, the asymmetry of the capacitive switching sensitivity is reinforced by this embodiment.

(51) FIG. 3 depicts an improvement of a composite pane 100 according to the invention of FIG. 2B. In this example, additional shield wires 25 were placed between the carrier film 5 and the first intermediate layer 3, in a region that results from projection of the contact region 11 onto the first intermediate layer 3. By means of the shield wires 25, the asymmetry of the capacitive switching sensitivity is reinforced although the shield wires 25 need not be connected either to the heating circuit nor to the sensor electronics system 14. The shield wires 25 can consist of wire sections electrically isolated from one another or of one or a plurality of, for example, wound or meandering wires, Of course, the shield wires 25 can also be electrically connected on one side or both sides to the reference ground or to the heating wires 21.

(52) Of course, the shield wires 25 can also be positioned on the same level as the heating wires 21. For this, for example, the heating wires 21 can be arranged between the substrate 1 and the first intermediate layer 3, as is depicted, for example, in FIG. 2D. This is particularly advantageous and simple to realize from a production technology standpoint. FIG. 4 depicts a flowchart of an exemplary embodiment of the method according to the invention for producing a composite pane 100 with a capacitive switching region 10.

LIST OF REFERENCE CHARACTERS

(53) 1 substrate 2 second intermediate layer 3 first intermediate layer 4 cover pane 5 carrier film 6 electrically conductive layer 7 separation line 10 capacitive switching region 11 contact region 12 supply line region 13 connection region 14 capacitive sensor electronics system 15 surrounding region 16 further connection region 17 foil conductor 18 coating-free edge strip 20 electrical line connection 21 heating wire 22 busbar 23 supply line of the busbar 22 24 power supply 25 shield wire 100 composite pane 101 pane arrangement A area of the contact region 11 b.sub.A width of the connection region 13 b.sub.B width of the contact region 11 b.sub.z width of the supply line region 12 c.sub.I, c.sub.A, c.sub.1 . . . 5 surface capacitance C.sub.1 . . . 5 capacitance d.sub.1,d.sub.2,d.sub.3,d.sub.4,d.sub.5 thickness .sub.0 electric field constant

(54) .sub.r,1, .sub.r,2, .sub.r,3, .sub.r,4, .sub.r,5 relative permittivity l.sub.A length of the connection region 13 l.sub.B length of the contact region 11 l.sub.Z length of the supply line region 12 r distance from the edge t.sub.1 width of the separation line 7 A-A section line B-B section line I outer surface of the cover pane 4 IV outer surface of the substrate 1