Verification arrangement for the capacitive detection of a physical quantity on the inside and / or outside of a vehicle or building window or in its immediate vicinity

Description

[0001] The invention relates to a detection arrangement for the capacitive detection of a physical quantity on the inside and / or outside of a vehicle or building window or in its immediate vicinity.

[0002] In motor vehicles and buildings, the monitoring of environmental conditions and parameters is playing an increasingly important role in safe and efficient operation. Modern cars, as well as high-quality buildings, are therefore equipped with a multitude of sensors that detect relevant environmental conditions and parameters and deliver the current values ​​to processing and control units that manage the vehicle's or building's functions. This applies not only to motor vehicles but also, to some extent, to certain watercraft.

[0003] Certain sensors can be advantageously mounted on or in the windshield, or possibly also the rear window or a glass roof unit of a passenger car. Such arrangements have long been known for so-called rain sensors, which control the vehicle's windshield wiper functions. Within the general trend toward the largely complete prefabrication of vehicle components, there are developments aimed at integrating such sensors into a prefabricated glazing unit (such as the windshield or rear window) of a vehicle. Corresponding solutions are mentioned in the unpublished European patent application No. 17192877.3. Vehicle windshields with integrated or partially integrated sensors are also known from EP 2 121 308 B1 or CN 101 087 135 A.

[0004] Capacitive sensors, widely used especially as so-called "rain sensors" (or touch sensors), function by generating an electric field between two electrodes spaced apart on a substrate and influencing this field with the physical quantity being measured. However, the influence of this field is often significantly distorted by interference. In particular, the measurement signal of such sensors is highly dependent on the permittivity (dielectric conductivity) of the substrate, which in turn exhibits a marked temperature dependence. Consequently, one must either accept limited reliability of the sensor signals or implement complex additional measurement and processing equipment to compensate for the interference in parallel and / or after the fact. This, of course, increases the complexity of the corresponding detection setup and thus its costs.

[0005] EP 1686026 A1 shows a sensor arrangement with two capacitor electrodes on one side of an intermediate layer and a shielding electrode on the other side of the intermediate layer. DE 102008043610 A1 shows a disk with a sensor element formed by two capacitors and a shielding electrode connected to ground.

[0006] Starting from the state of the art, the object of the invention is to provide a correspondingly improved detection arrangement.

[0007] This problem is solved by a detection arrangement with the features of claim 1. Advantageous further developments of the inventive concept are the subject of the respective dependent claims.

[0008] In the context of the invention, a "glazing unit" in the general sense is understood to be a product that can be used to close window openings of a vehicle or building, either directly (frameless) or after insertion into a suitable frame. In modern motor vehicles, this will generally involve laminated glass panes, and in new buildings in mid- and northern latitudes, insulating glass units; however, the invention is not limited to these. Rather, it can also be used with simple single-pane glazing units or multi-pane glazing units with a special design, such as glazing units for armored vehicles or for explosion-proof rooms. The panes of the glazing unit do not necessarily have to be made of glass; at least a portion of them can also be made of a transparent plastic, such as polycarbonate.

[0009] In this context, a capacitive sensor is generally understood to be one whose function is based on the generation and detection of changes in an electric field caused by the relevant physical quantity, and where the detection result is influenced by the permittivity of the sensor's substrate. In a particularly important application in automotive engineering, this refers to a humidity or "rain" sensor; however, a capacitive sensor can also be used to detect other quantities in or on a vehicle or building.

[0010] The invention initially incorporates the concept of a deliberate departure from the usual practice of subsequently computationally computing for conductivity or temperature influences in the signals of a capacitive sensor. It further incorporates the concept of implementing a physical compensation directly at the sensor assembly. The invention also incorporates the concept of achieving this sensor-inherent compensation by means of an additional electrode and the creation of an additional electric field that penetrates the sensor substrate and is thus influenced by the permittivity of the substrate and its changes in the same way as the actual measurement signal.

[0011] The invention makes it possible to save considerable effort and costs associated with subsequent signal compensation in the detection setup, with minimal additional effort in the manufacturing of the sensor device. Furthermore, direct, sensor-inherent compensation is inherently superior to subsequent computational compensation and generally delivers more accurate results.

[0012] In a practically important embodiment of the invention, the glazing unit is designed as a laminated glass pane comprising a first and second glass pane and a polymer film bonded between them, wherein the first and second sensor sections are arranged on the inner surface of the first glass pane adjacent to the first surface of the polymer film, and the material property compensation electrode is arranged on the inner surface of the second glass pane adjacent to the second surface of the polymer film.

[0013] The polymer film is considered a property-critical component of a capacitive sensor mounted in a laminated glass pane, and in the proposed embodiment, the additional electrode is provided on the side facing away from the sensor. However, for technological reasons, the electrodes of the actual sensor and the compensation electrode are preferably applied to the adjacent (inner) glass surfaces.

[0014] If, however, the outer pane of the laminated glazing is the part whose permittivity has the decisive influence on the capacitance measurement signal, then the material property compensation electrode must be placed on the outer surface of this pane. It should be noted that with multi-layer glazing, there are a number of possibilities regarding the critical layer(s), and the location for placing the material property compensation electrode must be selected depending on which layer(s) the dielectric properties of are to be inherently compensated by the use of this additional electrode.

[0015] In another embodiment, the glazing unit is a single-pane glazing unit, with the first and second sensor sections arranged on the first surface and the material property compensation electrode on the second surface of the single glass pane. Here, the critical sensor material component is the glass, and the sensor sections and the compensation electrode are also formed directly on it.

[0016] In a version that is currently of particular practical importance, the capacitive sensor is designed as a humidity sensor for sensing moisture on the inside and / or outside of the glazing unit or in its respective environment.

[0017] As mentioned above, capacitive sensors are also used to detect other physical quantities, and the invention can be used profitably for such additional applications as well.

[0018] From a technological perspective, designs are currently preferred in which the first and second sensor sections and / or the material property compensation electrode have a conductor structure printed or bonded to the respective surface of the glass pane or polymer film, or to an adjacent surface of another component. Specifically, the printed or bonded conductor structure can be transparent, at least in some sections.

[0019] The proposed detection setup comprises, in addition to a glazing unit as described above by way of example, a power supply unit and a readout and evaluation unit. The power supply unit is connected to the second sensor section of the capacitive sensor and to the material property compensation electrode, and is designed to supply the second sensor section and the material property compensation electrode with the same potential. The readout and evaluation unit is designed to read a capacitance signal from the second sensor section of the capacitive sensor and to process this signal to determine a value of the physical quantity.

[0020] The readout and evaluation device is designed in such a way that it can also take into account a voltage signal or a voltage change which originates from the material property compensation electrode on the opposite side of the relevant material layer and which reflects the change of its relevant material property (especially the permittivity).

[0021] The advantages and expediencies of the invention will become apparent from the following description of exemplary embodiments of the invention with reference to the figures. These show: Fig. 1 shows a first embodiment of the glazing unit in a schematic cross-sectional view; Fig. 2 shows a second embodiment of the glazing unit in a schematic cross-sectional view; Fig. 3 shows a schematic representation of an embodiment of the detection arrangement according to the invention in the form of a block diagram.

[0022] Fig. 1 Figure 1 schematically shows a section view of a glazing unit 1 designed as a laminated glass pane, such as can be used as a windshield unit in a passenger car. The glazing unit 1 comprises a first (outer) glass pane 3a and a second (inner) glass pane 3b and a PVB film 5 bonded between them (with adhesive layers not separately labelled).

[0023] In the area shown, the glazing unit 1 is equipped with a humidity sensor 7, which comprises a first sensor section 7a and a second sensor section 7b. The sensor sections 7a and 7b are shown here purely symbolically. Since such capacitive humidity sensors have been known for a long time and are in widespread use, they are familiar to those skilled in the art and therefore do not require a more detailed description here.

[0024] The figure shows that the first and second sensor sections 7a, 7b are arranged between a first surface 5a of the PVB film 5 and the inner surface of the adjacent glass pane 3a. In practice, the sensors typically have conductor structures printed or glued onto the respective glass surface. Depending on the specific design of the glazing unit with integrated sensors, the conductors can be at least partially transparent, for example, made of ITO (indium tin oxide), transparent metallic silver layers, or conductive polymers. Opposite and covering the area of ​​the second sensor section 7b, a material property compensation electrode 9 is attached to the inner surface of the second glass pane 3b, and thus to the second surface 5b of the PVB film 5.

[0025] This additional electrode is connected to the same potential as the second sensor section 7b of the humidity sensor 7, which acts as the signal acquisition section. Insofar as a conventionally formed electric field penetrates the PVB film 5 between sensor sections 7a and 7b, changes in the electrical properties, especially the permittivity, of the PVB film (e.g., due to temperature changes) are compensated inherently by the sensor itself. This is achieved by also generating an electric field between the first sensor section 7a and the material property compensation electrode 9. This electric field is influenced by changes in the permittivity of the PVB film in the same way as the field between sensor sections 7a and 7b.

[0026] It should be noted that the above specification of sensors 7a, 7b is merely exemplary and that the provision of corresponding shielding electrodes or surfaces may also be useful for capacitive sensors with different detection functions and, more generally, for other types of sensors that are affected by changes in the electrical properties of a sensor substrate during operation of the sensor device.

[0027] Fig. 2 Figure 1 shows a modified version compared to the first version, specifically a single-pane glazing unit 1', such as those used in vehicle construction for side windows or in building technology, for example, for interior or exterior windows of buildings in subtropical or tropical regions. Here, the glazing unit 1' comprises a single glass pane 3', and sensor sections 7a', 7b' and a material property compensation electrode 9' with the functions and specifications described above are applied to both surfaces of this pane.

[0028] Fig. 3 schematically shows that a glazing unit 1 of the in Fig. 1 The type shown, with integrated sensor 7 in a vehicle 11, together with an evaluation unit 13, forms a moisture detection arrangement 15. The detection arrangement 15 is connected on the output side to a windshield wiper control unit 17, which controls the windshield wipers 19 of the vehicle 11 in a manner known per se, depending on the detected moisture signals.

[0029] The detection arrangement 15 according to the invention comprises a specially designed power supply unit 21, which is used to supply power to the second sensor section and the material property compensation electrode (see Fig. 1The sensor assembly 7 is configured with the same potential. Within the glazing unit and between it and the power supply unit (for example, in the area of ​​the instrument panel or the vehicle roof), a first connecting line is provided for connecting the first sensor section to a first supply potential, and a second connecting line is provided for connecting the second sensor section and the material property compensation electrode to a second supply potential. In the simplest case, the supply potentials are constant over time, but depending on a specific sensor design and specific sensor functions, they can also have a predetermined time dependency if necessary. Within the glazing unit, the first and second connecting lines can be implemented as adhesive or printed conductors, particularly transparent ones.

[0030] The evaluation unit 13 can be designed to take into account a voltage signal originating from the material property compensation electrode in conjunction with the actual readout signal from the second sensor section. Reference symbol list

[0031] 1; 1'Glazing unit 3a, 3b; 3'Glass pane 5PVB film 5a, 5first and second surface of the PVB film 7Humidity sensor (sensors) 7a, 7b; 7a`, 7b`first and second sensor 9; 9"Material property compensation electrode 11Vehicle 13Differential evaluation unit 15Detection arrangement 17Windscreen wiper control unit 19Windscreen wiper 21Power supply unit

Claims

1. Detection arrangement for capacitive detection of a physical variable on the inside and / or the outside of a vehicle window or building window or in its immediate environment, comprising: - a glazing unit for forming the vehicle window or building window, which has at least one glass pane or polymer film, wherein a capacitive sensor is arranged on a first surface of the or a glass pane or polymer film, which sensor comprises a first sensor section and a second sensor section spaced at a distance therefrom on the first surface, which second sensor section acts as a signal readout section, wherein during operation of the sensor, an electrical field is generated between the first and second sensor section, which field partially penetrates the glass pane or polymer film, wherein a material property compensation electrode is provided on the second surface of the same glass pane or polymer film, opposite the second sensor section, wherein a first connecting line of the first sensor section and a common second connecting line of the second sensor section and of the material property compensation electrode are provided, - a voltage supply unit connected to the second sensor section of the capacitive sensor and to the material property compensation electrode, which is designed for applying the same potential to the second sensor section and to the material property compensation electrode, and - a readout and evaluation device for reading a capacitance signal from the second sensor section of the capacitive sensor and for processing the signal to determine a value of the physical variable, wherein the readout and evaluation device is implemented to take into account a voltage signal originating from the material property compensation electrode.

2. Detection arrangement according to claim 1, implemented as a composite glass pane, which has a first and second glass pane and a polymer film bonded therebetween, wherein the first and second sensor section are arranged on the inner surface of the first glass pane, adjacent the first surface of the polymer film, and the material property compensation electrode is arranged on the inner surface of the second glass pane, adjacent the second surface of the polymer film, or on the outer surface of the second glass pane.

3. Detection arrangement according to claim 1, implemented as a single-pane glazing unit, wherein the first and second sensor section are arranged on the first surface and the material property compensation electrode is arranged on the second surface of the single glass pane.

4. Detection arrangement according to one of the preceding claims, wherein the capacitive sensor is implemented as a moisture sensor for sensing moisture on the inside and / or the outside of the glazing unit or its respective environment.

5. Detection arrangement according to one of the preceding claims, wherein the capacitive sensor is implemented as a touch sensor for detecting touches or the application of pressure on the inside and / or the outside of the glazing unit.

6. Detection arrangement according to one of the preceding claims, wherein the first and second sensor section and / or the material property compensation electrode and the optionally provided first and second connecting line have a conductor structure printed or glued onto the respective surface of the glass pane or polymer film or onto a surface of another component adjacent thereto.

7. Detection arrangement according to claim 6, wherein the printed or glued-on conductor structure is transparent at least in sections.

8. Vehicle with a detection arrangement according to one of the claims 1 through 7.