DE102008043610A1 - Sensor device i.e. capacitive rain sensor, for detection of rain and/or rain drops on panel of motor vehicle, has two sensor elements that are laterally arranged and/or overlapped on opposite sides of panel device of vehicle - Google Patents

Abstract

The device (12) has two sensor elements (20, 22) that are laterally arranged and/or overlapped on opposite sides of a panel device (10) of a vehicle. The pane device has two outer layers (14) made of glass and an intermediate layer (18) made of glass and/or plastic i.e. polyvinyl butyral, and arranged between the outer layers. The sensor elements have capacitors (C1, C2) including two electrodes that are interlaced, where a dielectric is provided between the electrodes, which form a double helix.

Description

The The invention relates to a capacitive rain sensor for detecting Rain or raindrops on a window of a vehicle, in particular of a motor vehicle.

A The comfort features in motor vehicles today is as needed automatic activation of windscreen wipers. To such a function To realize a rainfall is provided, the rain on the windshield detected.

From the US 6,373,263 B1 For example, a capacitive sensor for detecting raindrops on an outer surface of a windshield of a vehicle is known. In this case, three capacitive sensors are arranged on the inside of the windshield. One of the capacitive sensors serves to detect raindrops, while the other two sensors form compensation sensors for temperature compensation. The sensors are shielded to protect them from debris on the inside of the disk, as well as capacitive effects from objects near the sensors, such as the hand of a vehicle occupant.

Furthermore, optical rain sensors are on the market. Such optical rain sensors, as used for example in the DE 601 27 130 T2 However, they have various disadvantages. This may result in wiping through the wiper device, although the wafers are dry or not raining. This is because the surrounding light conditions have a significant influence on the operation of the optical rain sensor and therefore may also lead to erroneous detection of raindrops, although it does not rain. Furthermore, these sensors are relatively large and therefore conspicuous. Moreover, the sensors are relatively expensive.

Capacitive rain sensors, as previously with reference, for example, to the US 6,373,263 B1 are based on a surface capacity, with the value of the capacity increasing as it rains. However, there are two main problems. The value for the capacitance may be affected by any material having a relative dielectric constant greater than one that is near or equal to the surface of the capacitor. The movements of a driver or passenger may therefore mislead the system. An approaching hand can produce a signal similar to rain that falls on the disk from the outside.

One second problem is a rapid increase in temperature, for example due to heating or heating of the windshield or moving out of a tunnel into the brightness. This changes the dielectric constant or dielectric constant the glass of the windshield very quickly, so it too can lead to a misleading of the system.

With regard to the first problem, an electrical shield is used. In other words, a conductive plate is inserted between the sensor and the passenger compartment. However, this can in turn lead to material problems and parasitic capacity problems. With regard to the second problem is described in the above US 6,373,263 B1 used a differential, capacitive rain sensor for the windshield.

According to the Invention is now provided an improved sensor device for detecting rain or raindrops on a disc of a Vehicle, in particular a motor vehicle.

The Sensor device according to the invention for detection of rain or raindrops on a disk device has at least two sensor elements, wherein the sensor elements on opposite sides of the disk device or on opposite sides within the disc means are arranged.

The inventive sensor device has this the advantage that in this way different capacities can be generated at the capacitors, for example a person in the interior comes very close to the ticket or himself the temperature of the disc changes rapidly due to solar radiation. When rain falls on the outside of the window On the other hand, the capacities remain the same. On This way can be very easily and reliably determined whether rain falls on the discs or whether the change the capacitances of the capacitors of the sensor elements other causes than rain.

Further preferred embodiments of the invention are in the Subclaims described.

In one embodiment of the invention, the disk device, for example, at least three layers. The two outer layers may consist of glass or have this or have one or more glass layers. At least one intermediate layer may be arranged between the two layers. This intermediate layer may consist of or comprise glass and / or plastic. The intermediate layer may comprise, for example, one or more layers of glass and / or plastic. The arrangement of the sensor device or its sensor elements between these layers, the sensor elements be protected very easily, without an outer cover is necessary. In principle, however, it is also possible to provide the sensor device with a disk device, for example, from only one or two layers. In a disk device of two layers z. B. a sensor element between the two layers and a sensor element on the inside of the disc device, which faces the vehicle interior, are arranged. This sensor element can then be additionally provided with protection, for example against contamination.

In a further embodiment of the invention the two sensor elements are so opposite arranged so that they completely overlap, partially overlap or do not overlap one another or are arranged laterally spaced from each other. An overlapping Arrangement has the advantage that the sensor device has a very allows compact construction.

In another embodiment of the invention are the sensor elements of the sensor device or their capacitors mirror image, arranged opposite each other. The capacitors each have the same structure or their electrodes are formed in the same way, for example as one another crossed combs or double spiral etc ..

According to one Another embodiment of the invention is one or both Electrodes of the capacitor of a sensor element made of wire, a transparent electrical wiring material, an opaque electrical wiring material and / or a partially opaque electrical conductor material. The transparent electrical wiring material, such as ITO, has the advantage that the sensor device is substantially invisible for a passenger in the interior of the vehicle is and therefore allows a lot of leeway for the arrangement of the sensor device in or on the disc device of the vehicle.

embodiments The invention will be described below with reference to the schematic figures explained in detail the drawing. Show it:

1 a schematic sectional view through a pane of a vehicle with a sensor device according to an embodiment of the invention;

2 a first embodiment of a sensor element of the sensor device according to the invention;

3 a second embodiment of a sensor element of the sensor device according to the invention; and

4 A third embodiment of a sensor element of the sensor device according to the invention.

In all figures are the same or functionally identical elements and devices - if nothing else is indicated - with the same reference numerals been provided.

In 1 is first a schematic sectional view through a disc or disc device 10 a vehicle, which with a sensor device according to the invention 12 is provided. A disc or disc device 10 For example, a vehicle, such as a windshield of a motor vehicle, generally has, for example, two layers 14 . 16 Made of a transparent material. The material is usually glass, but may in principle also consist of another transparent material or have this, such as plastic. The invention is not limited to glass. Between these two first and second layers 14 . 16 , z. B. glass, is further at least one other layer or intermediate layer 18 arranged, for example made of plastic. The plastic liner 18 This may for example consist of polyvinyl butyral or PVB or have this. In principle, however, for example, any other suitable plastic or plastic combination as an intermediate layer 18 be provided. The invention is not based on PVB as an intermediate layer 18 limited. In addition to plastic, the liner 18 also made of a different transparent material. Basically also made of glass or at least exhibit this.

In the example in 1 now becomes a sensor device 12 provided which, for example, at least two sensor elements 20 . 22 having. The sensor elements 20 . 22 in each case have at least one capacitor or surface capacitor. This capacitor is in 1 not shown.

As in the example in 1 is further shown, a first sensor element 20 with its respective surface capacitor between the first, outer layer 14 of glass and the liner 18 arranged. Furthermore, the other second sensor element becomes 22 with its surface capacitor between the second, inner layer 16 of glass and the liner 18 arranged. The sensor elements 20 . 22 are thus on opposite sides of the liner 18 arranged and for example on the intermediate layer 18 and / or the particular situation 14 . 16 attached or attached. This means that the sensor elements 20 . 22 respectively. whose surface capacitors are preferably opposite each other or, for example, are arranged in mirror image opposite one another. But it is also possible the sensor elements 20 . 22 or the surface capacitors offset from each other to arrange, wherein the surface capacitors of the individual sensor elements 20 . 22 overlap (not shown). Alternatively, the sensor elements 20 . 22 or whose surface capacitors are also arranged offset from one another in such a way that there is no overlap between the surface capacitors (not shown). In this case, however, the surface capacitors are preferably arranged near or adjacent to one another, for example.

Furthermore, in addition to a disc device 10 with three layers 14 . 16 . 18 also a disc device 10 for example, with only one layer, z. B. made of glass or two layers, for. B. of glass and / or Kunstsoff be provided. In only one position, the two sensor elements 20 . 22 also disposed on opposite sides of the one layer of the disc means (not shown). Since, in this case, a sensor element is arranged on the outside of the disk device and a sensor element on the inside of the disk device, toward the interior of the vehicle, both sensor elements must be additionally provided with a protective cover. In a disc device with two layers (not shown), a sensor element between the two layers can be arranged and a sensor element on the outside or inside of the disc device opposite to the first sensor element. In this case, for example, only the outer sensor element can be provided with an additional protective cover or the like. In a disk device of four layers or more layers (not shown), the sensor elements may in turn be arranged on opposite sides, for example a layer, wherein they are preferably arranged or embedded within the disk device, as in the embodiment with three layers.

In this way, a sensor device can now 12 or a combination of sensor elements 20 . 22 which can provide a difference between the dielectric inside and outside. The capacitor of the sensor element 20 which in this case is closer to the outside environment is referred to as the first, outer capacitor C1. The other capacitor of the other sensor element 22 which is closer to the passengers in the interior of the vehicle is referred to as the second, inner capacitor C2. If rain now occurs, the respective capacitance of the first and second capacitors C1 and C2 changes with increasing rain or increasing raindrops to different degrees. In this case, C1> C2, ie the capacity of the first, outer capacitor C1 is greater than the capacity of the second, inner capacitor C2 when it rains.

In the case that, for example, the dielectric of the disc 10 on the inside changes, for example, by a passenger from the inside to the disc or disc device 10 sums, the respective capacitance of the first and second capacitors C1 and C2 also changes differently. It is true that the capacitance of the second, inner capacitor C2 is greater than the capacitance of the first, outer capacitor C1. It therefore applies C2> C1. This change in the capacitance of the sensor elements 20 . 22 was also experimentally tested and proven in a laboratory of Rober Bosch.

In the case of a temperature change of the disc or disc device 10 For example, with a temperature increase due to solar radiation through the disc, the capacitance of the two capacitors C1 and C2 changes to the same extent. In other words, the respective capacitance of the two capacitors C1 and C2 is substantially equal. Thus, C1 = C2. This was also tested and proven in experiments.

In this way, it can be determined very simply and reliably, based on a comparison of the capacitances of the first, outer capacitor C1 and the second, inner capacitor C2, whether raindrops actually hit the disk 10 with the sensor device 12 fall or whether the change in the capacitance of the two capacitors C1, C2 z. B. based on a rapid change in temperature or, for example, a series of contacts of the disc 10 are by a passenger in the interior. It can be dispensed with additional measures, such as a shield of the sensor elements or an additional temperature measurement of the disc. Further, no complex algorithms are needed to determine if the rain sensor is actually detecting raindrops or not. Furthermore, no different plate spacings are necessary, of plates which are arranged for example between the capacitors.

In 2 is a first embodiment of a sensor element 20 respectively. 22 the sensor device according to the invention 12 shown. The sensor element 20 respectively. 22 has, for example, a capacitor or here surface capacitor 24 on. The surface capacitor 24 is thereby by two electrodes 26 . 28 educated. The two electrodes 26 . 28 each have a comb-shaped shape and are, for example, one another entangled. Between the two intermeshed comb-shaped electrodes 26 . 28 is a dielectric 30 arranged.

Furthermore, in 3 a second embodiment of a sensor element 20 respectively. 22 the sensor device according to the invention 12 shown. In this case, the sensor element 20 respectively. 22 also a capacitor or here surface capacitor 24 on. As in 3 is shown, the surface capacitor 24 through two electrodes 26 . 28 educated. The electrodes 26 . 28 each have the form of a spiral, wherein the spiral-shaped electrodes 26 . 28 are interlaced or form a double spiral. Between the spiral electrodes 26 . 28 is a dielectric 30 intended. One or both of the spiral electrodes 26 . 28 can be formed, for example, angular, as in 3 is shown, or even round (not shown). This also applies to the two comb-shaped electrodes 26 . 28 in 2 , One or both electrodes 26 . 28 In addition to the angular shape, as in 2 is also shown to have a round or rounded shape (not shown).

In principle, however, any other form of capacitor can be used 24 be provided or of electrodes 26 . 28 that the capacitor 24 form. For example, two nested round, oval and / or square electrodes may be provided, wherein a dielectric 30 between the electrodes 26 . 28 is arranged. In the example in 4 is an outer ring-shaped electrode 26 provided in which an inner, circular or punctiform electrode 28 is provided. Instead of the point-shaped electrode 28 It is also possible to provide a further inner, annular electrode, which is filled with a dielectric in the interior (not shown).

The electrodes 26 . 28 as exemplified in the 2 . 3 and 4 can be formed, for example, from a transparent or substantially transparent electrical conductor material, for example ITO (indium tin oxide), and / or be formed from wire, wherein the wire is preferably formed as thin as possible, so that the electrodes for a vehicle occupants as invisible as possible are. In principle, however, the electrodes can also be produced from a suitable opaque or partially opaque material. In this case, the sensor device can be arranged, for example, in a tinted area of a vehicle window, where it is less noticeable.

The Electrodes of the first and second capacitors C1, C2 are, for example connected to an evaluation device (not shown) or coupled. The evaluation device takes the determined quantities the sensor elements and their signals and evaluates, for example the determined sizes (capacities etc.) or signals of the sensor elements or their capacitors C1 and C2 and forwards the result as control information, for example for a windshield wiper to a windshield wiper device (not shown) or an associated on-board electronics (not shown). The evaluation device can, for example, a be separate evaluation, for example, the on-board electronics and / or a windshield wiper device is coupled or even part be the on-board electronics or windscreen wiper device. On Basis of the results of the evaluation, for example, here the capacities the sensor elements or their capacitors is a windshield wiper device controlled accordingly.

The sensor device according to the invention may each have identical sensor elements, for example two sensor elements 26 . 28 as they are in 2 . 3 or 4 are shown. Furthermore, the sensor elements of the sensor device can also be different. So can the sensor elements 26 . 28 according to the 2 to 4 for example, be combined with each other. The sensor device according to the invention 12 has, as described above, the advantage that movements of the human body and other dielectrics within the vehicle, as well as changes in temperature of the disc, for example due to sunshine, rain falling on the vehicle can be distinguished very easily and with little effort.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - US 6373263 B1 [0003, 0005, 0007]
• - DE 60127130 T2 [0004]

Claims (10)

Sensor device ( 12 ) for detecting rain on a disk device ( 10 ) of a vehicle, characterized in that the sensor device ( 12 ) at least two sensor elements ( 20 . 22 ) located on opposite sides of the disk device ( 10 ) are arranged. Sensor device according to claim 1, characterized in that the disc device ( 10 ), for example, at least three layers ( 14 . 16 . 18 ), wherein the two outer layers ( 14 . 16 ) consist of glass or have this and the interposed layer or intermediate layer ( 18 ) consists of or comprises glass and / or plastic. Sensor device according to claim 2, characterized that the plastic is made of polyvinyl butyral (PVB) or this having. Sensor device according to claim 2 or 3, characterized in that a sensor element ( 20 ) between the first outer layer ( 14 ) of the disk device ( 10 ) and the intermediate layer ( 18 ) and the other sensor element ( 22 ) between the second inner bearing ( 16 ) and the intermediate layer ( 18 ). Sensor device according to one of claims 1 to 4, characterized in that the two sensor elements ( 20 . 22 ) are arranged opposite one another so that they completely overlap, partly overlap or do not overlap one another or are arranged laterally spaced apart from one another. Sensor device according to one of claims 1 to 5, characterized in that the respective sensor element ( 20 . 22 ) has at least one capacitor (C1, C2), the capacitor (C1, C2) having at least two electrodes ( 26 . 28 ) having. Sensor device according to claim 6, characterized in that the electrodes ( 26 . 28 ) at least one capacitor (C1, C2) of a sensor element ( 20 . 22 ) or both sensor elements ( 20 . 22 ) each have a comb shape, wherein the electrodes ( 26 . 28 ) are interlaced, wherein between the electrodes ( 26 . 28 ) a dielectric ( 30 ) is provided. Sensor device according to claim 6 or 7, characterized in that the electrodes ( 26 . 28 ) at least one capacitor (C1, C2) of a sensor element ( 20 . 22 ) or both sensor elements ( 20 . 22 ) each have a spiral shape, wherein the electrodes ( 26 . 28 ) form a double spiral, wherein between the electrodes ( 26 . 28 ) a dielectric ( 30 ) is provided. Sensor device according to one of claims 6 to 8, characterized in that one or both electrodes ( 26 . 28 ) of the capacitor (C1, C2) of a sensor element ( 20 . 22 ) of wire, a transparent electrical conductor material, an opaque electrical conductor material and / or a partially opaque electrical conductor material. Sensor device according to one of claims 1 to 9, characterized in that the sensor elements ( 20 . 22 ) of the sensor device ( 12 ) are arranged in mirror image opposite one another.