Sensor device

Abstract

Sensor device for detecting moisture on a disk (4) with a transmitter (2) and a receiver (3) and with an optic (1) arranged between the transmitter (2) and the receiver (3), wherein the optic (1) has an upper plane (13, 23) for connection to a disk (4) and wherein the optic (1) has an output coupling area (8) for coupling the electromagnetic beams from the optic (1) into the disk (4) and an input coupling area (16) for coupling the electromagnetic radiation from the disk (4) into the optic (1), characterized in that the output coupling area (8) has at least two surfaces (9, 10, 11) inclined at an angle of inclination between 2° and 20° relative to the upper plane (13, 23) of the optic (1) in the direction of the input coupling area (16).

Description

[0001] The invention relates to a sensor device for detecting moisture on a windshield, comprising a transmitter and a receiver, and having an optical system arranged between the transmitter and the receiver. The optical system has an upper plane for connection to a windshield, and the optical system has an output region for outputting the electromagnetic radiation from the optical system into the windshield, and an input region for inputting the electromagnetic radiation from the windshield into the optical system. Furthermore, the invention relates to an optical system for such a sensor device and to a motor vehicle having a windshield and a sensor device arranged thereon.

[0002] A first sensor device of the type mentioned above is known from DE 40 06 174 C1. In this first known sensor device, an optical system is arranged on the windshield, into which radiation is introduced at one end by a radiation transmitter. The radiation is reflected several times in the optical system and by the windshield resting against the upper side of the optical system. Depending on the degree of wetting of the windshield, the rays are coupled out of the windshield. A receiver is arranged at the other end of the optical system, which delivers a signal inversely proportional to the amount of precipitation. The sensor device operates on the optical principle of total internal reflection.

[0003] A second sensor device of the type mentioned above is known from DE 10 2007 036 492 B4. DE 100 01 705 A1, DE 10 2008 061 616 A1, and FR 2 722 291 A1 disclose further sensor devices.

[0004] The fundamental problem is that the space available for the sensor device is becoming increasingly smaller. This also means that the surface area of ​​the optics forming the sensing area is becoming increasingly smaller. The resulting signal becomes less accurate.

[0005] The invention is therefore based on the object of creating a sensor device of the type mentioned at the outset which, even with a small design, still provides a usable signal for detecting moisture on a window.

[0006] This problem is solved by a sensor device having the features of patent claim 1. With regard to an optical system, the solution is achieved by the features of patent claim 9 and with regard to a motor vehicle by the features of patent claim 10.

[0007] In a sensor device for detecting moisture on a windshield, comprising a transmitter and a receiver, and an optical system arranged between the transmitter and the receiver, the optical system having an upper plane for connection to a windshield, and the optical system having an output region for coupling the electromagnetic radiation from the optical system into the windshield, and a coupling region for coupling the electromagnetic radiation from the windshield into the optical system, it is essential to the invention that the output region has at least two surfaces inclined at an angle of between 2° and 20° relative to the upper plane of the optical system in the direction of the coupling region. This ensures that the electromagnetic radiation introduced into the optical system by the transmitter is particularly effectively coupled out of the optical system in the output region and coupled into the windshield.The upper plane of the optics does not refer to a continuous plane in a flat sense, but rather to the entire area adjacent to the disk. This plane is not completely flat, but rather has, for example, the inclined surfaces according to the invention in the coupling-out area.

[0008] The inclined surfaces preferably have an angle of inclination of between 4° and 10° relative to the upper plane. More preferably, the inclined surfaces have an angle of 5° relative to the upper plane of the optics. Since the receiver transmits the electromagnetic radiation laterally into the optics, the angle at which the electromagnetic rays hit the inclined surfaces is greater than for non-inclined surfaces. In a particularly preferred embodiment, the decoupling region has four inclined surfaces. Of these four inclined surfaces, at least two are inclined in the direction of the coupling region. However, one inclined surface is preferably inclined, or in another embodiment, two of the inclined surfaces are inclined in the direction of the transmitter.

[0009] In another preferred embodiment of the invention, the coupling region also has at least one surface inclined relative to the upper plane of the optics. The coupling region is the region in which the light from the windshield is coupled into the optics. This is arranged adjacent to the receiver of the sensor device. This configuration of the geometry of the coupling region achieves particularly good coupling of the light from the windshield into the coupling region. The inclined surface of the coupling region preferably has an angle of inclination between 2° and 20° relative to the upper plane of the optics and more preferably an angle of inclination between 4° and 10° relative to the upper plane of the optics. More preferably, the inclined surface has an angle of 5° relative to the upper plane of the optics.In a preferred embodiment, the coupling region has at least two inclined surfaces whose inclined surfaces are oriented opposite to one another, in particular with an inclination converging toward one another. In an alternative preferred embodiment, the coupling region has two or more inclined surfaces whose inclination converges toward the coupling-out region. These are preferably formed at the edges, i.e., particularly close to the receiver. The inclined surface furthest from the receiver, or the furthest and second-furthest inclined surfaces, are preferably inclined toward the receiver, i.e., oppositely inclined to the aforementioned inclined surfaces.

[0010] In another embodiment of the invention, the optics between the output coupling region and the input coupling region have a convex shape on their underside, i.e., opposite the upper plane. This specially adapted geometric shape on the underside of the optics achieves total internal reflection, so that the electromagnetic rays inside the optics are reflected with virtually no loss. This convex shape is arranged between the input coupling region and the output coupling region. The inclined surfaces of the output coupling region are inclined toward the input coupling region. Only the inclined surfaces that are completely above the intermediate region of the underside, which has the convex shape, are inclined toward the input coupling region.

[0011] Conversely, this also applies to the inclined surfaces of the coupling area. Only the inclined surfaces in the coupling area that are completely above the intermediate area with the convex shape on the bottom are inclined toward the coupling area or the receiver.

[0012] In another preferred development of the invention, the optics have a central, flat region on their upper side between the output coupling region and the input coupling region. This region ultimately separates the input coupling region and the output coupling region from one another. On the underside, there is an intermediate region that overlaps the middle sections of the input coupling region and the output coupling region. According to another preferred development of the invention, the optics have an input coupling lens opposite the transmitter, which is designed like a bowl with a convex, outwardly projecting base. This results in particularly good focusing and collection of scattered light. This results in maximum light coupling into the optics. The sensor device, including the transmitter and the receiver, which are preferably designed as diodes, is preferably tuned to wavelengths from 880 nm to 920 nm.

[0013] Another aspect of the invention lies in the provision of an optical system for the above-mentioned sensor device, wherein the optical system has an upper plane for connection to a disk, and wherein the optical system has an output region that serves to output the electromagnetic radiation from the optical system into the disk, and an input region that serves to input the electromagnetic radiation from the disk into the optical system. Furthermore, the output region of the optical system according to the invention has at least two surfaces inclined at an angle of between 2° and 20° relative to the upper plane of the optical system in the direction of the input region.

[0014] A further aspect of the invention consists in the design of a motor vehicle with a windshield and a sensor device arranged thereon for detecting moisture on the windshield. The sensor device is designed according to the above description.

[0015] The invention is further explained below with reference to an exemplary embodiment illustrated in the drawing. The schematic representations show in detail: Fig. 1: a cross-section through a sensor device according to the invention in a schematic representation with a disc arranged thereon; Fig. 2: a perspective view of the optics of the sensor device according to Fig. 1; Fig. 3: a cross section through the sensor device according to the invention in a housing.

[0016] In Fig. 1 is a schematic cross-section through a sensor device according to the invention with a disk 4 arranged thereon. The sensor device essentially comprises an optic 1, a transmitter 2, and a receiver 3. The optic 1 is arranged adjacent to a disk 4. For this purpose, the optic 1 has an upper plane 13 for connection to the disk. The optic 1 does not have a continuous upper plane, but is only partially flat in the upper region. The term upper plane refers to the upper side, which is intended for connection to the disk 4. The transmitter 2 is typically designed as a diode and radiates electromagnetic radiation into the optic 1. For this purpose, the optic 1 has, opposite the transmitter 2, a coupling optic 5, which is designed in the manner of a bowl 7 with a convex, outward-projecting base 6.The electromagnetic rays then pass from the optics 1 via a coupling-out region 8 into the pane 4. The electromagnetic rays are reflected at the top side of the pane 4 and are ultimately reflected multiple times between the optics 1 or its underside 21 and the top side of the pane 4. When the pane 4 is wetted with water or rain, electromagnetic rays are coupled out of this system and the intensity decreases. The decrease in intensity at the receiver 3, which is typically also a diode, is then a measure of the wetting of the pane 4 on the top side. In the illustrated embodiment, the coupling-out region 8 has three inclined surfaces 9, 10 and 11, which are inclined towards the receiver 3 or a coupling-in region 16 arranged near the receiver 3. The angle α is between 2 and 20°, preferably 4° to 10° and in particular 5° to 8°.This geometry on the top side of the light guide results in particularly high coupling of the light from the optics 1 and particularly good coupling of the light into the disc 4. Furthermore, a surface 14 is provided which is mirror-symmetrical opposite the inclined surface 11 and is inclined in the opposite direction, i.e. towards the receiver of the transmitter 2. The inclined surfaces 11 and 14 are separated from one another by a tip 12 with a triangular cross-section. The surface 14 inclined towards the transmitter 2 is located completely above the underside 21, insofar as this has a convex shape and lies between the outcoupling region 16 and the coupling region 8. A central flat region 13 is provided approximately in the middle of the optics 1. This is actually flat and lies adjacent to the disc 4. In the right-hand area of ​​the . Fig. 1, i.e. adjacent to the receiver 3, a coupling region 16 is provided, in which the electromagnetic rays from the disk 4 are maximally coupled into the optics 1 or coupled out of the disk 4. Here, too, several inclined surfaces are provided. These are in particular the surfaces 17 and 20, which are immediately adjacent to the receiver 3 and are inclined in the direction of the transmitter 2 or in the direction of the coupling-out region 8. The surfaces 17 and 20 are inclined at an angle β relative to the upper plane 13. The angle of inclination is between 2° and 20°, in particular between 4° and 10° and particularly preferably between 5° and 8°. Adjacent to the transmitter 2, a further inclined surface 18 is provided, which is inclined in the direction of the receiver 3. The surfaces 18 and 17 are arranged symmetrically to each other to the right and left to form a structure 19 with a triangular cross-section.Surface 18 is located entirely above the convex underside 21 of the optics 1. Next to it, in the direction of the transmitter 2, is another inclined surface 15, which is also inclined toward the receiver 3, i.e., has the same inclination as the inclined surface 18. Surfaces 15, 17, 18, and 20 are all inclined at the same angle, specifically at an angle between 4° and 8°. Surfaces 15 and 18 are inclined toward the receiver 3, while surfaces 17 and 20 are inclined toward the transmitter 2. These two groups of surfaces are therefore oppositely inclined to each other.

[0017] In Fig. 2 shows an optic 1 in perspective view. In contrast to the Fig. 1, neither the disc 4, nor the transmitter 2, nor the receiver 3 are shown here. Clearly visible here is the coupling optics 5, which is designed like a dish 7 and has a base 6 that protrudes convexly outwards, i.e. in the direction of the transmitter 2. The upper plane, which is intended to rest on the disc 4, is also flat in a central region 13 and in a surrounding frame 23 and is intended to rest on the disc 4. In the remaining regions, essentially the inclined surfaces 9, 10, 11 and 14 of the coupling-out region 8 and the inclined surfaces 15, 17, 18 and 20 of the coupling-in region 16 are provided. An output coupling optics 22 is provided adjacent to the receiver 3. This is essentially designed as a convex spherical surface.

[0018] In Fig. 3 is comparable to Fig. 1 shows the device according to the invention in a cross-section. In contrast to Fig.1, the illustration is reversed, i.e., the transmitter 2 is located on the right and the receiver 3 is located on the left. Identical parts are identified by the same reference numerals. A housing 30 is provided in which the transmitter 2 is arranged on a circuit board 31 and the receiver 3 is arranged on a circuit board 32. Transmitter 2 and receiver 3 are preferably diodes operating in the infrared range from 880 nm to 920 nm.

[0019] The angles for the inclined surfaces 9, 10, 11, 14, 15, 17, 18, and 20 are shown. These are 5° for the incline and 47° for the short inclined surface. The convex underside 21 is formed as part of a circular circumference.

[0020] All features mentioned in the above description and in the claims can be combined in any desired manner with the features of the independent claim. The disclosure of the invention is therefore not limited to the described or claimed feature combinations; rather, all feature combinations that are meaningful within the scope of the invention are to be considered disclosed.

Claims

[1] Sensor device for detecting moisture on a pane (4) with a transmitter (2) and a receiver (3) and with an optic (1) arranged between the transmitter (2) and the receiver (3), wherein the optic (1) has an upper plane (13, 23) for connection to a pane (4) and wherein the optic (1) has a decoupling region (8) which serves to decouple the electromagnetic radiation from the optic (1) into the pane (4), and a coupling region (16) which serves to couple the electromagnetic radiation from the pane (4) into the optic (1), characterized by that the coupling-out region (8) has at least two surfaces (9, 10, 11) inclined at an angle of inclination between 2° and 20° relative to the upper plane (13, 23) of the optics (1) in the direction of the coupling-in region (16). [2] Sensor device according to claim 1, characterized bythat the inclined surfaces (9, 10, 11) of the coupling-out region (8) have an angle of inclination between 4° and 10° relative to the upper plane (13, 23). [3] Sensor device according to one of the preceding claims, characterized by that the coupling region (16) has at least one surface (15, 17, 18, 20) inclined relative to the upper plane (13, 23) of the optics (1). [4] Sensor device according to claim 3, characterized by that the inclined surface (15, 17, 18, 20) of the coupling region (16) has an angle of inclination between 2° and 20° relative to the upper plane (13, 23) of the optics (1), in particular between 4° and 10° relative to the upper plane (13, 23) of the optics (1). [5] Sensor device according to claim 3 or claim 4, characterized bythat the coupling region (16) has at least two inclined surfaces (15, 17, 18, 20) and that at least two of these inclined surfaces (17, 18) of the coupling region (16) are oriented opposite to one another, in particular are oriented so as to converge towards one another in terms of inclination. [6] Sensor device according to one of the preceding claims, characterized by that the optics (1) between the coupling-out region (8) and the coupling-in region (16) has a convex shape on its underside, i.e. opposite the upper plane (13, 23) of the optics (1). [7] Sensor device according to one of the preceding claims, characterized by that the optics (1) has, on its upper side facing the disc (4), between the coupling-out region (8) and the coupling-in region (16), a central flat region (13) with which the upper plane (13, 23) of the optics (1) is formed. [8] Sensor device according to one of the preceding claims, characterized bythat the optics (1) have a coupling optics (5) opposite the transmitter (2), which is designed in the manner of a bowl (7) with a convex outwardly projecting base (6). [9] Optics (1) for a sensor device according to one of the preceding claims, having an upper plane (13, 23) for connection to a disk (4) and a coupling-out region (8) which serves to couple the electromagnetic radiation out of the optics (1) into the disk (4), and a coupling-in region (16) which serves to couple the electromagnetic radiation from the disk (4) into the optics (1), wherein the coupling-out region (8) has at least two surfaces (9, 10, 11) inclined at an angle of inclination between 2° and 20° relative to the upper plane (13, 23) of the optics (1) in the direction of the coupling-in region (16). [10] Motor vehicle with a pane (4), in particular a windshield, and a sensor device arranged thereon according to one of claims 1 to 8.

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