Abstract
A sensor device including a sensor element, a cover panel, and a detection device detecting contaminants on the cover panel. The detection device includes an emitter emitting light, a coupling-in device coupling light into the cover panel, a decoupling device decoupling light from the cover panel, and a detector. The emitter and the coupling-in device couple light into the cover panel at a plurality of angles, and due to total reflection within the cover panel, the light propagates to the decoupling device and reaches the detector. If contaminants are on the cover panel, the total reflection for light coupled in at an angle within an extinction range is at least partially extinguished, and the detector is configured to detect the extinguishing of the total reflection for these angles. The detection device is configured to deduce the type of contaminant from the angles for which the total reflection has been extinguished.
Claims
1-10. (canceled)
11. A sensor device, comprising: a sensor element; a cover panel that protects the sensor element from environmental influences; and a detection device configured to detect contaminants on the cover panel, the detection device including an emitter configured to emit light, a coupling-in device configured to couple light into the cover panel, a decoupling device configured to decouple light from the cover panel, and a detector, the emitter and the coupling-in device being configured and arranged in such a way that light is coupled into the cover panel at a plurality of angles, and due to total reflection within the cover panel, the light propagates up to the decoupling device and reaches the detector, and when contaminants are present on the cover panel, the total reflection for light that has been coupled in at angles within an extinction range, which is a function of a refractive index of the contaminants, is at least partially extinguished, the detector being configured to detect the extinguishing of the total reflection for the angles, and the detection device being configured to deduce a type of contaminant from the angles for which the total reflection has been extinguished.
12. The sensor device as recited in claim 11, wherein the emitter is configured to emit light in the form of a divergent light beam.
13. The sensor device as recited in claim 11, wherein the emitter is a light-emitting diode or as a laser diode.
14. The sensor device as recited in claim 11, wherein the coupling-in device and/or the decoupling device is a prism or a hologram or an optical lattice or a beveled surface of the cover panel.
15. The sensor device as recited in claim 11, wherein the detection device includes multiple spatially distributed emitters and/or detectors.
16. The sensor device as recited in claim 11, wherein the detector a CCD or an array of photodiodes.
17. The sensor device as recited in claim 11, further comprising: a cleaning device configured to clean the cover panel, the cleaning device being operable as a function of the type of contaminant.
18. The sensor device as recited in claim 17, wherein the cleaning device includes a spray device configured to apply a liquid to the cover panel, the cleaning device being configured to activate the spray device as a function of the type of contaminant.
19. The sensor device as recited in claim 11, wherein the cover panel is in the form of a circular cylinder having a cylinder axis, the emitter and the detector being configured to rotate about the cylinder axis.
20. The sensor device as recited in claim 11, wherein the sensor element is a LIDAR sensor or a video camera.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] Exemplary embodiments of the present invention are described in greater detail based on the figures and the description below.
[0038] FIG. 1 shows a schematic illustration of a sensor device, including a detection device for detecting contaminants on a cover panel, in accordance with an example embodiment of the present invention.
[0039] FIG. 2 shows a schematic illustration of the measuring principle.
[0040] FIGS. 3a and 3b show a schematic illustration of the propagation of three different light beams without contaminants.
[0041] FIGS. 4a and 4b show schematic propagation of three light beams when a first contaminant is present.
[0042] FIGS. 5a and 5b show the propagation of three light beams when a second contaminant is present.
[0043] FIG. 6 shows a sensor device including a cylindrical cover panel, in accordance with an example embodiment of the present invention.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0044] In the following description of the specific example embodiments of the present invention, identical or similar elements are denoted by the same reference numeral, and a repeated description of these elements is dispensed with in individual cases. The subject matter of the present invention is illustrated only schematically in the figures.
[0045] FIG. 1 shows a schematic illustration of a sensor device 10. Sensor device 10 includes a sensor element 12 with which data about the surroundings in which sensor device 10 is situated may be detected. For this purpose, sensor element 12 is configured to receive electromagnetic radiation and optionally also to emit electromagnetic radiation. Sensor element 12 is situated in a housing 14 that is closed by a cover panel 16. Cover panel 16 protects sensor element 12 from environmental influences. At the same time, cover panel 16 allows electromagnetic radiation to reach element 12, and conversely, optionally allows electromagnetic radiation emitted by sensor element 12 to be released into the surroundings.
[0046] If sensor element 12 is designed as an optical camera, cover panel 16 is transparent to visible light. If sensor element 12 is an infrared camera, for example, cover panel 16 is transparent to infrared light and optionally may be nontransparent to visible light. A further example of a sensor element 12 is a LIDAR sensor, with which objects in the surroundings of sensor device 10 may be detected and their distance from sensor device 10 may be determined.
[0047] Sensor device 10 also includes a detection device 100 for detecting deposits on cover panel 16. In addition, the specific embodiment of sensor device 10 illustrated in FIG. 1 includes a cleaning device 200 via which contaminants 110 may be removed from cover panel 16.
[0048] FIG. 2 schematically shows detection device 100 (cf. FIG. 1) via which deposits 110 on a surface of cover panel 16 may be detected. For this purpose, detection device 100 includes an emitter 102 that is designed as a light-emitting diode, for example, and that emits light 105 to be coupled into cover panel 16. Light 105 to be coupled in reaches coupling-in means (i.e., coupling-in device) 104 and is coupled into cover panel 16 by coupling-in means 104. Prior to the coupling-in, light 105 to be coupled in may be influenced by a first optical element 112 situated between emitter 102 and coupling-in means 104. In the example illustrated in FIG. 2, first optical element 112 is designed as a diffuser. The coupled-in light propagates within cover panel 16 in the direction of decoupling means (i.e., decoupling device) 106, and exits there as decoupled light 107. The light propagates within cover panel 16 utilizing the total reflection, the light propagating, from coupling-in means 104 to decoupling means 106, by multiple reflections at the surfaces of cover panel 16. If no contaminants 110 are situated on the surface of cover panel 16, the critical angle determined for the total reflection is specified by the refractive index of the material of cover panel 16 and the refractive index of the surrounding air. However, if a contaminant 110 is situated on the surface of cover panel 16, the critical angle at which total reflection within cover panel 16 is possible is reduced at the location of the contaminant 110, due to the refractive index of contaminant 110, which is different from that of air. The degree of reduction of the critical angle is a function of the refractive index of contaminant 110. Since the total reflection now is no longer possible for all angles at which light 105 to be coupled in has been coupled into cover panel 16, a partial quantity 111 of the light is now decoupled at the position of contaminant 110.
[0049] By analyzing decoupled light 107 via a detector 108, it may be determined for which angles the total reflection within cover panel 16 is possible, and for which angles it is not possible. Based on this information, it may be derived whether a contaminant 110 is situated on cover panel 16, and the refractive index of this contaminant 110 may be deduced. Since different substances have different refractive indices, for example water has a refractive index of approximately 1.33 and oil typically has a refractive index in the range of approximately 1.4-1.6, a conclusion regarding the type of contaminant 110 is possible solely via the refractive index. Prior to striking detector 108, decoupled light 107 is advantageously influenced by a second optical element 114, which in the example illustrated in FIG. 2 is designed as a lens.
[0050] FIG. 3a illustrates the profile of three examples of light beams of light 105 to be coupled in via cover panel 16. Coupling-in means 104 are designed here by way of example as a beveled surface of cover panel 16. Similarly, decoupling means 106 are likewise designed as a beveled surface of cover panel 16.
[0051] In the situation illustrated in FIG. 3a, no contaminants 110 (cf. FIG. 2) are situated on cover panel 16, so that total reflection within cover panel 16 is possible for all three depicted beams of light 105 to be coupled in. For decoupled light 107, each of the three beams leaves cover panel 16 at a different angle, so that they strike detector 108 at a different detector position P in each case. Detector position P may be correspondingly associated with a propagation angle in cover panel 16.
[0052] FIG. 3b illustrates a diagram that depicts intensity I of decoupled light 107, ascertained by detector 108, as a function of detector position P. As is apparent from the illustration according to FIG. 3b, a high intensity I is measured for all three depicted light beams of decoupled light 107. The smallest angle for which a high intensity I is measured corresponds to the critical angle of the total reflection, which is linked to the refractive index. The position on detector 108 that corresponds to the critical angle is marked by reference numeral 116.
[0053] FIG. 4a and associated FIG. 4b illustrate the propagation of the three light beams (cf. FIG. 3a) through cover panel 16, a contaminant 110 being situated on a surface of cover panel 16. Due to the presence of contaminant 110, the critical angle at which total reflection is possible inside cover panel 16 changes at the position of contaminant 110, so that the conditions necessary for the total reflection are met for only one of the three light beams of light 105 to be coupled in. Accordingly, only one of the three depicted light beams in the form of decoupled light 107 reaches detector 108. Similarly, the associated diagram of FIG. 4b shows a high intensity I for only one of the three light beams.
[0054] FIG. 5a and associated FIG. 5b show the same situation as in FIGS. 4a and 4b, but for a second contaminant 110′ that has a different refractive index. The refractive index of second contaminant 110′ does not allow a total reflection inside cover panel 16 for any of the three depicted light beams of light 105 to be coupled in, so that of the three depicted light beams, none reach detector 108. Correspondingly, the diagram of intensity I of the light ascertained by detector 108 from FIG. 5b no longer indicates an appreciable intensity I for any of the three depicted light beams. The position on detector 108 that corresponds to the critical angle is once again marked by reference numeral 116.
[0055] In the cases illustrated in FIGS. 3a, 4a, and 5a, detector 108 may be designed as a single-line CCD, for example, so that detector 108 may ascertain intensity I of the particular incident light along one spatial dimension for a plurality of pixels. Alternatively, as indicated in FIG. 2, for example, it is possible to design detector 108 in the form of multiple detector elements 109, each of which represents a photodiode, for example, that is sensitive to light. Each of these photodiodes may then correspondingly ascertain light for a certain angular range for which total reflection inside cover panel 16 is possible.
[0056] FIG. 6 shows one exemplary embodiment of a detection device 100 in conjunction with a cover panel 16 designed in the form of a circular cylinder having a cylinder axis 120. In this example, detection device 100 includes an emitter 102, and a detector 108 that includes two detector elements 109. Each of the two detector elements 109 may detect light that has been coupled into cover panel 16 over a certain angular range.
[0057] To cover the entire circumferential surface of cover panel 16 using detection device 100, emitter 102 and detector 108 are configured in such a way that they may rotate about cylinder axis 120. Due to rotation about cylinder axis 120, a light path 122 between emitter 102 and detector 108 steadily sweeps across the entire circumferential surface of circular cylindrical cover panel 16.
[0058] The specific embodiment of detection device 100 illustrated in FIG. 6 is suitable in particular in conjunction with sensor elements 12 that are designed as a LIDAR sensor and that likewise rotate about an axis.
[0059] The present invention is not limited to the exemplary embodiments described here and the aspects highlighted therein. Rather, numerous modifications are possible which are within the scope of activities carried out by those skilled in the art, in view of the disclosure herein.
