METHOD FOR FOG DETECTION FOR A VEHICLE WITH A FOG DETECTOR WITH A SPECIALLY SHAPED LENS

Abstract

The present invention refers to a fog detector for a vehicle, with a specially shaped lens, comprising: a light emitter (1) configured to emit at least one light pulse; a first optical element (2) configured to direct light of the at least one light pulse along a first optical path; a second optical element (4) configured to direct scattered light of the at least one light pulse along a second optical path to a focal spot of a light receiver (3) of the fog detector, wherein the focal spot is spatially offset from an axis extending along the first optical path; the first optical element (2) and the second optical element (4) being arranged and constructed such that the first and the second optical path at least partially overlap with each other and the first optical element (2) and the second optical element (4) being arranged and constructed such that the light emitter (1) and the light receiver (3) are operable on a common optical axis.

The present invention also refers to a method for fog detection and a driving support system comprising the fog detector. Furthermore, the present invention refers to a vehicle comprising the driving support system. Furthermore, the present invention refers to a computer program, a data carrier signal, and a computer-readable medium.

Claims

1. A fog detector for a vehicle, with a specially shaped lens, comprising: a light emitter configured to emit at least one light pulse; a first optical element configured to direct light of the at least one light pulse along a first optical path; a second optical element configured to direct scattered light of the at least one light pulse along a second optical path to a focal spot of a light receiver of the fog detector, wherein the focal spot is spatially offset from an axis extending along the first optical path; the first optical element and the second optical element being arranged and constructed such that the first and the second optical path at least partially overlap with each other, and the first optical element and the second optical element being arranged and constructed such that the light emitter and the light receiver are operable on a common optical axis.

2. The fog detector according to claim 1, wherein the light receiver is configured to produce at least one electronic noise signal based on received scattered light.

3. The fog detector according to claim 1, further comprising a noise analyzer configured to analyze a form of the at least one electronic noise signal.

4. The fog detector according to claim 1, wherein the first optical element and the second optical element are constructed as one piece.

5. The fog detector according to claim 1, wherein the first optical path corresponds to a centered optical path of the light emitter and the second optical path is decentered to the optical path of the light emitter.

6. The fog detector according to claim 1, wherein the first optical element and the second optical element are constructed and arranged such that they have a common optical axis.

7. The fog detector according to claim 1, wherein the first optical element comprises a collimating lens and the second optical element comprises a focusing lens.

8. The fog detector according to claim 1, wherein the second optical element comprises a prism-shaped lens part.

9. The fog detector according to claim 1, wherein the first and/or the second optical element is/are arranged and constructed such that the decentered light receiver receives backscattered, focused light reflected by a target placed in far-field.

10. The fog detector according to claim 1, wherein the light emitter and the light receiver are constructed and/or arranged separately from each other.

11. The fog detector according to claim 1, wherein the first and/or the second optical element at least partially comprises a design which is constructed according to a freeform optic design.

12. A driving support system comprising the fog detector according to claim 1.

13. A vehicle comprising the driving support system according to claim 12.

14.-17. (canceled)

Description

[0036] In the drawings:

[0037] FIG. 1 shows a flow chart of a method according to the invention,

[0038] FIG. 2 shows a schematic view of an embodiment of an arrangement of optical elements according to the invention,

[0039] FIG. 3 shows another schematic view of the embodiment of the arrangement of the optical elements according to the invention,

[0040] FIG. 4 shows a schematic view of a first embodiment of a second optical element,

[0041] FIG. 5 shows a schematic view of a second embodiment of the second optical element,

[0042] FIG. 6 shows another schematic view of the second embodiment of the second optical element, FIG. 7 shows another schematic view of the second embodiment of the second optical element and

[0043] FIG. 8 shows a schematic view of an embodiment of a first optical element.

[0044] FIG. 1 shows a flow chart of a method according to the invention.

[0045] The method is appropriate for fog detection for a vehicle and is carried out with a fog detector with a specially shaped lens, and with a vehicle-integrated driving support system for executing at least one step of the method.

[0046] According to step “100”, the method comprises emitting at least one light pulse, by a light emitter 1 of the fog detector, and directing light of the at least one light pulse, via a first optical element 2, along a first optical path.

[0047] According to step “200”, the method comprises directing scattered light of the at least one light pulse along a second optical path to a focal spot of a light receiver 3 of the fog detector, via a second optical element 4. The focal spot is spatially offset from an axis extending along the first optical path.

[0048] The first optical element 2 and the second optical element 4 are arranged and constructed such that the first and the second optical path at least partially overlap with each other and the first optical element 2 and the second optical element 4 are arranged and constructed such that the light emitter 1 and the light receiver 3 are operable on a common optical axis.

[0049] According to step “300”, the method comprises producing at least one electronic noise signal based on received scattered light, by the light receiver 3. The method further comprises, according to a step “400”, analyzing, by a noise analyzer, a form of the at least one electronic noise signal.

[0050] In FIG. 2, a schematic view of a setup of the first optical element 2 and the second optical element 4 is shown. The first and the second optical element 2, 4 are made as one piece. In FIG. 3, a further view of this setup is shown. The principle is to merge two optical elements of transmitter and receiver in order to increase the range of detection of the fog by merging the in-air optical paths of the transmitted light of the received back-scattered light.

[0051] In FIG. 4, a first embodiment of the second optical element 4 is shown. The second optical element 4 comprises a focusing lens 7 and a prism-shaped part 8. The design for a receiver should be very simple while it is about focusing the backscattered light. In other words, the focal spot of the light receiver 3 is decentered in order to have place for both light emitter 1 and light receiver 3. To realize it, a prism-shaped part 8 is added on the backside of the lens.

[0052] In FIG. 5, a second embodiment of the second optical element 4 is shown. According to this embodiment, the second optical element 4 comprises, besides the parts described regarding the embodiment according to FIG. 4, parts which are configured with the aid of free-form optics. In FIGS. 6 and 7, other views of the optical element 4 according to FIG. 5 are depicted. FIG. 6 shows a front view of the second optical element 4 and FIG. 7 shows a rear view of the second optical element 4.

[0053] In FIG. 8, a possible embodiment of the first optical element 2 is shown. According to this embodiment, the first optical element 2 is a collimating lens 6. The transmitter optical element has to collimate the light at best in order to propagate the farer with the highest optical density. Such element can be designed as a traditional thick lens.

[0054] The previously described optical arrangements could be used for a fog detection system, which could be implemented in any transparent part of the body of the vehicle, such as the headlights or the windshield. Furthermore, it could be a complement of already existing product like the rain sensor.

[0055] The analysis of the optical signal can be done by measuring its intensity or by performing a time-of-flight measurement. In both case, the analysis is based on the optical noise which is backscattered to the surrounding part of the optical element. An increase of the optical noise would indicate an increase of the backscattered light. By analyzing the optical noise in intensity and/or in time domain it is then possible to identify the presence of fog and to discriminate it from the optical burst that would be generated by an eventual object which would have hard physical properties.

REFERENCE SIGNS LIST

[0056] 1 light emitter [0057] 2 first optical element [0058] 3 light receiver [0059] 4 second optical element [0060] 6 collimating lens [0061] 7 focusing lens [0062] 8 prism-shaped lens part [0063] 100 directing light of the at least one light pulse, via a first optical element, along a first optical path [0064] 200 directing scattered light of the at least one light pulse along a second optical path to a focal spot of a light receiver of the fog detector, via a second optical element, the focal spot being spatially offset from an axis extending along the first optical path, [0065] 300 producing at least one electronic noise signal based on received scattered light, by the light receiver [0066] 400 analyzing, by a noise analyzer, a form of the at least one electronic noise signal