Multi-mode rain sensor

• US 20080116379A1
• Filed: 09/14/2007
• Published: 05/22/2008
• Est. Priority Date: 11/16/2006
• Status: Active Grant

• Current Assignee: Pilkington North America, Inc.
• Original Assignee: Pilkington North America Incorporated (Pilkington PLC)
• Inventors: Teder, Rein S.
• Granted Patent: US 7,847,255 B2
• Time in Patent Office: Days
• US Class Current: 250/341.1
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0837 with a particular arrangement of the optical elements
• CPC Class Codes: G01N 21/552 Attenuated total reflection

Abstract

The present invention relates to a rain sensor that adaptively functions in a variety of different modes when deployed on vehicle windows of different thicknesses and compositions. The arrangement of multiple lens segments and reflecting surfaces in a nonsequential configuration allows utilization of a greater proportion of light rays from the at least two emitters. Further, a greater portion of the light rays emitted by the at least two emitters is captured by the lens segments and reflectors arranged about at least two detectors, and directed to the detectors. Connection to analytical circuitry then allows interpretation of electrical signals, which in turn control, for example, window wiper systems.

Claims

1. An optical rain sensor capable of efficiently detecting moisture on vehicle windows of varying thickness and infrared radiation transmission comprising:

an optical coupler into which optical elements are molded, wherein the optical elements comprise a plurality of lens segments for directing infrared rays, and further wherein, the optical coupler is mechanically and optically coupled to a major surface of a vehicle window having a thickness t, and infrared radiation transmittance Tir;

a housing detachably mounted to the coupler which housing holds a circuit board substantially parallel to the vehicle window;

electronic components mounted on the circuit board comprising at least two emitters of infrared radiation and at least two detectors of infrared radiation, each having an extent E;

the plurality of lens segments being molded into the optical coupler, proximate, and at a height above each of the at least two emitters and at least two detectors, whereby infrared rays emitted from the at least two emitters are collimated and then directed, nonsequentially, in one or more of at least four optical paths by the plurality of lens segments through the vehicle window and back to the at least two detectors, wherein the specific optical path followed by the infrared radiation is dependent on t and Tir, and the amount of infrared radiation captured by each of the two emitters and at least two detectors is equal to no less than E-80%.

2. The optical rain sensor defined in claim 1, wherein t=4.0-6.5 mm, Tir=17-75%, rays useful for sensing moisture are directed, primarily, by at least one:

on-axis collimator lens, above-emitter collimator lens, on-axis receiver lens and above-detector receiver lens, such that the emitter and detector extent utilized is equal to no less than E-60%.

3. The optical rain sensor defined in claim 1, wherein t=6.5-9.5 mm, Tir=20-70%, rays useful for sensing moisture are directed, primarily, by at least one:

above-emitter collimator lens and above-detector receiver lens, and emitter-side folder structure and on-axis receiver lens, as well as, on-axis collimator lens and receiver folder structure, such that the emitter and detector extent utilized is equal to no less than E-70%.

4. The optical rain sensor defined in claim 1, wherein t=9.5-12 mm, Tir=20-65%, rays useful for sensing moisture are directed, primarily, by at least one:

emitter-side folder structure and on-axis receiver lens, emitter-side folder structure and above-detector receiver lens, above-emitter lens and detector-side folder structure, as well as emitter-side folder structure and detector-side folder structure, such that the emitter and detector extent utilized is equal to no less than E-75%.

5. The optical rain sensor defined in claim 1, wherein t≦

4.0 mm, Tir >

70%, rays useful for sensing moisture are directed, primarily, by at least one;

on-axis collimator lens and on-axis receiver lens, above-emitter collimator lens and above-detector receiver lens, as well as one or more deflections off a center coupler region, such that the emitter and detector extent utilized is no less than E-60%.

6. The optical rain sensor defined in claim 1, wherein the optical elements are molded from the group consisting of acrylic and polycarbonate materials.

7. The optical rain sensor defined in claim 1, wherein the infrared rays are collimated by at least one on-axis collimator lens and at least one above-emitter collimator lens.

8. The optical rain sensor defined in claim 1, wherein the at least two emitters comprise a microprocessor which emit rays over a 180°

hemisphere.

9. The optical rain sensor defined in claim 1, wherein the at least two detectors comprise one chosen from the group consisting of:

a photodiode, a phototransistor, a photovoltaic cell, or a photo-resistor.

10. A moisture sensor for mounting on a first surface of a sheet of glass to detect moisture in a sensing area on a second surface of the sheet of glass, which second surface is parallel to the first surface, the moisture sensor comprising:

a) a coupler having a mounting surface and a multi-functional optical surface, mountable on a first surface of a sheet of glass for optically coupling light rays into and out of the glass sheet;

b) the multifunctional optical surface of the coupler further comprising;

two or more collimator lenses, for collimating light rays into two or more collimated light beams, and two or more folder lens structures for re-directing light rays and two or more focuser lens structures;

c) a housing detachably secured to the coupler;

d) a planar circuit board secured in the housing and having a device surface which is disposed substantially parallel to the first surface of the sheet of glass;

e) one or more emitters mounted on the device surface of the circuit board for emitting light rays about an emission axis, the one or more emitters in proximity to one or more collimator lenses, and one or more folder lens structures; and

f) one or more detectors mounted on the device surface of the circuit board for receiving light rays about a detection axis, and for generating electrical signals in response to the light detected, the one or more detectors in proximity to one or more focuser lens structures and one or more folder lens structures.

11. The moisture sensor defined in claim 10, wherein the multi-functional optical surface of the coupler is molded from one or more polymeric materials chosen from the group consisting of acrylic and polycarbonate materials.

12. The moisture sensor defined in claim 11, wherein the two or more collimator lenses each have an optical axis oriented at about 45 degrees with respect to the planar circuit board.

13. The moisture sensor defined in claim 12, wherein the collimator lenses in proximity to the at least one emitter comprise at least one on-axis collimator lens and at least one above-emitter collimator lens.

14. The moisture sensor defined in claim 13, wherein the folder lens structure in proximity to the at least one emitter comprises an emitter-side folder structure.

15. The moisture sensor defined in claim 14, wherein the emitter-side folder structure comprises a convex refracting surface in a plane parallel to the one or more emitters, and a planar reflecting surface substantially parallel to the first surface of the sheet of glass.

16. The moisture sensor defined in claim 12, wherein the collimator lenses in proximity to at the least one detector comprise at least one on-axis collimator lens and at least one above-detector collimator lens.

17. The moisture sensor defined in claim 16, wherein the folder lens structure in proximity to the at least one detector comprises a detector-side folder structure.

18. The moisture sensor defined in claim 10, wherein the optical axis of the at least one emitter, and the optical axis of the at least one detector are each at an orientation of about 45 degrees to the surface of the planar circuit board.

19. The moisture sensor defined in claim 10, wherein the light rays collimated by the two or more collimator lenses and re-directed, where necessary, by the emitter-side and detector-side folder structures are directed to a detection surface of the one or more detectors.