SENSOR FOR MEASURING HIGH HUMIDITY CONDITIONS AND/OR CONDENSATION

• US 20140026652A1
• Filed: 07/25/2012
• Published: 01/30/2014
• Est. Priority Date: 07/25/2012
• Status: Abandoned Application

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: O'Connell, John O., Cummins, Timothy
• Application Number:
  US13/557,739
• Publication Number:
  US 20140026652A1
• Time in Patent Office: Days
• US Class Current: 73/335.04
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825

Abstract

A humidity sensor is provided having humidity levels approaching 100% relative humidity can be measured, as well as condensation measurements which appear as RH values “above 100%”. The humidity sensor is a capacitance based sensor. The capacitor(s) of the sensor is dimensioned so that substantial electric fields of the capacitor extend to the sensor/ambient air interface so that the conditions at the ambient side of the interface provide data for the sensor. In particular, the capacitance effects of moisture formation on the ambient side of the sensor/ambient air interface are utilized as part of the measurements so that relative humidity levels below and above 100% can be detected. The capacitor(s) of the sensor is dimensioned so that substantial electric fields of the capacitor extend to the air interface so that the conditions at ambient side of the interface provide data for the sensor.

Claims

1. A humidity sensor comprising:

a humidity sensitive dielectric material having a surface that may be exposed to ambient air conditions; and

a plurality of capacitor electrodes, the capacitive electrodes formed such that capacitive measurements of the humidity sensitive dielectric material may be obtained, the capacitive measurements being indicative of the humidity levels of the ambient air conditions;

the plurality of capacitor electrodes configured to provide electric fields between the capacitor electrodes, at least some of the electric fields extending beyond a surface of the humidity sensitive dielectric material that is exposed to ambient air conditions such that relative humidity levels of less than 95% may be detected from moisture that ingresses into the humidity sensitive dielectric material and relative humidity levels of greater than 100% may be indicated as a result of the at least some of the electric fields extending beyond the surface of the humidity sensitive dielectric material, the detection of relative humidity levels in excess of 100% being indicative of condensate forming on the humidity sensor.

2. The humidity sensor of claim 1, wherein the capacitor electrodes are spaced such that at least 5% of the electric fields between the capacitor electrodes extend beyond the surface of the humidity sensitive material that is exposed to the ambient air condition.

3. The humidity sensor of claim 2, wherein the capacitor electrodes are spaced such that between 5% and 20% of the electric fields between the capacitor electrodes extend beyond the surface of the humidity sensitive material that is exposed to the ambient air condition.

4. The humidity sensor of claim 1, wherein the humidity sensor detects differing amounts of condensate on the humidity sensitive dielectric material surface.

5. The humidity sensor of claim 4, wherein the differing amounts of condensate include at least fogging and the formation of a continuous water sheet.

6. The humidity sensor of claim 1, wherein the humidity sensor provides continuous detection of relative humidity levels from below 90% relative humidity to relative humidity levels above 100%.

7. The humidity sensor of claim 6, wherein the capacitor electrodes are spaced such that between 5% and 20% of the electric fields between the capacitor electrodes extend beyond the surface of the humidity sensitive material that is exposed to the ambient air condition.

8. The humidity sensor of claim 1, the humidity sensitive dielectric material overlaying the plurality of capacitor electrodes.

9. The humidity sensor of claim 1, the humidity sensor providing a continuum of humidity measurements from measurement levels less than 100% relative humidity to levels greater than 100%.

10. The humidity sensor of claim 9, the humidity sensor providing capacitive measurements having a measurement transition indicative of the formation of a continuous film of water on the humidity sensitive dielectric material surface.

11. The humidity sensor of claim 1, the humidity sensor providing capacitive measurements having a measurement transition indicative of the formation of a continuous film of water on the humidity sensitive dielectric material surface.

12. A method of configuring a humidity sensor, comprising:

providing a humidity sensitive material that may be exposed to an ambient air condition;

providing electrodes that may be configured to be used in the electrical detection of the ingress of moisture into the humidity sensitive material, the electrical detection providing for detection of humidity levels at least below 95% relative humidity levels in the ambient air condition; and

configuring the humidity sensor to detect relative humidity levels of greater than 100%, the detection of relative humidity levels in excess of 100% being indicative of condensate forming on the humidity sensor.

13. The method of claim 12, wherein the differing amounts of condensate include at least fogging and the formation of a continuous water sheet.

14. The method of claim 12, wherein the electrodes are capacitor electrodes and the humidity levels both above and below 100% are detected by monitoring capacitive changes between the electrodes.

15. The method of claim 14, wherein the capacitor electrodes are formed so that substantial electric fields of the capacitor electrodes extend beyond a surface of the humidity sensitive material that is exposed to the ambient air condition.

16. The method of claim 14, wherein at least 5% of the electric field between the capacitor electrodes extend beyond the surface of the humidity sensitive material that is exposed to the ambient air condition.

17. The method of claim 16, wherein between 5% and 20% of the electric field between the capacitor electrodes extend beyond the surface of the humidity sensitive material that is exposed to the ambient air condition.

18. The method of claim 17, wherein the differing amounts of condensate comprise of at least fogging and the formation of a continuous water sheet.

19. The method of claim 14, wherein the differing amounts of condensate comprise of at least fogging and the formation of a continuous water sheet.

20. The method of claim 12, wherein the humidity sensor provides continuous detection of relative humidity levels from below 90% relative humidity to relative humidity levels above 100%.

21. The method of claim 12, wherein the humidity sensitive material is a dielectric.

22. The method of claim 21, wherein the electrodes are capacitor electrodes and at least 20% of the electric fields between the capacitor electrodes extend beyond the surface of the humidity sensitive material that is exposed to the ambient air condition.

23. The method of claim 21, wherein the electrodes are capacitor electrodes and between 5% and 20% of the electric fields between the capacitor electrodes extend beyond the surface of the humidity sensitive material that is exposed to the ambient air condition.

24. The method of claim 21, wherein the electrodes are capacitor electrodes, the capacitor electrodes being configured to be utilized for detection of relative humidity levels both above and below 100% relative humidity.

25. The method of claim 12, further comprising providing a continuum of humidity measurements from measurement levels less than 100% relative humidity to levels greater than 100%.

26. The method of claim 25, further comprising providing capacitive measurements having a measurement transition indicative of the formation of a continuous film of water on the humidity sensitive dielectric material surface.

27. The method of claim 12, further comprising providing capacitive measurements having a measurement transition indicative of the formation of a continuous film of water on the humidity sensitive dielectric material surface.