Apparatus and method for detecting the presence of water on a remote surface

• US 8,796,627 B2
• Filed: 12/07/2011
• Issued: 08/05/2014
• Est. Priority Date: 12/07/2010
• Status: Active Grant

• Current Assignee: Techwell Consulting LLC
• Original Assignee: Techwell Consulting LLC
• Inventors: Rockwell, Thomas L., Roddy, James E.
• Primary Examiner(s): HANNAHER, CONSTANTINE
• Application Number:
  US13/314,143
• Publication Number:
  US 20120140233A1
• Time in Patent Office: 972 Days
• Field of Search: 340/619, 340/605, 340/604, 340/603, 340/583, 250/341.8
• US Class Current: 250/341.8
• CPC Class Codes: G01N 21/4738 Diffuse reflection precedence is given to G01N21/55 - G01N21/57 if specular component is taken into consideration, e.g. also for testing fluids, fibrous materials
• CPC Class Codes: G01N 21/55 Specular reflectivity

Abstract

An apparatus is provided having a source for illuminating a remote surface with at least one wavelength of light (e.g., in the range of 940 to 970 nm), a detector for receiving returned illumination from the surface and providing an analog signal representative of the returned illumination, and a controller which samples the analog signal to obtain sample data representative of amplitude of light of the source returned from the surface by the detector. The controller determines the presence of water (or moisture, liquid, ice, vapor or heavy gases) on the surface in accordance with the sample data. An audible alarm is activatable by the controller. The source and detector are in a housing in perpendicular or non-perpendicular orientations with respect to the surface. Such housing being mountable at a distance from the surface where water detection is desired.

Claims

1. An apparatus for detecting a substance upon a surface comprising:

a source configured to illuminate a surface with at least one wavelength of light, wherein the source is configured to be driven at an oscillation frequency to modulate the illumination from the source;

a receiver configured to receive returned illumination from the surface;

a synchronous detector that provides a signal representative of the received returned illumination in accordance with the oscillation frequency that modulated the source; and

a controller configured to sample the signal at a time in accordance with the oscillation frequency to minimize the effect of any ambient light received by the synchronous detector in the signal to obtain sample data representative of amplitude of light of the source returned from the surface, and the controller determines the presence of the substance, on the surface in accordance with the sample data.

2. The apparatus according to claim 1 wherein the oscillation frequency has alternating peaks of a different sign (+ and −

), and the controller determines each time the signal corresponds to when the source was driven at the peaks and samples the signal at each of the times to obtain the sample data representative of the amplitude of the signal.

3. The apparatus according to claim 2 wherein the sample data for each sample of the signal represents an absolute value of the difference of the amplitude of the signal when sampled and the amplitude of the signal when previously sampled.

4. The apparatus according to claim 1 further comprising a quadrature detector configured to determine the difference in phase between the oscillation frequency of the source and the detected oscillation frequency of the return signal, and the sampling by the controller detector is offset by the difference in phase.

5. The apparatus according to claim 4 wherein the quadrature detector is part of the controller.

6. The apparatus according to claim 1 wherein the controller determines the presence of the substance in accordance with the sample data having a representative value in a period of time below a first threshold value, and the controller determines a fault condition in accordance with the sample data having a representative value in a period of time above a second threshold value, in which the fault condition prevents detection of the substance by the controller.

7. The apparatus according to claim 6 further comprising memory, wherein the controller stores sample data in the memory, and determines the presence of the substance in accordance with an average value of a plurality of the sample data stored in said memory over a period of time being below the first threshold to avoid false detection of the substance by the controller.

8. The apparatus according to claim 6 wherein the illumination is projected by the source along a first direction to illuminate a first region along the surface, and the receiver receives returned illumination along a second direction from a second region along the surface, in which the first region and the second region are the same or substantially overlap along the surface and wherein the first and second thresholds are set by the controller in accordance with sample data when the first region and second region along the surface is dry.

9. The apparatus according to claim 1 wherein the source is an LED operative at a wavelength in a range of 940 nm to 970 nm.

10. The apparatus according to claim 1 wherein the receiver comprises a phototransistor, photodiode, an avalanche photodiode, a photomultiplier, or LED for use as an illumination receiving element for detecting the returned illumination.

11. The apparatus according to claim 1 further comprising an audible alarm which is activated by the controller when the controller determines the presence of the substance on the surface.

12. The apparatus according to claim 1 wherein the controller is configured to control the operation of the source, the controller operates in at least a measurement mode and a sleep mode, the source is enabled by the controller in the measurement mode, the source is disabled by the controller in the sleep mode, and the controller alternates between the measurement mode and sleep mode.

13. The apparatus according to claim 12 wherein the controller operates in the sleep mode for a first period of time, and when the controller determines the presence of the substance in accordance with the sample data during the measurement mode the controller operates in the sleep mode for a second period to time shorter than the first period of time to increase the rate the controller alternates between the measurement mode and sleep mode.

14. The apparatus according to claim 13 wherein after a certain number of alternating periods of the measurement mode and the sleep mode at the increased rate the controller has determined the presence of the substance in accordance with the sample data, the controller activates an alarm indicative of the presence of the substance on the surface, otherwise the controller reset the sleep mode to the first period of time.

15. The apparatus according to claim 1 further comprising first optics for directing the illumination from the source to the surface.

16. The apparatus according to claim 15 wherein the first optics comprise one or more of a parabolic reflector, a lens, or a filter.

17. The apparatus according to claim 15 wherein the first optics comprises one or more of a glass lens, a molded plastic lens, a Fresnel lens, a cylinder lens, or a prism.

18. The apparatus according to claim 15 wherein the first optics comprises one or more cylinder lenses or prisms for forming a line beam on the surface.

19. The apparatus according to claim 15 further comprising second optics for collecting return light from the surface to the detector, and the second optics are identical to the first optics.

20. The apparatus according to claim 1 further comprising one or more optical elements for filtering illumination from one or more of the source and the detector.

21. The apparatus according to claim 1 wherein the source represents a plurality of sources each providing illumination at the same or different wavelengths.

22. The apparatus according to claim 21 wherein the sources are at different angles with respect to each other.

23. The apparatus according to claim 1 wherein the source represents a plurality of sources of a plurality of different wavelengths, and the synchronous detector providing the signal which is sampled by the controller to provide sample data for each one of the plurality of wavelengths.

24. The apparatus according to claim 23 wherein the controller determines a ratio of two values each representative of sample data associated with a different one of the plurality of wavelengths to determine the condition and type of fluid on the surface.

25. The apparatus according to claim 1 further comprising:

a housing for at least the source, the detector, and the controller, the housing is at a distance from the surface;

the illumination is projected by the source from the housing along a first direction to illuminate a first region along the surface, and the detector receives return illumination at the housing along a second direction from a second region along the surface, in which the first region and the second region are the same or substantially overlap along the surface; and

the synchronous detector is operable to provide the signal enabling the controller to obtain the sample data for use in determining the presence of the substance on the surface when the first direction and the second direction are each perpendicular with respect to the surface and when the first direction and the second direction are each non-perpendicular with respect to the surface.

26. The apparatus according to claim 25 wherein the surface represents a first surface, and the housing is mounted on a second surface at the distance from the first surface.

27. The apparatus according to claim 26 wherein the first surface represents the surface of a floor of a building or room, and the second surface represents the wall or ceiling of the building, room, or basement.

28. The apparatus according to claim 25 further comprising a visible LED or visible laser pointer used to align the first direction and second direction at a location on the surface.

29. The apparatus according to claim 1 wherein the substance comprises moisture, liquid, ice, vapor or heavy gases.

30. A method for detecting of a substance on a surface comprising:

illuminating a surface with at least one wavelength of light along a first direction to the surface in which the source is driven at an oscillation frequency;

receiving at a receiver returned illumination from the surface;

providing with a synchronous detector and in accordance with the oscillation frequency a signal representative of the received returned illumination; and

sampling by a controller the signal at a time in accordance with the oscillation frequency to minimize the effect of any ambient light received by the synchronous detector to obtain sample data representative of amplitude of light of the source returned from the surface; and

determining the presence of the substance in accordance with the sample data.

31. The method according to claim 30 further comprises providing an alarm signal when the presence of the substance is determined.

32. The method according to claim 30 wherein the determining step further comprising:

determining in accordance with a first threshold when the sample data indicates the presence of the substance; and

determining in accordance with a second threshold when the apparatus is in a condition preventing detection of the substance.

33. The method according to claim 30 wherein the illuminating further comprises providing illumination in the range of 940 to 970 nm.

34. The method according to claim 30 wherein the substance comprises moisture, liquid, ice, vapor or heavy gases.

35. An apparatus for detecting a substance upon a surface comprising:

a source configured to illuminate the surface with at least one wavelength of light, wherein the source is configured to be driven at an oscillation frequency to modulate the illumination from the source;

a receiver configured to receive returned illumination from the surface illuminated by the source;

a synchronous detector that provides a signal representative of the received returned illumination in accordance with the oscillation frequency that modulated the source; and

a controller configured to sample the signal at a time in accordance with the oscillation frequency to minimize the effect of any ambient light to obtain sample data representative of amplitude of light of the source returned from the surface, and determines in accordance with a first threshold when the sample data indicates the presence of the substance, and determines in accordance with a second threshold when the sample data indicates a fault condition preventing detection of the substance.

36. The apparatus according to claim 35 wherein the substance comprises moisture, liquid, ice, vapor or heavy gases.

37. An apparatus for detecting a substance upon a surface comprising:

a source configured to illuminate the surface with at least one wavelength of light in which the source is driven at an oscillation frequency to modulate the illumination from the source;

a receiver configured to receive returned illumination from the surface;

a synchronous detector that provides a signal representative of the received returned illumination in accordance with the oscillation frequency that modulated the source; and

a controller configured to sample the signal at a time in accordance with the oscillation frequency to minimize the effect of any ambient light received to obtain sample data representative of amplitude of light of the source returned from the surface in which the time of capture of each sample of the signal by the controller is in accordance with the synchronous detector aligned with the peaks of the oscillation frequency by a quadrature detector to diminish effect of any ambient light present in the signal; and

the controller determines the presence of the substance in accordance with the sample data.

38. The apparatus according to claim 37 wherein the substance comprises moisture, liquid, ice, vapor or heavy gases.

39. An apparatus for detecting the substance upon a surface comprising:

a source configured to illuminate the surface with at least one wavelength of light wherein the source is configured to be driven at an oscillation frequency to modulate the illumination from the source;

a receiver configured to receive returned illumination from the surface;

a synchronous detector that provides a signal representative of the received returned illumination in accordance with the oscillation frequency that modulated the source; and

a controller configured to sample the signal at a time in accordance with the oscillation frequency to minimize the effect of any ambient light received to obtain sample data representative of amplitude of light of the source returned from the surface; and

the controller controls the operation of the source and the synchronous detector, the controller operates in at least a measurement mode and a sleep mode, the source is enabled by the controller in the measurement mode for a first period of time, the source is disabled by the controller in the sleep mode for a second period of time, the controller alternates between the measurement mode and sleep modes, the first time period is less than the second time period, and the second period of time is automatically adjusted to increase the frequency of the controller in the measurement mode upon controller determination of possible the substance in accordance with the sample data in order to verify the presence of the substance on the surface.

40. The apparatus according to claim 39 wherein the substance comprises moisture, liquid, ice, vapor or heavy gases.