Moisture meter with impedance and relative humidity measurements

• US 6,553,813 B2
• Filed: 02/28/2001
• Issued: 04/29/2003
• Est. Priority Date: 02/29/2000
• Status: Active Grant

• Current Assignee: Rynhart Research Limited
• Original Assignee: Rynhart Research Limited
• Inventors: McIlroy, James, Fallon, John, Rynhart, Alan
• Primary Examiner(s): Larkin, Daniel S.
• Assistant Examiner(s): Frank, Rodney
• Application Number:
  US09/794,007
• Publication Number:
  US 20010017053A1
• Time in Patent Office: 790 Days
• Field of Search: 73/73, 73/74, 738/665, 734/31, 73/290.1
• US Class Current: 73/73
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825

Abstract

A moisture meter (1) has a hand-held casing (2) with a digital microcontroller (50), LCD display (4), and a keypad (3). Spring-loaded contacts (6) contact material and allow capacitive impedance measurement via electrodes (5) and drive/pickup circuits (20). Also, a relative humidity probe (9) provides an input so that the processor generates both moisture contact near-surface measurements and also relative humidity measurements. This allows optimum analysis of material.

Claims

1. A moisture meter comprising:

a hand-held housing;

a controller;

an input interface;

an output interface;

an electrical impedance sensor connected to the controller;

a relative humidity probe connected to the controller; and

means in the controller for processing signals from the impedance sensor to generate a moisture content output, and for processing signals from the relative humidity probe to generate a relative humidity output.

2. The moisture meter as claimed in claim 1, wherein the controller comprises means for storing material parameter datasets for each of a plurality of materials, means for allowing user selection of a relevant dataset, and means for processing input signals according to the selected dataset.

3. The moisture meter as claimed in claim 2, wherein the controller comprises means for storing a dataset for each of concrete and gypsum.

4. The moisture meter as claimed in claim 3, wherein the controller comprises means for storing a dataset for each of a plurality of concrete and gypsum types.

5. The moisture meter as claimed in claim 1, wherein the relative humidity probe further comprises a temperature sensor and the controller includes means for processing input signals from said sensor and for generating a temperature output.

6. The moisture meter as claimed in claim 1, wherein the impedance sensor includes capacitive electrodes connected to associated drive and pick-up circuits.

7. The moisture meter as claimed in claim 6, wherein each electrode comprises a plurality of spring-loaded contacts for uniform contact with material.

8. The moisture meter as claimed in claim 7, wherein a drive frequency is approximately 125 kHz.

9. The moisture meter as claimed in claim 1, wherein the controller comprises means for storing a data record for each measurement of the impedance sensor and of the relative humidity probe.

10. The moisture meter as claimed in claim 9, wherein the relative humidity probe further comprises a temperature sensor and the controller includes means for writing temperature data to a relative humidity data record.

11. The moisture meter as claimed in claim 1, wherein the relative humidity probe comprises a capacitive sensor, a pulse width modulator for modulating output of the capacitive sensor and an averaging filter for averaging the modulated signal.

12. The moisture meter as claimed in claim 11, wherein the probe further comprises a digital microcontroller connected to receive an output from the averaging filter via an analog to digital converter.

13. The moisture meter as claimed in claim 1, wherein the probe comprises a housing of tubular shape including openings at an inner end for access by air to internal sensing components.

14. The moisture meter as claimed in claim 13, wherein the probe housing is of castellated shape at its inner end.

15. The moisture meter is claimed in claim 13, wherein the probe further comprises a grommet including means for sealing around the probe at the mouth of a bore.

16. The moisture meter as claimed in claim 13, wherein the probe further comprises a sleeve including means for receiving the probe body when inserted in a bore.

17. The moisture meter as claimed in claim 16, further comprising a grommet including means for sealing around the probe at a mouth of a bore, wherein the sleeve is a friction fit within the grommet.