Capacitance-based moisture sensor and controller

• US 20060144438A1
• Filed: 03/31/2005
• Published: 07/06/2006
• Est. Priority Date: 12/29/2004
• Status: Active Grant

• Current Assignee: Rain Bird Corporation
• Original Assignee: Rain Bird Corporation
• Inventors: Dresselhaus, Daniel D., O'Brien, Kevin G.
• Granted Patent: US 7,836,910 B2
• Time in Patent Office: Days
• US Class Current: 137/78.300
• CPC Class Codes: F16K 37/0091 by measuring fluid parameters
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01N 33/246 for water content for control of watering A01G25/167
• CPC Class Codes: Y10T 137/189 Soil moisture sensing

Abstract

Moisture sensor devices and methods associated with operation of the moisture sensor devices are disclosed herein. One embodiment includes a moisture sensor and controller device adapted to be placed in soil comprising a switch adapted to be coupled to a power control line of an irrigation controller, the power control line for sending an activating power signal to an irrigation valve; a control circuit coupled to the switch; and a sensor circuit coupled to the control circuit and adapted to provide a signal to the control circuit, the signal corresponding to a moisture level of the soil; wherein the control circuit is adapted to control the switch to interrupt the activating power signal based on the signal from the sensor circuit; wherein the switch and the control circuit are both external to the irrigation controller.

Claims

1. A moisture sensor and controller device adapted to be placed in soil comprising:

a switch adapted to be coupled to a power control line of an irrigation controller, the power control line for sending an activating power signal to an irrigation valve;

a control circuit coupled to the switch; and

a sensor circuit coupled to the control circuit and adapted to provide a signal to the control circuit, the signal corresponding to a moisture level of the soil;

wherein the control circuit is adapted to control the switch to interrupt the activating power signal based on the signal from the sensor circuit;

wherein the switch and the control circuit are both external to the irrigation controller.

2. The moisture sensor and controller device of claim 1 further comprising a circuit board attached to the switch, the control circuit and the sensor circuit.

3. The moisture sensor and controller device of claim 1 further comprising a water tight housing enclosing the switch and the control circuit.

4. The moisture sensor and controller device of claim 3 wherein the water tight housing includes a cap enclosing the switch and the control circuit.

5. The moisture sensor and controller device of claim 3 wherein the water tight housing encloses the sensor circuit.

6. The moisture sensor and controller device of claim 3 wherein the water tight housing includes a coating material formed over the circuit board.

7. The moisture sensor and controller device of claim 4 wherein the cap is filled with a potting material.

8. The moisture sensor and controller device of claim 4 further comprising an end cap rigidly affixed to the circuit board.

9. The moisture sensor and controller device of claim 3 further comprising a plurality of electrical connectors extending from the water tight housing.

10. The moisture sensor and controller device of claim 2 wherein the circuit board is a multi-layered circuit board and wherein the sensor circuit includes electrodes formed on an inner layer of the multi-layered circuit board.

11. The moisture sensor and controller device of claim 1 wherein the switch, the control circuit, and the sensor circuit are integrated into a single device.

12. An integrated moisture sensor and controller device adapted to be placed in soil comprising:

a controller circuit for controlling actuation of a valve; and

a sensor circuit coupled to the controller circuit, the sensor circuit adapted to provide the controller circuit a signal corresponding to a moisture level of the soil;

wherein the controller circuit and the sensor circuit are integrated into a single device.

13. The integrated moisture sensor and controller device of claim 12 further comprising a housing enclosing the controller circuit.

14. The integrated moisture sensor and controller device of claim 13 further comprising:

a circuit board at least partially within the housing;

wherein the sensor is formed on the circuit board, the sensor including two electrodes forming a capacitor, a capacitance of a capacitor varies as a function of a moisture content of soil;

wherein the controller circuit is attached to the circuit board;

wherein the housing comprises a waterproof housing adapted to prevent water from the soil from contacting the controller circuit.

15. The integrated moisture sensor and controller device of claim 13 further comprising a circuit board at least partially within the housing, wherein the controller circuit and the sensor circuit are attached to the circuit board.

16. The integrated moisture sensor and controller device of claim 13 further comprising a circuit board including a trace pattern formed on the circuit board, the trace pattern forming two electrodes of a capacitor, a capacitance of the capacitor varies as a function of a moisture content of soil.

17. The integrated moisture sensor and controller device of claim 16 wherein the circuit board is a multi-layer circuit board and wherein the trace pattern is formed on an inner layer of the multi-layer circuit board.

18. The integrated moisture sensor and controller device of claim 16 further comprising an insulating layer formed over the printed circuit board to seal the printed circuit board from the soil.

19. The integrated moisture sensor and controller device of claim 18 wherein the insulating layer comprises a coating formed around the printed circuit board.

20. The integrated moisture sensor and controller device of claim 18 wherein the insulating layer comprises a plastic sleeve formed around the printed circuit board.

21. The integrated moisture sensor and controller device of claim 13 wherein the housing comprises a waterproof housing enclosing the controller circuit.

22. The integrated moisture sensor and controller device of claim 13 wherein the controller circuit further comprises:

a variable frequency oscillator, a frequency of the variable frequency oscillator varies a function of the capacitance of a capacitor within the sensor circuit, the capacitance varies as a function of the moisture content of the soil;

a reference oscillator; and

a logic circuit for comparing a frequency of the variable frequency oscillator to a frequency of the reference oscillator.

23. The integrated moisture sensor and controller device of claim 13 further comprising a logic power supply for providing power to the controller circuit and a switch.

24. The integrated moisture sensor and controller device of claim 13 wherein the controller further comprises a logic circuit for communicating with a remote device.

25. The integrated moisture sensor and controller device of claim 24 wherein the logic circuit for communicating with a remote device includes means for detecting a power interrupt on a power line.

26. An integrated moisture sensor and controller comprising:

a housing adapted to be positioned in soil;

a sensor coupled to the housing, the sensor adapted to measure a moisture level in the soil; and

a control circuit coupled to the sensor, the control circuit contained within the housing and adapted to store a savings value corresponding to an amount of water savings, wherein the sensor and the controller are integrated into a single device.

27. The integrated moisture sensor and controller of claim 26 further comprising a communication circuit for sending a signal corresponding to the savings value to an electronic device.

28. The integrated moisture sensor and controller of claim 26 wherein the electronic device is an irrigation controller.

29. The integrated moisture sensor and controller of claim 26 wherein the electronic device is a remote test tool.

30. The integrated moisture sensor and controller of claim 26 wherein the saving value corresponding to an amount of water savings comprises a percentage water savings calculated by the controller.

31. A moisture sensor unit for use in soil comprising:

a probe adapted to be inserted into the soil, wherein the probe is adapted to be responsive to a moisture level in the soil; and

a first protrusion coupled to the probe and adapted to maintain the probe in a desired orientation within the soil.

32. The moisture sensor unit of claim 31 further comprising a control circuit coupled to the probe, the control circuit adapted to receive a signal from the probe, the control circuit further adapted to control activation of a valve.

33. The moisture sensor unit of claim 32 further comprising a cap formed around the control circuit.

34. The moisture sensor unit of claim 32 further comprising a circuit board, wherein the probe and the control circuit are formed on the circuit board.

35. The moisture sensor unit of claim 33 further comprising an end cap coupled to the probe.

36. The moisture sensor unit of claim 35 further comprising a second protrusion extending from the end cap and adapted to maintain the probe in a desired orientation within the soil, wherein the first protrusion extends from the cap formed around the control circuit.

37. The moisture sensor unit of claim 34 wherein the circuit board comprises a multi-layered circuit board.

38. The moisture sensor unit of claim 31 further comprising a coating formed around the probe.

39. The moisture sensor unit of claim 31 further comprising a plastic sleeve formed around the probe.