Electrical field sensors

• US 20070216424A1
• Filed: 03/15/2006
• Published: 09/20/2007
• Est. Priority Date: 03/15/2006
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Steffen, Michael, Sieh, Philip, Stewart, Bradley
• Granted Patent: US 7,432,725 B2
• Time in Patent Office: Days
• US Class Current: 324/662
• CPC Class Codes: G01F 23/268 mounting arrangements of probes
• CPC Class Codes: G01R 29/12 Measuring electrostatic fields or voltage-potential

Abstract

The present disclosure provides several systems. In general, it provides E-field sensor systems that utilize at least one electrode 100 adapted for creating an E-field in an area 210 within a detection volume where fluid presence 400 or presence of a solid body 300 is to be detected. The electrical field sensor is configured to generate a detected signal responsive to a change in capacitance of the electric field, and is communicatively coupled to the electrode 100. In addition, a processor 275 is configured to determine a quantitative measure of a fluid or solid body within the detection volume in accordance with a capacitive relationship with the detection volume. Described are examples of the system for fluid presence detection, fluid level measurement and measurement of proximity to a solid object.

Claims

1. An electric field sensor system comprising:

a first electrode adapted for creating an electric field in an area within a detection volume where fluid presence or level is to be detected;

a second electrode communicatively coupled to the first electrode;

an electrical field sensor communicatively coupled to the first electrode, the electrical field sensor configured to generate a detected signal responsive to a change in the electric field; and

a processor coupled to the field sensor, the processor configured to determine a quantitative measure of a fluid within the detection volume from the detected signal in accordance with a capacitive relationship between the first electrode, the detection volume and fluid properties;

wherein the first electrode and the second electrode are of complementary shape such that any equal length complementary segments have a constant area.

2. The system of claim 1, wherein the first electrode comprises a first series of discrete electrodes, the discrete electrodes arrayed to each create an E-field in an area in a vicinity of the electrode.

3. The system of claim 2, wherein the capacitive relationship comprises:

4. The system of claim 1, wherein the first electrode comprises a first continuous strip electrode or a series of ring electrodes or a series of strip electrodes.

5. The system of claim 4, wherein the first electrode is a substantially uniformly rectangular strip, and the ground plate or second electrode comprise dimensions substantially identical to the first electrode.

6. The system of claim 5, wherein the capacitive relationship comprises:

7. The system of claim 5, further comprising a pair of reference electrodes.

8. The system of claim 7, wherein the processor is further configured to determine a quantitative measure of fluid by including dimensional and capacitive relationships between the first electrode and the reference electrodes.

9. (canceled)

10. The system of claim 9, wherein the capacitive relationship comprises:

11. The system of claim 10, wherein inputs to the processor comprise a relationship between fluid quantitative measure, capacitance and a ratio of an area A₁ of the first electrode to an area A₂ of the second electrode.

12. An electric field sensor system comprising:

a series of discrete first electrodes, each adapted for creating an electric field within a local detection volume wherein fluid presence or level is to be detected;

an electrical field sensor communicatively coupled to the first electrodes, the electrical field sensor configured to generate a detected signal responsive to a change in the electric field; and

a processor coupled to the electrical field sensor, the processor configured to determine a quantitative measure of a fluid within a local detection volume from the detected signal in accordance with a predetermined capacitive relationship between the first electrode, the detection volume, and the fluid.

13. The system of claim 12, wherein the field sensor further comprises an analog signal generator, an analog signal detector, and a digital converter receiving input from the detector, the converter supplying digital output as input to the processor.

14. The system of claim 13, wherein the processor comprises a dedicated input port for digitally converted signals from each of the respective electrodes.

15. The system of claim 14, further comprising means for generating an alert.

16. The system of claim 12, further comprising a series of discrete second electrodes opposite the series of discrete first electrodes.

17. A sensor system comprising:

a first electrode and a second electrode adapted to create an electric field within a detection volume;

an electrical field sensor communicatively coupled to the first and second electrodes, the electrical field sensor configured to generate a detected signal responsive to a change in the electric field; and

a processor coupled to the electrical field sensor, the processor configured to determine a quantitative measure of a fluid within the detection volume from the detected signal in accordance with a predetermined relationship between the fluid quantitative measure and a ratio of an area A₁ of the first electrode to an area A₂ of the second electrode.

18. The system of claim 17, wherein the electrodes are rectangular strips.

19. The system of claim 17, further comprising a reference electrode located to sense fluid continuously while the system is in use.

20. The system of claim 19, wherein the processor is further configured to determine a quantitative measure of fluid by including a dimensional and capacitive relationship between the first electrode and the reference electrode.

21. The system of claim 17, wherein in the first electrode comprises a triangular strip and the second electrode comprises a complementary triangular strip, such that summing equal length complementary segments provides a constant area.

22. (canceled)

23. An electric field sensor system for detecting proximity of an object, the system comprising:

an array of electrodes adapted to create an electric field within a detection volume, the electrodes aligned spatially from a characteristic surface of an object in the electric field;

an electrical field sensor communicatively coupled to the electrodes, the electrical field sensor configured to generate a signal responsive to a change in the electric field; and

a processor coupled to the electrical field sensor, the processor configured to determine a displacement measure of a body within the detection volume from the signal in accordance with a predetermined capacitive relationship between the electrodes, the detection volume, and the body.

24. The system of claim 23, wherein the capacitive relationship comprises:

25. The system of claim 24, wherein the characteristic surface comprises a portion of an outer surface of an object.

26. The system of claim 25, wherein the object is a vertical drum of a laundry washing machine.

27. The system of claim 25, wherein the object is a horizontal drum of a front loading washing machine.

28. The system of claim 26, wherein the array comprises a grid of electrodes in a plane parallel to a base of the drum.

29. The system of claim 27, wherein the array is aligned in a plane parallel to an axis of rotation of the drum.