Capacitive sensor with orthogonal fields

• US 9,395,171 B2
• Filed: 11/05/2012
• Issued: 07/19/2016
• Est. Priority Date: 11/05/2012
• Status: Active Grant

• Current Assignee: Siemens Energy Incorporated (Siemens AG)
• Original Assignee: Siemens Energy Incorporated (Siemens AG)
• Inventors: Tevs, Nikolai R.
• Primary Examiner(s): Phan, Huy Q
• Assistant Examiner(s): RHODES-VIVOUR, TEMILADE S
• Application Number:
  US13/668,345
• Publication Number:
  US 20140125361A1
• Time in Patent Office: 1,352 Days
• Field of Search: 324/458, 324/679, 324/609, 324/658, 324/661, 324/663, 324/665, 324/672, 324/686, 324/693, 324/695, 324/705, 324/162, 324/161, 324/163, 324/165, 324/176, 324/76.74, 324/76.78
• US Class Current: 1/1
• CPC Class Codes: C12Q 2326/00 Chromogens for determinations of oxidoreductase enzymes
• CPC Class Codes: G01B 7/023 for measuring distance between sensor and object G01B7/082 and G01B7/102 take precedence
• CPC Class Codes: G01D 5/2405 by varying dielectric
• CPC Class Codes: H01L 21/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
• CPC Class Codes: H01L 2221/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00

Abstract

A method and system for determining a distance from a probe to an object includes generating a first electric field by applying a first signal across a first pair of electrodes aligned along a first axis and generating a second electric field by applying a second signal across a second pair of electrodes aligned along a second axis substantially perpendicular to the first axis. After generating the signals, a first change in the first signal due to the object interacting with the first electric field and a second change in the second signal due to the object interacting with the second electric field is concurrently detected. A distance of the object from the first and second pair of electrodes can be calculated based on a ratio of the first and second changes.

Claims

1. A proximity sensor comprising:

a first pair of electrodes aligned along a first axis;

a second pair of electrodes aligned along a second axis substantially perpendicular to the first axis;

a signal generator configured to apply a first signal across the first pair of electrodes to produce a first electric field and to apply a second signal across the second pair of electrodes to produce a second electric field that is substantially perpendicular to the first electric field, wherein the first and second electric fields are produced concurrently;

a detector configured to concurrently detect a first change in the first signal due to an object interacting with the first electric field and a second change in the second signal due to the object interacting with the second electric field; and

a comparator configured to determine a distance of the object from the first and second pair of electrodes based on a ratio of the first and second changes.

2. The proximity sensor of claim 1, wherein:

the first pair of electrodes are separated along the first axis by a first distance; and

the second pair of electrodes are separated along the second axis by a second distance different than the first distance.

3. The proximity sensor of claim 2, wherein the first distance is about twice as much as the second distance.

4. The proximity sensor of claim 1, wherein the first signal is a radio frequency signal having a first frequency and the second signal is a radio frequency signal having a second frequency different than the first frequency.

5. The proximity sensor of claim 4, wherein each of the first and second frequencies are between about 1 MHz and 100 MHz.

6. The proximity sensor of claim 1, wherein the first change relates to a change in amplitude of the first signal and the second change relates to a change in amplitude of the second signal.

7. The proximity sensor of claim 1, wherein the first change relates to a change in phase of the first signal and the second change relates to a change in phase of the second signal.

8. The proximity sensor of claim 1, wherein the first change relates to a change in frequency of the first signal and the second change relates to a change in frequency of the second signal.

9. The proximity sensor of claim 1, wherein the first and second pairs of electrodes are attached to a probe configured to be located within a high temperature region of a gas turbine engine.

10. A method for determining a distance from a probe to an object, comprising:

generating a first electric field by applying a first signal across a first pair of electrodes aligned along a first axis;

generating, concurrently with the first electric field, a second electric field by applying a second signal across a second pair of electrodes aligned along a second axis substantially perpendicular to the first axis, wherein the first electric field is substantially perpendicular to the second electric field;

concurrently detecting a first change in the first signal due to the object interacting with the first electric field and a second change in the second signal due to the object interacting with the second electric field; and

calculating a distance of the object from the first and second pair of electrodes based on a ratio of the first and second changes.

11. The method of claim 10, wherein:

the first pair of electrodes are separated along the first axis by a first distance; and

the second pair of electrodes are separated along the second axis by a second distance different than the first distance.

12. The method of claim 11, wherein the first distance is about twice as much as the second distance.

13. The method of claim 10, wherein the first signal is a radio frequency signal having a first frequency and the second signal is a radio frequency signal having a second frequency different than the first frequency.

14. The method of claim 13, wherein each of the first and second frequencies are between about 1 MHz and 100 MHz.

15. The method of claim 10, wherein the first change relates to a change in amplitude of the first signal and the second change relates to a change in amplitude of the second signal.

16. The method of claim 10, wherein the first change relates to a change in phase of the first signal and the second change relates to a change in phase of the second signal.

17. The method of claim 10, wherein the first change relates to a change in frequency of the first signal and the second change relates to a change in frequency of the second signal.

18. The method of claim 10, comprising:

positioning the probe within a high temperature region of a gas turbine engine, and wherein the object is a rotating blade of the gas turbine engine.

19. A capacitive probe comprising:

a sensor body upper surface;

a first electrode located on the sensor body upper surface, the first electrode having a first top portion extending above the sensor body upper surface and a first bottom portion, opposite the first top portion, configured for electrical communication with a first electromagnetic signal;

a second electrode located on the sensor body upper surface, the second electrode having a second top portion extending above the sensor body upper surface and a second bottom portion, opposite the second top portion, configured for electrical communication with the first electromagnetic signal, wherein the first and second electrodes are aligned along a first axis;

a third electrode located on the sensor body upper surface, the third electrode having a third top portion extending above the sensor body upper surface and a third bottom portion, opposite the third top portion, configured for electrical communication with a second electromagnetic signal; and

a fourth electrode located on the sensor body upper surface, the fourth electrode having a fourth top portion extending above the sensor body upper surface and a fourth bottom portion, opposite the fourth top portion, configured for electrical communication with the second electromagnetic signal, wherein the third and fourth electrodes are aligned along a second axis substantially perpendicular to the first axis.

20. The capacitive probe of claim 19, wherein:

the first and second electrodes are separated by a first distance along the first axis; and

the third and fourth electrodes are separated by a second distance along the second axis, wherein the second distance is substantially twice the first distance.