Capacitive coupling for connection of remotely placed capacitive sensing electrodes

Patent metadata

Field	Value
Publication number	US-11863173-B2
Application number	US-201916543874-A
Country	US
Kind code	B2
Filing date	Aug 19, 2019
Priority date	Aug 20, 2018
Publication date	Jan 2, 2024
Grant date	Jan 2, 2024

Abstract

A system includes a housing, a sensing electrode disposed within the housing, and a connecting electrode. The system also includes a capacitive sensing circuit galvanically connected to the connecting electrode at a first port, but not to the sensing electrode. The capacitive sensing circuit is configured to determine a first capacitance between the first port and a ground. The first capacitance includes a variable capacitance between the connecting electrode and a person when the person is touching the housing.

First claim

What is claimed is:

1. A system, comprising:
a housing having an outer surface and an inner surface, the inner surface defining an internal volume;
a sensing electrode disposed within the housing;
a connecting electrode disposed on the inner surface within the internal volume; and
a capacitive sensing circuit galvanically connected to the connecting electrode at a first port, but not to the sensing electrode, the capacitive sensing circuit configured to:
determine a first capacitance between the first port and a ground, the first capacitance including a variable capacitance between the connecting electrode and a person when the person is touching the housing;
determine a second capacitance between the first port and the ground associated with a time when the person is not touching the housing; and
determine a difference between the second capacitance and the first capacitance.

2. The system of claim 1 , wherein:
the sensing electrode is disposed within the housing between the inner and outer surfaces.

3. The system of claim 2 , wherein the capacitive sensing circuit is disposed within the internal volume.

4. The system of claim 2 , wherein the sensing electrode is a first sensing electrode and the connecting electrode is a first connecting electrode, and the system further includes:
a second sensing electrode disposed within the housing between the inner and outer surfaces; and
a second connecting electrode disposed on the inner surface within the internal volume;

wherein the capacitive sensing circuit is galvanically connected to the first and second connecting electrodes, but not to the first and second sensing electrodes.

5. The system of claim 1 , wherein the capacitive sensing circuit includes a charge transfer capacitor, and the capacitive sensing circuit is configured to determine the first capacitance through transfer of charge from the first capacitance to the charge transfer capacitor.

6. The system of claim 1 , wherein the capacitive sensing circuit includes a control circuit and a capacitor, and the capacitive sensing circuit is configured to:
in a first state, couple the first port to a fixed voltage reference; and
in a second state, couple the first port to the control circuit to transfer charge from the first port to the capacitor.

7. The system of claim 1 , wherein the system comprises a tool.

8. The system of claim 1 , wherein the system comprises a drill.

9. A device comprising:
a capacitive sensing circuit having a port coupled to a first switch and a second switch, the capacitive sensing circuit further comprising a control circuit coupled to the first switch and the second switch, and to a transfer capacitor;
a conductor coupled to the port of the capacitive sensing circuit;
a first electrode coupled to the conductor;
a housing having a first surface and a second surface, the second surface disposed inside a first volume defined by the first surface, the second surface defining a second volume, wherein the first electrode is coupled to the housing; and
a second electrode disposed on the second surface and within the second volume of the housing, wherein the second electrode is capacitively coupled to the first electrode.

10. The device of claim 9 , wherein the housing includes a first region of non-conductive material disposed between the first electrode and the second electrode.

11. The device of claim 10 , wherein the first surface is an outer surface and a second region of non-conductive material disposed between the second electrode and the outer surface.

12. The device of claim 11 , wherein the first and second regions of non-conductive material are deformable.

13. The device of claim 9 , wherein the control circuit of the capacitive sensing circuit is configured to calculate an amount of charge transferred between a capacitance at the port to the transfer capacitor.

14. The device of claim 9 , wherein the control circuit of the capacitive sensing circuit is configured to control the first switch and the second switch to charge a capacitance at the port.

15. The device of claim 14 , wherein the first switch comprises a state opposite of a state of the second switch.

16. An apparatus, comprising:
a sensing electrode;
a housing with an outer surface and an inner surface, the inner surface enclosing an internal volume, wherein the sensing electrode is disposed between the outer surface and the inner surface;
a connecting electrode aligned with the sensing electrode and disposed within the internal volume of the housing;
a non-conductive region between the connecting electrode and the sensing electrode, the non-conductive region capacitively coupling the connecting electrode and the sensing electrode; and
a capacitive sensing circuit coupled to the connecting electrode.

17. The apparatus of claim 16 , wherein the connecting electrode is attached to the inner surface of the housing.

18. The apparatus of claim 16 , wherein the connecting electrode is radially and longitudinally aligned with the sensing electrode.

19. The apparatus of claim 16 , wherein a capacitance between the sensing electrode and the connecting electrode depends on at least one of the non-conductive region, a distance between the sensing electrode and the connective electrode, and an overlapping area of the sensing electrode and the connective electrode.

20. The apparatus of claim 16 , wherein the capacitive sensing circuit is configured to detect a user's hand on the housing by measuring a total capacitance at a port of the capacitive sensing circuit, the total capacitance including a variable capacitance and a capacitance between the sensing electrode and the connecting electrode.

Assignees

• Texas Instruments Inc

Inventors

• Spevak Peter

Classifications

• H10D1/692 Primary

  Electrodes · CPC title

• H03K17/962 Primary

  Capacitive touch switches · CPC title

• G01R27/2605

  Measuring capacitance (capacitive sensors G01D5/24) · CPC title

• G06F3/044

  by capacitive means · CPC title

• H01L28/60

  Electricity · mapped topic