Cancelling induced currents in a touch sensing device having an embedded near field communication antenna

• US 8,933,901 B2
• Filed: 07/09/2012
• Issued: 01/13/2015
• Est. Priority Date: 07/07/2011
• Status: Active Grant

• Current Assignee: Cirque Corporation (Alps Alpine Co., Ltd.)
• Original Assignee: Cirque Corporation (Alps Alpine Co., Ltd.)
• Inventors: Paulsen, Keith L.
• Primary Examiner(s): ABDIN, SHAHEDA A
• Application Number:
  US13/544,456
• Publication Number:
  US 20130009895A1
• Time in Patent Office: 918 Days
• Field of Search: 345173-175, 178 1801- 1805, 349/158, 349/96, 349/122, 349/137, 349/138
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/046 by electromagnetic means
• CPC Class Codes: G09G 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T
• CPC Class Codes: H01Q 1/22 by structural association with other equipment or articles

Abstract

A method and system for enabling a near field communication antenna to be disposed adjacent to electrodes of a touch sensing device, the near field communication antenna being operated, and the magnetic field inductance and electric field coupling between the electrodes and the near field communication antenna being minimized in order to substantially reduce or eliminate induced currents on the electrodes.

Claims

1. A method for reducing induced current in electrodes of a touch sensing device that is operating adjacent to a near field communication antenna, said method comprising:

1) providing a plurality of electrodes that form a sensing area used in a touch sensing device;

2) providing a near field communication antenna disposed adjacent to the plurality of electrodes; and

3) reducing induced current in the plurality of electrodes caused by operation of the near field communication antenna by configuring the electrodes to reduce the effect of electromagnetic fields generated by the near field communication antenna by arranging the plurality of electrodes to form a sensing area having a plurality of concentrically aligned electrode loops, the loops all being electrically open at a first location, and having a connection to touch sensing circuitry at an opposite second location, each of the electrode loops thereby having two arms of substantially equal length, the induced current in a first arm of each of the plurality of concentrically aligned electrode loops being equal and opposite to the induced current in a second arm of each of the plurality of concentrically aligned electrode loops to thereby result in a reduced induced current in each of the plurality of concentrically aligned electrode loops.

2. The method as defined in claim 1 wherein the method further comprises aligning the plurality of concentrically aligned electrode loops such that the electrically open first locations are aligned, and the opposite second locations are aligned.

3. The method as defined in claim 1 wherein the method further comprises providing a first signal source that is coupled to a first end of the near field communication antenna and a second signal source that is coupled to a second end of the near field communication antenna, the first signal source being approximately 180 degrees out of phase with the second signal source, wherein an electrostatic field coupled to the plurality of electrodes thereby produces a net change of substantially no voltage in the plurality of electrodes.

4. The method as defined in claim 1, the method further comprising:

1) providing the plurality of electrodes in a first plane and the near field communication antenna in a second plane; and

2) providing four triangular loops to form a near field communication antenna, the loops being non-overlapping and in a second plane that is parallel to the first plane.

5. A system for reducing induced current in electrodes of a touch sensing device that is operating adjacent to a near field communication antenna, said system comprised of:

a plurality of electrodes that form a sensing area used in a touch sensing device;

a near field communication antenna disposed adjacent to the plurality of electrodes, the plurality of electrodes being configured so as to reduce the effect of electromagnetic fields generated by the near field communication antenna and thereby reducing induced current in the plurality of electrodes caused by operation of the near field communication antenna, wherein the system further comprises a plurality of concentrically aligned electrode loops forming a sensing area, the loops all being electrically open at a first location, and having a connection to touch sensing circuitry at an opposite second location, each of the plurality of concentrically aligned electrode loops thereby having two arms of substantially equal length, the induced current in a first arm of each of the plurality of concentrically aligned electrode loops being equal and opposite to the induced current in a second arm of each of the plurality of concentrically aligned electrode loops to thereby result in a reduced induced current in each of the plurality of concentrically aligned electrode loops.

6. The system as defined in claim 5 wherein the system is further comprised of aligning the plurality of concentrically aligned electrode loops such that the electrically open first locations are all aligned, and the opposite second locations are all aligned.

7. The system as defined in claim 6 wherein the system is further comprised of:

a first signal source that is coupled to a first end of the near field communication antenna; and

a second signal source that is coupled to a second end of the near field communication antenna, the first signal source being approximately 180 degrees out of phase with the second signal source such that an electrostatic field coupled from the near field communication antenna to the plurality of electrodes thereby produces a net change of substantially no voltage in the plurality of electrodes.

8. A method for reducing induced current in electrodes of a touch sensing device that is operating adjacent to a near field communication antenna, said method comprising:

1) providing a plurality of electrodes that form a sensing area used in a touch sensing device, the plurality of electrodes forming a plurality of concentrically aligned partial electrode loops, the loops all being electrically open at a first location, and having a connection to touch sensing circuitry at an opposite second location, each of the electrode loops thereby having two arms of substantially equal length, the induced current in a first arm of each of the plurality of concentrically aligned electrode loops being equal and opposite to the induced current in a second arm of each of the plurality of concentrically aligned electrode loops;

2) providing a near field communication antenna disposed adjacent to the plurality of electrodes; and

3) providing a first signal source that is coupled to a first end of the near field communication antenna and a second signal source that is coupled to a second end of the near field communication antenna, the first signal source being approximately 180 degrees out of phase with the second signal source, wherein an electrostatic field coupled to the plurality of electrodes thereby produces a net change of substantially no voltage in the plurality of electrodes.

9. A system for reducing induced current in electrodes of a touch sensing device that is operating adjacent to a near field communication antenna, said system comprised of:

an electrode grid forming a rectangular sensing area in a first plane of a touch sensing device;

four triangular loops forming a near field communication antenna, the loops being non-overlapping and in a third plane that is parallel to the first plane, open ends of the loops meeting near a center of the electrode grid, an outer edge of the four triangular loops forming a rectangular outline sharing a common center with the rectangular sensing area; and

a differential signal source coupled to the open ends of the four triangular loops, adjacent ends of the four triangular loops always being coupled to opposite ends of the differential signal source.

10. The system as defined in claim 9 wherein the electrode grid is further comprised of:

a plurality of parallel electrodes in a first orientation or axis in the first plane; and

a plurality of parallel electrodes in a second orientation or axis that is in a second plane that is parallel to the first plane, the plurality of electrodes oriented so as to be orthogonal to the first orientation.

11. The system as defined in claim 9 wherein the differential signal source is further comprised of:

a first signal source; and

a second signal source that is 180 degrees out of phase with the first signal source.

12. A method for reducing induced current in electrodes of a touch sensing device that is operating adjacent to a near field communication antenna, said method comprising:

1) providing an electrode grid forming a rectangular sensing area in a first plane of a touch sensing device;

2) providing four triangular loops to form a near field communication antenna, the loops being non-overlapping and in a second plane that is parallel to the first plane; and

3) coupling a differential signal source to the four triangular loops; and

4) reducing induced current in the electrode grid caused by operation of the near field communication antenna by configuring the electrode grid and the near field communication antenna to reduce the effect of electromagnetic fields generated by the near field communication antenna.

13. The method as defined in claim 12 wherein the method further comprises reducing induced current in the electrode grid caused by a magnetic field generated by the near field communication antenna.

14. The method as defined in claim 12 wherein the method further comprises reducing induced current in the electrode grid caused by coupling of an electric field generated by the near field communication antenna.