SYSTEMS AND METHODS FOR DETECTING LOW GROUND MASS CONDITIONS IN SENSOR DEVICES

• US 20130173211A1
• Filed: 12/28/2011
• Published: 07/04/2013
• Est. Priority Date: 12/28/2011
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Hoch, David, Bulea, Mihai
• Granted Patent: US 9,965,105 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A processing system for an input device includes a sensor module and a determination module. The sensor module includes sensor circuitry and is configured to acquire a first plurality of measurements of change in capacitive coupling between each sensor electrode of a first set of sensor electrodes and a second set of sensor electrodes. The sensor module is further configured to acquire a second plurality of measurements of change in capacitive coupling between each sensor electrode of the second set of sensor electrodes and an input object. The determination module is configured to determine a first combined measurement based on the first plurality of measurements, determine a second combined measurement based on the second plurality of measurements, and determine positional information for the input object based on a low ground mass parameter. The low ground mass parameter is based on the first combined measurement and the second combined measurement.

Claims

1. A processing system for an input device, the processing system comprising:

a sensor module comprising sensor circuitry, the sensor module configured to;

acquire a first plurality of measurements of change in capacitive coupling between sensor electrodes of a first set of sensor electrodes and sensor electrodes of a second set of sensor electrodes; and

acquire a second plurality of measurements of change in capacitive coupling between each sensor electrode of the second set of sensor electrodes and an input object; and

a determination module configured to;

determine a first combined measurement based on the first plurality of measurements;

determine a second combined measurement based on the second plurality of measurements; and

determine positional information for the input object based on a low ground mass parameter, wherein the low ground mass parameter is based on the first combined measurement and the second combined measurement.

2. The processing system of claim 1, wherein the determination module is further configured to determine the positional information for the input object based on the first plurality of measurements and wherein the determination module is configured to determine the positional information for the input object selectably based on at least one of the low ground mass parameter and the first plurality of measurements.

3. The processing system of claim 2, wherein the determination module is configured to base the position information on the low ground mass parameter when the low ground mass parameter meets a criterion.

4. The processing system of claim 1, wherein the low ground mass parameter is based on at least one of:

a low ground mass coefficient;

a free-space coupling coefficient;

a first sensor electrode coupling coefficient corresponding to capacitive coupling of the input object to the first set of sensor electrodes; and

a second sensor electrode coupling coefficient corresponding to capacitive coupling of the input object to the second set of sensor electrodes.

5. The processing system of claim 4, wherein the low ground mass parameter is based on a combination of the first sensor coupling coefficient, the second sensor coupling coefficient, and the free space coupling coefficient.

6. The processing system of claim 1, wherein:

the sensor module is further configured to acquire a third plurality of measurements of change in capacitive coupling between each sensor electrode of the first set of sensor electrodes and the input object; and

the determination module is further configured to determine a third combined measurement based on the third plurality of measurements, and wherein the low ground mass parameter is further based on the third combined measurement.

7. The processing system of claim 1, wherein the first combined measurement comprises a first projection corresponding to a projection of the first plurality of measurements, and the second combined measurement comprises a second projection corresponding to a projection of the second plurality of measurements.

8. The processing system of claim 7, wherein the low ground mass parameter is based on at least one of a difference in shape and a difference in amplitude between the first projection and the second projection.

9. The processing system of claim 7, wherein determining the positional information for the input object based on a low ground mass parameter comprising determining the positional information for the input object based on a model applied to the low ground mass parameter and at least one of the first projection and the second projection.

10. The processing system of claim 1, wherein the first plurality of measurements and the second plurality of measurements are acquired substantially simultaneously.

11. The processing system of claim 1, wherein the first set of sensor electrodes is substantially parallel to the second set of sensor electrodes or substantially perpendicular to the second set of sensor electrodes.

12. The processing system of claim 1, wherein the processing system is configured to determine an operational state of the input device based on the low ground mass parameter.

13. A capacitive sensor device comprising:

a first set of electrodes;

a second set of electrodes; and

a processing system communicatively coupled to the first set of electrodes and the second set of electrodes, the processing system configured to;

acquire a first plurality of measurements of change in capacitive coupling between sensor electrodes of a first set of sensor electrodes and sensor electrodes of a second set of sensor electrodes; and

acquire a second plurality of measurements of change in capacitive coupling between each sensor electrode of the second set of sensor electrodes and an input object;

determine a first combined measurement based on the first plurality of measurements;

determine a second combined measurement based on the second plurality of measurements; and

determine positional information for the input object based on a low ground mass parameter, wherein the low ground mass parameter is based on the first combined measurement and the second combined measurement.

14. The capacitive sensor device of claim 13, wherein the processing system is further configured to determine the positional information for the input object based on the first plurality of measurements and wherein the processing system is configured to determine the positional information for the input object selectably based on at least one of the low ground mass parameter and the first plurality of measurements.

15. The capacitive sensor device of claim 13, wherein the low ground mass parameter is based on at least one of:

a low ground mass coefficient;

a free-space coupling coefficient;

a first sensor coupling coefficient corresponding to capacitive coupling of the input object to the first set of sensor electrode; and

a second sensor coupling coefficient corresponding to capacitive coupling of the input object to the second set of sensor electrodes.

16. The processing system of claim 13, wherein determining the positional information for the input object based on a low ground mass parameter comprising determining the positional information for the input object based on a model applied to the low ground mass parameter and at least one of the first projection and the second projection.

17. A method of capacitive sensing, the method comprising:

acquiring a first plurality of measurements of change in capacitive coupling between sensor electrodes of a first set of sensor electrodes and sensor electrodes of a second set of sensor electrodes;

acquiring a second plurality of measurements of change in capacitive coupling between each sensor electrode of the second set of sensor electrodes and an input object;

determining a first combined measurement based on the first plurality of measurements;

determining a second combined measurement based on the second plurality of measurements;

determining positional information for the input object based on a low ground mass parameter, wherein the low ground mass parameter is based on the first combined measurement and the second combined measurement.

18. The method of claim 17, wherein:

determining the first combined measurement comprises determining a first projection corresponding to a projection of the first plurality of measurements;

determining the second combined measurement comprises determining a second projection corresponding to a projection of the second plurality of measurements; and

determining the positional information for the input object comprises applying a model to the low ground mass parameter and at least one of the first projection and the second projection.

19. The method of claim 17, wherein the low ground mass parameter is based on at least one of:

a low ground mass coefficient;

a free-space coupling coefficient;

a first sensor coupling coefficient corresponding to capacitive coupling of the input object to the first set of sensor electrode; and

a second sensor coupling coefficient corresponding to capacitive coupling of the input object to the second set of sensor electrodes.

20. The method of claim 17, wherein the low ground mass parameter is based on at least one of a difference in shape and a difference in amplitude between the first projection and the second projection.