Classifying input objects interacting with a capacitive button

• US 9,304,643 B2
• Filed: 06/24/2014
• Issued: 04/05/2016
• Est. Priority Date: 06/24/2014
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Synaptics Incorporated
• Inventors: Jordan, Joel C., Schwartz, Adam
• Primary Examiner(s): Cheng, Joe H
• Application Number:
  US14/313,711
• Publication Number:
  US 20150370364A1
• Time in Patent Office: 651 Days
• US Class Current: 1/1
• CPC Class Codes: G01B 2210/58 Wireless transmission of information between a sensor or probe and a control or evaluation unit
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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

Abstract

Embodiments of the invention generally provide an input device that includes a zero-dimensional button that detects whether an input object is proximate to a sensing region. However, different input objects may provide similar responses which may prevent the input device from accurately determining whether the user actually intended to activate the button. In one embodiment, the input device drives a capacitive sensing signal onto a sensor electrode in the capacitive button and measures at least two resulting signals. The input device then derives capacitance values based on the two resulting signals and uses a ratio between the capacitance values to classifying the interaction with the input object. This ratio enables the input device to distinguish between events that have similar capacitive responses and would otherwise be indistinguishable if only one resulting signal were measured.

Claims

1. An input device, comprising:

a first plurality of sensor electrodes;

a second plurality of sensor electrodes;

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

operate the first plurality of sensor electrodes to detect positional information for an input object in a first sensing region;

operate the second plurality of sensor electrodes to detect a presence of the input object in a second sensing region by;

driving a capacitive sensing signal to detect the input object onto at least one of the second plurality of sensor electrodes,

receiving a first resulting signal and a second resulting signal on one or more sensor electrodes of the second plurality of sensor electrodes based on driving the capacitive sensing signal, and

determining whether the input object is contacting the second sensing region based on a ratio between the first and second resulting signals.

2. The input device of claim 1, wherein one of:

(i) the first resulting signal is received on a first sensor electrode of the second plurality of sensor electrodes, the second resulting signal is received on a second, different sensor electrode of the second plurality of sensor electrodes, and the capacitive sensing signal is driven onto a third sensor electrode of the second plurality of sensor electrodes different from the first and second sensor electrodes and (ii) the capacitive sensing signal is driven on multiple sensor electrodes of the second plurality of sensor electrodes at different time intervals and the first and second resulting signals are received using only one of the second plurality of sensor electrodes.

3. The input device of claim 1, wherein the processing system is configured to:

determine that the input object is contacting the second sensing region if (i) the ratio satisfies a first predetermined threshold and (ii) a value of the first resulting signal satisfies a second predetermined threshold; and

classifying the input object as a contacting finger, a hovering finger, or a contacting stylus based on the first and second resulting signals.

4. The input device of claim 1, wherein the processing system is configured to:

determine that the input object is a stylus contacting the second sensing region when (i) the ratio satisfies a first predetermined threshold and (ii) a value of the first resulting signal satisfies a second predetermined threshold; and

determine that the input object is a finger contacting the second sensing region when (i) the value of the first resulting signal satisfies a third predetermined threshold greater than the second predetermined threshold.

5. The input device of claim 1, wherein the first sensing region detects the positional information of the input object in at least two dimensions and the second sensing region is a zero-dimensional sensing region.

6. The input device of claim 1, wherein a first sensor electrode of the second plurality of sensor electrodes in the second sensing region is ohmically coupled to a first sensor electrode of the first plurality of sensor electrodes in the first sensing region, and wherein the processing system is configured to simultaneously drive the capacitive sensing signal on both the first sensor electrode of the second plurality of sensor electrodes and the first sensor electrode of the first plurality of sensor electrodes.

7. The input device of claim 1, wherein a first sensor electrode of the second plurality of sensor electrodes in the second sensing region is ohmically coupled to a first sensor electrode of the first plurality of sensor electrodes in the first sensing region, and wherein the processing system is configured to receive the first or second resulting signal from the first sensor electrode of the second plurality of sensor electrodes via the first sensor electrode of the first plurality of sensor electrodes.

8. The input device of claim 1, further comprising:

an electrically floating conductor that overlaps at least a portion of one of the second plurality of sensor electrodes.

9. The input device of claim 1, wherein the processing system is configured to perform transcapacitive sensing in the second sensing region by driving the capacitive sensing signal onto a first sensor electrode of the second plurality of sensor electrodes and receiving the first and second resulting signal on respective sensor electrodes of the second plurality of sensor electrodes different from the first sensor electrode.

10. The input device of claim 1, wherein the processing system is configured to perform absolute capacitive sensing in the second sensing region by (i) driving the capacitive sensing signal onto a first sensor electrode of the second plurality of sensor electrodes and receiving the first resulting signal on the first sensor electrode and (ii) driving the capacitive sensing signal onto a second sensor electrode of the second plurality of sensor electrodes and receiving the second resulting signal on the second sensor electrode.

11. A processing system, comprising:

a sensor module configured to couple to a first plurality of sensor electrodes to detect a presence of an input object in a zero-dimensional sensing region, the sensor module configured to;

drive a capacitive sensing signal to detect the input object onto at least one of the first plurality of sensor electrodes, and

receive a first resulting signal and a second resulting signal on one or more sensor electrodes of the first plurality of sensor electrodes based on driving the capacitive sensing signal; and

a determination module configured to determine whether the input object is contacting the zero-dimensional sensing region based on a ratio between the first and second resulting signals.

12. The processing system of claim 11, wherein the determination module is configured to determine that the input object is contacting the sensing region if (i) the ratio satisfies a first predetermined threshold and (ii) a value of the first resulting signal satisfies a second predetermined threshold.

13. The processing system of claim 11, wherein the sensor module is configured to couple to a second plurality of sensor electrodes, the sensor module configured to drive the capacitive signal onto the second plurality of sensor electrodes to determine a position of the input object in a different sensing region in at least two dimensions.

14. The processing system of claim 13, wherein the sensor module is configured to simultaneously drive the capacitive sensing signal on both a first sensor electrode of the first plurality of sensor electrodes and a first sensor electrode of the second plurality of sensor electrodes.

15. The processing system of claim 11, wherein the sensor module is configured to perform transcapacitive sensing in the zero-dimensional sensing region by driving the capacitive sensing signal onto a first sensor electrode of the first plurality of sensor electrodes and receiving the first and second resulting signal on respective sensor electrodes of the first plurality of sensor electrodes different from the first sensor electrode.

16. The processing system of claim 11, wherein the sensor module is configured to perform absolute capacitive sensing in the zero-dimensional sensing region by (i) driving the capacitive sensing signal onto a first sensor electrode of the first plurality of sensor electrodes and receiving the first resulting signal on the first sensor electrode and (ii) driving the capacitive sensing signal onto a second sensor electrode of the first plurality of sensor electrodes and receiving the second resulting signal on the second sensor electrode.

17. A method, comprising:

driving a capacitive sensing signal onto at least one of a first plurality of sensor electrodes to detect a presence of an input object in a zero-dimensional sensing region;

receiving a first resulting signal and a second resulting signal on one or more sensor electrodes of the first plurality of sensor electrodes based on driving the capacitive sensing signal; and

determining whether the input object is contacting the zero-dimensional sensing region based on a ratio between the first and second resulting signals.

18. The method of claim 17, wherein determining that the input object is contacting zero-dimensional sensing region further comprises determining that (i) the ratio satisfies a first predetermined threshold and (ii) a value of the first resulting signal satisfies a second predetermined threshold.

19. The method of claim 17, further comprising:

performing capacitive sensing in a different sensing region in at least two dimensions, the different sensing region comprising a second plurality of sensor electrodes,

wherein at least one of the sensor electrodes of the second plurality of sensor electrodes is ohmically coupled to at least one of the sensor electrodes in the first plurality of sensor electrodes.

20. The method of claim 17, further comprising:

performing absolute capacitive sensing in the zero-dimensional sensing region by (i) driving the capacitive sensing signal onto a first sensor electrode of the first plurality of sensor electrodes and receiving the first resulting signal on the first sensor electrode and (ii) driving the capacitive sensing signal onto a second sensor electrode of the first plurality of sensor electrodes and receiving the second resulting signal on the second sensor electrode.

21. The method of claim 17, further comprising:

performing transcapacitive sensing in the zero-dimensional sensing region by driving the capacitive sensing signal onto a first sensor electrode of the first plurality of sensor electrodes and receiving the first and second resulting signal on respective sensor electrodes of the first plurality of sensor electrodes different from the first sensor electrode.

22. The method of claim 17, wherein the zero-dimensional sensing region is a capacitive button and the first plurality of sensor electrodes comprises a first sensor electrode that receives the first resulting signal and a second sensor electrode that receives the second resulting signal, wherein at least a portion of the first sensor electrode is at a center of the capacitive button and no portion of the second sensor electrode is at the center of the capacitive button.