SENSOR MATRIX PAD FOR PERFORMING MULTIPLE CAPACITIVE SENSING TECHNIQUES

• US 20150227229A1
• Filed: 02/11/2014
• Published: 08/13/2015
• Est. Priority Date: 10/18/2013
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: SCHWARTZ, Adam, SHEPELEV, Petr
• Granted Patent: US 9,274,662 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• 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
• CPC Class Codes: G06F 3/0448 Details of the electrode shape, e.g. for enhancing the detection of touches, for generating specific electric field shapes, for enhancing display quality

Abstract

Embodiments in the present disclosure use various individual electrodes in a capacitive sensing pixel of an electrode matrix to perform two different techniques of capacitive sensing. For example, a capacitive sensing pixel may include at least two sensor electrodes that may be driven different by a processing system depending on the current capacitive technique being used to user interaction. When performing absolute capacitive sensing, a first one of the sensor electrodes may be driven with a modulated signal in order to measure a change in absolute capacitance between the driven sensor electrode and an input object. Alternatively, when performing transcapacitance sensing, the first sensor electrode is driven with a transmitter signal while a resulting signal is measured on a second sensor electrode in the capacitive pixel. In this manner, the individual electrodes in a capacitive sensing pixel may be driven differently depending on the current capacitive sensing technique.

Claims

1. An input device comprising:

a display device;

a plurality of sensor electrodes that establish a sensing region of the input device; and

a processing system coupled to the plurality of sensor electrodes, the processing system is configured to;

perform absolute capacitive sensing during a first time period by driving a modulated signal on at least one of a first sensor electrode of the plurality of sensor electrodes and a second sensor electrode of the plurality of sensor electrodes to determine a change in capacitive coupling between the driven sensor electrode and an input object, wherein the first and second sensor electrodes are disposed on a same plane in the input device, and

perform transcapacitance sensing during a second time period by driving a transmitter signal onto the first sensor electrode and measuring a resulting signal on the second sensor electrode.

2. The input device of claim 1, wherein the second sensor electrode at least partially encircles the first sensor electrode within the same plane.

3. The input device of claim 1, wherein a plan area of the first sensor electrode is larger than a plan area of the second sensor electrode.

4. The input device of claim 1, wherein a third sensor electrode of the plurality of sensor electrodes is disposed on the same plane and at least partially encircles both the first and second sensors.

5. The input device of claim 4, wherein, when determining a change in capacitive coupling between the driven sensor electrode and the input object, at least one of the first, second, and third sensor electrodes is driven with a guarding signal and at least one of the first, second and third sensor electrodes is driven with a substantially constant voltage.

6. The input device of claim 4, wherein, when performing transcapacitance sensing, the third sensor electrode is driven with one of a guarding signal and a substantially constant voltage.

7. The input device of claim 1, further comprising a display driver module configured to drive a plurality of common electrodes to update a display, wherein each of the plurality of sensor electrodes comprises at least one common electrode.

8. The input device of claim 1, wherein the plurality of sensor electrodes are disposed on the same plane in a grid that defines a plurality of individual capacitive sensing pixels arranged in rows and columns.

9. The input device of claim 1, wherein the first sensor electrode comprises one of a circular, rectangular, diamond, star, square, nonconvex, convex, nonconcave concave shape.

10. The input device of claim 1, wherein the processing system is configured to perform determine a change in capacitive coupling between the driven sensor electrode and the input object in a hover detection mode and in a touch detection mode, wherein, when operating in the hover detection mode, the modulated signal is driven on the first sensor electrode and, when operating in the touch detection mode, the modulated signal is driven on the second sensor electrode.

11. A method for performing capacitive sensing comprising a plurality of sensor electrodes that establish a sensing region of the input device, the method comprising:

performing absolute capacitive sensing during a first time period by driving a modulated signal on at least one of a first sensor electrode of the plurality of sensor electrodes and a second sensor electrode of the plurality of sensor electrodes to determine a change in absolute capacitance between the driven sensor electrode and an input object, wherein the first and second sensor electrodes are disposed on a same plane in the display device, and

performing transcapacitance sensing during a second time period by driving a transmitter signal onto the first sensor electrode and measuring a resulting signal on the second sensor electrode.

12. The method of claim 11, wherein the second sensor electrode at least partially encircles the first sensor electrode within the same plane.

13. The method of claim 11, wherein a plan area of the first sensor electrode is larger than a plan area of the second sensor electrode.

14. The method of claim 11, wherein a third sensor electrode of the plurality of sensor electrodes is disposed on the same plane and at least partially encircles both the first and second sensors.

15. The method of claim 14, wherein performing absolute capacitive sensing comprises:

driving a guarding signal on at least one of the first, second, and third sensor electrodes, and

driving a substantially constant voltage on at least one of the first, second and third sensor electrodes.

16. The method of claim 14, wherein performing transcapacitance sensing comprises driving one of a guarding signal or a substantially constant voltage on the third sensor electrode.

17. The method of claim 11, wherein the plurality of sensor electrodes are disposed on the same plane in a grid that defines a plurality of individual capacitive sensing pixels arranged in rows and columns.

18. The method of claim 11, wherein performing absolute capacitive sensing comprising operating in at least one of a hover detection mode and a touch detection mode,

wherein, when operating in the hover detection mode, the modulated signal is driven on the first sensor electrode and, when operating in the touch detection mode, the modulated signal is driven on the second sensor electrode.

19. A processing system for a capacitive sensing device comprising a sensing region, the processing system comprising:

a sensor module coupled to a plurality of sensor electrodes, the sensor module configured to;

perform a first mode of capacitive sensing during a first time period by driving a modulated signal on at least one of a first sensor electrode of the plurality of sensor electrodes and a second sensor electrode of the plurality of sensor electrodes, and

perform a second, different mode of capacitive sensing during a second time period using at least one of the first and second sensor electrodes,

wherein the second sensor electrode at least partially encircles the first sensor electrode.

20. The processing system of claim 19, wherein the first mode of capacitive sensing comprising determining first changes in a capacitive coupling between the driven sensor electrode and an input object,

wherein the second mode of capacitive sensing comprises driving the first sensor electrode and receiving with the second sensor electrode to determine second changes in capacitive coupling between the first sensor electrode and the second sensor electrode,

wherein a determining module in the processing system is configured to determine first positional information for an input object based on the first changes in the capacitive coupling and second positional information for the input object based on the second changes in the capacitive coupling.

21. The input device of claim 19, wherein the first electrode is disposed on a first plane and the second electrode is disposed on a second, different plane, wherein a third sensor electrode of the plurality of sensor electrodes at least partially encircles both the first and second sensor electrodes.