Modulated power supply for reduced parasitic capacitance

• US 8,766,950 B1
• Filed: 09/30/2013
• Issued: 07/01/2014
• Est. Priority Date: 09/30/2013
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Morein, Stephen L., Reynolds, Joseph Kurth
• Primary Examiner(s): HALEY, JOSEPH R
• Application Number:
  US14/042,694
• Time in Patent Office: 274 Days
• Field of Search: None
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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 3/0443 using a single layer of sensing electrodes

Abstract

Embodiments described herein include an input device for capacitive sensing. The input device includes a plurality of sensor electrodes, a modulated power supply, a plurality of analog front end channels, and a sensor module. The modulated power supply is configured to generate a modulated reference signal. The plurality of analog front end channels are coupled to the plurality of sensor electrodes and to the modulated power supply and are configured to flow charge in response to an input object in a sensing area associated with the plurality of sensor electrodes. The sensor module comprises transmitter circuitry that is coupled to the plurality of sensor electrodes and to the plurality of analog front end channels. The sensor module is configured to drive the plurality of sensor electrodes with a modulated sensor electrode signal that is based on the modulated reference signal, via the plurality of analog front end channels.

Claims

1. An input device comprising a display device having an integrated capacitive sensing device, the input device further comprising:

a plurality of source driver electrodes;

a plurality of gate electrodes;

a plurality of sensor electrodes, wherein each sensor electrode of the plurality of sensor electrode comprises one or more common electrodes of a plurality of common electrodes the plurality of common electrodes configured to be driven for display updating and input sensing; and

a processing system coupled to the plurality of source driver electrodes, the plurality of gate electrodes and the plurality of sensor electrodes, wherein the processing system is configured to;

drive a first sensor electrode and a second sensor electrode of the plurality of sensor electrodes with a first modulated signal during a first period to determine changes in capacitive coupling between the first sensor electrode and the second sensor electrode and an input object;

drive a first gate electrode of the plurality of gate electrode with a second modulated signal during a second period and

drive a first source driver electrode of the plurality of source driver electrodes with a third modulated signal during a third period, wherein the first period, the second period and the third period at least partially overlap and wherein the first modulated signal, the second modulated signal and the third modulated signal are based on a modulated reference signal.

2. The input device of claim 1, wherein the first gate electrode is driven with the second modulated signal during the second period to guard the first sensor electrode and the second sensor electrode from the first gate electrode.

3. The input device of claim 1, wherein the first source driver electrode is driven with the third modulated signal during the third period to guard the first sensor electrode and the second sensor electrode from the first source driver electrode.

4. The input device of claim 1, wherein the first gate electrode is driven with the second modulated signal during the second period to select a pixel row of the display device for updating and wherein the first source driver electrode is driven with the third modulated during the third period to update a pixel value of a pixel of the selected pixel row.

5. The input device of claim 1, the processing system comprises a capacitive sensing controller coupled with a power supply, wherein the capacitive sensing controller is configured to provide the power supply with the modulated reference signal and wherein the power supply is configured provide the first modulated signal, the second modulated signal and the third modulated signal.

6. The input device of claim 1, the input device further comprising a timing controller coupled with a power supply, wherein the timing controller is configured to provide the power supply with the modulated reference signal and wherein the power supply is configured to provide the first modulated signal, the second modulated signal and the third modulated signal.

7. The input device of claim 5, wherein the power supply is selected from a group consisting of an isolated power supply and a non-isolated power supply.

8. The input device of claim 1, wherein the processing system is further configured to determine positional information of the input object in a sensing region of the input device based on the changes in capacitive coupling.

9. The input device of claim 1 further comprising a grid electrode disposed between the first sensor electrode and the second sensor electrode, wherein the grid electrode is configured to guard the first sensor electrode and the second sensor electrode.

10. The input device of claim 1, wherein the processing system comprises:

a source driver configured to drive the first source driver electrode with the third modulated signal during the third period to update a pixel value of a pixel of a selected pixel row; and

a capacitive sensing integrated circuit configured to drive the first sensor electrode and the second sensor electrode with the first modulated signal during the first period to determine changes in capacitive coupling between the first sensor electrode and the second sensor electrode and an input object.

11. The input device of claim 10, wherein the display driver integrated circuit is synchronized with the capacitive sensing integrated circuit.

12. The input device of claim 1, wherein the processor comprises an integrated circuit configured to:

drive the first source driver electrode with the third modulated signal during the third period to update the pixel value of the pixel of a selected pixel row; and

drive the first sensor electrode and the second sensor electrode with the first modulated signal during the first period to determine changes in capacitive coupling between the first sensor electrode and the second sensor electrode and an input object.

13. A method for capacitive sensing, the method comprising:

driving a first sensor electrode and a second sensor electrode of a plurality of sensor electrodes with a first modulated signal during a first period to determine changes in capacitive coupling between the first sensor electrode and the second sensor electrode and an input object;

driving a first gate electrode of a plurality of gate electrodes with a second modulated signal during a second period; and

driving a first source driver electrode of a plurality of source driver electrodes with a third modulated signal during a third period, wherein the first period, the second period and the third period at least partially overlap and wherein the first modulated signal, the second modulated signal and the third modulated signal are based on a modulated reference signal.

14. The method of claim 13, wherein the first gate electrode is driven with the second modulated during the second period to guard the first sensor electrode and the second sensor electrode from the first gate electrode and wherein the first source driver electrode is driven with the third modulated during the third period to guard the first sensor electrode and the second sensor electrode from the first source driver electrode.

15. The method of claim 13, wherein the first gate electrode is driven with the second modulated during the second period to select a pixel row of the display device for updating and wherein the first source driver electrode is driven with the third modulated signal during the third period to update a pixel value of a pixel of the selected pixel row.

16. The method of claim 13, further comprising providing a power supply with a modulated reference signal and wherein the power supply is configured provide the first modulated signal, the second modulated signal and the third modulated signal.

17. The method of claim 13, further comprising determining positional information of the input object in a sensing region of the input device based on the changes in capacitive coupling between the first sensor electrode and the second sensor electrode and an input object.

18. A processing system for a display device comprising an integrated input sensing device, the processing system comprising:

a timing controller coupled to a power supply and configured to provide a modulated reference signal to the power supply;

a sensor module coupled to a plurality of sensor electrodes and configured to drive a first sensor electrode and a second sensor electrode of the plurality of sensor electrodes with a first modulated signal during a first period to determine changes in capacitive coupling between the first sensor electrode and the second sensor electrode and an input object;

gate select logic coupled to a plurality of gate electrodes and configured to drive a first gate electrode with a second modulated signal onto the first gate electrode during a second period; and

a source driver coupled to a plurality source driver electrodes and configured to drive a first source driver electrode of the plurality of source driver electrodes with a third modulated signal during a third period, wherein the first period, the second period and the third period at least partially overlap, and wherein the first modulated signal, the second modulated signal and the third modulated signal are based on the modulated reference signal.

19. The processing system of claim 18, wherein the first gate electrode is driven with the second modulated signal during the second period to guard the first sensor electrode and the second sensor electrode from the first gate electrode and wherein the first source driver electrode is driven with the third modulated signal during the third period to guard the first sensor electrode and the second sensor electrode from the first source driver electrode.

20. The processing system of claim 18, wherein the first gate electrode is driven with the second modulated during to select a pixel row of the display device for updating and wherein the first source driver electrode is driven with the third modulated signal during the third period to update a pixel value of a pixel of the selected pixel row.

21. The processing system of claim 18, wherein the power supply is selected from the group consisting of an isolated power supply and a non-isolated power supply.

22. The processing system of claim 18, wherein the processing system is further configured to determine positional information of the input object in a sensing region of the input device based on the changes in capacitive coupling.

23. A processing system for a display device comprising an integrated input sensing device, the processing system comprising:

a sensor module coupled to a power supply and configured to provide a modulated reference signal to the power supply, wherein the sensor module is further coupled to a plurality of sensor electrodes and configured to drive a first sensor electrode and a second sensor electrode of the plurality of sensor electrodes with a first modulated signal during a first period to determine changes in capacitive coupling between the first sensor electrode and the second sensor electrode and an input object;

gate select logic coupled to a plurality of gate electrodes and configured to drive a first gate electrode with a second modulated signal onto the first gate electrode during a second period; and

a source driver coupled to a plurality source driver electrodes and configured to drive a first source driver electrode of the plurality of source driver electrodes with a third modulated signal during a third period;

wherein the first period, the second period and the third period at least partially overlap, and wherein the first modulated signal, the second modulated signal and the third modulated signal are based on the modulated reference signal.

24. The processing system of claim 23, wherein the first gate electrode is driven with the second modulated signal during the second period to guard the first sensor electrode and the second sensor electrode from the first gate electrode and wherein the first source driver electrode is driven with the third modulated signal during the third period to guard the first sensor electrode and the second sensor electrode from the first source driver electrode.

25. The processing system of claim 23, wherein the first gate electrode is driven with the second modulated signal during the second period to select a pixel row of the display device for updating and wherein the first source driver electrode is driven with the third modulated signal during the third period to update a pixel value of a pixel of the selected pixel row.

26. The processing system of claim 23, wherein the power supply is selected from the group consisting of an isolated power supply and a non-isolated power supply.

27. The processing system of claim 23, wherein the processing system is further configured to determine positional information of the input object in a sensing region of the input device based on the changes in capacitive coupling.