Capacitive sensing during non-display update times

Patent metadata

Field	Value
Publication number	US-9576558-B2
Application number	US-201514641040-A
Country	US
Kind code	B2
Filing date	Mar 6, 2015
Priority date	Sep 7, 2011
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

Embodiments of the invention generally provide an input device with display screens that periodically update (refresh) the screen by selectively driving common electrodes corresponding to pixels in a display line. In general, the input devices drive each electrode until each display line (and each pixel) of a display frame is updated. In addition to updating the display, the input device may perform capacitive sensing using the display screen as a proximity sensing area. To do this, the input device may interleave periods of capacitive sensing between periods of updating the display based on a display frame. For example, the input device may update the first half of display lines of the display screen, pause display updating, perform capacitive sensing, and finish updating the rest of the display lines. Further still, the input device may use common electrodes for both updating the display and performing capacitive sensing.

First claim

What is claimed is:

1. A processing system for a display device comprising an integrated capacitive sensing device, the processing system comprising:
a display driver module comprising driver circuitry, the display driver module configured to be coupled to a plurality of common electrodes configured to be driven for updating a plurality of display lines in a display screen of the display device and performing capacitive sensing, wherein the display driver module is configured to drive a first one of the plurality of common electrodes for updating a first one of the plurality of display lines during a first time period of a first display frame and drive a second one of the plurality of common electrodes for updating a second one of the plurality of display lines during a second time period of the first display frame; and
a touch driver module configured to drive a first sensor electrode for capacitive sensing during a third time period of the first display frame, the first sensor electrode comprising at least one common electrode of the plurality of common electrodes, and the third time period being at least as long as the first time period and occurring after the first time period and before the second time period.

2. The processing system of claim 1 , wherein the first sensor electrode comprises the first common electrode.

3. The processing system of claim 1 , wherein the third time period is longer than the first time period.

4. The processing system of claim 1 , wherein driving the first sensor electrode for capacitive sensing during the third time period comprises driving the first sensor electrode with a sensing signal comprising a plurality of contiguous sensing cycles.

5. The processing system of claim 1 , wherein driving the first sensor electrode for capacitive sensing during the third time period comprises driving the first sensor electrode for absolute capacitance.

6. The processing system of claim 1 , wherein the first sensor electrode is one of a plurality of sensor electrodes, and wherein the plurality of sensor electrodes is disposed in an array of rectangles.

7. The processing system of claim 1 , wherein driving the first sensor electrode for capacitive sensing during the third time period comprises driving the first sensor electrode with a transmitter signal and wherein the processing system further comprises a receiver module coupled to a second sensor electrode, wherein the receiver module is configured to receive resulting signals with the second sensor electrode.

8. The processing system of claim 1 , wherein the display driver module is further configured to:
drive a second sensor electrode for capacitive sensing during a fourth time period of the first display frame, the fourth time period being at least as long as the second time period and occurring after the second time period and before all of the plurality of display lines have been updated during the first display frame.

9. The processing system of claim 1 , further comprising a determination module configured to:
determine positional information for an input object based on resulting signals acquired when the first sensor electrode is driven for capacitive sensing; and
acquire a measurement of interference, wherein the first sensor electrode is driven during the third time period with a first sensing signal having a first signal frequency and wherein the touch driver module is further configured to shift from driving the first sensing signal having the first signal frequency to driving a second sensing signal having a second signal frequency based on the measurement of interference.

10. The processing system of claim 1 , wherein the touch driver module is configured to:
drive the first sensor electrode for capacitive sensing during a fourth time period of the first display frame, the fourth time period occurring after the second time period and before all of the plurality of display lines have been updated during the first display frame.

11. The processing system of claim 1 , wherein the touch driver module is further configured to:
drive a second sensor electrode for capacitive sensing during the third time period of the first display frame, the second sensor electrode comprising a second at least one of the plurality of common electrodes, and wherein the first sensor electrode and the second sensor electrode are simultaneously driven.

12. A method for operating a capacitive sensing device, the method comprising:
driving a first common electrode of a plurality of common electrodes for updating, during a first time period, a first display line of a first display frame;
driving a second common electrode of the plurality of common electrodes for updating, during a second time period, a second display line of the first display frame; and
driving a first sensor electrode for capacitive sensing during a third time period of the first display frame, the first sensor electrode comprising at least one common electrode of the plurality of common electrodes, and the third time period being at least as long as the first time period and occurring after the first time period and before the second time period.

13. The method of claim 12 , wherein the step of driving the first sensor electrode further comprises:
driving the first sensor electrode with a sensing signal comprising a plurality of contiguous sensing cycles.

14. The method of claim 12 , wherein driving the first sensor electrode for capacitive sensing during the third time period comprises:
driving the first sensor electrode for absolute capacitance.

15. The method of claim 12 , wherein driving the first sensor electrode for capacitive sensing during the third time period comprises:
driving the first sensor electrode with a transmitter signal and wherein the method further comprises receiving resulting signals with a second sensor electrode.

16. The method of claim 12 , further comprising:
driving the first sensor electrode for capacitive sensing during a fourth time period of the first display frame, the fourth time period occurring after the second time period and before all display lines have been updated during the first display frame.

17. The method of claim 12 , further comprising:
driving a second sensor electrode for capacitive sensing during a fourth time period of the first display frame, the fourth time period being at least as long as the second time period and occurring after the second time period and before all display lines have been updated during the first display frame.

18. A display device having an integrated capacitive sensing device, the display device comprising:
a plurality of common electrodes configured to be driven for updating a plurality of display lines of a display screen of the display device and performing capacitive sensing;
a plurality of receiver electrodes; and
a processing system coupled to the plurality of common electrodes and to the plurality of receiver electrodes, wherein the processing system is configured to:
drive a first one of the plurality of common electrodes for updating, during a first time period of a first display frame, a first one of the plurality of display lines and a second common electrode of the plurality of common electrodes for updating, during a second time period of the first display frame, a second one of the plurality of display lines;
drive a first sensor electrode for capacitive sensing during a third time period of the first display frame, the first sensor electrode comprising at least one common electrode of the plurality of common electrodes

Assignees

• Synaptics Inc

Inventors

• Shepelev Petr
• Schwartz Adam

Classifications

• G06F3/0412 Primary

  Digitisers structurally integrated in a display · CPC title

• G06F3/044

  by capacitive means · CPC title

• G09G5/18 Primary

  Timing circuits for raster scan displays (specially adapted for television H04N {; synchronisation between the display unit and other display units, videodisc player G09G5/12}) · CPC title

• G06F3/0416 Primary

  Control or interface arrangements specially adapted for digitisers · CPC title

• G06F3/04184

  Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally · CPC title