Integrated in-plane switching display and touch sensor

A touch display system, comprising:

• a display containing a plurality of cells, each cell having a driven electrode and a counter electrode;
• a plurality of color data lines, the driven electrode of each cell being coupled to one of the plurality of color data lines;
• a plurality of counter data lines, the counter electrode of each cell being coupled to one of the plurality of counter data lines;
• and
• a plurality switching elements associated with respective counter and color data lines and controlled by a control circuit to selectively connect one or more of the plurality of counter and color data lines for operating in a display mode of operation or in touch sense mode of operation;
• wherein:
• in the display mode of operation, the driven electrode is connected to at least one color data line for driving the driven electrode and the counter electrode is connected to ground or to a voltage different from a drive voltage of the driven electrode;
• and
• in at least a part of the touch sense mode of operation, the driven and counter electrodes are connected to discharge any voltage differential therebetween.

A method for providing touch functionality for a device comprising the steps of:

• dividing the cells of a display into plurality of regions, each cell having a driven electrode and a counter electrode;
• dividing the regions into first and second type regions, each region containing one or more cells, the first type region disposed adjacent the second type region;
• driving the driven electrodes of the cells of the display with display data signals during a display update period, with the counter electrodes of the cells being grounded or set to a different voltage from that driving the driven electrodes;
• driving at least the driven electrodes of each cell of the first type regions with a stimulus signal during a touch sense period;
• connecting at least one of the driven and counter electrodes of each cell of the second type regions to a sensing circuit during the touch sense period;
• and
• alternating the display update and touch sense periods.

A touch enabled device comprising:

• a display comprising a plurality of cells, each cell having a driven electrode and a counter electrode, the cells being grouped in a plurality of regions, the regions being of a first type or a second type, each region containing one or more cells;
• a control circuit configured to,
• drive the driven electrodes of the cells of the display with display data signals during a display update period, with the counter electrodes of the cells being grounded or set to a different voltage from that driving the driven electrodes;
• drive at least the driven electrodes of each cell of the first type regions with a stimulus signal during a touch sense period;
• connect at least one of the driven and counter electrodes of each cell of the second type regions to a sensing circuit during the touch sense period;
• and
• alternate the display update and touch sense periods.

A mobile telephone including a touch display system, the touch display system comprising:

• a display containing a plurality of cells, each cell having two electrodes;
• a plurality of color data lines, a first electrode of each cell being connected to at least one of the plurality of color data lines;
• a plurality of counter data lines, a second electrode of each cell being connected to at least one of the plurality of counter data lines;
• in a display mode, the first and second electrodes operable for displaying an image on the display resulting from a difference in potential between the first and second electrodes;
• a plurality switching elements operable:
• in at least part of a sense mode, for discharging any voltage differentials between the first and second electrodes;
• and
• in another part of the sense mode, for coupling the plurality of counter and color data lines to a drive circuit for receiving a stimulation signal or to capacitance measuring circuit.

An audio player including a touch display system, the touch display system comprising:

• a display containing a plurality of cells, each cell having two electrodes;
• a plurality of color data lines, a first electrode of each cell being connected to at least one of the plurality of color data lines;
• a plurality of counter data lines, a second electrode of each cell being connected to at least one of the plurality of counter data lines;
• in a display mode, the first and second electrodes operable for displaying an image on the display resulting from a difference in potential between the first and second electrodes;
• a plurality switching elements operable:
• in at least part of a sense mode, for discharging any voltage differentials between the first and second electrodes;
• and
• in another part of the sense mode, for coupling the plurality of counter and color data lines to a drive circuit for receiving a stimulation signal or to capacitance circuit.

A touch enabled display comprising:

• a plurality of display pixels, each display pixel comprising a display pixel circuit including first and second electrodes;
• a first group of display pixels being a touch stimulus group of pixels having at least one of the first and second electrodes connectable to a stimulus signal;
• and
• a second group of display pixels being a charge sensor group of pixels having at least one of the first and second electrodes connectable to charge sensing circuitry;
• wherein:
• the touch stimulus group of pixels is disposed adjacent the charge sensor group of pixels;
• and
• the sensing circuit is configured to sense changes in the mutual capacitance between the touch stimulus group of pixels and the adjacent charge sensor group of pixels.

A mobile telephone including a touch enabled display comprising:

• a plurality of display pixels, each display pixel comprising a display pixel circuit including first and second electrodes;
• a first group of display pixels being a touch stimulus group of pixels having at least one of the first and second electrodes connectable to a stimulus signal;
• and
• a second group of display pixels being a charge sensor group of pixels having at least one of the first and second electrodes connectable to charge sensing circuitry;
• wherein:
• the touch stimulus group of pixels is disposed adjacent the charge sensor group of pixels;
• and
• the sensing circuit configured to sense changes in the mutual capacitance between the touch stimulus group of pixels and the adjacent charge sensor group of pixels.

An audio player including a touch enabled display comprising:

• a plurality of display pixels, each display pixel comprising a display pixel circuit including first and second electrodes;
• a first group of display pixels being a touch stimulus group of pixels having at least one of the first and second electrodes connectable to a stimulus signal;
• and
• a second group of display pixels being a charge sensor group of pixels having at least one of the first and second electrodes connectable to charge sensing circuitry;
• wherein:
• the touch stimulus group of pixels is disposed adjacent the charge sensor group of pixels;
• and
• the sensing circuit is configured to sense changes in the mutual capacitance between the touch stimulus group of pixels and the adjacent charge sensor group of pixels.

A method for sensing user input at a device comprising:

• providing a display comprising a plurality of display pixels, each display pixel comprising a display pixel circuit including first and second electrodes;
• providing a first group of display pixels being a touch stimulus group of pixels having at least one of the first and second electrodes connectable to a stimulus signal;
• and
• providing a second group of display pixels being a charge sensor group of pixels having at least one of the first and second electrodes connectable to charge sensing circuitry;
• disposing the touch stimulus group of pixels adjacent the charge sensor group of pixels;
• and
• sensing changes in the mutual capacitance between the touch stimulus group of pixels adjacent the charge sensor group of pixels,
• wherein the changes of the mutual capacitance are indicative of touch events at the display.