Multi-mode voltages for touchscreens

• US 9,268,427 B2
• Filed: 09/23/2011
• Issued: 02/23/2016
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Yousefpor, Marduke, White, Kevin J.
• Primary Examiner(s): Eisen, Alexander
• Assistant Examiner(s): Yang, Nan-Ying
• Application Number:
  US13/244,031
• Publication Number:
  US 20130076647A1
• Time in Patent Office: 1,614 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• 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 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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

Abstract

Operating touch screens by applying more than one voltage modes, including a first voltage mode corresponding to a display phase and a second voltage mode corresponding to a touch sensing phase, is provided. An integrated touch screen device can include a multi-mode power system that can select a first voltage mode corresponding a display phase and a second voltage mode corresponding to a touch sensing phase. Each of one or more voltages can be applied to the touch screen at the corresponding first voltage level during the updating of the image. A touch sensing system can sense touch during a touch sensing phase. Each of one or more voltages can be applied to the touch screen at the corresponding second voltage level during the sensing of touch.

Claims

1. An integrated touch screen device comprising:

a touch screen including a plurality of display pixels;

a multi-mode power system configured to;

select a first voltage, the first voltage corresponding to a display phase, the selection of the first voltage resulting in a touch screen component operating at a first capacitance and at a second capacitance, the first capacitance being less than a third capacitance of the touch screen component, and the second capacitance being greater than the third capacitance, the third capacitance being between the first capacitance and the second capacitance on a capacitance curve of the touch screen component, wherein the first, second and third capacitances are between a first part and a second part of the touch screen component, and

select a second voltage, the second voltage corresponding to a touch sensing phase, the second voltage being different than the first voltage, the selection of the second voltage resulting in the touch screen component operating at a fourth capacitance and at a fifth capacitance, the fourth capacitance and the fifth capacitance being greater than a sixth capacitance of the touch screen component, the sixth capacitance being between the fourth capacitance and the fifth capacitance on the capacitance curve of the touch screen component, wherein the fourth, fifth and sixth capacitances are between the first part and the second part of the touch screen component;

a display system configured to update an image displayed by the display pixels during the display phase, wherein the first voltage is applied to the touch screen during the updating of the image; and

a touch sensing system configured to sense touch during the touch sensing phase, wherein the second voltage is applied to the touch screen during the sensing of touch.

2. The integrated touch screen device of claim 1, wherein the first voltage and the second voltage are applied to the touch screen component.

3. The integrated touch screen device of claim 2, wherein the touch screen component has a voltage-dependent capacitance.

4. The integrated touch screen device of claim 3, wherein:

the touch screen component includes a pixel transistor of each display pixel,

the touch screen further includes a plurality of gate lines, each gate line connected to a gate of the pixel transistor in each display pixel, and

the second voltage is applied to a gate line that switches the pixel transistor to an off state.

5. The integrated touch screen device of claim 3, wherein a single voltage source applies the first voltage and the second voltage.

6. The integrated touch screen device of claim 5, wherein the single voltage source is controlled by the display system during the display phase and is controlled by the touch sensing system during the touch sensing phase.

7. The integrated touch screen device of claim 3, wherein the application of the first voltage to the touch screen component results in the first and second capacitances of the touch screen component, the application of the second voltage to the touch screen component results in the fourth and fifth capacitances of the touch screen component, and the first and second capacitances are greater than the fourth and fifth capacitances.

8. The integrated touch screen device of claim 3, the voltage dependence of the capacitance corresponding to a curve representing capacitance values versus voltage values, wherein the application of the first voltage to the touch screen component results in an operational range of the touch screen component in a first portion of the curve, the application of the second voltage to the touch screen component results in an operational range of the touch screen component in a second portion of the curve, the second portion of the curve being more linear than the first portion of the curve.

9. The integrated touch screen device of claim 3, the voltage dependence of the capacitance corresponding to a curve representing capacitance values versus voltage values, wherein the application of the first voltage to the touch screen component results in an operational range of the touch screen component in a first portion of the curve, the application of the second voltage to the touch screen component results in an operational range of the touch screen component in a second portion of the curve, wherein an average of capacitance values in the second portion of the curve is less than an average of capacitance values in the first portion of the curve.

10. The integrated touch screen device of claim 9, wherein the touch screen component includes a pixel transistor in each display pixel, the capacitance value includes a gate-to-drain capacitance of the pixel transistor, and the application of the second voltage to the pixel transistor sets the gate-to-drain capacitance of the pixel transistor to a minimum capacitance of the curve.

21. The integrated touch screen device of claim 1, wherein the first and second voltages comprise gate line voltages applied to a gate line of a pixel transistor in a first display pixel of the plurality of display pixels.

23. The integrated touch screen device of claim 1, wherein the first, second, third, fourth, fifth and sixth capacitances correspond to respective voltages applied across the first part and the second part of the touch screen component.

25. The integrated touch screen device of claim 1, wherein:

the touch screen component comprises a pixel transistor,

the first part of the touch screen component comprises a gate of the pixel transistor, and

the second part of the touch screen component comprises a drain of the pixel transistor.

27. The integrated touch screen device of claim 1, wherein the first, second, third, fourth, fifth and sixth capacitances are total capacitances between the first part and the second part of the touch screen component.

29. The integrated touch screen device of claim 1, wherein:

the first part of the touch screen component includes a first electrically contiguous portion,

the second part of the touch screen component includes a second electrically contiguous portion, and

the first, second, third, fourth, fifth and sixth capacitances are between the first electrically contiguous portion and the second electrically contiguous portion.

11. A method of operating an integrated touch screen device including a touch screen with a plurality of display pixels, the method comprising:

selecting a first voltage, the first voltage corresponding a display phase, the selection of the first voltage resulting in a touch screen component operating at a first capacitance and at a second capacitance, the first capacitance being less than a third capacitance of the touch screen component, and the second capacitance being greater than the third capacitance, the third capacitance being between the first capacitance and the second capacitance on a capacitance curve of the touch screen component, wherein the first, second and third capacitances are between a first part and a second part of the touch screen component;

updating an image displayed by the display pixels during the display phase, wherein the first voltage is applied to the touch screen during the updating of the image;

selecting a second voltage, the second voltage corresponding to a touch sensing phase, the second voltage being different than the first voltage, the selection of the second voltage resulting in the touch screen component operating at a fourth capacitance and at a fifth capacitance, the fourth capacitance and the fifth capacitance being greater than a sixth capacitance of the touch screen component, the sixth capacitance being between the fourth capacitance and the fifth capacitance on the capacitance curve of the touch screen component, wherein the fourth, fifth and sixth capacitances are between the first part and the second part of the touch screen component; and

sensing touch during the touch sensing phase, wherein the second voltage is applied to the touch screen during the sensing of touch.

12. The method of claim 11, wherein the first voltage and the second voltage are applied to the touch screen component.

13. The method of claim 12, wherein the touch screen component has a voltage-dependent capacitance.

14. The method of claim 13, wherein:

the touch screen component includes a pixel transistor of each display pixel,

the touch screen further includes a plurality of gate lines, each gate line connected to a gate of the pixel transistor in each display pixel, and

the second voltage is applied to a gate line that switches the pixel transistor to an off state.

15. The method of claim 13, wherein a single voltage source applies the first voltage and the second voltage.

16. The method of claim 15, wherein the single voltage source is controlled by display system during the display phase and is controlled by a touch sensing system during the touch sensing phase.

17. The method of claim 13, wherein the application of the first voltage to the touch screen component results in the first and second capacitances of the touch screen component, the application of the second voltage to the touch screen component results in the fourth and fifth capacitances of the touch screen component, and the first and second capacitances are greater than the fourth and fifth capacitances.

18. The method of claim 13, the voltage dependence of the capacitance corresponding to a curve representing capacitance values versus voltage values, wherein the application of the first voltage to the touch screen component results in an operational range of the touch screen component in a first portion of the curve, the application of the second voltage to the touch screen component results in an operational range of the touch screen component in a second portion of the curve, the second portion of the curve being more linear than the first portion of the curve.

19. The method of claim 13, the voltage dependence of the capacitance corresponding to a curve representing capacitance values versus voltage values, wherein the application of the first voltage to the touch screen component results in an operational range of the touch screen component in a first portion of the curve, the application of the second voltage to the touch screen component results in an operational range of the touch screen component in a second portion of the curve, wherein an average of capacitance values in the second portion of the curve is less than an average of capacitance values in the first portion of the curve.

20. The method of claim 19, wherein the touch screen component includes a pixel transistor in each display pixel, the capacitance value includes a gate-to-drain capacitance of the pixel transistor, and the application of the second voltage to the pixel transistor sets the gate-to-drain capacitance of the pixel transistor to a minimum capacitance of the curve.

22. The method of claim 11, wherein the first and second voltages comprise gate line voltages applied to a gate line of a pixel transistor in a first display pixel of the plurality of display pixels.

24. The method of claim 11, wherein the first, second, third, fourth, fifth and sixth capacitances correspond to respective voltages applied across the first part and the second part of the touch screen component.

26. The method of claim 11, wherein:

the touch screen component comprises a pixel transistor,

the first part of the touch screen component comprises a gate of the pixel transistor, and

the second part of the touch screen component comprises a drain of the pixel transistor.

28. The method of claim 11, wherein the first, second, third, fourth, fifth and sixth capacitances are total capacitances between the first part and the second part of the touch screen component.

30. The method of claim 11, wherein:

the first part of the touch screen component includes a first electrically contiguous portion,

the second part of the touch screen component includes a second electrically contiguous portion, and

the first, second, third, fourth, fifth and sixth capacitances are between the first electrically contiguous portion and the second electrically contiguous portion.