MULTI-MODE VOLTAGES FOR TOUCHSCREENS

• US 20130076647A1
• Filed: 09/23/2011
• Published: 03/28/2013
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Marduke Yousefpor
• Inventors: YOUSEFPOR, Marduke, White, Kevin J.
• Granted Patent: US 9,268,427 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• 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 that selects a first voltage mode corresponding a display phase, the first voltage mode including a first voltage level for each of one or more voltages of the touch screen, and selects a second voltage mode corresponding to a touch sensing phase, the second voltage mode including a second voltage level for each of the one or more voltages, each second voltage level being different than the corresponding first voltage level;

a display system that updates an image displayed by the display pixels during the display phase, wherein each of the one or more voltages are applied to the touch screen at the corresponding first voltage level during the updating of the image; and

a touch sensing system that senses touch during a touch sensing phase, wherein each of the one or more voltages are applied to the touch screen at the corresponding second voltage level during the sensing of touch.

2. The integrated touch screen device of claim 1, wherein the one or more voltages includes a voltage applied to a touch screen component with a voltage-dependent electrical characteristic.

3. The integrated touch screen device of claim 2, wherein the electrical characteristic includes a capacitance associated with the touch screen component.

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 being connected to a gate of the pixel transistor in each display pixel, and the one or more voltages includes a gate line voltage that switches the pixel transistor to an off state.

5. The integrated touch screen device of claim 3, wherein a single voltage source applies one of the one or more voltages at both the first voltage level and the second voltage level.

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 voltage to the touch screen component at the first voltage level results in a first capacitance of the touch screen component, the application of voltage to the touch screen component at the second voltage level results in a second capacitance of the touch screen component, and the second capacitance is less than the first capacitance.

8. The integrated touch screen device of claim 2, the voltage dependence of the electrical characteristic corresponding to a curve representing electrical characteristic values versus voltage values, wherein the application of voltage to the touch screen component at the first voltage level results in an operational range of the touch screen component in a first portion of the curve, the application of voltage to the touch screen component at the second voltage level 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 2, the voltage dependence of the electrical characteristic corresponding to a curve representing electrical characteristic values versus voltage values, wherein the application of voltage to the touch screen component at the first voltage level results in an operational range of the touch screen component in a first portion of the curve, the application of voltage to the touch screen component at the second voltage level results in an operational range of the touch screen component in a second portion of the curve, wherein an average of electrical characteristic values in the second portion of the curve is less than an average of electrical characteristic 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 electrical characteristic value includes a gate-to-drain capacitance of the pixel transistor, and the application of voltage to the pixel transistor at the second voltage level sets the gate-to-drain capacitance of the pixel transistor to a minimum capacitance of the curve.

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 mode corresponding a display phase, the first voltage mode including a first voltage level for each of one or more voltages of the touch screen;

updating an image displayed by the display pixels during the display phase, wherein each of the one or more voltages are applied to the touch screen at the corresponding first voltage level during the updating of the image;

selecting a second voltage mode corresponding to a touch sensing phase, the second voltage mode including a second voltage level for each of the one or more voltages, each second voltage level being different than the corresponding first voltage level; and

sensing touch during a touch sensing phase, wherein each of the one or more voltages are applied to the touch screen at the corresponding second voltage level during the sensing of touch.

12. The method of claim 11, wherein the one or more voltages includes a voltage applied to a touch screen component with a voltage-dependent electrical characteristic.

13. The method of claim 12, wherein the electrical characteristic includes a capacitance associated with the touch screen component.

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 being connected to a gate of the pixel transistor in each display pixel, and the one or more voltages includes a gate line voltage that switches the pixel transistor to an off state.

15. The method of claim 13, wherein a single voltage source applies one of the one or more voltages at both the first voltage level and the second voltage level.

16. The method of claim 15, 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.

17. The method of claim 13, wherein the application of voltage to the touch screen component at the first voltage level results in a first capacitance of the touch screen component, the application of voltage to the touch screen component at the second voltage level results in a second capacitance of the touch screen component, and the second capacitance is less than the first capacitance.

18. The method of claim 12, the voltage dependence of the electrical characteristic corresponding to a curve representing electrical characteristic values versus voltage values, wherein the application of voltage to the touch screen component at the first voltage level results in an operational range of the touch screen component in a first portion of the curve, the application of voltage to the touch screen component at the second voltage level 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 12, the voltage dependence of the electrical characteristic corresponding to a curve representing electrical characteristic values versus voltage values, wherein the application of voltage to the touch screen component at the first voltage level results in an operational range of the touch screen component in a first portion of the curve, the application of voltage to the touch screen component at the second voltage level results in an operational range of the touch screen component in a second portion of the curve, wherein an average of electrical characteristic values in the second portion of the curve is less than an average of electrical characteristic 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 electrical characteristic value includes a gate-to-drain capacitance of the pixel transistor, and the application of voltage to the pixel transistor at the second voltage level sets the gate-to-drain capacitance of the pixel transistor to a minimum capacitance of the curve.