MULTI-MODE VOLTAGES FOR TOUCHSCREENS

• US 20160195991A1
• Filed: 01/29/2016
• Published: 07/07/2016
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: YOUSEFPOR, Marduke, WHITE, Kevin J.
• Granted Patent: US 9,939,950 B2
• Time in Patent Office: Days
• 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 and a touch screen component, the touch screen component associated with an operating capacitance, the operating capacitance being between a first part of the touch screen component and a second part of the touch screen component;

a multi-mode power system configured to;

operate the touch screen in a first voltage mode, the first voltage mode corresponding to a display phase, the selection of the first voltage mode resulting in a value of the operating capacitance varying within a first portion of a characteristic capacitance curve of the touch screen component, and

operate the touch screen in a second voltage mode, the second voltage mode corresponding to a touch sensing phase, the selection of the second voltage mode resulting in the value of the operating capacitance varying within a second portion, different from the first portion, of the characteristic capacitance curve 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 mode is applied at 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 mode is applied at the touch screen during the sensing of touch.

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

the touch screen component is a pixel transistor associated with a display pixel of the plurality of display pixels, and

the first part is a drain of the pixel transistor.

3. The integrated touch screen device of claim 2, wherein:

the first voltage mode applies a first and second voltage to the pixel transistor, and

the second voltage mode applies a third and fourth voltage to the pixel transistor,

the first and third voltages associated with an on state of the pixel transistor, and the second and fourth voltages associated with an off state of the pixel transistor, the third and fourth voltages different from the first and second voltages.

4. The integrated touch screen device of claim 3, wherein the first, second, third, and fourth voltages correspond to first, second, third, and fourth capacitance values of the operating capacitance, the first, second, third and fourth capacitance values being values on the characteristic capacitance curve of the pixel transistor.

5. The integrated touch screen device of claim 1, wherein the first voltage mode varies a voltage applied to the touch screen component, the value of the operating capacitance being within the first portion of the characteristic capacitance curve of the touch screen component based on the varying of the voltage in the first voltage mode, and

the second voltage mode varies the voltage applied to the touch screen component, the value of the operating capacitance being within the first portion of the characteristic capacitance curve of the touch screen component based on the varying of the voltage in the second voltage mode.

6. The integrated touch screen device of claim 1, wherein the operating capacitance is a voltage-dependent capacitance between the first part and the second part of the touch screen component.

7. The integrated touch screen device of claim 6, wherein the touch screen component is included in a display pixel of the plurality of display pixels.

8. The integrated touch screen device of claim 2, wherein the second part is a gate of the pixel transistor.

9. The integrated touch screen device of claim 2, wherein the second part is a source of the pixel transistor.

10. The integrated touch screen device of claim 1, wherein the second portion of the capacitance curve contains a local minimum.

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

the touch screen component is a pixel transistor associated with a display pixel of the plurality of display pixels, and

the first part is a gate of the pixel transistor.

12. The integrated touch screen device of claim 1, wherein varying the value of the operating capacitance within the second portion of the characteristic capacitance curve of the touch screen component results in a first amount of noise in a touch signal sensed at the touch screen,

and varying the operating capacitance within the first portion of the characteristic capacitance curve of the touch screen component results in a second amount of noise in the touch signal, the first amount of noise less than the second amount of noise.

13. A method comprising:

operating a touch screen including a plurality of display pixels in a first voltage mode, the first voltage mode corresponding to a display phase, the selection of the first voltage mode resulting in a value of the operating capacitance varying within a first portion of a characteristic capacitance curve of the touch screen component, and

operating the touch screen in a second voltage mode, the second voltage mode corresponding to a touch sensing phase, the selection of the second voltage mode resulting in the value of the operating capacitance varying within a second portion, different from the first portion, of the characteristic capacitance curve of the touch screen component;

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

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

14. The method of claim 13, wherein:

the touch screen component is a pixel transistor associated with a display pixel of the plurality of display pixels, and

the first part is a drain of the pixel transistor.

15. The method of claim 14, wherein:

the first voltage mode applies a first and second voltage to the pixel transistor, and

the second voltage mode applies a third and fourth voltage to the pixel transistor,

the first and third voltages associated with an on state of the pixel transistor, and the second and fourth voltages associated with an off state of the pixel transistor, the third and fourth voltages different from the first and second voltages.

16. The method of claim 15, wherein the first, second, third, and fourth voltages correspond to first, second, third, and fourth capacitance values of the operating capacitance, the first, second, third and fourth capacitance values being values on the characteristic capacitance curve of the pixel transistor.

17. The method of claim 13, wherein the first voltage mode varies a voltage applied to the touch screen component, the value of the operating capacitance being within the first portion of the characteristic capacitance curve of the touch screen component based on the varying of the voltage in the first voltage mode, and

the second voltage mode varies the voltage applied to the touch screen component, the value of the operating capacitance being within the first portion of the characteristic capacitance curve of the touch screen component based on the varying of the voltage in the second voltage mode.

18. The method of claim 13, wherein the operating capacitance is a voltage-dependent capacitance between the first part and the second part of the touch screen component.

19. The method of claim 18, wherein the touch screen component is included in a display pixel of the plurality of display pixels.

20. The method of claim 14, wherein the second part is a gate of the pixel transistor.

21. The method of claim 14, wherein the second part is a source of the pixel transistor.

22. The method of claim 13, wherein the second portion of the capacitance curve contains a local minimum.

23. The method of claim 13, wherein:

the touch screen component is a pixel transistor associated with a display pixel of the plurality of display pixels, and

the first part is a gate of the pixel transistor.

24. The method of claim 13, wherein varying the value of the operating capacitance within the second portion of the characteristic capacitance curve of the touch screen component results in a first amount of noise in a touch signal sensed at the touch screen,

and varying the operating capacitance within the first portion of the characteristic capacitance curve of the touch screen component results in a second amount of noise in the touch signal, the first amount of noise less than the second amount of noise.

25. A non-transitory computer-readable storage medium having stored therein instructions, which when executed by a processor cause the processor to perform a method comprising:

operating a touch screen including a plurality of display pixels in a first voltage mode, the first voltage mode corresponding to a display phase, the selection of the first voltage mode resulting in a value of the operating capacitance varying within a first portion of a characteristic capacitance curve of the touch screen component, and

operating the touch screen in a second voltage mode, the second voltage mode corresponding to a touch sensing phase, the selection of the second voltage mode resulting in the value of the operating capacitance varying within a second portion, different from the first portion, of the characteristic capacitance curve of the touch screen component;

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

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