Dynamic voltage generation for touch-enabled displays

• US 9,164,606 B2
• Filed: 07/31/2012
• Issued: 10/20/2015
• Est. Priority Date: 06/08/2012
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Krah, Christoph H., Bi, Yafei, White, Kevin J.
• Primary Examiner(s): Sim, Yong H
• Application Number:
  US13/563,412
• Publication Number:
  US 20130328824A1
• Time in Patent Office: 1,176 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

The disclosed embodiments relate to a system that provides power for a touch-enabled display, wherein the touch-enabled display cycles between a display mode and a touch mode. During the display mode, the system drives a display-mode voltage to the touch-enabled display through a power output, wherein the power output is coupled through a display-mode capacitor C_D to ground. Next, during a transition from the display mode to the touch mode, the system couples the power output through a touch-mode capacitor C_T to ground, wherein C_T was previously charged to a touch-mode voltage, which causes the power output to rapidly transition to the touch-mode voltage. Then, during the touch mode, the system drives the touch-mode voltage through the power output.

Claims

1. A method for providing power for a touch-enabled display, wherein the touch-enabled display cycles between a display mode and a touch mode, the method comprising:

during the display mode, driving a display-mode voltage to the touch-enabled display through a power output, wherein the power output is coupled through a display-mode capacitor C_D to ground;

during a transition from the display mode to the touch mode, coupling the power output through a touch-mode capacitor C_T to ground, wherein C_T was previously charged to a touch-mode voltage, wherein coupling the power output through the touch-mode capacitor C_T to ground causes a voltage transition at both terminals of the touch-mode capacitor C_T, at least one terminal of the display-mode capacitor C_D, and the power output; and

during the touch mode, driving the touch-mode voltage through the power output.

2. The method of claim 1, wherein during a transition between the touch mode and the display mode, the method further comprises uncoupling C_T from between the power output and ground.

3. The method of claim 2, wherein during the touch mode, the method further comprises using an auxiliary power source to charge the uncoupled touch-mode capacitor C_T to the touch-mode voltage.

4. The method of claim 1,

wherein during the touch mode, C_T is coupled in parallel with C_D between the power output and ground;

and

wherein the capacitance on C_T is larger than the capacitance on C_D, so that C_T dominates C_D during the touch mode.

5. The method of claim 1, wherein during the transition between the display mode and the touch mode, C_D is uncoupled from between the power output and ground.

6. The method of claim 1,

wherein the power output is a low output which provides a low display-mode voltage during the display mode and a low touch-mode voltage during the touch mode;

and

wherein the low output is associated with a high output which provides a high display-mode voltage during the display mode and a high touch-mode voltage during the touch mode.

7. The method of claim 6, wherein the method further comprises:

during the display mode, driving a high display-mode voltage to the touch-enabled display through the high output, wherein the high output is coupled through a high-voltage display-mode capacitor C_HD to ground;

during the transition from the display mode to the touch mode, coupling the high output through a high-voltage touch-mode capacitor C_HT to ground, wherein C_HT was previously charged to a high touch-mode voltage, thereby causing the high output to rapidly transition to the high touch-mode voltage; and

during the touch mode, driving the high touch-mode voltage through the high output.

8. The method of claim 1, wherein driving the display-mode and touch-mode voltages through the power output involves using a charge pump to drive the display-mode and touch-mode voltages.

9. An apparatus that provides power for a touch-enabled display, comprising:

a controller for the touch-enabled display configured to cycle between a display mode and a touch mode, wherein the controller is configured to provide power to the touch-enabled display through a power output, wherein during the display mode, the controller drives a display-mode voltage through the power output, and during the touch mode, the controller drives the touch-mode voltage through the power output;

a display-mode capacitor C_D coupled between the power output and ground; and

a touch-mode capacitor C_T configured to be selectively coupled between the power output and ground;

wherein during a transition from the display mode to the touch mode, the controller is configured to couple the power output through C_T to ground, wherein C_T was previously charged to a touch-mode voltage, wherein coupling the power output through the touch-mode capacitor C_T to ground causes a voltage transition at both terminals of the touch-mode capacitor C_T, at least one terminal of the display-mode capacitor C_D, and the power output.

10. The apparatus of claim 9, wherein during a transition from the touch mode to the display mode, the controller is configured to uncouple C_T from between the power output and ground.

11. The apparatus of claim 10, wherein during the touch mode, the controller is configured to use an auxiliary power source to charge C_T to the touch-mode voltage.

12. The apparatus of claim 9,

wherein during the touch mode, C_T is coupled in parallel with C_D between the power output and ground;

and

wherein the capacitance on C_T is larger than the capacitance on C_D, so that C_T dominates C_D during the touch mode.

13. The apparatus of claim 9,

wherein during the transition between the touch mode and the display mode, the controller is configured to couple C_D between the power output and ground;

and

wherein during the transition between the display mode and the touch mode, the controller is configured to uncouple C_D from between the power output and ground.

14. The apparatus of claim 9,

wherein the power output is a low power output which provides a low display-mode voltage during the display mode and a low touch-mode voltage during the touch mode;

wherein the display-mode capacitor C_D is a low-voltage display-mode capacitor C_LD; and

wherein the touch-mode capacitor C_T is a low-voltage touch-mode capacitor C_LT.

15. The apparatus of claim 13, further comprising:

a high power output from the controller;

a high-voltage display-mode capacitor C_HD coupled between the high power output and ground; and

a high-voltage touch-mode capacitor C_HT configured to be selectively coupled between the high power output and ground;

wherein during the transition from the touch mode to the display mode, the controller is configured to uncouple C_HT from between the high power output and ground;

wherein during the display mode, the controller is configured to drive a high display-mode voltage through the high power output;

wherein during a transition from the display mode to the touch mode, the controller is configured to couple the high power output through C_HT to ground, wherein C_HT was previously charged to a touch-mode voltage, thereby causing the high power output to rapidly transition to the high touch-mode voltage; and

wherein during the touch mode, the controller is configured to drive the high touch-mode voltage through the high power output.

16. The apparatus of claim 9, wherein driving the display-mode and touch-mode voltages through the power output involves using a charge pump to drive the display-mode and touch-mode voltages.

17. A touch-enabled display, comprising:

a touch screen comprising a plurality of display pixels;

a display system that updates the display pixels during a display mode;

a touch sensing system that senses touches on the touch screen during a touch mode;

a controller for the touch-enabled display configured to cycle between the display mode and the touch mode, wherein the controller is configured to provide power to the touch-enabled display through a power output, wherein during the display mode, the controller is configured to drive a display-mode voltage through the power output, and during the touch mode, the controller is configured to drive the touch-mode voltage through the power output;

a display-mode capacitor C_D coupled between the power output and ground; and

a touch-mode capacitor C_T configured to be selectively coupled between the power output and ground;

wherein during a transition from the display mode to the touch mode, the controller is configured to couple the power output through C_T to ground, wherein C_T was previously charged to a touch-mode voltage, wherein coupling the power output through the touch-mode capacitor C_T to ground causes a voltage transition at both terminals of the touch-mode capacitor C_T, at least one terminal of the display-mode capacitor C_D, and the power output.

18. The touch-enabled display of claim 17, wherein during a transition from the touch mode to the display mode, the controller is configured to uncouple C_T from between the power output and ground.

19. The touch-enabled display of claim 18, wherein during the touch mode, the controller is configured to use an auxiliary power source to charge C_T to the touch-mode voltage.

20. The touch-enabled display of claim 17,

wherein during the touch mode, C_T is coupled in parallel with C_D between the power output and ground;

and

wherein the capacitance on C_T is larger than the capacitance on C_D, so that C_T dominates C_D during the touch mode.

21. The touch-enabled display of claim 17,

wherein during the transition between the touch mode and the display mode, the controller is configured to couple C_D between the power output and ground;

and

wherein during the transition between the display mode and the touch mode, the controller is configured to uncouple C_D from between the power output and ground.

22. The touch-enabled display of claim 17,

wherein the power output is a low power output which provides a low display-mode voltage during the display mode and a low touch-mode voltage during the touch mode;

wherein the display-mode capacitor C_D is a low-voltage display-mode capacitor C_LD; and

wherein the touch-mode capacitor C_T is a low-voltage touch-mode capacitor C_LT.

23. The touch-enabled display of claim 22, further comprising:

a high power output from the controller;

a high-voltage display-mode capacitor C_HD coupled between the high power output and ground; and

a high-voltage touch-mode capacitor C_HT configured to be selectively coupled between the high power output and ground;

wherein during the transition from the touch mode to the display mode, the controller is configured to uncouple a C_HT from between the high power output and ground;

wherein during the display mode, the controller is configured to drive a high display-mode voltage through the high power output;

wherein during a transition from the display mode to the touch mode, the controller is configured to couple the high power output through C_HT to ground, wherein C_HT was previously charged to a touch-mode voltage, thereby causing the high power output to rapidly transition to the high touch-mode voltage; and

wherein during the touch mode, the controller is configured to drive the high touch-mode voltage through the high power output.

24. The touch-enabled display of claim 23, wherein driving the display-mode and touch-mode voltages through the power output involves using a charge pump to drive the display-mode and touch-mode voltages.