Power management for integrated touch screens

• US 9,760,195 B2
• Filed: 09/23/2011
• Issued: 09/12/2017
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Krah, Christoph Horst, White, Kevin J., Bi, Yafei
• Primary Examiner(s): Eisen, Alexander
• Assistant Examiner(s): Yang, Nan-Ying
• Application Number:
  US13/244,072
• Publication Number:
  US 20130076648A1
• Time in Patent Office: 2,181 Days
• 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 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• 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

Reducing or eliminating the effects of noise that can be generated by a power system of a touch screen device, such as a gate line voltage system that applies voltage to gate lines of the touch screen, is provided. In one example, a power supply, such as a charge pump, can be disabled during active touch sensing, such that noise from the charge pump is not generated during touch sensing. In some examples, a voltage regulator can help to maintain the gate voltage level at or above a desired threshold. In some cases, noise entering the touch sensing system can have a lasting effect on noise-sensitive components, even after the noise source is disabled. In these cases, a post-noise stabilizing system can be included to stabilize, reset, etc., noise-sensitive components of the touch sensing system, which can help to reduce or eliminate the lasting effect of noise.

Claims

1. An integrated touch screen system comprising:

a touch screen including a plurality of display pixels, the plurality of display pixels including an addressing system that includes a plurality of conductive lines;

a voltage regulator;

a driver configured to receive first voltages from the voltage regulator and apply second voltages to the conductive lines based on the received first voltages, the first voltages having a stable level;

a display system that updates an image displayed by the display pixels during a display phase, wherein the updating of the image includes actively operating a power supply to apply third voltages to the voltage regulator, and operating the driver to apply the second voltages to the conductive lines to address the display pixels; and

a touch sensing system that senses touch during a touch sensing phase, the touch sensing phase including a plurality of active sensing periods during which the touch sensing system performs active touch sensing while the power supply is not actively applying the third voltages to the voltage regulator, the touch sensing phase further including at least one gap period between active sensing periods, wherein the power supply is actively operated to apply the third voltages to the voltage regulator, and the driver is operated to apply the second voltages to the conductive lines during the at least one gap period while active touch sensing is not being performed, wherein the power supply applies the third voltages during the one or more gap periods such that the voltage regulator is able to apply the first voltages to the driver during the active sensing periods.

2. The integrated touch screen system of claim 1, wherein each display pixel includes a pixel thin-film transistor (TFT), and the conductive lines include gate lines, each pixel TFT being connected to one gate line.

3. The integrated touch screen system of claim 1, wherein the power supply includes one of a charge pump and an inductive boost regulator.

4. The integrated touch screen system of claim 1, wherein the display system controls the power supply to apply the third voltages to the voltage regulator during at least part of the display phase, and the touch sensing system controls the power supply to apply the third voltages to the voltage regulator during at least part of the touch sensing phase.

5. The integrated touch screen system of claim 1, further comprising:

a voltage boost system that boosts the third voltages applied by the power supply during the touch sensing phase, such that a magnitude of the third voltages applied to the voltage regulator during the touch sensing phase is greater than the magnitude of the third voltages applied to the voltage regulator during the display phase.

6. The integrated touch screen system of claim 1, wherein an output voltage level of the power supply is based on a first reference voltage during the display phase, and the output voltage level of the power supply is based on a second reference voltage during the at least one gap period.

7. The integrated touch screen system of claim 1, wherein an output voltage level of the power supply is based on a first reference voltage during the display phase, the output voltage level of the power supply is based on a second reference voltage during the at least one gap period, an output voltage level of the voltage regulator is based on a third reference voltage during the display phase, and the output voltage level of the voltage regulator is based on a fourth reference voltage during the at least one gap period.

8. The integrated touch screen system of claim 1, wherein the power supply applies the third voltages to the voltage regulator during a first portion of the at least one gap period, the touch sensing system including a plurality of drive lines that are stimulated with drive signals during the active sensing periods, and a sense amplifier that receives a sense signal corresponding to the one or more drive signals, the integrated touch screen system further comprising:

a post-noise stabilization system that resets the sense amplifier during a second portion of the at least one gap period, the second portion being after the first portion.

9. The integrated touch screen system of claim 8, wherein the post-noise stabilization system includes a switch connected to a feedback loop of the sense amplifier, and wherein resetting the sense amplifier includes closing the switch to short the feedback loop.

10. A method of managing power in a touch screen system that includes a touch screen including a plurality of display pixels, the plurality of display pixels including an addressing system that includes a plurality of conductive lines, the integrated touch screen system further comprising a driver configured to receive first voltages from a voltage regulator and apply second voltages to the conductive lines based on the received first voltages, the first voltages having a stable level, the method comprising:

updating an image displayed by the display pixels during a display phase, wherein the updating of the image includes actively operating a power supply to apply third voltages to the voltage regulator, and operating the driver to apply second voltages to the conductive lines to address the display pixels; and

sensing touch during a touch sensing phase, the touch sensing phase including a plurality of active sensing periods during which the touch sensing system performs active touch sensing while the power supply is not actively applying the third voltages to the voltage regulator, the touch sensing phase further including at least one gap period between active sensing periods, wherein the power supply is actively operated to apply the third voltages to the voltage regulator, and the driver is operated to apply the second voltages to the conductive lines during the at least one gap period while active touch sensing is not being performed, wherein the power supply applies the third voltages during the one or more gap periods such that the voltage regulator is able to apply the first voltages to the driver during the active sensing periods.

11. The method of claim 10, wherein a display system controls the power supply to apply the third voltages to the voltage regulator during at least part of the display phase, and a touch sensing system controls the power supply to apply the third voltages to the voltage regulator during at least part of the touch sensing phase, the method further comprising:

generating a synchronization signal between the display system and the touch sensing system, wherein the control of the power supply is based on the synchronization signal.

12. The method of claim 10, further comprising:

boosting the third voltages applied by the power supply during the touch sensing phase, such that the magnitude of the third voltages applied to the voltage regulator during the touch sensing phase is greater than the magnitude of the third voltages applied to the voltage regulator during the display phase.

13. The method of claim 10, wherein an output voltage level of the power supply is based on a first reference voltage during the display phase, and the output voltage level of the power supply is based on a second reference voltage during the at least one gap period.

14. The method of claim 10,

wherein an output voltage level of the power supply is based on a first reference voltage during the display phase, the output voltage level of the power supply is based on a second reference voltage during the at least one gap period, an output voltage level of the voltage regulator is based on a third reference voltage during the display phase, and the output voltage level of the voltage regulator is based on a fourth reference voltage during the at least one gap period.

15. The method of claim 10, wherein the touch screen system includes a touch sensing system including a plurality of drive lines that are stimulated with drive signals during the active sensing periods, and a sense amplifier that receives a sense signal corresponding to one or more drive signals, and wherein applying the third voltages during the at least one gap period includes applying the third voltages during a first portion of the at least one gap period, the method further comprising:

resetting the sense amplifier during a second portion of the at least one gap period, the second portion being after the first portion.

16. The method of claim 15, wherein resetting the sense amplifier includes shorting a feedback loop of the sense amplifier.

17. An integrated touch screen system comprising:

a touch screen including a plurality of display pixels, the plurality of display pixels including an addressing system that includes a plurality of conductive lines;

a voltage regulator;

a capacitor coupled to an input of the voltage regulator;

a driver configured to receive first voltages from the voltage regulator and apply second voltages to the conductive lines based on the received first voltages, the first voltages having a stable level;

a display system that updates an image displayed by the display pixels during a display phase, wherein the updating of the image includes actively operating a power supply to apply third voltages to the voltage regulator, and operating the driver to apply the second voltages to the conductive lines to address the display pixels; and

a touch sensing system that senses touch during a touch sensing phase, the touch sensing phase including a plurality of active sensing periods during which the touch sensing system performs active touch sensing while the power supply is not actively applying the third voltages to the voltage regulator, the touch sensing phase further including at least one gap period between active sensing periods, wherein the power supply is actively operated to apply the third voltages to the voltage regulator, and the driver is operated to apply the second voltages to the conductive lines during the at least one gap period while active touch sensing is not being performed, wherein the capacitor is charged while the power supply is actively operated to apply the third voltages, and the charge is transferred from the capacitor to the input of the voltage regulator during the touch phase while the power supply is not actively applying third voltages.

18. The integrated touch screen system of claim 17, wherein each display pixel includes a pixel thin-film transistor (TFT), and the conductive lines include gate lines, each pixel TFT being connected to one gate line.

19. The integrated touch screen system of claim 17, wherein the power supply includes one of a charge pump and an inductive boost regulator.

20. The integrated touch screen system of claim 17, wherein the display system controls the power supply to apply the third voltages to the voltage regulator during at least part of the display phase, and the touch sensing system controls the power supply to apply the third voltages to the voltage regulator during at least part of the touch sensing phase.

21. The integrated touch screen system of claim 17, further comprising:

a voltage boost system that boosts the third voltages applied by the power supply during the touch sensing phase, such that a magnitude of the third voltages applied to the voltage regulator during the touch sensing phase is greater than the magnitude of the third voltages applied to the voltage regulator during the display phase.

22. The integrated touch screen system of claim 17, wherein an output voltage level of the power supply is based on a first reference voltage during the display phase, and the output voltage level of the power supply is based on a second reference voltage during the at least one gap period.

23. The integrated touch screen system of claim 17, wherein an output voltage level of the power supply is based on a first reference voltage during the display phase, the output voltage level of the power supply is based on a second reference voltage during the at least one gap period, an output voltage level of the voltage regulator is based on a third reference voltage during the display phase, and the output voltage level of the voltage regulator is based on a fourth reference voltage during the at least one gap period.

24. The integrated touch screen system of claim 17, wherein the power supply applies the third voltages to the voltage regulator during a first portion of the at least one gap period, the touch sensing system including a plurality of drive lines that are stimulated with drive signals during the active sensing periods, and a sense amplifier that receives a sense signal corresponding to the one or more drive signals, the integrated touch screen system further comprising:

a post-noise stabilization system that resets the sense amplifier during a second portion of the at least one gap period, the second portion being after the first portion.

25. The integrated touch screen system of claim 24, wherein the post-noise stabilization system includes a switch connected to a feedback loop of the sense amplifier, and wherein resetting the sense amplifier includes closing the switch to short the feedback loop.

26. A method of managing power in a touch screen system that includes a touch screen including a plurality of display pixels, the plurality of display pixels including an addressing system that includes a plurality of conductive lines, the integrated touch screen system further comprising a driver configured to receive first voltages from a voltage regulator and apply second voltages to the conductive lines based on the received first voltages, the first voltages having a stable level, the method comprising:

updating an image displayed by the display pixels during a display phase, wherein the updating of the image includes actively operating a power supply to apply third voltages to the voltage regulator, and operating the driver to apply second voltages to the conductive lines to address the display pixels; and

sensing touch during a touch sensing phase, the touch sensing phase including a plurality of active sensing periods during which the touch sensing system performs active touch sensing while the power supply is not actively applying the third voltages to the voltage regulator, the touch sensing phase further including at least one gap period between active sensing periods, wherein the power supply is actively operated to apply the third voltages to the voltage regulator, and the driver is operated to apply the second voltages to the conductive lines during the at least one gap period while active touch sensing is not being performed, wherein a capacitor coupled to the input of the voltage regulator is charged while the power supply is actively operated to apply the third voltages, and the charge is transferred from the capacitor to the input of the voltage regulator during the touch phase while the power supply is not actively applying third voltages.

27. The method of claim 26, wherein a display system controls the power supply to apply the third voltages to the voltage regulator during at least part of the display phase, and a touch sensing system controls the power supply to apply the third voltages to the voltage regulator during at least part of the touch sensing phase, the method further comprising:

generating a synchronization signal between the display system and the touch sensing system, wherein the control of the power supply is based on the synchronization signal.

28. The method of claim 26, further comprising:

boosting the third voltages applied by the power supply during the touch sensing phase, such that the magnitude of the third voltages applied to the voltage regulator during the touch sensing phase is greater than the magnitude of the third voltages applied to the voltage regulator during the display phase.

29. The method of claim 26, wherein an output voltage level of the power supply is based on a first reference voltage during the display phase, and the output voltage level of the power supply is based on a second reference voltage during the at least one gap period.

30. The method of claim 26, wherein an output voltage level of the power supply is based on a first reference voltage during the display phase, the output voltage level of the power supply is based on a second reference voltage during the at least one gap period, an output voltage level of the voltage regulator is based on a third reference voltage during the display phase, and the output voltage level of the voltage regulator is based on a fourth reference voltage during the at least one gap period.

31. The method of claim 26, wherein the touch screen system includes a touch sensing system including a plurality of drive lines that are stimulated with drive signals during the active sensing periods, and a sense amplifier that receives a sense signal corresponding to one or more drive signals, and wherein applying the third voltages during the at least one gap period includes applying the third voltages during a first portion of the at least one gap period, the method further comprising:

resetting the sense amplifier during a second portion of the at least one gap period, the second portion being after the first portion.

32. The method of claim 31, wherein resetting the sense amplifier includes shorting a feedback loop of the sense amplifier.