DYNAMIC POWER ADJUSTMENT OF LEVEL SHIFT FOR NOISE REJECTION IN CAPACITANCE TOUCH SYSTEM

• US 20140218331A1
• Filed: 02/07/2013
• Published: 08/07/2014
• Est. Priority Date: 02/07/2013
• Status: Abandoned Application

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Lee, Hsin-Te, Yang, Chih-Hsiang, Chang, Jen-Chun, Wu, Yung-Chih
• Application Number:
  US13/761,517
• Publication Number:
  US 20140218331A1
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• 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

A dynamic power adjustment circuit for noise rejection in a capacitance touch system includes: a power source configured to generate a fixed power voltage V, a voltage adjustment circuit electrically connected to the power source, and a noise detection circuit electrically connected to the voltage adjustment circuit. The voltage adjustment circuit is configured to generate a plurality of different voltage signals VH(1), VH(2), . . . , VH(n) from the power voltage V, to select one of the voltage signals VH(1), VH(2), . . . , VH(n) as an adjusting voltage VH according to a noise selection signal VH_SEL, and to output the adjusting voltage VH to a level shift for adjusting a driving voltage. The noise detection circuit is configured to generate the noise selection signal VH_SEL for the voltage adjustment circuit according to a plurality of sensing signals RX generated by a capacitance touch sensing device of the capacitance touch system.

Claims

1. A dynamic power adjustment circuit for noise rejection in a capacitance touch system, comprising:

a power source configured to generate a fixed power voltage V;

a voltage adjustment circuit electrically connected to the power source, configured to generate a plurality of different voltage signals VH(1), VH(2), . . . , VH(n) from the power voltage V, to select one of the voltage signals VH(1), VH(2), . . . , VH(n) as a variable adjusting voltage VH according to a noise selection signal VH_SEL, and to output the adjusting voltage VH to a level shift for adjusting a driving voltage, wherein n is an integer larger than 1; and

a noise detection circuit electrically connected to the voltage adjustment circuit, configured to generate the noise selection signal VH_SEL for the voltage adjustment circuit according to a plurality of sensing signals RX generated by a capacitance touch sensing device of the capacitance touch system.

2. The dynamic power adjustment circuit of claim 1, wherein the voltage adjustment circuit comprises:

a plurality of resistor dividers parallely connected to the power source, each resistor divider comprising a first resistance R1 and a second resistance R2 connected in series, wherein the first resistance R1 is connected to the power circuit and the second resistance R2 is grounded, defining a node between the first and second resistances, such that each resistor divider divides the power voltage V to generate one of the voltage signals VH(1), VH(2), . . . , VH(n) at the node; and

a voltage selector electrically connected to the nodes of the resistor dividers and the noise detection circuit such that the voltage selector receives the voltage signals VH(1), VH(2), . . . , VH(n) and determines one of the voltage signals VH(1), VH(2), . . . , VH(n) as the adjusting voltage VH according to the noise selection signal VH_SEL.

3. The dynamic power adjustment circuit of claim 2, wherein for each resistor divider, the voltage signal

4. The dynamic power adjustment circuit of claim 1, wherein the voltage adjustment circuit comprises a power integrated circuit (IC).

5. The dynamic power adjustment circuit of claim 1, wherein the noise detection circuit comprises:

a sensing selector configured to receive the sensing signals RX and select one sensing signal RX for output;

an analog-to-digital converter (ADC) configured to convert the output sensing signal RX to a digital value;

a comparing circuit comparing the digital value of the sensing signal RX to a threshold value, and storing the digital value as a noise data in a noise array when the digital value is greater than or equals to the threshold value;

an average circuit averaging the noise data in the noise array to generate a noise average data when a number of the noise data in the noise array is greater than or equals to a predetermined noise maximum number Noise_MAX; and

a noise selection circuit configured to generate the noise selection signal VH_SEL by looking up a noise average data of the noise array in a voltage adjustment table.

6. A driving system for a touch display having a capacitance touch sensing device for sensing a touch event, comprising:

a touch sensing controller configured to output a plurality of driving voltages and to receive a plurality of sensing signals RX from the capacitance touch sensing device, and to determine whether the touch event occurs by comparing each sensing signal RX to a threshold value;

a level shift configured to receive the driving voltages and a variable adjusting voltage VH and to send a plurality of scanning signals TX to the touch sensing device, wherein the level shift generates the scanning signals by shifting voltage levels of the driving voltages with the adjusting voltage VH; and

a dynamic power adjustment circuit configured to receive the plurality of sensing signals RX from the touch sensing controller, and to generate the adjusting voltage VH according to noise detection of the plurality of sensing signals RX.

7. The driving system of claim 6, wherein the touch display further comprises a display device for displaying an image characterized with a series of frames.

8. The driving system of claim 7, further comprising:

a display driving controller synchronized with the capacitance touch sensing controller.

9. The driving system of claim 7, wherein the display device and the touch sensing device are integrated into a single in-cell touch display panel or stacked up in separate panels.

10. The driving system of claim 6, wherein the dynamic power adjustment circuit comprises:

a power source configured to generate a fixed power voltage V;

a voltage adjustment circuit electrically connected to the power source, configured to generate a plurality of different voltage signals VH(1), VH(2), . . . , VH(n) from the power voltage V, to select one of the voltage signals VH(1), VH(2), . . . , VH(n) as the adjusting voltage VH according to a noise selection signal VH_SEL, and to output the adjusting voltage VH to the level shift for adjusting the driving voltages, wherein n is an integer larger than 1; and

a noise detection circuit electrically connected to the voltage adjustment circuit and the touch sensing controller, configured to receive the plurality of sensing signals RX from the touch sensing controller, and to generate the noise selection signal VH_SEL for the voltage adjustment circuit according to the plurality of sensing signals RX.

11. The driving system of claim 10, wherein the voltage adjustment circuit comprises:

a plurality of resistor dividers parallely connected to the power source, each resistor divider comprising a first resistance R1 and a second resistance R2 connected in series, wherein the first resistance R1 is connected to the power circuit and the second resistance R2 is grounded, defining a node between the first and second resistances, such that each resistor divider divides the power voltage V to generate one of the voltage signals VH(1), VH(2), . . . , VH(n) at the node; and

a voltage selector electrically connected to the nodes of the resistor dividers and the noise detection circuit such that the voltage selector receives the voltage signals VH(1), VH(2), . . . , VH(n) and determines one of the voltage signals VH(1), VH(2), . . . , VH(n) as the adjusting voltage VH according to the noise selection signal VH_SEL.

12. The driving system of claim 11, wherein for each resistor divider, the voltage signal

13. The driving system of claim 10, wherein the voltage adjustment circuit comprises a power integrated circuit (IC).

14. The driving system of claim 10, wherein the noise detection circuit comprises:

a sensing selector configured to receive the sensing signals RX and select one sensing signal RX for output;

an analog-to-digital converter (ADC) configured to convert the output sensing signal RX to a digital value;

a comparing circuit comparing the digital value of the sensing signal RX to a threshold value, and storing the digital value as a noise data in a noise array when the digital value is greater than or equals to the threshold value;

an average circuit averaging the noise data in the noise array to generate a noise average data when a number of the noise data in the noise array is greater than or equals to a predetermined noise maximum number Noise_MAX; and

a noise selection circuit configured to generate the noise selection signal VH_SEL by looking up a noise average data of the noise array in a voltage adjustment table.

15. A method for driving a touch display for sensing a touch event, comprising:

receiving a plurality of sensing signals RX from a capacitance touch sensing device of the touch display;

generating a variable adjusting voltage VH according to noise detection of the plurality of sensing signals RX;

generating a plurality of scanning signals TX according to a plurality of driving voltages and the adjusting voltage VH; and

driving the capacitance touch sensing device by the plurality of scanning signals TX.

16. The method of claim 15, wherein the step of generating the plurality of scanning signals TX comprises:

generating, by a touch sensing controller, the plurality of driving voltages; and

adjusting, by a level shift, the plurality of driving voltages by the adjusting voltage VH to generate the plurality of scanning signals TX.

17. The method of claim 15, wherein the step of generating the adjusting voltage comprises:

generating a plurality of voltage signals VH(1), VH(2), . . . , VH(n) from a fixed power voltage V;

generating a noise selection signal VH_SEL according to the plurality of sensing signals RX; and

selecting one of the voltage signals VH(1), VH(2), . . . , VH(n) as the adjusting voltage VH according to the noise selection signal VH_SEL.

18. The method of claim 17, wherein each of the plurality of voltage signals VH(1), VH(2), . . . , VH(n) is generated by providing the power voltage V with a plurality of resistor dividers in parallel to one another, wherein each resistor divider comprises a first resistance R1 and a second resistance R2 connected in series, wherein the first resistance R1 is provided with the power voltage V and the second resistance R2 is grounded, defining a node between the first and second resistances, such that each resistor divider divides the power voltage V to generate one of the voltage signals VH(1), VH(2), . . . , VH(n) at the node.

19. The method of claim 18, wherein for each resistor divider, the voltage signal

20. The method of claim 17, wherein the step of generating the noise selection signal VH_SEL comprises:

converting each sensing voltage RX to a digital value;

comparing the digital value of each sensing voltage RX to a threshold value, and storing the digital value as a noise data in a noise array when the digital value is greater than or equals to the threshold value;

averaging the noise data in the noise array to generate a noise average data when a number of the noise data in the noise array is greater than or equals to a predetermined noise maximum number Noise_MAXNUM; and

generating the noise selection signal VH_SEL by looking up the noise average data of the noise array in a voltage adjustment table.