METHOD FOR DETECTING A TOUCH POINT ON A TOUCH SENSING DEVICE AND DEVICE THEREOF

• US 20120194468A1
• Filed: 10/14/2011
• Published: 08/02/2012
• Est. Priority Date: 02/01/2011
• Status: Abandoned Application

• Current Assignee: Weltrend Semiconductor Inc.
• Original Assignee: Weltrend Semiconductor Inc.
• Inventors: Yeh, Shui-Chin, Wu, Kun-Tai, Wei, Chun-Yi
• Application Number:
  US13/273,244
• Publication Number:
  US 20120194468A1
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• 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 3/044 by capacitive means
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0448 Details of the electrode shape, e.g. for enhancing the detection of touches, for generating specific electric field shapes, for enhancing display quality

Abstract

A touch sensing device includes four driving electrodes, four sensing circuits, a controller and a substrate. Each sensing circuit is coupled to one of the four driving electrodes, for sensing electrical charges of the corresponding sensing electrode. The four driving electrodes, disposed on the substrate, are electrically independent to each other. Each sensing circuit detects the electrical charges of the corresponding driving electrode, and generates a count according to the electrical charges of the corresponding driving electrode. The controller calculates a position of a touch point on the touch sensing device according to counts generated by the four sensing circuits.

Claims

1. A touch sensing device, comprising:

a substrate;

four driving electrodes, disposed on the substrate;

four sensing circuits, wherein each sensing circuit is coupled to a driving electrode of the four driving electrodes, for detecting electrical charges of the driving electrode; and

a controller, for determining a position of where the touch sensing device is touched according to electrical charges detected by the four sensing circuits.

2. The touch sensing device of claim 1, wherein the sensing circuit comprises:

a capacitor, comprising a first end, and a second end coupled to a ground end;

a first switch, comprising a first end coupled to a voltage source, and a second end coupled to the driving electrode;

a second switch, comprising a first end coupled to the driving electrode, and a second end coupled to the first end of the capacitor;

a third switch, comprising a first end coupled to the first end of the capacitor, and a second end coupled to a resistor;

an operational amplifier, comprising a first input end for receiving a reference voltage, a second input end coupled to the first end of the capacitor, and an output end; and

a counter circuit, coupled to the output end of the operational amplifier, for calculating a time required for discharging the capacitor to a voltage level of the reference voltage.

3. The touch sensing device of claim 2, wherein the voltage level of the reference voltage is half a voltage level of the voltage source.

4. The touch sensing device of claim 1, wherein the four driving electrodes are arranged in a two by two matrix.

5. The touch sensing device of claim 1, wherein the four driving electrodes are electrically independent on the substrate.

6. A method for detecting a touch point on a touch sensing device, comprising:

in a first duration, charging four driving electrodes;

in a second duration after the first duration, the four driving electrodes charging four sensing circuits; and

in a third duration after the second duration, determining a position of the touch point according to electrical charges of the four sensing circuits.

7. The method of claim 6, wherein determining the position of the touch point according to the electrical charges of the four sensing circuits is determining the position of the touch point according to a time to charge a capacitor of each of the four sensing circuits.

8. The method of claim 6, wherein determining the position of the touch point according to the electrical charges of the four sensing circuits is determining the position of the touch point according to a time to discharge a capacitor of each of the four sensing circuits.

9. The method of claim 6, wherein charging the four driving electrodes is charging the four driving electrodes simultaneously, and the four driving electrodes charging the four sensing circuits is the four driving electrodes charging the four sensing circuits simultaneously.

10. The method of claim 6, wherein the four driving electrodes charging the four sensing circuits is the four driving electrodes charging a capacitor of each of the four sensing circuits respectively.