METHOD AND APPARATUS CONTROLLING TOUCH SENSING SYSTEM AND TOUCH SENSING SYSTEM EMPLOYING SAME

• US 20110273399A1
• Filed: 04/13/2011
• Published: 11/10/2011
• Est. Priority Date: 05/04/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: LEE, Chang-ju
• Granted Patent: US 8,872,789 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components

Abstract

A method of calibrating a touch sensing system includes connecting an impedance load to a touch sensing signal path in a gain adjustment mode, adjusting a gain of an amplifier that amplifies a signal input to the touch sensing signal path in the gain adjustment mode by evaluating an output signal of the amplifier, and disconnecting the impedance load from the touch sensing signal path after adjusting the amplifier gain.

Claims

1. A method of calibrating a touch sensing system including a touch panel, the method comprising:

connecting an impedance load to a touch sensing signal path in a gain adjustment mode;

adjusting an amplifier gain of an amplifier used to amplify a signal input to the touch sensing signal path in the gain adjustment mode by evaluating an output signal of the amplifier; and

disconnecting the impedance load from the touch sensing signal path after the adjustment of the amplifier gain.

2. The method of claim 1, wherein the impedance load comprises a capacitor or a resistor.

3. The method of claim 1, wherein the impedance load comprises a variable impedance load.

4. The method of claim 1, wherein the impedance load is provided in a touch sensing signal processor.

5. The method of claim 1, further comprising:

setting the impedance load to be a defined value in accordance with operating characteristics of a product incorporating the touch panel before connecting of the impedance load to the touch sensing signal path.

6. The method of claim 1, wherein adjusting the amplifier gain comprises adjusting the amplifier gain to allow an amplitude of an output signal of the amplifier to fall within a target range.

7. The method of claim 1, wherein adjusting the amplifier gain comprises sequentially selecting one of a plurality of touch sensing electrodes of the touch panel using a single amplifier receiving the touch sensing signal, and

a digital value for the amplifier gain as respectively adjusted upon selecting the one of the plurality of touch sensing electrode is stored in a memory.

8. The method of claim 1, wherein the gain adjustment mode is performed whenever a product incorporating the touch panel is initialized, or after a predetermined time passes.

9. An apparatus calibrating a touch sensing system including a touch panel, the apparatus comprising:

an impedance load;

a switching unit connecting and disconnecting the impedance load with respect to a touch sensing signal path in response to a first control signal;

an amplifier that amplifies a signal input to the touch sensing signal path using an amplifier gain determined in response to a second control signal; and

a calibration controller that generates the first control signal to connect the impedance load to the touch sensing signal path in a gain adjustment mode, and the second control signal to adjust the amplifier gain by evaluating an output signal of the amplifier.

10. The apparatus of claim 9, wherein the impedance load comprises a capacitor or a resistor.

11. The apparatus of claim 9, wherein the impedance load comprises a variable impedance load.

12. The apparatus of claim 9, wherein the impedance load comprises:

a first terminal being connected and disconnected by the switching unit with respect to the touch sensing signal path; and

a second terminal connected to ground or a fixed DC voltage.

13. The apparatus of claim 9, wherein the amplifier is a differential amplifier comprising:

a first input terminal connected to the touch sensing signal path;

a second input terminal connected to a sensing pulse transfer path; and

at least one of a variable resistor and a variable capacitor connected in parallel between an output terminal and the first input terminal.

14. The apparatus of claim 9, wherein the impedance load comprises a first terminal connected and disconnected by the switching unit with respect to the touch sensing signal path, and a second terminal connected to a sensing pulse transfer path, and

the amplifier comprises a first input terminal connected to the touch sensing signal path, and a second input terminal connected to ground or a fixed DC voltage.

15. The apparatus of claim 9, further comprising:

a multiplexer that selects one of a plurality of electrodes of the touch panel and connects a selected electrode to the touch sensing signal path, wherein the calibration controller controls the multiplexer to sequentially select one of a plurality of touch sensing electrodes of the touch panel and connect a selected touch sensing electrode to the touch sensing signal path to adjust the amplifier gain in accordance with each touch sensing electrode.

16. The apparatus of claim 9, further comprising:

a parasitic capacitance compensation circuit that removes a parasitic capacitance generated from the touch sensing signal path.

17. A touch sensing system comprising:

a touch panel that outputs a touch sensing signal corresponding to a change in impedance of a sensing unit arranged at a plurality of sensing channels; and

a touch sensing signal processor that receives the touch sensing signal from the touch panel and converts the received touch sensing signal to a signal, and outputs the signal,

wherein the touch sensing signal processor comprises a calibration circuit that adjusts an amplifier gain amplifying a signal input to the touch sensing signal path in a state where an impedance load is connected to a touch sensing signal path in a gain adjustment mode, and

the impedance load being disconnected from the touch sensing signal path after the adjustment of the amplifier gain.

18. The touch sensing system of claim 17, wherein the calibration circuit comprises:

an impedance load;

a switching unit connecting and disconnecting the impedance load with respect to a touch sensing signal path in response to a first control signal;

an amplifier that amplifies a signal input to the touch sensing signal path using an amplifier gain determined in response to a second control signal; and

a calibration controller that generates the first control signal to connect the impedance load to the touch sensing signal path in a gain adjustment mode, and the second control signal to adjust the amplifier gain by evaluating an output signal of the amplifier.

19. The touch sensing system of claim 18, wherein the calibration circuit further comprises a multiplexer that selects one of a plurality of electrodes of a touch panel and connects a selected electrode to the touch sensing signal path, wherein the calibration controller controls the multiplexer to sequentially select one of a plurality of touch sensing electrodes of the touch panel and connect a selected touch sensing electrode to the touch sensing signal path to adjust the amplifier gain for each touch sensing electrode.

20. An apparatus calibrating a touch sensing system including a touch panel, the apparatus comprising:

an impedance load connected to a touch sensing signal path while the apparatus operates in a gain adjustment mode, and disconnected from the touch sensing signal path while the apparatus operates in a mode other than the gain adjustment mode, wherein an amplifier gain applied to a signal input to the touch sensing signal path is determined during the gain adjustment mode; and

a parasitic capacitance compensation circuit that removes a parasitic capacitance generated from the touch sensing signal path during the gain adjustment mode.