Touch Sensing High-low Driving Scheme for In-cell Touch LCD Display

• US 20170269779A1
• Filed: 06/07/2016
• Published: 09/21/2017
• Est. Priority Date: 03/15/2016
• Status: Active Grant

• Current Assignee: Solomon Systech Limited
• Original Assignee: Solomon Systech Limited
• Inventors: Chan, Wing Chi Stephen, Chen, Jun, Ng, Sing
• Granted Patent: US 10,452,196 B2
• Time in Patent Office: Days
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

A capacitive sensing method comprising: driving a first excitation signal onto a sensor electrode, and driving a second excitation signal onto the embedded electrodes. Either the first or the second excitation signal has voltage oscillations of constant first amplitude, while the other has voltage oscillations of varying second amplitude. The second amplitude varies between a high amplitude value that is larger than the first amplitude by an amplitude difference and a low amplitude value that is smaller than the first amplitude by the same amplitude difference. The method further comprises using one or more integrators to integrate an electric current due to combined voltage oscillations of the first and the second excitation signals within an integration cycle, and generate an integrated signal for detecting a capacitive change on the sensor electrode; wherein the integration cycle comprises a plurality of voltage oscillations of the first and the second excitation signals.

Claims

1. A capacitive sensing apparatus comprising:

one or more sensor electrodes;

one or more embedded electrodes;

a generator configured to;

generate a first excitation signal and a second excitation signal;

drive the first excitation signal onto at least one of the sensor electrodes;

drive the second excitation signal onto the embedded electrodes;

wherein the first excitation signal and the second excitation signal are periodic waveform signals having alternating peaks and troughs of substantially same frequencies and phases;

wherein one of the first excitation signal and the second excitation signal has voltage oscillations of a constant first amplitude while the other has voltage oscillations of a varying second amplitude;

wherein each voltage oscillation is a positive going pulse or a negative going pulse; and

wherein the second amplitude varies between a high amplitude value that is larger than the first amplitude by an amplitude difference and a low amplitude value that is smaller than the first amplitude by the amplitude difference; and

one or more integrators configured to;

integrate an electric current due to combined voltage oscillations of the first excitation signal and the second excitation signal within a first integration cycle; and

generate one or more first integrated signals for detecting a capacitive change on the sensor electrodes;

wherein the first integration cycle comprises a plurality of voltage oscillations of the first excitation signal and the second excitation signal.

2. The apparatus of claim 1, wherein the second excitation signal has voltage oscillations of the varying second amplitude;

wherein the voltage oscillations of the second excitation signal have alternating high amplitude value and low amplitude value; and

wherein the voltage oscillations of the second excitation signal comprise equal number of the voltage oscillations of high amplitude value and the voltage oscillations of low amplitude value with the first integration cycle.

3. The apparatus of claim 1, wherein the first excitation signal has voltage oscillations of the varying second amplitude;

wherein the voltage oscillations of the first excitation signal have alternating high amplitude value and low amplitude value; and

wherein the voltage oscillations of the first excitation signal comprise equal number of the voltage oscillations of high amplitude value and the voltage oscillations of low amplitude value with the first integration cycle.

4. The apparatus of claim 1, wherein the second excitation signal has voltage oscillations of the varying second amplitude;

wherein the voltage oscillations of the second excitation signal have repeated series of the high amplitude value, followed by the high amplitude value, followed by the low amplitude value, and lastly followed by the low amplitude value;

wherein the first integration cycle comprises the voltage oscillations within time periods when the second excitation signal is having the voltage oscillations of high amplitude value;

wherein a second integration cycle comprises the voltage oscillations within time periods when the second excitation signal is having the voltage oscillations of low amplitude value;

wherein the integrators are further configured to;

integrate an electric current due to combined voltage oscillations of the first excitation signal and the second excitation signal within the second integration cycle; and

generate one or more second integrated signals; and

wherein when combining the first integrated signals and the second integrated signals, the amplitude differences within the first integration cycle and the second integration cycle cancel each other after the integration.

5. The apparatus of claim 1, wherein the first excitation signal has voltage oscillations of the varying second amplitude;

wherein the voltage oscillations of the first excitation signal have repeated series of the high amplitude value, followed by the high amplitude value, followed by the low amplitude value, and lastly followed by the low amplitude value;

wherein the first integration cycle comprises the voltage oscillations within periods of time when the first excitation signal is having the voltage oscillations of high amplitude value;

wherein a second integration cycle comprises the voltage oscillations within periods of time when the first excitation signal is having the voltage oscillations of low amplitude value;

wherein the integrators are further configured to;

integrate an electric current due to combined voltage oscillations of the first excitation signal and the second excitation signal within the second integration cycle; and

generate one or more second integrated signals; and

wherein when combining the first integrated signals and the second integrated signals, the amplitude differences within the first integration cycle and the second integration cycle cancel each other after the integration.

6. A capacitive sensing method comprising:

generating a first excitation signal and a second excitation signal;

driving the first excitation signal onto one or more sensor electrodes;

driving the second excitation signal onto one or more embedded electrodes;

wherein the first excitation signal and the second excitation signal are periodic waveform signals having alternating peaks and troughs of substantially same frequencies and phases;

wherein one of the first excitation signal and the second excitation signal has voltage oscillations of a constant first amplitude while the other has voltage oscillations of a varying second amplitude;

wherein each voltage oscillation is a positive going pulse or a negative going pulse; and

wherein the second amplitude varies between a high amplitude value that is larger than the first amplitude by an amplitude difference and a low amplitude value that is smaller than the first amplitude by the amplitude difference;

integrating an electric current due to combined voltage oscillations of the first excitation signal and the second excitation signal within a first integration cycle; and

generating one or more first integrated signals for detecting a capacitive change on the sensor electrodes;

wherein the first integration cycle comprises a plurality of voltage oscillations of the first excitation signal and the second excitation signal.

7. The method of claim 6, wherein the second excitation signal has voltage oscillations of the varying second amplitude;

wherein the voltage oscillations of the second excitation signal have alternating high amplitude value and low amplitude value; and

wherein the voltage oscillations of the second excitation signal comprise equal number of the voltage oscillations of high amplitude value and the voltage oscillations of low amplitude value with the first integration cycle.

8. The method of claim 6, wherein the first excitation signal has voltage oscillations of the varying second amplitude;

wherein the voltage oscillations of the first excitation signal have alternating high amplitude value and low amplitude value; and

wherein the voltage oscillations of the first excitation signal comprise equal number of the voltage oscillations of high amplitude value and the voltage oscillations of low amplitude value with the first integration cycle.

9. The method of claim 6, wherein the second excitation signal has voltage oscillations of the varying second amplitude;

wherein the voltage oscillations of the second excitation signal have repeated series of the high amplitude value, followed by the high amplitude value, followed by the low amplitude value, and lastly followed by the low amplitude value;

wherein the first integration cycle comprises the voltage oscillations within periods of time when the second excitation signal is having the voltage oscillations of high amplitude value;

wherein a second integration cycle comprises the voltage oscillations within periods of time when the second excitation signal is having the voltage oscillations of low amplitude value;

wherein the capacitive sensing method further comprises;

integrating an electric current due to combined voltage oscillations of the first excitation signal and the second excitation signal within the second integration cycle; and

generating one or more second integrated signals; and

wherein when combining the first integrated signals and the second integrated signals, the amplitude differences within the first integration cycle and the second integration cycle cancel each other after the integration.

10. The method of claim 6, wherein the first excitation signal has voltage oscillations of the varying second amplitude;

wherein the voltage oscillations of the first excitation signal have repeated series of the high amplitude value, followed by the high amplitude value, followed by the low amplitude value, and lastly followed by the low amplitude value;

wherein the first integration cycle comprises the voltage oscillations within periods of time when the first excitation signal is having the voltage oscillations of high amplitude value;

wherein a second integration cycle comprises the voltage oscillations within periods of time when the first excitation signal is having the voltage oscillations of low amplitude value;

wherein the capacitive sensing method further comprises;

integrating an electric current due to combined voltage oscillations of the first excitation signal and the second excitation signal within the second integration cycle; and

generating one or more second integrated signals; and

wherein when combining the first integrated signals and the second integrated signals, the amplitude differences within the first integration cycle and the second integration cycle cancel each other after the integration.