Touch Signal Voltage Balancing for Flicker-Safe Display Panels

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Solution Overview

Problem

Touch driving signals in touch display devices generate noise interference with the reference voltage, affecting the display effect by causing fluctuations in the driving current of the light emitting elements, leading to unstable light emission and visible streaks on the display.

Innovation Solution

Adjust the sum of the voltage values of the first and second touch driving signals to a set value in the mutual-capacitance sensing stage and adjust them to a same third signal, typically a sine wave, in the self-capacitance sensing stage, reducing interference with the data signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If touch driving signals are applied to the touch panel, then touch sensing function is enabled, but noise interference is generated on the reference voltage affecting display quality

Engineering Contradiction:
Improvetouch sensing functionVSAvoidnoise interference on reference voltage
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful inductive coupling effect into a beneficial filtering mechanism. By designing the first and second filtering circuits to respectively filter odd and even harmonics of the touch driving signals, the previously harmful inductive coupling noise is transformed into a controllable filtering process that eliminates interference while preserving the touch sensing function

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the frequency domain parameters of the noise by introducing filtering circuits with specific cutoff frequencies. The first filtering circuit filters odd harmonics while the second filtering circuit filters even harmonics, transforming the broadband noise into a controlled frequency-selective process that eliminates interference without affecting the touch sensing operation

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If touch driving signals interfere with the reference voltage, then touch operation is possible, but the light emitting effect becomes unstable causing visual streaks

Engineering Contradiction:
Improvetouch operationVSAvoidlight emitting stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent converts the harmful inductive coupling effect into a beneficial filtering mechanism. By designing the first and second filtering circuits to respectively filter odd and even harmonics of the touch driving signals, the previously harmful inductive coupling noise is transformed into a controllable filtering process that eliminates interference while preserving the touch sensing function

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces filtering circuits as intermediary elements between the touch driving signals and the reference voltage. These filtering circuits act as mediators that selectively remove harmful frequency components (odd and even harmonics) while allowing the touch sensing function to operate normally, thus protecting the light emitting stability without compromising touch operation

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method effectively prevents noise interference from touch driving signals, stabilizing the light emission and reducing visual streaks on the display by maintaining a constant voltage sum and adjusting the signals in a step-by-step manner.

Implementation Method 1

The touch driving signals STD1 and STD2 may interfere with the reference voltage ELVSS received by the reference electrode RE through inductive coupling of a parasitic capacitance Cp between the touch panel 12 and the reference electrode RE

Methodology Applied
Scientific EffectInductive coupling: Electromagnetic Induction

Implementation Method 2

through inductive coupling of a parasitic capacitance Cp between the touch panel 12 and the reference electrode RE

Methodology Applied
Scientific EffectParasitic capacitance: Capacitance

Implementation Method 3

The noise generated by the reference voltage ELVSS due to the touch driving signals STD1 and STD2 may interfere with the data signal SD received by the transistor MG through inductive coupling of the parasitic capacitance Cd between the reference electrode RE and the display area DA

Methodology Applied
Scientific EffectInductive coupling: Electromagnetic Induction

Data Source

PatentUS12504849B2Touch driving method with set sum of touch driving signals to reduce flicker on display device
Publication Date: 2025.12.23 ILI TECHNOLOGY CORPORATION
  • US12504849B2 patent drawing
  • US12504849B2 patent drawing
  • US12504849B2 patent drawing

AI summary

Provided is a touch driving method for a touch display device. The touch display device includes a display panel and a touch panel. The touch panel is disposed on the display panel. The touch panel includes a first driving electrode and a second driving electrode. The touch driving method includes: a first touch driving signal is provided to the first driving electrode, and a second touch driving signal is provided to the second driving electrode; a sum of a voltage value of the first touch driving signal and a voltage value of the second touch driving signal is adjusted to continue to be equal to a set voltage value in a mutual-capacitance sensing stage of a mutual-capacitance sensing mode; and the first touch driving signal and the second touch driving signal are adjusted to be a third touch driving signal in a self-capacitance sensing stage of a self-capacitance sensing mode.