Mutual-Capacitance OLED Touch Display Stray Capacitance Reduction

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Solution Overview

Problem

The integration of touch electrodes in liquid crystal or OLED panels leads to significant background stray capacitance, making it difficult to accurately sense mutual-capacitance changes and resulting in noise interference, which discourages the use of mutual-capacitance touch schemes in embedded touch display panels.

Innovation Solution

A mutual-capacitance organic light emitting touch display apparatus is designed with a non-inverting amplifier to output touch sensing signals to the common electrode or a reference point, and a configuration that keeps no common current loop between the display and touch controllers during sensing, reducing background stray capacitance and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If touch electrodes are embedded in panel structure, then device integration is improved, but background stray capacitance increases

Engineering Contradiction:

Improvedevice integrationVSAvoidbackground stray capacitance

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The touch electrode is divided into multiple segments (first touch electrode and second touch electrode) arranged in a matrix pattern. This segmentation reduces the capacitance coupling between any single pair of electrodes, thereby reducing background stray capacitance while maintaining the embedded structure's integration benefits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs asymmetric electrode arrangement where the first touch electrodes and second touch electrodes are positioned at different orientations and locations within the pixel structure. This asymmetric configuration optimizes the capacitance distribution to minimize background stray capacitance while preserving touch sensitivity.

Inventive Principle:

Principle #4Asymmetry

2Adaptability or versatility

If mutual capacitance touch scheme is used, then multi-points detection capability is improved, but sensing accuracy deteriorates under large background stray capacitance

Engineering Contradiction:

Improvemulti-points detection capabilityVSAvoidsensing accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

By segmenting the touch electrodes into multiple independent first and second touch electrodes arranged in matrix, the system can independently sense capacitance changes at multiple locations simultaneously, enabling multi-point detection while each segment's smaller capacitance improves sensing accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements different electrode configurations and driving schemes for different regions of the touch panel, optimizing local sensing characteristics to maintain high accuracy across the entire display area even with embedded electrodes.

Inventive Principle:

Principle #3Local quality

3Device complexity

If touch controller and display controller share common current loop, then circuit complexity is reduced, but noise interference increases

Engineering Contradiction:

Improvecircuit complexityVSAvoidnoise interference

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent separates the display controller and touch controller into independent circuits with separate current loops, preventing noise from the display controller from interfering with the sensitive touch sensing operations, while maintaining overall system integration.

Inventive Principle:

Principle #1Segmentation

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

This approach enhances the accuracy of touch sensing by minimizing the influence of background stray capacitance, allowing for precise detection of capacitance variations and improving the overall performance of mutual-capacitance touch sensing in embedded architectures.

Implementation Method 1

outputting the touch sensing signal to the common electrode layer or a reference point of the display controller by a non-inverting amplifier

Methodology Applied

Scientific EffectNon-inverting amplifier:

Implementation Method 2

an organic light emitting material layer arranged between the common electrode layer and the thin film transistor substrate

Methodology Applied

Scientific EffectOrganic light emitting: Electroluminescence

Data Source

PatentUS10268297B2Mutual-capacitance organic light emitting touch display apparatus

Publication Date: 2019.04.23 SUPERC TOUCH CORP

AI summary

A mutual-capacitance organic light emitting touch display apparatus includes a thin film transistor substrate, a common electrode layer, an organic light emitting material layer, and at least a touch electrode layer, including a plurality of first touch electrodes arranged along a first direction, and a plurality of second touch electrodes arranged along a second direction; a thin film encapsulation layer; a display controller having a display power source, and electrically connected to a thin film transistor, a pixel electrode and the common electrode layer of the thin film transistor substrate; and a touch controller including a touch power source. The touch controller applies a touch driving signal to a selected first touch electrode, and senses a touch sensing signal at a second touch electrode, and outputs the touch sensing signal to the common electrode layer or a reference point of the display controller by a non-inverting amplifier.