Touch Display Capacitance Coupling Elimination

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Solution Overview

Problem

In touch display devices, parasitic capacitance between touch electrodes and backlight iron frames causes interference with touch signals, leading to high frequency noise due to capacitive coupling and vibration of the backlight film.

Innovation Solution

Electrically connecting the touch electrode and backlight iron frame to a shared touch signal terminal, ensuring they receive the same touch signal, typically a square-wave signal, to eliminate capacitance coupling and synchronize voltage, thereby preventing the formation of virtual capacitors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the touch electrode and backlight iron frame are not electrically connected to a shared touch signal terminal, then the structure is simpler, but parasitic capacitance causes touch signal interference and high frequency noise

Engineering Contradiction:

Improvetouch signal stabilityVSAvoidelectrical connection structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the electrical connection of the touch electrode and backlight iron frame to a shared touch signal terminal. This causes both components to have the same voltage potential, eliminating the voltage difference that creates parasitic capacitance. The merging of their electrical references resolves the technical contradiction by improving touch signal stability without significantly increasing structural complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies equipotentiality by connecting both the touch electrode and backlight iron frame to the same touch signal terminal, ensuring they maintain the same voltage potential. This eliminates the voltage difference between the two components, thereby eliminating parasitic capacitance and its harmful effects on touch signal stability.

Inventive Principle:

Principle #12Equipotentiality

2Reliability

If the touch electrode and backlight iron frame have different voltages, then the electrical connection structure is simpler, but virtual capacitors form causing capacitive coupling and touch effect degradation

Engineering Contradiction:

Improvetouch effect qualityVSAvoidsignal transmission structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #12Equipotentiality

Solution Approach 2:

The patent converts the potentially harmful parasitic capacitance into a beneficial configuration by intentionally connecting both the touch electrode and backlight iron frame to the same signal terminal. This transforms what would normally be a source of interference into a design feature that eliminates voltage differences and prevents virtual capacitor formation.

Inventive Principle:

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

3Object-affected harmful factors

If the backlight film is not electrically connected to the touch signal terminal, then the manufacturing process is simpler, but the backlight film vibrates due to capacitive coupling causing high frequency noise

Engineering Contradiction:

Improvehigh frequency noiseVSAvoidbacklight module assembly

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent merges the electrical connection of the backlight iron frame (supporting the backlight film) to the touch signal terminal, causing the backlight assembly to have the same voltage potential as the touch electrode. This eliminates capacitive coupling and the resulting backlight film vibration, thereby reducing high frequency noise without significantly complicating the manufacturing process.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies equipotentiality by connecting the backlight iron frame to the same touch signal terminal as the touch electrode, ensuring they maintain the same voltage potential. This eliminates the voltage difference that causes capacitive coupling and backlight film vibration, thereby eliminating high frequency noise.

Inventive Principle:

Principle #12Equipotentiality

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 solution enhances touch sensitivity and reduces noise by ensuring the touch electrode and backlight iron frame have the same voltage, eliminating capacitance coupling and the associated noise issues.

Implementation Method 1

parasitic capacitance between the touch electrodes and the backlight iron frames. Virtual capacitor C is formed between the touch electrode 11 and the backlight iron frame 12. Due to the capacitive coupling effect of the virtual capacitor C

Methodology Applied

Scientific EffectCapacitance coupling: Capacitance

Data Source

PatentUS11287928B2Touch display device and touch display

Publication Date: 2022.03.29 WUHAN CHINA STAR OPTOELECTRONICS TECH CO LTD

AI summary

A touch display device and a touch display are provided. The touch display device includes a touch electrode and a backlight module disposed opposite to the touch electrode. The backlight module includes a backlight film and a backlight iron frame supporting the backlight film. The backlight film is disposed between the touch electrode and the backlight iron frame; and the touch electrode and the backlight iron frame are electrically connected to a touch signal terminal. The touch signal terminal is configured to transmit a touch signal to the touch electrode and the backlight iron frame. The touch electrode and the backlight iron frame receive a same touch signal, thereby eliminating the capacitance coupling effect between the touch electrode and the backlight iron frame, increasing touch sensitivity, and reducing vibration noise of the backlight film. The touch display includes the touch display device, and has advantages of the touch display device.