Dummy Routing Wires for Parasitic Capacitance in Touch Displays

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Solution Overview

Problem

The existing touch sensor integrated type display devices suffer from image defects due to electric field differences across pixels, caused by uneven positioning of routing wires, leading to parasitic capacitance that affects liquid crystal molecule driving and results in light leakage and display defects.

Innovation Solution

The introduction of dummy routing wires that traverse the touch/common electrodes without connection, allowing for a common voltage supply during display operations and a touch driving signal with a load-free driving signal during touch operations, eliminating parasitic capacitance and ensuring equal electric field distribution across all pixels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If routing wires are positioned to connect touch/common electrodes, then touch sensing function is enabled, but electric field differences cause parasitic capacitance and display defects

Engineering Contradiction:

Improvetouch sensing functionVSAvoidparasitic capacitance causing display defects

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The routing wire structure is segmented into two distinct types: touch routing wires that connect to touch/common electrodes for touch sensing, and dummy routing wires that traverse without connection to compensate for electric field differences. This segmentation allows each wire type to perform its specific function independently, resolving the contradiction between enabling touch sensing and preventing parasitic capacitance-induced display defects

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Dummy routing wires act as intermediary elements that introduce compensating electric fields to counterbalance the harmful electric field differences created by touch routing wires. These dummy wires serve as mediators that neutralize the parasitic capacitance effects, allowing both touch sensing functionality and display quality to coexist

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If touch routing wires are used for touch operation, then touch recognition is enabled, but electric field non-uniformity causes visible mura defects

Engineering Contradiction:

Improvetouch recognitionVSAvoiddisplay uniformity

Core Design Contradiction:

Ease of operationVSIllumination intensity

Solution Approach 1:

The patent employs asymmetric routing wire configuration where touch routing wires and dummy routing wires are deliberately positioned differently across the display panel. The dummy wires are strategically placed to create compensating electric field patterns that counterbalance the asymmetric electric field disturbances caused by touch routing wires, thereby maintaining display uniformity while preserving touch recognition capability

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

Different regions of the display panel are assigned different wire functions: touch routing wires are positioned where touch sensing is needed, while dummy routing wires are positioned in specific regions to locally compensate for electric field non-uniformities. This local differentiation allows each area to have optimized properties for its specific function, resolving the conflict between touch operation and display uniformity

Inventive Principle:

Principle #3Local quality

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 configuration prevents visible mura defects and ensures accurate touch recognition without compromising display quality by maintaining equal electric field distribution and eliminating parasitic capacitance between touch/common electrodes and dummy routing wires.

Implementation Method 1

parasitic capacitance between gate lines and data lines constituting the display device are very large. Therefore, it is difficult to accurately recognize touch positions because of the parasitic capacitances

Methodology Applied

Scientific EffectParasitic capacitance: Parasitic Capacitance

Implementation Method 2

measures changes in a capacitance of each independent pattern, thereby deciding whether or not a touch operation is performed

Methodology Applied

Scientific EffectElectric field: Electric Field

Data Source

PatentUS10503298B2Touch sensor integrated type display device

Publication Date: 2019.12.10 LG DISPLAY CO LTD

AI summary

Disclosed herein is a touch sensor integrated type display device including gate lines; data lines; and pixel electrodes to which data signals are supplied through the data lines; touch/common electrodes; touch/common routing wirings connected to the touch/common electrodes to supply a common voltage and a touch driving signal; and dummy routing wires not connected to the touch/common electrodes. The common voltage is supplied to the touch/common routing wires and the dummy routing wires during a display operation period, and the touch driving signal is supplied to the touch/common routing wires and a load free driving signal is supplied to the dummy routing wires during a touch operation period.