Touch Sensor Electrode Layering for Flexible Display Capacitance
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Solution Overview
Problem
Flexible display devices with ultrathin passivation layers suffer from retransmission phenomena, leading to inaccurate touch recognition due to the lack of capacitance difference between touch electrodes before and during user interaction.
Innovation Solution
The display device incorporates a substrate with sensing electrodes and driving electrodes in different conductive layers, separated by a first touch insulating layer, which includes an organic material to prevent charge retransmission and enhance touch sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the thickness of the passivation layer is reduced to be ultrathin, then bending stress of the display device is reduced, but retransmission phenomenon occurs causing inaccurate touch recognition
Solution Approach 1:
The patent transitions from a single-layer touch sensor structure to a multi-layer structure with driving electrodes and sensing electrodes positioned at different vertical levels (different dimensions). This spatial separation in the thickness direction prevents charge retransmission while maintaining ultrathin passivation layer benefits for flexibility.
Solution Approach 2:
The patent introduces a touch insulating layer as an intermediary between the driving electrodes and sensing electrodes. This intermediate layer electrically isolates the two electrode types, preventing charge retransmission from the driving electrodes to the sensing electrodes, thereby resolving the measurement precision issue while maintaining the ultrathin design.
2Device complexity
If driving electrodes and sensing electrodes are placed in the same conductive layer, then device structure is simplified, but charge retransmission occurs reducing capacitance difference
Solution Approach 1:
The patent positions driving electrodes and sensing electrodes in different vertical layers (different dimensions) rather than the same planar layer. This three-dimensional separation maintains electrical isolation between the electrode types, preserving the capacitance difference needed for accurate touch detection while managing device complexity through organized layering.
Solution Approach 2:
The patent divides the touch sensor into distinct functional segments: driving electrodes in one conductive layer and sensing electrodes in another conductive layer, separated by insulating layers. This segmentation electrically isolates the two electrode types, preventing charge retransmission and maintaining the capacitance difference necessary for accurate touch recognition.
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 allows for precise recognition of touch inputs by increasing the capacitance difference between driving and sensing electrodes, thereby improving touch sensitivity and reducing bending stress on the display panel.
Implementation Method 1
A first touch insulating layer which insulates the second touch conductive layer from the common electrode and includes an organic material
Implementation Method 2
A touch driving circuit sensing a change amount of mutual capacitance formed between the plurality of driving electrodes and the plurality of sensing electrodes
Data Source
AI summary
A display device includes a substrate. A plurality of sensing electrodes is on the substrate. A first touch insulating layer is disposed above the plurality of sensing electrodes. A plurality of driving electrodes is disposed on an upper surface of the first touch insulating layer. The plurality of driving electrodes receives a touch driving signal. A touch driving circuit sensing a change amount of mutual capacitance is formed between the plurality of driving electrodes and the plurality of sensing electrodes by the plurality of sensing electrodes. The first touch insulating layer includes an organic material.