Shielding Layer for Display Device Touch Noise Reduction
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Solution Overview
Problem
Display devices with integrated touch screens face issues such as touch noise interference, degradation in touch performance, and outgassing defects due to the overlap of driving signals with touch signals, which affect the accuracy and stability of touch sensing.
Innovation Solution
A shielding layer is introduced between the connection pattern and emission driver/emission clock lines in the non-active area, electrically connected to a low potential power line, to minimize signal noise and prevent driving signal interference with touch signals, while also allowing for outgassing through a mesh structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cathode electrode is disposed to overlap all touch routing lines, then touch signal interference is reduced, but the design margin of the cathode electrode is compromised
Solution Approach 1:
A shielding layer is introduced as an intermediary component between the emission driver/emission clock lines and the touch routing lines. This shielding layer, electrically connected to the low potential power line, acts as a mediator that blocks driving signal noise from reaching the touch signals, thereby reducing interference without requiring the cathode electrode to extend further than its design margin allows.
2Measurement precision
If a shielding layer is disposed to block driving signal noise, then touch precision is improved, but outgassing defects may occur in the planarization layer
Solution Approach 1:
The shielding layer is designed with a mesh structure that provides porosity. This porous configuration allows the shielding layer to block driving signal noise effectively while simultaneously enabling outgassing from the planarization layer underneath. The mesh structure acts as a permeable barrier that permits gas molecules to pass through, preventing outgassing defects while maintaining noise shielding functionality.
3Reliability
If the cathode electrode is extended to cover more area, then touch noise is reduced, but the device complexity increases
Solution Approach 1:
Instead of extending the cathode electrode to reduce touch noise, a shielding layer is introduced as a separate intermediary component. This shielding layer, connected to the low potential power line, provides the necessary noise blocking functionality without requiring changes to the cathode electrode's geometry or extension, thereby avoiding increased device complexity.
Solution Approach 2:
The noise shielding function is segmented from the cathode electrode by introducing a separate shielding layer. This segmentation allows the cathode electrode to maintain its original design and geometry while the shielding layer independently provides the noise blocking function, avoiding the need to modify or extend the cathode electrode structure.
Data Source
AI summary
A display device includes a substrate including an active area including a plurality of pixels, and a non-active area; a plurality of light emitting elements in the active area on the substrate; an emission driver and a plurality of emission clock lines in the non-active area; a connection pattern on the emission driver and the plurality of emission clock lines in the non-active area and formed of the same material as an anode; an encapsulation layer on the plurality of light emitting elements and the connection pattern; a touch sensing unit on the encapsulation layer in the active area; a low potential power line disposed more outwardly than the plurality of emission clock lines in the non-active area; and a shielding layer between the connection pattern, and the emission driver and the plurality of emission clock lines in the non-active area and electrically connected to the low potential power line.