Touch Sensing Electrode Width Variation for Uniform Display Sensitivity
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Solution Overview
Problem
Display devices with thin-film encapsulation structures experience uneven touch sensitivity due to non-flat top surfaces, leading to varying touch sensitivity across different locations.
Innovation Solution
A display device design featuring a substrate divided into a display area and a peripheral area, with a light-emitting element layer, a circuit element layer, and an encapsulation film, along with a touch unit comprising intersecting first and second sensing electrodes with varying mesh line widths and patterns to minimize sensitivity unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin-film encapsulation structure is used to seal the light-emitting element, then protection against moisture and oxygen is improved, but touch sensitivity uniformity deteriorates due to non-flat top surface
Solution Approach 1:
The patent applies local quality by varying the line widths of mesh lines in the sensing electrodes based on their position within the display area. Sensing electrodes closer to the center have smaller line widths, while those closer to the periphery have larger line widths. This local adaptation compensates for the non-flat top surface caused by the encapsulation structure, ensuring uniform touch sensitivity across different regions while maintaining the protective encapsulation.
2Ease of manufacture
If sensing electrodes with uniform mesh line widths are used, then manufacturing simplicity is improved, but touch sensitivity uniformity deteriorates across different display areas
Solution Approach 1:
The patent implements local quality by designing mesh lines with position-dependent line widths. The line width of each mesh line is determined based on its distance from the center of the display area, with closer regions having narrower lines and peripheral regions having wider lines. This creates a non-uniform electrode structure that compensates for the encapsulation-induced surface non-flatness, achieving uniform touch sensitivity while remaining manufacturable through standard photolithography processes with appropriate mask design.
3Manufacturing precision
If mesh line widths are increased near the periphery, then touch sensitivity uniformity is improved, but noise influence from underlying elements increases
Solution Approach 1:
The patent applies local quality by strategically varying mesh line widths according to position. In peripheral regions where the encapsulation structure causes greater non-flatness and potential noise, wider mesh lines are used to enhance signal strength and compensate for both the surface variation and noise interference. In central regions, narrower lines suffice as the surface is relatively flatter and noise is minimal. This position-dependent design achieves uniform sensitivity while minimizing overall noise impact.
Solution Approach 2:
The patent employs parameter changes by systematically varying the line width parameter of mesh lines based on their spatial position. The line width is not a fixed parameter but is adjusted according to the distance from the display area center, creating a gradient structure. This parameter variation compensates for the encapsulation structure's effects, ensuring that touch sensitivity remains uniform across the display while adapting to local conditions including noise levels.
Data Source
AI summary
A display device includes a substrate divided into a display area and a peripheral area, a light-emitting element layer on the substrate and including a light-emitting element, a circuit element layer on the substrate and including a circuit element which drives the light-emitting element, an encapsulation film of which portions thereof are respectively in the display area and the peripheral area, and a plurality of sensing electrodes each on the portion of the encapsulation film which is in the display area, including a plurality of first sensing electrodes and a plurality of second sensing electrodes which intersect the first sensing electrodes. Each of the first sensing electrodes includes a plurality of mesh lines intersecting one another in a mesh shape, and widths of the first sensing electrodes increase as a distance of the first sensing electrode from a center of the display area to the peripheral area decreases.