Bar-and-stripe touch electrodes for signal uniformity
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Solution Overview
Problem
Current touch sensor panels with capacitive touch sensing systems face challenges in achieving uniform touch signal levels and precision in detecting touch locations, particularly as objects move across the surface, due to limitations in electrode configurations and visibility of metal mesh patterns.
Innovation Solution
The implementation of a bar-and-stripe pattern for touch electrodes formed from metal mesh, where 'stripes' are interconnected by bridges in a second layer of metal mesh, and 'bars' may also include bridges, with non-linear boundaries and dummy cuts to reduce visibility and maintain electrical potential, enhancing signal uniformity and detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacitive touch sensor panels use standard electrode configurations, then manufacturing is simpler, but touch signal uniformity and detection precision deteriorate as objects move across the surface
Solution Approach 1:
The touch electrode is divided into multiple segments arranged in a bar-and-stripe pattern, where each segment can independently contribute to the capacitive signal. This segmentation allows for more uniform signal distribution across the electrode surface, improving touch location detection precision while maintaining manageable complexity through systematic arrangement of the segments.
Solution Approach 2:
Different regions of the touch electrode are given different geometric characteristics (bars and stripes) to optimize local signal generation. The bar regions provide strong horizontal signal components while stripe regions provide vertical signal components, creating locally optimized signal characteristics that collectively improve overall detection precision across the entire electrode surface.
2Illumination intensity
If metal mesh touch electrodes are used to improve transparency, then visibility of the mesh pattern increases, affecting display quality
Solution Approach 1:
The harmful visual element (metal mesh pattern) is extracted and replaced with a bar-and-stripe pattern that provides the necessary electrical functionality without the visual defects. The bar-and-stripe configuration achieves the required touch sensitivity while maintaining better optical properties and display quality.
Solution Approach 2:
The visual appearance of the electrode pattern is changed from a fine metal mesh to a coarser bar-and-stripe pattern. This change in pattern geometry reduces the visibility of the electrode structure while maintaining its electrical function, thereby improving display quality and reducing visual interference with the underlying display content.
3Reliability
If simple electrode patterns are used, then manufacturing is easier, but touch signal levels and uniformity are insufficient
Solution Approach 1:
The electrode is segmented into multiple bar and stripe regions that can be independently fabricated using standard photolithography and etching processes. This segmentation approach maintains ease of manufacture by using conventional techniques while achieving superior signal uniformity through the distributed arrangement of the segments across the electrode surface.
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 improves touch signal levels and uniformity, leading to more precise and accurate touch location detection, reduced wobble, and increased modulation between the finger and sensor, enhancing overall touch performance.
Implementation Method 1
In the case of some touch sensing systems, a physical touch on the display is not needed to detect a touch. For example, in some capacitive-type touch sensing systems, fringing electrical fields used to detect touch can extend beyond the surface of the display, and objects approaching near the surface may be detected near the surface without actually touching the surface.
Data Source
AI summary
This relates to touch sensor panels/touch screens including touch electrodes in a bar-and-stripe pattern. The bar-and-stripe pattern can improve touch signal levels for touch detection and improve uniformity of touch signal as objects move across the touch sensor panel/touch screen. Touch electrodes in a bar-and-stripe pattern can be formed from metal mesh in one or more layers of metal mesh. In some examples, “stripes” can be formed from groups of touch electrode segments in a first layer of metal mesh and can be interconnected by bridges formed in a second layer of metal mesh, different from the first layer of metal mesh, in the active area of the touch screen. Multiple stripes can be interconnected in the border area and/or in the active area to form a row touch electrode. In some examples, “bars” may also include bridges in the second layer of metal mesh.