Asymmetric Conductive Mesh for Touch Sensors to Reduce Moiré Patterns
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Solution Overview
Problem
Capacitive touch sensors face challenges in minimizing moiré pattern effects when overlaid on displays, leading to brightness and color variations, which affect the optical performance and user experience.
Innovation Solution
A touch sensor design featuring a conductive mesh pattern with specific angles and spacings of conductive lines, optimized to reduce the visibility of moiré patterns by controlling the angles and separations of conductive lines relative to the display's pixel pattern, thereby improving optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive mesh pattern is overlaid on a display to enable touch sensing, then touch detection capability is improved, but moiré pattern effects occur causing brightness and color variations
Solution Approach 1:
The patent applies asymmetry by using non-uniform spacing between conductive lines in the mesh pattern. Instead of equal spacing, the spacing varies to disrupt the periodicity that causes moiré patterns when the mesh overlays display pixels. This asymmetric arrangement breaks the regular interference patterns while maintaining touch sensing functionality.
Solution Approach 2:
The patent implements local quality by varying the spacing of conductive lines in different regions of the mesh pattern. Specific areas have different line densities and spacing configurations to locally optimize for reducing moiré effects in regions where display pixels create problematic interference patterns, while maintaining overall touch detection performance.
2Measurement precision
If conductive lines are spaced closer together to improve touch sensing resolution, then measurement precision is improved, but moiré pattern visibility increases
Solution Approach 1:
The patent uses asymmetric spacing where conductive lines are not uniformly distributed. Some regions have closer spacing for improved resolution, while other regions have wider spacing to reduce moiré visibility. This non-uniform asymmetric arrangement allows the system to achieve good touch sensing resolution without the uniform periodicity that exacerbates moiré patterns.
3Object-affected harmful factors
If conductive lines are spaced further apart to reduce moiré patterns, then brightness variations are reduced, but touch sensing precision deteriorates
Solution Approach 1:
The patent applies local quality by implementing region-specific spacing configurations. In areas where moiré patterns are most problematic, wider spacing reduces brightness variations. In areas where touch sensing precision is critical, closer spacing maintains detection accuracy. This localized optimization allows the system to address both concerns in different regions simultaneously.
Data Source
AI summary
In one embodiment, an apparatus includes a touch sensor that includes a mesh of conductive material configured to extend across a display that includes multiple pixels that each include sub-pixels. The mesh includes multiple first and second lines of conductive material. The first lines are substantially parallel to each other, and the second lines are substantially parallel to each other. Each of the pixels has a first pixel pitch (PPx) along a first axis and a second pixel pitch (PPy) along a second axis that is substantially perpendicular to the first axis. The first pixel pitch is a distance between corresponding features of two adjacent pixels along the first axis, and the second pixel pitch is a distance between corresponding features of two adjacent pixels along the second axis. The first lines extend across the display at a first angle relative to the first axis.