Touch Sensor Panel Border Trace Design

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Solution Overview

Problem

The formation of metal traces in the border areas of touch sensor panels requires thin, low resistance materials, leading to high manufacturing costs and reliability issues, as well as inadequate noise shielding from sources like LCDs.

Innovation Solution

The use of higher resistivity materials, such as Molybdenum/Niobium, in wider traces within the border areas of touch sensor panels, which are interleaved with drive and sense lines, reduces manufacturing costs and improves reliability by providing better noise immunity and a larger fixed-potential surface area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thin, low resistance conductive material is used to form metal traces in border areas, then electrical conductivity is improved, but manufacturing costs increase and reliability deteriorates

Engineering Contradiction:
Improvetrace reliabilityVSAvoidmanufacturing costs
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies different conductive material properties to different regions of the touch sensor panel. Specifically, higher resistivity materials are used in the border areas where metal traces are formed, while the central sensing area maintains its original transparent conductive material. This local differentiation allows the use of more cost-effective and reliable materials in the border regions without compromising the overall device performance.

Inventive Principle:
Principle #3Local quality

2Object-affected harmful factors

If thin metal traces are used in border areas, then manufacturing complexity is reduced, but noise shielding capability deteriorates

Engineering Contradiction:
Improvenoise shieldingVSAvoidtrace structure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent compensates for the reduced noise shielding capability of thinner traces by increasing the trace width in the border areas. This dimensional change (making traces wider rather than thicker) provides a larger surface area for noise shielding while maintaining a simpler single-layer structure, thus improving noise protection without increasing manufacturing complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP2806341B1Touch sensor panel
Publication Date: 2022.09.07 APPLE INC
  • EP2806341B1 patent drawingFigure 1A~1B
  • EP2806341B1 patent drawingFigure 1C
  • EP2806341B1 patent drawingFigure 2A~2B

AI summary

The formation of metal traces (102,104) in the border areas (106,108) of a touch sensor panel (110) to provide improved reliability, better noise rejection, and lower manufacturing costs is disclosed. The metal traces (102,104) can be coupled to rows (100) on the touch sensor panel (110) in an interleaved manner, so that any two successive rows can be coupled to metal traces in border areas on opposite sides of the touch sensor panel. In addition, by utilizing the full width available in the border areas in some embodiments, the metal traces can be formed from higher resistivity metal, which can reduce manufacturing costs and improve trace reliability. The wider traces can also provide better noise immunity from noise sources such as an LCD by providing a larger fixed-potential surface area and by more effectively coupling the drive lines to the fixed potential.