Capacitive Touch Sensor With Narrow Second Layer Intervals
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Solution Overview
Problem
Conventional capacitive touch sensors face issues with external electromagnetic interference (EMI) and radio-frequency interference (RFI) due to widened intervals between sensing strings, which also cause optical interference and image quality issues like blur, distortion, and moiré patterns.
Innovation Solution
A capacitive touch sensor design featuring orthogonally arranged first and second sensing layers with narrower intervals on the second layer for EMI shielding and optical uniformity, allowing adjustment of the effective electrode area without altering the electrode pattern, using conductive materials like metal oxide or graphene and a substrate with high light permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interval between adjacent sensing strings is widened to guarantee insulation, then insulation between sensing strings is improved, but the sensor becomes susceptible to external electromagnetic interference and radio-frequency interference
Solution Approach 1:
The patent introduces a shielding layer as an intermediary component between the sensing strings and the external environment. This shielding layer acts as a mediator that blocks electromagnetic and radio-frequency interference from reaching the sensing strings, while not interfering with the insulation function between adjacent sensing strings.
Solution Approach 2:
The patent employs composite material structures by combining the insulative substrate material with conductive shielding material in a layered configuration. This composite structure integrates both insulation and electromagnetic shielding functions within a unified sensor design, resolving the contradiction between maintaining insulation and preventing interference.
2Reliability
If the interval between adjacent sensing strings is widened to guarantee insulation, then insulation between sensing strings is improved, but optical interference and diffraction cause blur, distortion or moiré patterns reducing image quality
Solution Approach 1:
The shielding layer serves as an optical intermediary that has specific optical properties allowing it to block electromagnetic interference while maintaining optical uniformity. The layer's material composition and thickness are designed to minimize optical interference and prevent moiré patterns, thus protecting image quality while preserving insulation.
Solution Approach 2:
The patent optimizes the parameters of the shielding layer, including its thickness, material composition, and optical properties, to achieve a balance between electromagnetic shielding effectiveness and optical transparency. By carefully controlling these parameters, the shielding layer reduces optical interference without compromising its interference-blocking function.
3Adaptability or versatility
If the effective area of capacitive electrode is adjusted to meet customer requirements, then customization flexibility is improved, but the electrode pattern of the sensing layer must be changed increasing manufacturing complexity
Solution Approach 1:
The patent segments the sensing layer into modular components, allowing the effective electrode area to be adjusted by activating or deactivating specific segments rather than redesigning the entire electrode pattern. This segmentation enables flexible customization while maintaining a standardized manufacturing process for the complete sensing layer structure.
Solution Approach 2:
The patent implements a dynamic configuration where the effective electrode area can be adjusted through controllable elements such as switches or variable resistance components integrated into the sensing layer. This dynamic approach allows customization of the effective area without physical changes to the electrode pattern, simplifying manufacturing while providing adaptability.
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
The design effectively shields EMI, reduces optical interference, and enhances image quality by narrowing the intervals on the second sensing layer, providing a flexible effective area for capacitive electrodes while maintaining manufacturing simplicity and cost-effectiveness.
Implementation Method 1
the intervals on the second sensing layer are very narrow to provide an EMI shielding effect
Implementation Method 2
a touch sensor with a widened intervals tends to cause blur, distortion or even a moiré pattern of image shown on a display under the touch sensor because of optical interference and diffraction
Data Source
AI summary
A touch sensor includes an insulative substrate; a first sensing layer, having first sensing strings arranged along a first axis, and a first interval being disposed between every two adjacent first sensing strings; and a second sensing layer, having line paths arranged along a second axis, and a second interval being disposed between every two adjacent line paths. A plurality of the line paths composes a second sensing string. Each second sensing string has an active unit and an inactive unit. The active unit is formed by one or more line paths connected by a crossing line. The line paths of the inactive units are connected to a ground line. The first sensing strings and the second sensing strings are separately orthogonally arranged on two opposite sides of the substrate. The second interval is less than the first interval in width.