Capacitive Touch Panel Conductive Layer Static Charge Distribution
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Solution Overview
Problem
Capacitive touch sensing systems are affected by static electric charges, which can lead to inaccurate detection of objects due to charge accumulation on the touch panel surface, especially in dry environments where atmospheric discharge is hindered, causing saturation of sensing circuits and failure to detect fingers or other objects.
Innovation Solution
A touch panel design incorporating a conductive layer closer to the object than the touch electrodes, which distributes static electric charges across the surface, reducing interference and improving sensing accuracy through a capacitance sensing method involving connection to a direct current potential and subsequent floating of the conductive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional touch panel structure is used without a conductive layer, then the structure is simpler and manufacturing is easier, but static electric charges accumulate on the surface causing sensing errors and circuit saturation
Solution Approach 1:
The conductive layer is integrated within the existing touch panel structure, nested between the dielectric layer and the touch electrodes. This nested configuration allows the conductive layer to perform charge distribution function while maintaining the compact multi-layer structure of the touch panel, avoiding significant structural complexity increase
Solution Approach 2:
The conductive layer acts as an intermediary element between the dielectric layer and the touch electrodes. It mediates the static charge accumulation problem by providing a conductive path that distributes charges across the surface, preventing charge buildup that would otherwise directly affect the sensing electrodes and cause detection errors
2Reliability
If the conductive layer is placed closer to the touch electrodes, then charge distribution is more effective, but the structure becomes more complex and manufacturing harder
Solution Approach 1:
The patent optimizes the position of the conductive layer along the vertical dimension (z-axis) of the touch panel structure. By placing the conductive layer at a specific distance from the touch electrodes in the vertical dimension, it achieves effective charge distribution while maintaining manufacturability. The vertical positioning allows charge distribution functionality without requiring complex lateral arrangements or difficult alignment procedures during manufacturing
3Measurement precision
If capacitance sensing is performed continuously, then detection accuracy is maintained, but static charges accumulate causing saturation and detection failure
Solution Approach 1:
The system employs periodic switching of the conductive layer between connected and floating states. During the connected phase, charges are distributed to prevent accumulation. This periodic action maintains detection accuracy over time by preventing charge buildup that would lead to circuit saturation and detection failure
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 solution effectively reduces errors in capacitance sensing by distributing static charges, enhancing the accuracy of detecting external objects and preventing sensing circuit saturation, particularly in dry environments.
Implementation Method 1
a conductive layer...distributes static electric charges across the surface
Implementation Method 2
perform capacitance sensing an external object approaching or touching the touch panel via the first and the second electrodes
Data Source
AI summary
A touch panel, sequentially comprising: a conductive layer, a dielectric layer; and at least one layer of touch electrodes, which comprises multiple first electrodes in parallel to a first axis and multiple second electrodes in parallel to a second axis, wherein the first and the second electrodes connects to a touch sensitive processing apparatus, respectively, wherein the touch sensitive processing apparatus detects an external object approaching or touching the touch panel via the first and the second electrodes, wherein the conductive layer is closer to the external object than the at least one layer of touch electrodes.