Shield Electrodes in Capacitive Touch Sensors
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Solution Overview
Problem
Capacitive touch sensors face interference from other components, leading to distorting effects on self-capacitance measurements, which affects the precision and linearity of touch and proximity detection, especially when dealing with faster-moving objects.
Innovation Solution
Incorporating shield electrodes between proximity electrodes and the display to reduce interference, allowing for faster switching between touch and proximity modes without additional layers that would degrade optical performance or increase complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional shield layers are added to reduce interference, then measurement precision improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the shield electrode function with existing display structure components, specifically integrating the shield into the display's ground plane or backplane. This merging approach provides interference shielding without adding separate dedicated shield layers, thus improving measurement precision while avoiding increased device complexity and manufacturing cost.
Solution Approach 2:
The patent makes existing display structure components serve dual functions: the display's ground plane or backplane simultaneously performs its original electromagnetic shielding function and serves as the capacitive touch sensor's shield electrode. This multi-functionality eliminates the need for additional shield layers while maintaining detection precision.
2Measurement precision
If additional shield layers are added to reduce interference, then measurement precision improves, but manufacturing cost increases
Solution Approach 1:
The patent merges the shield electrode with existing display manufacturing structures, allowing the same ground plane or backplane to serve both display and touch sensor functions. This eliminates the need for separate shield electrode fabrication processes, reducing manufacturing steps and production cost while maintaining precision.
Solution Approach 2:
The patent enables existing display components to perform multiple functions simultaneously, including serving as the shield electrode for the capacitive touch sensor. This multi-functionality reduces the total component count and manufacturing complexity, thereby lowering production costs while achieving the required measurement precision.
3Speed
If switching between touch and proximity modes is accelerated, then response speed improves, but measurement precision deteriorates due to interference
Solution Approach 1:
The patent applies preliminary shielding by integrating the shield electrode into the display structure before touch sensor operation begins. This pre-configured shield continuously mitigates interference from display components and other sources, allowing fast mode switching without sacrificing measurement precision, as the shielding is always in place rather than being activated or deactivated with mode changes.
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 solution enhances the precision and linearity of touch and proximity measurements by mitigating interference, enabling more accurate detection of object positions, particularly for faster-moving objects, while maintaining optical performance and reducing production costs.
Implementation Method 1
Incorporating shield electrodes between proximity electrodes and the display to reduce interference
Implementation Method 2
When an object touches or comes within proximity of the surface of the capacitive touch screen, a change in capacitance may occur within the touch screen at the location of the touch or proximity
Data Source
AI summary
In certain embodiments, a touch sensor includes a plurality of first electrodes, and a plurality of second electrodes. The plurality of second electrodes are separated from the plurality of first electrodes by an insulator and are operable, when operated by a controller, to capacitively couple with one or more first electrodes across the insulator. The touch sensor also includes a touch panel, a plurality of proximity electrodes, and a plurality of shield electrodes. Each shield electrode is associated with a respective proximity electrode of the plurality of proximity electrodes such that each shield electrode substantially surrounds its respective proximity electrode from a perspective orthogonal to a surface of the touch panel.