Electrostatic Capacitance Position Sensor Ground Region Design
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Solution Overview
Problem
Electrostatic capacitance-type position detection devices face accuracy issues due to increased electrode pitch, leading to sensitivity variations and inversion sensing errors, which degrade position detection performance.
Innovation Solution
The configuration includes first and second electrodes arranged in a substrate with a ground electrode forming a ground region around the intersection points, where the first and second electrodes are positioned on the outer sides of the ground region, reducing sensitivity peaks and variations, and enhancing detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electrode pitch is increased to reduce the number of electrodes and lower cost, then the device complexity and cost are reduced, but the position detection accuracy deteriorates due to sensitivity variation
Solution Approach 1:
The patent introduces ground regions with different ground capacitances at different locations. Specifically, ground regions adjacent to electrode intersections have larger ground capacitance values than other ground regions. This local differentiation compensates for the sensitivity variations caused by increased electrode pitch, maintaining uniform detection characteristics across the sensor surface while using fewer electrodes.
Solution Approach 2:
The patent changes the ground capacitance parameter spatially across the sensor surface. By assigning different ground capacitance values to different ground regions based on their proximity to electrode intersections, the system compensates for the non-uniform sensitivity distribution that arises from increased electrode pitch, thereby maintaining detection accuracy.
2Device complexity
If the electrode pitch is increased to reduce the number of electrodes, then the device complexity is reduced, but the sensitivity variation due to position becomes large
Solution Approach 1:
The patent applies local quality by making ground regions adjacent to electrode intersections different from other ground regions. The ground capacitance of regions near intersections is intentionally increased to compensate for the enhanced sensitivity at those locations, creating a uniform overall sensitivity distribution across the sensor surface despite the reduced electrode density.
Solution Approach 2:
The patent achieves equipotentiality in terms of sensitivity distribution by carefully designing the ground capacitance values. By equating the total capacitance (sensing capacitance plus ground capacitance) across different regions, the system ensures uniform detection sensitivity throughout the sensor surface, even with fewer electrodes spaced farther apart.
3Ease of manufacture
If the electrode pitch is increased to reduce cost, then the manufacturing cost is reduced, but inversion sensing errors increase
Solution Approach 1:
The patent addresses inversion sensing errors by introducing local quality variations in ground capacitance. Ground regions adjacent to electrode intersections have larger ground capacitance values, which compensates for the exaggerated sensitivity at intersection points. This prevents the inversion sensing errors that would otherwise occur with increased electrode pitch by maintaining uniform sensitivity characteristics.
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 configuration effectively suppresses sensitivity variations and improves position detection accuracy even with increased electrode pitch, reducing inversion sensing errors and enhancing overall detection sensitivity.
Implementation Method 1
electrostatic capacitance between the corresponding drive electrode and the corresponding detection electrode is reduced by bringing a finger close thereto
Implementation Method 2
while largely functioning as a ground conductor for reducing electrostatic capacitance between the corresponding drive electrode and the corresponding detection electrode
Implementation Method 3
the pointing body such as a finger also largely functions as a floating conductor that increases the electrostatic capacitance between the corresponding drive electrode and the corresponding detection electrode
Data Source
AI summary
In an electrostatic capacitance-type position detection device, a corresponding ground region is formed at an intersection point between a corresponding first virtual center line and a corresponding second virtual center line, and a corresponding detection electrode and a corresponding drive electrode are disposed on the outer side of the relevant ground region. The detection electrodes each include a first electrode line and a second electrode line that extend in a second direction and are disposed so as to sandwich therebetween the ground regions from a first direction. The drive electrodes are each configured by arranging electrode patterns in order in the first direction. The electrode patterns each include a third electrode line that extends in the second direction, and a fourth electrode line and a fifth electrode line that are located on both respective ends of the third electrode line and extend in the first direction.