Capacitance Sensor Electrode Area Variation for Edge Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitance-type touch panels face challenges in accurately detecting objects at the edge and center of the sensor substrate due to varying detection sensitivity, leading to detection errors and difficulties in multi-point detection.
Innovation Solution
The capacitance-type detecting device is designed with detecting electrodes arranged such that capacitance at the edge is greater than at the center, reducing the difference in capacitance variation and sensitivity between low and high sensitivity regions, enabling accurate multi-point detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If detecting electrodes are arranged uniformly across the sensor substrate, then the device structure is simple and easy to manufacture, but detection sensitivity varies significantly between edge and center regions
Solution Approach 1:
The patent applies local quality by varying the area of detecting electrodes based on their position on the sensor substrate. Specifically, electrodes in the edge region have a larger area than those in the center region, creating local differences in electrode properties that compensate for the naturally lower capacitance variation at the edges. This localized adjustment equalizes detection sensitivity across the entire sensor surface while maintaining a relatively simple overall structure.
2Measurement precision
If a threshold value is set based on center region capacitance variation, then center detection accuracy is high, but edge detection fails due to lower capacitance variation
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through position-dependent electrode area design. The larger electrode area at the edges increases the capacitance variation in that region, bringing it closer to the level of the center region. This allows a unified threshold value to effectively detect touches across the entire sensor surface, eliminating the need for region-specific threshold adjustments.
3Reliability
If a threshold value is set based on edge region capacitance variation, then edge detection reliability improves, but center detection produces false positives due to higher capacitance variation
Solution Approach 1:
The patent eliminates the need for region-specific threshold values by applying local quality through varied electrode areas. The increased electrode area at the edges enhances capacitance variation there, while the smaller center electrodes maintain appropriate capacitance variation at the center. This balancing act creates uniform detection sensitivity across the sensor, allowing a single threshold to accurately detect touches anywhere on the surface without false positives or negatives.
4Area of stationary object
If the sensor substrate size is increased to expand the detection area, then the coverage area increases, but the difference in detection sensitivity between edge and center regions becomes more pronounced
Solution Approach 1:
The patent addresses this contradiction by applying local quality through a systematic variation of electrode areas across the sensor substrate. As the sensor size increases, the edge electrodes maintain larger areas than center electrodes, compensating for the increased distance from adjacent electrodes and the reduced capacitance variation that would otherwise occur in larger formats. This localized adjustment maintains uniform detection sensitivity across expanded sensor surfaces.
Solution Approach 2:
The patent employs asymmetry by deliberately creating asymmetric electrode area distributions across the sensor substrate. Rather than using uniform electrodes, the design introduces asymmetric variations where edge electrodes have different (larger) areas than center electrodes. This asymmetric configuration compensates for the symmetric geometric constraints of the sensor layout, equalizing detection sensitivity across the entire surface regardless of size.
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 arrangement reduces the difference in detection sensitivity across the sensor substrate, allowing for precise detection of objects approaching both low and high sensitivity regions, thereby enhancing the accuracy of multi-point detection.
Implementation Method 1
a capacitance is formed between adjacent electrodes
Implementation Method 2
some of the electric field lines formed between a plurality of detecting electrodes are drawn out by the finger and the capacitance formed between the detecting electrodes is reduced
Data Source
AI summary
A capacitance-type detecting device according to an embodiment of the invention includes a plurality of detecting electrodes that are provided on a sensor substrate such that capacitance is formed between adjacent electrodes. Capacitance formed in a corner detection region in which the detection sensitivity of the sensor substrate is relatively low is more than that formed in a central detection region in which the detection sensitivity is relatively high.