Capacitive Finger Sensing with Paired Plates for High Sensitivity
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Solution Overview
Problem
Existing finger sensing devices require a high number of individual capacitive plates and sensors to achieve high sensitivity, which is costly and inefficient.
Innovation Solution
A finger sensing device using a pair of conductive plates, where the area between the finger and one plate increases and the area between the finger and the other plate decreases as the finger moves, with capacitance detectors measuring these changes to determine finger position, acceleration, and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high number of capacitive plates and sensors are used to achieve high sensitivity, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple sensing functions (position detection in multiple directions, pressure sensing, acceleration detection) into a single capacitive sensor structure. By using one capacitive sensor to measure capacitance changes relative to multiple conductive plates with different geometric configurations, the system achieves high sensitivity without requiring multiple separate sensors for each function, thus reducing device complexity while maintaining measurement precision
Solution Approach 2:
The capacitive sensor serves multiple functions simultaneously: it detects finger position in both x and y directions, measures applied pressure, and detects acceleration. This multi-functional capability eliminates the need for separate sensors for each measurement type, resolving the contradiction between achieving high sensitivity through multiple measurement capabilities and reducing device complexity by using a single sensor
2Measurement precision
If a high number of capacitive plates and sensors are used to achieve high sensitivity, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent merges the functionality of multiple expensive components (multiple capacitive plates and sensors) into a single integrated capacitive sensor that interacts with multiple conductive plates. This consolidation significantly reduces the bill of materials and manufacturing complexity, making the device more cost-effective while maintaining the sensitivity required for accurate finger gesture detection
Solution Approach 2:
Instead of using multiple physical capacitive sensors, the patent uses a single capacitive sensor that electronically distinguishes between signals from different conductive plates through pattern recognition and signal processing. This virtual multiplication of sensing capability without physical multiplication of components reduces cost while maintaining measurement precision
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 allows for accurate determination of finger position, acceleration, and pressure with minimal capacitive plates and sensors, reducing costs while maintaining high sensitivity.
Implementation Method 1
A first capacitance detector is coupled to the first conductive plate for measuring a first capacitance between the finger and the first conductive plate
Data Source
AI summary
A finger sensing device includes a first conductive plate, wherein the area between the finger and the first conductive plate increases in response to the finger moving in a first direction proximate the first conductive plate. A second conductive plate is located proximate the first conductive plate, wherein the area between the finger and the second conductive plate decreases in response to the finger moving in the first direction proximate the second conductive plate. A first capacitance detector is coupled to the first conductive plate for measuring a first capacitance between the finger and the first conductive plate. A second capacitance detector is coupled to the second conductive plate for measuring a second capacitance between the finger and the second conductive plate.