Capacitive Sensing Plate for Coating Detection Accuracy
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Solution Overview
Problem
Existing devices for detecting conductive coatings on transparent and translucent media, such as glass, face challenges due to the influence of the surrounding environment's electrical field, which affects capacitance measurements, leading to inaccurate detection and location identification.
Innovation Solution
A capacitive-sensing device that includes a capacitive sensor, an excitation source, a selective indicator, and a capacitive sensing plate, which compensates for environmental interactions by forming a controlled electrical field and using shields to minimize user-induced polarization effects, allowing for precise detection of conductive coatings on non-conductive mediums.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive sensor is used to detect conductive coatings on transparent media, then the detection capability is improved, but environmental capacitance interference causes measurement inaccuracy
Solution Approach 1:
A capacitive sensing plate is introduced as an intermediary element between the capacitive sensor and the environment. This plate serves as a mediator that captures environmental capacitance effects (such as those from user hands or surrounding objects) and provides compensating signals to counteract their interference with the coating detection measurements.
Solution Approach 2:
The system implements feedback by using the capacitive sensing plate to continuously monitor environmental capacitance changes and feeding this information back to adjust the detection measurements. The plate's capacitance variations, caused by environmental factors, are used to compensate for similar variations in the main sensing signal, thereby maintaining measurement accuracy.
2Measurement precision
If environmental capacitance is compensated for using additional sensing plates, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The capacitive sensing plate serves multiple functions: it acts as both an environmental capacitance sensor and a compensating element for the main detection sensor. By making this component multi-functional, the system achieves accurate environmental compensation without proportionally increasing device complexity.
Solution Approach 2:
The system merges the environmental sensing function and the coating detection function into a unified capacitive measurement system. The capacitive sensing plate and the main capacitive sensor work together as an integrated system, sharing common signal processing and control circuitry, which reduces overall complexity compared to having separate independent systems.
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 device provides improved signal resolution and accuracy in detecting the presence and location of conductive coatings on transparent media by accounting for environmental capacitance changes, offering reliable and efficient detection across various glass and gap combinations.
Implementation Method 1
capacitance (which is the ability to store charge) is affected by everything interacting with the electric field that exists between the prior art device and the entire system ground
Implementation Method 2
the total working environment is polarized by the existing electrical field, which leads to an increase or offset in capacitance that is measured
Implementation Method 3
a capacitive sensing plate configured to sufficiently affect the capacitive sensor negatively or positively by a sufficient amount in order to differentiate locations of the coating
Implementation Method 4
the total working environment is polarized by the existing electrical field
Data Source
AI summary
A device for accounting for environmental capacitances caused by an external object when detecting the presence and surface location of an electrically conductive coating on a transparent and/or translucent medium includes: a capacitive sensor that provides multiple capacitances; electronics that are responsive to the capacitances; an excitation source that generates a train of pulses, voltage or current to determine capacitances at the capacitive sensor; a selective indicator; and, a capacitive sensing plate that affects, or is affected by, the pulses, voltage or current from the excitation source.