Magnetic Displacement Sensor for EMI-Resistant Battery Electrode Calipers
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Solution Overview
Problem
Existing non-contact thickness measurement systems are inadequate for accurately measuring conductive materials like coated substrates used in fabricating anodes and cathodes for lithium ion batteries, as they are sensitive to electromagnetic interference and lack the required accuracy and repeatability.
Innovation Solution
A high accuracy and stability magnetic absolute displacement sensor system using dual magnetic sensors to measure the distance between scanner heads, which generates a magnetic field and analyzes electrical signals to determine thickness, capable of filtering out interfering magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If eddy current sensors or laser calipers are used for non-contact thickness measurement, then measurement capability is provided, but measurement precision deteriorates when measuring conductive materials due to electromagnetic interference
Solution Approach 1:
The patent replaces electromagnetic sensing mechanisms (eddy current sensors, laser calipers) with a mechanical absolute encoding system. The absolute encoder uses mechanical movement of a scale relative to a read head to directly measure displacement, eliminating electromagnetic fields from the measurement process entirely. This mechanical substitution resolves the electromagnetic interference problem while maintaining measurement precision.
Solution Approach 2:
The patent introduces a mechanical scale as an intermediary element between the measurement system and the object being measured. The absolute encoder reads positional information from this mechanical scale, which physically couples the measurement system to the moving component without requiring electromagnetic fields. This intermediary mechanism enables precise measurement of conductive materials without electromagnetic interference.
2Reliability
If electromagnetic sensors are used to measure distance between scanner heads, then distance measurement is achieved, but reliability deteriorates in the presence of interfering magnetic fields
Solution Approach 1:
The patent replaces electromagnetic distance measurement systems with a mechanical absolute encoding system. The absolute encoder uses direct mechanical coupling between the moving scanner head and the encoding scale to determine position, eliminating susceptibility to magnetic field interference. This mechanical approach ensures reliable operation in environments with varying magnetic fields.
3Manufacturing precision
If non-contact measurement methods are used for coated substrates, then contactless measurement is achieved, but manufacturing precision deteriorates due to inability to accurately measure conductive materials
Solution Approach 1:
The patent replaces electromagnetic non-contact measurement methods with a mechanical absolute encoding system that can accurately measure the position of scanner heads measuring conductive coated substrates. The mechanical system is universally applicable to all materials regardless of electrical conductivity, enabling precise coating thickness measurements on metal and other conductive substrates.
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
Provides accurate thickness measurements with better than 1 micron precision, suitable for quality control in lithium ion battery production, while being resistant to electromagnetic interference.
Implementation Method 1
a source of a magnetic field that is positioned in a first enclosure
Implementation Method 2
a first magnetic sensor that is configured to measure the magnetic field and a second magnetic sensor that is configured to measure the magnetic field
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An accurate and stable displacement sensor that reads through coated metal substrates achieves better than one micron accuracy includes: an electromagnetic coil positioned in a first enclosure; (ii) means for generating a magnetic field from the electromagnetic coil; (iii) a second enclosure which is spaced apart from the first enclosure, wherein the second enclosure includes dual magnetic sensors, such as fluxgate sensors, that are configured to measure the magnetic field; and (iv) means for calculating the separation between the operative surfaces of the enclosures from magnetic field measurements. A permanent magnet can be used instead of the electromagnetic coil and associated driving energy source. A precise displacement measurement is given by a mathematical function (such as the ratio or difference) of the two magnetic sensors demodulated signals. The displacement sensor can be mounted on a maneuverable C-frame to monitor the caliper of anodes and cathodes produced for lithium ion batteries.