Current Sensor Signal Line Orientation Reduces Capacitive Coupling
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Solution Overview
Problem
Current sensors with Hall ICs experience output errors due to capacitive coupling and electromagnetic noise from terminals and signal lines, which are not effectively mitigated by existing designs.
Innovation Solution
A current sensor design featuring a magnetic sensor element with signal lines connected to a wiring board in a direction intersecting the bus bar, increasing distance and reducing capacitive coupling, and incorporating a shield to block electromagnetic noise, with a grounded ground line to cancel out noise effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If terminals and signal lines are connected parallel to the bus bar, then electrical connection is simplified, but capacitive coupling increases causing output errors
Solution Approach 1:
The patent changes the spatial arrangement of signal lines from parallel to intersecting orientation relative to the bus bar. This dimensional change in layout reduces the overlapping area between signal lines and bus bar, thereby minimizing capacitive coupling while maintaining electrical connection functionality.
2Length of moving object
If signal lines are disposed near the bus bar, then connection distance is reduced, but electromagnetic noise superposition increases
Solution Approach 1:
The patent repositions signal lines from a configuration near the bus bar to an intersecting configuration that extends away from the bus bar. This spatial rearrangement increases the distance between signal lines and bus bar, reducing electromagnetic noise superposition while maintaining acceptable connection lengths.
3Measurement precision
If Hall IC is inserted in the gap of the core, then magnetic flux detection is enabled, but capacitive coupling with terminals occurs
Solution Approach 1:
The patent extracts the signal transmission function from the Hall IC package by providing separate signal lines that extend from the Hall IC to external terminals. This separation removes the capacitive coupling path between the Hall IC and external circuitry, allowing magnetic flux detection to function independently of capacitive interference.
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 design significantly reduces output errors by minimizing capacitive coupling and electromagnetic interference, ensuring more accurate signal transmission.
Implementation Method 1
When a measured current flows through the bus bar 111, a magnetic field is generated around the bus bar 111
Implementation Method 2
a Hall element as a magnetic sensor element... able to detect a magnetic flux passing through a magnetosensitive surface 113a of the Hall IC 113
Implementation Method 3
incorporating a shield to block electromagnetic noise
Data Source
AI summary
A current sensor according to the present invention includes a bus bar, a magnetic sensor element disposed so as to face the bus bar, a wiring board on which the magnetic sensor element is provided, and a signal line electrically connected to the magnetic sensor element. The wiring board includes a base portion facing the bus bar and an extending portion extending from the base portion, and the signal line is connected to the extending portion and provided in a direction intersecting the wiring board.