Circuit Board Arrangement for Eddy Current Cancellation
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Solution Overview
Problem
In hybrid imaging devices like PET/MR scanners, the interaction between changing magnetic fields and circuit board arrangements causes eddy currents and induced voltages, leading to image disturbances and potential damage to electronics, especially in compact designs where PET detectors and electronics are close to gradient coils.
Innovation Solution
The circuit board arrangement is designed with conductor track sections forming structure sections that induce equal and opposite voltages and currents, with these sections aligned at specific angles to cancel out induced effects, using a zigzag routing pattern and multilayered configuration to minimize eddy currents and voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If PET detectors and electronics are placed close to gradient coils in compact hybrid imaging devices, then device size is reduced and imaging efficiency is improved, but eddy currents and induced voltages increase causing image disturbances and potential damage to electronics
Solution Approach 1:
The circuit board is divided into multiple conductor track sections that form structure sections. These structure sections are arranged in pairs where adjacent sections induce equal and opposite voltages and currents, causing them to cancel each other out. This segmentation approach reduces the net eddy currents and induced voltages while maintaining the compact device configuration.
Solution Approach 2:
The conductor tracks are designed with specific asymmetric routing patterns where structure sections within pairs have different spatial orientations and positions relative to the gradient coils. This asymmetric arrangement ensures that while individual sections experience different magnetic field strengths, their induced voltages and currents are equal in magnitude but opposite in direction, achieving cancellation.
2Ease of manufacture
If conventional conductor track routing is used in circuit boards placed in changing magnetic fields, then manufacturing is simple, but eddy currents and induced voltages cause image disturbances and electronics damage
Solution Approach 1:
The circuit board routing is segmented into discrete conductor track sections that form structure sections. Each structure section is designed to work in pairs, where the segmentation allows for systematic cancellation of induced electromagnetic effects while maintaining manufacturability through standardized routing patterns.
Solution Approach 2:
The design converts the harmful effect of induced voltages and currents into a beneficial cancellation mechanism. By strategically arranging structure sections in pairs with specific geometric relationships, the induced electromagnetic effects from each section are transformed into opposing forces that neutralize each other, turning potential damage into a protective mechanism.
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 design effectively reduces eddy currents and induced voltages, preventing image disturbances and component damage, while maintaining a compact and efficient imaging device configuration.
Implementation Method 1
the geometric course of the conductor tracks is chosen such that a change in the magnetic field of the magnet arrangement induces equal and opposite voltages and/or currents in the two structure sections of each structure section pair
Implementation Method 2
the gradient fields can furthermore be altered and thus disturbed by currents induced owing to these gradient fields on conductive structures
Data Source
AI summary
A magnet arrangement arranged radially around a sample volume generates a changing magnetic field B with a z-direction component. A circuit board arrangement (6;14) is arranged radially within the magnet arrangement and has electrical conductor tracks (7; 12) divided into conductor track sections (10), at least two adjoining ones of which form a structure section (11a, 11b) spanning an area (A1, A2). For each conductor track (7; 12), two structure sections (11a, 11b) respectively form a structure section pair (11), wherein the conductor tracks are arranged on the circuit board arrangement (6; 14) such that equal and opposite voltages and/or currents are induced by a change in the magnetic field B of the magnet arrangement in the two structure sections of each structure section pair. As a result, eddy currents and resultant interference in the circuit board and the components thereof are avoided or at least minimized.