Shielded Coil Sensor Layout to Prevent Eddy Current Noise
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Solution Overview
Problem
Proximity sensors face malfunctions due to noise interference from external electromagnetic waves, which affects detection accuracy when a shield is used to prevent noise penetration, as eddy currents generated in the shield can overlap with the electric signal.
Innovation Solution
A sensor design that includes a shield with a separator, such as an insulating spacer, to prevent noise from the shield's eddy current from reaching the coil, enhancing noise resistance and detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield part is arranged on the front surface of the core to cover the coil assembly, then noise penetration from outside is suppressed, but eddy current generated in the shield part affects the coil and causes malfunction
Solution Approach 1:
The patent introduces a separator as an intermediary component positioned between the shield part and the coil assembly. This separator prevents direct contact while allowing the shield to block external noise, thereby eliminating the eddy current noise generated when the shield directly contacts the coil. The separator acts as a mediator that resolves the conflict between noise suppression and eddy current prevention.
Solution Approach 2:
The patent segments the shield part and coil assembly into separate components with a gap between them, filled by the separator. This segmentation prevents the formation of continuous eddy current paths in the shield while maintaining the shield's noise-blocking function. The separation divides the system into distinct functional zones that do not interfere with each other electrically.
2Measurement precision
If the coil assembly is arranged as close to the front end of the case body as possible to increase detection sensitivity, then detection sensitivity is improved, but the coil assembly comes into direct contact with the shield part causing noise interference
Solution Approach 1:
The separator serves as an intermediary that enables the coil assembly to be positioned close to the front end for high detection sensitivity while preventing direct contact with the shield part. This intermediary component allows the coil to operate in the optimal position without suffering from eddy current noise, thus resolving the contradiction between sensitivity and noise interference.
3Reliability
If the shield part covers the front surface of the coil assembly to prevent noise penetration, then noise resistance is improved, but the eddy current in the shield overlaps the electric signal flowing through the coil
Solution Approach 1:
The separator acts as a mediator that allows the shield to maintain its noise-resistant function while preventing the generation of eddy current noise that would overlap with and degrade the electric signal. By introducing this intermediary, the system achieves both high noise resistance and high signal quality without compromise.
Solution Approach 2:
The patent segments the electromagnetic environment by creating an electrical gap between the shield and coil through the separator. This segmentation prevents the coupling of eddy current noise into the signal path while maintaining the shield's ability to block external noise, thus preserving signal integrity while ensuring noise resistance.
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 separator effectively reduces noise interference, improving the sensor's detection accuracy and stability by separating the shield and coil surfaces, thereby enhancing noise resistance and maintaining detection performance.
Implementation Method 1
a shield at least one portion of which is arranged on the end side of the internal space with respect to the coil part and which suppresses penetration of noise from outside of the housing
Implementation Method 2
an eddy current generated in this shield part due to noise from the outside of the housing may affect the coil
Data Source
AI summary
This sensor includes: a housing 10 which houses an electronic component in the internal space; a detection unit 40 which has a coil 42 and a core 41 that houses the coil 42 and which is arranged on the end side in the internal space; a substrate 30 which is arranged more inside the internal space than the detection unit 40 and on which a circuit electrically connected to the coil 42 is provided; a first shield 451 at least one portion of which is arranged further on the end side in the internal space than the detection unit 40 and which suppresses the penetration of noise from outside of the housing 10; and a spacer 51 which is positioned between the first shield 451 and the detection unit 40 and which separates the surfaces of the first shield 451 and the detection unit 40 that face each other.