Proximity Sensor Core Design for Sensitivity and Interference
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Solution Overview
Problem
Existing proximity sensors have limitations in sensitivity and design, requiring alternative core designs that can enhance performance.
Innovation Solution
A compact sensor core design using a sheet of high relative permeability material with specific bends and configurations for the head, leg, and foot portions, allowing for efficient magnetic field generation and reduced flux linkage, along with the option of a conductive shield to minimize interference from non-target objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a traditional core design with multiple separate pieces is used, then the structural strength is improved, but the device complexity increases and manufacturing precision requirements increase
Solution Approach 1:
The patent combines multiple separate core pieces (head, legs, and feet portions) into a single integrated core structure made from one piece of high permeability material. This merging eliminates the need for separate components and their associated joints, thereby reducing device complexity while maintaining structural integrity through the continuous magnetic path provided by the single-piece construction.
Solution Approach 2:
The single-piece core structure serves multiple functions simultaneously: it provides the magnetic circuit path, structural support, and defines the geometric configuration for coil placement. This multi-functionality reduces the need for additional structural components, simplifying the overall device design while maintaining the necessary mechanical strength.
2Manufacturing precision
If a single sheet of material is used to form the core, then the manufacturing precision is improved, but the structural strength may be reduced
Solution Approach 1:
The patent specifies particular geometric parameters for the single-sheet core structure, including the thickness-to-width ratio, the dimensions of head/leg/foot portions, and the angles of bends. By optimizing these parameters, the design achieves both manufacturing precision (through a single fabrication process) and structural strength (through appropriate dimensional relationships that distribute mechanical loads along the magnetic circuit path).
3Power
If the core is made with larger dimensions, then the magnetic field generation is improved, but the sensitivity to external metal objects increases
Solution Approach 1:
The patent creates different local geometries within the core structure: a concentrated head portion for strong local magnetic field generation, extended leg portions for flux distribution, and spaced foot portions for target sensing. This local differentiation allows the core to generate sufficient magnetic field power in the sensing region while the distributed geometry reduces the overall susceptibility to external metal objects by avoiding large continuous magnetic surfaces.
4Power
If the leg portions extend across the full width of the head, then the magnetic flux linkage is improved, but the susceptibility to interference from non-target objects increases
Solution Approach 1:
The patent segments the leg portions so that they extend across only portions of the head width rather than the full width. This segmentation creates discrete magnetic flux paths that are more controlled and localized. The spaced arrangement of legs and feet portions creates a magnetic circuit that is less susceptible to interference from non-target objects while maintaining sufficient flux linkage for effective target detection.
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 new core design improves sensitivity and reduces susceptibility to external metal objects, providing a more effective proximity sensing solution.
Implementation Method 1
a sheet of high relative permeability material having a thickness that is less than a width and length of the sheet of material
Implementation Method 2
The coil assemblies 118 are provided (one coil assembly per leg and foot) through which current is passed to create the magnetic field in combination with the core 120
Implementation Method 3
As a magnetic object is moved towards the core assembly, a distance is reached where the magnetic field of the object finds the core to be the smallest reluctance path. As a result, the flux of the filed enters the core
Data Source
Figure 1~2
Figure 3
Figure 4a
AI summary
A proximity sensor core for a proximity sensor is provided. The core is made from a sheet of high permeability material that has a thickness that is less than a width and length of the sheet of material. The sheet of material is cut or shaped such that it has a head portion extending across a width of the sheet of material and the head has a first length. First and second leg portions extend for a second length from the same edge of the head portion. Each of the first and second leg portions extend across a portion of the width of the head portion. First and second foot portions extend for a third length from the respective first and second leg portions. The first and second foot portions have the same width as the respective leg portions In the basic design, the sheet of material comprises a first bend between each of the first and second foot portions and the respective first and second leg portions so that the first and second foot portions extend generally perpendicular to the respective first and second leg portions.