Proximity Sensor Frequency Switching Against Magnetic Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional proximity sensors face inaccuracies in determining the approach to an electrically conductive body due to interfering alternating magnetic fields with the same frequency, often caused by sources like electric motors.
Innovation Solution
A proximity sensor system that emits an alternating magnetic field with a selected frequency, uses a detection mechanism to identify frequencies outside a predefined band with high amplitude, and employs a blocking circuit to exclude these frequencies, allowing the selection of a repetition frequency that differs from both the original and interfering fields, ensuring reliable detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed frequency is used for the alternating magnetic field, then the sensor operation is simple and stable, but the measurement precision deteriorates due to interfering magnetic fields with the same frequency
Solution Approach 1:
The patent applies dynamics by making the frequency of the alternating magnetic field variable rather than fixed. The control logic dynamically adjusts the frequency based on detected interfering fields, allowing the sensor to adapt to different environmental conditions and avoid frequency conflicts with electric motors or other interference sources.
Solution Approach 2:
The patent changes the frequency parameter of the alternating magnetic field based on detection results. When interfering fields are detected, the system modifies the frequency parameter to a new value that avoids the interference, thereby maintaining measurement precision without requiring complex hardware modifications.
2Measurement precision
If frequency hopping is implemented to avoid interference, then the measurement precision improves, but the loss of time increases due to frequency switching
Solution Approach 1:
The patent implements preliminary action by performing frequency detection and selection before the actual measurement process. The control logic identifies suitable frequencies in advance and stores them, so when measurement begins, the system can quickly switch to a pre-selected frequency without significant time loss.
Solution Approach 2:
The patent uses periodic action by implementing continuous monitoring of the environment for interfering fields and periodically adjusting the frequency as needed. This allows the system to maintain optimal measurement conditions while minimizing the impact of frequency changes through rhythmic, predictable operation cycles.
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
Enables accurate determination of the approach to an electrically conductive body even in the presence of interfering magnetic fields by consistently selecting frequencies that differ from the interfering signals, thus minimizing interference.
Implementation Method 1
a transmitter arrangement with which an alternating magnetic field is emitted. The alternating magnetic field has a frequency corresponding to a selected frequency
Implementation Method 2
The emitted alternating magnetic field induces an alternating current, also known as an eddy current, in the conductive object. This eddy current results in an alternating magnetic field with the same frequency as the emitted alternating magnetic field.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The proximity sensor has a transmitting arrangement (12) for emitting an alternating magnetic field (16) with a selected frequency and a receiving arrangement (14) for detecting another alternating magnetic field (20). A detection unit is provided for detecting one or multiple frequencies of the detected alternating magnetic field which lies outside of a predetermined frequency band having the selected frequency and has an amplitude value above a predetermined threshold value. An independent claim is included for a method for determining the proximity to an electrically conductive body.