Inductive Proximity Sensing with Mounting Fitting Compensation
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Solution Overview
Problem
Existing inductive proximity sensors face challenges in reducing the influence of mounting metal fittings, as previous methods either have limited effectiveness or are sensitive to temperature changes in the environment, making it difficult to construct a robust sensor that can accurately detect metallic objects at varying distances.
Innovation Solution
The proposed solution involves a proximity sensor with multiple detection coils and a control unit that extracts and compensates for components caused by both the mounting metal fitting and the detection object, using a method that involves generating magnetic fields, detecting voltages or currents, and performing compensation computations to accurately sense the presence or position of the detection object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If detection sensitivity of the proximity sensor is set to be very high, then the sensor can detect metallic objects at long distances, but the sensor reacts to the mounting metal fitting which causes false detection
Solution Approach 1:
The patent segments the detection signal into multiple frequency components. The detection coil generates a magnetic field at a specific frequency, and the reception circuit detects voltage components at this frequency. By analyzing the frequency spectrum and separating the mounting fitting response from the detection object response, the system can distinguish between false signals and valid detection signals, enabling high sensitivity without false positives from mounting structures.
Solution Approach 2:
The patent employs feedback mechanisms where the control unit analyzes the detection results and adjusts the excitation frequency or compensation parameters accordingly. The system continuously monitors the voltage components detected by the reception circuit and uses this information to refine the detection process, compensating for the mounting metal fitting's influence while maintaining high detection sensitivity for actual objects.
2Reliability
If a metallic film is used to reduce the influence of mounting metal fitting, then the fitting property with metal mounting plate is improved, but the effect is limited to specific materials and does not provide general solution
Solution Approach 1:
The patent replaces the mechanical/physical approach of using metallic films with electromagnetic field-based detection and signal processing. Instead of modifying the sensor's physical interface with mounting structures, the system uses frequency-domain analysis and control unit processing to distinguish between mounting fitting signals and detection object signals. This electronic/software-based solution provides universal applicability across different mounting materials without requiring material-specific adaptations.
3Device complexity
If Q values of coils are used for detection, then the detection method is simplified, but the Q values fluctuate significantly due to temperature changes making the sensor unreliable in varying environments
Solution Approach 1:
The patent changes the detection parameter from Q value (which is highly temperature-sensitive) to frequency-domain voltage components. The reception circuit detects voltage components at the excitation frequency, and the control unit analyzes these components to determine detection object presence. Frequency-based detection is inherently more stable against temperature variations than Q value measurements, as the excitation frequency and its harmonic components remain relatively constant across temperature ranges, providing reliable detection in varying environmental conditions.
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 approach effectively reduces the influence of mounting metal fittings, allowing for increased detection distances and improved accuracy in sensing metallic objects, even in varying environmental conditions.
Implementation Method 1
a plurality of detection coils for generating a magnetic field
Implementation Method 2
a reception circuit that detects voltages generated at both ends of the detection coils or currents flowing in the detection coils due to the supply of the current
Data Source
AI summary
A proximity sensor includes a transmission circuit that supplies a current to each of detection coils, a reception circuit that detects voltages generated at both ends of the coils or currents flowing in the coils due to the supply of the current for each of the coils, a control unit that senses the presence or position of a detection object using a detection result of the reception circuit, and an output unit that outputs a sensing result of the control unit. The control unit extracts a first component caused by a mounting fitting for mounting the proximity sensor on a support member and a second component caused by the detection object from the detection result of the reception circuit. The control unit compensates the second component using the first component. The control unit senses the presence or position of the detection object on the basis of the compensated second component.