Inductive Proximity Switch With Reference Resonant Circuit Compensation
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Solution Overview
Problem
Existing inductive proximity switches face challenges in effectively compensating for environmental parameters like temperature, requiring significant additional circuitry to maintain accuracy, especially at high switching distances where signal changes are comparable to temperature-induced effects.
Innovation Solution
The implementation of a proximity switch utilizing a signal resonant circuit and a reference resonant circuit, with a multiplexer circuit to alternately activate them, allowing for the detection of target position and vibration parameters while isolating environmental influences, thereby generating a control signal that compensates for temperature and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature compensation circuitry is added to compensate for environmental parameters, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system is segmented into two independent resonant circuits: a signal resonant circuit exposed to the measurement environment and a reference resonant circuit isolated from it. Each circuit operates independently and can be processed separately through time-multiplexed measurement, allowing environmental effects to be isolated and compensated without requiring complex integrated compensation circuitry.
Solution Approach 2:
A reference resonant circuit is created as a copy of the signal resonant circuit, with identical components and characteristics. This reference circuit is isolated from environmental influences and serves as a baseline for comparison. By measuring the difference between the copy (reference) and the original (signal), environmental effects are eliminated while maintaining measurement precision.
2Speed
If multiple resonant circuits are measured simultaneously, then measurement speed is improved, but interference between circuits increases
Solution Approach 1:
Instead of simultaneous measurement, the system employs periodic action by time-multiplexing the measurement process. The measurement alternates between the signal resonant circuit and the reference resonant circuit in sequential periods. This periodic switching eliminates mutual interference between circuits while maintaining adequate measurement speed through rapid alternation and efficient use of oscillation 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
This approach simplifies and robustly compensates for interference influences, reducing the need for extensive circuitry and maintaining accuracy by isolating target-induced changes from environmental effects, thus enhancing the stability of the proximity switch.
Implementation Method 1
a high-frequency electromagnetic field is generated and the target's influence on this field is determined
Implementation Method 2
a signal resonant circuit and a reference resonant circuit
Implementation Method 3
the change in the field can depend on various factors, such as the position of the target in the detection area, the electrical and magnetic material properties of the target and the mass of the target
Implementation Method 4
the oscillation characteristics of resonant circuits and the electrical properties of the components used change. Especially at long switching distances, the change in the useful signal when the target approaches can be on the order of magnitude of the effects caused by temperature changes
Data Source
Figure 1A~1B
Figure 2~5
Figure 6A~6B
AI summary
The present invention relates to an inductive proximity switch (100) comprising a signal resonant circuit and a reference resonant circuit; a multiplexer circuit (106) for alternately activating the signal resonant circuit or the reference resonant circuit; a driver circuit (108) with an oscillator for operating the activated signal resonant circuit or reference resonant circuit at an oscillator frequency; a detection module (112) for detecting a vibration parameter of the activated signal resonant circuit or reference resonant circuit; and an evaluation module (118) configured to determine a differential signal based on the vibration parameter for the activated signal resonant circuit and the vibration parameter for the activated reference resonant circuit, and to generate a control signal depending on the differential signal.The signal resonant circuit is designed such that the vibration parameter depends on the position of a target (128) in a detection area (126); and the reference resonant circuit is designed such that the vibration parameter is essentially independent of the position of the target (128) in the detection area (126).