Inductive Proximity Switch Temperature Compensation for Stable Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing inductive proximity switches suffer from aging issues and temperature-induced drift and hysteresis, leading to unreliable detection characteristics.
Innovation Solution
A proximity switch with a controllable oscillation amplifier and temperature sensor, coupled with a microprocessor and storage medium, allows for open-loop and closed-loop temperature compensation, using compensation data to adjust the oscillation behavior via negative current feedback and amplifier stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wound coils are used in the oscillator, then the proximity switch can be manufactured, but the switching distance drifts over time due to aging
Solution Approach 1:
The patent uses temperature compensation circuits that adjust electrical parameters (resistance, capacitance) based on detected temperature values to compensate for aging effects and maintain stable switching distance over time
Solution Approach 2:
The patent implements feedback mechanisms where temperature sensors continuously monitor the oscillator temperature and feed this information back to adjustment circuits that modify coil parameters to compensate for aging drift
2Reliability
If temperature compensation circuits are added, then temperature-induced drift is compensated, but the device complexity increases
Solution Approach 1:
The patent adjusts electrical parameters of existing circuit components (resistors, capacitors) based on temperature to achieve compensation without adding complex structural elements
Solution Approach 2:
The patent designs temperature compensation circuits that serve multiple functions: temperature sensing, signal processing, and parameter adjustment, thereby reducing overall device complexity
3Reliability
If controllable networks with transconductance amplifiers are used, then temperature-induced variations are compensated, but the structural complexity becomes very high
Solution Approach 1:
The patent uses simple parameter adjustments in existing amplifier circuits rather than complex controllable networks, achieving temperature compensation through resistor or capacitor value changes based on temperature
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
Compensates for temperature-induced variations, enhancing detection reliability and stability across varying temperature conditions.
Implementation Method 1
at least one temperature sensor provided for detecting the temperature of an element of the proximity switch, such as a surface temperature, and/or the ambient temperature, in particular for detecting the temperature of the oscillator amplifier and/or of a coil
Implementation Method 2
an oscillator, which generates an alternating magnetic field, in particular in a self-energized manner, and changes its oscillation state as a result of a target entering the detection range
Implementation Method 3
Inductive proximity switches are known in the state of the art, thus for example DE 44 29 314 B4 describes such a proximity switch in which an alternating magnetic field is generated in a coil, with the result that a metal object entering said field influences the oscillation state
Implementation Method 4
at least one oscillation amplifier, wherein the oscillation amplifier is formed so as to be controllable in an open-loop and closed-loop manner and has at least one amplifier stage
Data Source
AI summary
A proximity switch is disclosed. In an embodiment, the proximity switch has a defined detection range and includes an oscillator, an oscillator amplifier, a temperature sensor, a microprocessor and a storage medium. The oscillator generates an alternating magnetic field and changes its oscillation state as a result of a target entering the detection range. The oscillator amplifier is configured to be controllable in an open-loop and closed-loop manner and has at least one amplifier stage. In this embodiment, the at least one amplifier stage has a controllable temperature compensation circuit which is configured to influence the oscillation behaviour of the oscillator based on compensation values received as control data from the microprocessor and/or from the storage medium, depending on a temperature detected by the temperature sensor. The disclosed embodiments also encompass a method for operating a proximity switch with temperature compensation.