Inductive Proximity Sensor Synchronization Against Coil Interference
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Solution Overview
Problem
Inductive proximity sensors experience interference due to magnetic coupling when operated in close proximity, leading to unreliable synchronization and reduced measurement rates.
Innovation Solution
A synchronization mechanism using a synchronization line to coordinate the operation of multiple inductive proximity sensors, ensuring that pulse evaluations are synchronized to avoid interference by delaying the start of pulse evaluation processes when adjacent sensors are active.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple inductive proximity sensors are operated in close proximity using pulse evaluation processes, then measurement redundancy and detection capability are improved, but magnetic coupling between sensor coils causes interference voltages that worsen measurement reliability
Solution Approach 1:
The patent applies periodic action by using cyclic current pulses with specific timing for excitation and evaluation. The sensor operates in periodic cycles where a current pulse is applied to the coil, followed by an evaluation phase where the voltage response is measured. This periodic operation allows multiple sensors to share the detection space by coordinating their active and evaluation phases, reducing mutual interference while maintaining detection capability.
Solution Approach 2:
The patent implements preliminary action through a synchronization mechanism that determines whether another sensor is currently active before starting a pulse evaluation process. The control unit checks the state of adjacent sensors in advance and delays the start of the evaluation phase if interference is detected, ensuring that measurements are taken only when no other sensor is actively generating magnetic fields.
2Ease of operation
If the phase position of cyclic current pulses is fixed, then sensor operation is simplified, but clock source scattering causes phase drift that worsens interference between adjacent sensors
Solution Approach 1:
The patent employs feedback through a synchronization mechanism where sensors monitor the activity state of adjacent sensors and adjust their pulse evaluation timing accordingly. The control unit receives feedback about the active state of other sensors and modifies the start timing of its evaluation phase to avoid interference, creating a self-regulating system that maintains synchronization despite clock variations.
Solution Approach 2:
The patent applies dynamics by making the pulse evaluation start time adjustable rather than fixed. The control unit can dynamically delay the start of the evaluation phase based on the detected activity state of adjacent sensors, allowing the system to adapt its timing to avoid interference while maintaining coordinated operation across multiple sensors.
3Reliability
If self-synchronization is used to avoid interference, then measurement reliability is improved, but coupling must remain above minimum level which limits sensor placement flexibility
Solution Approach 1:
The patent uses an intermediary synchronization mechanism that mediates between multiple sensors through a shared communication channel. Instead of relying solely on magnetic field coupling for synchronization, the sensors use a dedicated synchronization signal to coordinate their operation, allowing them to maintain reliable synchronization even when placed closer together than traditional methods would allow.
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
Ensures reliable operation and maintains high measurement rates by preventing interference between adjacent sensors, allowing for synchronized and efficient detection of objects.
Implementation Method 1
The voltage response varies due to the induction of eddy currents in the object to be detected
Implementation Method 2
The voltage response varies due to the induction of eddy currents in the object to be detected
Implementation Method 3
If the sensor coils of the proximity sensors are arranged to be close to each other, there is a magnetic coupling with a non-negligible coupling factor between the sensor coils. Thus, a time-varying magnetic field caused by one of the sensor coils may induce interference voltages in the sensor coil of another one of the proximity sensors
Data Source
AI summary
The invention relates to an inductive proximity sensor, comprising:a sensor coil;a pulse evaluation circuit which is configured to provide an excitation pulse for the sensor coil and to obtain a resulting voltage response;a control unit which is configured toto control the pulse evaluation circuit according to a pulse evaluation process such that the sensor coil is excited by an excitation pulse of a predetermined duration of time;to detect at least a first measurement voltage at a specific first point in time after providing the excitation pulse, andto provide an indication regarding the presence or absence of an object to be detected in a detection area around a sensor coil,wherein a synchronization unit is provided in order to receive a synchronization signal which indicates if or when a pulse evaluation process is active in an adjacent proximity sensor, and in that the control unit is configured to start the pulse evaluation process in dependence on the synchronization signal.