Light Barrier Synchronization via Signal Integration

Solution Overview

Problem

Existing light barrier synchronization methods are susceptible to interference, leading to false detections and undesired negative switching signals, especially when faced with high-frequency interference signals.

Innovation Solution

A method where received signals are integrated in successive windows to determine integration values, which are then compared to an expected sequence of transmitted light pulses, allowing for robust and simple synchronization by generating positive or negative switching signals based on correlation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If simple synchronization methods (threshold evaluation) are used, then device complexity is reduced, but susceptibility to interference increases leading to false detections

Engineering Contradiction:

Improvesynchronization method complexityVSAvoidsusceptibility to interference

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies preliminary action by integrating the received signal over a predetermined time window before making the synchronization decision. This integration step is performed in advance of the threshold comparison, allowing the system to accumulate signal energy and suppress interference before the actual detection occurs. The integration window is set to match the expected pulse duration, ensuring that only signals with the correct temporal characteristics are detected.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter of signal evaluation from direct threshold comparison to integrated threshold comparison. By transforming the received signal through temporal integration, the system changes the amplitude distribution and suppresses high-frequency interference components. This parameter transformation allows simple threshold-based detection to become robust against interference that would otherwise cause false detections.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If time window methods are used, then device complexity is reduced, but synchronization accuracy deteriorates when interference occurs at the beginning of the time window

Engineering Contradiction:

Improvesynchronization method complexityVSAvoidsynchronization accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent extracts the temporal characteristics of the expected light pulse by defining a specific integration window that matches the pulse duration. This extraction of the temporal profile allows the system to isolate and evaluate only the relevant signal portion, rejecting interference that occurs outside this window. The integration window is precisely timed to capture the expected pulse while excluding premature interference.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If complex pulse shape analysis methods are used, then susceptibility to interference is reduced, but device complexity increases

Engineering Contradiction:

Improvesusceptibility to interferenceVSAvoidsynchronization method complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by integrating the received signal over a predetermined time window before making the synchronization decision. This integration step is performed in advance of the threshold comparison, allowing the system to accumulate signal energy and suppress interference before the actual detection occurs. The integration window is set to match the expected pulse duration, ensuring that only signals with the correct temporal characteristics are detected.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter of signal evaluation from direct threshold comparison to integrated threshold comparison. By transforming the received signal through temporal integration, the system changes the amplitude distribution and suppresses high-frequency interference components. This parameter transformation allows simple threshold-based detection to become robust against interference that would otherwise cause false detections.

Inventive Principle:

Principle #35Parameter changes

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 reduces susceptibility to interference, ensuring accurate synchronization and reliable detection of real light pulses, even in the presence of high-frequency interference, thereby maintaining system stability and accuracy.

Implementation Method 1

An assigned receiver receives these transmitted light pulses and generates corresponding electrical received signals

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP1843175B1Synchronisation method for a light barrier and corresponding light barrier

Publication Date: 2010.01.20 SICK AG

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Figure 2(a)~2(f)
Figure 3(a)~4(b)

AI summary

The method involves integrating received signals in integration windows to determine integration valves such that the determined integration values are compared with an expected sequence of transmitted light pulses. A positive or negative switching signal is produced depending on a result of the comparison. The integration values are discretized before comparison with the sequence of transmitted light pulses. An independent claim is also included for a light barrier for executing a method for synchronizing a receiver.