Light Curtain Device Interference Mitigation via Channel Segmentation

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Solution Overview

Problem

Light curtain devices experience 'inter-device' interference issues, where radiation from one surveillance channel can illuminate and interfere with detectors of another, leading to failed object detection if an object interrupts a channel.

Innovation Solution

A control unit is implemented to perform a collision detection procedure, identifying colliding and collision-free channels by activating each surveillance channel individually, determining affected detectors and emitters, and assigning collision-free channels to create optimized detection steps that minimize interference, ensuring simultaneous activation of only collision-free channels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple surveillance channels are activated simultaneously to improve detection coverage, then the detection capability is enhanced, but inter-device interference occurs causing detection failures

Engineering Contradiction:
Improveobject detection accuracyVSAvoidinter-device interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the surveillance channels into different groups based on their interference characteristics. By analyzing which channels interfere with each other and creating segmented groups of compatible channels, the system can activate multiple non-interfering channels simultaneously while avoiding activation of channels that would cause interference, thus maintaining detection accuracy while maximizing coverage.

Inventive Principle:
Principle #1Segmentation

2Area of stationary object

If all surveillance channels are activated at once to maximize detection coverage, then the monitoring area is improved, but false triggers increase due to interference

Engineering Contradiction:
Improvemonitoring coverage areaVSAvoidfalse detection signals
Core Design Contradiction:
Area of stationary objectVSLoss of information

Solution Approach 1:

The patent performs preliminary analysis to identify which surveillance channels are compatible and will not interfere with each other before activating them. By pre-determining the compatibility relationships between channels and organizing them into valid activation groups, the system can safely activate the maximum number of non-interfering channels simultaneously, maximizing coverage while preventing false triggers from interference.

Inventive Principle:
Principle #10Preliminary action

3Object-affected harmful factors

If channels are activated sequentially to avoid interference, then inter-device interference is eliminated, but detection response time increases

Engineering Contradiction:
Improveinter-device interferenceVSAvoiddetection response time
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent implements periodic activation of different groups of surveillance channels in a cyclic manner. Instead of activating channels one at a time sequentially, the system organizes channels into multiple compatible groups and periodically switches between these groups, allowing maximum parallel operation within each group while eliminating inter-group interference. This periodic group activation significantly reduces detection response time compared to strict sequential activation.

Inventive Principle:
Principle #19Periodic action

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 solution effectively mitigates inter-device interference, ensuring accurate object detection by activating only collision-free channels, thereby preventing false triggers and maintaining the protection level of the light curtain device without introducing significant time delays.

Implementation Method 1

a plurality of radiation emitters (E1-E5) and a plurality of detectors (D1-D5)... each of the emitters (E1-E5) forms a surveillance channel (SC1-SC5) together with an individually assigned detector (D1-D5)

Methodology Applied
Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Implementation Method 2

a plurality of detectors (D1-D5)... evaluating the detection signals of the detectors (D1-D5)... determining whether an object interrupts a surveillance channel (SC1-SC5)

Methodology Applied
Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentEP4141494A1Light curtain device and method
Publication Date: 2023.03.01 PEPPERL & FUCHS SE
  • EP4141494A1 patent drawingFigure 1
  • EP4141494A1 patent drawingFigure 2
  • EP4141494A1 patent drawingFigure 3

AI summary

An exemplary embodiment of the present invention relates to a light curtain device (LC). A control unit is configured to carry out a collision detection procedure (110) and a definition procedure (120) for defining at least one detection step with respect to a selected surveillance channel.