Light Curtain Amplifier Testing for Reliable Object Detection

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Solution Overview

Problem

Existing light curtains suffer from malfunctions in amplifiers leading to incorrect object detections due to unreliable signal amplification, which can compromise safety in security applications.

Innovation Solution

A light curtain with a test device to detect amplifier malfunctions, utilizing an addressing unit to trigger specific test processes and generate error messages or stop the system if faults are detected, ensuring reliable object detection by testing amplifier properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If amplifiers are used to amplify received signals to increase detection sensitivity, then detection sensitivity is improved, but amplifier malfunctions can cause incorrect detections reducing reliability

Engineering Contradiction:
Improvedetection sensitivityVSAvoiddetection reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements preliminary testing of amplifiers by injecting test signals before normal operation to detect malfunctions in advance. The test device activates amplifiers with known test signals and evaluates their responses to identify defective amplifiers before they cause incorrect object detections, thus preventing reliability issues while maintaining the sensitivity enhancement from amplification.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent establishes a feedback mechanism where test signals are injected into amplifiers and their amplified responses are evaluated and compared against expected values. This closed-loop feedback system continuously monitors amplifier performance and identifies malfunctions, allowing the system to maintain reliable operation by detecting and addressing amplifier issues that would otherwise compromise detection accuracy.

Inventive Principle:
Principle #23Feedback

2Use of energy by moving object

If individual transmitters and receivers are activated cyclically to reduce power consumption, then energy efficiency is improved, but synchronization complexity increases

Engineering Contradiction:
Improvepower consumptionVSAvoidsynchronization complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent employs shift registers that serve dual functions: they control the cyclic activation of transmitters and receivers to reduce power consumption, and simultaneously provide synchronization through their inherent sequential timing characteristics. This multi-functionality eliminates the need for separate synchronization circuits, maintaining energy efficiency while reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces complex mechanical or hardware-based synchronization mechanisms with electronic shift register-based timing control. The shift registers generate precise timing signals through their sequential state transitions, substituting potential mechanical synchronization components with simpler electronic logic that achieves the same coordination function with reduced complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

The solution prevents false detections by identifying and addressing amplifier faults, enhancing the reliability and safety of the light curtain in security applications.

Implementation Method 1

an array of transmitters (4) emitting light beams (3), an array of receivers (6) receiving light beams (3)

Methodology Applied
Scientific EffectLight: Light

Implementation Method 2

an array of amplifiers (9) in which the received signals of the receivers (6) are amplified

Methodology Applied
Scientific EffectSignal amplification:

Data Source

PatentEP4411427B1Light curtain
Publication Date: 2025.08.20 LEUZE ELECTRONIC GMBH & CO KG
  • EP4411427B1 patent drawingFigure 1
  • EP4411427B1 patent drawingFigure 2
  • EP4411427B1 patent drawingFigure 3

AI summary

The invention relates to a light curtain (1) for detecting objects in a monitoring area, comprising an arrangement of light beams (3) emitting transmitters (4), an arrangement of light beams (3) receiving receivers (6), and an arrangement of amplifiers (9, 9a) in which the received signals from the receivers (6) are amplified. An evaluation unit (8) generates an object detection signal in the form of a binary switching signal based on the amplified received signals, the switching states of which indicate whether an object is present in the monitoring area or not. A test device is provided by means of which the amplification characteristics of the amplifiers (9, 9a) are tested.