Safety Light Grid With Integrated Control Logic

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Solution Overview

Problem

Existing safety light grids used in hazardous areas are prone to false shutdowns due to interference from debris like sawdust, leading to unnecessary machine downtimes and reduced robustness against faults, requiring external control logic for evaluation.

Innovation Solution

A safety system comprising a primary and secondary danger area monitored by interconnected safety sensors with integrated control and evaluation units, allowing for internal evaluation and object detection signal transmission without external logic, ensuring the secondary area remains inactive until an object is detected in the primary area, thus preventing false shutdowns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple safety sensors (primary and secondary) are deployed to monitor different danger areas, then safety coverage is improved, but false shutdowns occur due to debris detection in the secondary area

Engineering Contradiction:
Improvesafety coverageVSAvoidmachine availability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system performs preliminary evaluation in the primary danger area before activating monitoring in the secondary danger area. The control unit only enables the secondary safety sensor when an object is first detected in the primary area, preventing premature or false detections in the secondary area from causing shutdowns

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The monitoring system dynamically adjusts its sensitivity and active monitoring zones based on the detection state. The secondary safety sensor transitions from an inactive state to an active monitoring state only when triggered by a primary area detection, allowing the system to adapt its monitoring intensity to actual operational needs

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If external control logic is used to evaluate safety sensor signals, then evaluation flexibility is improved, but system complexity increases

Engineering Contradiction:
Improveevaluation flexibilityVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The control unit integrates multiple evaluation functions within a single integrated component. The control unit combines signal reception from multiple safety sensors, preliminary evaluation of primary area detections, conditional activation of secondary area monitoring, and shutdown control logic into one unified device, eliminating the need for separate external control systems

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The control unit serves multiple functions: it receives signals from both primary and secondary safety sensors, evaluates detection conditions, controls the monitoring state transitions, and manages shutdown operations. This multi-functional design consolidates what would traditionally require multiple separate components

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

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

Enhances the robustness and availability of the safety system by eliminating the need for external control logic and reducing false shutdowns from debris, ensuring the system remains active unless an object is detected in both primary and secondary danger areas.

Implementation Method 1

light transmitters and light receivers face each other in pairs and form the protective field of the safety light grid between them. If at least one light beam is interrupted, which is detected by a light receiver, the safety switching signal is output.

Methodology Applied
Scientific EffectOptical detection: Photoelectric Effect

Data Source

PatentEP3133331B1Safety system and method for monitoring
Publication Date: 2018.04.18 SICK AG
  • EP3133331B1 patent drawingFigure 1
  • EP3133331B1 patent drawingFigure 2
  • EP3133331B1 patent drawingFigure 3

AI summary

Method and safety system with at least one first safety sensor (2) for monitoring a primary hazard area (3), wherein the first safety sensor (2) has a first control and evaluation unit (4), and with at least one second safety sensor (5) for monitoring a secondary hazard area (6), wherein the second safety sensor (5) has a second control and evaluation unit (7), wherein the secondary hazard area (6) is only accessible through the primary hazard area (3), wherein the first safety sensor (2) and the second safety sensor (5) are electrically or electronically connected, wherein the first safety sensor (2) or the second safety sensor (5) is configured to output at least one object detection signal, wherein an evaluation of the first safety sensor (2) and the second safety sensor (5) is carried out by the first control and evaluation unit (4) and/or by the second control and evaluation unit (7).