Hazardous Area Monitoring with Zoned Muting Light Curtains
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Solution Overview
Problem
Existing devices for monitoring danger areas around machines require a large number of sensors and complex designs, leading to unnecessary machine shutdowns when non-safety-critical objects enter the zone, which restricts machine availability and increases maintenance complexity.
Innovation Solution
A device with a sensor unit that divides the protective field into two areas: a first area that can be bridged by a muting unit to prevent unnecessary shutdowns for non-safety-critical objects, and a second unbridgeable area that ensures safety-critical objects are detected, triggering a shutdown, with a movable protective device and simultaneous object presence signal monitoring for enhanced safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a light curtain with muting sensors is used to differentiate between safety-critical and non-safety-critical objects, then unnecessary shutdowns are prevented, but the device complexity and number of sensors increase significantly
Solution Approach 1:
The protective field is divided into multiple evaluation zones (first evaluation zone and second evaluation zone) with different safety requirements. The first zone allows muting for non-safety-critical objects, while the second zone requires immediate shutdown. This segmentation enables differentiated safety responses without requiring additional muting sensors throughout the entire field.
Solution Approach 2:
Different safety functions are assigned to different spatial zones within the protective field. The first evaluation zone has a relaxed safety function allowing bridging, while the second evaluation zone has a strict safety function requiring immediate shutdown. This local differentiation reduces the need for numerous sensors while maintaining appropriate safety levels in each zone.
2Measurement precision
If multiple sensors and complex control systems are deployed to monitor the danger zone, then safety detection capability is improved, but maintenance complexity and system reliability decrease
Solution Approach 1:
The monitoring system is segmented into multiple independent evaluation zones, each with its own detection and response characteristics. This segmentation allows the system to maintain high detection accuracy through zone-specific evaluation while improving overall reliability by isolating failure modes to individual zones rather than affecting the entire system.
3Reliability
If a single unbridgeable protective zone is used, then safety-critical object detection is ensured, but unnecessary shutdowns occur when non-safety-critical objects pass through
Solution Approach 1:
The protective field is segmented into a first evaluation zone where non-safety-critical objects can be muted, and a second evaluation zone that remains unbridgeable for safety-critical detection. This segmentation allows the system to maintain high machine availability in the first zone while ensuring safety reliability in the second zone.
Solution Approach 2:
Different safety functions are applied locally to different zones: the first evaluation zone allows bridging for non-critical objects to maintain productivity, while the second evaluation zone enforces strict shutdown requirements to ensure safety. This local quality differentiation resolves the contradiction between availability and safety.
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 reliably detects safety-critical interventions while minimizing unnecessary machine downtime and maintaining high availability, ensuring safe operation by differentiating between non-safety-critical and safety-critical objects and preventing uncontrolled interventions.
Implementation Method 1
a sensor unit with at least one radiation-emitting transmitter and a radiation-receiving receiver for monitoring a protective field and for detecting an object
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a device (1) for monitoring a hazardous area (2) of a machine (3) or system, comprising a sensor unit (4) with at least one beam-emitting transmitter (6) and a beam-receiving receiver (7) for monitoring a protective field (8) and for detecting an object (9) in at least a first protective area (10) of the protective field (8), and with an evaluation unit (11) in which, upon detection of an object (9) in the protective field (8), a shutdown command for the machine (3) or system is generated as a safety function. The protective field (8) has a second protective area (14) which is monitored by associated beams (15) or additional beams from the transmitter (6). The intrusion of a safety-critical object (12) into the second protective area (14) is detected by the sensor unit (4) and the evaluation unit (11), and a shutdown command for the machine (3) or system is generated.A bridging unit (16) allows the safety function of the sensor unit (4) with respect to the first protection zone (10) to be bypassed if a non-safety-critical object (9) enters the first protection zone (10). The safety function in the second protection zone (14) cannot be bypassed.