Safety Sensor Muting Control for Hazardous Area Availability
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Solution Overview
Problem
Existing monitoring devices for danger zones, such as light curtains, often unnecessarily restrict system availability by triggering safety functions when permissible objects are detected, leading to unnecessary downtimes and reduced safety zone monitoring efficiency.
Innovation Solution
A monitoring device with a bridging device that controls the muting function based on object detection signals and switching signals, activating bridging only when both signals change to 'on' within a monitored time interval, and maintaining bridging until both signals return to 'off', with error control mechanisms to ensure safe operation and prevent uncontrolled muting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light curtain triggers the safety function when an object is detected in the protective field, then the safety of the system is improved, but the availability of the system deteriorates due to unnecessary shutdowns when permissible objects are detected
Solution Approach 1:
The patent introduces a bridging device as an intermediary component that receives both the switching signal from the control unit and the object detection signal from the light curtain. This mediator evaluates the temporal relationship between these signals and controls the muting function accordingly, allowing permissible objects to pass without triggering safety shutdowns while maintaining protection against unauthorized access
Solution Approach 2:
The control unit generates a switching signal in advance when a permissible object approaches the light curtain, before the object actually enters the protective field. This preliminary action allows the bridging device to anticipate the object's passage and activate the muting function appropriately, preventing unnecessary safety triggers while maintaining system availability
2Productivity
If the muting function is activated to allow permissible objects to pass through the light curtain, then the availability of the system is improved, but the safety monitoring capability deteriorates during the muting period
Solution Approach 1:
The bridging device continuously monitors both the switching signal from the control unit and the object detection signal from the light curtain, evaluating their temporal relationship in real-time. This feedback mechanism ensures that the muting function is activated only when the switching signal precedes the object detection signal within the monitored time interval, maintaining safety while allowing permissible objects to pass
Solution Approach 2:
The muting function is dynamically controlled based on the temporal relationship between the switching signal and object detection signal. The bridging device adjusts the muting state in real-time, activating it only when the switching signal is generated within the monitored time interval before the object detection signal, and deactivating it when the temporal relationship is not met, thus adapting safety monitoring to the actual operational context
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 enhances safety zone monitoring by preventing unnecessary system shutdowns while ensuring safety, thereby increasing system availability without compromising danger area protection.
Implementation Method 1
a light curtain, which typically has a series arrangement of light beam emitting transmitters in a first housing and a series arrangement of light beam receiving receivers
Data Source
Figure 1
Figure 2
Figure 3a~3c
AI summary
The invention relates to a monitoring device (1) for monitoring a hazardous area at a system (2), comprising a safety sensor that monitors a protective field. The safety sensor (6) generates a binary object detection signal, which is in the "on" state when no object is present in the protective field and in the "off" state when an object is present. The object detection signal in the "on" state triggers a safety function for the system (2). Furthermore, a bridging unit is provided, to which the object detection signal and a binary switching signal with "on" and "off" states are supplied.The bridging device activates a bridging cycle, during which the safety function of the safety sensor (6) is bypassed, only if, within a time interval monitored by the bridging unit, the switching signal and the object detection signal both switch to the "on" state. The bridging is maintained until both the switching signal and the object detection signal have switched to the "off" state, the time difference between these signal changes being arbitrary and not monitored by the bridging device.