Light Curtain Muting Zones for Reliable Conveyor Safety
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Solution Overview
Problem
Existing security arrangements with light curtains face errors due to incorrect placement of muting sensors, leading to unnecessary downtime or unsafe conditions, as they struggle to distinguish between non-safety-critical and safety-critical objects accurately.
Innovation Solution
The monitoring area is divided into protection and muting control areas, with muting sensors activating only in the muting control area to prevent false triggers, ensuring non-safety-critical objects can pass without triggering safety output signals and maintaining safety for critical objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If muting sensors are mounted at a predetermined height above the conveyor belt, then non-safety-critical objects can be detected for muting activation, but small non-safety-critical objects may not be detected leading to unnecessary shutdown commands
Solution Approach 1:
The monitored area is divided into a protection area (where safety-critical objects are detected) and a muting control area (where non-safety-critical objects are detected). This spatial segmentation allows the system to differentiate between object types based on detection location, preventing unnecessary shutdowns while maintaining safety.
2Ease of operation
If muting sensors are mounted too low above the conveyor belt, then even minor unevenness can trigger the muting sensors, but this causes improper muting allowing safety-critical objects to pass without generating safety output signals
Solution Approach 1:
The monitored area is divided into a protection area (where safety-critical objects are detected) and a muting control area (where non-safety-critical objects are detected). This spatial segmentation allows the system to differentiate between object types based on detection location, preventing unnecessary shutdowns while maintaining safety.
Solution Approach 2:
The muting control area acts as an intermediary zone between the conveyor belt and the protection area. Objects detected in this intermediate zone trigger muting, while objects detected in the protection area trigger safety shutdowns. This intermediary detection zone prevents false triggering from conveyor unevenness.
3Productivity
If the light curtain is muted for a specified period of time after detecting non-safety-critical objects, then these objects can pass without generating shutdown commands, but this may allow safety-critical objects to pass during the muting period
Solution Approach 1:
The monitored area is divided into a protection area (where safety-critical objects are detected) and a muting control area (where non-safety-critical objects are detected). This spatial segmentation allows the system to differentiate between object types based on detection location, preventing unnecessary shutdowns while maintaining safety.
Solution Approach 2:
The system continuously monitors both the muting control area and protection area. When an object is detected in the protection area during a muting period, the system provides feedback to immediately terminate muting and activate the safety shutdown function, ensuring safety-critical objects are never allowed to pass undetected.
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 enhances the reliability of the security arrangement by preventing unnecessary downtime and ensuring safe conditions by accurately differentiating between object types and preventing uncontrolled dangerous situations.
Implementation Method 1
a light curtain for detecting objects in a monitored area... comprising an arrangement of beam axes, each formed by a transmitter (4) emitting light beams (3) and at least one associated receiver (6)
Implementation Method 2
at least one muting sensor (11, 12) which can detect objects conveyed on the conveyor (9)
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3~4
AI summary
The invention relates to a safety arrangement (1) with a light curtain (2) for detecting objects in a monitoring area (8) with an arrangement of beam axes, each formed by a light beam emitting transmitter (4) (3) and at least one associated receiver (6). The monitoring area (8) is monitored by the beam axes or by an area scanner (20) in which light beams (21) emitted by a transmitter (22) sweep over the monitoring area (8). The monitoring area (8) is divided into at least one protection area (13) and at least one muting control area (14), wherein muting functions can be controlled depending on object detection in the muting control area (14). A safety output signal is generated upon object detection in the protection area (13) only if muting is not activated.