Interlocked Light Curtain Access Protection Against Unauthorized Restart
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Solution Overview
Problem
Existing access protection systems face challenges in ensuring safety during special operating modes, particularly during maintenance or repair, where unauthorized restarts can occur due to the inability to prevent third-party intervention while a person is still in the hazardous area.
Innovation Solution
An access protection system incorporating an interlocking device with a movable blocking element that can be locked in place to prevent light pulses from being received by the optical receiver, ensuring that the system cannot be restarted unless the blocking element is manually released, providing additional mechanical safety against unauthorized restarts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a restart button is provided to enable system restart after leaving the protective field, then the system can be restarted safely, but unauthorized restarts may occur when persons are still in the hazardous area
Solution Approach 1:
The patent introduces an intermediary mechanism (the blocking element that physically obstructs access to the restart button) between the operator and the restart function. This mediator prevents unauthorized restarts by requiring the operator to first clear the hazardous area and remove the blocking element before the restart button becomes accessible, thereby resolving the contradiction between enabling safe restarts and preventing unauthorized restarts
2Reliability
If additional detection means such as light grids or scanners are added to detect persons in the hazardous area, then detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the existing light curtain serve multiple functions: it not only detects persons entering the hazardous area (original function) but also, through its associated blocking element mechanism, prevents unauthorized restarts (new function). By making the detection system multi-functional, the patent improves reliability without adding separate detection devices, thus avoiding increased complexity
3Reliability
If separate electro-sensitive protective equipment like light grids or scanners are added, then safety detection is improved, but manufacturing cost and installation effort increase
Solution Approach 1:
The patent combines the safety detection function and the restart prevention function into a single integrated system. The blocking element is coupled with the light curtain's control circuitry, so that when the light curtain detects a person, it triggers the blocking mechanism. This merging eliminates the need for separate detection equipment and reduces both manufacturing and installation complexity
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 enhances safety by preventing unauthorized system restarts during special operating modes, reducing the risk of accidents and ensuring that the system remains in a safe state until the area is cleared, while being cost-effective and easy to integrate into existing systems.
Implementation Method 1
The optical transmitter is configured to send a light pulse to the optical receiver
Data Source
AI summary
An access protection system for safeguarding an access point to a machine or installation includes a sensor device and an interlocking device. The sensor device includes an optical transmitter and receiver. The interlocking device includes a base body and a blocking element. The optical transmitter is configured to transmit a light pulse to the optical receiver. The sensor device is configured to generate a sensor signal based on reception of the light pulse. The sensor signal is used to control the machine or installation. The blocking element is movable relative to the base body from a release position into a blocking position. The blocking element is configured to be located, while in the blocking position, in a beam path of the light pulse between the optical transmitter and receiver to block the reception of the light pulse. The interlocking device is lockable in the blocking position by a securing element.