Door Edge Light Grid Encoding Distance via Signal Frequency
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Solution Overview
Problem
Existing light grids for door safety do not effectively differentiate between normal and safety cases, nor provide distance information to control devices, leading to potential collisions and inefficiencies in door operation.
Innovation Solution
A light grid system with a transmitter and receiver strip, an evaluation device to distinguish between normal and safety cases based on uninterrupted receiver elements, and a communication device that varies the frequency of a modulated signal to convey distance information, allowing for safer and more controlled door operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a light grid transmits only a simple status signal (normal/safety case) to a control device, then the control device can easily interpret the signal, but no distance information is provided for optimized door control
Solution Approach 1:
The patent modulates the frequency of the status signal to encode distance information. The evaluation device determines the distance value by measuring the frequency of the modulated signal transmitted by the communication device. This allows distance information to be conveyed through parameter variation (frequency modulation) of an existing signal type, avoiding the need for separate communication channels or complex protocols.
2Loss of information
If multiple signal cables are used to transmit status and distance information separately, then information transmission is reliable and distinct, but installation complexity and costs increase
Solution Approach 1:
The patent combines multiple information channels (status signal and distance information) into a single signal transmission. The communication device transmits both the door status (normal/safety case) and the distance value through one signal cable by using frequency modulation. This merging reduces the number of cables required while maintaining reliable information transmission through the modulated signal's frequency characteristics.
3Measurement precision
If the light grid provides detailed distance information and differentiated status signals, then door control precision is improved, but the signal processing and evaluation complexity increases
Solution Approach 1:
The evaluation device determines distance by measuring the frequency parameter of the modulated signal. This approach provides precise distance measurement through a simple frequency measurement process, avoiding the need for complex evaluation algorithms or multiple sensor readings. The frequency modulation directly encodes the distance value, making the evaluation process straightforward while maintaining high measurement precision.
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 system enhances safety by quickly reacting to potential collisions, reduces costs through single signal cable usage, and increases door control precision by encoding distance information within the signal frequency, thereby improving functional safety and door maintenance.
Implementation Method 1
a transmitter strip and a receiver strip with transmitter and receiver elements for the detection of an object in the plane of the door panel by interruption of the reception of individual receiver elements
Data Source
AI summary
Light grid for protecting the door edge of a motor-driven door against collision with an object, having a transmitter strip and a receiver strip with transmitter elements and receiver elements, for detecting an object in the plane of the door panels by interruption of the reception of individual receiver elements. An evaluation device distinguishes between normal and safety cases based on the detection of a status for the door, identifies the safety case if the number of uninterrupted receiving elements between door edge and object falls below a critical number, and identifies the normal case if the safety case is not identified. A communication device outputs a signal for the status. The evaluation device determines a distance value corresponding to the number of uninterrupted receiver elements below the door edge up to the first interrupted element, and the communication device varies the frequency as a function of the distance value.