Elevator Door Light Grid Using Intensity Thresholds for Reversal Detection
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Solution Overview
Problem
Existing light grids for sliding doors, particularly in elevators, lack precision in detecting door movements and conditions such as reversals and dirtiness, and do not allow for detailed evaluation of door states.
Innovation Solution
A light grid system with transmitter and receiver elements that emit and receive radiation, a control device evaluating intensity values to distinguish between high, medium, and low intensity ranges, and detect transitions between these ranges to identify door reversals and defects, with wireless signal transmission capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light grid uses simple binary detection (interrupted/not interrupted), then the device complexity is low, but the measurement precision of door movement detection is insufficient
Solution Approach 1:
The patent changes the detection parameter from binary (interrupted/not interrupted) to multi-level intensity values. The receiver element outputs intensity values that are evaluated against multiple thresholds (first threshold, second threshold) to distinguish between different door positions (fully open, partially open, fully closed). This parameter transformation enables precise door movement detection while keeping the hardware relatively simple.
2Reliability
If a light grid detects only object presence, then the device complexity is low, but the reliability of door condition monitoring is insufficient
Solution Approach 1:
The patent implements feedback by continuously monitoring radiation intensity and comparing it against predefined thresholds. The control device receives intensity values, evaluates them against first and second thresholds, and generates appropriate output signals based on the door's actual state. This feedback mechanism reliably detects door conditions including reversals and abnormalities by continuously adjusting detection based on real-time intensity measurements.
Solution Approach 2:
The patent segments the detection range into multiple intensity value ranges (first range above first threshold, second range between first and second thresholds, third range below second threshold). Each range corresponds to specific door positions or conditions. This segmentation allows the system to reliably distinguish between different door states (fully open, partially open, fully closed, reversal) using a single receiver element, improving reliability without requiring multiple sensors.
3Measurement precision
If a light grid uses multiple receiver elements to detect intensity variations, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
Instead of using multiple receiver elements, the patent changes the parameter detection approach by having a single receiver element output multiple intensity values that are then processed through threshold evaluation. The control device distinguishes between different intensity ranges (first, second, third ranges) to determine door position. This parameter-based differentiation achieves the same measurement precision as multiple receivers would provide, but with simpler hardware architecture.
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
Enhances the detection of door reversals and defects with improved precision and allows for detailed evaluation of door conditions, facilitating easier assembly and remote signal processing.
Implementation Method 1
at least one transmitter element on a transmitter strip which emits radiation with a specific intensity
Implementation Method 2
at least one receiver element on a receiver strip which receives the radiation from an associated transmitter element
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3b
AI summary
The light grid according to the invention is a light grid for mounting on a sliding door, in particular an elevator car door, for object detection and for determining periodic door movements, comprising at least one transmitter element on a transmitter strip which emits radiation with a specific intensity, at least one receiver element on a receiver strip which receives the radiation from an associated transmitter element, and a control device for evaluating the receiver elements for interruptions in the radiation coming from an associated transmitter element and for outputting a signal for object detection upon interruption, wherein at least one receiver element is configured to output an intensity value for the received radiation and the control device is configured to evaluate the intensity value and to distinguish between separate high, medium and low intensity value ranges with high,to distinguish between medium and low intensity values, to detect a transition phase with at least one change from the low to the medium to the low intensity value range, and to output a signal when a transition phase is detected.