Light Grid Distance Measurement Using Modulated Intensity
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Solution Overview
Problem
Existing light grids for object detection, such as those used in elevator doors, are costly and suffer from inaccuracies due to ambient light and mounting impreciseness, necessitating improved monitoring with reduced costs and enhanced precision.
Innovation Solution
A light grid system with qualified transmitter and receiver elements that emit different intensity levels and apply varying amplification factors, allowing for precise distance measurement and dynamic process tracking without sacrificing safety, using a control device to control and evaluate these combinations for unique distance assignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional light grids are used for object detection, then object detection function is provided, but measurement precision and reliability are reduced due to ambient light interference and mounting impreciseness
Solution Approach 1:
The transmitter elements emit light in periodic sequences with different intensity levels (e.g., high, medium, low intensity in alternating half-periods). This periodic modulation allows the receiver to distinguish between light from the transmitter and ambient light by analyzing the temporal pattern, thereby improving measurement precision and reliability
Solution Approach 2:
The system changes the intensity parameter of the transmitted light between different time periods (high intensity in one half-period, low intensity in another). By measuring the receiver signal at different intensity levels and calculating the difference, the system eliminates ambient light interference and achieves precise distance measurement
2Measurement precision
If multiple intensity levels and amplification factors are used for precise measurement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The control device dynamically switches between different intensity levels and amplification factors based on the measured distance. The system adapts its parameters in real-time: using higher intensity when objects are farther away and lower intensity when objects are closer, thereby maintaining measurement precision across different ranges while managing device complexity through adaptive control
3Measurement precision
If adaptive intensity control is implemented, then measurement precision across different distances is improved, but energy consumption increases
Solution Approach 1:
The transmitter dynamically changes its light intensity parameter based on the measured distance. When objects are detected at larger distances, higher intensity is used; when objects are closer, lower intensity is used. This adaptive parameter adjustment maintains measurement precision across different distances while minimizing unnecessary energy consumption
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
Enables precise distance measurement and dynamic process tracking with reduced complexity and cost, ensuring accurate object detection and door movement monitoring in elevators.
Implementation Method 1
a transmitter strip having one or more transmitter elements which emit radiation of a specific intensity
Implementation Method 2
a receiver strip having one or more receiver elements which receive the radiation from an assigned transmitter element
Data Source
AI summary
A light grid for determining the distance between transmitter and receiver strips, includes a transmitter strip with one or more transmitter elements which emit radiation having a specific intensity, a receiver strip with one or more receiver elements which receive the radiation from an assigned transmitter element, and a control device for controlling the transmitter elements and/or the receiver elements and for evaluating the receiver elements. At least one of the transmitter elements and/or at least one of the receiver elements are configured as qualified transmitter and receiver elements. The control device is configured to control different combinations of intensities and amplification factors of the qualified transmitter and/or receiver elements and to ascertain a distance value as a function of the sum of the resulting intensity values of the controlled combinations.