Railway LED Light Signal with Series-Strand Segmentation
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Solution Overview
Problem
Conventional light signal transmitters for level crossings face issues with uneven light distribution due to spatially offset filaments, short service life of incandescent lamps, and difficulty in monitoring individual LED failures in high-power LED arrays, leading to depth phantom reflections and unreliable fault detection.
Innovation Solution
An LED arrangement using a few high-power LEDs per line, connected in series and arranged to maintain even light distribution, with voltage monitoring for reliable fault detection and automatic switching between strands, allowing for seamless transition without noticeable changes in light appearance and extended service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a large number of LEDs are used per light signal to achieve required luminance, then the light distribution becomes uneven and depth reflex phantoms occur, but if only a few high-power LEDs are used, then individual LED failures cannot be reliably monitored
Solution Approach 1:
The light signal is divided into multiple independent strands, each consisting of a small number of high-power LEDs. This segmentation allows that if one LED fails in a strand, the other LEDs in the same strand can still contribute to the light signal, and the failure can be monitored through voltage changes in the series circuit. The segmentation principle resolves the contradiction by distributing the monitoring task across multiple smaller units rather than relying on a single large array where individual failures are lost in the noise.
Solution Approach 2:
The patent implements feedback through voltage monitoring of the LED strands. Since LEDs are connected in series, a failure of an individual LED changes the voltage distribution across the strand, which can be detected by the control unit. This feedback mechanism allows reliable monitoring of individual LED failures even in arrays of high-power LEDs, resolving the contradiction between using few LEDs for even light distribution and maintaining fault detection capability.
2Reliability
If conventional two-filament incandescent lamps are used, then fault monitoring is reliable, but the service life is short and light distribution is uneven
Solution Approach 1:
The patent replaces the mechanical/incandescent filament system with an LED electroluminescence system. This substitution eliminates the short service life problem of incandescent lamps while maintaining fault monitoring capability through voltage sensing in the series-connected LED strands. The replacement of the physical filament mechanism with semiconductor diodes resolves the contradiction between reliable fault monitoring and long service life.
3Reliability
If spatially offset filaments are used in incandescent lamps, then backup functionality is provided, but light distribution becomes uneven
Solution Approach 1:
The patent merges multiple LED strands into a single integrated light signal unit where the LEDs are arranged to produce even light distribution. The backup functionality is maintained through the series connection of strands, where a failure in one strand can be detected and the system can switch to alternative strands. This merging approach eliminates the need for spatially offset filaments while preserving backup capability through electrical series connection rather than spatial separation.
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 ensures reliable detection of individual LED failures, avoids depth phantom reflections, and maintains consistent light distribution, enhancing the service life and operational reliability of LED light signal transmitters while integrating with standard control modules.
Implementation Method 1
An LED arrangement (100) for light signal transmitters for level crossings
Implementation Method 2
with voltage monitoring for reliable fault detection
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The arrangement has two strands of high performance-LEDs (32, 34) connected in series, where the LEDs are arranged on a common circuit board such that the LEDs of one strand produce same light distribution as the LEDs of the other strand. The strands separated from each other are supplied with current to activate the LEDs in the respective strands. A monitoring unit monitors current flowing in the strands and voltage flowing to the strands. A control unit is provided for automatic change over to another strand during failure of the working strand or the LED of the working strand. An independent claim is also included for a method for operating an LED arrangement.