Transit Vehicle LED Lighting Control Network Architecture
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Solution Overview
Problem
Conventional lighting systems in transit vehicles, such as fluorescent lighting, have limitations including short lifetime, high current draw, electromagnetic compatibility issues, arcing problems, and lack of flexibility in control, which are not effectively addressed by previous attempts to incorporate LED lighting.
Innovation Solution
An LED-based lighting system with a network architecture that includes a master node, slave nodes, and a digital communications bus integrated with the power supply cable, allowing for temperature and age-based current adjustment, automatic dimming, and reduced LED usage in emergency modes, while simplifying wiring and providing flexible control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluorescent lighting is used in transit vehicles, then illumination is provided, but the system suffers from short lifetime, high current draw, electromagnetic compatibility issues, and arcing problems
Solution Approach 1:
The patent transitions from fluorescent lighting technology to LED lighting technology, fundamentally changing the operating parameters including current draw, lifetime, and electromagnetic emissions. LEDs operate at lower currents, provide longer lifetime, and eliminate the electromagnetic compatibility issues and arcing problems associated with fluorescent systems.
Solution Approach 2:
The patent replaces the fluorescent lighting system with an LED-based system, substituting one technological approach with another that eliminates the harmful effects. The LED system uses different physical principles (electroluminescence in solid-state devices) compared to fluorescent lamps (gas discharge and phosphor excitation), thereby eliminating electromagnetic interference and arcing.
2Loss of energy
If fluorescent lighting is dimmed, then power consumption is reduced, but the lamp filaments may go out or suffer severe degradation
Solution Approach 1:
The patent changes the lighting technology from fluorescent to LED, which allows for smooth dimming operation without the filament degradation issues. LEDs can be dimmed by pulse-width modulation or current reduction without risking filament failure, as they lack the fragile filament structure of traditional lamps.
Solution Approach 2:
This principle is not directly applicable here. The patent actually aims to avoid disposable/short-lived components by using LEDs with extended lifetime capability that can withstand dimming operations.
3Reliability
If fluorescent lighting is wired in point-to-point fashion, then each light receives power, but a substantial amount of wiring is required
Solution Approach 1:
The patent combines multiple wiring functions into a single communication bus that serves both power distribution and control/signaling purposes. The LED lighting system uses a daisy-chain or daisy-wire topology where a single cable carries both power and digital communication signals, eliminating the need for separate point-to-point wiring for each fixture.
Solution Approach 2:
The communication bus serves multiple functions: it provides power to the LED fixtures, carries control signals for dimming and scheduling, enables diagnostic communication, and allows for system configuration. This multi-functional approach replaces the traditional single-purpose power wiring with a versatile digital bus.
4Illumination intensity
If fluorescent lighting is used, then illumination is provided, but the system lacks flexibility in control and is difficult to dim
Solution Approach 1:
The patent implements a digital communication system that allows bidirectional communication between the control system and LED fixtures. This enables real-time monitoring of fixture status, temperature, and operational parameters, allowing for adaptive control and dimming based on actual system conditions rather than just open-loop control.
Solution Approach 2:
The LED lighting system enables dynamic control of illumination intensity through digital dimming capabilities. The system can adjust light output levels smoothly and rapidly in response to changing conditions, schedules, or user preferences, providing far greater adaptability than fluorescent systems which have limited dimming ranges and response times.
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 LED-based lighting system offers improved lifetime, reduced power consumption, enhanced control capabilities, and reduced wiring needs, addressing the limitations of traditional transit vehicle lighting while providing efficient and flexible illumination.
Implementation Method 1
a plurality of LEDs for illuminating an area of a transit vehicle
Data Source
AI summary
A transit vehicle lighting system has a plurality of LED-based lighting fixtures for providing interior illumination. A control network comprises a plurality of slave nodes for controlling the LED-based lighting fixtures, and a master node for controlling the slave nodes. The master node may be connected to the slave nodes by a combined power/communication bus in a daisy chain fashion. The slave node may include a power regulator and a controller for providing a target current command to the power regulator, and may adjust the target current based upon temperature measurements or a recorded age of the LEDs. An optical sensor may provide automatic dimming. A reduced number of LEDs may be used in an emergency mode. The lighting fixture may include a ceiling panel fixture and a riser panel attachable by way of a hinge mechanism.