Trailer LED Outage Detection Circuit Using Fault Current Pulses
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Solution Overview
Problem
Traditional bulb outage detection systems fail to detect LED failures due to low current drops, complicating detection in vehicles with mixed incandescent and LED lamps, and lack of standardization in the U.S. for reporting or detecting failed lamps.
Innovation Solution
A circuit system with a load element, detection circuit, and power control circuit that increases power dissipation when an LED fails, using components like PTC thermistors to generate distinctive current pulses for fault detection, allowing differentiation between various LED locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional current drop detection systems are used, then incandescent bulb failures can be detected, but LED lamp failures cannot be detected due to insufficient current drop
Solution Approach 1:
The system changes the electrical parameters (current magnitude and duration) dynamically based on lamp type. For LED detection, it uses higher current magnitudes and shorter pulse durations to generate detectable signals without causing damage, while for incandescent bulbs it uses lower currents and longer durations. This parameter adaptation allows the same detection circuit to work with both lamp types effectively.
Solution Approach 2:
The detection circuit is designed to perform multiple functions: detecting failures in both LED and incandescent lamps using a single unified system. The circuit incorporates adjustable parameters and multiple detection modes that allow it to adapt to different lamp characteristics, eliminating the need for separate detection systems for different lamp types.
2Measurement precision
If higher current is used to detect LED failures, then detection sensitivity improves, but risk of damaging the LED increases
Solution Approach 1:
The system uses periodic current pulses rather than continuous current to detect LED failures. By applying short, intermittent pulses, the system accumulates detection data over time while limiting the total energy exposure to the LED. This periodic action allows sensitive detection while preventing thermal damage from excessive current.
Solution Approach 2:
The detection system dynamically adjusts current magnitude and pulse duration based on real-time feedback and lamp characteristics. The system starts with lower current pulses and increases magnitude only when necessary for detection, adapting the electrical parameters on-the-fly to maximize detection sensitivity while minimizing damage risk to the LED components.
3Device complexity
If vehicle operators must visually inspect lamps, then no additional detection system is needed, but operators cannot observe trailer lamp failures
Solution Approach 1:
The detection system enables the lighting system to self-diagnose failures automatically without requiring external visual inspection by operators. The circuit continuously monitors lamp status and self-identifies failures, providing reliable detection while maintaining relative system simplicity through automated operation.
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
Effectively detects LED failures by increasing current draw to a level detectable by vehicle systems, providing specific fault reporting to the operator, and avoiding false positives with incandescent bulbs.
Implementation Method 1
The load element can optionally be a thermistor and, furthermore, a Positive Temperature Coefficient (PTC) thermistor
Data Source
AI summary
A vehicle LED lighting outage detection circuit is disclosed for detecting a fault in the LED light and automatically increasing the power drawn from the light power supply in response to the fault. A complementary detection circuit is also disclosed for detecting the increased power draw and signaling a fault to an operator. The increased power draw can be selected to be in the form of a pulse that settles to a lower power draw state after a time to avoid excessive and wasteful power draw. The system can be mounted in a vehicle and, more particularly, to a semi-tractor truck.