Solid State Lighting Driver Failure Detection Circuit
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Solution Overview
Problem
Solid state light engines face premature failure and damage due to individual light source failures, which cause voltage surges and excess current diversion, shortening the lifespan of remaining sources and potentially damaging the driver circuit.
Innovation Solution
A driver circuit with a light engine controller that monitors output voltage changes, reduces drive current to maintain nominal operating values, and communicates failure information to a system controller for identification and replacement, ensuring dynamic adjustment of drive current to compensate for failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid state light sources are connected in parallel strings without failure detection, then the system can operate continuously, but individual failures cause voltage surges and excess current that shorten the lifespan of remaining sources and may damage the driver circuit
Solution Approach 1:
The system performs preliminary detection of light source failures by monitoring voltage changes before excess current can cause damage. The controller detects voltage deviations that indicate failed light sources and takes corrective action by adjusting drive current before the remaining light sources are damaged, thus preventing premature failure while maintaining system continuity
Solution Approach 2:
The system implements feedback control by continuously monitoring the output voltage of the driver circuit and comparing it against expected values. When a voltage change indicating a failure is detected, the controller provides feedback to adjust the drive current, creating a closed-loop system that maintains reliability while protecting the lifespan of remaining light sources
2Reliability
If the drive current is reduced in response to detected failures, then the output voltage returns to nominal operating values and remaining light sources are protected, but the light output intensity decreases
Solution Approach 1:
The system changes the drive current parameter dynamically based on detected failures. When a failure is detected through voltage monitoring, the controller adjusts the drive current parameter to a reduced level that protects remaining light sources while maintaining adequate illumination. This parameter adjustment resolves the contradiction by adapting the operating conditions to the current system state
3Reliability
If voltage monitoring and failure detection circuits are added to the driver circuit, then failures can be detected and responded to, but the device complexity increases
Solution Approach 1:
The driver circuit is designed to perform multiple functions: it provides drive current to the light sources, monitors output voltage for failure detection, and adjusts drive current in response to detected failures. By integrating these functions into a single multi-functional circuit rather than separate components, the system achieves reliable failure detection while minimizing the increase in device complexity
Data Source
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AI summary
Systems and method for detecting failure in solid state light sources and recovering from the failure are provided. A light engine including a controller circuit and strings of solid state light sources emits light in response to drive current provided by a driver circuit. The controller circuit monitors an output voltage of the driver circuit, and detects a failure of one of the solid state light sources. The failure is associated with a change in the output voltage of the driver circuit. The controller circuit then transmits a first signal to the driver circuit in response to detecting a failure, and the driver circuit is configured to decrease the drive current in response to the first signal.