Vehicle LED Chain Short Circuit Detection via Coupling
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Solution Overview
Problem
Existing LED lighting systems for vehicles face challenges in detecting individual LED short circuits within LED chains due to varying voltage drops influenced by factors like age and temperature, making it difficult to distinguish a single LED short circuit from normal operation.
Innovation Solution
The system couples two LED chains with interrupter switches connected through a coupling component arrangement, where a voltage difference exceeding a predetermined value activates the interrupter switch in one chain, converting a single LED short circuit or a few short circuits into a detectable interruption in the other chain, utilizing minimal electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage drop across LED string is monitored to detect faults, then current interruption and complete short circuit can be detected, but individual LED short circuits cannot be reliably detected due to voltage fluctuations
Solution Approach 1:
The invention segments the monitoring function by introducing a separate monitoring LED string that is electrically coupled to the monitored LED string through a coupling component. This segmentation allows the monitoring function to be separated from the normal operation, enabling precise detection of individual LED short circuits without being affected by normal voltage fluctuations in the monitored LED string.
Solution Approach 2:
The invention uses a coupling component (such as a capacitor or inductor) as an intermediary between the monitored LED string and the monitoring LED string. This intermediary transfers voltage changes caused by individual LED short circuits to the monitoring LED string, making them detectable while filtering out normal operational variations.
2Measurement precision
If separate voltage measurement device is used to detect individual LED short circuits, then detection capability is improved, but device complexity increases
Solution Approach 1:
The monitoring LED string serves multiple functions: it acts as both a functional LED string (similar to other LED strings in the lighting device) and as a monitoring sensor for detecting short circuits in other LED strings. This multi-functionality eliminates the need for separate dedicated measurement devices, reducing overall system complexity while maintaining detection capability.
Solution Approach 2:
The system uses itself for monitoring by employing one of its own LED strings (the monitoring LED string) to detect faults in other LED strings. The voltage changes in the monitoring LED string directly indicate short circuits in the monitored LED string, eliminating the need for external or separate measurement equipment.
3Measurement precision
If interrupt switch control terminals are directly connected to monitor voltage, then short circuit detection is achieved, but circuit complexity and connection requirements increase
Solution Approach 1:
The coupling component serves as an intermediary that electrically connects the monitored LED string to the monitoring LED string without requiring direct physical connection between control terminals. This indirect connection through the coupling component simplifies the circuit architecture and reduces the number of direct connections needed while maintaining accurate voltage change detection.
Data Source
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AI summary
The invention relates to a device for supplying at least two LED chains (L1,L2,L3) with electricity and the possibility of detecting and then signalling a break in the current path through the LED chains. If an LED within a first LED chain is short-circuited, a sub-device is used to detect and/or subsequently signal a break in the current path within another LED chain of these at least two LED chains. The associated method for detecting the failure of an individual LED in a lighting device having at least two LED chains (L1,L2,L3) therefore comprises the steps: detecting a short circuit of an individual LED in a first LED chain by means of a first detection means (e.g. first transistor T1 and first diode D1 in conjunction with first resistor R1) and detecting the break caused thereby in the current flow through at least one other LED chain by means of a breaking means (e.g. transistor T2), and subsequently detecting this break in the current flow through the other LED chain by means of the break detection system already existing as required.