LED Series Fault Detection Using a Measuring Bridge Circuit
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Solution Overview
Problem
Existing LED lighting devices face challenges in reliably detecting defects, particularly short circuits, due to small voltage changes and increased complexity with multiple LED lamps in series, leading to high detection costs and limited reliability in series production.
Innovation Solution
The implementation of a measuring bridge circuit, formed by resistors and transistors, which detects detuning caused by defects in LED lamps, allowing for simple and cost-effective detection of short circuits without the need for complex additional cables or expensive electronics, using a Wheatstone bridge circuit design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of LED light sources connected in series is increased to achieve higher luminous efficacy, then the performance and cost-effectiveness are improved, but the reliability of short circuit detection deteriorates due to very small voltage curve changes
Solution Approach 1:
The patent divides the LED series circuit into multiple segments, each with its own detection circuit. Instead of attempting to detect faults in the entire long series circuit at once, the circuit is segmented into manageable sections, each monitored independently. This allows reliable detection of short circuits in individual segments even when many LEDs are connected in series overall.
Solution Approach 2:
The patent introduces intermediary measurement points and detection circuits between LED segments. These intermediaries monitor voltage changes locally, amplifying the detectable signal from short circuits. The detection circuit acts as a mediator that translates the small voltage changes caused by short circuits into reliable detection signals.
2Reliability
If conventional fault detection devices are used to detect short circuits in LED series circuits, then the detection capability is provided, but the device complexity and manufacturing cost increase due to extensive wiring connections and interfaces
Solution Approach 1:
The patent merges the detection function with the existing LED driver circuitry. The detection circuits are integrated into the same substrate or circuit board as the LED driver, sharing common components and wiring. This consolidation eliminates the need for separate detection devices and extensive additional wiring, reducing overall system complexity while maintaining detection capability.
Solution Approach 2:
The patent designs the driver electronics to perform multiple functions: both driving the LED series circuit and detecting faults within it. The same circuit board and power supply that drive the LEDs also provide the measurement functions for fault detection. This multi-functionality reduces the need for separate dedicated detection hardware and simplifies the overall system architecture.
3Measurement precision
If individual measurement monitoring of LED light sources is implemented to detect defects, then the detection accuracy is improved, but the manufacturing cost increases due to the large number of wiring connections and interfaces required
Solution Approach 1:
The patent segments the monitoring function into distributed measurement points along the LED series circuit. Each segment is monitored independently with simple local measurement circuits, providing adequate detection accuracy without requiring complex centralized monitoring. This segmentation allows individual LED or small group monitoring at manageable cost.
Solution Approach 2:
The patent implements self-service monitoring where the LED circuit itself provides the measurement signals. The voltage drops across individual LEDs or segments are naturally present during normal operation, and these existing voltage signals are used directly for fault detection without requiring additional power or complex measurement infrastructure. The system monitors itself using its own operating parameters.
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
This solution enables reliable and cost-effective detection of defects in LED lamps, reducing manufacturing costs and ensuring efficient operation even with large numbers of LED lamps, by using inexpensive and easily available components to form a robust measuring bridge circuit.
Implementation Method 1
the detection device, together with the first LED light source and the second LED light source, forms a first measuring bridge circuit
Data Source
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AI summary
The invention relates to an LED lighting device (1) having: an LED lamp series circuit (2) with a first LED lamp (3) and a second LED lamp (5) which is coupled to the first LED lamp (3) via a lamp coupling point (4); an anode (6); a cathode (7); driver electronics (8) for connection to the anode (6) and the cathode (7) for operation of the LED lamp series circuit (2); and a detection device (9) for detecting a defect in the first LED lamp (3) and the second LED lamp (5). The detection device (9), together with the first LED lamp (3) and the second LED lamp (5), forms a first measuring bridge circuit (10). The invention also relates to a motor vehicle (36) having an LED lighting device (1) according to the invention.