LED Backlight Failure Detection via Dynamic Voltage Comparison
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Solution Overview
Problem
Existing light-emitting element driving devices face challenges in reliably detecting short circuit and open circuit failures in LED backlights due to voltage fluctuations caused by sudden load variations, leading to incorrect operation and potential power loss.
Innovation Solution
A light-emitting element driving device that includes a failure detector monitoring the potential of nodes between light-emitting element arrays and the drive circuit, comparing monitored voltages across multiple arrays to cancel out variations in drive voltage and detect failures accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed reference voltage is used for failure detection in LED arrays, then the detection method is simple, but voltage fluctuations from load variations cause incorrect failure detection
Solution Approach 1:
The patent uses feedback control by continuously monitoring the actual drive voltage and adjusting the reference voltage dynamically. The failure detection comparator receives a dynamically adjusted reference voltage that tracks the actual drive voltage, ensuring accurate failure detection despite voltage fluctuations from load variations in the backlight system.
Solution Approach 2:
The patent changes the reference voltage parameter dynamically based on the actual drive voltage conditions. Instead of using a fixed reference voltage, the system adjusts the reference voltage to match the actual drive voltage, allowing the detection threshold to adapt to changing operating conditions and eliminate false failure detections.
2Adaptability or versatility
If monitored voltage varies due to drive voltage fluctuations, then the system responds to real-time conditions, but false failure detection occurs despite normal LED operation
Solution Approach 1:
The patent applies equipotentiality by ensuring that the reference voltage and actual drive voltage remain at equivalent potential levels. The system dynamically adjusts the reference voltage to match the actual drive voltage, creating an equipotential reference that eliminates detection errors caused by voltage variations while maintaining real-time adaptability.
3Reliability
If voltage converter controls drive voltage with feedback, then the LED array operates at constant current, but sudden load variations cause overshoot and voltage fluctuations
Solution Approach 1:
The patent applies beforehand cushioning by preparing a dynamically adjustable reference voltage that anticipates and compensates for upcoming voltage fluctuations. The failure detection system is pre-configured to adapt its threshold based on actual drive voltage conditions, cushioning against the impact of load variations and preventing false failure detections before they occur.
Data Source
AI summary
Short circuit failures and open circuit failures of light-emitting elements used for the backlight in an LCD panel can be reliably and easily detected. The voltage at the node between each series-connected light-emitting element array and a drive circuit is detected as a monitored voltage. A maximum detector detects the highest and a minimum detector detects the lowest of these monitored voltages. Short circuit or open circuit failure of a light-emitting element is detected by comparing the voltage difference between the maximum detector output and the minimum detector output with a specific reference voltage.