Development of a real-time monitoring system with uni-photodetector for LED long term reliability tests

In this paper, a fully automated, low-cost, real-time illuminance measurement system for LED long term reliability tests is proposed. The system has only one photodetector to measure the illuminance of all samples inside the test chamber during the reliability test. With a proprietary algorithm, a single photodetector can measure the illuminance of all samples in the chamber by sequential scanning. This system monitors and records the illuminance of each individual sample inside the test chamber. This provides continuous and reliable data for analysis and prediction of LED lifespan. It does not require suspending the reliability test for sample inspection and can automatically analyze the time-to-failure of samples. The proposed system can significantly reduce the time required for data acquisition and measurement errors. This paper also compares the results obtained from the proposed system and the conventional periodic inspection to highlight the merits of the new system.