Improved optical feedback for OLED differential ageing correction

— To compete with LCDs and to meet standard display product specifications, OLED displays must have a high degree of tolerance to differential ageing or “burn-in.” A new optical feedback pixel circuit is presented that enables accurate differential ageing correction, can have low power consumption, and enables a high degree of non-uniformity correction. The circuit can be implemented in LTPS, and a-Si:H TFT technologies and circuits for both cases are shown. The a-Si:H approach is low cost and enables correction of both TFT threshold voltage drift and OLED degradation at the same time. The circuit analysis, operation, and technology will be described and results presented.