Self-compensated control scheme for improving organic LED luminance uniformity in WSN

A new driving scheme with hysteresis control for 2×10 PMOLED (passive matrix organic light) is presented, intended to improve the lifetime of each pixel and thus solve the luminance non-uniformity issue. The newly-elaborated method detects junction voltage and generates programmable driving current based on the junction voltage increases in the aged pixels. Furthermore, a digital hysteresis control approach is introduced to maintain the driving current within a certain range, which is according to the PMOLED I/V curve. Simulation result shows that as the degraded PMOLED pixel has a higher voltage across the sensing resistor, its driving current is adjusted to be larger correspondingly. Experimental results indicate that the pixel with higher duty cycle is brighter than the one with lower duty cycle, and the degraded pixel can reach the same brightness as the normal one with hysteresis control. This high performance PMOLED will be used as the wireless sensor monitor.