Improving IR drop effect and power noise using digital OLED power in AMOLED display

This research proposes a new digital organic light emitting diode (OLED) power structure aimed at mitigating the IR drop effect, which refers to a voltage drop caused by current and resistance in active-matrix organic light-emitting diode (AMOLED) displays, and reducing the alternating current (AC) ripple of OLED power, thereby minimizing screen noise. We implemented an OLED power system that includes a buck converter, a digital pulse width modulation (PWM) control algorithm, and a video sync generator to address these AMOLED issues. We employed a predictive control and IR drop compensation algorithm to supply power to the AMOLED, thus improving panel uniformity. The performance was validated on a commercial 5.5-inch full high definition (FHD) AMOLED panel. As a result, we reduced the AC ripple of OLED power from approximately 20 to 13 mV. Additionally, The panel uniformity was successfully improved using the ELVDD voltage-based IR drop optimization algorithm. Numerically the panel pixel deviation was reduced from 31 gray to 7 gray levels at the 50gray solid pattern.