Novel Active-Matrix Micro-LED Display With External Compensation Featuring Fingerprint Recognition

This letter proposes a novel active-matrix (AM) micro light-emitting diode (micro-LED) display architecture featuring fingerprint detection. A new pixel circuit comprising four transistors and one capacitor (4T1C) is proposed to compensate for threshold voltages externally. The proposed AM micro-LED display does not need any additional light sources and sensors because an LED itself can be used for photosensors. The proposed 4T1C pixel circuit can isolate the effects of LED photocurrents caused by ambient lights and large LED capacitance from detecting the threshold voltage via external circuits. The proposed AM pixel circuit with oxide thin film transistors was fabricated using oxide thin film transistor process. The charges caused by the LED photocurrents were accumulated for 16.7 ms. The final voltages measured after 16.7 ms were −5.02 V and −1.53 V under irradiance of 0.05 W/m² and 1.54 W/m², respectively. It is verified that the proposed micro-LED pixel circuit could distinguish incident lights reflected from ridges and valleys of a fingerprint.