Active-Matrix Micro-LED Display Driven by Metal Oxide TFTs Using Digital PWM Method

摘要

This article presents a new micro-light-emitting diode (LED) pixel circuit driven by the digital pulsewidthmodulation (PWM) method, in which the threshold voltage compensation of the driving thin-film transistor (TFT) is included. A scan driver integrated by metal oxide (MO) TFTs is also designed to provide the scan signals for pixel circuits array. A micro-LEDs array with 76 x BBB x 78 and a scan driver with 80 stages are simultaneously fabricated by MO TFTs backplane with back-channel etch (BCE) structure. A respective micro-LED display is consequently realized by a peripheral driving system based on a field-programmable gate array (FPGA), which is used as a core control unit to synchronize the scan signals with the data signals. It is shown that the micro-LED in the pixel circuit can operate at a constant current even at the 5-mu s pulsewidth of the emission (EM) signal. Themicro-LED display can achieve 256 linear grayscales with an approximately 60 Hz flash rate under the minimum pulsewidth of 40 mu s of EM signal.

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