P‐41: A Combined PAM / PWM Driving Scheme for High Uniformity of Micro‐LED Displays

Abstract

This paper handles further development of a proposed combined PAM and PWM driving scheme for Micro‐LED displays. A prototype display which consists of 64x3x64 pixels is driven by a combined PAM and PWM scheme. The occurring non‐ uniformity of Micro‐LED displays is improved by two extensions in the driving scheme. First, an analog bit for high luminance compensation and second, a compensation method that uses the high gray scale of digital driving schemes.

An analog PWM pixel circuit with shaping function for low grayscale display of Micro-LEDs

“…The digital PWM driving method is to divide one frame into some subframes, which can achieve accurate grayscale control since the PWM signal is generated by the peripheral circuit of the panel [12,13]. For the analog PWM driving method, the PWM control signal is generated by the comparison between the data voltage signal coupled with the sweep signal and the threshold voltage of PWM TFTs [14][15][16][17][18][19][20][21][22][23][24]. However, the PWM signal exists a long rising/falling time since the sweep signal voltage slowly cross the PWM TFT subthreshold region, resulting in image distortion especially in the low grayscale display.…”