P‐9: Student Poster: Two‐Mode PWM Driven Micro‐LED Displays with Dual‐Gate Metal‐Oxide TFTs

Abstract

A two‐mode pulse width modulation (PWM) pixel circuit is proposed for Micro‐LED display. The proposed driving method divides the consecutive 8 sub‐frames (256 gray levels) into low‐bit and high‐bit subframes, which are respectively driven by simultaneous emission (SE) and progressive emission (PE) modes. Compared with the traditional PWM driving scheme, the proposed one shows an increased effective luminous time ratio by 40% for a frame rate of 120Hz, which benefits higher power conversion efficiency. There are only 5 dual‐gate metal‐oxide transistors for the pixel circuit, while a source‐follower structure is adopted to extract the threshold‐voltage shift(ΔVth). Simulation results demonstrate that the current error rates can be reduced to 2% with ΔVth of ± 1 V for various grayscales.

38‐2: Multimodal Transistor‐Based 7T2C LTPS Pixel Circuit for Simultaneous PAM and PWM Control in μLED Display

“…As such, conventional pixel drive circuits (4), which regulate the current through the emitting element, are not suitable. Schemes have been proposed in which driving is performed in time (pulse width modulation -PWM) as opposed to absolute magnitude (pulse amplitude modulation -PAM) (1,3), although in practice, both types of control are required (2,(5)(6)(7)(8)(9), creating the necessity for complex pixel circuits (10) with numerous signals and elaborate driving techniques (11)(12)(13)(14).…”

38.2: An Accurate and Stable PWM Pixel Circuit Based on LTPO TFTs for AM‐Micro‐LED Display

“…The conventional pulse amplitude modulation (PAM) method can't accurately control the gray-scale of Micro-LED display, due to wavelength shifts and luminous efficiency variations for varied driving current amplitudes. Instead, the pulse width modulation (PWM) method, which presents different grayscale by adjusting the conduction time of each pixel with a constant on-current, is more suitable for driving Micro-LED display [2], [3].…”

P‐9: LTPO TFTs Based PWM Pixel Circuit for AM‐Micro‐LED Display with Falling‐time <10μs

“…Being different with conventional displays, Micro-LED performance is ultra-sensitive to driving-current variations since luminous efficiency (EQE) and emission wavelength vary with the driving-currents [3,4]. So, instead of the conventional pulse amplitude modulation (PAM) method, the pulse width modulation (PWM) with constant driving current is preferred to achieve high performance of Micro-LED displays [5][6][7][8].…”