Enhancement of picture quality on ultra-low brightness by optimizing the electrical potential required for OLED charging in the AMOLED displays

Abstract

The principal causes of the poor picture quality on active matrix organic light-emitting diode (AMOLED) displays, operating under extremely low brightness and gray-scale conditions, were analyzed and verified by measuring and modelling of the electrical simulations. Through the analysis, it was found that the deteriorated picture quality was induced by a delayed saturation voltage, which means the electric potential difference between the initial voltage applied to the anode of the OLED (V init ) and the OLED saturated voltage (V sat ) for emission. This is because the deviations of pico-ampere-level currents and delayed OLED charging prior to light emission increased the saturation voltage when there were low driving currents. Thus, we optimized the voltage by increasing V init from −4.5 to −2.7 V, effectively eliminating image deterioration by reducing the OLED charging delay. Thus, the proposed approach opens up advancements of obtaining superior picture quality with ultra-low luminance, even in the dark illuminance environments. We discuss how OLED picture quality may be enhanced under low brightness, including the driving methods, design considerations, and processes involved.

Accurate Power Modelling Framework for Medical Images in Embedded System

“…The approximate estimation method based on software calculates the power consumption by constructing the power consumption model, which is simple and universal. At present, the power modeling method based on software approximate estimation has become the consensus of researchers at home and globally [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24].…”

“…Dalton et al [15] used the webcam installed on the laptop monitor to regularly capture images, and then determined whether the user was watching the monitor according to the face detection algorithm to enhance the power management. Na et al [16] believed that the degradation of image quality was caused by delayed saturation voltage. By reducing OLED charging delay to eliminate image degradation, they explored a new way to obtain excellent image quality under ultra-low brightness.…”

“…Then, the bitmap is sent to the display for showing. According to this process, the software-based OLED display power model can be divided into code level power model [15,19,21], image-level power model [13,14,19], circuit-level power model [16][17][18]20] and pixel-level power model [13,19,[22][23][24]. Lim et al [18] considered that the existing display power supply model did not take the impact of I-R voltage drop into consideration.…”

“…Since medical instruments and equipment are typically embedded equipment, the power modeling of their display images is helpful for medical image task scheduling, medical image analysis, prolonging the service life of the equipment, and improving the display effect. Considerable work has been done to study them [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Although the current power model can acquire the medical image's power, there is the issue of low accuracy [17,20,22,24].…”

P‐156: Late‐News Poster: Effect of Light Emission Delay on AMOLED Panel

“…Therefore, if it is able to define the characteristics of light emission delay, the luminance deviation (Mura) may be predicted. [1] In this paper, we analyze the effect of light emission delay on the Mura of AMOLED panel at low luminance by modeling the characteristics of light emission delay. The measured light emission profile was separated in units of 2 cycles and then normalized to a luminance value sufficiently saturated in the second cycle.…”