Reducing image sticking in AMOLED displays with time‐ratio gray scale by analog calibration

Abstract

Abstract— Early loss of image uniformity has been a critical drawback of active‐matrix organic light‐emitting‐diode (AMOLED) displays operated in time‐ratio gray‐scale mode. This problem is addressed with an analog calibration technique which measures the voltage across each OLED for a given current and subsequently controls the supply voltage of pixels and the voltage drop across the driving th in‐film transistor (TFT) of each OLED. The uniformity of test cells, which were aged to produce image sticking in a chessboard pattern, were improved. A measure of image sticking, called the extracted image‐sticking value (EISV), was formulated, which is developed and used for the quantitative evaluation of the calibration method. OLED voltages over a range of about 0.35 V were compensated to produce more uniform OLED currents than those before aging. The variation of luminance associated with image sticking was reduced by about 40% for a full‐white image after between 2 and 10 hours of accelerated aging with a constant voltage of 8 V across an OLED.

Viewing angle and imaging multispectral analysis of OLED display light emission

“…They are clearly important for blue and green and more limited for the red. These short range fluctuations are certainly related to the current fluctuations due to I(V) fluctuations of the driving TFTs as already reported by other authors [18]. When the color fluctuations are computed from the same spectral data, there are in a range sensitive to human eye for the blue and green sub-pixels as shown in figure 16.…”

19.2: Distinguished Student Paper: Compensation of OLED I‐V‐Drift for Suppressing Image Sticking in A Digital AMOLED Display Module

“…As digital driving enables a very high luminance resolution, this can be done much easier and more precise at low cost by manipulating the image data as for analog driving. Analog compensation like presented in [1] needs a very accurate voltage resolution and thus is expensive.…”

Principle and validation of digital driving for active matrix organic light emitting diodes displays

“…This could be performed by monitoring the current through the OLEDs. A method for that is shown in section 4.2 or in the study of Shin …”