P‐8: A New Hybrid Analog‐Digital Driving Method to Improve AMOLED Lifetime

Abstract

We propose a new hybrid pixel driving method that combines conventional digital driving with analog compensation for the declining electrical performance that occurs as OLEDs age. Image uniformity, and thus display lifetime, is improved by directly measuring the variation in OLED voltage at each pixel for a given OLED current level and then controlling the voltage drop across its driving TFT of an individual pixel.

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

“…It also includes a reverse bias operation which restores the I-V characteristics of the OLEDs. 18 Simulation results suggested that a longer time to image sticking may be attainable with this analog calibration method. In this paper, we present an improvement on this earlier method, a performance measure to evaluate image sticking, and experimental results obtained from test cells with real devices.…”

Quantitative evaluation of image sticking on displays with different gradual luminous variation

“…Image A was produced using a driving method with no compensation for image sticking, whereas image B was obtained using systematic compensation circuits which measure OLED voltages and refer to a look-up table. 7 In addition to image sticking, image A exhibits long-range luminous variation: we can see that the lower right-hand area of image A is darker than the rest of the image. Image B shows that systematic compensation almost eliminates this long-range non-uniformity (LRNU), and also reduces image sticking.…”

“…and (6b) The extracted reference values are used for normalization, which eliminates the LRNU in the measured luminance values. The normalized luminance of the block in the m-th row and n-th column can be computed as follows: (7) where 1 ≤ m ≤ M and 1 ≤ n ≤ N.…”

“…Various studies have examined the cause material and mechanism of image sticking, proposed improvements in structure and fabrication processes to retard the image sticking, and developed compensative driving methods to relieve image sticking. [3][4][5][6][7] Quantitative methods of evaluating image sticking have also been introduced to control product quality or assess the effectiveness of various remedies. [8][9][10][11][12] Experiments designed to assess the effect of cause material and structure on the image sticking may be satisfactorily performed by observing a limited region of a display area.…”

P‐188L: Late‐News Poster: Quantification of Image Sticking for Images with Different Long‐Range Non‐Uniformity

“…2(b), image B, and the ML difference between adjacent rectangles is reduced small. This is achieved by a compensation method that controls a supply voltage and a voltage drop across a driving thin film transistor (TFT) and that makes the OLED current uniform [5]. On the other hand, the LRNU remains significant in Fig.…”