Time-Ratio Grayscale and Hopping Scan with Current Uniformization for Thin-Film Transistor Driven Organic Light-Emitting Diode Displays

Abstract

A driving method using time-ratio grayscale and hopping scan with current uniformization has been developed for thin-film transistor (TFT) driven organic light-emitting diode displays. The easiness of pixel charging is superior to that of conventional current program driving. A TFT characteristic is measured, and design parameters are optimized. It is confirmed using a circuit simulator that this driving method maintains current uniformity and simultaneously overcomes charging shortage of the pixel circuit for low grayscale levels and current variation due to the shift of operating points. The influence of feed-through voltage can be neglected by optimizing design parameters. Moreover, it is also confirmed using an image simulator that grayscale linearity and luminance uniformity against the TFT characteristic deviation are much improved.

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“…However, AM‐OLEDs have ever been troubled with luminance unevenness and image sticking due to characteristic deviations and degradations of driving transistors and OLEDs . Although many kinds of driving methods have recently been reported, they cannot completely solve the abovementioned problems.…”