Voltage‐programming method with transimpedance‐feedback technique for threshold voltage and mobility compensations in large‐area high‐resolution AMOLED displays

Abstract

Abstract— A voltage‐programming method with transimpedance‐feedback control technique is proposed for compensating threshold voltage and mobility variations of driving thin‐film transistors (TFTs) in large‐area high‐resolution polycrystalline‐silicon (poly‐Si) active‐matrix organic light‐emitting‐diode (AMOLED) displays. Those electrical characteristic variations of TFTs throughout a large‐area high‐resolution panel result in picture‐quality non‐uniformity of AMOLED displays. The simulation and experimental results of the proposed method show that the maximum emission‐current error for 30‐in. full‐high‐definition television (HDTV) applications is less than 1.9% when the mobility variation and the threshold‐voltage variation are ±12.5% and ±0.3 V, respectively. The proposed method is the best programming method for large‐area high‐resolution AMOLEDs among the published methods.

A digital driving method using pulse‐density modulation with a random dither matrix for higher motion image quality

“…Since the electric current through an OLED depends on the characteristic of the driving TFT, the uneven characteristics of the driving TFT directly degrade the image quality. Several compensation techniques have been reported for analog driving, such as voltage programming 9–11 and current programming techniques 12–16 . However, these methods require a complex panel structure and driver circuit.…”

Pixel structures to compensate nonuniform threshold voltage and mobility of polycrystalline silicon thin-film transistors using subthreshold current for large-size active matrix organic light-emitting diode displays

“…A fast current-programming pixel structure 9) was proposed to overcome the longprogramming-time problem using the current subtraction method, but this pixel structure requires more row line time to apply the data current. An external compensation method [10][11][12][13][14][15][16] compensates the variations of the threshold voltage and mobility of TFTs by modulating video input data, but the additional blocks such as external sensing blocks, calculation blocks, and additional memory blocks increase the system cost and complexity. A luminanceadjusting algorithm using a light sensor 17,18) also compensates the variations of the threshold voltage and mobility of TFTs by modulating video input data, but the operations of capturing the image and extracting parameters decrease the throughput owing to their long operation time.…”

New Driving Scheme to Improve Hysteresis Characteristics of Organic Thin Film Transistor-Driven Active-Matrix Organic Light Emitting Diode Display

“…Although correctly designing the transistor layout, such as the ratio of channel width to length, can improve on-state current and alleviate the low carrier mobility problem, the hysteresis characteristics of OTFTs still cause picture quality degradation due to the difficulty of gray scale reproducibility in AMOLED displays. Many driving schemes for AMOLED displays have been proposed to alleviate deteriorations due to the thin film transistor (TFT) characteristics; [6][7][8][9][10][11] however, they all are for polycrystalline silicon (poly-Si) TFTs. Because a poly-Si TFT has very high mobility, the non uniformity of its characteristics can be compensated within a short horizontal scanning period (1H).…”