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Proceedings Paper

Design of an improved data signal timing for an amorphous silicon active-matrix organic LED display
Author(s): Yan-ping Liao; Zhi-wei Zhang; Xi-bin Shao; Jin-e Liu; Guo-zhu Fu; Hai Jing; Fa-bin Qiu; Kai Ma
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Paper Abstract

The most critical issue in the design of an active matrix organic light emitting diode (AM-OLED) display pixel is the pixel to the pixel luminance uniformity. By substituting four-thin film transistor (TFT) pixel circuit for two-TFT pixel circuit, the luminous uniformity has great improved, but it requires more components than the two-TFT pixel circuit. There are some barriers needed to resolve to utilize hydrogenated amorphous silicon transistor to lit OLED, such as low field effect mobility, low output current and threshold voltage shift. In this article, a two-a-Si:H TFT pixel circuit was designed, which consisted of one named switching TFT and the other named driving TFT. The driving TFT gate line structure modified and a data signal timing improved were reported. The modified driving TFT can provide enough current about 30 microampere to lit OLED and the novel data signal timing can provide a constant current to OLED by restraining the driving TFT threshold voltage variation. In the novel data signal timing, the control signals to the driving TFT gate include a data signal and a reverse data signal. The signals alteration is performed either at a frame rate or at a line rate. By experiments, the driving TFT output current value is plotted as a function of the time in different reversed voltage value. When the magnitude of the positive data signal and the negative data signal is equal, the variety of ΔVth is smallest, about 1.28V after a fixed stressing time of 1.33×104min, which shows the novel data signal timing can improved the driving TFT output-input current stability.

Paper Details

Date Published: 26 January 2006
PDF: 5 pages
Proc. SPIE 6030, ICO20: Display Devices and Systems, 603008 (26 January 2006); doi: 10.1117/12.667364
Show Author Affiliations
Yan-ping Liao, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Chinese Academy of Sciences (China)
Zhi-wei Zhang, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Xi-bin Shao, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Ji Lin North Cai Jing Digital Electron Limited Corp. (China)
Jin-e Liu, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Chinese Academy of Sciences (China)
Guo-zhu Fu, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Hai Jing, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Ji Lin North Cai Jing Digital Electron Limited Corp. (China)
Fa-bin Qiu, Ji Lin Univ. (China)
Kai Ma, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Lanser Photo-Electronics Ltd. Corp. (China)


Published in SPIE Proceedings Vol. 6030:
ICO20: Display Devices and Systems

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