Compensation pixel circuit to improve image quality for mobile AMOLED displays

Chih-Lung Lin, Po Chun Lai, Li Wei Shih, Chia Che Hung, Po Cheng Lai, Tsu Yuan Lin, Kuang Hsiang Liu, Tsang Hong Wang

Research output: Contribution to journalArticle

Abstract

This paper proposes a new pixel circuit using lowerature polycrystalline silicon thin-film transistors (LTPS TFTs) for use in mobile active matrix organic light-emitting diode (AMOLED) displays. The purpose of a pixel circuit is to supply stable and uniform currents to current-driving devices of OLEDs. The proposed pixel circuit uses overlapping compensation times to extend the period of precise sensing of VTH variations of LTPS TFTs. Moreover, the proposed circuit prevents a current from flowing into an OLED when the OLED is not operated in the emission stage to avoid image flicker. An 1.3-in panel that uses the proposed pixel circuit is fabricated. Measurement results verify that the increased TCOMP of 33.3 μs results in higher contrast ratio and lower required data voltages than those at TCOMP values of 4.3 and 2.2 μs. Red, green, and blue images displayed by the fabricated panel with a TCOMP of 33.3 μs with a 255 gray level are all much more uniform than with TCOMPS of 4.3 and 2.2 μs. White images with a TCOMP of 33.3 μs for 16 and 8 gray levels on the fabricated panel confirm that the serious line and spot defects in the images with TCOMP values of 4.3 and 2.2 μs are effectively eliminated. Therefore, the proposed pixel circuit is suitable for use in mobile AMOLED displays.

Original languageEnglish
Article number8551265
Pages (from-to)489-500
Number of pages12
JournalIEEE Journal of Solid-State Circuits
Volume54
Issue number2
DOIs
Publication statusPublished - 2019 Feb 1

Fingerprint

Organic light emitting diodes (OLED)
Image quality
Pixels
Display devices
Networks (circuits)
Thin film transistors
Polysilicon
Compensation and Redress
Defects
Electric potential

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

Cite this

Lin, C-L., Lai, P. C., Shih, L. W., Hung, C. C., Lai, P. C., Lin, T. Y., ... Wang, T. H. (2019). Compensation pixel circuit to improve image quality for mobile AMOLED displays. IEEE Journal of Solid-State Circuits, 54(2), 489-500. [8551265]. https://doi.org/10.1109/JSSC.2018.2881922
Lin, Chih-Lung ; Lai, Po Chun ; Shih, Li Wei ; Hung, Chia Che ; Lai, Po Cheng ; Lin, Tsu Yuan ; Liu, Kuang Hsiang ; Wang, Tsang Hong. / Compensation pixel circuit to improve image quality for mobile AMOLED displays. In: IEEE Journal of Solid-State Circuits. 2019 ; Vol. 54, No. 2. pp. 489-500.
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Lin, C-L, Lai, PC, Shih, LW, Hung, CC, Lai, PC, Lin, TY, Liu, KH & Wang, TH 2019, 'Compensation pixel circuit to improve image quality for mobile AMOLED displays', IEEE Journal of Solid-State Circuits, vol. 54, no. 2, 8551265, pp. 489-500. https://doi.org/10.1109/JSSC.2018.2881922

Compensation pixel circuit to improve image quality for mobile AMOLED displays. / Lin, Chih-Lung; Lai, Po Chun; Shih, Li Wei; Hung, Chia Che; Lai, Po Cheng; Lin, Tsu Yuan; Liu, Kuang Hsiang; Wang, Tsang Hong.

In: IEEE Journal of Solid-State Circuits, Vol. 54, No. 2, 8551265, 01.02.2019, p. 489-500.

Research output: Contribution to journalArticle

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AU - Lin, Chih-Lung

AU - Lai, Po Chun

AU - Shih, Li Wei

AU - Hung, Chia Che

AU - Lai, Po Cheng

AU - Lin, Tsu Yuan

AU - Liu, Kuang Hsiang

AU - Wang, Tsang Hong

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AB - This paper proposes a new pixel circuit using lowerature polycrystalline silicon thin-film transistors (LTPS TFTs) for use in mobile active matrix organic light-emitting diode (AMOLED) displays. The purpose of a pixel circuit is to supply stable and uniform currents to current-driving devices of OLEDs. The proposed pixel circuit uses overlapping compensation times to extend the period of precise sensing of VTH variations of LTPS TFTs. Moreover, the proposed circuit prevents a current from flowing into an OLED when the OLED is not operated in the emission stage to avoid image flicker. An 1.3-in panel that uses the proposed pixel circuit is fabricated. Measurement results verify that the increased TCOMP of 33.3 μs results in higher contrast ratio and lower required data voltages than those at TCOMP values of 4.3 and 2.2 μs. Red, green, and blue images displayed by the fabricated panel with a TCOMP of 33.3 μs with a 255 gray level are all much more uniform than with TCOMPS of 4.3 and 2.2 μs. White images with a TCOMP of 33.3 μs for 16 and 8 gray levels on the fabricated panel confirm that the serious line and spot defects in the images with TCOMP values of 4.3 and 2.2 μs are effectively eliminated. Therefore, the proposed pixel circuit is suitable for use in mobile AMOLED displays.

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