New Low-Frame-Rate Compensating Pixel Circuit Based on Low-Temperature Poly-Si and Oxide TFTs for High-Pixel-Density Portable AMOLED Displays

Ching-Lin Fan; Wei-Yu Lin; Chun-Yuan Chen

doi:10.3390/mi12121514

New Low-Frame-Rate Compensating Pixel Circuit Based on Low-Temperature Poly-Si and Oxide TFTs for High-Pixel-Density Portable AMOLED Displays

Micromachines (Basel). 2021 Dec 5;12(12):1514. doi: 10.3390/mi12121514.

Authors

Ching-Lin Fan^{1

2}, Wei-Yu Lin¹, Chun-Yuan Chen¹

Affiliations

¹ Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Da'an Dist., Taipei City 106, Taiwan.
² Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Sec. 4, Keelung Rd., Da'an Dist., Taipei City 106, Taiwan.

Abstract

A new low-frame-rate active-matrix organic light-emitting diode (AMOLED) pixel circuit with low-temperature poly-Si and oxide (LTPO) thin-film transistors (TFTs) for portable displays with high pixel density is reported. The proposed pixel circuit has the excellent ability to compensate for the threshold voltage variation of the driving TFT (ΔV_{TH_DTFT}). By the results of simulation based on a fabricated LTPS TFT and a-IZTO TFT, we found that the error rates of the OLED current were all lower than 2.71% over the range of input data voltages when ΔV_{TH_DTFT} = ±0.33 V, and a low frame rate of 1 Hz could be achieved with no flicker phenomenon. Moreover, with only one capacitor and two signal lines in the pixel circuit, a high pixel density and narrow bezel are expected to be realized. We revealed that the proposed 7T1C pixel circuit with low driving voltage and low frame rate is suitable for portable displays.

Keywords: active-matrix organic light-emitting diode (AMOLED); compensating pixel circuit; low frame rate; low-temperature polycrystalline silicon and oxide (LTPO); portable displays.

Grants and funding

NSC 110-2221-E-011-106-/National Science Council