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This brief suppresses threshold voltage (${V}_{\text {TH}}$) variations in low-temperature polycrystalline-silicon thin-film transistors (LTPS TFTs) with a new current scaling ratio modulation method for the application of active-matrix organic light-emitting diode displays. With a newly proposed 3T2C LTPS TFT-based pixel circuit, high-current scaling ratios at low gray levels and low ratios at high gray levels are achieved. Thus, the programming time at low gray levels can be reduced, and the driving currents of the OLED are efficiently generated over the entire data range without consuming extra power for the current source. The driving currents are also independent of the threshold voltage of the driving TFT and the power line voltage, guaranteeing the uniformity of the current. Simulation results demonstrate that the relative current error rates are below 3.7% as the threshold voltage varies ±0.5 V and below 5.3% as the threshold voltage varies ±0.5 V and the power line voltage drops by 1 V; the programming time can be as short as only $12~\mu \text{s}$. [ABSTRACT FROM AUTHOR]

This work proposes a new pixel structure based on amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs) and a parallel addressing scheme for high-resolution active-matrix organic light-emitting diode (AMOLED) displays. The proposed circuit compensates for the nonuniformity of luminance that is caused by shifts in the threshold voltage (${{V}}_{{\rm{TH}}}$) and mobility of driving TFTs. Measurement results verify that the parallel addressing scheme successfully extends the compensation time and accurately detects the ${{V}}_{{\rm{TH}}}$ of the driving TFT. Moreover, the proposed circuit reduces the variations of OLED luminance from more than 83% to less than 13% when the ${{V}}_{{\rm{TH}}}$ and mobility of driving TFT shifts by 1 V and 30%, respectively, and the ${{V}}_{{\rm{TH}}}$ of OLED varies from 0 to 0.9 V. [ABSTRACT FROM PUBLISHER]

This letter presents a new pixel circuit reaching simultaneous compensation for a threshold voltage ( $V_{{\rm{TH}}}$) shift of normally-off and normally- on a-IGZO TFTs, as well as luminance drop of an OLED device for ultrahigh-definition active-matrix organic light-emitting diode displays. Simulation results demonstrate the successful detection of a 1 V shift of threshold voltage despite normally-off and normally-on characteristics by the novel source-follower structure. Furthermore, the interdependence between luminance and threshold voltage shift of the OLED device is measured. Based on the simulations using the measured interdependence, the luminance drop caused by OLED aging is suppressed below 5% at different data voltages. [ABSTRACT FROM PUBLISHER]

This work presents a new pixel circuit based on low temperature polysilicon thin-film transistor (LTPS-TFT) for active-matrix organic light-emitting diode (AMOLED) displays. This circuit compensates for variations of threshold voltage (VTH) and mobility of TFTs and utilizes the parallel addressing scheme to extend the compensation time for ensuring the feasibility of application for high resolution displays. Based on the simulation results, the relative current error rates of proposed driving scheme are all lower than 2.1% for 0.5V VTH variations of TFTs and are all lower than 2.5% for 30% mobility variations of TFTs, showing effective compensation for variations of threshold voltage and mobility of TFTs. [ABSTRACT FROM AUTHOR]

This paper presents a simple pixel structure that uses the voltage-programmed method to compensate for the electrical characteristic variations in low-temperature polycrystalline-silicon thin-film transistors and the current-resistance ( \(I\) – \(R\) ) voltage drop in the power line for active-matrix organic light-emitting diode displays. Based on the experimental results, the functionality of the pixel circuit can be operated correctly during each operation phase. Moreover, the pixel current exhibits high uniformity against the threshold voltage and mobility variations in the driving TFT. [ABSTRACT FROM AUTHOR]

This work presents a simple pixel circuit that utilizes two low-temperature polycrystalline-silicon thin-film transistors (LTPS TFTs) and one capacitor for active-matrix organic light-emitting diode (AMOLED) displays with voltage-programmed method. According to simulation results under 120 Hz frame rate and Full-HD resolution, the relative current error rates with ±0.5 V threshold voltage variation of the driving TFT are less than 3.4% over entire range of data voltages. Therefore, the proposed pixel circuit effectively compensates for threshold voltage variation of the driving TFT, and it can be applied to small-sized and high-resolution displays. [ABSTRACT FROM AUTHOR]