scholarly journals An AMOLED AC-Biased Pixel Design Compensating the Threshold Voltage andI-RDrop

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Ching-Lin Fan ◽  
Hui-Lung Lai ◽  
Yan-Wei Liu
Keyword(s):  
Threshold Voltage ◽  
Integrated Circuit ◽  
Low Voltage ◽  
Voltage Drop ◽  
Light Emitting Diode ◽  
Power Line ◽  
Silicon Thin Film ◽  
Active Matrix ◽  
Voltage Variation ◽  
Voltage Deviation

We propose a novel pixel design and an AC bias driving method for active-matrix organic light-emitting diode (AM-OLED) displays using low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs). The proposed threshold voltage andI-Rdrop compensation circuit, which comprised three transistors and one capacitor, have been verified to supply uniform output current by simulation work using the Automatic Integrated Circuit Modeling Simulation Program with Integrated Circuit Emphasis (AIM-SPICE) simulator. The simulated results demonstrate excellent properties such as low error rate of OLED anode voltage variation (<0.7%) and low voltage drop ofVDDpower line. The proposed pixel circuit effectively enables threshold-voltage-deviation correction of driving TFT and compensates for the voltage drop ofVDDpower line using AC bias on OLED cathode.

An active-matrix organic light-emitting-diode pixel circuit for the compensation of I × R voltage drop in power line

2007 ◽  
Vol 15 (8) ◽  
pp. 541 ◽  
Author(s):  
Sang-Hoon Jung ◽  
Hong-Koo Lee ◽  
Tae-Joon Ahn ◽  
Chang-Yeon Kim ◽  
Chang-Dong Kim ◽  
...  
Keyword(s):  
Voltage Drop ◽  
Light Emitting Diode ◽  
Power Line ◽  
Active Matrix ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light ◽  
Pixel Circuit

Backplane Requirements for Active Matrix Organic Light Emitting Diode Displays

2006 ◽  
Vol 910 ◽  
Author(s):  
Arokia Nathan ◽  
Denis Striakhilev ◽  
Reza Chaji ◽  
Shahin Ashtiani ◽  
Czang-Ho Lee ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Power Efficiency ◽  
Low Voltage ◽  
Crystalline Silicon ◽  
Light Emitting Diode ◽  
Threshold Voltage Shift ◽  
Active Matrix ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Organic Light

AbstractOrganic light emitting diode (OLED) displays are a serious competitor to liquid crystal displays in view of their superior picture quality, higher contrast, faster on/off response, thinner profile, and high power efficiency. For large area and/or high-resolution applications, an active matrix OLED (AMOLED) addressing scheme is vital. The active matrix backplane can be made with amorphous silicon (a-Si), polysilicon, or organic technology, all of which suffer from threshold voltage shift and/or mismatch problems, causing temporal or spatial variations in the OLED brightness. In addition, the efficiency of the OLED itself degrades over time. Despite these shortcomings, there has been considerable progress in development of AMOLED displays using circuit solutions engineered to provide stable and uniform brightness. Indeed the design of AMOLED pixel circuits, particularly in low-mobility TFT technologies such as a-Si, is challenging due to the stringent requirements of timing, current matching, and low voltage operation. While circuit solutions are necessary, they are not sufficient. Process improvements to enhance TFT performance are becoming inevitable. This paper will review pertinent material requirements of AMOLED backplanes along with design considerations that address pixel architecture, contact resistance, and more importantly, the threshold voltage stability and associated gate overdrive voltage. In particular, we address the question of whether conventional PECVD can be deployed for high mobility and high stability TFTs, and if micro-/nano-crystalline silicon could provide the solution.

scholarly journals An AMOLED Pixel Circuit Based on LTPS Thin-film Transistors with Mono-Type Scanning Driving

Electronics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 574
Author(s):  
Jianyuan Ke ◽  
Lianwen Deng ◽  
Liying Zhen ◽  
Qing Wu ◽  
Congwei Liao ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Light Emitting Diode ◽  
Monte Carlo Analysis ◽  
Internal Resistance ◽  
Silicon Thin Film ◽  
Active Matrix ◽  
Ir Drop ◽  
Control Functions ◽  
Pixel Circuit

Using low-temperature poly-silicon thin-film transistors (LTPS TFTs) as a basis, a pixel circuit for an active matrix organic light-emitting diode (AMOLED) with narrow bezel displays was developed. The pixel circuit features mono-type scanning signals, elimination of static power lines, and pixel-integrated emitting control functions. Therefore, gate driver circuits of the display bezel can be simplified efficiently. In addition, the pixel circuit has a high-resolution design due to an increase of the pulse width of the scan signal to extend the threshold voltage and internal–resistance drop (IR drop) detection period. Further, regarding the influences of process–voltage–temperature (PVT) variation in the pixel circuit, comparison investigations were carried out with the proposed circuit and other pixel circuits with mono-type scanning signals using Monte Carlo analysis. The feasibility of the proposed pixel circuit is well demonstrated, as the current variations can be reduced to 2.1% for the supplied power reduced from 5 V to 3 V due to IR drop, and the current variation is as low as 10.6% with operating temperatures from –40 degrees to 85 degrees.

A Novel Voltage-Programmed Pixel Circuit with Poly-Si TFTs for AMOLED Displays

2018 ◽  
Vol 27 (14) ◽  
pp. 1850221
Author(s):  
Zunkai Huang ◽  
Li Tian ◽  
Hui Wang ◽  
Songlin Feng
Keyword(s):  
Threshold Voltage ◽  
Light Emitting Diode ◽  
Active Matrix ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Electrical Stress ◽  
Organic Light ◽  
Pixel Circuit ◽  
Display Performance

In this paper, we propose a novel voltage-programmed pixel circuit with polysilicon thin–flim transistors (poly-Si TFTs) for active matrix organic light-emitting diode (AMOLED) displays, which consists of one programming transistor, one driving transistor, four switching transistors and two storage capacitors, respectively. Specifically, the proposed pixel circuit is able to not only efficiently compensate for the threshold variations of TFTs, but also largely suppresses the electrical degradations of the devices caused by the long-term electrical stress. Moreover, the mobility variation of the driving transistor can be compensated as well. The simulation has been performed by HSPICE, and results indicate that the average values of nonuniformities are, respectively, 7.3% as the threshold-voltage varies by [Formula: see text][Formula: see text]V and 2.1%, as the mobility of the driving transistor varies by [Formula: see text]%, both of which are much lower than that of the conventional two-transistor and one-capacitor (2T1C) pixel. Furthermore, since the OLED is reverse-biased during the nonemission phases, the lifetime of OLED will be extended naturally. As a consequence, the proposed pixel circuit can substantially improve the display performance.

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