With a rapid development of the multimedia society, the technique for semiconductor elements and a display apparatus has got a great and rapid progress.
In terms of the displays, an Active Matrix Organic Light-Emitting Diode (AMOLED) display meets those characteristic requirements for a display in the multimedia era, because it has advantages such as no limitations on an angle of view, a low manufacture cost, a high response speed (about hundred times and more of that of the liquid crystal), energy saving, self-luminous, being applicable to a direct-current driving for a portable device, a wider operation temperature scope, and a lighter weight while being miniaturized and thinned along with the hardware devices, and the like. Therefore, the Active Matrix Organic Light-Emitting Diode display has a great potential of development and may be desired to become a next generation of the new flat panel display and to replace the Liquid Crystal Display (LCD).
Currently, there are two ways of manufacturing the Active Matrix Organic Light-Emitting Diode display panel, one way of which is to utilize a process technique for Thin Film Transistors (TFTs) of the Low Temperature Poly-Silicon (LTPS), and the other way of which is to utilize a process technique for the Thin Film Transistors (TFTs) of the amorphous silicon (α-Si). Herein, the process technique for the Thin Film Transistors of the Low Temperature Poly-Silicon would need more processes for mask manufacturing craft and thus lead to an increasing of the cost. Therefore, the process technique for Thin Film Transistors of the Low Temperature Poly-Silicon is mostly applied to the panel having a small or medium size, while the process technique for the Thin Film Transistors of the amorphous silicon is mostly applied to the panel having a large size.
Generally, for an Active Matrix Organic Light-Emitting Diode display panel manufactured by the process technique for Thin Film Transistors of the Low Temperature Poly-Silicon, the thin film transistors in the pixel circuit may be P-type or N-type, but no matter whether the P-type or N-type transistors are selected to implement the organic light-emitting diode pixel circuit, the current flowing through an organic light-emitting diode may not only change with the changes caused by a long time stress in a turn-on voltage (Voled_th) of the organic light-emitting diode, but also vary with a threshold voltage shift (Vth shift) in the thin film transistor for driving the organic light-emitting diode. As a result, the brightness uniformity and the brightness constancy of the organic light-emitting display may be affected correspondingly.