P‐52: A New Current Programming Pixel Circuit for Compensating Luminance Degradation of AMOLED

Abstract

A new pixel circuit using low-temperature polycrystalline-silicon (LTPS) thin-film transistors for Active Matrix Organic Light Emitting Diodes (AMOLEDs) is presented. The proposed current programming circuit without charging time problem at low gray level compensates for the threshold voltage variation of TFT as well as OLED luminance decay. The simulation results demonstrate driving current of this circuit is independent of the variation of TFT and maintain luminance for long term operation.

Novel analog feedback current programming architecture compatible with 2-transistor 1-capacitor pixel for active matrix organic light-emitting diode displays

“…Simulation results for a programming current of 20 nA, presented in Fig. (a), show that the circuit charges the storage capacitor adequately fast because the output of OA2 is a low impedance node, thus any transient phenomena associated with the slow rise time of the voltage across the storage capacitor for low gray levels are eliminated …”

“…The first group (1) includes circuits that deploy from three to six TFTs per pixel for sensing the TFT characteristics in order to adjust the pulse of the data being programmed to the pixel. These topologies are utilized either for the electronic compensation of the threshold voltage shift, the mobility degradation, or both . However, as it is obvious to the reader, these approaches may be difficult to implement in high resolution mobile displays (cellphones and tablets) as the large area required by the complex pixel circuitry may not be available.…”

35.2: A New Feedback Current Programming Architecture for 2T1C AMOLED Displays

“…Simulation results for a programming current of 20nA, presented in figure 4(a), show that the circuit charges the storage capacitor adequately fast since the output of OA2 is a low impedance node, thus any transient phenomena associated with the slow rise time of the voltage across the storage capacitor for low gray levels are eliminated [8].…”

A novel sourceline voltage compensation circuit for embedded NOR flash memory

“…By adding a plurality of current sources controlled by the inverse of the input program data in Ref. [9], there exists a stable voltage drop from HVP to VSL even though the number of the cells to be programmed to data "0" changes. The drawback is that a big current which is similar to the program current exists even when no cells are to be programmed to data "0" and leads to unnecessary power dissipation.…”