Pixel current-programmed

Ashtiani, S.,J. Servati, P. Striakhilev, D. Nathan, A. (2005). A 3-TFT Current-Programmed Pixel Circuit for AMOLEDs. IEEE Trans. Electron Devices, Vol. 52, 0uly, 2005) 1514-1518, ISSN 0018-9383... 

Current-programmed pixels have the following advantages over voltage-programmed pixels ... 

A column driver for current-programmed AMOLED displays is difficult to implement using TFTs because currents do not lend themselves to simple sample-and-hold demultiplexing using switches. One approach is to use the same type of current sample-and-hold circuits described earlier for current-programmed pixels, but now placed on each column. 

Y. Hong, R. Hattori, and J. Kanicki, Novel poly-Si TFT pixel electrode circuits and current programmed active-matrix driving methods for AMOLEDs, SID Tech. Dig., 33, 618-621, 2002. 

R. Hattori, Y. Kuroki, and J. Kanicki, Analog-circuit simulation of the current-programmed active-matrix pixel electrode circuits based on poly-Si TFT for organic light-emitting displays, Proc. AM-LCD, 223-226, 2001. 

In 2001 Sony demonstrated a different four TET current-programmed approach using a current mirror, shown in Eigure 6.4.23 [52]. This pixel operates similarly to... 

FIGURE 6.4.22 Samoff four TFT self-compensating current-programmed AMOLED pixel. 

Additional discussion and analysis of the use of OTETs for AMOLED displays can be found in the literature [56,57], To date, only the two TFT pixel has been implemented with OTFTs, although a paper design for a current-programmed OTFT AMOLED pixel has been presented [57], It is only a matter of time before the more complex pixels that have been investigated using poly-Si and a-Si TFTs are tested with OTFTs. 

Sasaoka, T. et al., A 13.0-inch AMOLED display with top emitting structure and adaptive current mode programmed pixel circuit, SID Int. Symp. Dig. Tech. Papers, 32, 384, 2001. 

Fig. 7.1. Two architectures for display driving, (a) shows a single transistor architecture appropriate for latching and holding charge on the pixel for field driven display elements such as liquid crystal displays or e-Ink. (b) schematically shows the matrixed version of this element, (c) shows a two transistor voltage-programmed current driver appropriate for OLEDs. More advanced voltage and current programmed circuits are also possible, but require more transistors.

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