A Research On Driving Module Of Poly-Si TFT OLED

Polycrystalline silicon is used as the material of TFT (Thin Film Transistors) pixel circuit of AM-OLED because of the feature like high mobility of carriers, and easier to be integrated. However, non-uniformity of carrier mobility and threshold voltage may cause non-uniformed brightness of the screen. In this paper, the simulation of two LTPS (Low temperature Polycrystaline Silicon) TFTs pixel circuit with AIM-Spice is carried out to prove the feasibility of using digital grey scale technology to overcome the shortcomings of Poly-Si. A driving module based on Time-ratio Gray-scale (TRG) technology is designed and fabricated. The control center of the module composed with preprocessing part, states machine part, digital signal processing part and address generator part are designed on FPGA with Verilog HDL. When using TRG, the driving frequency would raise exponentially as the dimension and resolution of the display panel increased. In this paper, multiple ping-pang structure, parallel connection of driving ICs and dual-channel RAM output technology are introduced in order to decrease the driving frequency. With Digital Video Interface (DVI) as the video interface, SRAM as image buffer and FPGA as control center, the dynamic display of 5-inch full-color AM-OLED with 320×240 resolutions is realized. The gray level of the panel is 16, and the frame frequency of it is 60Hz.