The Scan Driver Research Based On Metal Oxide TFTs

In recent years, with the development of the large-area high-definition display, 3D display and flexible display, metal oxide thin film transistors(MOTFTs) have received much attention for them probable substituting a-Si:H TFTs or low-temperature poly-Si TFTs in AMOLED(active-matrix organic light emitting diodes) and AMOLCD(active-matrix liquid crystal displays) due to the advantages of high mobility, good uniformity, a low-cost room-temperature fabrication process, and the compatibility with transparent or flexible application. By integrating scan driver with TFTs on the panel, the display systems can be cheaper and thinner.To fit for the developing trend of low power consumption and high resolution in display, the paper focuses on the low-power and high-speed output research of scan driver and design the scan driver integrate by MOTFTs.In the reasearch of low-power scan driver, we analyze the advantages and disadvantages of the AC-AC type output module and the DC-DC type output module. Forreduce the dynamic power consumption of the AC-AC type output module and the rise time of the DC-DC type output module, wepropose anoutput module call as AC-DC type output module. Following the previous study,we propose a scan driver employing the AC-DC type ouput module. 46 stages of the scan driver are fabricated by integrating IZO TFT with BCE structure on the glass. For comparingwith the scan driver employing the AC-AC type output module, the measured power consumption for one stage of the proposed scan driver with AC-DC type output module is reduced by57%.On the other hand, we analyze the disadvantages of the diode-connected inverter and the clock-controlled inverter. For reduces the static power consumption of the diode-connected inverter and the dynamic power consumption of the clock-controlled inverterremarkably, we proposed a novel inverter call as feedback inverter.Following the previous study, we proposed a scan driver employing the feedback inverter. In one stage the proposed scan driver only a small-size TFT connects the clock signal, which reduces the dynamic power consumption considerably.48 stages scan driver of proposed are fabricated by integrating IZO TFT with BCE structure on flexible substrate.It is measured that the power consumption of one stage for the proposed scan driver is 18.3μW,Compare with the previous single-clock-controlled scan driver, the measured power consumption of the proposed scan driver is reduced by 44.8%. In a word, for our proposed scan driver, the power consumption is reduced significantly.In the reasearch of high-speed scan driver, we analyze the diadevantages of conventional input module and output module. For raise the gate voltage of the output transistor, we proposed a new input module and a new output module.A bi-side scan driver including these two modules was proposed. The SPICE simulation was performed to analyze 120 stages scan driver of proposed. It is shown that the gate voltage of pull-up TFT increased by 40.1% when switch to low, while increasedby144.4% when switch to high, in a word, the rise time and fall time of the proposed scan driver reduce 44.4% compare with the previous scan driver with AC-AC type output module.