4.2: Integrated Scan Driver with Oxide TFTs Using Floating Gate Method

Abstract

An on-glass integrated scan driver is proposed for oxide thin film transistors (TFTs) with negative threshold voltage. A coupling capacitor and a TFT for setting the initial voltage to the gate of a TFT were added to minimize the off-state current. Simulated and measured results indicate that the proposed scan driver shows no ripple and fast rise time/fall time of scan outputs. Circuit operation was verified with a 14-inch AMOLED panel.

A low-power scan driver employing IZO TFTs including an AC–DC type output module

“…There are a few scan driver circuits integrated by MOTFTs using two negative power sources [7][8][9], series connected twotransistors (STT) structure with a feedback TFT [10], or floating gate method [11] to solve the problems induced by the leakage current at V gs = 0. In this paper, we focus on optimizing the output module of scan driver since the output module occupies most of the power consumption and restricts the speed of the scan driver.…”

Low-power and small-area scan driver using depletion-mode a-IGZO TFTs for ultra-high-resolution displays

“…Many researches have been done to make a scan driver integrated on display panels using oxide TFTs [4][5][6][7]. However, previously reported scan drivers adopted many external signals, such as seven [5,6] or eight signals [4].…”

“…However, previously reported scan drivers adopted many external signals, such as seven [5,6] or eight signals [4]. Increasing the number of clock signals creates more power consumption due to increasing the number of transitions of clock signals and the necessity of large area for signal lines.…”

“…Increasing the number of clock signals creates more power consumption due to increasing the number of transitions of clock signals and the necessity of large area for signal lines. Furthermore, output waveforms of the previously reported scan drivers [4][5][6] are overlapped, which induces deterioration in image quality because the pixel displays images of the previous row line during the overlapped line time with the previous scan signal. A scan driver with one clock signal and three reference voltages is reported in [7], but this circuit is too complex, using 22 TFTs per stage and has the effective turn-on time of switching TFTs in pixels by approximately half of a row line time because the driving voltage is not high enough during a half of a row line time.…”

“…gout [1] gout [2] gout [3] 20 V 10 µs gout [4] carry Conclusion: A small-area scan driver, which consists of 11 TFTs and two capacitors, is proposed for high resolution display panels using a-IGZO TFTs. The scan driver removes short circuit current from VDD to negative reference voltage or ground for low power consumption.…”