Low-power driving methods for TFT-LCDs

The major factor of the power consumption of the driving LSIs for TFT-LCDs is AC power consumption stemming from charging and discharging data lines that have quite large parasitic capacitance. Since the AC power consumption is linearly proportional to the supply voltage of the driver circuits, the number of data lines and its parasitic capacitance, voltage swing and operating frequency. In this paper, therefore, we review the low power driving methods with four categories. The (COM) alternation method can reduce both the supply voltage and voltage swing. And there were several panel structure and driving methods for reducing the number of data lines in the TFT-LCD panel. Both multi-field driving method and a recent trend of embedded memory in pixel are focused on reducing the operating frequency. Finally, there are several researches to reduce the voltage swing with using energy recovery such as charge sharing method that is very simple and its maximum power saving efficiency is 50% and triple charge sharing method, stepwise source driving method and L2C energy recovery circuits whose power saving efficiency are up to 66.6%, 78% and 78.8%, respectively.