A controller switching a display mode of a display panel. A processor provides a first initial signal and switches to a first display mode when a select signal is asserted. A gate driver simultaneously activates the gate electrodes in a first gate electrode group when receiving the first initial signal, sequentially activates the gate electrodes in a second gate electrode group when the first gate electrode group is activated, and simultaneously activates the gate electrodes in a third gate electrode group when the second gate electrode group is activated. A data driver provides corresponding image data to a data electrode depending on the activated gate electrodes when the first, second, or third gate electrode group is activated.