According to one embodiment, a pixel signal from a memory is supplied to an arbitrary pixel. A controller selectively switches a scanning frequency of common electrodes including a touch detection system, between a higher frequency and a lower frequency, and allocates banks in the memory, each bank having a capacity of a fixed number of items of the pixel data. The controller defines one unit including a group of lines of the pixel data, sets a line number of the one unit to the fixed number when the scanning frequency is the higher frequency, and sets the line number of the one unit to another line number which is greater than the fixed number when the scanning frequency is the lower frequency.