The above-described liquid crystal device preferably further includes three electrodes for ion trapping, an average of the second periods of the AC signal is preferably an integral multiple (n times) of 6 of the first period of the common signal, and the AC signals applied to the three electrodes repeat a period of n×(6+1) and a period of n×(6?1).
According to this configuration, in each of the three electrodes, bias in the polarity of the potential can be eliminated by equalizing the durations in which the potential by the AC signal has a positive polarity and the durations in which the potential has a negative polarity. Eliminating bias in the polarity of the potential in each of the three electrodes configured for ion trapping makes it possible to sweep ionic impurities from the display region toward the outside without ionic impurities attracted by the electrodes being left behind.
In the above-described liquid crystal device, a frequency of the common signal is preferably from 60 Hz to 240 Hz, and a frequency of the AC signal is preferably from 0.1 mHz to 5 mHz.