Liquid crystal display device and method for driving liquid crystal display device

A liquid crystal display device comprising:

• a liquid crystal panel having a common electrode, formed with an oxide semiconductor, and driven by both positive and negative power supplies;
• a power supply control circuit having a control output terminal and a power output terminal and configured to output, from the control output terminal, a control signal at an active level during a period set after the power is turned off and output, from the power output terminal, a power supply voltage that is maintained at an operating level, even after the power is turned off, until at least the start of the period;
• and
• a common electrode control circuit configured to discharge a residual charge remaining on the common electrode by connecting the common electrode to ground during the period,
• wherein the common electrode control circuit includes:
• a first capacitor;
• a discharge resistor connected to the first capacitor;
• a charge control circuit configured to charge the first capacitor using the power supply voltage so that the first capacitor has a predetermined voltage immediately before the period;
• a discharge control circuit configured to discharge the first capacitor through the discharge resistor when the control signal is at an active level;
• and
• a residual-charge-discharging switching element having a control terminal connected to a connection point between the first capacitor and the discharge resistor and configured to turn on during a period from when the discharge control circuit starts discharging the first capacitor until a voltage at the connection point reaches a predetermined level as a result of the discharge so that the common electrode is connected to ground.