A flat display employs at least one high voltage different from logic
voltages. The display has a voltage detection unit and a drive control
signal control unit. The voltage detection unit is used to detect the
high voltage. The drive control signal control unit is used to control
drive control signals of the flat display in accordance with the detected
high voltage. This arrangement eliminates charging currents that are
applied to a display panel but have nothing to do on the actual
displaying of data, or reactive currents due to unnecessary switching
operations, thereby reducing power consumption.