<p>There are provided a cathode voltage control part (10) for controlling a cathode electrode such that the electron emission from the cathode electrode is uniform; and a gate electrode driving part (12) for changing the voltage of a gate electrode in accordance with a video signal. The cathode voltage control part (10) charges a capacitor with a constant current and controls the charging time period, thereby deciding the cathode voltage. The gate electrode driving part (12) uses a complement connection to perform an ON/OFF control of the gate electrode.</p>
