PURPOSE: To make the long-time discharge possible with the brightness improved, by applying mutually-out-of-phase high-frequency voltages between AC-type electrodes of a cell with a dischargeable gas sealed between two AC-type electrodes with a dielectric coating and a DC-type electrode.

CONSTITUTION: Two AC-type electrodes 2a and 2b, which are formed on glass substrate 1 and covered with dielectric film 4, and DC-type electrode 3 formed on substrate 1 are arranged maintaining discharge space, and a dischargeable gas is sealed into the space. One discharge cell is formed of electrodes 2a and 2b, and 3, and adjacent electrodes 2a and 2b are applied with high-frequency voltages with phases made opposite to cause the discharge, thereby attaining the long-time and stable discharge with the brightness improved extremely