Abstract: During a normal operation, alternating drive voltage to be applied between a pair of electrodes provided to face an outer surface of a bottom part of a gas discharge light emitting tube is switched to a voltage value V2 lower than a voltage value V1 at the time of starting lighting. Further, the alternating drive voltage to be applied during the normal discharge operation is intermittently applied in a predetermined cycle and duty ratio to enable adjustment of light emission intensity.

Abstract: A gas discharge device includes a thin glass tube filled with a discharge gas; a pair of first and second long electrodes extending toward either side along a longitudinal direction with a discharge gap interposed therebetween are provided outside of a back side flat surface of a thin glass tube; and a ultraviolet phosphor layer formed on an inner surface at the back side flat surface, the thin glass tube filled with a discharge gas having a front side flat surface and the back side flat surface facing each other on a transverse section, wherein, starting with trigger discharge that is initially generated in the discharge gap as a result of a voltage increase when a voltage with a sine waveform or an inclined waveform is applied between both electrodes, the discharge gradually extends so as to move in the longitudinal direction of the electrodes.