To obtain a half-tone display, the device disclosed employs a thin-film EL display panel and practices amplitude and pulse-width modulation wherein the amplitude and pulse-width of a pulse voltage applied to the thin-film EL display panel is varied according to video signals. In one preferred form thereof, a constant current amount or an enabling period of a constant current element provided within a discharge circuit is varied according to video signals, thereby controlling a pre-charge amplitude on the thin-film EL panel. The amount of discharging the pre-charge on the EL panel is under the control video signals. As a result, the brightness of the EL display panel corresponds to video signals.