An electroluminescent (EL) device achieves a significant increase in the
lifetime of EL light sources by using a driver having a standard DC-to-AC
inverter generating a high-frequency quasi-sinusoidal signal, and a
generator of low-frequency rectangular pulses. The inverter and the
generator are connected so that the quasi-sinusoidal signal is fed to the
EL light source in packets. The duration of a packet is equal to the
duration of the rectangular pulse. The duration of the rectangular pulses
and of the packets remains constant during the entire operating cycle of
the EL light source. The duration of intervals between rectangular pulses
and between packets is variable, causing changes in the duty cycle, and
is determined by the signal passing through a feedback circuit having an
EL light source, a photosensitive element, an amplifier, and an input of
the rectangular signal generator.