Electroluminescence
is the direct conversion of electric energy to light by a luminescent
material. Subject to the kind of electric input (AC or DC) and
the type of luminescent material used (organic, inorganic, powder,
polymer, thin film, etc.) there are several different kinds of
electroluminescence.
The
LumiFlux technology relates to alternating current driven, thick
film, inorganic electroluminescence (ACTFEL).
Electroluminescent
(EL) lamp (as used in this presentation/website) is a solid
state area light source. Light is generated by an electroluminescent
material (phosphor), powered by an alternating electric field.
The light emitting particle (phosphor) is sandwiched between two
electrodes, one of which is transparent. Voltage across the electrodes
generates an electric field exciting the phosphor particles to
emit light through the entire surface of the transparent electrode.
EL
lamps are thin, light-weight, cold, flexible, energy efficient,
and are the most useful uniform area light sources.
LumiFlux
EL lamps are constructed by depositing various layers in a
sandwich-like arrangement, including back electrode, ferroelectric,
phosphor, transparent electrode layers, all encapsulated in a
protective, transparent envelope with external electrode connections.
The layers are deposited using various polymer-based liquid inks.
The thickness of all the active layers is between 70-100 microns;
the total thickness of the lamps is less then 1 mm. The deposition
method is based on screen-printing; it is versatile enough to
create complex shapes, images, independently addressed sectors,
and colours.
Light-emitting
layer consist of electroluminescent phosphor particles dispersed
in a dielectric media (binder).
LumiFlux
EL lamps are powered by any variation between 30-200 V, 50-1000
Hz alternating current, preferably sinusoidal waveform (drive),
generally supplied through an inverter, from battery or main.
Drive
or driving parameters refers to AC voltage and frequency supplied
to the lamp.
Extra low voltage (ELV) drive means that the AC voltage
is below 50V.
Excessive drive: increasing the driving voltage above 140
V RMS or the frequency above 600 Hz. This drive results in accelerated
deterioration and lower brightness maintenance of the EL lamps.
The rate of deterioration, caused by the excessive drive is also
influenced by the lamps' construction and the efficiency.
Powering
EL lamps: In most cases the alternating current is supplied
to the EL lamps by an inverter.
The inverter (or driver) is powered either from a battery
or directly from the mains. For optimum operation the inverter
and the lamp should be matched: the inverter, during operation,
senses the deterioration of the lamp, and continuously increases
the voltage and/or frequency to maintain constant brightness.
The inverters can also operate the lamps in flashing mode.
Performance
characteristics of an EL lamp:
