<s>
A	O
frontlight	B-Device
is	O
a	O
means	O
of	O
illuminating	O
a	O
display	B-Device
device	I-Device
,	O
usually	O
a	O
liquid	B-Device
crystal	I-Device
display	I-Device
(	O
LCD	B-Device
)	O
,	O
which	O
would	O
otherwise	O
be	O
viewed	O
in	O
ambient	O
light	O
.	O
</s>
<s>
An	O
LCD	B-Device
presents	O
an	O
image	O
by	O
absorbing	O
some	O
light	O
passing	O
through	O
it	O
.	O
</s>
<s>
This	O
allows	O
LCDs	B-Device
to	O
operate	O
at	O
low	O
power	O
,	O
as	O
no	O
energy	O
needs	O
to	O
be	O
spent	O
generating	O
light	O
.	O
</s>
<s>
Many	O
battery-operated	O
electronic	O
devices	O
,	O
including	O
most	O
calculators	O
and	O
other	O
devices	O
use	O
unilluminated	O
LCDs	B-Device
.	O
</s>
<s>
An	O
unilluminated	O
LCD	B-Device
must	O
be	O
lit	O
from	O
the	O
front	O
.	O
</s>
<s>
To	O
use	O
ambient	O
light	O
,	O
the	O
liquid	B-Device
crystal	I-Device
itself	O
is	O
sandwiched	O
between	O
a	O
polarization	O
filter	O
and	O
a	O
reflective	O
surface	O
.	O
</s>
<s>
Most	O
often	O
a	O
light	O
source	O
is	O
placed	O
around	O
the	O
perimeter	B-Application
of	O
the	O
LCD	B-Device
.	O
</s>
<s>
Frontlights	B-Device
are	O
relatively	O
uncommon	O
.	O
</s>
<s>
The	O
monochromatic	O
light	O
from	O
an	O
electroluminescent	O
source	O
does	O
not	O
work	O
well	O
with	O
color	B-Device
displays	I-Device
,	O
however	O
.	O
</s>
<s>
An	O
incandescent	O
frontlight	B-Device
was	O
therefore	O
a	O
popular	O
accessory	O
for	O
the	O
Nintendo	B-Device
Game	I-Device
Boy	I-Device
Color	I-Device
.	O
</s>
