<s>
A	O
see-through	B-Device
display	I-Device
or	O
transparent	B-Device
display	I-Device
is	O
an	O
electronic	O
display	O
that	O
allows	O
the	O
user	O
to	O
see	O
what	O
is	O
shown	O
on	O
the	O
screen	O
while	O
still	O
being	O
able	O
to	O
see	O
through	O
it	O
.	O
</s>
<s>
The	O
main	O
applications	O
of	O
this	O
type	O
of	O
display	O
are	O
in	O
head-up	B-Application
displays	I-Application
,	O
augmented	B-General_Concept
reality	I-General_Concept
systems	O
,	O
digital	O
signage	O
,	O
and	O
general	O
large-scale	O
spatial	O
light	O
modulation	O
.	O
</s>
<s>
Transparent	B-Device
displays	I-Device
embed	O
the	O
active	O
matrix	O
of	O
the	O
display	O
in	O
the	O
field	O
of	O
view	O
,	O
which	O
generally	O
allows	O
them	O
to	O
be	O
more	O
compact	O
than	O
combination-based	O
systems	O
.	O
</s>
<s>
Broadly	O
,	O
there	O
are	O
two	O
types	O
of	O
underlying	O
transparent	B-Device
display	I-Device
technology	O
,	O
absorptive	O
(	O
chiefly	O
LCDs	B-Device
)	O
and	O
emissive	O
(	O
chiefly	O
electroluminescent	O
,	O
including	O
LEDs	O
and	O
"	O
high-field	O
"	O
emitters	O
)	O
.	O
</s>
<s>
The	O
development	O
of	O
practical	O
transparent	B-Device
displays	I-Device
accelerated	O
rapidly	O
around	O
the	O
end	O
of	O
first	O
decade	O
of	O
the	O
21st	O
century	O
.	O
</s>
<s>
An	O
early	O
commercial	O
transparent	B-Device
display	I-Device
was	O
the	O
Sony	O
Ericsson	O
Xperia	O
Pureness	O
released	O
in	O
2009	O
,	O
although	O
it	O
did	O
not	O
succeed	O
in	O
the	O
market	O
due	O
to	O
the	O
screen	O
not	O
being	O
visible	O
outside	O
or	O
in	O
brightly	O
lit	O
rooms	O
.	O
</s>
<s>
Samsung	B-Application
released	O
their	O
first	O
transparent	O
LCD	B-Device
in	O
late	O
2011	O
,	O
and	O
Planar	O
published	O
a	O
report	O
on	O
a	O
prototype	O
electroluminescent	O
transparent	B-Device
display	I-Device
in	O
2012	O
.	O
</s>
<s>
Not	O
long	O
after	O
,	O
UK-based	O
Crystal	O
Display	O
Systems	O
began	O
to	O
sell	O
transparent	O
LCDs	B-Device
remanufactured	O
from	O
conventional	O
LCD	B-Device
displays	I-Device
.	O
</s>
<s>
LG	O
demonstrated	O
a	O
transparent	O
LCD	B-Device
in	O
2015	O
.	O
</s>
<s>
In	O
the	O
later	O
part	O
of	O
the	O
2010s	O
,	O
transparent	O
OLEDs	B-Device
started	O
to	O
appear	O
.	O
</s>
<s>
LG	O
,	O
Prodisplay	O
,	O
and	O
taptl	O
,	O
for	O
example	O
,	O
use	O
conventional	O
LCD	B-Device
technology	O
.	O
</s>
<s>
LG	O
also	O
uses	O
OLED	B-Device
technology	O
.	O
</s>
<s>
LUMINEQ	O
transparent	B-Device
displays	I-Device
manufactured	O
by	O
Beneq	O
are	O
Thin	O
Film	O
Electroluminescent	O
Displays	O
enabled	O
by	O
Atomic	O
layer	O
deposition	O
(	O
ALD	O
)	O
.	O
</s>
<s>
This	O
display	O
technology	O
was	O
used	O
by	O
Valtra	O
in	O
2017	O
to	O
develop	O
its	O
SmartGlass	O
Head-Up	B-Application
Display	I-Application
on	O
tractors	O
.	O
</s>
<s>
Samsung	B-Application
and	O
Planar	O
Systems	O
previously	O
made	O
transparent	O
OLED	B-Device
displays	I-Device
but	O
discontinued	O
them	O
in	O
2016	O
.	O
</s>
<s>
Prodisplay	O
used	O
both	O
OLED	B-Device
and	O
LCD	B-Device
technology	O
,	O
but	O
no	O
longer	O
makes	O
transparent	O
OLED	B-Device
displays	I-Device
.	O
</s>
<s>
There	O
are	O
two	O
major	O
see-through	B-Device
display	I-Device
technologies	O
,	O
LCD	B-Device
and	O
LED	O
.	O
</s>
<s>
The	O
LED	O
technology	O
is	O
older	O
and	O
emitted	O
a	O
red	O
color	O
,	O
OLED	B-Device
is	O
newer	O
than	O
both	O
using	O
an	O
organic	O
substance	O
.	O
</s>
<s>
though	O
OLED	B-Device
see-through	B-Device
displays	I-Device
are	O
becoming	O
more	O
widely	O
available	O
.	O
</s>
<s>
Both	O
technologies	O
are	O
largely	O
derivative	O
from	O
conventional	O
display	O
systems	O
,	O
but	O
in	O
see-through	B-Device
displays	I-Device
,	O
the	O
difference	O
between	O
the	O
absorptive	O
nature	O
of	O
the	O
LCD	B-Device
and	O
emissive	O
nature	O
of	O
the	O
OLED	B-Device
gives	O
them	O
very	O
different	O
visual	O
appearances	O
.	O
</s>
<s>
LCD	B-Device
systems	O
impose	O
a	O
pattern	O
of	O
shading	O
and	O
colours	O
on	O
the	O
background	O
seen	O
through	O
the	O
display	O
,	O
while	O
OLED	B-Device
systems	O
impose	O
a	O
glowing	O
image	O
pattern	O
on	O
the	O
background	O
.	O
</s>
<s>
The	O
most	O
common	O
use	O
of	O
see-through	B-Device
displays	I-Device
is	O
the	O
Pepper	O
's	O
ghost	O
illusion	O
,	O
using	O
a	O
see	O
through	O
mirror	O
and	O
a	O
high-brightness	O
LCD	B-Device
display	I-Device
.	O
</s>
<s>
An	O
LCD	B-Device
panel	I-Device
can	O
be	O
made	O
"	O
see-through	O
"	O
without	O
applied	O
voltage	O
when	O
a	O
twisted	O
nematic	O
LCD	B-Device
is	O
fitted	O
with	O
crossed	O
polarizers	O
.	O
</s>
<s>
Conventional	O
LCDs	B-Device
have	O
relatively	O
low	O
transmission	O
efficiency	O
due	O
to	O
the	O
use	O
of	O
polarizers	O
so	O
that	O
they	O
tend	O
to	O
appear	O
somewhat	O
dim	O
against	O
natural	O
light	O
.	O
</s>
<s>
Unlike	O
LED	O
see-through	B-Device
displays	I-Device
,	O
LCD	B-Device
see-throughs	O
do	O
not	O
produce	O
their	O
own	O
light	O
but	O
only	O
modulate	O
incoming	O
light	O
.	O
</s>
<s>
LCDs	B-Device
intended	O
specifically	O
for	O
see-through	B-Device
displays	I-Device
are	O
usually	O
designed	O
to	O
have	O
improved	O
transmission	O
efficiency	O
.	O
</s>
<s>
Small	O
scale	O
see-through	O
LCDs	B-Device
have	O
been	O
commercially	O
available	O
for	O
some	O
time	O
,	O
but	O
only	O
recently	O
have	O
vendors	O
begun	O
to	O
offer	O
units	O
with	O
sizes	O
comparable	O
to	O
LCD	B-Device
televisions	O
and	O
displays	O
.	O
</s>
<s>
Samsung	B-Application
released	O
a	O
specifically	O
see-through	O
designed	O
22-inch	O
panel	O
in	O
2011	O
.	O
</s>
<s>
As	O
of	O
2016	O
,	O
they	O
were	O
being	O
produced	O
by	O
Samsung	B-Application
,	O
LG	O
,	O
and	O
MMT	O
,	O
with	O
a	O
number	O
of	O
vendors	O
offering	O
products	O
based	O
on	O
OEM	O
systems	O
from	O
these	O
manufacturers	O
.	O
</s>
<s>
LCD	B-Device
displays	I-Device
often	O
also	O
require	O
removing	O
a	O
diffuser	O
layer	O
to	O
adapt	O
them	O
for	O
use	O
as	O
transparent	B-Device
displays	I-Device
.	O
</s>
<s>
The	O
key	O
limitation	O
to	O
see-through	O
LCD	B-Device
efficiency	O
is	O
its	O
linear	O
polarizing	O
filters	O
.	O
</s>
<s>
In	O
LCDs	B-Device
,	O
light	O
has	O
to	O
pass	O
two	O
linear	O
polarizers	O
,	O
either	O
in	O
the	O
crossed	O
or	O
parallel-aligned	O
configuration	O
.	O
</s>
<s>
Both	O
inorganic	O
and	O
organic	O
(	O
OLED	B-Device
)	O
LEDs	O
have	O
been	O
used	O
for	O
this	O
purpose	O
.	O
</s>
<s>
The	O
more	O
flexible	O
(	O
literally	O
and	O
figuratively	O
)	O
OLEDs	B-Device
have	O
generated	O
more	O
interest	O
for	O
this	O
application	O
,	O
though	O
as	O
of	O
July	O
2016	O
the	O
only	O
commercial	O
manufacturer	O
Samsung	B-Application
announced	O
that	O
the	O
product	O
would	O
be	O
discontinued	O
.	O
</s>
<s>
OLEDs	B-Device
consist	O
of	O
an	O
emissive	O
and	O
conductive	O
layer	O
.	O
</s>
<s>
This	O
is	O
different	O
from	O
LCDs	B-Device
in	O
that	O
OLEDs	B-Device
produce	O
their	O
own	O
light	O
,	O
which	O
produces	O
a	O
markedly	O
different	O
visual	O
effect	O
with	O
a	O
see-through	B-Device
display	I-Device
.	O
</s>
<s>
OLED	B-Device
transparent	B-Device
displays	I-Device
generate	O
their	O
own	O
light	O
,	O
but	O
can	O
not	O
show	O
black	O
;	O
this	O
can	O
be	O
solved	O
by	O
the	O
addition	O
of	O
a	O
special	O
LCD	B-Device
layer	O
.	O
</s>
<s>
MIT	O
Researchers	O
developed	O
an	O
inexpensive	O
and	O
passive	O
transparent	B-Device
display	I-Device
system	O
that	O
uses	O
nano-particles	O
.	O
</s>
<s>
Unlike	O
transparent	O
LCDs	B-Device
and	O
OLEDs	B-Device
that	O
requires	O
integrated	O
electronic	O
modules	O
to	O
process	O
visual	O
signals	O
or	O
emit	O
their	O
own	O
light	O
,	O
a	O
passive	O
transparent	B-Device
display	I-Device
uses	O
a	O
projector	O
as	O
the	O
external	O
light	O
source	O
to	O
project	O
images	O
and	O
videos	O
onto	O
a	O
transparent	O
medium	O
embedded	O
with	O
resonance	O
nanoparticles	O
that	O
selectively	O
scatter	O
the	O
projected	O
light	O
.	O
</s>
<s>
This	O
approach	O
improves	O
the	O
deficiencies	O
observed	O
with	O
transparent	O
LCDs	B-Device
and	O
OLEDs	B-Device
,	O
such	O
as	O
high	O
cost	O
,	O
difficulty	O
of	O
scaling	O
in	O
size	O
,	O
and	O
delicate	O
maintenance	O
.	O
</s>
<s>
Unlike	O
LCDs	B-Device
and	O
LEDs	O
using	O
organic	O
materials	O
that	O
will	O
be	O
effected	O
by	O
environments	O
,	O
TASEL	O
displays	O
are	O
inorganic	O
and	O
immune	O
to	O
environments	O
.	O
</s>
<s>
A	O
head-mounted	B-General_Concept
display	I-General_Concept
projects	O
images	O
onto	O
a	O
transparent	O
screen	O
,	O
allowing	O
its	O
user	O
to	O
see	O
through	O
the	O
display	O
.	O
</s>
<s>
These	O
screens	O
can	O
be	O
used	O
for	O
augmented	B-General_Concept
reality	I-General_Concept
,	O
and	O
other	O
applications	O
such	O
as	O
shopping	O
displays	O
and	O
more	O
sophisticated	O
computer	O
screens	O
.	O
</s>
<s>
See-through	B-Device
displays	I-Device
based	O
on	O
OLED	B-Device
or	O
microLED	O
technology	O
may	O
display	O
black	O
through	O
the	O
addition	O
of	O
an	O
LCD	B-Device
,	O
as	O
they	O
cannot	O
do	O
it	O
on	O
their	O
own	O
.	O
</s>
<s>
This	O
is	O
because	O
,	O
in	O
OLED	B-Device
and	O
micro-LED	O
,	O
the	O
OFF	O
state	O
corresponds	O
to	O
black	O
(	O
or	O
in	O
this	O
case	O
,	O
transparent	O
since	O
there	O
is	O
no	O
black	O
background	O
)	O
and	O
the	O
ON	O
state	O
corresponds	O
to	O
white	O
;	O
this	O
is	O
because	O
OLED	B-Device
and	O
microLED	O
pixels	O
emit	O
their	O
own	O
light	O
.	O
</s>
<s>
See-through	O
LCDs	B-Device
cannot	O
display	O
whites	O
because	O
LCD	B-Device
pixels	O
do	O
not	O
emit	O
their	O
own	O
light	O
,	O
rather	O
they	O
selectively	O
block	O
light	O
from	O
a	O
white	O
backlight	O
,	O
although	O
this	O
could	O
theoretically	O
be	O
fixed	O
though	O
the	O
addition	O
of	O
a	O
transparent	O
monochrome	O
microLED	O
or	O
OLED	B-Device
display	I-Device
.	O
</s>
<s>
In	O
LCDs	B-Device
,	O
this	O
is	O
because	O
,	O
in	O
the	O
OFF	O
state	O
,	O
the	O
pixels	O
turn	O
off	O
,	O
allowing	O
light	O
from	O
a	O
backlight	O
to	O
pass	O
through	O
,	O
while	O
in	O
the	O
ON	O
state	O
,	O
the	O
pixels	O
turn	O
on	O
,	O
blocking	O
light	O
.	O
</s>
<s>
MIT	O
Researchers	O
were	O
working	O
on	O
creating	O
Transparent	B-Device
Displays	I-Device
inexpensively	O
using	O
nano-particles	O
.	O
</s>
<s>
Cell	O
phones	O
,	O
tablets	B-Device
and	O
other	O
devices	O
are	O
starting	O
to	O
use	O
this	O
technology	O
.	O
</s>
<s>
It	O
has	O
an	O
appealing	O
appearance	O
but	O
more	O
importantly	O
it	O
is	O
also	O
effective	O
for	O
augmented	B-General_Concept
reality	I-General_Concept
applications	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
you	O
look	O
through	O
a	O
tablet	B-Device
with	O
a	O
see-through	B-Device
display	I-Device
at	O
a	O
street	O
,	O
the	O
device	O
could	O
overlay	O
the	O
name	O
of	O
the	O
street	O
onto	O
the	O
screen	O
.	O
</s>
<s>
It	O
could	O
be	O
similar	O
to	O
Google	B-Application
street	I-Application
view	I-Application
,	O
except	O
in	O
real-time	O
.	O
</s>
<s>
For	O
example	O
,	O
Google	B-Application
Translate	I-Application
has	O
a	O
feature	O
that	O
allows	O
the	O
user	O
to	O
point	O
the	O
camera	O
at	O
a	O
sign	O
or	O
writing	O
in	O
another	O
language	O
and	O
it	O
automatically	O
displays	O
the	O
same	O
view	O
,	O
but	O
with	O
the	O
writing	O
in	O
the	O
language	O
of	O
your	O
choosing	O
.	O
</s>
<s>
This	O
could	O
be	O
possible	O
with	O
see-through	B-Device
displays	I-Device
as	O
well	O
.	O
</s>
<s>
A	O
device	O
using	O
a	O
transparent	B-Device
display	I-Device
will	O
have	O
much	O
higher	O
resolution	O
and	O
will	O
display	O
much	O
more	O
realistic	O
augmented	B-General_Concept
reality	I-General_Concept
than	O
video	O
augmented	B-General_Concept
reality	I-General_Concept
,	O
which	O
takes	O
video	O
,	O
adds	O
its	O
own	O
supplement	O
to	O
it	O
,	O
and	O
then	O
displays	O
that	O
onto	O
the	O
screen	O
.	O
</s>
<s>
The	O
Microsoft	B-General_Concept
HoloLens	I-General_Concept
is	O
an	O
application	O
of	O
this	O
idea	O
.	O
</s>
