<s>
In	O
display	B-Device
technology	I-Device
parlance	O
,	O
viewing	B-General_Concept
angle	I-General_Concept
is	O
the	O
angle	O
at	O
which	O
a	O
display	O
can	O
be	O
viewed	O
with	O
acceptable	O
visual	O
performance	O
.	O
</s>
<s>
In	O
a	O
technical	O
context	O
,	O
the	O
angular	O
range	O
is	O
called	O
viewing	B-Device
cone	I-Device
defined	O
by	O
a	O
multitude	O
of	O
viewing	B-Device
directions	I-Device
.	O
</s>
<s>
The	O
viewing	B-General_Concept
angle	I-General_Concept
can	O
be	O
an	O
angular	O
range	O
over	O
which	O
the	O
display	O
view	O
is	O
acceptable	O
,	O
or	O
it	O
can	O
be	O
the	O
angle	O
of	O
generally	O
acceptable	O
viewing	O
,	O
such	O
as	O
a	O
twelve	O
o'clock	O
viewing	B-General_Concept
angle	I-General_Concept
for	O
a	O
display	O
optimized	O
or	O
viewing	O
from	O
the	O
top	O
.	O
</s>
<s>
The	O
image	O
may	O
seem	O
garbled	O
,	O
poorly	O
saturated	O
,	O
of	O
poor	O
contrast	O
,	O
blurry	O
,	O
or	O
too	O
faint	O
outside	O
the	O
stated	O
viewing	B-General_Concept
angle	I-General_Concept
range	O
,	O
the	O
exact	O
mode	O
of	O
"	O
failure	O
"	O
depends	O
on	O
the	O
display	O
type	O
in	O
question	O
.	O
</s>
<s>
Many	O
manufacturers	O
of	O
projection	O
screens	O
thus	O
define	O
the	O
viewing	B-General_Concept
angle	I-General_Concept
as	O
the	O
angle	O
at	O
which	O
the	O
luminance	O
of	O
the	O
image	O
is	O
exactly	O
half	O
of	O
the	O
maximum	O
.	O
</s>
<s>
With	O
LCD	B-Device
screens	I-Device
,	O
some	O
manufacturers	O
have	O
opted	O
to	O
measure	O
the	O
contrast	O
ratio	O
,	O
and	O
report	O
the	O
viewing	B-General_Concept
angle	I-General_Concept
as	O
the	O
angle	O
where	O
the	O
contrast	O
ratio	O
exceeds	O
5:1	O
or	O
10:1	O
,	O
giving	O
minimally	O
acceptable	O
viewing	O
conditions	O
.	O
</s>
<s>
The	O
viewing	B-General_Concept
angle	I-General_Concept
is	O
measured	O
from	O
one	O
direction	O
to	O
the	O
opposite	O
,	O
giving	O
a	O
maximum	O
of	O
180°	O
for	O
a	O
flat	O
,	O
one-sided	O
screen	O
.	O
</s>
<s>
A	O
display	O
may	O
exhibit	O
different	O
behaviour	O
in	O
horizontal	O
and	O
vertical	O
axes	O
,	O
requiring	O
users	O
and	O
manufacturers	O
to	O
specify	O
maximum	O
usable	O
viewing	B-General_Concept
angles	I-General_Concept
in	O
both	O
directions	O
.	O
</s>
<s>
Usually	O
the	O
screens	O
are	O
designed	O
to	O
facilitate	O
greater	O
viewing	B-General_Concept
angle	I-General_Concept
in	O
horizontal	O
level	O
,	O
and	O
smaller	O
angle	O
in	O
the	O
vertical	O
level	O
,	O
should	O
the	O
two	O
of	O
them	O
be	O
different	O
in	O
magnitude	O
.	O
</s>
<s>
The	O
viewing	B-General_Concept
angle	I-General_Concept
for	O
some	O
displays	O
are	O
specified	O
in	O
only	O
a	O
general	O
direction	O
,	O
such	O
as	O
6	O
o'clock	O
or	O
12	O
o'clock	O
.	O
</s>
<s>
Early	O
LCDs	B-Device
had	O
strikingly	O
narrow	O
viewing	B-Device
cones	I-Device
,	O
a	O
situation	O
that	O
has	O
been	O
improved	O
with	O
current	O
technology	O
.	O
</s>
<s>
Narrow	O
viewing	B-Device
cones	I-Device
of	O
some	O
types	O
of	O
displays	O
have	O
also	O
been	O
used	O
to	O
bring	O
a	O
measure	O
of	O
security	O
in	O
businesses	O
,	O
where	O
employees	O
handle	O
private	O
information	O
in	O
the	O
presence	O
of	O
customers	O
,	O
banks	O
being	O
one	O
example	O
.	O
</s>
