<s>
A	O
membrane	B-Device
keyboard	I-Device
is	O
a	O
computer	B-Device
keyboard	I-Device
whose	O
"	O
keys	O
"	O
are	O
not	O
separate	O
,	O
moving	O
parts	O
,	O
as	O
with	O
the	O
majority	O
of	O
other	O
keyboards	B-Device
,	O
but	O
rather	O
are	O
pressure	O
pads	O
that	O
have	O
only	O
outlines	O
and	O
symbols	O
printed	O
on	O
a	O
flat	O
,	O
flexible	O
surface	O
.	O
</s>
<s>
Very	O
little	O
,	O
if	O
any	O
,	O
tactile	O
feedback	O
is	O
felt	O
when	O
using	O
such	O
a	O
keyboard	B-Device
.	O
</s>
<s>
Membrane	B-Device
keyboards	I-Device
work	O
by	O
electrical	O
contact	O
between	O
the	O
keyboard	B-Device
surface	O
and	O
the	O
underlying	O
circuits	O
when	O
keytop	O
areas	O
are	O
pressed	O
.	O
</s>
<s>
The	O
keyboards	B-Device
are	O
quite	O
inexpensive	O
to	O
mass-produce	O
,	O
and	O
are	O
more	O
resistant	O
against	O
dirt	O
and	O
liquids	O
than	O
most	O
other	O
keyboards	B-Device
.	O
</s>
<s>
Chiclet	B-Device
keyboards	I-Device
were	O
a	O
slight	O
improvement	O
,	O
at	O
least	O
allowing	O
individual	O
keys	O
to	O
be	O
felt	O
to	O
some	O
extent	O
.	O
</s>
<s>
Aside	O
from	O
early	O
hobbyist/kit/home	O
computers	O
and	O
some	O
video	B-Device
game	I-Device
consoles	I-Device
,	O
membrane-based	O
QWERTY	O
keyboards	B-Device
are	O
used	O
in	O
some	O
industrial	O
computer	O
systems	O
,	O
and	O
are	O
also	O
found	O
as	O
portable	O
,	O
even	O
"	O
rollable-collapsible	O
"	O
designs	O
for	O
PDAs	B-Application
and	O
other	O
pocket	O
computing	O
devices	O
.	O
</s>
<s>
Smaller	O
,	O
specialised	O
membrane	B-Device
keyboards	I-Device
,	O
typically	O
numeric-and-a-few-control-keys	O
only	O
,	O
have	O
been	O
used	O
in	O
access	O
control	O
systems	O
(	O
for	O
buildings	O
and	O
restricted	O
areas	O
)	O
,	O
simple	O
handheld	O
calculators	O
,	O
domestic	O
remote	B-Protocol
control	I-Protocol
keypads	O
,	O
microwave	O
ovens	O
,	O
and	O
other	O
similar	O
devices	O
where	O
the	O
amount	O
of	O
typing	O
is	O
relatively	O
small	O
or	O
infrequent	O
,	O
such	O
as	O
cell	O
phones	O
.	O
</s>
<s>
Modern	O
PC	B-Device
keyboards	I-Device
are	O
essentially	O
a	O
membrane	B-Device
keyboard	I-Device
mechanism	O
covered	O
with	O
an	O
array	O
of	O
dome	O
switches	O
which	O
give	O
positive	O
tactile	O
feedback	O
.	O
</s>
<s>
thumb|	O
Cross-section	O
diagram	O
of	O
a	O
typical	O
membrane	B-Device
keyboard	I-Device
.	O
</s>
<s>
The	O
membrane	B-Device
keyboard	I-Device
consists	O
of	O
three	O
layers	O
;	O
two	O
of	O
these	O
are	O
membrane	O
layers	O
containing	O
conductive	O
traces	O
.	O
</s>
<s>
Membrane	B-Device
keyboards	I-Device
are	O
widely	O
used	O
in	O
consumer	O
electronics	O
,	O
industrial	O
,	O
commercial	O
,	O
scientific	O
and	O
military	O
equipment	O
.	O
</s>
