<s>
A	O
barcode	B-Device
reader	I-Device
or	O
barcode	B-Device
scanner	I-Device
is	O
an	O
optical	B-Application
scanner	I-Application
that	O
can	O
read	O
printed	O
barcodes	O
,	O
decode	O
the	O
data	O
contained	O
in	O
the	O
barcode	O
to	O
a	O
computer	O
.	O
</s>
<s>
Additionally	O
,	O
nearly	O
all	O
barcode	B-Device
readers	I-Device
contain	O
decoder	O
circuitry	O
that	O
can	O
analyse	O
the	O
barcode	O
's	O
image	O
data	O
provided	O
by	O
the	O
sensor	O
and	O
send	O
the	O
barcode	O
's	O
content	O
to	O
the	O
scanner	O
's	O
output	O
port	O
.	O
</s>
<s>
Barcode	B-Device
readers	I-Device
can	O
be	O
differentiated	O
by	O
technologies	O
as	O
follows	O
:	O
</s>
<s>
In	O
both	O
pen	O
readers	O
and	O
laser	O
scanners	O
,	O
the	O
light	O
emitted	O
by	O
the	O
reader	O
is	O
rapidly	O
varied	O
in	O
brightness	O
with	O
a	O
data	O
pattern	O
and	O
the	O
photo-diode	O
receive	O
circuitry	O
is	O
designed	O
to	O
detect	O
only	O
signals	O
with	O
the	O
same	O
modulated	B-Application
pattern	O
.	O
</s>
<s>
Charge-coupled	B-Algorithm
device	I-Algorithm
(	O
CCD	O
)	O
readers	O
use	O
an	O
array	O
of	O
hundreds	O
of	O
tiny	O
light	O
sensors	O
lined	O
up	O
in	O
a	O
row	O
in	O
the	O
head	O
of	O
the	O
reader	O
.	O
</s>
<s>
Two-dimensional	O
imaging	B-General_Concept
scanners	I-General_Concept
are	O
a	O
newer	O
type	O
of	O
barcode	B-Device
reader	I-Device
.	O
</s>
<s>
Video	O
camera	O
readers	O
use	O
small	O
video	O
cameras	O
with	O
the	O
same	O
CCD	O
technology	O
as	O
in	O
a	O
CCD	O
barcode	B-Device
reader	I-Device
except	O
that	O
instead	O
of	O
having	O
a	O
single	O
row	O
of	O
sensors	O
,	O
a	O
video	O
camera	O
has	O
hundreds	O
of	O
rows	O
of	O
sensors	O
arranged	O
in	O
a	O
two	O
dimensional	O
array	O
so	O
that	O
they	O
can	O
generate	O
an	O
image	O
.	O
</s>
<s>
Omnidirectional	O
scanners	O
are	O
most	O
familiar	O
through	O
the	O
horizontal	O
scanners	O
in	O
supermarkets	O
,	O
where	O
packages	O
are	O
slid	O
over	O
a	O
glass	O
or	O
sapphire	B-Application
window	O
.	O
</s>
<s>
While	O
cell	O
phone	O
cameras	O
without	O
auto-focus	O
are	O
not	O
ideal	O
for	O
reading	O
some	O
common	O
barcode	O
formats	O
,	O
there	O
are	O
2D	O
barcodes	O
which	O
are	O
optimized	O
for	O
cell	O
phones	O
,	O
as	O
well	O
as	O
QR	O
Codes	O
(	O
Quick	O
Response	O
)	O
codes	O
and	O
Data	B-Algorithm
Matrix	I-Algorithm
codes	O
which	O
can	O
be	O
read	O
quickly	O
and	O
accurately	O
with	O
or	O
without	O
auto-focus	O
.	O
</s>
<s>
Music	O
:	O
CD	O
catalogs	O
–	O
playing	O
an	O
MP3	B-Application
when	O
scanned	O
.	O
</s>
<s>
Recent	O
versions	O
of	O
the	O
Android	B-Application
,	O
iOS	B-Application
,	O
and	O
Windows	B-Protocol
Phone	I-Protocol
mobile	O
phone	O
operating	O
systems	O
feature	O
QR	O
or	O
barcode	B-Device
scanners	I-Device
built	O
in	O
,	O
usually	O
accessible	O
from	O
their	O
respective	O
camera	O
application	O
.	O
</s>
<s>
Barcode	B-Device
readers	I-Device
can	O
be	O
distinguished	O
based	O
on	O
housing	O
design	O
as	O
follows	O
:	O
</s>
<s>
Handheld	B-Application
scanner	I-Application
with	O
a	O
handle	O
and	O
typically	O
a	O
trigger	O
button	O
for	O
switching	O
on	O
the	O
light	O
like	O
this	O
are	O
used	O
in	O
factory	O
and	O
farm	O
automation	O
for	O
quality	O
management	O
and	O
shipping	O
.	O
</s>
<s>
PDA	B-Application
scanner	O
(	O
or	O
Auto-ID	O
PDA	B-Application
)	O
a	O
PDA	B-Application
with	O
a	O
built-in	O
barcode	B-Device
reader	I-Device
or	O
attached	O
barcode	B-Device
scanner	I-Device
.	O
</s>
<s>
Cordless	O
scanner	O
(	O
or	O
Wireless	O
scanner	O
)	O
a	O
cordless	O
barcode	B-Device
scanner	I-Device
is	O
operated	O
by	O
a	O
battery	O
fit	O
inside	O
it	O
and	O
is	O
not	O
connected	O
to	O
the	O
electricity	O
mains	O
and	O
transfer	O
data	O
to	O
the	O
connected	O
device	O
like	O
PC	B-Device
.	O
</s>
<s>
Currently	O
any	O
camera	B-Device
equipped	I-Device
device	O
or	O
device	O
which	O
has	O
document	B-Application
scanner	I-Application
can	O
be	O
used	O
as	O
Barcode	B-Device
reader	I-Device
with	O
special	O
software	O
libraries	O
,	O
Barcode	B-Application
libraries	I-Application
.	O
</s>
<s>
In	O
this	O
way	O
,	O
combination	O
of	O
barcode	O
technology	O
and	O
barcode	B-Application
library	I-Application
allows	O
to	O
implement	O
with	O
low	O
cost	O
any	O
automatic	O
document	O
processing	O
OMR	O
,	O
package	O
tracking	O
application	O
or	O
even	O
augmented	O
reality	O
application	O
.	O
</s>
<s>
Early	O
barcode	B-Device
scanners	I-Device
,	O
of	O
all	O
formats	O
,	O
almost	O
universally	O
used	O
the	O
then-common	O
RS-232	O
serial	O
interface	O
.	O
</s>
<s>
As	O
the	O
PC	B-Device
with	O
its	O
various	O
standard	O
interfaces	O
evolved	O
,	O
it	O
became	O
ever	O
easier	O
to	O
connect	O
physical	O
hardware	O
to	O
it	O
.	O
</s>
<s>
The	O
early	O
"	O
keyboard	O
wedge	O
"	O
hardware	O
plugged	O
in	O
between	O
the	O
PS/2	B-Protocol
port	I-Protocol
and	O
the	O
keyboard	O
,	O
with	O
characters	O
from	O
the	O
barcode	B-Device
scanner	I-Device
appearing	O
exactly	O
as	O
if	O
they	O
had	O
been	O
typed	O
at	O
the	O
keyboard	O
.	O
</s>
<s>
Keyboard	O
wedges	O
plugging	O
in	O
via	O
the	O
USB	B-Protocol
interface	O
are	O
readily	O
available	O
.	O
</s>
<s>
The	O
"	O
keyboard	O
wedge	O
"	O
approach	O
makes	O
adding	O
things	O
such	O
as	O
barcode	B-Device
readers	I-Device
to	O
systems	O
simple	O
.	O
</s>
<s>
Subsequent	O
to	O
the	O
PS/2	B-Protocol
era	O
,	O
barcode	B-Device
readers	I-Device
began	O
to	O
use	O
USB	B-Protocol
ports	I-Protocol
rather	O
than	O
the	O
keyboard	O
port	O
,	O
this	O
being	O
more	O
convenient	O
.	O
</s>
<s>
Today	O
,	O
USB	B-Protocol
barcode	B-Device
readers	I-Device
are	O
"	O
plug	O
and	O
play	O
"	O
,	O
at	O
least	O
in	O
Windows	O
systems	O
.	O
</s>
<s>
In	O
many	O
cases	O
,	O
a	O
choice	O
of	O
USB	B-Protocol
interface	O
types	O
(	O
HID	O
,	O
CDC	O
)	O
are	O
provided	O
.	O
</s>
<s>
Some	O
modern	O
handheld	O
barcode	B-Device
readers	I-Device
can	O
be	O
operated	O
in	O
wireless	B-General_Concept
networks	I-General_Concept
according	O
to	O
IEEE	O
802.11g	O
(	O
WLAN	B-Architecture
)	O
or	O
IEEE	O
802.15.1	O
(	O
Bluetooth	B-Protocol
)	O
.	O
</s>
<s>
Some	O
barcode	B-Device
readers	I-Device
also	O
support	O
radio	O
frequencies	O
viz	O
.	O
</s>
