<s>
A	O
projection	B-Device
keyboard	I-Device
is	O
a	O
form	O
of	O
computer	B-Device
input	I-Device
device	I-Device
whereby	O
the	O
image	O
of	O
a	O
virtual	B-Device
keyboard	I-Device
is	O
projected	O
onto	O
a	O
surface	O
:	O
when	O
a	O
user	O
touches	O
the	O
surface	O
covered	O
by	O
an	O
image	O
of	O
a	O
key	O
,	O
the	O
device	O
records	O
the	O
corresponding	O
keystroke	O
.	O
</s>
<s>
Some	O
connect	O
to	O
Bluetooth	B-Protocol
devices	O
,	O
including	O
many	O
of	O
the	O
latest	O
smartphone	O
,	O
tablet	O
,	O
and	O
mini-PC	O
devices	O
with	O
Android	O
,	O
iOS	O
or	O
Windows	O
operating	O
system	O
.	O
</s>
<s>
An	O
optical	O
virtual	B-Device
keyboard	I-Device
was	O
invented	O
and	O
patented	O
by	O
IBM	O
engineers	O
in	O
1992	O
.	O
</s>
<s>
It	O
optically	O
detects	O
and	O
analyses	O
human	O
hand	O
and	O
finger	O
motions	O
and	O
interprets	O
them	O
as	O
operations	O
on	O
a	O
physically	O
non-existent	O
input	B-Device
device	I-Device
like	O
a	O
surface	O
with	O
painted	O
or	O
projected	O
keys	O
.	O
</s>
<s>
In	O
that	O
way	O
,	O
it	O
can	O
emulate	O
unlimited	O
types	O
of	O
manually	O
operated	O
input	B-Device
devices	I-Device
(	O
such	O
as	O
a	O
mouse	O
,	O
keyboard	O
,	O
and	O
other	O
devices	O
)	O
.	O
</s>
<s>
In	O
2002	O
,	O
start-up	O
company	O
Canesta	O
developed	O
a	O
projection	B-Device
keyboard	I-Device
using	O
their	O
proprietary	O
"	O
electronic	O
perception	O
technology.	O
"	O
</s>
<s>
A	O
proposed	O
system	O
called	O
the	O
P-ISM	O
combines	O
the	O
technology	O
with	O
a	O
small	O
video	B-Device
projector	I-Device
to	O
create	O
a	O
portable	O
computer	O
the	O
size	O
of	O
a	O
fountain	O
pen	O
.	O
</s>
<s>
A	O
laser	B-General_Concept
or	O
beamer	B-Device
projects	O
visible	O
virtual	B-Device
keyboard	I-Device
onto	O
level	O
surface	O
.	O
</s>
<s>
It	O
is	O
a	O
modern	O
input	B-Device
device	I-Device
.	O
</s>
<s>
A	O
sensor	B-Application
or	O
camera	O
in	O
the	O
projector	O
picks	O
up	O
finger	O
movements	O
.	O
</s>
<s>
Some	O
devices	O
project	O
a	O
second	O
(	O
invisible	O
infrared	O
)	O
beam	O
above	O
the	O
virtual	B-Device
keyboard	I-Device
.	O
</s>
<s>
The	O
user	O
's	O
finger	O
makes	O
a	O
keystroke	O
on	O
the	O
virtual	B-Device
keyboard	I-Device
.	O
</s>
<s>
The	O
sensor	B-Application
chip	O
determines	O
where	O
infrared	O
beam	O
was	O
broken	O
.	O
</s>
<s>
The	O
projection	O
is	O
realized	O
in	O
four	O
main	O
steps	O
and	O
via	O
three	O
modules	B-Architecture
:	O
projection	O
module	B-Architecture
,	O
sensor	B-Application
module	B-Architecture
and	O
illumination	O
module	B-Architecture
.	O
</s>
<s>
The	O
main	O
devices	O
and	O
technologies	O
used	O
to	O
project	O
the	O
image	O
are	O
a	O
diffractive	O
optical	O
element	O
,	O
red	O
laser	B-General_Concept
diode	O
,	O
CMOS	B-Device
sensor	B-Application
chip	O
and	O
an	O
infrared	O
(	O
IR	O
)	O
laser	B-General_Concept
diode	O
.	O
</s>
<s>
A	O
template	O
produced	O
by	O
a	O
specially	O
designed	O
and	O
highly	O
efficient	O
projection	O
element	O
with	O
a	O
red	O
diode	O
laser	B-General_Concept
is	O
projected	O
onto	O
the	O
adjacent	O
interface	O
surface	O
.	O
</s>
<s>
When	O
a	O
key	O
position	O
is	O
touched	O
on	O
the	O
surface	O
interface	O
,	O
the	O
light	O
is	O
reflected	O
from	O
the	O
infra-red	O
plane	O
in	O
the	O
vicinity	O
of	O
the	O
key	O
and	O
directed	O
towards	O
the	O
sensor	B-Application
module	B-Architecture
.	O
</s>
<s>
The	O
reflected	O
light	O
user	O
interactions	O
with	O
the	O
interface	O
surface	O
is	O
passed	O
through	O
an	O
infra-red	O
filter	O
and	O
imaged	O
on	O
to	O
a	O
CMOS	B-Device
image	O
sensor	B-Application
in	O
the	O
sensor	B-Application
module	B-Architecture
.	O
</s>
<s>
The	O
sensor	B-Application
chip	O
has	O
a	O
custom	O
hardware	O
embedded	O
such	O
as	O
the	O
Virtual	O
Interface	O
Processing	O
Core	O
and	O
it	O
is	O
capable	O
of	O
making	O
a	O
real-time	O
determination	O
of	O
the	O
location	O
from	O
where	O
the	O
light	O
was	O
reflected	O
.	O
</s>
<s>
The	O
micro-controller	B-Architecture
in	O
the	O
sensor	B-Application
module	B-Architecture
receives	O
the	O
positional	O
information	O
corresponding	O
to	O
the	O
light	O
flashes	O
from	O
the	O
sensor	B-Application
processing	O
core	O
,	O
interprets	O
the	O
events	O
and	O
then	O
communicates	O
them	O
through	O
the	O
appropriate	O
interface	O
to	O
external	O
devices	O
.	O
</s>
<s>
By	O
events	O
it	O
is	O
understood	O
any	O
key	O
stroke	O
,	O
mouse	O
or	O
touchpad	B-Application
control	O
.	O
</s>
<s>
Most	O
projection	B-Device
keyboards	I-Device
use	O
a	O
red	O
diode	O
laser	B-General_Concept
as	O
a	O
light	O
source	O
and	O
may	O
project	O
a	O
full	O
size	O
QWERTY	O
keyboard	O
.	O
</s>
<s>
The	O
projected	O
keyboard	O
size	O
is	O
usually	O
295mm	O
x	O
95mm	O
and	O
it	O
is	O
projected	O
at	O
a	O
distance	O
of	O
60mm	O
from	O
the	O
virtual	B-Device
keyboard	I-Device
unit	O
.	O
</s>
<s>
The	O
projection	B-Device
keyboard	I-Device
detects	O
up	O
to	O
400	O
characters	O
per	O
minute	O
.	O
</s>
<s>
Projection	B-Device
keyboards	I-Device
connect	O
to	O
the	O
computer	O
either	O
through	O
Bluetooth	B-Protocol
or	O
USB	B-Protocol
.	O
</s>
<s>
Bluetooth	B-Protocol
dongle	O
technology	O
enables	O
the	O
projection	B-Device
keyboard	I-Device
for	O
point	O
to	O
multi-point	O
connectivity	O
with	O
other	O
Bluetooth	B-Protocol
devices	O
,	O
such	O
as	O
PCs	O
,	O
PDAs	B-Application
and	O
mobile	O
phone	O
.	O
</s>
<s>
The	O
way	O
that	O
Bluetooth	B-Protocol
projection	B-Device
keyboards	I-Device
connect	O
to	O
devices	O
depends	O
on	O
the	O
specific	O
tablet	O
,	O
phone	O
or	O
computer	O
.	O
</s>
<s>
Apart	O
from	O
simply	O
being	O
used	O
to	O
type	O
,	O
some	O
laser	B-Device
keyboard	I-Device
systems	O
can	O
function	O
as	O
a	O
virtual	O
mouse	O
or	O
even	O
as	O
a	O
virtual	O
piano	O
,	O
such	O
as	O
the	O
crowd-funded	O
iKeybo	O
.	O
</s>
