How the Wacom cordless,
batteryless pen works
The Wacom stylus looks and feels like a
pen yet contains no batteries or magnets.
Instead it takes advantage of electromagnetic
resonance technology developed
by Wacom Co. Ltd. in which radio waves
are sent to the stylus and returned for
position analysis. In operation, a grid of
wires below the screen alternates between
transmit and receive modes about every
20 microseconds.
The electro-magnetic signal stimulates
oscillation in the coil-and-capacitor resonant
circuit in the pen. The resonant circuit
in the pen’s tip supplies the power and
serves as transmitter too. The received
signal goes through the modulator to the
chip. The information of the pressure sensor
(capacity) and of the side switch are
going to the chip first. The Tool ID is then
added and both are sent back to the
modulator which in turn sends a signal to
the resonant circuit in the tip. The tablet
picks up the information in the pen’s tip in
order to determine position and other
information like pressure and Tool ID.
Since the grid provides the power
to the pen through resonant coupling,
no batteries are required. Thus
there are no consumables inside the pen
that will run down and need to be replaced
or that would make the pen topheavy. |
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A simple analogy for this patented technology
is that of a piano tuner using a
tuning fork to tune a piano. As the
tuning fork is brought into proximity of
the appropriate vibrating pianostring (if
the fork is of the same frequency) it will
begin to borrow energy from the vibrating
sting and resonate, generating a
tone. In much the same way, as the
Wacom pen comes close to the tablet
surface, it begins to resonate, generating
its own frequency back to the tablet.
When it hears the pen, it tracks the
pen's location with unprecedented
accuracy. The tablet then sends location,
pressure and tilt information to the computer
along with a signal indicating
whether the pen point or the eraser is
being used.
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