How Wacom Pens work – EMR (Electro-magnetic Resonance) Explained

wacom pro pen 3DThe stylus is getting more and more popular these days. Apple, Samsung, Microsoft, Wacom everyone has their own stylus.

Batteryless pens have been in the spotlight these days with some people calling them a work of magic. We, being a strong believer in science dug deep to reveal the technology working inside. Well, what we have been able to find is nothing short of incredible but at the same time very easy to understand.

How Wacom pens work – Overview

how wacom pens work infographic

We already know that Wacom pens are considered one of the most advanced and accurate styles in the market. They don’t have a conventional source of power (battery) inside, but like every electronic device, it needs the power to work. The question is where does the power come from.

The pen gets its power using EMR (Electro-Magnetic Resonance) which is a fancy way of saying “it receives its power from the tablet”.

The tablet has a set of coils throughout the surface which generates an electromagnetic field. These electromagnetic fields are picked up by the pen when it approaches near the surface. The pen has coils of copper wires which transform the electromagnetic waves into electrical energy. The electrical energy is then used to generate pressure, tilt and other data. The generated data goes back to the coil and gets converted into waves which get picked up by the tablet.

The technology behind – Full breakdown

If we take a closer look at the tablet we would find a printed circuit board behind the drawing surface. This circuit board has the horizontal and vertical loop of copper wires running throughout the board.

These wires generate a low power, low range electromagnetic waves. These waves constantly look for nearby devices to interact with.

When a pen/stylus approaches the board it picks up the electromagnetic signal through the copper coil at its tip.

Then there is the two-step process involved. In step one, the pen receives the electromagnetic waves through the coil and converts it into electrical energy. The generated power is stored in capacitors.

In step two, the pen uses the power to calculate the pressure, tilt and button press data and sends it to the coil.

copper coil in stylusNow the coil converts the received data into electromagnetic signals and transmits it to the board. The tablet now goes into receiving mode and looks for an incoming signal. On getting the signal it tracks the location and combines it with the pen data. The data is then amplified through an onboard circuit and sent to the computer.

This whole process of sending and receiving energy and data happens in less than 7 milliseconds. The process is repeated over and over again to track the total path and pressure ranges.

Advantages of passive (batteryless) pens over the battery powered stylus

Maintainance free

By maintenance free, we mean that the passive pen does not need to be charged at repeated intervals. They can be used whenever you want and for whatever period of time, continuously.

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Less susceptible to damage

These pens do not have any moving parts which flex over time and damages the circuit. The battery inside most of the pens degrade over time and heavily influence their usability. The batteryless pens prevent all these issues by excluding the battery itself.

Better Accuracy

The EMR technology gives overall a better performance due to a very high number of data points and fast communication. Its output is more consistent and smooth. The pressure curve is accurate even at the lowest levels giving near perfect readings and output.

Shubham Singh

Shubham Singh is an Adobe Certified graphic designer and 3D artist and has worked on a variety of company, contractual and freelance projects.

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