Open-Source Electromagnetic Resonance Tablet Successfully Launched

Revolutionizing Drawing Tablets

Drawing tablets have been a favorite accessory for artists since the 1980s. If you have ever wondered how a drawing tablet works and if you could build one, look no further! [Yukidama] has demonstrated how to create an open-source electromagnetic resonance (EMR) drawing tablet.

The principle behind EMR tablets is quite straightforward. A coil within the tablet oscillates between 400 kHz and 600 kHz, inducing a current in a stylus coil at its resonant frequency. This, in turn, generates an increase in voltage in the tablet, which corresponds to the resonant frequency of the stylus. To detect pressure, a simple circuit in the stylus can modify its resonant frequency, which is also detected by the tablet.

The tablet's input button operates in a similar manner! However, this is just one dimension. To capture two dimensions, two coil arrays are needed: one for the horizontal axis and one for the vertical axis. The driving circuit scans the matrix and captures each coil at an arbitrary speed.

In the end, [Yukidama] successfully demonstrated refinement through the design of a driver board, intended to power a flexible circuit with coils. This is now positioned behind the screen of a Panasonic RZ series laptop, effectively transforming the device into a highly efficient drawing tablet!

If tablets are not your style, take a look at this drawing stylus. Thanks to [anfractuosity] for the insights!