Video explanation
A cutaway links key travel to magnetic-field readings as a magnet approaches a sensor. A spring returns the key, showing how a keypress can be measured continuously rather than as a simple on/off event.
Measuring travel magnetically
Changing the magnet–sensor position changes the measured field; calibration maps that reading to key travel.
Configurable actuation
Continuous position readings allow software-selected thresholds; accuracy depends on the sensor, mechanics and calibration.
Spring return
The spring supplies return force while the magnet and sensor detect position. Demo readings do not establish real keyboard performance.