Logitech International S.A.
Electromagnetic pulse driver

Abstract:

A driver circuit is provided to connect a charged capacitor through a switch to the inductive windings of an electromagnet for a haptic feedback application. A feedback circuit provides an indication of the current supplied. When the current reaches a desired level, the current is cut off, rather than being controlled. The cutoff level can be slightly below the desired level to allow the desired level to be reached with overshoot. A diode is provided in parallel with the electromagnet winding when the current is shut off, providing a recirculation path that prevents the current from being discharged, thereby dissipating less energy than classical solutions.