Implementation of input functionality using energy source for further miniaturization of small devices

Miniaturization is one of the keys to realizing ubiquitous and wearable devices with greatly improved practicality. The barriers to further miniaturization include energy sources and the systems for user input/output. Completely removing direct physical interaction with the user and conducting all interaction through intermediary devices is an easy approach to further device miniaturization. Direct interaction, however, provides an alternative, redundant, and sometimes quite intuitive means of device control, and so study of its implementation is warranted. This paper explores how to integrate energy supplies with input systems while ensuring miniaturization. The proposed technique detects the deliberately sequenced interruption of the energy supply, forced by the user, as a command. It is implemented on prototypes with a battery and a PV (photovoltaic) module, and finally, applied to active tags as a typical example. The technique is practical and promising for further device miniaturization.