The present invention relates to a handwriting communication system, a handwriting input device and a handwriting display device used in the system, which can communicate by handwriting among a plurality of computers connected via a network. The detection circuit provides a first output signal to the wireless adapter upon detection of a triggering event, such as activation of a manual switch or detection of voltage of an audio output signal from a mobile communications device. In other embodiments, the knee may be active, whereby it can be used to assist with or completely control gait, as well as to generate electrical energy. Thermally isolating the power control device from at least a portion of the heat generated by the light source allows the power control device to be disposed relatively close to the light source without becoming overheated and damaged.