An underwater RF signal propagation path is created by utilizing a plurality of individual RF transceivers such as MEMS RF transceivers. The watch includes at least one processing and control circuit provided with a time base, hands to indicate a time, the hands being driven by a motorized device controlled by the processing and control circuit, and a device to store identification data. In this photoelectric rotary encoder, an optical element that lets a stray beam component of the light beam from the light source escape via a side surface of the optical element, is disposed in front of the substrate on which the light source and the photodetector are disposed. The approach also involves causing, at least in part, a predetermined amount of a toner to be input into the toner container by a filling process when the toner container is in the filling position.