Abstract: A method of charging a storage battery comprising executing an n(n≧2)-stage constant current charging process charging the battery with a constant current while monitoring a terminal voltage of the battery, the current decreasing stepwise n−1 times every time the terminal voltage coincides with a current switching voltage. The method further comprises measuring a depth of discharge of the battery immediately before charging and executing an additional charging process before the n-stage constant current charging process when the depth of discharge is deeper than a reference depth of discharge, the additional charging process charging the battery with an additional constant current larger than an initial current in the n-stage constant current charging process and switching the additional current to the initial current when the terminal voltage coincides with the current switching voltage, so as to attain a rapid charging of the battery at a low cost.

Abstract: A plurality of frame image signals are successively applied to an image signal encoder. A motion region of an incoming frame image signal is extracted and then approximated in shape to a polygon. The vertices of the polygon are determined and then the coordinate values of the vertices are calculated and transmitted. Further, in the event that the incoming image signal includes a region which is required to undergo orthogonal transformation, the region are extracted and then divided into a plurality of small regions. Following, each of the divided small regions is approximated in shape to a polygon and then the vertices thereof are detected. Subsequently, the coordinate values of the vertices are calculated and then transmitted. Consequently, the data to be transmitted can effectively be reduced.