A temperature of a mobile telephone set is detected, and when the temperature exceeds a predetermined first threshold, a video signal encoding unit is changed from the predetermined normal encoding rate to a reduced encoding rate, which is lower than the predetermined normal encoding rate. The functions are assigned to the interface sections such as HDMI sections connected with the video signal sources, via switches for example, to minimize the number of the function blocks to be provided. When the ribs are pulled apart, the cover is expanded to cover an automobile.