A semiconductor photodetector device includes a light receiving operation section converting incident light to an electric signal and a current amplifying operation section amplifying the electric signal. In one example, a request for a position to be computed within a predefined period of time is received. After the orientation, a computer is provided and installed in the homes of each participant. The panel receives the analog data signals or the reset data signals and displays normal images, reset images or both according to the analog data signals and the reset data signals. Hence, even in a situation in which an operator necessarily tightly presses hisher face against a front surface of a chassis, the voice transmission path is ensured to a certain extent, and thus the sound collecting property is ensured to some degree or more. A cutting edge is embodied in the transition area from at least one of the lateral surfaces to the top or bottom surface and wherein the at least one lateral surface has alternate projecting and recoiling sections viewed from above or from below.