Patent ID: 7751861

Claim:
A portable telephone comprising: a first casing having a display panel; a second casing which has an operation panel and which is coupled to the first casing so as to be foldable or developable; and an optical signal transmission section for performing signal transmission between the first casing and the second casing by optical signals, wherein the optical signal transmission section includes: optical element parts which are placed in the first casing and the second casing, respectively, and which perform at least one of transmission and reception of optical signals; an optical transmission medium which is stretched between the first casing and the second casing so as to optically couple the optical element part of the first casing and the optical element part of the second casing to each other and which has plugs provided at its both ends; and receptacles which are placed in the first casing and the second casing, respectively, and which have the plugs of the optical transmission medium fitted and held thereto while having the optical element parts fitted and held thereto so that the optical element parts and the optical transmission medium are optically coupled to each other, and wherein the receptacles allow the plugs of the optical transmission medium and the optical element parts to be fitted thereto along a direction perpendicular to an optical axis of the optical transmission medium, and the receptacles and the optical element parts have fixing-use engagement portions, respectively, which are to be engaged with and fixed to each other in a state that the optical element parts are fitted to the receptacles, respectively.