ROTARY JOINT

PROBLEM TO BE SOLVED: To enable stable transmission/reception even if images are highly fine and data is rapid by achieving bidirectional optical transmission over a fixed part and a rotary part combined therewith rotatably at a low cost and with a small scale. SOLUTION: A tubular member 101 is formed so that each end part has a circumferential surface which reduces its radius as it comes away from other end part or a circumferential face which reduces its radius as it comes near other end part. In a rotary part 2, a rotary part side light-receiving element 12 is provided on an optical path wherein a first light signal injected from an end part at a fixed part 3 side of the tubular member 101 is led out by light reflection in a circumferential face of an end part at the rotary part 2 side, and a rotary part side light-emitting element 13 which injects a second light signal to a circumferential face is also provided. The fixed part 3 includes a fixed part side light-emitting element 11 which injects the first light signal to a circumferential face of an end part at the fixed part 3 side of the tubular member 101 and includes a fixed part side light-receiving element 14 on an optical path wherein an injected second light signal is led out by light reflection in a circumferential face. COPYRIGHT: (C)2009,JPO&INPIT