To provide a light circuit having a light transmitting passage from which the light hardly slips outside in an incident part to the light transmitting passage from the light transmitting end by providing the light transmitting passage with a gradually expanding cross-sectional part as the cross section of the light transmitting passage separates from the light transmitting end, at its light transmitting end side end part.
The light output end 5a on a light-electric circuit 1 mounted on a base board 10 and the light input end 6a on the base board 10, are connected to each other by a light transmitting passage 4a to form a single light circuit. A gradually expanding cross-sectional part 40a as the cross section of the light transmitting passage 4a separates from the light output end 5a, is formed at an end part on the light output end 5a side of the light transmitting passage 4a. The direction of the light to an inner wall surface becomes equal to or larger than a critical angle by an inclined face of an inner wall of the light transmitting passage 4a with a procedurally expanding cross-sectional part 40a. Therefore, the light is reflected in the light transmitting passage 4a, and slipping-out of the light to an external part can be prevented.
HIROTA MASANORI
SAKASAI KAZUHIRO
SHIOTANI TAKEKAZU
HAMADA TSUTOMU
FUNADA MASAO
OZAWA TAKASHI
