Abstract: An optical fiber is optically coupled to a light-receiving/emitting element contained in an interface box. The coupling structure is composed of a cylindrical ferule water-tightly inserted into a through-hole formed in a wall of the interface box, a resilient grommet coupled to the ferule and a coupler having the light-receiving/emitting element. An optical fiber is inserted into coaxially formed center holes of the ferule and the grommet, and an axial end of the optical fiber is exposed at an axial end of the ferule. The coupler is coupled to the ferule so that the light-receiving/emitting element directly faces the exposed end of the optical fiber to establish an optical connection at a minimized connection loss.

Abstract: A load sensor includes a optical fiber sensor that provides output analog signals in response to shocks of various magnitudes caused by hits by a vehicle on various objects, two or more amplifiers each of which approximates a non linear function of the analog signals and a unit that converts the linear functions into digital data. Therefore, each analog signal either in a lower magnitude range or a higher magnitude range can be amplified by one of the amplifiers that has a more suitable gain, so that the magnitude of the shock can be accurately converted into digital data for a pedestrian protection airbag system.

Abstract: An optical fiber is optically coupled to a light-receiving/emitting element contained in an interface box. The coupling structure is composed of a cylindrical ferule water-tightly inserted into a through-hole formed in a wall of the interface box, a resilient grommet coupled to the ferule and a coupler having the light-receiving/emitting element. An optical fiber is inserted into coaxially formed center holes of the ferule and the grommet, and an axial end of the optical fiber is exposed at an axial end of the ferule. The coupler is coupled to the ferule so that the light-receiving/emitting element directly faces the exposed end of the optical fiber to establish an optical connection at a minimized connection loss.