In a seat belt retractor, as the rotation of a pawl holder of a locking member in the webbing unwinding direction is stopped by a locking mechanism in emergency, a reel receives a force on a protrusion by impact load applied to the webbing with the inertia of an occupant. The substrate further includes at least one signal layer having a plurality of electrical signal traces formed thereon. Elements of the light modulator may be controlled to adjust the intensity of light emanating from corresponding areas on the screen. The system processes a user command received via the cable network, including an advertising information search command, and provides advertising information retrieved via the cable network. Electric discharge from the secondary battery to the load is shut off at full charge of the secondary battery, so that a load current fed from the secondary battery does not flow and, hence, a decrease in battery capacity of the secondary battery which would be caused by the load does not take place.