Abstract: A passenger protecting apparatus for inflating an air bag or tightening a seat belt is provided that is smaller in size and more reliable than any previously known passenger protecting apparatus. The passenger protecting apparatus has two switches connected in series with a squib. The switches are controlled by a control unit using independent program routines in a redundant manner. The control unit combines front collision and side collision detection in one unit. The control unit controls the switches based on the outputs of several acceleration sensors, by comparing their respective outputs to threshold values.

Abstract: A crew protection apparatus includes a DC power source; a squib connected in series with the DC power source; a plurality of switch circuits inserted between the DC power source and the squib or between the squib and the ground side; an acceleration sensor for detecting an acceleration caused by a collision; a collision determination circuit for, when receiving an acceleration signal from the acceleration sensor, determining the scale of a collision on the basis of the acceleration signal and outputting an ignition control signal in coincident with the timing supplied to the switch circuit and further outputting a current control signal in synchronism with the ignition control signal when it is determined that the collision is a serious collision; and a current limit circuit for limiting the magnitude of an ignition current flowing through the squib in accordance with the ignition control signal and the current control signal from the collision determination circuit.

Abstract: In a crew member detecting device, an acoustic wave generator element mounted on a vehicle body generates a standing wave between the acoustic wave generator element and a bucket seat, and an acoustic wave receiver element is provided in the region of the standing wave, to detect the presence of a person on the bucket seat from variations in the output of the acoustic wave receiver element which are due to the movement of the person on the bucket seat.