Passenger detecting system and air bag apparatus using the same

An air bag apparatus comprising a passenger detecting system and an air bag control system,

• wherein said passenger detecting system comprises
• an antenna electrode provided in a seat to be occupied by a passenger;
• a signal generating circuit for generating and supplying a supply signal to said antenna electrode though a resistor such that an electric field is generated around said antenna electrode;
• a detecting circuit including said resistor, for detecting a direct current data signal from a line voltage associated with a voltage drop across said resistor, wherein said line voltage changes depending upon an object on said seat;
• and
• a control circuit for determining from said detected direct current data signal, whether or not a passenger is present in said seat and, when a passenger is present, whether said passenger is an adult or a child, and
• wherein said air bag control system is connected to said control circuit and sets an air bag to either an expansion allowed state or an expansion inhibited state based on the determination result by said control circuit.