Vehicle occupant sensing apparatus and method

A vehicle occupant sensing apparatus for use with an associated vehicle having a seat, said vehicle occupant sensing apparatus comprising:

• (1) a first range measurement system for sensing a first distance from said first range measurement system toward the first area of the seat;
• (2) a second range measurement system for sensing a second distance from said second range measurement system toward the second area of the seat;
• (3) a third range measurement system for sensing a third distance from a third range measurement system toward the third area of the seat, said first and second range measurement systems being mounted to the vehicle roof above a seat cushion portion of the seat and said third range measurement system being mounted on the instrument panel transversely of a back rest portion of the seat, said second range measurement system being located forwardly of said first range measurement system, and,
• (4) a controller, said controller including
• (a) operating means for operating said firsts, second and third range measurement systems, said first, second and third range measurement systems are ultrasonic devices, said operating means comprising:
• first pulse rate operating means for operating said first, second and third range measurement systems at first pulse rates T1A, T2A and T3A respectively;
• and, second pulse rate operating means for operating said first, second and third range measurement systems at second pulse rates T1B, T2B and T3B respectively, and
• (b) determining means for determining if an object is located on the seat in response to said first, second and third distances, said determining means also determining if the object is a child seat.