A seat belt status monitoring system for use with one or more seat belts of an
automotive vehicle. The system includes a status monitor incorporated into the
seat belt buckle and has a receiver and operator signaling device located in the
instrument panel. The status monitor utilizes a piezoelectric element to generate
an electrical signal that is fed to a transmitter to generate a wireless signal
from the buckle. A mechanical sensing member is used to activate the piezoelectric
element to generate its electrical signal by imparting a mechanical force on the
piezoelectric during insertion and removal of the seat belt tongue from the buckle.
A microswitch in the buckle is used by the transmitter to determine whether the
seat belt is latched or unlatched, and this information is conveyed by the transmitted
wireless signal. The wireless signal uniquely identifies the particular seat belt
buckle from which it is transmitted so that the receiver can keep track of the
status of each of a number of different seat belt buckles within the vehicle.