Sensing system for sensing state of wear of seatbelt

Claim 1

A sensor system for sensing a state of wear of a seat belt comprising, in combination, a first normally open seat switch adapted to be closed when sat on by a vehicle occupant, a second normally open switch adapted to be closed by the fastening of a seat belt, a FLIP-FLOP circuit including a pair of input terminals operatively coupled to said first and second switches respectively and an output, said FLIP-FLOP circuit being operated in response to the operation of either of said first and second switches, a time delay circuit interposed between one input to said FLIP-FLOP circuit and said first switch, a first gate circuit including a pair of inputs connected to the output of said FLIP-FLOP circuit and said second switch, respectively, and additional means are provided including a transistor operatively connected to said first gate circuit and responsive to an output signal from said first gate circuit, a starter relay including a winding connected to said transistor and a set of contacts connected to both a key operating switch and a starter winding, said set of contacts adapted to be open when said first switch is closed while said second switch is open, as well as when said second switch is closed followed by the closure of said first switch, thereby preventing operation of an associated engine and adapted to be closed when said second switch closes after said first switch closes, allowing activation of said engine, and means operatively coupled for preventing electric power from being supplied to said starter winding through said key operating switch once the associated engine is started.