GB1315106A - Motor vehicle seat belt warning system - Google Patents

Abstract

1315106 Warning devices FORD MOTOR CO Ltd 9 Feb 1972 6007/72 Addition to 1281791 Heading B7H In a motor vehicle first and second radio aerials are mounted in the seat and the associated seat belt respectively, one aerial acting as a transmitter through a high frequency oscillator and the other acting as a detector from a detecting circuit, and arranged so that a logic circuit energizes an alarm unless the signals at the detector are of relatively low level which indicates that the belt passes in front of a passenger since the radio waves are then attenuated by the passenger. In a preferred embodiment receiving aerials 11, 12, Fig. 1, may be flexible printed circuits concealed behind the trim panel of the seat. An electrical conductor 20, Fig. 2 extends along the webbing 17 of the seat belt. The circuit in Fig. 3, functions so that a visible and/or audible alarm 31 is actuated in first or reverse gears unless both the buckle switch 23 is fastened and the belt passes in front of the seat occupant. A seat load sensing switch 28 is closed if the seat is occupied by a person of weight above 50 lbs. Gear-box switch 32 is closed when second, third or fourth gear is engaged to operate via delay circuit 33 a more obtrusive alarm circuit 34 which may sound the horn or flash the indicator lights. If this is ignored a further delay circuit 36 actuates a switch 35 to cut off the ignition or fuel line. The buckle switch 23 may be replaced by an additional aerial in the buckle and detecting means is arranged to indicate that the buckle is fastened to the seat belt when a high frequency signal is received from the additional aerial.