GB1281791A - Safety belt alarm system - Google Patents

Abstract

1281791 Warning devices FORD MOTOR CO Ltd 20 March 1971 7644/71 Heading B7H In a motor vehicle an alarm is energized if a safety belt passes behind a passenger thus preventing intercommunication between a transmitter and receiver. The transmitter 22, Fig. 1, may be mounted on the seat belt 17 and the receiver 23 on the header rail 46 or instrument panel 47 or vice versa or the transmitter and receiver may both be mounted on the body structure and the belt arranged to reflect the signals. The wavelengths used may be ultrasonic, radio, infra-red or visible. In a preferred embodiment an alarm signal is produced unless all persons occupy their seats so that a seat weight sensor 25, Fig. 2, is on, seat belt switch 24 in the latch 20 is closed and the belt is in front of the passenger. When a seat is unoccupied the input seat sensor 25 connects the input 48 directly to input 30 to by-pass seat belt switch 24 and the transmitter receiver sets 22, 23. With all seat belts correctly fastened and the ignition 27 turned on timer 34 cuts out the transmitter/ receiver sets 10 to 30 sees. later so that audio and visual alarms 36, 35 are not activated by activities such as reading. With the vehicle in second or higher gear, gear switch 38 connects the ignition to a further alarm 37 which sounds the horn and flashes the head lights and first and second relays 39, 42 are in circuit so that on entering second or higher gears the further alarm is energized immediately if the seat belts are unfastened but not after a time interval produced by timer 44 if the belts are already fastened but subsequently unfastened.