Circuit arrangement for use with vehicles safety arrangement

Claim 2

An arrangement for preventing a vehicle engine from being started unless a safety harness for the occupants of the vehicle is in position, comprising means for generating an alternating signal, a first electrical conductor associated with a seat of the vehicle and acting as one plate of a capacitor, a second electrical conductor carried by the safety harness associated with said seat and acting as another plate of the capacitor, the body of an occupant of the seat providing, when within the harness, a dielectric to cause an alternating current flow from said generating means through said capacitor, said signal generating means being connected to one of said plates, first switching means operable by interengagement of parts of the harness, and second switching means operable to complete a circuit to a starting device for the vehicle only when there is an alternating current flow through said capacitor and when said first switching means is operated.

Claim 3

An arrangement as claimed in claim 1 in which said second switching means comprises an electro-magnetic relay, and there is provided third switching means responsive to said alternating current flow to cause said relay to be energised.

Claim 4

An arrangement as claimed in claim 2 in which said third switching means is a thyristor.

Claim 5

An arrangement as claimed in claim 3 which includes a transistor responsive to a half-cycle of said alternating current through said capacitor to apply a switching signal to the gate of said thyristor.

Claim 6

An arrangement as claimed in claim 2 in which the first switching means is in series with said third switching means.

Claim 7

An arrangement as claimed in claim 1 which includes a third electrical conductor associated with a further seat of the vehicle, a fourth electrical conductor carried by the safety harness associated with said further seat, said third and fourth conductors acting as first and second plates respectively of a further capacitor, an occupant of said further seat providing, when within the harness, a dielectric to cause an alternating current flow through said further capacitor, fourth switching means operable by the presence of an occupant of said further seat to prevent said second switching means from completing the circuit to said starting device, fifth switching means operable by interengagement of parts of the harness associated with said further seat, and sixth switching means operable in response to an alternating current flow between said first and second plates of said further capacitor and also when said fourth and fifth switching means are operated to enable said second switching means to complete the circuit to said starting device.

Claim 8

An arrangement as claimed in claim 6 in which said sixth switching means comprises a second electro-magnetic relay, and there is provided seventh switching means responsive to said current flow in said further capacitor to cause said second relay to be energised.

Claim 9

An arrangement as claimed in claim 7 in which said seventh switching means is a second thyristor.

Claim 10

An arrangement as claimed in claim 8 which includes a second transistor responsive to a half-cycle of said alternating current between said first and second plates of said further capacitor to apply a switching signal to the gate of said second thyristor.

Claim 11

An arrangement as claimed in claim 6 in which the fifth switching means is in series with the seventh switching means.

Claim 12

An arrangement as claimed in claim 6 in which said fourth switching means is responsive to the weight of an occupant of said further seat.

Claim 13

An arrangement as claimed in claim 6 which includes a fifth electrical conductor associated with said further seat and providing a third plate of said further capacitor, an occupant of said further providing, in use, a dielectric to cause an alternating current to flow between said first and third plates of said further capacitor, said fourth switching means being responsive to the current flow between said first and third plates.

Claim 14

An arrangement as claimed in claim 12 in which said fourth switching means is a third electro-magnetic relay and there is provided eighth switching means responsive to alternating current flow between said first and third plates to cause said third relay to be energised.

Claim 15

An arrangement as claimed in claim 13 in which said eighth switching means is a third thyristor.

Claim 16

An arrangement as claimed in claim 14 which includes a third transistor responsive to a half-cycle of said alternating current between said first and third plates to apply a switching signal to said third thyristor.

Claim 17

An arrangement as claimed in claim 1 which includes warning apparatus operable when the second switching means is not completing said circuit to said starting device.

Claim 18

An arrangement as claimed in claim 16 in which said warning apparatus comprises an electrically operated visual and audible warning devices.

Claim 19

An arrangement as claimed in claim 6 which includes a warning apparatus operable to provide an audible indication when either the second or the sixth switching means are not completing the circuit to said starting device, and a pair of electric lamps operable by the second and sixth switching means respectively when the latter are not completing the circuit to said starting device.