Differential relay arrangement for determining when one of two cooperating lamps, particularly vehicle lamps, is not operating

In combination with an indicator and at least one pair of cooperating vehicular lamps including a first lamp and a second lamp, an arrangement for activating said indicator when only one of said pair of cooperating vehicular lamps is operating, the arrangement comprising at least one cylindrical coil unit having a winding comprised of two wires including a first wire and a second wire;

• first means connecting said first wire to said first lamp and operative when said first lamp is operating for causing said first wire to carry a first current producing a first magnetic field;
• second means connecting said second wire to said second lamp and operative when said second lamp is operating for causing said second wire to carry a second current producing a second magnetic field which opposes and at least partly cancels out said first magnetic field;
• an encapsulated magnetic field responsive switch unit comprised of a magnetic field responsive switch encapsulated in a gas-tightly sealed capsule filled with a protective gas, the encapsulated switch unit being positioned in the center of said coil unit and oriented to become activated when only a single one of said fields is produced and to remain unactivated when both said fields are produced;
• and means connecting said encapsulated switch unit to said indicator and operative for activating said indicator when said encapsulated switch unit becomes activated, wherein said arrrangement further includes a base plate provided on one side thereof with a plurality of soldering lugs and also provided with a cut-out, and wherein said coil unit is provided with a foot portion provided with at least one locking portion which engages and is locked in said cut-out fixedly mounting said coil unit on said base plate, and wherein said base plate is provided with a soldering lug projecting into said cut-out and into the interior of said coil unit, and wherein said base plate is provided with a plurality of additional soldering lugs, and wherein one terminal of said encapsulated switch unit is electrically connected to the soldering lug which projects into said cut-out, and further including a current-limiting resistor having one terminal connected to the other terminal of said encapsulated switch unit and having an other terminal electrically connected to one of said additional soldering lugs.

In a combination with an indicator and a plurality of pairs of vehicular lamps, each pair of lamps including a respective first lamp and a cooperating respective to second lamp, an arrangement for activating said indicator when only one of the two lamps of one of said pairs of lamps is operating, the arrangement comprising a plurality of cylindrical coil units arranged coaxially one within another and each corresponding to a respective one of said plurality of pairs of lamps and each having a respective winding comprised of two wires including a respective first wire and a respective second wire;

• first means connecting the first wire of each of said coil units to the first lamp of the respective one of said pairs of lamps and operative when the first lamp of the respective pair of lamps is operating for causing the respective first wire to carry a first current producing a respective first magnetic field;
• second means connecting the second wire of each of said coil units to the second lamp of the respective one of said pairs of lamps and operative when the second lamp of the respective pair of lamps is operating for causing the respective second wire to carry a second current producing a respective second magnetic field;
• an encapsulated magnetic field responsive switch unit comprised of a magnetic field responsive switch encapsulated in a gas-tightly sealed capsule filled with a protective gas, the encapsulated switch unit being positioned in the center of the innermost one of said coil units and oriented to become activated when only a single one of the two fields associated with any one of said coil units is produced;
• and means connecting said encapsulated switch unit to said indicator and operative for activating said indicator when said encapsulated switch unit becomes activated, wherein said arrangement further includes a base plate provided with a cutout, and wherein each coil unit is provided with a foot portion provided with at least one locking portion which engages and is locked in said cutout fixedly mounting said coil unit on said base plate, and wherein said base plate is provided with a soldering lug projecting into said cutout and into the interior of said coil unit and connected to one terminal of said encapsulated switch unit.

In a combination with an indicator and a plurality of pairs of vehicular lamps, each pair of lamps including a respective first lamp and a cooperating respective second lamp, an arrangement for activating said indicator when only one of the two lamps of one of said pairs of lamps is operating, the arrangement comprising a plurality of cylindrical coil units arranged coaxially one within another and each corresponding to a respective one of said plurality of pairs of lamps and each having a respective winding comprised of two wires including a respective first wire and a respective second wire;

• first means connecting the first wire of each of said coil units to the first lamp of the respective one of said pairs of lamps and operative when the first lamp of the respective pair of lamps is operating for causing the respective first wire to carry a first current producing a respective first magnetic field;
• second means connecting the second wire of each of said coil units to the second lamp of the respective one of said pairs of lamps and operative when the second lamp of the respective pair of lamps is operating for causing the respective second wire to carry a second current producing a respective second magnetic field;
• an encapsulated magnetic field responsive switch unit comprised of a magnetic field responsive switch encapsulated in a gas-tightly sealed capsule filled with a protective gas, the encapsulated switch unit being positioned in the center of the innermost one of said coil units and oriented to become activated when only a single one of the two fields associated with any one of said coil units is produced;
• and means connecting said encapsulated switch unit to said indicator and operative for activating said indicator when said encapsulated switch unit becomes activated, wherein said arrangement further includes a base plate provided on one side thereof with a plurality of soldering lugs and also provided with a cut-out, and wherein each coil unit is provided with a foot portion provided with at least one locking portion which engages and is locked in said cut-out fixedly mounting said coil unit on said base plate, and wherein said base plate is provided with a soldering lug projecting into said cut-out and into the interior of said coil unit, and wherein said base plate is provided with a plurality of additional soldering lugs, and wherein one terminal of said encapsulated switch unit is electrically connected to the soldering lug which projects into said cut-out, and further including a current-limiting resistor having one terminal connected to the other terminal of said encapsulated switch unit and having an other terminal electrically connected to one of said additional soldering lugs.