GB1348774A - Lighting systems for road vehicles - Google Patents

Abstract

1348774 Vehicle lighting systems JOSEPH LUCAS (INDUSTRIES) Ltd 11 June 1971 [27 June 1970] 31284/70 Heading H2H A vehicle headlamp system each lamp having a dipped and a main beam filament comprises a branch connecting parallel circuit each containing one of the filaments so that failure of a filament selected by the dip switch results in completion of a circuit through the other to illuminate it at reduced intensity. As shown, a dipswitch 15 having two fixed contacts 16, 17 is connected to one side of the battery 11 via a main lighting switch 12-14. In the position shown, dipped beam filaments 26, 36 are illuminated via the circuits comprising relay coils 23, 33, diodes 24, 34 and fuses 25, 35 respectively. Main beam filaments 22, 32 may be illuminated via contact 16, coils 18, 28, diodes 19, 29 and fuses 21, 31 respectively. Each of the coils 18, 23, (and similarly 28, 33) when energized serves to hold normally closed contacts 18a, 18b, (28a, 28b) in the open position whereas in the event of failure of the selected filament, e.g. 26, cessation of current in coil 23 causes closing of the contacts to illuminate a warning lamp 27 and the other filament 22 at a reduced intensity via resistor 20 current being reduced in coil 23 sufficiently by the presence of the resistor 20, that contacts 18a, 18b remain closed. In a modification, Fig. 2 (not shown), the pairs of colis 18, 23 and 28, 33 are each replaced by a single coil (18), (28) respectively located adjacent the earthed terminal and connected to both filaments, and in a further modification the contacts 18a, 28a are each replaced by two contacts, one in each filament circuit each operated by the relay coil in the associated parallel circuit.