Lighting system with auxiliary lamp control circuit

Claim 1

Lighting system comprising, in combination, a gaseous discharge lamp, voltage supply means connected to said gaseous discharge lamp, ballast means connected between said gaseous discharge lamp and said voltage supply means, said gaseous dscharge lamp having a low voltage across the same during its starting period, having an intermediate voltage across the same during its normal operation period, and having a high voltage across the same during its non-operating period, an auxiliary lamp serving as a stand-by lamp for said gaseous discharge lamp, means for connecting said auxiliary lamp to a source of electrical current, and control means selectively responsive to said low, intermediate, and high voltages non-operating and low voltage starting periods of said gaseous discharge lamp and for turning off said auxiliary lamp during said intermediate voltage normal operation period of said gaseous discharge lamp, said control means comprising first and second relay means, said first relay means having a first coil connected across said gaseous discharge lamp and normally closed first switch contacts connected in series with said auxiliary lamp, said second relay means having a second coil connected in parallel with said first coil and normally closed second switch contacts connected in series with said first coil, said first coil operating during said intermediate voltage period to open said first switch contacts for turning off said auxiliary lamp, said second coil operating during said high voltage period to open said second switch contacts for turning on said auxiliary lamp, both said first and second coils being non-responsive to said low voltage for maintaining said auxiliary lamp on during said starting period, said first and said second coil each having linear impedance associated therewith, the linear impedance associated with said first coil being lower than the linear impedance associated with said second coil.