Patent ID: 8212497
Filing Date: 2012-07-03
Classification: H05B

Abstract:
1. A ballast for powering a lamp load comprising at least one gas discharge lamp having a pair of lamp filaments, the ballast comprising: an inverter; an output circuit coupled to the inverter, the output circuit comprising a plurality of output connections adapted for coupling to the at least one gas discharge lamp; a filament heating control circuit coupled to the inverter and to the output circuit, and operable to provide, in conjunction with the output circuit, heating of the filaments of the at least one lamp, wherein the filament heating control circuit includes first and second inputs; a control circuit coupled to the output circuit, to the inverter, and to the filament heating control circuit, wherein the control circuit is operable: wherein the control circuit includes: and wherein the control circuit is further operable: wherein the ballast is operable, following the lamp type detection period, to provide heating of the lamp filaments in dependence upon: (i) the determined number of lamps with both filaments intact; and (ii) the determined lamp type of the lamps with both filaments intact, and wherein the inverter includes an inverter driver circuit, comprising: at least one input coupled to the at least one control output of the control circuit; and an output coupled to the second input of the filament heating control circuit; and wherein the inverter driver circuit is operable to provide a filament heating control signal at the output in dependence upon the at least one control signal provided by the control circuit.