Patent ID: 8106738

Claim:
A ballast for multiple lamps, comprising: a rectangular cylindrical bobbin provided with a partition formed in a center portion of an inner space thereof; a first coil wound around an outer surface of the bobbin to enclose the outer surface and configured to control current flowing through a first discharge lamp; an insulating sheet stacked on the first coil to enclose the first coil; a second coil wound around the insulating sheet to enclose the insulating sheet and configured to control current flowing through a second discharge lamp; and first and second cores, each configured to include two paired core elements, which have ∩- and ∪-shaped vertical sections and are vertically coupled to each other on both sides of the bobbin, wherein ends of the core elements disposed outside the bobbin are connected to each other, and ends of the core elements disposed inside the bobbin are spaced apart from each other by an interval corresponding to the thickness of the partition of the bobbin to form a path for magnetic flux.