Patent ID: 8049441

Claim:
A ballast circuit, comprising, a first lamp set, comprising: a first inductor; and a plurality of containing areas, each of the containing areas being adapted to contain a lamp so that the lamps are connected in series, and the containing areas being connected in series with the first inductor; a second lamp set being connected in parallel with the first lamp set, comprising: a second inductor, being coupled to the first inductor; at least one containing area, being connected in series with the second inductor, each of the at least one containing area being adapted to contain a lamp so that the at least one lamp is connected in series with the second inductor; a detection circuit, being coupled to each of the containing areas of the first lamp set and each of the containing areas of the second lamp set so that the detection circuit, the first inductor, the second inductor, and the lamps contained in the containing areas form a series connection, the detection circuit being configured to receive a direct current (DC) voltage signal and to generate a first signal; and a latch circuit coupled to the detection circuit, being configured to receive the first signal from the detection circuit and selectively start the ballast circuit in response to the first signal.