Hybrid light source

摘要

The invention relates to a dimmable hybrid light source adapted to receive a phase-controlled voltage. The hybrid light source comprises a discrete-spectrum light source circuit comprising a discrete-spectrum lamp, a continuous-spectrum light source circuit comprising a continuous-spectrum lamp operable to conduct a continuous-spectrum lamp current, a zero-crossing detect circuit for detecting when the magnitude of the phase-controlled voltage becomes greater than a predetermined zero-crossing threshold voltage each half-cycle of the phase-controlled voltage, and a control circuit coupled to both the discrete-spectrum light source circuit and the continuous-spectrum light source circuit for individually controlling the amount of power delivered to each of the discrete-spectrum lamp and the continuous-spectrum lamp in response to the zero-crossing detect circuit, such that a total light output of the hybrid light source ranges from a minimum total intensity to a maximum total intensity, the control circuit operable to control the discrete-spectrum lamp when the total light intensity is below a transition intensity, such that the percentage of the total light intensity produced by the continuous-spectrum lamp is greater than the percentage of the total light intensity produced by the discrete-spectrum lamp when the total light intensity is below the transition intensity. Thereby the control circuit controls the amount of power delivered to the continuous-spectrum lamp to be greater than or equal to a minimum power level after the magnitude of the phase-controlled voltage becomes greater than the predetermined zero-crossing threshold voltage each half-cycle of the phase-controlled voltage when the total light intensity is above the transition intensity.