| 摘要 |
PROBLEM TO BE SOLVED: To provide a lighting device that has a broad lighting control range and suppress flicker and wobble of output current at a light controlling transition period.SOLUTION: A lighting device 1 for supplying current to a solid light-emitting element (LED2) has a full-wave rectification circuit 19, a buck-boost type DC/DC converter 20 to which full-wave-rectified current is supplied from the full-wave rectification circuit 19 and which has a switching element 14, and a control circuit 10 for performing on and off control on the switching element 14. The control circuit 10 controls the switching element 14 in a current critical mode when the effective value of the output current is adjusted to a predetermined threshold value or more, controls the switching element 14 in a discontinuous mode when the effective value of the output current is adjusted to a value less than the threshold value, and changes the switching frequency discontinuously so that the effective value of the output current varies continuously when the control mode of the switching element 14 is switched between the current critical mode and the discontinuous mode.SELECTED DRAWING: Figure 1 |
