LIGHTING DEVICE

To provide a lighting device capable of suppressing overheat in a constant current circuit when a short-circuit failure occurs in a light source.SOLUTION: A lighting device 10 comprises: an AC-DC chopper circuit 14 which rectifies an AC voltage and supplies a DC current to a light source 40 including one or more light-emitting elements; a driving circuit 72 which controls oscillation of the AC-DC chopper circuit 14; a constant current circuit 50 which includes a switch element 51 connected in series to the light source 40 and maintains a constant current supplied to the light source 40 by controlling the switch element 51; a control power supply circuit 121 which supplies power to the driving circuit 72 and the constant current circuit 50; an oscillation detection circuit 170 which detects an oscillation stop of the AC-DC chopper circuit 14; and a protection circuit 150 which maintains a cut-off state of the switch element 51 when the oscillation detection circuit 170 detects the oscillation stop of the AC-DC chopper circuit 14 in a state in which the control power supply circuit 121 is supplying power to the driving circuit 72 and the constant current circuit 50.SELECTED DRAWING: Figure 1 【課題】光源において短絡故障が発生した場合に、定電流回路における過熱を抑制できる点灯装置を提供する。【解決手段】点灯装置１０は、交流電圧を整流し、１以上の発光素子を含む光源４０に直流電流を供給するＡＣ－ＤＣチョッパ回路１４と、ＡＣ－ＤＣチョッパ回路１４の発振を制御する駆動回路７２と、光源４０に直列接続されるスイッチ素子５１を有し、スイッチ素子５１を制御することで、光源４０に供給される電流を一定に維持する定電流回路５０と、駆動回路７２及び定電流回路５０に電力を供給する制御電源回路１２１と、ＡＣ－ＤＣチョッパ回路１４の発振停止を検出する発振検出回路１７０と、制御電源回路１２１が、駆動回路７２及び定電流回路５０に電力を供給している状態で、発振検出回路１７０がＡＣ－ＤＣチョッパ回路１４の発振停止を検出した場合に、スイッチ素子５１を遮断状態に維持する保護回路１５０と、を備える。【選択図】図１