Abstract: A luminaire according to one embodiment includes a DC power supply circuit, a switching power supply, and a lighting load. The DC power supply circuit converts an AC voltage controlled in phase to a DC voltage. The switching power supply is connected to the DC power supply circuit, and is controlled so that an input current becomes a constant current. The lighting load is connected as a load circuit of the switching power supply.

Abstract: According to one embodiment, a lighting circuit includes a high potential input terminal, a low potential input terminal, a high potential output terminal, a low potential output terminal, first and second switching elements, first and second rectifying elements, an inductor and a control circuit. The first switching element has one end connected to the high potential input terminal. The first rectifying element is connected between one other end of the first switching element and the low potential input terminal. The inductor has one end connected to the one other end of the first switching element. The second switching element is connected between one other end of the inductor and the low potential input terminal. The second rectifying element is connected between the one other end of the inductor and the high potential output terminal. The control circuit turns on or off the first and second switching elements.

Abstract: According to one embodiment, a lighting circuit includes a high potential input terminal, a low potential input terminal, a high potential output terminal, a low potential output terminal, first and second switching elements, first and second rectifying elements, an inductor and a control circuit. The first switching element has one end connected to the high potential input terminal. The first rectifying element is connected between one other end of the first switching element and the low potential input terminal. The inductor has one end connected to the one other end of the first switching element. The second switching element is connected between one other end of the inductor and the low potential input terminal. The second rectifying element is connected between the one other end of the inductor and the high potential output terminal. The control circuit turns on or off the first and second switching elements.

Abstract: In a power supply device 1 including a switching element 12 and a control section 11 configured to control the switching element 12, the control section 11 receives an input of a first signal fluctuating according to an output voltage of the power supply device 1 and fixed with respect to an input voltage of the power supply device 1 and a second signal, the amplitude of which fluctuates according to the input voltage of the power supply device 1, and controls ON or OFF of the switching element 12 according to time until a value of the second signal reaches a value of the first signal.

Abstract: In a power supply device 1, power factor improving circuits 15 and 16 are connected to an external power supply and configured to supply electric power to a driving circuit 19, improve a power factor of an input current to the driving circuit 19, and perform an interleave operation. The driving circuit 19 subjects an LED 111 to lighting control.

Abstract: A luminaire according to one embodiment includes a DC power supply circuit, a switching power supply, and a lighting load. The DC power supply circuit converts an AC voltage controlled in phase to a DC voltage. The switching power supply is connected to the DC power supply circuit, and is controlled so that an input current becomes a constant current. The lighting load is connected as a load circuit of the switching power supply.