Abstract: A power supply includes: a step-down chopper unit for stepping down a DC voltage from a DC power source to a voltage required for lighting; and a dimming control unit which dims the light source by alternately repeating a switching ON period during which a drive signal having a frequency higher than that of the dimming signal is supplied to the switching element and a switching OFF period during which the supply of the drive signal to the switching element is stopped. Further, the power supply includes an inrush current prevention unit for preventing an inrush current occurring when the DC power source is turned on, and a compensation unit which applies a drive voltage to the thyristor in the switching OFF period.

Abstract: A power supply includes: a step-down chopper unit for stepping down a DC voltage from a DC power source to a voltage required for lighting; and a dimming control unit which dims the light source by alternately repeating a switching ON period during which a drive signal having a frequency higher than that of the dimming signal is supplied to the switching element and a switching OFF period during which the supply of the drive signal to the switching element is stopped. Further, the power supply includes an inrush current prevention unit for preventing an inrush current occurring when the DC power source is turned on, and a compensation unit which applies a drive voltage to the thyristor in the switching OFF period.

Abstract: In order to suppress cost of an initial investment by a user and running cost to the user to a low extent while substantially constantly maintaining an apparent illuminance, and further, to realize resource saving, in a case of using a fluorescent lamp FHF 32 as a discharge lamp La, a lamp supply power is started to be supplied from a value lower than 45 W as rated electric power at an initial period of an operation of the discharge lamp, a light adjustment signal is changed in response to an accumulated lighting time so that the lamp supply power can be a value higher than 45 W as the rated electric power on and after a rated lifetime of the discharge lamp La, whereby the lamp supply power (output of an inverter circuit 2) is adjusted.

Abstract: In order to suppress cost of an initial investment by a user and running cost to the user to a low extent while substantially constantly maintaining an apparent illuminance, and further, to realize resource saving, in a case of using a fluorescent lamp FHF 32 as a discharge lamp La, a lamp supply power is started to be supplied from a value lower than 45 W as rated electric power at an initial period of an operation of the discharge lamp, a light adjustment signal is changed in response to an accumulated lighting time so that the lamp supply power can be a value higher than 45 W as the rated electric power on and after a rated lifetime of the discharge lamp La, whereby the lamp supply power (output of an inverter circuit 2) is adjusted.