Abstract: A lighting device includes a power supplying unit that supplies power and a lighting unit operable using power supplied by power supplying unit. Power supplying unit includes: primary coil electrically connected to an output terminal of an output convertor that rectifies an alternating current supplied by an AC power source; and inverter circuit. Inverter circuit feeds to primary coil an alternating current with a determined frequency higher than a frequency of the AC power source based on an output voltage of the convertor. Lighting unit includes a secondary coil and lighting control circuit. Upon receipt of power generated by electromagnetic induction invoked by alternating current passing through primary coil in secondary coil, lighting control circuit causes an LED or other light source to emit light with power.

Abstract: A power supply unit is a power supply device that supplies power to a power reception device using electromagnetic induction. The power supply unit has a power supply coil in which planar coils that are formed by winding respective wire materials around the same point in the same plane are arranged from an inner side to an outer side in the radial direction. The power supply unit supplies alternating currents having a common frequency to respective planar coils, thereby generating a magnetic field for supplying power using electromagnetic induction in the space in which the power reception coil is arranged. A static magnetic field that is generated in the arrangement space in the case where a direct current is fed to planar coils is stronger at a position corresponding to an inner circumference of planar coil.