To prevent power source efficiency from being reduced even in a normal power mode, while reducing a power source for supplying power to a load in a power saving mode.

The power supply apparatus includes: a main power source apparatus 202 operating in the normal power mode, and a night power source apparatus 201 that operates both in the normal power mode and power saving mode and has a power supply capability lower than that of the main power source apparatus 202. In the normal power mode, power is supplied from the main power source apparatus 202 to a first control section 206 and a second control section 207, and power is supplied from the night power source apparatus 201 to the second control section 207. In the power saving mode, power is not supplied from the main power source apparatus 202 to the first control section 206 and the second control section 207, and power is supplied from the night power source apparatus 201 to the second control section 207.

COPYRIGHT: (C)2010,JPO&INPIT