POWER SUPPLY DEVICE, ELECTRICAL APPARATUS, COMPUTER DEVICE AND POWER SUPPLY METHOD

摘要

PROBLEM TO BE SOLVED: To significantly reduce the power loss in the power supply off or light load of an electronic apparatus having a power source part such as AC adaptor connected thereto. SOLUTION: This device comprises an AC adaptor 10 for supplying an external power to a system 30, a battery 20 to be on the basis of the power supplied from the AC adaptor 10 and also supply the charged power to the system 30 by discharging the power; and a controller 31 for controlling the supply of power from the AC adaptor 10 and battery 20 to the system 30. When the system 30 is in power supply off or light load in the state where the AC adaptor 10 is connected to the system 30, the controller 31 stops the supply of power from the AC adaptor 10 to the system 30 to supply the power from the battery 20.