Patent ID: 8412959

Claim:
A terminal apparatus designed as a self-powered device according to the Universal Serial Bus standard, said terminal apparatus comprising: a battery; a USB port; and a control section configured to allow relevant components of said terminal apparatus to operate on power from said battery upon power-up, said control section further notifying a host device upon connection thereto through said USB port that said terminal apparatus is a bus-powered device, in order to request a current necessary for said relevant components to operate only on the power supplied from said host device to the bus-powered device, wherein if the current necessary for operating said relevant components is not available from said host device through said USB port, then said control section causes said relevant components to operate on the power from said battery, said control section further replacing the power from said battery with the power acquired from said host device if said host device can supply the current necessary for operating said relevant components, and if the current necessary for operating said relevant components is not available from said host device upon elapse of a predetermined time period after the request for the necessary current was made, then said control section causes a display section to display a screen on which to select whether or not to acquire from said host device the current necessary for operating said relevant components, said control section further waiting continuously for the necessary current to be supplied by said host device if the necessary current is selected to be acquired from said host device by operations made on said screen, said control section further notifying said host device that said terminal apparatus is a self-powered device if the necessary current is not selected to be acquired, in order to request said host device to supply a current commensurate with the self-powered device.