Patent ID: 8533509

Claim:
An electronic device having a shutdown mode, the electronic device being driven by power supplied from a secondary battery, comprising: a control device configured to be changeable between a normal mode while the electronic device is in the shutdown mode, and a sleep mode while the electronic device is in the shutdown mode, the normal and sleep modes both being control-device modes, with the sleep mode being a mode in which a discharging current value from the secondary battery is smaller than that of the normal mode; and a CPU section of the control device, the CPU section being stopped during the sleep mode and restored when the control device changes from the sleep mode to the normal mode; wherein the control section comprises: an acquisition section configured to acquire a remaining capacity of the secondary battery during the normal mode immediately before the sleep mode; a calculation section configured to calculate, as a restoration time from the sleep mode, a time which is shorter than a full discharge time that is required for the secondary battery to be fully discharged, by using the remaining capacity of the secondary battery acquired during the normal mode immediately before the sleep mode, and using a discharging current value from the secondary battery during the normal mode; a setting section configured to calculate the restoration time in a wake timer which functions even during the sleep mode; and an instruction section which causes the wake timer to start when changing from the normal mode to the sleep mode, performs a restoration from the sleep mode to the normal mode when the restoration time set in the wake timer is up, and instructs the acquisition section to reacquire the remaining capacity of the secondary battery.