Patent ID: 8294910

Claim:
An image scanner comprising: a control unit configured to switch modes between a normal mode for executing an image scanning process and a power saving mode for consuming less electric power than the normal mode, depending on a predetermined condition; an original size detection unit configured to detect a size of an original; a timing detection unit configured to detect a timing for transferring the power saving mode to the normal mode; and an integrated circuit configured to allow a logic circuit to be configured in the integrated circuit based on circuit information, the integration circuit connected to the control unit, the original size detection unit, and the timing detection unit, wherein the control unit is configured to: in the normal mode, configure a normal-mode circuit in the integrated circuit, the normal mode circuit needed for the image scanning process, when transferring the normal mode to the power saving mode, configure a power-saving-mode circuit in the integrated circuit, the power-saving-mode circuit configured for communicating with the original size detection unit and with the timing detection unit during the power saving mode and being smaller in circuit size than the normal-mode circuit, and concurrently stop the original size detection unit from operating, and hold the power saving mode circuit in the integrated circuit during the power saving mode; and wherein: when transferring the power saving mode to the normal mode, the original size detection unit is configured to be activated without having to reconfigure the power-saving-mode circuit in the integrated circuit, and the control unit is configured to resupply power to and initialize the original size detection unit by communicating through the power-saving mode circuit.