Image scanner configured to detect size of original

An image scanner configured to detect a size of an original, comprising:

• a scanning unit configured to capture an image, in a main scanning direction, of the original placed on a platen, the scanning unit being movable in an auxiliary scanning direction;
• a scanning unit moving mechanism configured to move the scanning unit in the auxiliary scanning direction, a two-dimensional image of the original being scanned as the scanning unit moves in the auxiliary scanning direction with capturing the image in the main scanning direction;
• and
• an image processing unit configured to process the image of the original scanned by the scanning unit,
• the image processing unit includes:
• a candidate determining unit configured to determine at least one candidate size of the original based on a width of the original obtained by scanning a part of the image of the original at an initial position for scanning an area in the vicinity of one end, in the auxiliary scanning direction, of the original;
• and
• a scan/non-scan section determining unit configured to determine a non-scan section and a scan section in the auxiliary scanning direction based on the at least one candidate size;
• wherein the scanning unit moving mechanism moves the scanning unit at a first speed in the scan section and at a second speed, which is faster than the first speed, in the non-scan section, and
• wherein the scanning unit scans the image of the original in the scan section and does not scan the image in the non-scan section.

A method of detecting a size of an original placed on a platen of an image scanner, the scanner comprising an image scanning unit configured to scan an image of the original in a main scanning direction at a time and a scanning unit moving mechanism configured to move the image scanning unit in an auxiliary scanning direction, comprising the steps of:

• locating the scanning unit at an initial position to detect a width of the original;
• first determining at least one candidate size based on the detected width;
• second determining a non-scan section in which an end of the original would not exist and a scan section where the end of the original could exist, based on at least one candidate length corresponding to the at least one candidate size, in the auxiliary scanning direction;
• moving the scanning unit in the non-scan section at a first speed and scan section at a second speed, the first speed being faster than the second speed;
• examining whether an end of the original is detected in the scan section;
• and
• identifying that the size of the original is the candidate size corresponding to the scan section when the end of the original is detected in the scan section.