Scan assisting fixing device and scanner using the same

A scanner, comprising:

• a scanning element for selectively scanning a first object and a second object, wherein the first object comprises a first scanning portion and a first holding portion, the second object comprises a second scanning portion and a second holding portion, and a thickness of the first holding portion is not equal to that of the second holding portion;
• and
• a fixing device, comprising:
• an accommodation region for accommodating the holding portion;
• a scan window disposed in the accommodation region for accommodating the scanning portion;
• and
• a protrusion portion disposed in the scan window for positioning the scanning portion in a first direction perpendicular to the scan plane,
• wherein when the fixing device fixes the first object, the first holding portion is loaded in the accommodation region, the first scanning portion is positioned by the protrusion portion in the first direction, and a scan plane of the first object is separated from the scanning element by a first distance in the first direction;
• when the fixing device fixes the second object, the second holding portion is loaded in the accommodation region, the second scanning portion is positioned by the protrusion portion in the first direction, a scan plane of the second object is separated from the scanning element by a second distance in the first direction, and the first distance and the second distance are both within the range of a field depth of the scanning element,
• wherein the fixing device has a first casing and a second casing arranged together to form the accommodation region, the first casing has a first opening, the second casing has a second opening, and the first opening and the second opening are stacked to form the scan window.