Document feeding device and image scanning apparatus

An image scanning apparatus,

• a document feeding device;
• and
• an image sensor configured to scan an image of a document sheet in transportation;
• wherein the document feeding device comprises:
• a feeding tray on which the document sheet is put;
• a lifting device configured to lift and lower the feeding tray;
• a feeding roller configured to receive contact with the document sheet and feed the document sheet;
• a sensor configured to detect that the document sheet on the feeding tray makes contact with the feeding roller;
• and
• a controller configured to control the lifting device and thereby control a height position of the feeding tray, and performs feeding and transportation of the document sheet using the feeding roller when the sensor detects that the document sheet makes contact with the feeding roller;
• wherein when the feeding and transportation of the document sheet is failed, the controller performs additional lifting of the feeding tray by a specific retry distance using the lifting device and performs feeding and transportation of the document sheet again after the additional lifting;
• and
• the retry distance is set on the basis of a type of the document sheet.