Medium feeding apparatus, image reading apparatus, and medium feeding method

A medium feeding apparatus comprising:

• a medium mounting section forming a mounting face for mounting a medium thereon;
• a feeding roller configured to feed a lowermost medium among mediums mounted on the medium mounting section in a feeding direction;
• a movement detection unit disposed, at a position opposing the lowermost medium among the mediums mounted on the medium mounting section, upstream of the feeding roller in the feeding direction and configured to output information related to movement of the medium in a direction along the mounting face;
• and
• a control unit configured to perform abnormality detection processing for determining a feeding abnormality when movement of the medium after starting feeding the medium exceeds a permissible range based on information obtained from the movement detection unit, wherein
• a medium height detection unit that outputs information related to a height of the medium mounted on the medium mounting section from the mounting face is disposed,
• when the height is less than a first threshold value based on detection information detected by the medium height detection unit in the abnormality detection processing, the control unit continues feeding the medium regardless of detection information detected by the movement detection unit or without obtaining detection information detected by the movement detection unit,
• the first threshold value differs depending on a size of the medium in the feeding direction, and
• when a back end of the medium in the feeding direction is out of the medium mounting section, the first threshold value to be applied when the size of the medium in the feeding direction is a first size is lower than the first threshold value to be applied when the size of the medium in the feeding direction is a second size larger than the first size.

A medium feeding apparatus comprising:

• a medium mounting section forming a mounting face for mounting a medium thereon;
• feeding roller configured to feed a lowermost medium among mediums mounted on the medium mounting section in a feeding direction;
• a movement detection unit disposed, at a position opposing the lowermost medium among the mediums mounted on the medium mounting section, upstream of the feeding roller in the feeding direction and configured to output information related to movement of the medium in a direction along the mounting face;
• and
• a control unit configured to perform abnormality detection processing for determining a feeding abnormality when movement of the medium after starting feeding the medium exceeds a permissible range based on information obtained from the movement detection unit, wherein
• a medium height detection unit that outputs information related to a height of the medium mounted on the medium mounting section from the mounting face is disposed,
• when the height is less than a first threshold value based on detection information detected by the medium height unit in the abnormality detection processing, the control unit continues feeding the medium regardless of detection information detected by the movement detection unit or without obtaining detection information detected by the movement detection unit,
• the first threshold value differs depending on a size of the medium in a width direction being a direction intersecting the feeding direction, and
• the first threshold value to be applied when a size of the medium in the width direction is a first size is smaller than the first threshold value to be applied when the size of the medium in the width direction is a second size smaller than the first size.