Sheet supplier

A sheet supplier, comprising:

• a tray including a support surface configured to support a plurality of sheets;
• a sheet supply roller configured to supply, in a sheet supply direction, a first sheet which is an uppermost one of the plurality of sheets supported on the support surface by rotating about a roller shaft while the sheet supply roller is held in contact with the first sheet;
• a rotational member configured to be rotatable and to be held in contact with a second sheet which is a lowermost one of the plurality of sheets supported on the support surface in a state in which the plurality of sheets are interposed between the rotational member and the sheet supply roller;
• a presser configured to press the sheet supply roller relative to the rotational member;
• and
• a supporter including a contact portion contacting the rotational member, the supporter being configured to support the rotational member by the contact portion such that the rotational member is rotated by a movement, in the sheet supply direction, of the second sheet with which the rotational member is held in contact and to limit a movement of the rotational member caused by a force of the second sheet in the sheet supply direction;
• wherein, where a static friction coefficient between the sheet supply roller and the first sheet is defined as μ1, a static friction coefficient between the plurality of sheets supported on the support surface is defined as μ2, a static friction coefficient between the rotational member and the second sheet is defined as μ3, and a static friction coefficient between the rotational member and the contact portion of the supporter is defined as μ4, the following expressions are satisfied:
• μ1>μ4>μ2, μ3>μ4.