Sheet feeder, laminator, image forming apparatus, and image forming system

A sheet feeder comprising:

• a sheet stacker on which sheets to be conveyed are stacked;
• a sheet feed roller configured to feed the sheets;
• a separation roller pair configured to separate the sheets fed by the sheet feed roller one by one;
• and
• a lifter configured to lift and lower the sheet stacker depending on a stack amount of the sheets,
• the sheet stacker including:
• a first stacking face opposite the sheet feed roller to support a downstream portion of the sheets in a conveyance direction;
• a second stacking face to support an upstream portion of the sheets in the conveyance direction;
• and
• a bent portion integrally connecting the first stacking face and the second stacking face such that the first stacking face and the second stacking face form a specified angle, the first stacking face having a longer length measured perpendicular to the bent portion than the second stacking face,
• the sheet stacker configured to stack the sheets such that a center of gravity of the sheets is positioned above the first stacking face, and
• the sheet stacker configured to integrally displace the first stacking face and the second stacking face when the lifter operates,
• wherein the bent portion includes a base end, and the first stacking portion is configured to rotate around the base end.