Sheet feeder and image forming apparatus

An image forming apparatus comprising:

• an image forming unit configured to form an image on a recording sheet;
• and
• a sheet feeder configured to feed the recording sheet to the image forming unit, the sheet feeder comprising:
• a casing having a loading surface on which a plurality of recording sheets are to be loaded;
• a supply roller configured to feed the recording sheets loaded on the loading surface toward the image forming unit;
• a drive mechanism configured to move the supply roller;
• a blocking member disposed upstream from the supply roller in a sheet feed direction, the blocking member including a block surface configured to be moved between a first position where the block surface is separated a first distance away from the loading surface and a second position where the block surface is separated a second distance away from the loading surface, the first distance being smaller than the second distance, the block surface being configured to block insertion of a recording sheet located at a distance greater than the first distance from the loading surface to a downstream side in the sheet feed direction when the block surface is in the first position, the block surface being configured to allow insertion of the recording sheets located within the first distance from the loading surface to the downstream side in the sheet feed direction when the block surface is in the first position;
• and
• an interlocking mechanism configured to receive a drive force from the drive mechanism to move the blocking member.