Sheet feeder and image forming apparatus

A sheet feeder comprising:

• a support to support a roll sheet winding a sheet;
• a sensor at a first position on the support, the sensor contacting a surface of the roll sheet to detect a level difference at a trailing edge of the roll sheet and output a first signal and a second signal;
• a roller at a second position different from the first position in a circumferential direction of the roll sheet on the support, the roller contacting the surface of the roll sheet to guide the roll sheet;
• and
• circuitry configured to:
• cause the roll sheet to rotate in a sheet feeding direction to feed the sheet;
• and
• detect the trailing edge of the roll sheet based on:
• the first signal output from the sensor in response to the trailing edge of the roll sheet passing over the sensor;
• and
• the second signal output from the sensor in response to the trailing edge of the roll sheet passing over the roller.