Feeder, feeding method, and image forming apparatus

A feeder comprising:

• a feed table on which a plurality of papers are staked in one direction, wherein some of the papers are bundled by a staple;
• a take-out module configured to sequentially take out the stacked papers from an outermost surface of the papers;
• a first detector configured to detect whether or not the staple exists in the papers within a distance h measured from the outermost surface in the one direction, wherein the distance h is more than 0;
• and
• a controller configured to control the take-out module in a first mode or a second mode,
• wherein when the staple is detected in the papers within the distance h, the controller controls the take-out module in the first mode, in which the take-out module sequentially takes out the stacked papers in a first period, and
• wherein when the staple is not detected in the papers within the distance h, the controller controls the take-out module in the second mode, in which the take-out module sequentially takes out the stacked papers in a second period that is shorter than the first period.