Original-feeding device

An original-feeding device comprising:

• an original tray on which a plurality of originals are stacked;
• a pickup roller configured to be lowered onto the originals on the original tray and to feed one of the originals, the pickup roller configured to be lifted up after the feeding;
• a conveyor configured to convey the original fed by the pickup roller;
• a length detector configured to detect a length of the original;
• an original sensor configured to detect a trailing edge of the original conveyed by the conveyor;
• and
• a controller configured to control the pickup roller either in a first mode in which a timing of lowering the pickup roller is determined in accordance with a length of the original detected by the length detector or in a second mode in which the timing of lowering the pickup roller is determined in accordance with a timing at which a trailing edge of the original is detected by the original sensor,
• wherein the controller changes from the first mode to the second mode if lengths of the originals detected by the length detector vary, and
• wherein, in the first mode, the controller stops conveying of the conveyor in response to the length detector detecting that the lengths of the originals vary into a smaller size.