Sheet processing apparatus using radio signals received from wireless tags

A sheet processing apparatus for processing sheets each with a wireless tag, comprising:

• a roller through which a sheet is conveyed along a conveyance path;
• a wireless tag reader/writer configured to communicate with wireless tags;
• and
• a controller configured to:
• control the roller to convey a first sheet with a first wireless tag along the conveyance path,
• control the reader/writer to acquire a first plurality of strengths of radio signals received from the first wireless tag during the conveyance of the first sheet and a second plurality of strengths of radio signals received from wireless tags of sheets not being conveyed by the roller,
• determine a threshold value of radio signal strength for distinguishing a wireless tag of a sheet being conveyed along the conveyance path from wireless tags of sheets not being conveyed along the conveyance path based on the first plurality of strengths and the second plurality of strengths, and
• control the roller to convey a second sheet with a second wireless tag and control the reader/writer to write to the second wireless tag when a strength of a radio signal received from the second wireless tag is greater than or equal to the threshold value.