Patent ID: 7866666

Claim:
A processing device for reading information from media conveyed through a media transportation path according to a command from a host computer, comprising: a length detection unit that detects the length of the media; a thickness detection unit that detects the thickness and change in the thickness of the media conveyed through the media transportation path; a multifeed determination unit that detects multifeeding in which a plurality of overlapping media are conveyed together based on the detection results from the length detection unit and the thickness detection unit; and a communication unit that sends multifeed confirmation data including the multifeed determination result output by the multifeed determination unit to the host computer based on a command from the host computer; wherein the detection results include the result of detecting if the media length detected by the length detection unit exceeds a first predetermined threshold value, the result of detecting if the media thickness detected by the thickness detection unit exceeds a second predetermined threshold value, and the result of detecting if the change in the thickness of the media detected by the thickness detection unit exceeds a third predetermined threshold value.