Patent ID: 7688343

Claim:
A measuring device for measuring a length of a sheet, comprising: a sheet-carrying unit configured to carry a sheet in a carrying direction; a reading unit including an area sensor and configured to repeatedly read the surface of the sheet from the leading end to the trailing end of the sheet while the sheet is being carried by the sheet-carrying unit; and a measuring unit measuring the length of the sheet in the carrying direction on the basis of information regarding the sheet surface that is repeatedly read by the reading unit, wherein the measuring unit measures a moving distance of the sheet during a time period from a preceding reading operation by the reading unit to a current reading operation by the reading unit on the basis of a comparison between the information regarding the surface of the sheet read in the current reading operation and the information regarding the surface of the sheet read in the preceding reading operation, wherein the reading unit is disposed on the carrying path, and wherein, in a case in which the reading unit includes a plurality of reading units, the measuring unit determines moving distances of the sheet based on the most frequent detecting result of the plurality of reading units.