Sheet discriminator, sheet discriminating method and sheet discriminating threshold value deciding method

摘要

A sheet discriminator includes a pair of conveyor belts arranged with a specified space between them in parallel with the conveying direction in the direction orthogonal to the sheet conveying direction and put over pulleys to curve so as to hold and convey a sheet along the conveying path; a pair of reference rollers arranged between a pair of conveyor belts with a specified space in the direction orthogonal to the sheet conveying direction to hold a sheet being conveyed, and a pair of thrusting rollers arranged in contact with a pair of reference roller with the conveying path between them and thrust a sheet against the reference rollers. Further, a sheet discriminator includes a sensor roller provided between a pair of reference rollers projecting from the sheet conveying surface and moving in the direction orthogonal to the sheet conveying surface when a sheet is held and conveyed by a pair of conveyor belts, and a position sensor to detect the moving position of the sensor roller or the sheet surface position when a sheet passes the sensor roller.