Double sheet detection method and apparatus of sheet-fed rotary press

摘要

A double sheet detection method and apparatus for a sheet-fed rotary press is proposed wherein a theoretical reference value is set as a difference between an intermediate value between a first theoretical amount of light transmitted through one sheet and a second theoretical amount of light transmitted through two sheets and the first theoretical amount of light; the theoretical reference value is stored in correspondence with the amount of light transmitted through a sheet; a difference is calculated between an amount of light transmitted through an nth sheet and an amount of light transmitted through an (n+1)th sheet when actual printing is performed; the theoretical reference value which corresponds to the amount of light transmitted through the nth sheet and which is defined as an actual reference value is read out; the difference calculated when actual printing is performed is compared with the actual reference value; and double sheet detection is performed in accordance with a comparison result.