Patent ID: 6242733
Filing Date: 2001-06-05
Classification: B65H,G07D

Abstract:
Apparatus for distinguishing single sheets from multiple sheets in a sheet path, comprising:a first radiation source positioned on a first side of the sheet path, wherein the radiation source emits radiation substantially only during first periodic intervals, and wherein radiation from the first radiation source is directed to impinge on a sheet in the sheet path;a first detector, wherein the first detector is positioned to sense radiation from the first radiation source that is either reflected by or transmitted through a sheet in the sheet path, and wherein the first detector is operative to generate first signals responsive to radiation sensed;a first signal conditioner in operative connection with the first signals, wherein the first signal conditioner is operative to generate a first output responsive to the first signals generated substantially during only the first periodic intervals; anda comparator in operative connection with the first signal conditioner, wherein the comparator is operative to compare a first sensed value and a threshold, wherein the relationship of the sensed value and the threshold varies responsive to the first output, whereby the relationship of the sensed value to the threshold is indicative of whether a detected sheet is a single or multiple sheet.