Method and apparatus for the detection of the location of multiple character marks

摘要

This invention pertains to a detection system for locating and counting identification marks attached to a written or printed item. A signal processing method and apparatus is described which allows detection of multiple character marks as a single event in continually moving linear materials. The marks are passed between the path of a detection zone comprising a light source and a photodetector to precipitate a voltage drop and feeding that drop to a circuit that recognizes the drop and simultaneously triggers a time window during which changes in voltage are ignored, which time window is no longer than the time it takes for a full mark to pass under the zone and shorter than the time it takes for the leading edge of the next multicharacter marks to reach the detection zone.