The Use of a Scanning Microdensitometer to Measure UPC Symbol Masters.

The printing of the UPC (Universal Product Code) symbol requires that exacting tolerances be met for bar width and color contrast variations. As the UPC symbol master is the starting point of the operation, it is a logical choice to begin the quality control procedure. The dimensions and tolerances of the symbol master are well defined, but the measurements are time-consuming and errors do occur. To eliminate these errors and reduce the time required to check a symbol master, a scanning microdensitometer interfaced to a minicomputer is being used to make the bar width measurements. With this instrument the technician is freed from making routine measurements and can devote more time to judging the overall quality of the UPC symbol master.