Norman S. Creswick - Wyckoff NJ
Thomas J. Lipton Company - Englewood Cliffs NJ
For use with automatic machinery for packaging a food product in foil pouches and then inserting a desired number of pouches in a box, a method and apparatus for scanning the boxes to check for missing pouches. The scan is accomplished by applying like alternating magnetic fields through each box and through the foil used to make the pouches at a point upstream from where the pouches are formed. Detected field absorption associated with the upstream foil is used as a reference, and the difference between it and detected field absorption associated with a box is proportional to the number of pouches in the box. The apparatus can detect if one out of two, one out of three, or one out of four is missing, and compensates the differential signal for variations in foil thickness by multiplying the reference signal by N-1, where N is desired pouch count per box. If a pouch is missing from a box, a signal is generated which can be used to trigger a rejection mechanism to remove the short-count box.