Patent ID: 7963091

Claim:
In an indexing packaging machine comprising a main frame, a sealing station at which an upper film having a repeating pattern of printed matter on the upper face thereof is sealingly attached to a lower film, which sealing station comprises a vertically-movable lower tool and an upper tool, a sensor for sensing misalignment of the upper film relative to the lower film, and a braking mechanism for braking the upper film in order to cause the stretching of a portion of the upper film at said sealing station, the improvement comprising: said sensor comprising a video camera apparatus focused on said portion of the upper film at said sealing station for detecting a predetermined pattern-identification target on a said repeating pattern of printed matter on the upper face of the upper film, and an actuator for actuating said braking mechanism when a predetermined pattern-identification target of a said repeating pattern of printed matter has been detected by said video camera apparatus; said video camera apparatus comprising a memory and software program stored in said memory, said software program comprising a first section for storing an image of the predetermined pattern-identification target on the upper face of the upper film and a second section for producing an output signal for said actuator for braking the upper film a predetermined length of time when a predetermined pattern-identification target on a said repeating pattern of printed matter has been detected; said second section producing said output signal for said actuator of said braking mechanism for stretching said portion of the upper film an amount greater than the difference between the length of an indexing cycle and the shorter length of a said repeating pattern of printed matter on said portion of the upper face of the upper film that constitutes the upper sealing layer of a package being sealed at said sealing station, which length is taken in the longitudinal indexing direction; said software program comprising a detecting portion for detecting a predetermined pattern-identification target on the upper face of the upper film at a frequency F equal to N indexing cycles, where F is a numeral greater than one representing the frequency of detection of a predetermined target by said video camera apparatus, and N is a numerical value greater than one, whereby said video camera apparatus detects a predetermined pattern-identification target on a said repeating pattern of printed matter of said portion of the upper face of the upper once every N indexing cycles.