Abstract: An apparatus for detecting the position of application of a sealing strip of heat-seal plastic material onto a multilayer web of packaging material for food products advanced along a predetermined path and including at least one base layer for stiffness and strength and one or more heat-seal plastic layers; the sealing strip has a first longitudinal portion, applied onto a longitudinal edge of the web, and a second longitudinal portion projecting laterally from the longitudinal edge. The apparatus comprises a light source for irradiating a transversal portion of the web during movement thereof along its path, and a sensor detecting a quantity related to different behavior of the materials forming the web and the sealing strip to light exposure and generating an output signal related to the width of the second portion of the sealing strip in a direction orthogonal to the web travelling direction and parallel to said web.

Abstract: An apparatus for detecting the position of application of a sealing strip of heat-seal plastic material onto a multilayer web of packaging material for food products advanced along a predetermined path and including at least one base layer for stiffness and strength and one or more heat-seal plastic layers; the sealing strip has a first longitudinal portion, applied onto a longitudinal edge of the web, and a second longitudinal portion projecting laterally from the longitudinal edge. The apparatus comprises a light source for irradiating a transversal portion of the web during movement thereof along its path, and a sensor detecting a quantity related to different behavior of the materials forming the web and the sealing strip to light exposure and generating an output signal related to the width of the second portion of the sealing strip in a direction orthogonal to the web travelling direction and parallel to said web.