Apparatus for inspecting can seams and the like

Apparatus for detecting an irregularity in the surface of an elongated seam having a curvate surface cross-section, said apparatus comprising:

• (a) irradiation means for irradiating said surface to produce reflected signals;
• (b) a plurality of radiation sensors, each being disposed to have a selected field of view of the surface, each such view being defined by a width extending longitudinally of said seam and a length curvately extending in a plane lying transverse to the longitudinal direction of said seam;
• each such sensor for receiving such portion of said reflected signals as are reflected within its corresponding field of view and for producing corresponding sensor output signals in response thereto;
• (c) signal processing means for receiving said sensor output signals for a succession of fields of view along the longitudinal length of said seam, and for deriving therefrom signal data representing a dimensional feature of said seam;
• and,
• (d) signal comparison means for comparing said signal data with signal data representing an acceptable dimensional limit, and for producing a rejection signal in the event that said dimensional feature does not fall within said limit.