Inspection and sorting of glass containers

A method of sorting transparent containers having defects in the container sidewalls, which defects affect optical transmission characteristics of the container sidewalls, said method comprising the steps of:

• (a) rotating a said container about its central axis,
• (b) positioning camera means adjacent to the rotating container, said camera means including a plurality of light sensitive elements disposed in at least one linear array having a field of view parallel to said axis,
• (c) directing a first source of diffused illumination onto said container sidewall, said first source being sufficiently wide transversely of said axis that said field of view through a refractive defect in said sidewall is within said source, an opaque defect in said sidewall blocking illumination from said source to said camera means,
• (d) directing a second source of diffused illumination onto said container sidewall, said second source being sufficiently narrow transversely of said axis that said field of view through a refractive defect in said sidewall is outside of said second source,
• (e) identifying opaque defects in the container sidewall as a function of differences in illumination sensed by adjacent ones of said elements in said array from said first source,
• (f) identifying refractive defects in the container sidewall as a function of differences in illumination sensed by adjacent ones of said elements in said array from said second light source, and
• (g) rejecting a container in which either an opaque defect or a refractive defect is so identified, whereby a defective container is sorted from commercially acceptable containers.

Apparatus for detecting defects in the sidewall of transparent containers and sorting containers having such defects, comprising

• first and second light source means for providing respective first and second diffused illuminations,
• means for positioning a container adjacent to said light source means sequentially to illuminate the container sidewall,
• sensing means positioned to sense the diffused illumination provided by said light source means by viewing both said first and second source means sequentially through the illuminated container sidewall, said light source means being generally transverse to the line-of-sight of said sensing means, said first light source means being wider transversely of said line-of-sight than said second light source means and of sufficient width so that said sensing means views said first light source means when the line-of-sight of said sensing means is refracted by a defect,
• means for identifying such refractive defect in a container when the line-of-sight of said sensing means is refracted outside the width of said second light source means during said second illumination but within the width of said first light source means during said first illumination, and
• means for rejecting a container in which such refractive defect is so detected.