APPARATUS FOR DETECTING DEFECTS ON BOTTLE MOUTH WITH SCREW THREAD

An apparatus for detecting defects on a bottle mouth having a screw thread has an illuminating unit for applying light to the mouth of a bottle under rotation; a photoelectric conversion unit for photoelectrically converting a light transmitted image of the bottle mouth illuminated with light by the illuminating unit into electric signals; a defect detecing unit for detecting a defect within a predetermined area in the light transmitted image photoelectrically converted by the photoelectric conversion unit, based on the brightness at predtermined at-least two points in a predetermined detection direction within the area; and a judge unit for calculating the number of defects detected by the defect detecting unit and judging the presence of any defect of the bottle mouth based on the number of defects. The apparatus detects defect points from the light transmitted image of the bottle mouth and judges based on the number of defect points whether or not there is a defect of a bottle.