Abstract: A defect detector for corrugated cardboard flutes comprises an optical projector for projecting to traveling flutes an inspection light having an effective line of which the length is about one pitch of flutes inclined slightly so that a tip of a normal flute is positioned on or slightly under the posterior end of the effective line and simultaneously a slope of an adjacent normal flute is positioned on the anterior end side of the effective line, an optical receiver equipped with a light-receiving element for receiving the inspection light reflected by a flute to output information according to the light-receiving position, and normal or abnormal determining means which determines that the flute height is normal if the light-receiving position detected is within an allowable range Wp.

Abstract: A defect detector for corrugated cardboard flutes comprises an optical projector for projecting to traveling flutes an inspection light having an effective line of which the length is about one pitch of flutes inclined slightly so that a tip of a normal flute is positioned on or slightly under the posterior end of the effective line and simultaneously a slope of an adjacent normal flute is positioned on the anterior end side of the effective line, an optical receiver equipped with a light-receiving element for receiving the inspection light reflected by a flute to output information according to the light-receiving position, and normal or abnormal determining means which determines that the flute height is normal if the light-receiving position detected is within an allowable range Wp.