Patent ID: 8786865

Claim:
An asperity detection device for an aluminum can which detects asperity of the aluminum can at a top surface of a mouth section during single-row conveyance, the can having the mouth section in which a curl portion is formed by curling an aperture end of the mouth section outward so that a cap with liner is attached to the mouth section, comprising: first lighting devices which irradiate a first light horizontal to the top surface of the mouth section from a side of the aluminum can; a second lighting device which irradiates a second light vertical to the top surface of the mouth section from above the aluminum can; and an imaging device which is arranged above the aluminum can, photographs the top surface of the mouth section, and detects reflection at the top surface, wherein three or more first lighting devices are arranged with even intervals in a circumferential direction around a periphery of the mouth section so as to irradiate the first light to the top surface from a side of the mouth section along tangent lines of a cylindrical surface of the mouth section horizontal so that each of optical axes of the first light does not coincide with another optical axes of the first light and each of irradiation positions of the first light is shifted from another irradiation positions of the first light.