Inspection device, packaging sheet manufacturing device, and inspection method

An inspection method used in manufacturing a packaging sheet that comprises a belt-shaped container film made of a resin and a cover film that closes a pocket in the container film, the inspection method comprising:

• an irradiation process of radiating, before content is placed into the pocket, ultraviolet light toward one face of the container film;
• an imaging process of taking images of the container film from another face side of the container film using at least two of imaging devices each disposed on respective sides of the container film in a width direction such that the pocket portion is placed between the two imaging devices;
• and
• a determination process of determining, based on the images, whether the pocket includes a pinhole, wherein
• while the container film is being conveyed along a conveyance path, the imaging process takes, with the two imaging devices, images of the pocket at a timing when the pocket portion is located:
• an upstream-side position of the conveyance path where the two imaging devices take images of an upstream-side lateral wall portion of the pocket, wherein the upstream-side lateral wall portion is located on an upstream side of the pocket along a conveying direction of the container film;
• a middle-side position of the conveyance path where the two imaging devices take images of a bottom wall portion and front-side lateral wall portions of the pocket, wherein the front-side lateral wall portions each face the respective two imaging devices in the width direction;
• and
• a downstream-side position of the conveyance path where the two imaging devices take images of a downstream-side lateral wall portion of the pocket, wherein the downstream-side lateral wall portion is located on a downstream side of pocket along the conveying direction, and
• the determination process determines whether the pocket portion includes the pinhole based on the images that are taken in the imaging process and that include information on the downstream-side lateral wall portion, the front-side lateral wall portions, the upstream-side lateral wall portion, and the bottom wall portion.