Optical device for checking a face of a blank

An optical inspection device for inspecting a face of a blank advancing past the inspection device, the optical inspection device comprising:

• a vacuum conveyor unit configured to transport the blank along a traffic path, the conveyor unit comprising
• a conveying belt having a perforated structure, a drive for moving the conveying belt, the moving conveying belt defining the traffic path of the blank,
• a suction device located and configured to flatten the blank against the conveying belt, and
• an inspection device located and configured for inspecting a first face of the blank during transportation of the blank by the vacuum conveyor unit, and the vacuum conveyor unit is located at an opposite second face of the blank from the inspection device;
• the suction device is configured to define three successive separate suction sections along the traffic path, applying suction to the conveying belt for holding the blank to a strip;
• the three further suction device sections comprising:
• a central suction section which extends opposite the inspection device, an entrance side suction section and an exit side suction section along the traffic path,
• wherein the central suction section comprises a central suction box in which a vacuum is generated and comprising at least one suction opening that leads directly to a control area,
• wherein the central suction section is between the entrance side suction section and the exit side suction section.