METHODS state, QUALITY OR PASSER CONTROL OF OPTICAL SICHERHEITSMERKMALENAUF SECURITIES, IN PARTICULAR BANK NOTES, AND DEVICE FOR IMPLEMENTING THE PROCESS

摘要

Optical security features, e.g. in the form of metallic reflecting layers, in bank notes 3 or the like are checked by moving the bank notes using transport belts 4 past a light source 1, preferably infrared operating between 800-1000nm and having a cylindrical lens 6, on one side of the bank note and scanning the security feature by means of an electronic camera 2, preferably a CCD-Line-Scan, on the other side of the bank note. The values measured by the camera relating to the intensity and distribution of the light passing through the bank note and through or around the security feature are compared with desired values to produce an indication of the quality or condition of the security feature. The axes of the light source and camera are inclined by an angle differing from 180{ so that no light is directly incident on the detecting element of the camera.