process and device for checking the debt claims

摘要

1297853 Photo-electric currency authentication SCHEIDT & BACHMANN GmbH 2 March 1970 [8 March 1969] 9813/70 Heading G1A In a method and apparatus for testing security papers having known areas of different light beam affecting properties, the difference in signals developed by photo-electric conversion means responsive to light reflected from or transmitted through two predetermined areas is compared with a standard value. The conversion means may comprise two photo-cells and the measurements may be made simultaneously.