Design and Performance of an Industrial Transducer for the Offset Printing Process

Recent work in our laboratory has demonstrated the relevance of developing an opto-electronic sensor for controlling inking and wetting in a web press. We have subsequently modified this sensor to comply with specifications defined by the constrainst of the intended industrial environment. Miniaturisation, operational reliability, flexibility and modular construction were the principal concerns in this development. The result takes the form of a miniaturised measurement head that combines the pulsed light generator (diode laser), optical measurement, synchronous detection, digitalisation, and industrial standard numerical interface. Each of the small heads or units can easily be mounted on modern printing machines (which are themselves very compact) without risk of interference by parasitic light, electrical noise or mechanical vibrations, thus providing a reliable measurement up to the running speeds of today's machines (15 m/s). Each unit is connected by a numerical bus to the central processor. In this way the assembly can be adapted to the vary large variety of machine configurations that are to be controlled.