1. Field of the Invention
The invention relates to a contact-free double-sheet control device in a printing press.
2. Description of Related Art including information disclosed under 37 CFR 1.97-1.99
A double-sheet control device which operates contact-free has become known heretofore in German Published Non-prosecuted Patent Application (DE-OS) 33 44 842. This heretofore known device has two serially connected plate-like precision capacitors which are connected to one another by a bridge circuit. The precision capacitors are fastened onto a common carrier plate to compensate for operating influences, such as machine vibrations, for example, the opposing plates of the capacitors being formed by a conveyor table.
The respective serially-connected precision capacitors of the foregoing published German application, however, are only able to measure the thickness of the sheets. Consequently, a measurement is attainable only at an overlap border of two consecutive sheets. Furthermore, the spacing between two overlap borders must correspond to at least the capacitor length.