| 摘要 |
PURPOSE:To detect the amount of damping water regardness of the contact or separation of a watering roller and a printing plate or also of the presence of undercut portions by making up paired electrodes of a watering roller with a conductive elastic material and a water spreading roller of a conductive metal. CONSTITUTION:A brush through which voltage is supplied is contacted with the shaft of a water spreading roller 7 and also with the core metal 9 of a watering roller 8. A water-holding cover 12 is provided on the surface of conductive and insulating elastic materials 10 and 11. AC voltage is applied between paired electrodes made up of the rollers 7 and 8, and the variation in the water content of the water-holding cover 12 is detected in terms of the variation of electrical resistance values. |
