抄録
For the purpose of determining the variations in the amounts of dampening water, ink, gum, and image materials on lithographic plates during press run, a dynamic measuring system has been constructed using infrared (IR) absorption technique. An InSb semiconductor type IR sensor combined with a semispherical thermal radiation source is brough close to the lithographic plate surface on the rotating plate cylinder at a distance of about 5mm. The sensor can be slided along the graduated bar placed in front of the press. The position along rotating direction of the plate cylinder is determined by reading the bar code strip attatched at one side of the lithographic plate. Thus the measuring position over the plate can be located by use of the bar code reader and by knowing the sensor position along the bar in front of the press. Since the response time of the InSb IR sensor used is as fast as about 1μsec, measuring is possible during the run of the press even at a speed of more than 300rpm. Using this system, the differences in water rtentivity depending on the kinds of substrates have been demonstrated.
