METHOD FOR MEASURING PRINTING SURFACE RATIO OF PRINTING MANUSCRIRT ESPECIALLY PRINTING PLATE AND ITS APPARATUS

摘要

PURPOSE: To determine percentage of the printed area to the caught whole area by spectrally evaluating each measured section of optical scanning in the measured result by a measuring head having a diffuse reflection light sensing instrument operated by spectrum. CONSTITUTION: A measuring body 3 having two light sources 9 is provided with one or plural measuring head(s) 10 between the light sources, and the head is movable for the case of a single head. The diffuse light by a diffusing plate 21 reflects on the surface of a printing plate and falls into the measuring head 10, is divided by a light divider 27, and a part reaches a photodiode 24 and the rest passes through a filter 30 and reaches a photodiode 25. A signal caught by the measuring head 10 in an instantly and locally caught measuring section 12 is expressed by vectors V, H and S in the secondary signal space. The final point of a vector considering heterogeneity is the intersection of the extended line of vector H and the extended line of the final points of vector V and vector S. The print area coverage of the measuring section 12 is calculated from this vector.