CALIBRATION METHOD FOR AREA RATIO METER FOR PLATE PATTERN

摘要

PURPOSE:To improve the measuring accuracy of the pattern area ratio meter, by correcting the measured result of the pattern area ratio based on the distribution data of irregularity in optical reflectivity which is obtained by utilizing a non- image area in the vertical and lateraldirections of the plate. CONSTITUTION:The printing plate 20 is conveyed to the part under a photoelectric sensor 10, and linear detecting scanning is performed at this part. Gripper ends 21 and a calibration mark 23 are provided on the printing plate 20, or a solid part in the printing image part is set as the calibration mark. The non- image part 24 and the printing image part 25 are discriminated by the calibration mark 23. The photoelectric detector 13 is composed of a photodiode which performs the photoelectric transducing of the reflected light from the printing plate 20; an operation amplifier, which receives the output of the photodiode as one input; and a resistor and a capacitor which are connected across the input and output of the operation amplifier.