| 摘要 |
PURPOSE:To detect color shift of each plate by such an arrangement wherein original plates in which symbols for all colors are arranged are pasted to a printing plate of each color so that they perpendicularly cross with each other and distances between lines on the original plates are optically detected and memorized and the detected values of a printed sheet are compared and calculated. CONSTITUTION:Original plates 5 in which lines a-d, each representing the symbol of one color, being arranged with an equal space provided are pasted to the upper lower, left and right margins of printing plates 1-4, each representing a separated color, so that they perpendicularly cross with each other. Next, the plate 1 is set at a specified position of a detection base 6, a detection camera 7 is made to scan so that it crosses lines a-d, the distance between lines is converted into digital value and memorized as a reference value. Next, printing is performed by plates 1-4 and the distance between 4 lines at the margins of a sheet are detected by the same manner and they are compared and calculated by the previously memorized reference values and the results of the detection are converted into numerical values and they are displayed on a CRT as error data. The positional registration of plates 1-4 can be easily and accurately accomplished by adjusting the position of plates 2-4. |
