Importance

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Abstract

A method of making printing plates for color newspaper printing almost free from causing color dislocation. The present invention includes an exposure step 12 of directly drawing a desired image on a plate material E from a plate feeding step 11 by laser beam according to image drawing signals from a computer, a development and fixing step 13 of treating the exposed surface to produce a printing plate 5 with the desired image, and a bending and boring step 14 of forming bent edge stoppers 5a, 5b at the two edges of the printing plate 5 for mounting the plate 5 on the plate cylinder 4 and at least one positioning hole 5c for positioning the plate 5 on the plate cylinder 4. In the exposure step 12, pilot marks P in a desired shape are drawn near the two edges of the plate material E at the same time that a desired image T is drawn on the image drawing area Q of the plate material E according to image drawing signals from the computer. The bending and boring step 14 involves providing standard marks S having the same shape and the same positional relation as the pilot marks P above the printing plate loading table 7 of the bending and boring unit, automatically checking the superimposition between the pilot marks P on the printing plate 5 placed on the printing plate loading table 7 and the standard marks S by detection signals from an image sensor camera 19 provided above each standard mark S so that when the superimposition dislocation between the standard marks P on the printing plate 5 and the standard marks S is found to be under a set value level, at least one positioning hole 5c as well as bent edge stoppers 5a, 5b are formed at the two edges of the printing plate 5.

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First Claim