The quality control of the printing plate in the offset printing plate of the CD (2)

Second, the control of outlets

In order to ensure the accuracy of network transfer, control bars are usually used in actual production to determine the exposure required for printing. The control strips used for printing include continuous ash grading scales, UGRA test strips, and Japanese FUJI test strips.

Here we are going to introduce the use of the continuous adjustment hairline as the exposure control strip in the usual production. Generally speaking, there are 15 grades and 21 grades for the gray ladder, with a grade difference of 0.15. That is, for each additional level, the density increases by 0.15. Indicates that the corresponding exposure will increase by 10%. If we are unable to find a negative-graded grayscale ruler, we can also use the grayscale ruler (which can be found at any printing plant or non-forest export company) to test it temporarily. However, it should be noted that in this case, the dots in the ladder should be viewed in reverse (because the grey scale for paper printing is positive and the opposite is true for the printing of the disc). That is, after labeling 95% of outlets after printing, it is necessary to observe whether the remaining 5% of the outlets can still be seen. If they can be seen, 5% of outlets are not lost. Also note that the 10% dot part can be seen if the remaining 90% of the dot prints are printed. If it can be seen, we can say that 90% of the dot prints have not been smeared. Another thing to note is that the number of lines for offset printing on paper is exactly the same as the offset number on the disc, so this method can only be used as a reference.

Of course, if the conditions permit, you can go to the film output company requirements to produce 175-line negative tone grading step (UGRA test strip, Japan's FUJI test strip is generally a few thousand dollars, and the production of negative-type continuous gray ash ladder ruler Only need one or twenty yuan). In this way, the negative grading scale can be used as the original (film) when printing, and it is closely associated with the PS plate. Determine a fixed light intensity (illuminance), adjust the length of the printing time, respectively, to test the sun. After the PS plate was developed, a half-doctor lens was used to observe the dot shift. If 2% - 3% of the outlets are not lost, more than 95% of the outlets will not be smeared. Proof of exposure is basically suitable. The exposure time and light intensity at this time can be recorded, and the printing can be performed according to this parameter in the subsequent production.

As mentioned earlier, the light source of the printing machine will decay after prolonged use. This requires that we must constantly detect and adjust the exposure of the printing machine, so that the network can be transferred within a controllable range.

Shaiban is an important process link in the offset printing of optical discs. Its quality will directly affect the production quality level of large CD players. Therefore, it must be paid attention to. At the same time, printing is a process that requires practical skills and operating experience. It requires people to understand the basic principles of the process and continuously explore it in practice. Only in this way can the best process quality be achieved in production.




Source: "Recording Media Technology"