1. Preface
Recently, with the popularity of CTP, FM screening has been paid more attention. FM screening is a screening technology developed by GerhardFischer and others in Germany in 1984. DiamondScreening was released by LinotypeHell in 1993 and published by AgfaGevaert in the name of CrystalRaster. Since then, it has also spread to Japan as a new screening method. .
GreoJapan once paid attention to the new printing performance technology, and FM screening is to accurately apply the layout to the layout with fine ideas to reproduce it is the key to the technology. However, it was at that time that the PS version had just been put on the market, and was in the transition period from the gravure plate to the PS version. There was no means to stabilize the printing plate, and this new technology was finally hindered. However, since the development of CTP, it has been possible to provide a stable printing plate, thereby reviving FM screening.
The original FM screen had 1) the obvious unevenness in the bright tone; 2) the middle tone has the ink blocking phenomenon, it is not easy to print well, and other shortcomings, often from the dissatisfaction of the printing department, these shortcomings have now been eliminated. It has become a special means of differentiated printed products and has been reassessed. At present, various high-definition screens have been published by manufacturers related to prepress engineering. The main brands of FM screens and hybrid screens that are often seen in domestic and foreign markets are listed below:
Fuji Photo Film: TAFEETA
Great Japan Screen: Fairdot / RandotX
Heidelberg: Satin
Agfa Gevaert: Subima
Kodak (Creo): Staccato
All of the above have advantages and disadvantages, but as the help of high-quality printing and high-definition printing technology, there is a great possibility of future development. Here, let's take the Staccato of Creo as the center to describe the trend of FM screening.
2. Idea construction of AM screening and FM screening
This article omits the detailed description of the principle of FM screening. After comparing AM (Amplitude Modulation) screening with the earlier FM (Frequency Modulation) screening (1st generation), a brief introduction is made to the difference between the 2nd generation Staccato .
As we all know, AM screens are dots arranged neatly, according to each dot can be 0-100% extension to express the depth. There is a regular arrangement, and households feel very equal, but this equality may cause disaster. In contrast, FM screening is based on the regular distribution of fine dots of the same size, according to their density.
At the beginning of the development, it was called the first generation of FM screening. Due to the improper distribution of ideas, the dense and scattered parts of the ideas appeared in the middle tone. This is because the uneven area of ​​the non-line part causes the fountain solution to be not evenly supplied, and ink is applied to the part with little water supply, causing ink clogging. This causes ink blocking in the middle tone, which becomes a difficult factor in printing.
The improper midtone has been improved by the second-generation FM screening represented by Staccato.
A closer look at the structure of Staccato's mid-tone ideas, it seems that the snakes are in a group to form a unique pattern. According to this pattern, the area of ​​the non-line part is uniformized, which contributes to the equal water supply, and the ink blocking phenomenon is eliminated, so that the intermediate printing is smooth.
In addition, what should be considered is the quality of FM screening, how to make homogeneous and fine ideas stably reproduced on the printing plate. This is made possible by the investment in CTP. Especially the high-performance IR laser light source called SQUAREspot installed in CTP of Creo is responsible for maintaining the high quality of Staccato.
3. Features of FM Screening
Let me introduce the specialty of FM screening that AM screening does not have. Because FM screening is based on the regular arrangement of fine dots, it has many features that make up for the improper AM screening.
Here are a few points:
1) No moiré occurs when screen-printing 2) Wide color reproduction range 3) Photographic smoothness can be expressed 4) Small colored text can be reproduced clearly 5) Hollow text in the screen is vivid 6) 4 colors Spot color effect obtained by plate-making printing 7) Less color unevenness during printing process 8) Shorter ink drying time 9) Effect of saving ink consumption
Four. Staccato's idea size and its use
Staccato can choose a variety of ideas according to different uses (see Table 1)
2400 dpi
Bright-toned idea size
Conversion of bright spots to AM points%
The number of converted AM lines in the middle tone
Staccato 10
10 m
1% 240 lpi
480 lpi
Staccato 20
20 m
1% 120 lpi or 1.5% 150 lpi
385 lpi
Staccato 25
20 m
1% 120 lpi or 1.5% 150 l pi
240 lpi
Staccato 35
30 m
1% 80 lpi or 2% 110 lpi
240 lpi
Staccato 36
30 m
1% 80 lpi or 2% 110 lpi
205 lpi
Staccato 40
40 m
2% 85 lpi
190 lpi
Staccato 70
60 m
2% 60 lpi
120 lpi
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