How to increase the plate-making performance of photosensitive resin plate by flexo screening technology
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In today's fiercely competitive environment, businesses are under tremendous pressure to continuously improve the image quality of digital or traditional photosensitive resin plates. Recently, the development of screening technology can push the quality of flexographic plate making to a new stage.
One of the main limitations of flexographic printing is that all the dots of the highlights on the plate or print are not well formed. Because of the limitations of AM screening, when small dots or thin lines are applied to digital files, there is often a clear boundary between the ink layer and the blank area. In the past, people accepted it as a habit, or had to increase the color of the highlights to avoid the image's feeling of segmentation, as shown below.
One solution to these challenges is to use HybridAM hybrid AM screening technology, which increases the dot size of highlights by adding or adding colors without sacrificing image authenticity. The effect it achieves is that it can reduce or eliminate the obvious transition from the ink zone to the blank zone.
The Hybrid AM algorithm uses FM screen technology to limit the size of the dots, so as to avoid the use of tiny dots, that is, to control the tone (FM) by changing the number of dots, instead of changing the size of the dots. To control (AM).
The image below shows the concept of Hybrid AM hybrid AM screening technology. In Figure 1, the image shows a typical flexographic result, the range of tonality is compressed, and in the highlight portion, there is a very significant transition from the ink zone to the non-ink zone.
In Figure 2, by using Hybrid AM mixed AM screening, you can add minimum pips to the plate while randomly removing some pips in the highlights to avoid any unwanted colors.
Hybrid AM screening is not a new concept. However, in the past, it was not as versatile as people hoped, because the smoothness of the screen lacked realism, resulting in visible grainy and streaked highlights. The lack of realism and consistency of the network cable is due to the limitation of the amplitude modulation screen in the high-light area, and as a result, the smooth structure of the FM screening technology cannot be produced. There are several Hybrid AM screening devices on the market, but they are completely different. Although the basic principles are the same, the smoothness of the screening depends on how the screening device establishes the network cable in the highlight area.
After studying the advantages and disadvantages of different Hybrid AM algorithms, Creo believes that the use of mixed dot size can achieve more realistic reproduction, effectively eliminating inconsistencies in the highlight and transition regions. In addition, the same screening principle can also be used for the dark adjustment part to help minimize the obvious transition of the halftone part to the solid part. The traditional Hybrid AM screening uses fixed-size dots in the FM screening part of the highlight area; this leaves a small hole in the lattice of the amplitude-modulated screen, resulting in inconsistent replication and spotting.
The application of Hybrid AM in the flexo CTP workflow effectively removes the need for jump curves, and at the same time, the dot gain is minimized due to the sharp dot, which is inherent in digital plates.
Further improvements in quality can be obtained by using an element based dispensing tool. It allows you to choose Hybrid AM screening in the right place without forcing you to use it for the entire design. Another new technology is the HyperFlex (tm) screening, which complements the Hybrid AM screening.
When the photosensitive resin plate is exposed by amplitude modulation screening, the regularly arranged dots support each other in the process of forming on the printing plate, which produces an effect, which is usually called "bridge". However, when other alternative screening techniques, such as Hybrid AM screening, are employed, the number of dots in the highlight zone is reduced, thus reducing overall support. This increases the pressure on each point and affects the reproduction of the dots during development and printing.
HyperFlex screening helps the photoreceptor form small dots or image elements. As can be seen from the image below, the use of HyperFlex screening helps to improve the plate making process.
In Figure 3, we try to break the limitations of the plate making process, at 1% tone, at 120lpi Generate 25 micron dots. As you can see, the dots on the plates are not well formed, which puts a lot of risk, so that the printing effect is far less than expected.
In Figure 4, the HyperFlex screening technology is only applied in the highlight area, which helps to reduce the depth of the bumps between the dots, expands the shoulder base, enables the dots to be formed well, and obtains small dots that cannot be obtained by the prior art. Another benefit is that the surface area of the dots is constant, so the HyperFlex screening process does not cause unwanted dot gain on the print.
Figure 5 below shows the application of Hybrid AM screening on a monolithic plate with an intersection. Note that in the highlights, all the ideas are the same size, but some are isolated and unsupported. These isolated dots cannot be formed well on print.
In contrast, Figure 6 shows the same plate with HyperFlex screening. As a result, in the highlight area, the slope is shorter, and more support is provided for the isolated dots, thereby obtaining an excellent printing effect.
In short, the new digital technology continues to enhance the plate-making performance of the photosensitive resin plate. Improving Hybrid AM screening, combining Hybrid AM screening with HyperFlex screening is an example of how science and technology can be used to make flexo continue to enhance competitiveness.