How FAIRDOT Hybrid Screen Printing Can Achieve Color Saturation

The company purchased the software several years ago when Screen was just launched "FAIRDOT" software, and cooperated with a partner company to target high-quality printing. FAIRDOT was used in printing production. There was no printing equipment at the time. In the summer of 2002, the company purchased the KOMORI LS-440 four-color machine. Through several years of personal experience, I have some knowledge of the technical pros and cons. Based on this, we will introduce FAIRDOT.

Capture the strengths of AM and FM

First briefly introduce what is FAIRDOT. FAIRDOT is a new type of network that combines the advantages of both AM and FM screening. It can be used as a CTP-specific hybrid network. The number of corresponding network cables is 300 lpi and 400 lpi, and 400 lpi is preferred after comprehensive consideration.

As we all know, the biggest drawback of AM screening is that interference occurs between the periodicity of the image structure and the periodicity of the net, resulting in the generation of interference fringes (moiré). Even if there are no interference fringes on the input image, there are often moiré patterns appearing from the screened images, making it a headache for quality problems. The accuracy of the most commonly used network points is 175 lpi, and the resulting fine-grained images have poor performance and are prone to thread breaks or jagged lines. When using square dots on the level, tone mutations occur in the halftone dot area. This can be considered as an inherent disadvantage of the AM method.

The advantage of FM outlets is that they do not produce moiré or rose spots and they reproduce fine details. Its structural feature is to keep the size of the very fine dot evenly, and express the level by changing the number of dots. The disadvantage of FM is that the degree of density between the various outlets varies greatly and looks like a grain of sand. Moreover, even if the fine dots can be accurately recorded on the printing plate, the printing ink (image) cannot be stably transferred to the paper, and the control of the fountain solution and the ink is very difficult.

Therefore, by combining the advantages of AM and FM, we have obtained the CTP dedicated site FAIRDOT. This is a kind of network that can make use of the original production system, which can not only reduce the production efficiency, but can print high-quality products.

The elimination of moire and the presence of graininess

From the actual use of FAIRDOT experience, it is indeed possible to eliminate moire and rose spots, improve the reproduction of subtle levels, enhance color saturation, no broken lines and jagged lines, to avoid the occurrence of tune mutation - eliminating the original AM and FM There are problems.

The inadequacies are granular problems and poor highlights. The high-light part is an FM outlet, and the smallest dot generated with an accuracy of 2400 dpi is 21 μm, which makes people feel that the high-light part has a sense of emptiness and graininess. What is particularly troublesome is that even small dots that are less than 1% will be clearly imaged on the printing plate with 21μm dots, which will produce a grainy impression that will not appear in AM screening.

Although there are some problems with the structure of the highlights, there is room for improvement. From our practice, just as the vendors are proposing, the RIP and CTP used are the same as in the past, and the calculation time or additional time is not significantly different from the past. The company uses RENATUS RIP and Trueflow RIP RIP methods are no problem, before using FAIRDOT just SPM (network image storage) data installation, you can use FAIRDOT screening, it is convenient.

Temperature and humidity management is essential

Then again, even if printers can be used as they were, as advertised by manufacturers, printing equipment under a variety of conditions cannot simply be "one size fits all." To achieve "do not reduce production efficiency, use existing equipment and technologies, and obtain high-quality quality," it is necessary to do a good job of controlling and routine maintenance of the printing press related environment. In particular, the control of the fountain solution is quite strict. The control of water is more important than the control of ink, and the control of temperature and humidity is a key point in the control of water. Therefore, the control of the degree of greenhouse warming at the printing site must be absolutely consistent, and must be kept within the specified range.

In order to use FAIRDOT to achieve stable printing, the amount of fountain solution should be slightly deducted from the usual, that is, by reducing the amount required to achieve stable printing requirements. The so-called stable printing is to ensure that the ink density is maintained within the standard range by always keeping the ink thickness constant.

When deducting dampening water, care should be taken not to cause dirtiness, etc. Water roller pressure adjustment at least once a week or two times, if there is time should be adjusted daily. The wetting water also needs to be changed 1 to 2 times a week, depending on the type. The company uses ultra-pure water made from a reverse osmosis membrane-based pure water production device and uses it as a dampening water, which has a great effect on improving the stability of the fountain solution. In addition, regular roller pressure adjustment or replacement of new rollers is a recipe for more stable, high-quality prints.

Compared with the AM method, after the FAIRDOT screening method was used, the amount of ink used for printing was reduced by 20% to 30%. This is indeed confirmed in our company's printing test. In fact, the company uses Komori's KHS. After printing 30 to 60 sheets, the standard density value is reached. However, when the printing is continued to 120,000 sheets, the amount of ink on the ink roller gradually increases, and the printing density gradually increases. Big. This is just the opposite of the usual dot printing.

However, after adopting FAIRDOT outlets, the original data such as CIP3, KHS, etc. should be re-created as FAIRDOT-specific data. The reason is that FAIRDOT contains the same features as 400dpi high-precision dots. If we can do a good job in press network control, pressure control and temperature control of each roller, we can give full play to FAIRDOT's strengths and print higher quality products.

In addition, in the inter-color portion, higher color saturation can definitely be obtained as compared with AM.
(Translated by Yang Zhigang)