The printing of network an important role, network can pass the order of image, attune level, colorific change, any reflection draft or transmission draft, all with silver particle distribution of pigment particles or the density, constitute a continuity dizzy catch tonal. This shading tonal, level must use a camera or other methods, will image segmentation greatly small outlets for their creations, show.

Is the most basic outlets plate and the structure of the unit, it for the reappearance tonal and organizational level and the role of the image outline. According to the principle of the network effect can be divided into an am and FM outlets two kinds of outlets, including the former so far by the surface very wide. Use all sorts of methods (glass nets screen, catenary screen, electric points technology) can get this type of network, and the net increase because of its simple process, quick, imaging effect the advantages and to promote the use of large scope. At the same time, people also clearly recognized its shortage, such as absolute can't eliminate turtle grain and so on, so as the printing technology development, the people started to looking to another type of network-FM outlets.

FM and network theory has produced a period of time, in early 1993, Agfa points company, Linotype-Hell company officially launched the FM and network technology, in August 1993 of Peking University in China founder also develop their own FM and network technology.

FM and network technology is the input image scanning, through the processing, through the output device to the same size of the random distribution in different space inside, the point is how many and the density of the high and low frequency appear outlets, in order to show the image of density and level of technology. Therefore, it showed images of delicate degree, no longer with each cm how many there were black and white line to explain, but with the size of the idea to define, network size is small, do image accuracy is high, the definition, the better.

The technology generated images, closer to photographic effect. For photographic process, the exposure of the intensity of different, in the same area of the particles of silver has photographic have how many different. After the enhancement, the image of the low density of place, silver particles less; The high density of place, more silver particles, density change in different regions of silver particles is how much to decide. This is similar with FM outlets, and an am different outlets, is the dot size (down) to say, therefore can not be reached almost photographic effect.

At present the company came out with network structure is different, and given a different name, such as Agfa company says "crystal nets", the Linotype-Hell company says "diamond nets", big Japanese nets screen company says "RANDOT" and so on, are in the algorithm is different, so in each image area units of the network number and printing position is different, but belong to FM and network.

FM and network of dot size, depends on the output resolution and and network parameters, such as the output resolution for the 2400 dpi, and network parameters for 2 x 2 laser point as a network, and the diameter of the son is add outlets 21 μ m; And network parameters for 3 by three laser point as a network, and the idea is for 32 μ m in diameter.

In the whole process, the key factor is the transformation of the FM and adjustment, and the core is selecting proper random rate (randomdots) and laser beam diameter are identical with each other. The resulting FM outlets to smooth solid size uniform, very few isolated spot, this is the key to the quality control. New type of satisfying the requirements phototypesetter, can press dot size to adjust the laser beam diameter. In addition, to support the next procedure, also should pay attention to selecting Dot enlargement value (Dot gain), generally can be controlled in 5% of the range. In addition, the flush of printing speed, temperature, attention such as PH value, to use the rapid high temperature of blunt, to ensure the quality of the idea. In printing, because do not exist nets Angle of FM restrictions, instead of equipment overprint precision demand is not high, of the commonly used color ink can also be accepted.

Sun edition is a easy to ignore the link, but to product quality and influencing the link. First of all, because small diameter FM outlets, don't need two exposures, otherwise screen-dot loss many, will sacrifice part of the cost of 2% or all outlets, so only USES one time exposure, shall be implemented strictly, be sure to control the time and amount of light.

On the whole, FM and an am nets compared with the following some advantages:

By random distribution network, after previously won't appear turtle lines;

Due to the large network, when printed transfer among won't because of dot enlargement to the order value big jump to change;

Detail definition effect is good, the image some fine line with nets and the formation of won't because of refraction or produce wool spine;

Can fine performance levels, suitable for high fine printing needs;

On a plate of fine needle points outlets, so the education version also subtle liquid bulk chemical, make easily offset printing operations stability;

Extremely tiny point comprehensive scattered, make the transfer and rubber cloth easy separating, reducing the transfer onto the back of dirty;

The smaller the idea, the more abundant express level.

FM and network the present problems:

Image output can not undertake repairing version;

Copying has certain difficulty;

Can't use low resolution of the site, or you will produce toothed;

As the image without set of compliance line, overprint very difficult, because the image edge profile sometimes is not clear.

Resistance to print rate is low

To solve these problems, somebody is put forward and applied FM and network and an am and network multiple and network image copy technology. The multiple and network is to solve the am traditional and network printing eligibility good but there is "turtle lines", and emerging FM and network does not appear "turtles profiling" but printing eligibility is difficult to master the contradiction between from the way and network, processed by computer in the same image in different areas and network using different way, as in the middle easy appear "turtles profiling" area USES FM and nets, highlights and dark in the area is using an am and network, so that each take its long, avoid the shorter the, the way and network will also be promoted.

At present, in the flexible printing field, FM and network technology apply more extensive, such as printing some high fine product packing box, cigarette case, believe that along with the computer technology in the field of printing thorough application, FM and network technology will also in other printing field and constantly promotion.