FM screening technology cheers

The sharpness of the printed image can be expressed quantitatively with two independent indicators, spatial resolution and pitch resolution. The resolution of image details, known as spatial resolution, is determined by the width of the screen (the amplitude modulation network) or the width of the screen (the frequency modulation network). The smaller the width, the higher the spatial resolution. Or, the more points in a unit area, the higher the spatial resolution.

The ability to appear subtle and soft when the color of the image changes, known as the tone resolution, is determined by the composition of the dots (the amplitude modulation network and the FM network) and the distribution of the dots (the frequency modulation network). For the amplitude modulation network point, when the width of the network line is the same, the smaller the exposure area of ​​the exposure light source, the higher the tone resolution. The number of toning steps in the area of ​​4 times 175 lpi equivalent dot area is as follows:

175lpi 50% dots 2540dpi 2x2 FM 10% dots 2540dpi 2x2 FM 30% dots The visual clarity of the printed image is the product of the spatial resolution and the tone resolution.

At present, a traditional view holds that the network cable frequency reaches 175 lpi and the cable width is 145 μm, which is equivalent to the limit of human visual resolution at a distance of 40 cm from the print. If the network cable frequency continues to increase, people will not feel the improvement of the print definition, only Can increase costs in vain. This view created confusion in the printing industry and often led companies to abandon their efforts to improve the clarity of print. Through actual observation and analysis, it is known that the roughness of the AM web print is mainly caused by the “rose spot” produced by multi-color printing. The roughness of the FM network prints is mainly caused by the monochrome version of "freckle".

Under normal circumstances, the width of the "rose spot" is several times the width of the cable. In the area where the three-color ink overprint color tone value is midtone, the "rose spot" can be clearly seen, and the printed image appears rough. , color lacks luster. Therefore, the use of amplitude modulation netting and screen printing to reduce the size of "rose spots" has become a necessary measure to improve the clarity of prints.

The PS resolution of printing applications, the printability of the ink, and the printability of the substrate limit the number of screens. Under the condition of the existing printing materials, the quality of the products can be kept stable by using a 350 lpi screened printing product. In high-definition printing technology, the method of improving spatial resolution is relatively simple. As long as there are corresponding network cable settings in RIP, and the corresponding output linear adjustment can be basically satisfied. It should be noted that the width of the edge of the film web site should be as small as possible, which has stringent requirements for focusing laser beam focusing, film sensitivity, and development conditions.





Source: PACK.CN