Technology I of the most pyrographic plate imaging

2022-10-15
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Plate imaging technology (I)

CTP technology for direct imaging on a plate is divided into offline direct plate making and on-line direct plate making, namely the so-called ctplate and ctpress. The "machine" referred to here is a fingerprint brush machine. The former is a direct plate making system independent of the printing machine, which directly converts digital pages into printing plates through an independent printing plate Imagesetter, and then prints them with an ordinary printing machine. It has great versatility and flexibility, and is suitable for all kinds of printing. The latter is a direct plate making system integrating printing machine and plate making machine, which directly scans and images digital pages on the plate cylinder of the printing machine, showing the specificity of the equipment. The feature of direct plate making on the machine is that the computer completes the registration and ink volume setting at the same time during the scanning and imaging process. Therefore, it has high plate making efficiency and shorter preparation time before starting up. It is very suitable for the short plate printing market with short delivery time and variable varieties

offline direct plate making technology

(1) scanning imaging equipment

whether from the perspective of equipment or plate materials, offline direct plate making still shows a trend of diversification and serialization. The scanning mechanism of the plate imagesetter is still divided into three ways: inner drum, outer drum and platform, but the scanning light source is added to the original infrared laser IR LD (830nm), YAG (1064nm), visible light 4. Before using the equipment experiment, the laser light sources HeNe (635nm), FD YAG (532nm), Ar + (488nm) are added with ultraviolet light source

among UV light sources, there are two basic choices at present, one is UV laser diode UV LD (390 ~ 410nm), and the other is conventional high-pressure mercury lamp series (250 ~ 400nm). Uv-ld was successfully developed by a Japanese company. It is said that the service life of this solid-state laser light source has reached thousands of hours, but the power is still very small, limited to a few mw/cm2. This is also a solid-state laser source. Similar to IR-LD, there is still much room for further improvement of power. The power of IR-LD light source is increased from several mw/cm2 to several w/cm2, that is, it is increased by 1000 times, which takes less than a decade. It is estimated that the increase of uv-ld light source power will not take longer

compared with IR-LD, the most attractive aspects of uv-ld light source are (1) high optical resolution, (2) the light-emitting wavelength is in the photosensitive wavelength range of traditional photochemical photosensitive materials, and (3) low price. The characteristics of items (1) and (2) come from the short wavelength of uv-ld light source, which not only reduces the accuracy and difficulty requirements of the supporting optical system, but also eases the difficulty of plate development. There are many important factors in the traditional high sensitivity photochemistry. The color sensing range of the optical system (such as photopolymerization) can be easily adjusted to the wavelength range of 390 ~ 410nm, but it is very difficult to further red shift to 532nm (YAG laser) and 635nm (HeNe laser), and it is basically impossible to extend to 780nm (IR-LD laser). Due to these advantages of uv-ld laser, although this light source was introduced to the market in the late 1990s, it immediately received a huge response. Many famous printing plate imagesetter manufacturers, such as Agfa, Barco, Escher grad, Krause, purup eskofot, etc., carry this light source on their own devices

the key of the plate imagesetter using conventional mercury lamp light source is the scanning optical system. At present, there are dicon system (purup eskofot company) using optical waveguide and so-called "light valve technology) and UV setter system (basysprint company) using digital micro mirror chip technology (dmmc:digital micro mirror chip). Light valve technology is to guide the ultraviolet beam emitted by the conventional mercury lamp into the light valve. The light valve modulates the ultraviolet beam, controls the working state of the beam (on/off state), and then guides the modulated beam to the printing plate surface through the optical waveguide fiber to expose the printing plate. The optical fibers are arranged according to the line array, covering the whole width of the printing plate, so the main scanning does not involve any optical components. The research shows that the mechanical movement under the action of these environments greatly improves the optical scanning speed of the exposure single 1 extensive plastic granulator into a combined and intelligent plastic granulator. (to be continued)

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