Since the drupa printing trade show in Germany in 1995, the computer-to-plate (CTP) technology was launched. In a short time of more than ten years, the CTP system has been rapidly popularized in the world. Now, the application of the CTP system in developed countries and regions such as the United States, Western Europe, and Japan has accounted for more than 50% of all printing platemaking processes, and some places have reached 60% to 70%. By the end of 2005, more than 400 CTP systems have been put into use in China, mainly in the Yangtze River Delta, the Pearl River Delta, municipalities, and inland capital cities. The development space is very large.
First, the violet laser CTP - after the laser direct plate making star
1. Purple laser development and CTP platesetter In 1996, Nichia Corporation of Japan developed a 400-410nm InGaM crystal violet laser diode, which was originally developed to further increase the storage capacity of DVD discs. Due to its short wavelength, the light is focused. The smaller the size, the same size of the disc is 40 times more than ordinary CD, 6 to 7 times the average home DVD disc, but the laser power applied to the DVD is very small. With the continuous expansion of laser power, purple laser diodes with a lifetime of more than 3,000 hours in 1999 were introduced. In May 2000, the CTP platemaking system started using a violet laser. At the beginning, it was only 5 mW. It was only able to expose the silver salt CTP plate. In 2001, when a plate-making machine used a 15 mW violet laser, it was possible to expose high-sensitivity photopolymer plates, but the platemaking speed was slow. In 2002, the 30 mW violet laser diode appeared and was applied to the CTP platemaking system. At this time, it has been able to rapidly make plates and the advantages of the violet laser CTP plate making system have appeared. In drupa 2004, the violet laser CTP has become a big hit, and Agfa, Fuji, Heidelberg, Esko-Graphic, Escher-Grad, ECRM, Highwater, Krause and other companies have introduced violet laser CTP devices with power of 30-60 mW. After 2005, with the advent of 60 mW, 100 mW or even higher power lasers, violet laser CTP technology is even more powerful. Especially for newspapers with high requirements for plate speed and quality stability, the violet laser CTP plate making system is favored. On the other hand, the increase in the power of the platesetter will reduce the dependence on high-sensitivity CTP plates, making it possible to mass-produce medium-sensitivity violet laser CTP plates. This has also become a strong backing for the rapid promotion of violet laser CTP technology. China's surge in the installed capacity of the violet laser CTP platesetter in the newspaper industry last year also fully demonstrated that the violet laser CTP is a rising star in laser direct plate making.
2. Purple laser CTP technology features
(1) Operating environment is brighter
(2) Small laser spot, high resolution
(3) Small size, easy maintenance and replacement
(5) Stable quality
(6) long life
Second, violet laser CTP equipment
1. Equipment characteristics
Because of the small size of the laser, the violet laser CTP device usually uses an internal drum imaging structure. It is a drum that supports the printing plate, and the printing plate is fixed at a fixed position on the inner contour. During exposure, the acousto-optic modulator modulates the continuous laser beam generated by the laser light source based on the light and dark features of the image information in the computer. The modulated laser beam is first irradiated to the rotating mirror. As the mirror rotates, the laser beam is refracted onto the roller to form an exposure image. Adjust the focus can change the diameter of the laser beam, so as to obtain different degrees of resolution; adjust the speed of the mirror, you can adjust the exposure time. The advantages of this plate making method are:
(1) Scan faster. Because the violet laser is a short-wavelength laser with a wavelength of 400-410 nm, and the shorter the wavelength, the higher the energy is. Therefore, the violet laser has a higher imaging speed than other common CTP light sources such as a green laser and a red laser. The scanning speed of the violet laser can reach 55,000 lines/minute, which is equivalent to a 2400 dpi resolution to complete a split-screen scan within 1 minute and 46 seconds.
(2) Higher accuracy. The shorter wavelength light also has another characteristic, namely the laser light spot will be finer, and can scan more fine 250 lpi (1% to 98%) dot.
(3) Close to bright room operation. The violet laser plate-making system can be operated under a yellow safety light, providing the operator with a brighter working environment and making the operation more convenient.
(4) Longer life. The violet laser life of the current violet laser platemaking machine can already reach about 5 000 h. Since its working principle is start-up, it only needs to be exposed when the laser is started, usually in the closed state, without preheating stability that can produce a stable laser value, so the overall service life is longer, generally 4.5 to 5 Year (related to workload).
(5) The price is cheap. As the purple laser is also widely used in other work, such as the production of DVD discs, automobile manufacturing, etc., have a lower price. In addition, single beam laser heads can also be used, making the violet laser CTP platemaking equipment relatively inexpensive.
(6) Others. Such as the upper and lower version is convenient, can support a variety of punching specifications and so on.
2. Domestic and foreign equipment manufacturers and brands Since the introduction of the purple laser in the CTP plate-making system in May 2000, more than 20 plate-making machine manufacturers worldwide have been selling violet laser CTP platesetters to the market. At present, violet laser CTP devices commonly use violet laser diodes with power of 30 to 60 mW and a wavelength of 405 to 410 nm. Since drupa2004, models have higher precision and more types.
Table 1 lists the products and performance of the main manufacturers of violet laser CTP equipment.
Third, violet laser CTP plate
1. History of plate material development
The original violet laser was only 5mW, and it was only able to expose the silver salt CTP plate. Generally, the sensitivity of the photosensitive platen was insufficient, so the silver salt diffusion transfer plate was only available on the market. In 2001, high-sensitivity photopolymer plates could be exposed when the platesetter used a 15mW violet laser. However, this type of plate has fewer varieties and fewer manufacturers. In 2002, the 30 mW violet laser diode appeared and was applied to the CTP platemaking system. At this time, it has been able to make plates quickly. The corresponding varieties of violet laser CTP plates have been diversified. There are not only silver salt CTP plates, high sensitivity 410nm photo plates, And the medium-sensitivity photosensitive CTP plate also began to adapt to the violet laser CTP platemaking system. International media manufacturers have started to introduce their own violet laser CTP plates to the market. After 2003, with the advent of 60 mW, 100 mW or even higher power lasers, more plates will be available to meet the violet laser platemaking system. In addition, the photosensitive sensitivity is not shown in Table 2. Various purple laser CTP plates and performance are improved. The purple laser CTP plate available for users to choose on the market is very rich, lifting the user's worries.
2. Domestic and foreign media manufacturers and brands Violet laser media can be divided into silver salt version and photopolymerization version. The silver salt version contains a silver halide layer, which is diffused to form a metallic silver image area. This layer is sensitive to light and has a fast exposure. It is sufficient to use a 5 mW laser with a printing length of 350,000. The photopolymerization version utilizes free radical initiated polymerization to produce an alkali-insoluble polymer that can be developed with a water-based kit, and the waste solution does not contain silver or other potentially harmful substances. Its printing range is 200,000 to 350,000, and it can reach 1 million after baking.
Lokkai Group's second film factory, Zhongke Silver, and Shanghai Printing Technology Research Institute have all invested in scientific research and research and development of violet laser CTP plate materials. The results have been achieved, trial results are good, and mass production will soon be possible. The laser CTP plate is domestically produced, and it uses the violet laser CTP technology to paving the way for cheap media.
IV. Newspaper Industry and Purple Laser CTP
Above we talked about some features of purple laser CTP platesetter and plate material. These advantages of violet laser CTP plate making technology are exactly what the newspaper industry demands. What are the conditions for the newspaper industry to invest in violet laser CTP?
1. Mature workflow
Since the CTP technology is based on a fully digital workflow, the prepress system requires a higher level computer digital network platform. The newspaper industry must consider the following issues:
(1) It must ensure that digital technology is based on ADOBE and HARLEQUIN standards;
(2) Off-site and client network and remote control processes;
(3) PDF/JDF standard data formats and data processing types;
(4) Standard CIP3/CIP4 data control system;
(5) Fighting big version function and professional trapping function;
(6) Mature color management and digital proofing technology support.
At its core is a reliable PDF workflow, full support for PDF1.3, PDF1.4, and Postscript files, complete RIP, and PDF workflows running on the Web. Supports multiple file formats, can output curve PDF, RIP PDF , RIP Postscript and 1-bitTIFF files, but also need XML-based PDF, and support CIP3/CIP4.
2. Press printing companies' concerns
(1) Whether the workflow is accurate and safe for Chinese, is it safe, reliable, flexible, and smooth?
(2) Can the high-speed output of the plate-making machine bring about the publication's effectiveness and improve the production efficiency?
(3) Does the printing quality improve?
(4) Can new technologies and new equipment produce benefits in the short term?
(5) Is the production cost reduced?
Since the printed version must be on time, the editing system must complete editing of the layout at the scheduled output time after the deadline; the prepress department is responsible for the entire layout of the finished layout from the newspaper scheduling software output to the completion of the printing plate, in addition to the time requirements. Take care of the quality of printing. A time hurdle makes newspapers' prepress production processes different from commercial ones, although both processes use exactly the same technology, such as Postscript, PDF, RIP, and Page pairing, digital proofing, and laser photocopying. Machine and CTP direct plate making technology. The biggest difference is that the newspaper's PS/PDF file is stable, that is, from the same typesetting software, and commercial printing may come from a variety of different application software, and the stability is not well controlled. The other most important difference is the urgency of time. Commercial Printing Even if the printing press fails, it can ask for help from other printers. The problem of one day and a half is not significant. Printing in newspapers is different. If it is 5 minutes, the newspaper may be held accountable.
Therefore, newspaper printers and commercial printers have different speeds. How does the prepress process implement such an anxious time requirement? In particular, the CTP direct plate-making machine can reduce the time cost of film printing for the newspaper pre-printing process, and can transfer the CIP3 ink control data to the printing machine, which facilitates the saving of ink and paper. These benefits can play its role in the newspapers flow that counts every second.
In addition, the price of violet laser CTP equipment is relatively low, and the operation is stable and reliable. The purple laser is cheap, and replacement and maintenance are simple and convenient. The plate making speed is fast and can reach 30 to 35 frames per hour (30 mW laser), 60 to 80 frames per hour (60 mW), 200 to 250 sheets respectively. / Hour (100 mW); Plate is resistant to printing and is very suitable for newspaper industry. Violet laser plate has more room for choice, and it has already achieved localization. The price will fall to the price that the newspaper industry can afford. The laser spot is small, and the network has better reproducibility (1 % to 99%, 175 lpi). Can produce more beautiful images, improve newspaper printing quality. The following calculation is based on a set of (four sheets) 1 030mmÃ—800mm printing plate: imported violet laser CTP plate (65 yuan/m2) + digital proofing: 214+33=247 yuan film + imported PS plate (50 yuan/m2 ) + digital proofing: 105+165+33=303 yuan film + domestic PS version (3