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Classification and current situation: CTP introduction

what is CTP

CTP includes several meanings:

computer to plate

computer to press

computer to paper/- proof

common PS direct plate making technology, namely CTCP (computer to conventional plate)

first of all, it is clear that the CTP system discussed here is offline computer to plate. CTP is a digital printing plate imaging process from computer to printing plate. The structure and principle of CTP direct plate making machine and imagesetter are similar. Its plate making equipment is directly controlled by computers. Some users still use origin and other more professional graphics processing software for later data processing, laser scanning and imaging, and then through development and fixing, a printing plate that can be directly printed on the machine is generated. Computer direct plate making adopts digital workflow, which directly converts words and images into numbers and directly generates printing plates, eliminating the material of film, the process of manual plate making, and the semi-automatic or full-automatic plate printing process. CTP can handle a variety of printing methods, including business forms, manuals, address books, documents, finance, newspapers, labels and packaging. In addition, CTP is also suitable for printing leaflets and brochures. It is especially suitable for highly integrated front-end, creative part and back-end control circuit. It has simple structure and reliable performance. It is a closed workflow with closely combined parts. Therefore, at the same time, CTP system is particularly suitable for printing plants that completely use digital format data, such as table printing, financial printing, packaging printing and general commercial printing. For newspaper publishing, CTP can be used for newspapers that use full digital chemical sequence or pure classified advertising

why should we adopt computer direct plate making technology

market demand: there are more and more short version activities, higher and higher quality requirements, shorter and shorter delivery time, and more and more fierce price competition

the need of digital workflow: in the traditional process, there are many production links, the quality is difficult to control, the traditional printing plate has many machine adjustments, and the production efficiency of the printing machine is not high. Digital workflow cannot be realized without an efficient, high-precision, fully automated prepress system. Compared with the traditional printing process, CTP plate making process is rapidly promoted for the following reasons:

1) the delivery time is greatly shortened: the process steps are reduced a lot, the time is no longer a problem, and various short plate hardware can cope with it easily

2) stable and consistent high quality: production links are reduced, quality is easy to control, there is no point expansion, points are precise and sharp, printing density is very high, and fine printing is easily completed

3) give full play to the efficiency of the printing machine: the automatic registration adjustment of the printing plate is few, the ink on the CTP printing plate is very fast, it is easy to achieve the water ink balance, the printing preparation time is greatly reduced, the over plate paper and ink are saved, the waste is reduced, and the use efficiency of the printing machine is greatly improved

4) labor saving: in film development, manual composition, printing, revision, ink proofing

5) material saving: PS version for film, developer and ink proofing is omitted, the process is simplified, the chance of error is reduced, and redo waste is avoided. Of course, CTP currently has many shortcomings. For example, the cost of CTP system is relatively high, and most of the plates need to be introduced at present, so it is relatively expensive, which can not be accepted by small and medium-sized printing companies. The digital process of computer direct plate making system is not mature, especially the digital proofing can not fully simulate printing. Based on the shortcomings of traditional technology and the advantages of CTP direct plate making, it is necessary to adopt computer direct plate making technology

classification of CTP system

from the aspect of exposure system, it can be divided into four categories: inner drum type, outer drum type, flat plate type and curve type. In these four types, the most used are inner drum and outer drum; Flat type is mainly used for large format plates such as newspapers; Curvilinear form is rarely used. According to statistics, in 1997, among the 58 CTP machines provided by 29 manufacturers, there were 24 inner drum machines, 16 outer drum machines, 9 flat plate machines and 9 curve machines. In these forms, the external drum style gradually presents the mainstream trend

in terms of plate varieties, it can be divided into: silver salt plate, thermal plate (ablative thermal plate, non ablative thermal plate), photosensitive resin plate and polyester plate (non-metallic plate base); In terms of technology, it can be divided into: Thermal Technology (ordinary laser imaging), violet laser technology, UV light source technology

in terms of the degree of automation, it can be divided into: manual single machine, semi-automatic type, fully automatic type and hybrid type (CTF computer to film and CTP computer to plate). In terms of the fixing method of the printing plate on the drum, it can be divided into two types: full adsorption type and middle adsorption, and fixed with clips at the beginning and end. The full adsorption type has no limit on the size of the plate, while the plate used in the clip type must have a fixed size. In terms of application, it can be divided into commercial CTP system and reporting CTP system

development status of CTP system

ctp (computer to plate) technology appeared in the 1980s. This period is the initial stage of direct plate making technology research. Therefore, during this period, both technology and plate making quality are not very mature. In the 1990s, equipment manufacturers and printing manufacturers cooperated closely to accelerate the pace of research and development of this technology, and reached the level of maturity and industrial application during this period. At drupa printing exhibition in 1995, 42 CTP systems were exhibited. At drupa 2000, more than 90 manufacturers of direct plate making systems and materials from all over the world exhibited nearly 100 products. In 1996, 55.3% of the 100 largest printing enterprises in the United States adopted CTP system, and 28.8% adopted color short edition digital printing system

China uses CTP technology much later than foreign countries. In April, 1998, the Yangcheng Evening News tried the flat CTP plate making machine of AGFA company and Fang Optronics outer drum CTP in some sections of the "new Express". The first CTP computer plate making system without film in China was successfully developed in Shenyang Boji science and Technology Research Institute. This is a high-tech achievement launched by the scientific and technological personnel of the Institute after more than a year of hard work, which fills a gap in China's printing and plate making industry

CTP plate making machine, which is similar to the structural principle of Imagesetter, is no longer an obstacle to the development of CTP. One of the reasons why it cannot develop earlier and rapidly is that the corresponding process can not meet the needs in the past period of time. Digital proofing and automatic composition are the only way for the application of CTP system. If these technologies are not really solved, CTP system will not be developed. In other words, the development of CTP system is not the CTP plate making machine itself, but the process. A complete set of printing digital process from typesetting to output control is the basis of CTP system. The key to the successful implementation of CTP system is:

1. Have more than two years of experience in using postscript electronic prepress system, which can ensure that prepress technicians are familiar with basic file processing and fault inspection, and can quickly find and solve font problems, missing images and poorly structured documents

2. Half to 7. Diameter of sample holder: ф 50mm ф 60mm ф The work on 89 mm is postscript or files compatible with postscript format

3. Sufficient printing consumption: the realization of CTP system requires a certain amount of funds. The printing factory must consume a certain number of printing plates to get the corresponding return on investment

4. high quality printing plate operation: the printing factory must ensure the sustainability of printing plate quality

5. the main work is no more than 4 colors, and the printing line is lower than 175lpi

6. Have months of experience in digital proofing: digital proofing is one of the most controversial technologies in CTP workflow, because it will have an impact on customers and printing workshops. We need to train customers and printing operators in various digital proofing techniques. In addition, the success of printing is also related to the technical personnel of the company. Their technical level and learning ability directly affect the speed of CTP introduction. The company needs to carry out necessary training for such technical personnel. When the server is dealing with heavy tasks, it is very important to add system managers to ensure that the server and network can operate normally. Since CTP system affects the whole printing company, all departments involved need a series of adjustments and training

plate making machine:

in terms of plate making equipment, after several years of development, manufacturers have introduced various direct plate making systems with mature technology, which can automatically upload plates, handle different specifications and types of plates, and greatly improve the plate making speed. For example, the long-standing Quansheng 3244 series has thousands of Quansheng series computer direct manufacturing machines running successfully all over the country. It adopts a new 20 Watt thermal laser head and a unique squarespot square photosensitive imaging technology. It has won the GATF technology award of the American printing technology foundation for five times, and is well-known in the field of computer direct plate making, which has rapidly expanded to the field of digital offset printing. Built in laser cooling system and debris collection unit (it is used for ablative non flushing printing plates. It adopts the proven external drum design, and the drum rotates at a constant speed during exposure to ensure stable and consistent imaging. In order to accurately register, a unique temperature compensation system is adopted, which can adjust and compensate the heat rise and cold shrinkage of printing plates caused by changes in ambient temperature during the imaging process, ensuring that the same machine can be accurate at different times, even different printing plates Registration, stable exposure, consistent and repeatable

ctp plate material:

the key of computer direct plate making technology is to match the printing plate and imaging system. Silver salt plate: it has high sensitivity, high resolution and high printing resistance. It must be operated under the safety lamp, and the exclusion of silver salt in the process must be properly handled. Photosensitive resin plate: similar to ordinary plate, it must be treated in aqueous chemical composition. However, compared with the silver salt version, the sensitivity, resolution and printing resistance of the photosensitive resin version are very low. Using a new type of high sensitivity resin emulsion can ensure the consistency of products and the stability of graphics and texts - this is also the most important consideration when selecting plates. Mixed plate: add the low sensitivity silver halide mask layer in the exposure process to the ordinary photosensitive emulsion, so that you can get the advantages of the compromise between the two substances. However, this written program can be stored in the microcomputer, and the mixture requires a long plate making production line, two waste elimination channels, and more complex manufacturing processes. Thermal plate: it can be operated under sunlight, with high-resolution reproduction, accurate imaging and the potential to simplify the process. Plate, film and proofing can be imaged on the same instrument. However, thermal technology is not as mature as visible laser system, so thermal selection has great limitations, and thermal technology still has potential to be tapped

reprinted from: printed in China

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