The appearance and maturity of CTP technology affects the research and development of DI digital printing machines (I)

introduction

Almost every drupa exhibition will introduce one or two remarkable and epoch-making new technologies. Drupa 95 introduced: digital printing and computer-to-plate technology (CTP). At Drupa 95, a total of 23 manufacturers exhibited 43 types of direct plate making equipment. On Drupa 2000, more than 90 direct plate-making systems and material manufacturers from around the world exhibited nearly 100 products. According to the statistics of the United States Printing Technology Foundation (GATF) on international major printing and publishing technologies, computer-to-plate technology ranks first for three consecutive years. In 1996, 55% of the top 100 large print companies in the United States used a direct plate system. Up to now, there are nearly 10,000 sets of direct plate-making systems installed worldwide. CTP technology has developed rapidly in foreign countries from the late 1980s to the early 1990s. The computer-to-platemaking technology is undoubtedly one of the most important concerns of the industry in the period to come. By 2004, violet lasers had occupied half of the CTP market.

However, in China, the application of computer direct plate making technology is still in its infancy. Since the introduction of CTP requires a certain amount of funds, it also requires a certain amount of technical support; moreover, because the CTP plate has to be imported at the moment, the cost is relatively expensive; digital proofing is at home, and some customers still cannot accept it. The promotion of CTP has a series of problems. China's introduction of CTP technology is relatively late. At present, it is mainly used in the printing of newspapers. The "Beijing Daily" and "Yangcheng Evening News" lead the introduction of CTP direct plate making, which solves the issue of the time of newspaper delivery. However, commercial CTP direct plate-making, China's development is not yet fast enough, there are still few commercial printing companies using computer-to-plate technology. China's domestic CTP platesetters and domestic CTP consumables have not been studied. CTPs are difficult to rapidly promote throughout the country. CTP platesetters and CTP consumables are currently important subjects studied by printing institutes and research institutes, and they are also a concern in the domestic printing industry. China's first film-free CTP computer-to-platemaking system was successfully developed at the Boji Institute of Science and Technology in Shenyang. It fills a gap in China's printing and printing industry.

At present, although there are more information on the CTP system and equipment, there are relatively few studies on the CTP process. The design of the printing process, the control and management of the printing quality are worthy of attention and need to be explored regardless of the type of printing. CTP has many advantages that traditional printing technology cannot match, but CTP still has many problems. In the case of little research on CTP process design and quality control in China, it is necessary to systematically investigate the process of CTP. There are many problems with CTP that need to be detailed and briefed, such as what is CTP? Why use CTP? What exactly is the entire process of CTP? How is it different from the traditional process? There are many varieties of CTP. What are their characteristics? What is the quality of CTP prints? What are the differences between different CTP printing proofs? This series of questions must be carefully explored.

Chapter 1 Introduction to CTP

1-1 What is CTP?

CTP includes several meanings:

Offline computer-to-plate
Machine-to-press
Direct-printing (Computer-to-paper/print)
Digital-proofing (Computer-to-proof)

Ordinary PS plate direct plate making technology, namely CTcP (Computer-to-conventional plate)
First, it is clear that the CTP system discussed here is Computer-to-plate. CTP is a computer-to-print plate that is a digital plate imaging process. The structure principle of the CTP plate-making machine and the image-setter is similar. Its plate making equipment is controlled directly by a computer, scanned and imaged with a laser, and then subjected to development and fixing to produce a printing plate directly printed on the machine. Computer direct plate making is a digital workflow that directly converts text and images into numbers and directly produces printing plates, eliminating the need for film materials, artificial imposition, semi-automatic or fully automatic printing processes.

CTP can handle a variety of printing methods, including business forms, brochures, contacts, documents, finance, newspapers, labels and packaging. In addition, CTP is also suitable for printing sheets and brochures. It is particularly suitable for closed workflows where the front-end editing, authoring and back-end production parts are tightly integrated. Therefore, at the same time, the CTP system is particularly suitable for printing plants that use digital data completely, such as form printing, financial printing, packaging printing, and general commercial printing. For newspaper publishing, CTP can be used for newspapers that use a fully digital editing process or pure classified ads.

1-2 Why Use Computer Direct Plate Making Technology

Market demand: more and more short-lived version, higher and higher quality requirements, shorter and shorter delivery times, and increasingly fierce price competition.

The need of digital workflow: In the traditional process, the quality of the production chain is difficult to control, the traditional printing plate is adjusted on the machine, and the production efficiency of the printing machine is not high. Without a high-efficiency, high-precision, fully-automated prepress system, digital workflows cannot be realized.

Compared with the traditional printing process, the rapid promotion of CTP platemaking process has the following reasons:

1) The delivery time is greatly shortened: the number of process steps is reduced, the time is not a problem, and all kinds of short-form hardware can handle it freely.

2) Stable and consistent high quality: The production process is reduced, the quality is easy to control, there are no outlets to expand, the outlets are precise and sharp, the printing density is extremely high, and fine printing is easily accomplished.

3) The efficiency of the printing press is brought into full play: few adjustments are made in the printing plate registration, and the CTP printing plate is quickly inked. It is easy to achieve the balance of ink and water, printing preparation time is greatly reduced, overprinting paper and ink are saved, and waste is reduced. The use efficiency of the press has been greatly improved.

4) Labor savings: In film development, manual imposition, printing, revision, ink proofing.

5) Consumed material savings: Eliminate the use of film, developer, and PS plate for ink proofing. The process is simplified, error opportunities are reduced, and rework is not wasted.

Of course, CTP currently has many shortcomings, such as the relatively high cost of the CTP system, and most of the current plate needs to be introduced, so more expensive, medium and small printing companies can not accept. The digital process flow of computer-to-plate systems is not yet mature, especially digital proofing cannot fully simulate printing.

Based on the many deficiencies of traditional processes and the advantages of CTP direct platemaking, the use of computer-to-plate technology is imperative.

Classification of 1-3 CTP systems

From the exposure system, it can be divided into four categories: inner drum, outer drum, flat panel, and curve. Among these four types, the most used are the inner drum type and the outer drum type; the flat type type is mainly used for large format plates such as newspapers; and the curved type is rarely used. According to statistics, of the 58 CTP machines provided by 29 manufacturers in 1997, there were 24 internal drums, 16 external drums, 9 flat plates, and 9 curved lines. In these forms, the external drum gradually shows the mainstream trend.

From the aspect of plate material, it can be divided into: silver salt plate, thermal plate (ablation type thermal plate, non-ablation type thermal plate), photosensitive resin plate and polyester plate (non-metal plate base);

From the technical aspects, it can be divided into: thermal technology (ordinary laser imaging), violet laser technology, UV light source technology;

From the degree of automation, can be divided into: manual stand-alone, semi-automatic, automatic and hybrid (CTF-computer to film and CTP-computer to plate).

From the aspect of the fixing method of the printing plate on the drum, it can be divided into: full adsorption type and middle adsorption, and two kinds of fixing are used for the first and the end. There is no limit to the size of the plate for full adsorption, and the size of the plate for the clip type must be fixed.

From the application side, it can be divided into: commercial CTP system and newspaper CTP system.

1-4 CTP system development status

CTP (Computer-To-Plate) technology appeared in the 1980s. This period is the initial stage of the study of direct plate-making technology. Therefore, during this period, neither the technology nor the quality of the platemaking industry was very mature. In the 1990s, the close cooperation between equipment manufacturers and printing manufacturers accelerated the pace of research and development of this technology, and reached a level of maturity and industrialization during this period. At the drupa printing exhibition in 1995, 42 kinds of CTP systems were exhibited. On Drupa 2000, more than 90 direct plate-making systems and material manufacturers from around the world exhibited nearly 100 products. In 1996, 55.3% of the 100 largest printing companies in the United States used CTP systems, and 28.8% used color short-run digital printing systems. China uses CTP technology much later than abroad. In April 1998, Yangcheng Evening News, Agfa's flat CTP platesetter and Fang's Optronics Drum CTP were tested in the "New Express" section.

China's first film-free CTP computer-to-platemaking system was successfully developed at the Boji Institute of Science and Technology in Shenyang. This is a high-tech achievement that the scientists and technicians have worked hard for more than a year. It fills a gap in China's printing and graphic arts industry.

The CTP plate-making machine, which is similar to the structure of the image-setter, is not an obstacle to the development of the CTP. One of the reasons why it cannot develop rapidly earlier is that the corresponding process cannot meet the needs in the past period of time. Digital proofing and automatic imposition are the only way for the application of CTP systems. If these technologies are not really solved, the CTP system will not develop. In other words, the CTP system depends not on the CTP platesetter itself but on the process. A complete graphic arts digital process from typesetting to output control is the basis of the CTP system.

The key to successfully implementing a CTP system is:

1. Having more than two years of experience in using Postscript's electronic prepress system, this experience ensures that prepress technicians are familiar with basic file processing and troubleshooting, and can quickly identify and solve font problems, missing images, and poorly constructed documents. .

2. More than half of the jobs are Postscript or files compatible with the Postscript format.

3. Adequate print consumption: A certain amount of money is required to implement a CTP system. A printing plant must consume a certain number of plates to get a corresponding return on investment.

4. High-quality printing plate operations: The printing plant must guarantee the quality of the printing plate.

5. The main work does not exceed 4 colors, and the printed cable is lower than 175 lpi.

6. Has 6-12 months of digital proofing experience: Digital proofing is one of the most controversial technologies in the CTP workflow because it has an impact on both the customer and the press shop. Customers and print operators need to be trained in various digital proofing techniques.

In addition, the success of printing is also related to the company's technical staff, their technical level and learning ability directly affect the speed of the introduction of CTP, the company needs to carry out the necessary training for such technical personnel. When the tasks handled by the server are very heavy, it is very important to increase the system administrator to ensure that the server and the network can operate normally. Since the CTP system affects the entire printing company, all departments involved need to carry out a series of adjustments and training.

Platemaker:

From the perspective of plate-making equipment, after several years of development, manufacturers have introduced a variety of direct plate-making systems with mature technologies that can automatically be printed, can deal with different sizes and different types of plates, and greatly increase platemaking speed.

Such as the prestigious Triumph 3244 series, there have been thousands of Quansheng series of computer direct machine in the successful operation of the country. Its new 20-watt thermal laser head, unique SQUARESPOT square photosensitive imaging technology. He won the GATF Technology Award from the American Printing Technology Foundation five times and enjoyed a reputation in the field of computer-to-platemaking and quickly expanded into the field of digital offset printing. Built-in laser cooling system and debris collection unit (for ablation type rinse-free plates, with a proven external drum design, the drum rotates at a constant speed during exposure, ensuring consistent imaging. For accurate registration, use A unique temperature compensation