Based on "CTP - computer direct plate making technology" map production process (1)

Abstract: The promotion and application of CTP computer-to-platemaking technology has enabled the idea that colorless plate-making printing has no film output and no printing loss. In China, the application of CTP technology in newspaper publishing and color packaging is not uncommon, but map production based on CTP technology is still at the initial stage. This paper expounds the working principle and features of computer-to-plate and the main advantages of map production in the computer-to-plate system. Combined with the production practice, the map production process flow based on "CTP-direct computer platemaking technology" is discussed. The article finally pointed out several issues that map production should pay attention to in the CTP technology process environment.

Keywords: direct platemaking map process

1 Introduction

Computer information technology and graphic image technology have continuously penetrated into the field of cartography. More and more new equipment, new technologies, new processes, and new materials are being used in map production, which has revolutionized map production.

In the 1980s, China promoted new technologies and materials such as “photocaching instead of lead strip”, “network film to replace film”, “film production” and “four-color subtractive printing”, which promoted the development of the map printing industry.

In the 1990s, various electronic publishing systems replaced hand-made plates more generally. Offset printing technology replaced lead-printing technologies. In particular, electronic publishing systems fundamentally removed traditional map clearing and map subdivision work and realized map design. Editing and platemaking integrated technology processing. Compared with the traditional manual drawing, the drawing accuracy and overall efficiency are greatly improved, the cost is reduced, and the map quality is also significantly improved. The realization of the integration of computer graphics and electronic publishing production systems is a major change in the field of cartography, which has produced significant social and economic benefits.

At present, computer-to-plate (CTP) technology and non-printing (digital printing) technologies are maturing, and they are entering the production and application stage, which will undoubtedly greatly promote the improvement of map product quality and the development of the map printing industry.

Since 1995, computer-to-plate technology has developed rapidly. Regardless of the plate-type, in-drum or drum-type direct platemaking technology, no matter what kind of hanging technology is used, whether it is silver salt or thermal plate, it has reached Practicality. The application of CTP technology makes the concept of colorless plate printing without film output and printing loss unrealized. It is not uncommon for its application in the field of color packaging and newspaper publishing, but it is based on the “CTP-computer-to-plate technology” map production. Still in its infancy. In order to further improve the quality of map products and enhance the level of map production services, Xi'an Coal Airline Map Printing and Printing Company implemented the CTP-computer direct plate-making technology transformation on the basis of the original electronic publishing system in 2001, in conjunction with the Yangtze River Economic Zone Sustainable Development Atlas. The large-scale atlas printing and printing projects such as “China’s Geological Atlas” and others have actively conducted technical research and production practices for map computer direct plate making, and established a more sophisticated thematic map editing and publishing process based on “CTP—Computer Direct Plate Making Technology”. , And has accumulated a certain amount of practical experience, is now a summary to communicate with their peers.

2. Working Principles and Features of Computer to Plate (CTP)

CTP technology includes: Computer to Plate, Computer to Press, Computer to Paper/Print, and Computer to Proof. It can be seen that CTP technology is a combination of prepress processing technology and output technology, which changes the traditional plate-making printing publishing process from manuscripts, films, plates, proofs to printing. This article focuses on the contents of computer-to-plate technology for reasons of space. Of course, computer-to-plate must include digital proofing content.

2.1 How Computer Directed Printing (CTP) Works

Computer-to-plate technology is a multi-disciplinary high-tech. It is a comprehensive application of disciplinary knowledge in physics, chemistry, mechanics, electronics, lasers, chemicals, computers, and typesetting software. Therefore, its technical difficulty coefficient is very high, and the structure adopted is also varied. However, from the imaging principle point of view, the principles of photophysics and photochemistry are all adopted, ie, photolithography and laser scanning are directly used for plate making.

2.1.1 Principle of photolithographic direct platemaking Photographic direct platemaking uses the principle of optical projection imaging to image an original on the surface of a photographic printing plate through an optical system, and is then developed and fixed (some plates are also washed) Printing plate.

Electrostatic photolithography Direct electrographic photolithography is the method of electrostatic imaging. After the photoconductor is exposed to light, its electrical conductivity changes to realize imaging.

The plate-making manuscript is directly imaged on a ZnO (zinc oxide) plate in a cassette through a mirror and an imaging lens under the illumination of a light source. The ZnO plate forms a high electrostatic voltage of 6000-10000 V under the action of a high-voltage power source. Under illumination, the text on the manuscript is not reflective, the corresponding ZnO plate is no light, the electrostatic potential is not changed, and the blank part of the manuscript reflects light on the plate, under the effect of light on the ZnO plate static The potential disappears, so that an electrostatic latent image is formed. After developing and fixing, a plate can be obtained. With this plate-making method, a resolution of 5 lines/mm can be obtained, which is suitable for prints having a low quality requirement and having a throughput of several hundred to several thousand.