1. What is CTP?

CTP has several meanings:

Computer to plate

Computer to press

Computer to paper / print

Computer to proof

CTCP (computer to conventional plate)

The CTP system discussed here is computer to plate printing technology. CTP is the computer directly to the plate, is a digital plate imaging process. CTP direct plate making machine is similar to Phototypesetter in structure and principle. The plate making equipment is directly controlled by computer, imaged by laser scanning, and then generated by developing and fixing, which can be directly printed on the machine. Computer direct plate making is to use digital workflow, directly convert text and image into digital, and directly generate plate, eliminating the material of film, the process of manual assembly, semi-automatic or full-automatic plate printing process.

2. Who and when was CTP proposed?

The concept of CTP originated from the idea of an American in 1978, but due to various reasons of technology and plate materials, CTP really developed in the 1990s. In 1995, CTP made its first large-scale debut at drupa exhibition in Germany, and then it developed rapidly.

3. What is the basis of CTP technology operation?

Digital workflow and management is the necessary condition and key of CTP technology operation. Most enterprises use standardized workflow technology to manage the prepress process, aiming at CTP output, and gradually realize digital photography, digital proofing, portable document format (PDF) output, color management, digital process management, network transmission, and finally realize the whole process digital printing market.

4. Technical characteristics of CTP

The main characteristics of CTP are as follows:

① Completely cancel the film process and corresponding materials, greatly simplify the process flow, significantly shorten the plate making time;

② It can output all kinds of plates to meet the requirements of printing machine;

③ During plate making, the plate can be accurately positioned to ensure the plate registration requirements;

④ It has high resolution and output precision of 3000-5000 DPI;

⑤ It can form 175-300lpi, 256 tone dots;

⑥ Plate making speed, in a few minutes can be made into a plate;

⑦ The four-color printing plate has good overprinter precision and can meet the printing requirements, and can prevent the moire caused by the dot shape and angle;

⑧ With good operability, it can automatically transport, automatically expose, and automatically develop, so as to ensure the accuracy of plate making;

⑨ It can produce good economic benefits.

5. Working principle of CTP technology

CTP direct plate making machine consists of three parts: precise and complex optical system, circuit system and mechanical system. A single beam of original laser produced by a laser is divided into multiple beams (usually 200-500 beams) by a multi-channel optical fiber or a complex high-speed rotating optical beam splitting system. Each beam of light is modulated by an acoustooptic modulator according to the light and dark characteristics of image information in the computer, and then becomes a controlled beam. After focusing, hundreds of microlasers are directly fired on the plate surface for CTP. After scanning the plate, the latent image of the image is formed on the plate. After display, the image information on the computer screen is restored on the printing plate for direct printing by the offset press. The diameter of each microlaser beam and the light intensity distribution shape of the beam determine the clarity and resolution of the latent image formed on the plate. The smaller the light spot is, the closer the light intensity distribution of the beam is to the rectangle (ideal case), the higher the resolution of the latent image. The scanning accuracy depends on the mechanical and electronic control part of the system. The number of laser microbeam determines the scanning time. The more the number of micro beams, the shorter the etching time. At present, the diameter of the beam has developed to 4.6 microns, which is equivalent to the printing accuracy of etching 600 LPI. The number of beams can reach 500. The etching time of a folio plate can complete the printing market in 3 minutes. On the other hand, the higher the output power and energy density of the plate beam (laser energy per unit area of paper packaging, unit: Joule / cm2), the faster the etching speed. But too high power will also reduce the working life of the laser and the distribution quality of the beam.

6. What is the basic concept of CTP system?

CTP system is composed of equipment, plate material, software and technical support, including direct plate making machine, plate making machine, printing plate, distribution software, rip, system management software, after-sales service, spare parts supply and many other aspects.

7. Classification of CTP system

The exposure system can be divided into four categories: inner drum, outer drum, flat plate and curve printing technology. Among these four types, the most commonly used are inner drum type and outer drum type; flat plate type is mainly used on large format plates such as newspapers; curve type is the least.

It can be divided into silver salt plate, thermosensitive plate (ablative thermosensitive plate, non ablative thermosensitive plate), photosensitive resin plate and polyester plate (non-metallic plate base), etc;

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

It can be divided into manual single machine, semi-automatic, full-automatic and hybrid (CTF computer to film) in terms of automation degree

From the fixed way of the plate on the drum, the connection processing can be divided into: full