1. Background of CTcP
Since the advent of the desktop publishing system (DTP), the printing industry has been looking for a quick and mass printing method. One solution is the direct plate-making technology for offset printing. The digital graphic information is copied onto the printing plate, which is the computer direct plate making (CTP).
Many direct plate-making equipment of CTP manufacturers use complex laser exposure technology, so new printing plates must be developed and used together, that is, CTP plates, which is a major disadvantage of the CTP process, CTP users have to give up the already familiar PS plates, instead of buying expensive CTP plates, but also to give up their familiar workflow and material properties, to adapt to a new workflow and material properties.
Computer To Conventional Plate (CTcP) is a new computer-to-plate technology developed by a foreign company. The obvious difference from CTP technology is that the two plates are different. The plate used by CTcP is the traditional PS plate, so Its emergence is a leap in direct plate-making technology and has epoch-making significance. At present, this system has sold 350 sets worldwide.
In the traditional pre-press plate-making process, the common PS plate and the plate-making negative film are in close contact with each other, and after exposure to ultraviolet light and processing, a PS plate that can be printed on the machine is obtained. The PS version can work under the conditions of the bright room, and the plate material technology is mature and the price is cheap. It has good printability and high durability when printed on the machine.
Compared with ordinary PS plates in the CTcP process, the price of CTP plates in the CTP process is expensive. In the past, China has always relied on importing CTP plates from abroad, so the price has become an obstacle for domestic printing companies to adopt CTP. The characteristic of the CTcP process is the use of low-cost conventional PS plate materials for computer direct plate making, which combines the advantages of traditional PS plate making with the advantages of digital plate making. A new direct plate making technology, CTcP, has emerged.
2. The working principle of CTcP
In the pre-press process, the digital information of graphics and text is directly imaged on a conventional printing plate that is sensitive to UV light, which is also an emerging field.
So, can the printing plate material using analog imaging technology on the plate-making machine realize digital direct imaging like CTP? The answer is yes. DSI (Digital Screening Imaging) developed by basysPrint in Germany can achieve this purpose. At the same time, the process also requires DLP technology developed by Texas Instruments.
The working principle of CTcP is as follows: In the CTcP process, UV is irradiated onto DMD (Digital Micromirror Device), there are more than 1 million micromirrors on it, and each micromirror is controlled digitally, and the UV light irradiated on its surface There are two results: UV passing through the micromirror is accepted by the optical lens system; or the micromirror deflects UV light so that the lens cannot receive UV light. This way of working shows that the micromirror is like a pixel, which forms a screened image on the printing plate. Due to the limited number of micromirrors on the DMD, the first exposure can only complete the digital image exposure of part of the image. After several consecutive exposures, the entire exposure imaging of the image is completed. The size of each exposure is about 0.8x 6.3cm. But it is closely related to the resolution of choice. The exposure head of the CTcP system is very accurate, which ensures that the image can be seamlessly stitched after several consecutive exposures, with an accuracy of 2 microns, and an exposure speed of 10 exposure images per second.
Three. CTcP imaging characteristics
CTcP has another feature. The exposure technology it uses is a very small square dot (pixel), the size of the dot is between 10-28 microns, the specific size is related to the resolution, and the edge definition of the dot obtained by the printing is excellent. In addition, the round dots of laser exposure imaging will overlap each other, and this will not happen between square dots and dots. This is an obvious advantage of CTcP technology for square dot imaging. Even with lower resolution, CTcP can be used to obtain high-quality images. For users, the benefits of using low resolution in their work are many. For example, the RIP time is significantly shortened; the amount of data processed is reduced; the memory of the computer system is saved; the exposure speed is faster. For example, the number of screens for a batch of high-n commercial printing jobs is 200 lpi, with 256 gray levels and a resolution of 1500 dpi, then the square dots are only as large as 17 microns.
Four. CTcP advantages
CTcP has many advantages, the most obvious is to improve production efficiency, save time and reduce production costs. However, the extent to which CTcP can demonstrate its advantages is also related to the printing company's mastery of digital technology. The transition from traditional plate making to computer direct plate making has many important factors in terms of time and cost.
1. PS plate can be used
There has always been a lot of controversy about various CTP plates and exposure light sources. In various CTP systems, it is inevitable to need special CTP plates, which are very expensive. The plate material used in CTcP plate making is a cheap conventional printing plate material, which is the general PS plate material used in the current process. Using CTcP can save film materials and processing materials, and save time for manual imposition.
In the workshop, because CTcP uses conventional PS plates, there is no need to add new equipment and purchase new chemicals. Everything is done according to the traditional PS plate-making process. In addition, the maintenance cost of CTcP equipment is low, because the CTcP system uses UV light for exposure imaging and can directly use the light source on the traditional plate-making machine.
2. Simple operation
It can be operated in a bright indoor environment and can easily print plates of various sizes.
3. Improve the printing quality
Many users who use CTcP have the working experience of film printing. After film is not needed, the printing quality of the printed matter has been significantly improved, because the images and dots are not affected by the quality degradation in the traditional pre-press process. After printing, the quality of the printing plate is better, because the influencing factors such as dust and scratches on the film no longer exist, and the positioning is more accurate. In short, the dots obtained by CTcP plate-making technology are the first generation dots directly transferred to the printing plate, with clean and sharp edges and faithful manuscripts.
4. Reduce printing debugging time and material loss
Since the positioning of the printing plate is not required, the quality of the printing plate is better, and there is no need to remake the plate due to inaccurate positioning, avoiding a lot of time to proofread when printing on the machine. With more and more short-form jobs in the entire printing industry, changing the plate and debugging on the machine become regular tasks, reducing the time for printing and debugging, which can significantly save time and cost. CtcP plate-making is more accurate than traditional analog plate-making, so it reduces the waste of water, paper, ink and other consumables during commissioning.
5. No need to change the current hardware configuration
CTcP can use data in 1bit / tiff format, and can use RIP data. It can use conventional developing machines and processing chemicals. It does not need a special network interface and can be networked with the existing network environment.
6. Printing customers are more satisfied
Printing customers are more satisfied with the quality of printing, and the production time of printing is shorter, which means more timely delivery, which reduces the cost of factory operations, and makes printing companies take the lead in the fierce market competition.
7. Advantages of UV plate making directly
Using 360nm-450nm UV light source exposure, which means that the conventional PS plate can be used in the direct plate-making process. This is a printing plate material used by printing companies for many years. It is familiar with its performance and processing procedures. The technology is mature, and the PS plate is more thermally sensitive. CTP plate and purple laser plate are cheaper. PS plate is the most used printing plate in the printing industry worldwide. There is no need to train printing staff because they already know the performance of this plate.
V. Principles for selection of CTcP process materials
Generally speaking, the price of UV-sensitive printing plates is cheap. Years of use have proved that this is a plate with good reliability, outstanding printing quality, and high printing durability. Compared with the newly developed CTP plate with laser exposure, CTcP means that there is no need to make any changes in the pre-press process and on-machine printing. The only requirement is to configure the UV-Setter in the system. , Low cost and unchanged process.
Most offset plates on the market can be imaged using UV-Setter exposure. In the past, users like to use negative-type regular PS (N-type PS plate) plates for digital imaging with UV light exposure. The imaging speed of this plate is very fast. Of course, the speed is also related to the size of the image area.
However, if the area of ​​the image area on the printing plate is large, it is recommended to use the positive PS version (P-type PS version) for UV exposure digital imaging. Using CTcP technology plate-making process, users can choose the appropriate plate material for different printing jobs:
1) For offset commercial printing, positive photo PS plates are used;
2) The negative PS version is suitable for sheet-fed offset printing machines;
3) The Yangtu PS version has strong chemical resistance, so it is suitable for UV ink printing, so it is resistant to UV ink corrosion and has a very high printing resistance.
For printing jobs and plate sizes, there are supporting CTcP direct plate-making machines, so it has a wide range of applications. In newspaper printing, simple relief printing and complex commercial printing, CTcP can show its talents.
Obviously, CTcP is further than CTP. Will CTcP be the terminator of CTP? It is still difficult to say that we can verify this interesting topic in the future.
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