Analysis and comparison Of CTP technology and CTcP technology in Corrugated Boxes of Cardboard

Jul 18, 2023

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2008 is the CTP year of the printing industry, and more and more CTP manufacturers have begun to pay attention to the upgrading of prepress platemaking equipment in the printing industry. The savvy South China East China printing giant has already fully used CTP equipment and has a clear understanding of CTP equipment, and the gradually enlightened North China printing has gradually realized the general trend of updating CTP equipment. The author has been in contact with CTP technology for a long time, and makes a brief introduction of CTP and CTcP technology that I have learned.

CTP is the abbreviation of Computer to Plate, that is, computer direct plate making technology. Since the birth of CTP, it has become the focus of attention of various industries with its superiority, but due to the restrictions of various conditions at that time, the development of computer direct platemaking technology in China is very slow, in recent years, with the gradual improvement of the functions of CTP plate materials, CTP platemaking machines and ancillary equipment, and the increasingly reasonable price, computer direct platemaking technology is developing rapidly.

CTcP is the abbreviation of Computer to Conventional Plate, which means that the computer directly makes plates on the traditional plate material. CTcP enters the printing industry with the advantage of being able to use ordinary plate materials to achieve direct plate making, which, according to its principle, is a revolutionary technology in the field of prepress plate making. Drupa 2004, BasysPrint, Esko-Graphics two companies have launched this technology molding products, basically able to solve the CTP in the process of the plate price is too high problem, is a strong competitor of CTP, but also the prepress digital plate making market appropriate supplement. In 2005, Punch Graphix, a Belgian company based in Germany that produces XEIKON digital printing equipment, invested in BasysPrint. In the same year, the factory was built in Shenzhen to assemble and produce CTcP, but after more than a year, the Shenzhen factory was withdrawn, and the domestic advantage immediately disappeared.

At present, there are more and more short version live parts in the printing market, higher and higher quality requirements, and the exchange cycle is getting shorter and shorter. However, in the traditional plate making process, there are many production links and difficult to control, and there is no efficient, high-precision, fully automated pre-press system, which can not realize the digital workflow.

CTcP can indeed image directly on the ordinary PS plate, but the plate material it uses must have higher sensitivity and resolution than the ordinary PS plate. Therefore, before investing in the printing plant, it may be appropriate to comprehensively measure the practicability of CTcP according to the actual situation of the factory (such as the amount of plate material, the type of printing business and quality requirements, etc.). CTcP is a relatively new thing, and it is not mature in terms of market testing and some performance, so users should consider whether it meets the plate making requirements of our factory before investing. Secondly, CTP technology has been very mature, printing companies in the real need of the premise, can be assured to introduce. Some experts expect that if the price of CTP plate material can be reduced to 1.5 times of ordinary plate material, basically offset with the cost of phototypesetting, film and other processes, CTP will undoubtedly have a larger market.

Here I will make a brief introduction to the main technical characteristics of CTP and CTcP:

According to the different ways of plate loading CTP can be divided into platform, internal drum and external drum.

Platform CTP can be suitable for different thickness plate, loading and unloading plate operation is relatively simple, can achieve high-speed output, compact loading and unloading, low price. However, due to the defects in geometric optics, the use of platform CTP exposure must use expensive optical correction system, and the output format is limited.

The internal drum CTP exposure retains the high quality characteristics of the film exposure machine, the CTP plate in the device is fixed, thus ensuring the stability of the plate output, compared to the platform CTP exposure machine, this structure is suitable for large format plate output, simply because the CTP plate occupies only a part of the inner surface of the drum, and there is a large opening part. This means that when the laser rotates to this section of the open part, the laser is not working, thus extending the output time and reducing the production efficiency, in order to ensure the production efficiency, it is required that the reverse mirror can do high-speed rotation, but it is easy to inhale dust when rotating at high speed, which affects the output quality, so it is necessary to filter the air in the operation room. Compared with the external drum CTP exposure machine, it has a long light path, when the reverse mirror occurs a small vibration will produce visual visible deviation, loading and unloading plate is more troublesome.

The external drum CTP exposure machine can achieve large field output, the resolution is higher than that of the platform CTP exposure machine and the internal drum CTP exposure machine, the replacement operation of the laser head is relatively simple, and the printing plate can be exposed by using multiple parallel laser beams, which can effectively shorten the output time and improve production efficiency. If the thermal plate is used, a fairly clear, almost error-free latent image can be achieved on the thermal plate. The disadvantages of external drum CTP exposure equipment are: the device cost is high, because in the exposure state, the drum of the exposure equipment to rotate, so the exposure start, stop time is relatively long, at high speed rotation, due to the role of centrifugal force, the drum will inevitably produce unwanted vibration or the phenomenon of the plate being thrown off.

Direct plate making lasers include: gas lasers (such as argon ion laser), solid lasers (such as FD-YAG), semiconductor lasers (such as LD) and so on. The laser light source used in CTP can be divided into visible light source, infrared light source and ultraviolet light source according to its spectral characteristics. Early computer plate making equipment mainly used blue (488nm), green (532nm) and red (633nm) visible lasers, now gradually replaced by infrared laser (830nm, 1064nm) and purple laser (400nm, 410nm) technology.

Of course, all kinds of products have their applicable objects, with the advantages and characteristics of CTcP, some printing companies in China can invest according to their own needs, and they are bound to appreciate the advantages of digitalization. [next]

The core of CTcP technology using traditional PS version imaging is the DMD (Digital Micro mirror Device) chip of DLP technology (Digital Lighting Progress) and the Digital Screen imaging technology DSI (Digital Screen Imaging). The number of small lenses of DMD digital micromirror determines the resolution of the device itself. Early CTcP devices used DMD digital micromirror only 1.3 million small lenses, the highest resolution can only achieve 1500dpi, although such a resolution makes the exposure speed can be guaranteed, but it can not meet some high precision print plate making. Due to the needs of the current domestic market and the continuous improvement and improvement of micro-mirror technology, the resolution of the device has also been achieved by 2400dpi, but the exposure speed is reduced as the resolution is improved. Such experimental stage products need to be further watched by the market.

DSI technology is BasysPrint's patented technology, this technology will be ultraviolet light through the DMD micromirror group reflection filter concentrated light exposure on the traditional PS plate. The light source of the CTcP device is a mercury lamp, through optical reflection and focusing, the emitted ultraviolet light (wavelength 360nm-450nm) is gathered on the digital micro mirror, the small micro mirror according to the difference between the negative image and the positive plate material, decide whether to expose and not to expose the image. Purple laser technology makes CTcP use the traditional PS version, which greatly reduces the cost of plate materials, and many manufacturers can also use the traditional pre-press process and the follow-up process of plate making.

CTcP uses the platform exposure technology, which has less error than the roller exposure technology. In addition, the driving technology is the magnetic levitation power system from German Siemens company. The magnetic levitation linear motor avoids the impact of mechanical friction and vibration on the equipment, ensures the smooth and smooth movement of the exposure head, and ensures its accuracy. The accuracy of the third generation equipment has reached ±2 microns, and the accuracy of the fourth generation equipment has been improved to ±0.3 microns, ensuring the accurate registration of the plate on the printing press.

In general, CTcP has many advantages, the most obvious is to improve production efficiency, save time and reduce production costs. However, the following issues should be noted when selecting a CTcP device:

The speed of low resolution equipment is fast, but the image quality is not guaranteed, and the speed and stability of high resolution equipment need to be considered. According to the author's previous years of CTcP equipment maintenance experience, the digital micromirror and lamp condenser reflective equipment on the environment is very high, the service life of the UV lamp will greatly affect the exposure speed, with the life of the lamp reduced, the exposure speed will be significantly reduced.

CTP and CTcP are two very broad technical topics, and the continuous development of both technologies continues to promote the improvement of the prepress process. The innovation of the two kinds of equipment has been meeting the different needs of different customers. As equipment manufacturers and suppliers can not judge the pros and cons of each other from the opposite perspective, the final choice of customers will give the answer of the market.

Note:

DLP related introduction:

DLP stands for "Digital Lighting Progress". It means digital light processing, that is, this technology must first put the image signal through digital processing, and then the light is projected. It is based on the Digital Micro mirror Device developed by Deyi Company - DMD to complete the final link of displaying digital visual information, and DMD is the abbreviation of digital micro mirror device, literally meaning digital micro mirror element. This refers to the digital micromirror wafer used in the core of the DLP technology system - the heart of the optical engine, which is a device formed on the standard semiconductor process of CMOS, plus a rotating mechanism that can adjust the reflective surface.

To be more specific, DLP projection technology is the application of digital micromirror chip (DMD) as the main key component to achieve digital optical processing. The principle is that the light source is homogenized by an Integrator, and the light is divided into R, G, and B colors through a Color ring with three primary colors (Color Wheel), and then the color is imprinted on the DMD by the lens. By synchronizing the signal method, the digital rotation of the lens signal, the continuous light into gray scale, with R, G, B three colors to show the color, and finally through the lens projection imaging.

From the technical principle of DLP, it has the following advantages:

1. Noise advantage: The inherent digital nature of DLP can make the noise disappear, because DLP has the ability to complete the last link of the digital video underlying structure, and provides a platform for the development of digital visual communication environment, DLP technology provides an achievable projection method to display digital signals, so that the full digital underlying structure is completed, with the least signal noise.

2. Accurate gray level: Its digital nature can obtain fine image quality and color reproduction with accurate digital gray level.

3. Reflection advantage: Because DMD is a reflective device, it has a light efficiency of more than 60%, making the DLP system display more efficient. This efficiency is the result of reflectivity, filling factor, diffraction efficiency, and the actual "on" time of the lens.

4. Seamless image advantage: 90% of the pixel/lens area can effectively reflect light to form a projected image. The whole array maintains the uniformity of pixel size and spacing, and does not depend on resolution. The higher the DMD fill factor gives a higher visible resolution, which, coupled with progressive scanning, creates a living projection image that is more realistic and natural than a normal projector.

5. Reliability: DMD has passed all standard semiconductor qualification tests. It has also passed obstacle tests simulating the actual operating environmental conditions of DMD, including thermal shock, temperature cycling, moisture resistance, mechanical shock, vibration and acceleration tests. Based on thousands of hours of life and environmental testing, DMD and DLP systems demonstrate inherent reliability.