Digital press technology trends

A device that can accept layout information stored in digital form and implement printing is called a digital printer. Digital printing presses are divided into two types: digital printing machines with no plates and digital printing machines with plates.

One, no version of the digital press

The common feature of unprinted digital printing is the realization of variable information printing. The current non-printing press can be divided into three types of electrophotographic methods, electrocoagulation methods, and inkjet methods from a large aspect.

1. Electrophotography

First, the photoconductor (OPC) is fully charged, and then an image is taken with a laser or the like to generate an electrostatic latent image, and then the toner is covered with an electrostatic latent image, and finally the toner image is transferred onto the paper. There are two types of toner: powder and liquid. At present, powdery toner is mostly used.

Digital printers using powdered toners are the first to introduce Cromatics products. The format widths are 32cm and 50cm. The maximum length that can be output is 11m. The mechanical part of this type of press is mainly manufactured by Xeikon, such as the Xeikon DCP series. Others such as Xerox's Docucolor and 70 & 100 IBM Info 70 & l00, Nilpeter DL-3300 are also similar products. The printing machine uses electrophotographic four-color double-sided printing with a resolution of 60 Odpi. At the paper feed position of the web, the stability and transfer rate of printing can be improved by adjusting the temperature and humidity of the paper.

E-Print (Indigo) series products use liquid toner, in addition to the previous model E-Printl000, E-Print Pro, TurboStream, UltraStream, Omnius, Omnius CardPress and so on. Although the models are different, the basic structure and principle are the same. There are 800×80 Odpi and 800×12OOdpi resolutions.

2. Coagulation

The electrocoagulation digital printing machine is represented by ELCORSY TECHNOLOGY company of Monterey, Canada. This press is aimed at putting it into use after 2000. The detailed structure of the machine has not yet been announced. Figure 2 shows the mechanical operation of the ELcorsy press.

In FIG. 2, the apparatus (1) first applies a thin oily substance to the printing plate cylinder, and then, the apparatus (2) uniformly sprays a layer of ink on the oil film. The device (3) is composed of at least 3400 very thin individual needle electrodes arranged in a straight line (negative electrode), and is perpendicular to the plate cylinder. The interval between the two is about 50 μm. On the electrode, a direct current pulse in the range of 0.05-4 nm corresponding to the image signal can be generated. As shown in Fig. 3, when the electric field generated by the pulse signal reaches the plate cylinder, an electrochemical reaction occurs on the surface of the plate cylinder to generate trivalent iron ions. This iron ion enters the ink through the protective film on the surface of the roller, causing the ink to agglomerate. The stronger the signal, the more iron ions are produced, and the greater the amount of coagulated ink. Once the DC pulse signal is interrupted, all reactions will stop. The device (5) is a squeegee made of rubber. With the dry excess ink removed, in accordance with the above principles, you can form ink dots on the plate cylinder, the ink dot size and ink layer thickness and image signal has a correct correspondence.

This type of printing press is described above as a printing color group. If a plurality of groups are connected according to the necessary color number, a multicolor printing press is constructed. With the addition of an inverting device in the middle, it is possible to print on both sides, which makes it suitable for printing in various applications. Moreover, the image quality of printed matter is close to continuous adjustment of the image, and therefore, people are waiting to see how the product is listed.

3. Inkjet method

The inkjet printer is composed of a number of nozzles in a dot matrix structure. By receiving computer layout information, the ink is ejected from a very fine nozzle and the electric field is used to control the direction of the inkjet jet to generate images and graphics on the paper. There are also ink jet printers in which ink jetting and green pellet formation are achieved by means of charging and pressurizing.

Digital inkjet printers have a wide variety of uses. They include general-purpose models and special-purpose models. However, depending on the purpose of use, the speed, resolution, and color reproduction area differ greatly. In particular, it is worth noting recently that the prices of large-format, high-quality inkjet printers have fallen sharply.

Second, there are version of the digital printing machine

With digital presses, there must be preprinted plates on the plate cylinders, except that they are made directly on the press. Compared with traditional printing presses, although this type of printing press also needs a printing plate, since it is a direct plate making machine, only one printing machine can complete the production process from data to printed matter, which saves equipment. , time, materials, and reduced production costs.

l, special-purpose printing machine

The main representative model of the special-purpose stencil printer is TruePress. Its operation principle diagram is shown in Fig. 4. Its basic structure is on a four-color printing machine with a double-diameter cylinder type structure. It is equipped with Mitsubishi Silver DigiPlate for direct plate making and development. Equipment, composed of a composite structure of the printing press.

Since the Mitsubishi Silver DigiPlate plate is used, the cost is low, and various properties of the printing ink can be selected according to different needs. Therefore, the printing machine is closer to the printing conditions of the traditional printing. Moreover, this plate can use UV ink to solve a series of problems caused by the long drying time of the ink in the past printing.

In the special-purpose digital printing press, there is also a model that attracts attention. This is the Sarah/KAB's 74 Karat. The design of the double-diameter cylinder is the same as that of Screen's TruePress.

2. Traditional printing machine

The main representative model of the traditional printing press is Hyde SpeedMaster D174. This model is based on the traditional printing machine SpeedMaster 74, therefore, can use PS plate or plate making method with a resolution of 2400dpi, the plate is used by PressTek PEARLgold, and the same type of plate.

Third, future issues

The above-mentioned digital printers print the layout information in digital form. Therefore, how the network or database data is correctly transmitted to the printer is a key issue. In the entire process of data transmission, the bottleneck must be clearly identified in order to increase production efficiency. It is necessary to conduct research in the following areas in the future:
1. Digitization of the whole page of prints;
2 . Digitalization of analog negatives;
3. Electronic matching, electronic binding;
4. High-speed computing time;
5. Data processing adapted to the data volume;
6. Layout data preservation;
7. The use of the database.