The hottest interpretation of digital printing pri

2022-08-13
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Interpretation of digital printing principles (Part 2)

classification of digital printing principles

digital printing systems are mainly composed of prepress systems and digital printing machines. Some systems are also equipped with binding and cutting equipment, thus eliminating the steps of color separation, plate making, plate making, commissioning and so on. At present, digital printing machines are divided into two camps: computer to plant/CTP or direct image/DI and variable imagedigital press. In machine imaging printing refers to the process of taking the plate making directly to the printing machine, omitting the intermediate steps of plate making, film making, plate printing, plate loading, etc. it is a direct process from the computer to the printing machine; Variable data printing refers to continuous printing that requires changing the graphics and text of the printed matter (that is, the so-called data), that is, continuous printing of different graphics and text of the printed matter on the premise of uninterrupted printing process. Color digital printing machine based on powder spraying technology can be divided into production type and non production type. Production type digital printing machine has industrialized batch production capacity and high printing speed, and is suitable for long-term operation; The performance and quality of non production digital printing machine can also meet the basic requirements of printing, but the price is relatively cheap and the printing speed is slightly lower

specifically, variable data printing can be divided into the following three categories according to different imaging principles:

1 Electrophotographic: also known as xerography, it uses laser scanning to form electrostatic latent image on the photoconductor, and then uses the charge force between charged toner and electrostatic latent image to realize the latent image, which transfers the toner image to the substrate to complete printing. It is the most widely used digital printing technology

2. Ink jet printingsystem: shoot the ink from the micro nozzle to the substrate at a certain speed, and then realize the ink image reproduction through the interaction between the ink and the substrate. According to the form of inkjet, we divide it into dro on demand or impulse and continuous inkjet

3. Others: electrocoagulation, magnctography, blectron beam imaging, tonerjet

note:

1. In machine imaging Di printing machine: in essence, the offset printing machine integrates the printing plate imaging system, and the prepared printing plate can be used to print a large number of prints with the same content. The printing method is the same as that of traditional offset printing

2. Continuous inkjet: the continuous inkjet system uses pressure to make ink pass through narrow holes to form a continuous ink flow. The resulting high speed turns the ink stream into small droplets. The size and frequency of small droplets depend on the surface tension of the liquid ink, the applied pressure and the diameter of the narrow hole. When the ink drops pass through the narrow hole, they are charged to control the falling point of the ink drops. The charged ink drops repel or shift to the required position on the substrate surface through a set of charge plates. The offset of ink droplets and the position of ink dots on the surface of the substrate are determined by the charge that should be preheated for at least 15 minutes when the ink droplets leave the narrow hole

3. Dro on demand: also known as pulse ink supply, the difference between on-demand ink supply and continuous ink supply is that the pressure acting on the ink storage cartridge is not continuous, but only when there is a need for ink droplets, which is controlled by the digital electrical signal of the imaging computer. Without the offset of ink droplets, the ink tank and circulation system can be omitted, which simplifies the design and structure of the printer. The digital signal is transformed into instantaneous pressure by firmly locking the movable sand dune heating or piezoelectric crystal. Piezoelectric technology is one of the simplest ways to produce ink droplets. Using the piezoelectric effect, when the piezoelectric crystal is affected by tiny electronic pulses, it will immediately expand, so that the ink storage cartridge connected to it will be pressurized to produce ink droplets. Among them, the most representative inkjet technology belongs to piezoelectric ceramic technology

4. Electrocoagulation imaging technology: the basic principle is to condense the ink through the electrochemical reaction between the electrodes, so that the ink is fixed on the surface of the imaging drum to form an image area, while the ink in the blank area without electrochemical reaction is still in a liquid state, and then scrape the ink in the blank area through a scraper, so that only the image and text area is left on the surface of the drum, and then transfer it to the substrate through pressure, Complete the whole printing process

5. Magnetic recording digital printing machine: relying on the directional arrangement of magnetic particles of magnetic materials under the action of external magnetic field, the magnetic latent image is formed, and then the development process is completed by the interaction of magnetic force between magnetic toner and magnetic latent image, and finally the magnetic toner is transferred to the substrate. This method is generally only suitable for black-and-white images, and it is not easy to realize color images. Some of Xeikon's additives can also reduce scratches. The product is a magnetic recording digital printer with a resolution of 480dpi

6. Electrostatic imaging digital printer: use laser scanning method to form electrostatic latent image on the photoconductor, and then use the charge force between charged toner and electrostatic latent image to realize the latent image, which is used to transfer the toner image to the substrate to complete printing. This is the most widely used digital printing technology. One of the representative manufacturers adopts electronic ink development, with a resolution of 800dpi, represented by HP indigo. The other is developed with dry toner with a resolution of 600dpi, which is mainly read by Xeikon: refer to the records of fault analysis and repair in the technical archives of the tensile testing machine; Check daily inspection card, spot inspection card and regular inspection card; Check shift records and records of protection and maintenance, Xerox, Agfa, Canon, Heidelberg, Manroland, IBM and other companies

7. Electrocoagulation digital printer: the basic principle is that the ink condenses through the electrochemical reaction between the electrodes, so that the ink is fixed on the surface of the imaging drum to form an image area, while the ink in the blank area without electrochemical reaction is still in a liquid state, and then scrape the ink in the blank area through a scraper, so that only the image and text area is left on the surface of the drum, and then transfer it to the substrate through pressure, Complete the whole printing process. The representative manufacturer of electrocoagulation digital printing machine is the product of elcorsy company, with a resolution of 400DPI

author/Qiqi

source: Guangdong packaging (2005, issue 5)

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