Introduction to Electromagnetic Printing

Introduction to Electromagnetic Printing
Electromagnetic printing was the main application technology for the Nipson press. It was invented by Bull in 1980 and commercialized in 1984. This printing technology consists of an array of tiny electromagnetic recording write heads, which produces a magnetic latent image on the surface of a hard metal roller. After that, it is developed with a magnetic toner. The toner absorbs ink on the magnetic latent image, and the ink is pressurized. After being transferred to the paper surface, it is heat-fixed to create a fixed image. This printing technology is a brand-new application technology for the printing industry.
First, the printing engine The printing engine is composed of several simple and reliable subsystems. The basic body of the engine is the drum, which is based on hard metal and is similar to the application of photocopying technology. The other subsystem is similar in function to other non-contact technologies, but its structure is actually quite different. The surface structure of the printing cylinder is a layer of electromagnetic hard layer. Electromagnetic is placed on magnetically soft material with a magnetic strength of about 500 oerst.
In fact, the mechanical resistance of the drum surface is quite strong without the use of a soft coating. The life of the drum is over 15 million feet long.
Electromagnetism printing can match different image lengths to meet the needs of printing applications without changing the diameter of the cylinder. It only needs to increase the speed of the printing engine.
The magnetic afterimage on the drum can be degaussed by the elimination bar each time it is rotated so that the drum can continue to receive new magnetic images.
Second, recording head The image recording station contains an array of electromagnetic recording write head, axially parallel to the drum, and its processing process is similar to the recording head of the disk drive in the computer, but designed specifically for electromagnetic printing applications. The first-generation recording heads used in the early days were used for vertical recording, and the coils did not change during operation. Therefore, the lower drive currents can be used in the range of about 100 - 150 microamperes, resulting in higher magnetic efficiency. Can make the lateral density higher. It is impossible to use a traditional recording and writing structure. The recording head has a density of 240 poles per inch to form 336 poles per square. The development of electronics has made the recording heads of second-generation electromagnetic printers better, that is, in order to exceed 240 dpi currently used, it is necessary to consider the use of collective recording and writing components, combined with standard silicon micro-electrochemical treatment and silicon electrochemical precipitation, so that magnetic collection With the electromagnetic microstructure becomes possible. The electromagnetic silicon recording head includes a one-inch square silicon chip. The recording head is a high-density array recording electromagnetic, which is positioned by a diode matrix on the chip. This new recording head allows for higher print quality, better stability, and higher speed recording heads.
The function of the electromagnetic recording and writing head is similar to the imaging effect of the reflected beam in the laser copier, the light emitting diode in electrophotography, or the ion card sandwiched in the electron beam.
3. After the latent image and image recording head are opened, a magnetic dot is written on the surface of the drum. Each magnetic dot forms a permanent magnetic field and forms a latent image. The external magnetic field around the drum surface image is very low (about 100 to 200 oersted ), however, the magnetic field shows a particularly high sharpness, the important factor being due to the use of toner for imaging.
The main advantage of electromagnetography is the permanent image. Many images can be printed after the image is produced without rewriting. In fact, once recorded on the roller, it can be maintained for a long time without magnetic interference. This feature is related to other non-contact printing technologies. different places. As the drum rotates past the development station, a single group of toner particles is adsorbed on the magnetic image, which can reduce many of the problems associated with conventional two-group toners. Og, if necessary, supervise the concentration of toner added to the spreader. Actually, in the past, to eliminate the problem of a single group of toners, after the image is developed, a vacuum knife or a trimming pinhole is used to remove it, so that the excess toner can be removed and a more sharp image can be formed.
IV. Image Transfer Image transfer is based on 60% mechanical pressure and 40% static electricity, and the resulting transfer efficiency is about 80-85%. The use of electrostatic electricity in certain respects is quite related to the humidity of the air. If you want to get the ideal transfer, the surface layer of the printed material must not have too high humidity. If the toner resistance is about 103 W/cm, and the electrical conductor is charged The voltage is 500 - 1000 V, and the selected concentration is 1.1 to maintain the resistance at 1012 W/cm. If the toner is charged first, the selected value of 1.3 and 1.1 will reduce the resistance of the paper to 1010 W/cm.
5. Image fixation The method of image fixation is the same as that of any dry powder printing technology except that it is dried at a high speed. Fixing requires the use of radiant heat or a xenon flash to turn the toner into a semi-liquid state. In the low-speed device, the heating roller can be used, and in the magnetic printer, radiant heat is used to fix the image. In recent years, the flash-fixing method has been cited, which has the advantages of significantly lowering the paper surface temperature and also reducing many problems caused by heat, such as reduced heat energy consumption, maintenance fees, and the like. The next processing unit on the drum is the cleaning station, which removes the remaining toner that has not been transferred to the paper on the drum. In fact, the toner is sucked into the bottle using a steel roll with a scraper and a vacuum suction device.
The last step is to remove the magnetic image on the drum, that is, to use a low voltage wiper to replace the bulb in the electronic copying machine and the high voltage pre-charged toroidal discharge wire.
Sixth, the commercial application of electromagnetic printing The electromagnetic printing machine can be widely used in the printing industry, from the text printing to the traditional printing environment, its reliability, simplicity, and low operating costs, will be the printing plant to use this technology advantages. A wide range of applications, such as: very high printing speed, a wide range of printable materials, a simple mechanical structure, high durability and stability. Unlike early printing technologies, electro-magnetography promises much room for growth in the future. Today's presses can print 800 pages per minute and 1,400 pages in the future. And now is engaged in multi-color printing and new high-resolution research, I believe that in the 21st century, this type of printing will be able to become the leading position in the printing industry, in a variety of materials to complete a variety of high-speed print printing operations.