Color solid ink and its printer working principle

Most people think that ink must be liquid, but now there is a printing technology that uses solid ink, which is often referred to as "phase change ink" or "hot melt ink." Usually, these names can be freely exchanged, but the name "solid ink" can only be used in the description of this technology.

The concept of a solid ink is such that it is solid at normal temperatures, but melts and turns into a liquid in an inkjet printing device, and can pass through a piezo inkjet printer like other liquid inks (but On a thermally driven bubble jet printer this cannot be achieved). One of the advantages of solid ink over water-based inks is that the melted ink not only does not dry, but also instantly cools (solidifies) on the surface of the print. This means that solid ink does not dry out in the nozzles of ink jet printers, while water-based inks are prone to this. In addition, solid inks do not penetrate into the paper fibers like liquid inks. It can stay on the surface of the paper, creating a vivid color and a wider color gamut.

After several attempts by different companies, Tektronix finally successfully developed a color inkjet printer using solid ink in 1999. The first-generation solid-ink inkjet printers had 16 ink jet nozzles for each color (yellow, yellow, blue), and 48 ink jet nozzles for black. It can print a type A (8.5 x 11 inch) paper in two minutes. Since then, the technology has been improving, and until now it has been able to print 24 pages of the same size in one minute. The latest solid ink printers have achieved four times the resolution of the first generation (16 times the original data volume). The cost of the latest printers is only one-tenth that of the first-generation solid ink printers, and its performance and cost are expected to be further improved in the future.

The first generation of solid inkjet printers printed the ink directly on paper or a transparent substrate during operation. Its print head can quickly shuttle on the page, with the paper gradually moving forward with each imprint of the print head. In each imprinting process, it can only print a 16-pixel-wide stripe (as is the case with most desktop water-based ink printers).

The most obvious disadvantage of this approach is that if you need to add solid ink, you have to develop a completely different configuration for the printer. The weight of a print head with ink generally exceeds 1.8 kg, which is about 4 pounds. The printer must be placed on a sturdy table to prevent it from becoming dangerous during the print head replacement. As a result, a lot of printing time is wasted in decelerating, stopping and reverse accelerating the print head. Although the drop position of the drop is small, people's vision system can still distinguish it. Sometimes in order to print out the intermediate color, the two primary ink droplets are also superimposed, but their overprinting order will also affect the final color effect. For example, the red color produced by the printed red ink on the yellow ink is completely different from the red color generated on the magenta ink by printing the yellow ink, and this phenomenon causes an unpleasant change in the color tone.

In addition, the gap between the print head and the substrate must also remain stable, so as to ensure the accuracy of the ink droplet position. When printing on paper of different thickness, the gap between the print head/paper must also be adjusted at any time so that different prints can be produced. Although accurate control of printhead and paper movements is a complex matter, it can help users achieve better reliability, higher production speeds, better image quality, and lower production costs. In addition, it also simplifies paper handling and transmission paths.

The most critical improvement made by Tektronix on solid ink printers was to convert its printing method to indirect printing in 1995. The concept of indirect printing is to have the printhead print an image accurately and quickly on a rotating drum (rather than to allow it to swing), and then transfer the image to the paper through a roller. This method can make the paper's transmission path easier. People simply put it directly into the printer, just like printing with an offset press. Although this method can simplify the path of the paper, it also imposes higher requirements on the ink. First, the ink must remain solid at room temperature. Second, it must be very clean and have a low melt viscosity. Only then can it be successfully ejected from the small holes in the print head (the purpose of the print head is to extend the life of the printer). The ink must be able to cool rapidly on the surface of the drum and maintain its position during the high speed rotation of the drum. Finally, this ink must also be able to transfer completely from the roller to the paper during the offset printing process.

At the heart of this printer is an anodized aluminum drum. A porous print head, the same width as the drum, can accurately eject ink droplets onto the drum surface. Drops of ink are ejected from a piezoelectric print head made of seamless steel. In addition to the small holes in the print head, it also leaves enough space for the aperture column. Each aperture column is composed of four inkjet nozzles: yellow, blue, blue and black. Every time the drum rotates one revolution, each four-color aperture column can eject ink droplets composed of yellow, blue, green and black inks according to people's needs. They can print at the same time and produce parallel ink lines around the drum. During the next rotation of the drum, the print head will move a little forward and print the ink parallel to the previous line again. Every time the drum rotates, the print head moves a little forward until the entire image is printed on the drum. The distance that the print head moves during the entire printing process is actually very small and depends mainly on the gap between each aperture column on the print head. Depending on the quality of the selected image, the drum will typically rotate eight times to generate an image, and then rotate it again to transfer the image to the paper. At the same time, it will clean the surface of the drum to prepare for the next image. The key to producing high-quality images is to maintain ink jet consistency and to produce parallel lines of ink on the surface of the cylinder using staggered printing.

Solid ink printers print images on paper can basically be divided into three steps:

1. Use a roller maintenance tool to clean the surface of the roller, remove the ink remaining from the previous printing, and use a very thin release agent to clean the surface of the anodized aluminum print cylinder.

2. The uniformly heated (135 degrees) printhead accurately ejects tiny droplets of ink (hot melt ink) onto the rotating printing cylinder. The printing cylinder is always kept at an intermediate temperature (65 degrees). As soon as the ink comes in contact with the surface of the printing cylinder, it rapidly changes from a molten liquid to a semi-solid with a ductility.

3. The paper to be printed enters the nip formed by the pressure roller and the printing cylinder through a preheater. Under the influence of heat and pressure, the image can be transferred from the roller to the paper during one press. As soon as the paper leaves the printer, the ink will completely cure and it will be ready for use immediately.

Because the solid ink does not contain solvent, it does not need to spend time drying, in addition, the image it prints is completely resistant to water. Because the ink is liquid when it comes in contact with the paper, and it quickly fixes on the surface of the paper, rather than penetrating the paper, it can print vivid colors on a variety of papers. The printing sequence of the middle color is also often the same, so that it can bring consistent and accurate color to the printed matter. The process of printing on the cylinder and transferring the image onto the paper means that the distance from the cylinder to the print head is also constant. This distance can ensure the accuracy of the ink drop position and improve the print quality of the image.

Solid ink technology is a very good solution for office and workgroup users, but it has certain flaws. For example, it takes 12 to 15 minutes to warm up before it is officially produced. Therefore, once people turn on the printer, it is best to let it continue to produce. When no activity is available, the printer can go on standby and lower the temperature of the ink in the print head to keep it above zero. The printer entering the standby state can also quickly return to the production state under the drive of the cold start button. In addition, solid ink printers also have an "Intelligent Ready" tool that understands normal office programs and automatically raises the printer to the point where it can be produced at the beginning of the business. When the weekend arrives, the tool automatically switches to standby.

Due to the good image quality and low cost of solid ink, many photographers use it to produce Yangon. Many schools also use this kind of printing technology because it is easy to use and can print on a variety of papers. Solid ink technology is the best, and more and more people use it. It is not affected by humidity or temperature, and it has extremely high stability.

A. Front panel display. The intuitive front panel interface simplifies the installation process, helps people manage and handle printer problems, and allows people to find more advanced features.

B. Paper tray. It has a strong paper storage capacity: the multi-purpose tray (Tray No. 1) can hold 100 sheets and the main tray (Tray No. 2) can hold 525 sheets. In addition, people can increase the number of trays as needed. Typical tray sizes are between 3.5" x 5" and 8.5" x 14".

C. Printing roller. Solid ink technology simulates the production process of a large commercial offset press. The image is first printed on a high-precision cylinder and then transferred to paper. This can avoid problems such as misregistration that often occurs on laser printers while maintaining high-speed printing.

D. Inkjet print heads. Printing arrays with the same width as paper are an important part of the printer and are made primarily of seamless steel. It has 1,236 inkjet nozzles, and each nozzle can produce 24,000 droplets in one second. In other words, it can accurately eject 30 million ink droplets onto the drum and create a complete image every second.

E. Take the paper path. Simple paper path allows people to print on a variety of substrates. Its built-in double-sided printing function also enables automatic duplex printing of paper.

F. Paper preheater. Heat the paper to make it ready for transfer of the printed image.

G. Ink cartridges. People can add clean and environmentally friendly solid ink to the printer through the above openings. All ink tanks are sorted and only the correct color ink can be installed. One can add ink while the printer is in operation, rather than adding ink before printing as with other printers—this also helps ensure that the printer is operating properly.

H. Ink melter. The ink fuser is located at the end of the cartridge, allowing the ink to melt as needed. The melting of the ink is mainly controlled by the level of the ink reservoir on the print head.

I. Electronic pathways. Putting it aside means that users don't have to walk behind the printer to operate - helping them save big