1.Electronic ink-liquid ink of HP Indigo
HP IndigoDigital printing machineAll use electronic ink, which is a specially developed liquid ink composed of charged ink particles. Similar to the electrostatic toner in the electrostatic printing method, the electronic ink can be transferred to the printing position under the electrostatic force, thereby realizing digital printing. However, unlike electrostatic toners, the size of dots printed with electronic ink is very small, reaching 1 to 2 nm. This small size can achieve higher image resolution, the printed product is more shiny, the edges of the image are clearer, and it has a more subtle image gradation, which means that the quality of printing with electronic ink can reach the level of traditional offset printing. When using electrostatic toner digital printing, the ink particles should not be too small, otherwise the ink particles will become an air cushion and cannot be controlled. Therefore, as the printing speed becomes faster and faster, the size of the ink particles must also become larger and larger. Since electronic inks are liquid charged particles, it is possible to control smaller particle sizes to suit the requirements of color printing quality. In short, HP Indigo's electronic ink can achieve the high quality, clear edges, and glossy printing quality of traditional lithographic offset printing.

2.BID development technology

  As shown in Figure 2-15, the BID (Binary Ink Development) development of the HP Indigo digital printing machine does not eject ink on the photoconductor drum, but injects ink on the photoconductor drum through the development roller. It does not perform at the same development position for all colors, but each color has a different position. BID technology can increase the speed of development, thereby increasing the speed of printed products. In the first generation of products, all color separations share a set of development system, which consists of cylinders and rollers with different functions and other mechanical structures, and completes the image formation process of all color separations according to the timing of the printing process. In the second-generation technology, each color separation has an independent BID development system. During the printing process, the development systems of different color separations contact/leave with the photoconductor drum in sequence, supply the corresponding color ink to the photoconductor drum, and recycle Excess ink, complete the development process of their respective color separation. The advantages of the BID development system are obvious. The independent systems greatly reduce the incidence of failures and completely avoid the occurrence of abnormal situations such as ink mixing. At the same time, because only the actions of different BID developing systems need to be controlled during color switching, the printing speed can also be increased.