The so-called Inkjet Printer is to form characters or images by ejecting ink droplets onto the printing medium. Early inkjet printers and current large-format inkjet printers all use continuous inkjet technology, while the current popular inkjet printers generally use random inkjet technology. These two inkjet technologies ... The so-called inkjet printer is to form text or images by ejecting ink droplets onto the printing medium. Early inkjet printers and current large-format inkjet printers all use continuous inkjet technology, while the current popular inkjet printers generally use random inkjet technology. The two inkjet technologies are very different in principle.
Inkjet printers can be roughly divided into A4 inkjet printers, A3 inkjet printers, and A2 inkjet printers if they are divided from the printing format alone; if they are divided from the purpose, they can be divided into ordinary inkjet printers and digital photo printers, portable Mobile inkjet printer.
How inkjet printers work
1. Continuous inkjet technology
Continuous inkjet technology is represented by the charge modulation type. The principle of this inkjet printing is to use a Piezoelectric driving device to apply a fixed pressure to the ink in the nozzle to make it continuously eject. For recording, the vibration signal of the oscillator is used to excite the jet to generate ink droplets, and the size and spacing of the ink droplets are controlled. The printing information from the character generator and analog modulator controls the charge on the control telegram to form charged and uncharged ink droplets, and the deflection electrode changes the flying direction of the ink droplets, so that the ink droplets to be printed Fly to the paper and generate character / graphic records. Ink drops not involved in the recording are recovered by the catheter. For the deflection electrode, some systems use two pairs of deflection electrodes perpendicular to each other to perform a two-dimensional deflection of the ink droplet printing position; some systems use a multi-dimensional control of the deflection electrode, namely a multi-dimensional deflection type.
This continuous circulation inkjet system can generate high-speed ink drops, so the printing speed is high, and plain paper can be used. Different printing media can obtain high-quality printing results, and it is easy to realize color printing. However, the structure of this inkjet printer is more complicated than that of the random type: a pressurizing device is required for the ink, and a recycling device is required for recycling at the terminal and does not participate in the recording. And the efficiency of the working method is not high enough, and it is not precise. Now inkjet printers using this technology have been rarely seen.
2. Random inkjet technology
In the random inkjet system, ink is only ejected when printing is needed, so it is also called on-demand. Compared with the continuous type, it has a simple structure, low cost, and high reliability. However, due to the influence of the jet inertia, the ink droplet ejection speed is low. In this random inkjet system, in order to make up for this shortcoming, many random inkjet printers use a multi-nozzle method to increase the printing speed.
At present, the random inkjet technology mainly includes two types of micro piezoelectric and thermal bubble:
a. Thermal bubble inkjet technology
Inkjet printers generally use thermal bubble inkjet technology, which heats, expands, and compresses the ink in a short time to eject the ink onto the printing paper to form ink dots, increase the color stability of the ink droplets, and achieve high speed and high quality. print. In addition to the size of the ink droplets, the consistency of the shape and density of the ink droplets will have a significant impact on the image quality, and the direction and shape of the dots produced by the ink at high temperatures are not easy to control, so high-precision ink droplet control important. The principle of thermal bubble inkjet printing is to fill the ink into a very tiny capillary tube and quickly heat the ink to the boiling point through a tiny heating pad. This creates a very tiny steam bubble, which expands and ejects a drop of ink onto the top of the capillary. Stop heating and the ink cools, causing the steam to condense and contract, which stops the ink flow until the next time steam is generated and an ink droplet is generated.
b. Micro Piezo Technology
Micro-piezoelectric technology divides the control of ink droplets in the ink-jet process into three stages: before the ink-jet operation, the piezoelectric element first shrinks slightly under the control of the signal; then, the element produces a larger extension, which drops the ink Push out the nozzle; the moment the ink droplet will fly away from the nozzle, the element will shrink again, and the ink liquid surface will be shrunk cleanly from the nozzle.
In this way, the liquid surface of the ink droplets is precisely controlled, and the ink droplets ejected each time have a perfect shape and a correct flying direction.
The micro piezoelectric inkjet system is provided with a transducer on the nozzle equipped with ink, and the transducer is controlled by the printing signal, thereby controlling the ejection of ink. According to the working principle and arrangement structure of the micro piezoelectric inkjet system transducer, it can be divided into several types: piezoelectric tube type, piezoelectric film type, piezoelectric sheet type and so on.
The use of micro voltage changes to control the ejection of ink dots not only avoids the shortcomings of thermal bubble inkjet technology, but also enables the print head to use a piezoelectric crystal at the rear of the micro ink reservoir. Applying current to the crystal will cause it to squeeze inward. When the current is interrupted, the crystal bounces back to its original position, and a small amount of ink is ejected through the nozzle. When the current is restored, the crystal is pulled back and extended, ready to eject the next drop of ink.
Compared with the two methods, the thermal bubble print head is prone to chemical changes at high temperatures and unstable in nature, so the authenticity of the printed colors will be affected to a certain extent; Yes, the directionality and volume of the ink particles are not easy to grasp, and the edges of the printed lines are easy to be uneven, which affects the print quality to a certain extent, which is its shortcomings. The technology of micro-piezoelectric print head is to use the characteristics of the discharge of the crystal when it is pressurized, and the ink is stably ejected at room temperature. It has stronger ability to control ink droplets, and reduces the color dots a lot, and the resulting ink dots have no Huiwei, which makes the printed image clearer. It is easy to achieve high-precision print quality up to 1440dip, and the micro piezoelectric inkjet does not need to be heated, and the ink will not undergo chemical changes due to heat, so the requirements for ink are greatly reduced. In addition, the piezoelectric print head is fixed in the printer, so only the Ink Cartridge needs to be replaced. Thermal bubble inkjet printers require inkjet nozzles in each ink cartridge: this will increase the cost of the ink cartridge. However, the disadvantage of piezoelectric inkjet printers is that if the piezoelectric printhead is damaged or blocked, the entire printer needs to be repaired.
