The so-called
Inkjet Printer is to form letters or images by ejecting ink droplets onto the print media. The early ink-jet printers and the current large-format ink-jet printers all use the continuous ink-jet technology, and the popular ink-jet printers in the market currently adopt the random ink-jet technology. The two ink jet technologies are very different in principle.
Inkjet printers can be broadly divided into A4 inkjet printers, A3 inkjet printers, and A2 inkjet printers if they are divided from the print format. If they are used, they can be divided into ordinary inkjet printers and digital photo printers. Mobile inkjet printer.
How inkjet printers work
1 , continuous inkjet technology
Continuous ink jet technology is represented by a charge modulation type. This principle of ink-jet printing is the use of a
Piezoelectric actuator to apply a constant pressure to the ink in the print head so that it is ejected continuously. For recording, the vibration signal of the oscillator is used to stimulate the jet to generate ink droplets, and the size and spacing of the ink droplets are controlled. The print information from the character generator and the analog modulator controls the charge on the control telegram to form charged and uncharged ink droplets. The deflecting electrode then changes the flying direction of the ink droplets so that ink droplets that need to be printed can be printed. Fly to paper to generate character/graphic records. The ink droplets that did not participate in the record were recovered by the catheter. For the deflection electrode, some systems use two pairs of mutually perpendicular deflection electrodes to perform two-dimensional deflection of the ink droplet printing position; some systems adopt multidimensional control of the deflection electrode, namely a multi-dimensional deflection type.
This continuous cycle of inkjet system. High-speed ink droplets can be generated, so the printing speed is high and plain paper can be used. Different print media can obtain high-quality print results, and it is also easy to implement color printing. However, the structure of this ink jet printer is more complex than the random one: the ink needs a pressurizing device, and the terminal must have a recovery device to recover and not participate in the record. And the efficiency of working methods is not high enough and it is not accurate. Inkjet printers using this technology are rarely seen today.
2. Random inkjet technology
In the random ink jet system, ink is ejected only when it is needed for printing, so it is also called on-demand type. Compared with the continuous type, the structure is simple, the cost is low, and the reliability is high. However, due to the inertia of the jet, the ink droplet ejection speed is low. In this random ink jet system, in order to compensate for this shortcoming, many random ink jet printers adopt a multi-nozzle method to increase the printing speed.
At present, random-type inkjet technology mainly includes two types: micro piezoelectric type and hot bubble type:
a . Hot bubble jet technology
Inkjet printers generally use thermal bubble jet technology, which uses ink to heat, swell, and compress ink in a short period of time to eject ink onto printing paper to form ink dots, increasing the color stability of ink droplets, and achieving high speed and high quality. print. Because of the size of the ink droplets, the uniformity of the shape and density of the ink droplets will have a significant effect on the image quality. The ink dot direction and shape produced at high temperatures are not easy to control, so the high-precision ink droplet control is very important. The principle of thermal bubble jet printing is to load the ink into a very tiny capillary tube and quickly heat the ink to the boiling point through a miniature heating pad. This creates a very tiny vapor bubble that expands to eject a drop of ink to the top of the capillary. Heating is stopped, and the ink cools, causing the steam to condense and shrink, thereby stopping the flow of ink until the next time steam is again generated and an ink droplet is generated.
b . Micro Piezo Technology
The micro-piezoelectric technology divides the control of the ink droplets during the ink-jet process into three phases: Before the ink-jet operation, the piezoelectric element first shrinks slightly under the control of the signal; then, the element produces a large extension, and drops the ink. The nozzle is ejected; at the moment when the ink droplets are to leave the nozzle, the components will shrink again, and the ink level will be contracted from the nozzle cleanly.
In this way, the liquid level 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-piezo inkjet system has a transducer disposed on an ink-filled head, and the transducer is controlled by a print signal to control ink ejection. According to the working principle and arrangement structure of the micro-piezoelectric inkjet transducer, it can be divided into several types: piezoelectric tube type, piezoelectric film type, and piezoelectric film type.
The use of changes in the micro voltage to control the ejection of the ink dots not only avoids the disadvantages of the thermal bubble jet technology but also can precisely control the ink jet direction and shape. Piezoelectric inkjet printheads use a piezoelectric crystal at the rear of the microink reservoir. Applying a current to the crystal will cause it to spring 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 backward again and enters the ready state for the next drop of ink.
Compared with these two methods, thermal bubble print heads are subject to chemical changes and unstable properties at high temperatures, so the authenticity of the colors produced will be affected to a certain extent; on the other hand, ink is ejected through bubbles. The directionality and volume size of the ink particles are not well understood, and the edges of the printed lines are jagged and uneven, which affects the print quality to a certain extent, which is an inadequacy thereof. The micro-piezoelectric print head technology utilizes the discharge characteristics of the crystal during pressurization and ejects the ink stably at a normal temperature. The ability to control the ink droplets is strong, and the color point is also reduced to a large extent, and the ink dots produced do not have a tail, so that the printed image becomes clearer. Easy to achieve high-precision print quality up to 1440dip, and no need to heat the micro-piezo inkjet, the ink will not change due to chemical changes in the heat, it greatly reduced the requirements of the ink. In addition, the piezoelectric print head is fixed in the printer, so only need to replace the
Ink Cartridge. Hot bubble inkjet printers require ink jets to be installed in each cartridge: this increases the cost of the cartridge. However, the disadvantage of the piezoelectric ink jet printer is that if the piezoelectric print head is damaged or blocked, the entire printer needs to be repaired.
