Inkjet Printer Principle Classification

1. Continuous Inkjet Printer
Under the pressure of the ink supply pump, the ink flows from the ink tank through the ink pipe, adjusts the pressure and viscosity, and enters the spray gun. As the pressure continues, the ink is ejected from the nozzle. When the ink passes through the nozzle, it is broken into a series of continuous ink drops with equal spacing and the same size by the action of the piezoelectric crystal. The ejected ink flow continues to move downward and passes through the charging electrode to be charged. In the charging electrode, the ink droplets are separated from the ink line. A certain voltage is applied to the charging electrode. When the ink droplets are separated from the conductive ink line, they will instantly carry a negative charge that is proportional to the voltage applied to the charging electrode. By changing the voltage frequency of the charging electrode to make it the same as the frequency of ink droplet breakage, each ink droplet can be charged with a predetermined negative charge. Under the continuous pressure, the ink flow continues to move downward and passes through the middle of two deflection plates with positive and negative voltages respectively. The charged ink droplets will deflect when passing through the deflection plate. The degree of deflection depends on the amount of charge. The uncharged ink droplets will not deflect and will fly downward all the way, flowing into the recovery pipe, and finally return to the ink tank through the recovery pipe for recycling. The charged and deflected ink droplets fall on the object passing in front of the vertical nozzle at a certain speed and angle.
2. Drop On Demand Technology
There are three types of inkjet printers with drop-on-demand technology: piezoelectric inkjet technology, pressure valve inkjet technology, and thermal foaming inkjet technology. The working principle of each is also different.
1) Piezoelectric inkjet technology: Piezoelectric inkjet printers are also called high-resolution inkjet printers or high-resolution inkjet printers. On the integrated nozzle, 128 or more piezoelectric crystals control the multiple nozzles on the nozzle plate. After processing by the CPU, a series of electrical signals are output to each piezoelectric crystal through the driver board. The piezoelectric crystals deform, so that the ink is ejected from the nozzle and falls on the surface of the moving object to form a dot matrix, thereby forming text, numbers or graphics. Then, the piezoelectric crystal returns to its original state, and due to the surface tension of the ink, new ink enters the nozzle. Because the density of ink dots per square centimeter is very high, the application of piezoelectric technology can print high-quality text, complex logos, barcodes and other information.
2) Solenoid valve inkjet printer (large character inkjet printer): The nozzle consists of 7 or 16 groups of high-precision intelligent micro valves. When printing, the characters or graphics to be printed are processed by the computer motherboard, and a series of electrical signals are output to the intelligent micro solenoid valve through the output board. The valve opens and closes quickly, and the ink is ejected into ink dots based on the internal constant pressure. The ink dots form characters or graphics on the surface of the moving printed object.
3. Thermal Inkjet Technology (TIJ)
Abbreviated as TIJ, it uses a thin film resistor to heat less than 0.5% of the ink in the ink ejection area to form a bubble. This bubble expands at an extremely fast speed (less than 10 microseconds), forcing the ink droplets to be ejected from the nozzle. The bubble continues to grow for a few microseconds and then disappears back to the resistor. When the bubble disappears, the ink in the nozzle retracts. Then the surface tension will generate suction.