The printhead is one of the key components of an inkjet printer. It is mainly responsible for ejecting ink at high speed when the inkjet printer is working so that it can form an image on the printing medium. Common printheads of inkjet printers mainly include thermal (heat-sensitive) printheads and piezoelectric printheads.
Piezoelectric printheads refer to printheads made of special crystal materials that can sensitively respond to voltage. The key component of the piezoelectric inkjet printhead is the piezoelectric element. The current signal controls the deformation of the piezoelectric element, thereby ejecting the accumulated ink, which can more accurately control the size and ejection direction of the ink droplets, ensuring precise control of the ink. Micro-piezoelectric printheads are different from thermal foam printheads. Since the entire ink ejection process is completed at room temperature and does not require heating, in principle piezoelectric printheads are more durable than thermal foam printheads. In fact, the same is true above.
Piezoelectric Printhead Structure
The key part of piezoelectric inkjet technology is the piezoelectric printhead. The piezoelectric printhead consists of piezoelectric material nozzles and ink storage chambers. The nozzle hole is a channel that connects the ink storage chamber and the printing medium. The ink storage chamber stores ink. Piezoelectric materials are responsible for producing the piezoelectric effect. The piezoelectric effect refers to the phenomenon that certain crystals will produce charge separation under the action of external force. Specifically, when force or pressure is applied, the positive and negative charges inside the crystal will separate, resulting in a charge difference and a potential difference. This phenomenon is called the positive piezoelectric effect. When opposing force or pressure is applied, the potential difference is reversed, which is known as the negative piezoelectric effect.
Piezoelectric Inkjet Printing Technology
Piezoelectric inkjet printing technology is a technology commonly used in inkjet printers. The main manufacturer is Epson. It uses the piezoelectric effect to eject ink to achieve printing functions. This article will introduce the working principle of piezoelectric inkjet technology from a principle perspective. In the following parts, JOHOPE Technology will introduce this printing technology.
How does Piezoelectric Inkjet Printing Technology Work?
1. Ink supply
Before starting work, ink is first supplied to the ink storage chamber of the inkjet head. The ink storage chamber has an ink channel connected to the ink supply system, and the ink is sent into the ink storage chamber through a pressure difference. The ink in the ink storage chamber is kept under constant pressure to ensure the stability of the inkjet.
2. Signal transmission
After the printing task starts, the computer will transmit the printing data to the inkjet printer control system. The control system generates corresponding control signals based on the printing data and transmits them to the piezoelectric inkjet head through a cable.
3. Piezoelectric effect
When the control signal is transmitted to the piezoelectric inkjet head, the piezoelectric material is acted upon by voltage, producing a piezoelectric effect. The action of voltage causes the piezoelectric material to deform, causing the piezoelectric material to shrink or stretch, thereby changing the size of the nozzle hole.
Inkjet printer with piezoelectric printhead
4. Ink jet
The deformation of the piezoelectric material causes changes in the size of the nozzle holes. When the nozzle holes shrink, the ink will be pushed out of the nozzle holes, forming ink droplets. After the ink droplets pass through the nozzle holes, they are dispersed into small ink droplets by the electric field and are fired toward the printing medium at high speed.
5. Control Accuracy
In order to ensure the accuracy and clarity of printing, the control system needs to accurately control the deformation of the piezoelectric material. By changing the voltage and frequency of the control signal, the deformation degree of the piezoelectric material can be adjusted, thereby achieving the control accuracy of the inkjet.
Advantages of Piezoelectric Inkjet Printing Technology
Piezoelectric inkjet printing technology has a stronger ability to control ink droplets, and the shape of the ink droplets is more regular, the positioning is more accurate, the printing resolution is higher, and high-precision printing is easily achieved. In addition, piezoelectric inkjet printing technology does not require heating of ink, and the ink will not undergo chemical changes due to heat, which expands the range of ink choices and extends the life of the inkjet print head. Because the temperature during inkjet printing is in a constant and stable state, the viscosity and surface tension of the ink remain relatively stable after a long period of uninterrupted printing, thus ensuring the consistency of print quality and the color of customer reprints. Represent unity.
Ceramic piezoelectric inkjet printing systems can print almost any kind of ink, including water-based and solvent-based. The ink used for piezoelectric inkjet printing has a wide range of viscosity and surface tension options and has solubility and quick-drying properties. The viscosity can be between 1-20 mPa.s, and the tension can be between 30~50mN/m. Therefore, piezoelectric inkjet printing technology makes up for the shortcomings of thermal foaming inkjet printing technology and has a wider application space.
In addition, the nozzle and ink cartridge in the piezoelectric inkjet print head are independent structures. One nozzle can support multiple ink cartridges. When replacing ink, you only need to replace the ink cartridge instead of the print head, which can save part of the cost of printing consumables.
Disadvantages of Piezoelectric Inkjet Printing Technology
The biggest disadvantage of piezoelectric inkjet printing technology is that it is difficult to concentrate a larger number of nozzles on one print head, so the printing speed will be slower. The cost of inkjet printheads made with piezoelectric technology will also be relatively high, and once damaged, it will be relatively expensive to repair.
Another disadvantage is that piezoelectric inkjet printing technology wastes a lot of ink when printing. When the printer nozzle is clogged, a large amount of ink needs to be wasted to clean the nozzle. Every time the nozzle is replaced, 30% of the ink must be wasted first for ink head cleaning. , it takes 2 to 3 minutes to clean every time it is turned on, and some ink is wasted. When the air volume sensing device requires the user to replace the ink cartridge, there is still about 20% of ink remaining in the ink cartridge.
In addition, JOHOPE Technology analyzes another printing technology-thermal foaming inkjet printing technology. Click the link to have a deep insight into this technology.