Inkjet or laser printer. Thermal inkjet and piezoelectric printing - pros and cons

Today, there are two main printing technologies on the printing device market: piezoelectric and thermal inkjet.

Piezoelectric printing technology is developed on the ability of piezocrystals to deform under the influence of electricity. Due to the use of this technology, it has become possible to control printing, namely: monitor the size of the drop, the speed of its exit from the nozzles, as well as the thickness of the jet, etc. One of the advantages of such a system is that the droplet size can be controlled. This ability allows you to obtain higher quality images.

To date, experts have proven that the reliability of such systems is much higher than other systems. inkjet printing.

When using this technology, the print quality is very high. Even universal and inexpensive models allow you to obtain images of the highest quality and high resolution. Also, the most important advantage of PU with a piezo system is its high color rendering, which allows the image to look bright and rich.

Epson technologies - time-tested quality

Printheads inkjet printers EPSON is a high-quality development, and this is precisely what explains their high price. If you use a piezoelectric printing system, then you are guaranteed reliable operation printing device, and the print head does not dry out or become clogged, due to the fact that it has minimal contact with air. The piezoelectric printing system was developed and implemented by EPSON; only EPSON has a patent for the use of this system.

The thermal inkjet printing principle is used in Canon, HP, and Brother printing devices. By heating the ink, it is applied to the paper. By means of an electric current, liquid ink is proportionally heated, which explains the name this method printing - thermal inkjet. The increase in temperature is produced by a heating element located inside the thermal structure. With a strong increase in temperature, the main part of the paint evaporates, the pressure in the structure quickly increases, and a small drop of paint comes out of the heat chamber through a precision nozzle. This process is repeated repeatedly after one second has elapsed.

The main disadvantage of the thermal inkjet method is that with such a printing technology, enough a large number of precipitation, which over time can cause it to fail. Also, this scale clogs the nozzles over time, which leads to a loss of quality and print speed of the printer.

Also, devices that use thermal inkjet printing, due to constant temperature fluctuations, deteriorate the print heads, as it simply burns out under the influence of extreme temperatures. This is the main disadvantage of such devices. The service life of the Epson PG MFP is absolutely identical to the service life of the device itself. This became possible thanks to the high-quality materials from which the print head is designed. Customers who use thermal inkjet printing will often have to change the print head, because due to high temperature it will often burn out, which will significantly increase financial costs. The quality of the print head will also make a huge difference if users are using refillable cartridges.

Using an Epson inkjet printer in conjunction with refillable cartridges is very beneficial, as the quality of the printer’s operation increases and the cost of each printed image decreases.

The print head of EPSON printers is of great importance not only for stable operation printer. The quality of PG allows you to increase the quality of printing and its speed. Also, if the print head does not come into contact with air and dry out, the user will not have to change it, and therefore waste money in vain. Devices that use the thermal inkjet operating principle can overheat greatly, and accordingly the print head can also overheat, which can simply burn out if overheated too much and get out of standing.

As numerous checks and tests show, in order for printing to be as economical as possible and at the same time to be bright and effective, engineers recommend using EPSON printing devices with CISS. EPSON devices work with the CNC system much longer and more efficiently than other PUs of the same price from other manufacturing companies.

Epson is a reliable manufacturer of quality products that will make your work easier and more productive.

In contact with

Classmates

Technology thermal inkjet printing based on the property of ink to expand in volume when heated. The heated ink, increasing in volume, pushes microscopic ink drops into the nozzles of the printer's print head, which form an image on the paper. IN general view Thermal inkjet printing technology is presented below.

Thermal inkjet technology

Thermal inkjet printing is the most popular inkjet technology and is used in 75% of inkjet printers.

Share of printers using thermal inkjet printing technology

Corporations made the greatest contribution to the development of thermal inkjet printing technology Canon And HP, who in the 70s of the twentieth century independently developed two printing technologies: Bubble Jet (Canon) and Thermal Inkjet(HP).

Thermal inkjet printing technologies

Bubble Jet thermal inkjet printing technology was introduced to the public in 1981 at the Grand Fair. In 1985 using innovative technology The legendary monochrome printer Canon BJ-80 was released, and in 1985 the first color printer Canon BJC-440 was released.

Schematic illustration of Bubble Jet inkjet technology

The essence of technology inkjet printing Bubble Jet is as follows. A thermistor (heater) is built into each print head nozzle to instantly heat up the ink, which, at temperatures above 500°C, evaporates and forms a bubble that pushes a drop of ink out. Then the thermistor turns off, the ink cools and the bubble disappears, and the zone low blood pressure draws in a new portion of ink.

Interestingly, the ink heats up to a temperature of 500°C in just 3 microseconds, and droplets fly out of the nozzle at a speed of 60 km/h. Every second, the ink heating and cooling cycle is repeated 18 thousand times in each print head nozzle.

The second inkjet printing technology, Thermal Inkjet, began to be developed by HP in 1984, but the first ThinkJet printer based on this printing technology was introduced into mass production much later.

Schematic illustration of Thermal Inkjet technology

Thermal Inkjet technology Based on the same printing principle as Bubble Jet technology, the only difference is that in printers using Bubble Jet technology, thermistors are located in the microscopic nozzles of the print head, and in printers using Thermal Inkjet technology, they are located directly behind the nozzle.

Thus, the Bubble Jet and Thermal Inkjet technologies differ only in details.

The main advantages of thermal inkjet printing over piezo inkjet printing are the absence of moving mechanisms and stability of operation. Along with this, thermal inkjet printing has one significant drawback: it does not allow you to control the size and shape of ink droplets. In addition, when ink drops fly out of the print head nozzle, satellite drops, formed when the ink boils, burst out along with them. The appearance of such “satellites” can be triggered by unstable vibration of the ink mass during its ejection from the nozzle. It is the satellite drops that cause the formation of an unwanted outline (“ink fog”) around the print and color mixing in graphic files.

The core of any inkjet printing process is the process of creating droplets of ink and transferring those droplets onto paper or any other inkjet-compatible media. Controlling the flow of droplets allows you to achieve different density and tonality of the image.
Today, there are two different approaches to creating a controlled droplet flow. The first method, based on creating a continuous flow of droplets, is called the method continuous inkjet printing. The second method of creating a flow of drops provides the ability to directly control the process of creating a drop at the right time. Systems using this method of controlling droplet flow are called systems pulse inkjet printing.

Continuous Inkjet Printing

The pressurized dye enters the nozzle and is separated into droplets by generating rapid pressure fluctuations produced by some electromechanical means. Pressure fluctuations cause a corresponding modulation of the diameter and speed of the dye jet emerging from the nozzle, which is divided into individual droplets under the influence of surface tension forces.
This method allows you to achieve a very high speed of creating droplets: up to 150 thousand pieces per second for commercial systems and up to a million pieces for special systems. An electrostatic deflection system is used to control droplet flow. Droplets flying out of the nozzle pass through a charged electrode, the voltage on which changes in accordance with the control signal. The flow of droplets then enters the space between two deflecting electrodes that have a constant potential difference. Depending on the charge received previously, individual drops change their trajectory in different ways. This effect allows you to control the position of the printed dot, as well as its presence or absence on the paper. In the latter case, the drop is deflected so much that it ends up in a special catcher.
Such systems make it possible to print dots with a diameter from 20 microns to one millimeter. A typical dot size is 100 microns, which corresponds to a droplet volume of 500 picoliters. Such systems are mainly used in the industrial printing market, in product labeling systems, mass label printing, medicine, etc.

Pulse inkjet printing

This principle of creating a stream of drops allows for the possibility of directly controlling the process of creating a drop at a certain time. Unlike continuous systems, there is no constant pressure in the ink volume, and when it is necessary to create a drop, pressure pulses are generated. Controlled systems are fundamentally less complex to manufacture, but their operation requires a device for generating pressure pulses approximately three times more powerful than for continuous systems. The productivity of controlled systems is up to 20 thousand drops per second for one nozzle, and the diameter of the drops is from 20 to 100 microns, which corresponds to a volume from 5 to 500 picoliters. Depending on the method of creating a pressure pulse in the ink volume, a distinction is made between piezoelectric and thermal inkjet printing.
For implementation piezoelectric method, a piezoelectric element is installed in each nozzle, connected to the ink channel by a diaphragm. Under the influence of an electric field, the piezoelectric element is deformed, due to which the diaphragm contracts and expands, squeezing a drop of ink through the nozzle. A similar drop generation method is used in Epson inkjet printers.
Positive attribute such inkjet printing technologies is that the piezoelectric effect is well controllable electric field, which makes it possible to quite accurately vary the volume of the resulting droplets, and therefore sufficiently influences the size of the resulting spots on the paper. Nevertheless, practical use Modulation of the volume of drops is complicated by the fact that not only the volume but also the speed of movement of the drop changes, which, when the head moves, causes errors in the positioning of the point.
On the other hand, the production of print heads for piezoelectric technology turns out to be too expensive per head, so in Epson printers the print head is part of the printer and the cost can be up to 70% of the total cost of the entire printer. Failure of such a head requires serious service.

For implementation thermojet method, each of the nozzles is equipped with one or more heating elements, which, when current is passed through them, are heated to a temperature of about 600C in a few microseconds. A gas bubble that appears during sudden heating pushes a portion of ink through the nozzle outlet, forming a drop. When the current stops, the heating element cools down, the bubble collapses, and another portion of ink from the input channel takes its place.
The process of creating droplets in thermal print heads after applying a pulse to a resistor is almost uncontrollable and has a threshold dependence of the volume of the evaporated substance on the applied power, so here dynamic control of the droplet volume, unlike piezoelectric technology, is very difficult.
However, thermal printheads have the highest performance-to-cost per unit production ratio, so the thermal inkjet printhead is usually part of the cartridge and when replacing the cartridge with a new one, the printhead is automatically replaced. However, the use of thermal print heads requires the development of special inks that can evaporate fairly easily without ignition and are not subject to destruction due to thermal shock.

Lexmark printhead

The print head of a black cartridge with a regular resolution of 600 dpi for early models (Lexmark CJP 1020, 1000, 1100, 2030, 3000, 2050) had 56 nozzles arranged in two zigzag rows. The print head for color cartridges of these models had 48 nozzles divided into three groups of 16 nozzles for each color (Cyan, Magenta, Yellow). The Lexmark CJ 2070 printer used a different print head, which contained 104 monochrome nozzles and 96 color nozzles.
For the production of print heads for Lexmark inkjet printers, starting from the 7000 series, print heads are used that are manufactured using laser nozzle flashing technology (Excimer, Excimer 2). The first printhead models contained 208 monochrome nozzles and 192 color nozzles.
For Z51 and older model The Zx2 and Zx3 families have developed their own print head with 400 nozzles. In the Z51 model, only half of the nozzles were used, and the rest worked in hot standby mode, when, like in the following models, all the nozzles were simultaneously used.
The junior and mid-range models of the Zx2 family use cartridges that are modifications of standard high-resolution cartridges, while the junior and mid-range models of the Zx3 family use new models of Bonsai cartridges.
Do not leave the print head nozzles open for long periods of time. If the nozzles are left open, the ink in them dries out and clogs the channels, which leads to printing defects. The cartridge should be left in the printer or in a special box (« garage»). It is also undesirable to touch the nozzles and contacts with your hands, as sebaceous secretions from the skin can spoil the surface.

Printhead Specifications

Period of meniscus formation:
This is the period of time required to refill the chamber with ink. It defines operating frequency print head (from 0 to 1200 Hz).

Drop speed:
Low speed results in a continuous point location.
High speed leads to splashes and streaks.

The mass of the drop is determined by:
The size of the heating element.
Nozzle diameter.
Back pressure.

It has been noticed that in conventional inkjet printers, a drop of ink hitting the paper takes the shape of a small triangle, so the lines look jagged upon closer inspection. This is due to the fact that the drop is deformed in flight, and when it comes into contact with paper, it blurs. This is especially noticeable in low mode during economical printing. Lexmark offers printers with a new, advanced printing technology in which the shape of the nozzles and the speed of the head are balanced so that a drop of ink produces spots like even strokes. This results in smooth lines and print quality almost indistinguishable from laser printing. In addition, this shape of the spot allows you to avoid whitish streaks on the print.

What is ink?

Each inkjet printer manufacturer develops and improves its own ink composition, which is most adapted to the equipment being produced. Lexmark's main inkjet ink components are:
-Deionized water (85-95% of total volume)
-Pigment or dye
- Solvent (for pigments)
-Humectant
-Surfactant
-Biocide
-Buffer (pH stabilization)

Pigment or dye. Pigment-based inks (black only) are made from solid particles suspended in a liquid. When such ink gets on paper, the liquid evaporates and is partially absorbed, and the powder adheres to the surface without spreading over it. Therefore, pigment-based inks are water-resistant, have weak penetration into paper fibers, but are sensitive to light.
Dye-based inks are typically colored inks. The dye is soluble in water and is absorbed along with it into the thickness of the paper when it dries. Such inks dry faster than pigment inks, are lightfast, but produce average stains irregular shape more than the last ones.
Humidifier. The concentration of the humidifier affects the viscosity of the ink. This parameter should be optimal for the given ink composition and the print head with which it will be used. Indeed, on the one hand, the higher the viscosity, the worse the ink spreads over the surface of the paper, giving a smaller dot size and the clearer the image will be. On the other hand, too high a viscosity results in a prolonged meniscus formation time, which degrades printing speed. Typically, ink viscosity is a key parameter in determining the geometric channels in the print head.
Surface tension affects the wettability of ink on all surfaces with which it comes into contact, from the reservoirs in the cartridge to the surface of the paper. If the statistical surface tension is too low, the ink dries faster on the paper surface, but the average drop volume when squeezing ink out of the nozzles is too high. Too high surface tension increases drying time and therefore reduces the durability of the image when printed.
Acidity level(PH) low acidity leads to low solubility of ink components in water and, as a result, poor water resistance of the image. The standard acidity level is in the range from 7.0 to 9.0.
Inside the cartridge there are ink reservoirs, print head nozzles and electrical contacts.
The color cartridge contains 3 separate ink cells for three different colors. A monochrome cartridge contains only one cell of black ink.

Ink and colors

Correctly transferring the color of an image onto paper is a highly technological process that requires taking into account a considerable number of factors, including subjective assessment. First of all, the color reproduction of the image depends on chemical composition ink and paper, printer architecture.
A mandatory requirement for ink is a very fine spectral composition, otherwise the colors obtained when mixed will be “dirty”. Once dry, the ink must remain transparent, otherwise there will be no natural color mixing.
An important factor is also resistance to fading, environmental friendliness and non-toxicity.
It is believed that the optimal composition of ink is already known. Almost all manufacturers use them as a suspension of very small particles of mineral pigment. With colored inks the situation is worse, since it is very difficult to select mineral dyes of the desired spectral composition.
Currently, color rendering procedures are based on the so-called color tables ah, which are used to convert the color space in which the original image was created into some “deformed” color space that takes into account the peculiarities of the transmission of colors on paper with ink. Typically, separate color tables are built for each paper type and optimized for each individual ink type and printhead.

Lexmark Drivers

Lexmark printer drivers are ready to print once installed, with automatic object recognition mode allowing you to good quality images without pre-setting. Automatic mode also allows you to achieve the optimal combination of document print quality and speed. Driver settings for special paper or selecting color tables for a more contrasting or natural tone of the image is very simple in the “Document Quality” section of the driver settings.
Lexmark Color Fine 2 Series drivers allow you to automatically detect the type of cartridge, thereby significantly simplifying the procedure for configuring all systems to a different type of cartridge or replacing an old one with a new one. Characteristic feature drivers of this series is their ability to work with images in the sRGB and ICM standards.
sRGB standard proposes that a device-independent color space built into the Microsoft OS or Internet tools is used to describe a color image. Using the standardized RGB description of the UTI-R BT.709 color space, this standard allows us to minimize the transmission along with the image of additional information associated with the color profile of the equipment on which the image was created. The system part of the image file only provides a reference to the standard in which it was created, and the destination position is actively used by the color space description provided by the operating system.
ICM standard allows you to more accurately define the diversity of color image generation and display devices by using color hardware profiles for each type of image generation and display device. However, this approach implies that system information, associated with the profile of the equipment on which the image was created, is displayed in place with this image.

Photo printing

A serious problem in inkjet printing is the correct reproduction of the light tones of the image. The fact is that conventional color solutions for inkjet printing produce saturated color dots, so to obtain pale shades you need to apply drops of ink quite rarely. This causes the spots to be so far apart when transmitting very light tones that the grain in the image becomes noticeable, and also causes problems with the rendering of highlights.
One of radical ways The solution to this problem is to use additional light-colored inks. In this case, dark tones are obtained by filling with lightened ink. A cartridge with such ink usually replaces the second cartridge (black) and contains lightened Cyan, lightened Magenta and black inks. A light yellow tone is not used because this color is perceived by the human eye without much difference as yellow.

This is the most common type of printer. It became so thanks to its low price and high quality printing. Printing color photographs, images or plain text is not a problem with these printers.

But, despite the obvious advantages of such printing machines, they also have disadvantages.

We will talk about this in our material.

Working principle of an inkjet printer

An inkjet image is created from small dots that are created by shooting microscopic streams of ink from the head. The operating principle is similar to a dot matrix printer, only without needles.

Types of Inkjet Printers

Inkjet printers are divided according to the method of “spitting out” ink:

• Piezoelectric
• Thermal

In the first case, the jet is created using the pressure created by a piezoelectric element, in the second, the pressure is created by local heating. The advantages and disadvantages of the two types are identical.

Advantages and disadvantages of inkjet printers

Let's start with negative aspects inkjet printers:

• Low print speed compared to laser printers. This will not be critical at all if you are printing an essay or report, but if you want to print “War and Peace” by Leo Tolstoy, you will have to wait.
• If you do not use your inkjet printer for a long time, the ink may dry out. You will have to change the cartridge.
• High cost of original Supplies. Of course, there are exceptions for some printers, the price of original cartridges for which is low, but this is more likely the exception than the rule. This disadvantage can be eliminated - see advantages. By the way, in order to print War and Peace, you will most likely have to run to the store several times for a new cartridge.

Now about the advantages of inkjet printers:

• As noted above, an inkjet printer costs much less than its counterparts.
• It is possible to print color photographs. Look carefully when purchasing technical specifications, there are also monochrome inkjet printers (i.e., black and white printing only).
• Small dimensions compared to other printers.
• It is possible to refill cartridges yourself. This process is often not provided by the manufacturer, so there is a risk of damaging the printer and possibly voiding the warranty.
• For some models it is possible to install

Which printing technology is better? Thermal jet or piezoelectric jet? And with what?

1. There are two main printing technologies common in the inkjet printing market: piezoelectric and thermal inkjet.

   The differences between these systems are in the method of depositing a drop of ink onto the paper.

   Piezoelectric technology was based on the ability of piezocrystals to deform when exposed to electric current. Thanks to the use of this technology, full control of printing is achieved: the size of the drop, the thickness of the jet, the speed of ejection of the drop onto the paper, etc. are determined. One of the many advantages of this system is the ability to control the size of the drop, which allows you to obtain high-resolution prints.

   The reliability of the piezoelectric system has been proven to be significantly higher compared to other inkjet printing systems.

   The print quality when using piezoelectric technology is extremely high: even universal inexpensive models allow you to get prints with almost photographic quality and high resolution. Another advantage of printing devices with a piezoelectric system is the naturalness of color rendering, which becomes really important when printing photographs.

   The printheads of EPSON inkjet printers have high level quality, which explains their high cost. The piezoelectric printing system ensures reliable operation of the printing device, and the print head rarely fails and is installed on the printer, and is not part of replaceable cartridges.

   The piezoelectric printing system was developed by EPSON, it is patented and its use is prohibited by other manufacturers. Therefore, the only printers that use this system printing is EPSON.

   Thermal inkjet printing technology is used in Canon, HP, Brother printers. Ink is supplied to paper by heating it. The heating temperature can be up to 600C. The quality of thermal inkjet printing is an order of magnitude lower than piezoelectric printing, due to the inability to control the printing process due to the explosive nature of the drop. As a result of such printing, satellites (satellite drops) often appear, which interfere with obtaining high quality and clarity of prints, leading to distortion. This drawback cannot be avoided, since it is inherent in the technology itself.

   Another disadvantage of the thermal inkjet method is the formation of scale in the print head of the printer, since ink is nothing more than a combination of chemical substances, dissolved in water. The resulting scale clogs the nozzles over time and significantly deteriorates the print quality: the printer begins to streak, color rendition deteriorates, etc.

   Due to constant temperature changes in devices using thermal inkjet printing technology, the print head is gradually destroyed (burns out under the influence of high temperature when the thermoelements overheat). This is the main disadvantage of such devices.
   The service life of the print head of EPSON printers is the same as the device itself, thanks to the high quality of manufacturing of the PG. Users of devices with thermal inkjet printing will have to buy a new print head each time and replace it, which not only reduces the durability of the printer, but also significantly increases printing costs.
   The quality of the print head also matters when using non-original consumables, in particular CISS.

   Using Epson CISS allows the user to increase print volumes by 50%.
   The print head of EPSON printers, as has been mentioned more than once in this article, is of high quality, due to which an increase in print volumes does not negatively affect the operation of the printer, but on the contrary allows the user to get maximum savings without compromising print quality.

2. Read about these technologies on the internet and compare which is best for you. For example, this table: http://www.profiline-company.ru/about/info/struy/piezo/
   Epsons have a separate print head, only the ink cartridges are replaced. It’s cheaper, and you can install a CISS (the printing will be very cheap), but if the paint in the head dries out, it’s easier to buy a new printer. The thermal print head contains ink and heads in one bottle. If it dries out, just buy a new cartridge (although expensive models also have separate heads and cartridges).
   Previously, I liked piezoelectric technology more: the paint was “imprinted” more strongly into the paper, which is why it smeared less. Now I do not know.
3. Piezo printing is better. Brother also uses it. Its only advantage is that if there is no paint in the nozzles, the nozzles will not burn out. This can actually happen if you don’t monitor the printing - for example, the HP’s head slows down greatly - and print with the residual ink check disabled - it is simply necessary to disable it on non-originals and CISS.

   That is, if you do not watch the printer when printing, then it is better to take a piezo.
   On the other hand, this can only happen if it is installed incorrectly, after changing cartridges during the first prints, or if you stop checking the ink level yourself.
   And the cost of the head is tolerable (and it is also a consumable), within two thousand. This is not comparable to laser spare parts at all.