Thermal inkjet color. Piezoelectric printing. Technology development by Epson

What is the best printing technology? Thermal inkjet or piezoelectric inkjet? And what?

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

   The differences between these systems are in the way the ink drop is brought to the paper.

   Piezoelectric technology was based on the ability of piezoelectric crystals to deform when subjected to electric current. Thanks to the use of this technology, complete control of the print is exercised: the size of the drop, the thickness of the jet, the speed of ejection of the drop onto the paper, etc. is determined. One of the many advantages of this system is the ability to control the size of the drop, which allows you to get high-resolution prints.

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

   The print quality of piezoelectric technology is extremely high: even the most versatile low-cost models produce near-photographic quality and high resolution prints. Also, the advantage of printing devices with a piezoelectric system is the naturalness of color reproduction, which becomes really important when printing photos.

   The printheads of EPSON inkjet printers have a high level of quality, which explains their high cost. With a piezoelectric printing system, reliable operation of the printing device is ensured, and the print head rarely fails and is installed on the printer, and is not part of the replacement 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. The supply of ink to paper is carried out by heating them. The heating temperature can be up to 600C. The quality of thermal inkjet printing is an order of magnitude lower than that of 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 disadvantage cannot be avoided, as 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 the ink is nothing more than a collection of chemicals dissolved in water. The resulting scale clogs the nozzles over time and significantly spoils the print quality: the printer starts to streak, color reproduction deteriorates, etc.

   Due to constant temperature fluctuations in devices using thermal inkjet printing technology, the print head is gradually destroyed (burns out under the action of high temperature when the fusers overheat). This is the main disadvantage of such devices.
   The service life of the print head of EPSON printers is the same as that of the device itself, due to the high quality of the PG workmanship. Users of thermal inkjet devices will have to buy a new print head and replace it every time, which not only reduces the durability of the printer, but also significantly increases the cost of printing.
   The quality of the print head also matters when using non-original Supplies, in particular CISS.

   The use of Epson CISS allows the user to increase print volumes by 50%.
   The print head of EPSON printers, as already 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 rather allows the user to get maximum savings without compromising print quality.

2. Read about these technologies on the Internet and compare what 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 change. It's cheaper, and you can put the CISS (it will be very cheap printing), but if the ink in the head dries up, it's easier to buy a new printer. In a thermal print head, ink and heads are in one bottle. If it dries up, just buy a new cartridge (although expensive models also have separate heads and cartridges).
   Previously, I liked the piezoelectric technology better: the paint was more "imprinted" into the paper, which is why it was less smeared. Now I do not know.
3. piezo 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 specifically happen if you do not watch the print - for example, the HP's head slows down a lot - 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 look after the printer when printing, then it is better to take a piezo.
   On the other hand, this can only happen if the installation is incorrect, after changing cartridges during the first printouts, or if you stop checking the ink level yourself.
   Yes, and the cost of the head is tolerable (and it is also a consumable), within two thousand. With spare parts for a laser, this is not comparable at all.

The development of thermal technology began in 1984 by HP and Canon. At first, the business was slow and required a lot of money. And only in the 1990s. managed to achieve an acceptable level of quality, speed and cost. Later to HP and Canon for further work on thermal printers Lexmark joined in, leading to today's high-resolution printers. As the name suggests, thermal (or electrothermal) jet formation is based on an increase in the temperature of liquid ink under the action of an electric current. This temperature increase is provided by a heating element located in the ejection chamber. At the same time, some of the ink evaporates, excess pressure quickly builds up in the chamber, and a small drop of ink is ejected from the ejection chamber through a precision nozzle. Within one second, this process is repeated many times.

Thermal droplet ejection system . Print quality, speed and efficiency are determined by many factors, but the main factors that determine the behavior of ink at the required temperatures and pressures are the configuration of the ejection chamber, as well as the diameter and accuracy of the nozzle. The behavior of the ink during heating and ejection from the nozzle, along with the characteristics of the ink itself (its viscosity, surface tension, ability to evaporate, etc.), is also influenced by the characteristics of the channel leading to the nozzle and the exit point to the nozzle. Of great importance for ensuring the correct ejection of ink from the nozzle are also the nature of the change in the ink meniscus in the nozzle after ejection and the refilling of the ejection chamber.

The mechanics of creating a thermal jet . Stages of drop formation and ejection.

Stage 1 - Building up overpressure . The formation of a thermal ink jet begins in the print head of the cartridge. An electrical impulse generates a heat flux on the heating elements, equivalent to more than two billion watts per square meter. This is about 10 times more than the flow on the surface of the Sun! Fortunately, since the duration of the thermal pulse is only 2 millionths of a second, although the temperature at this time increases at a rate of 300 million degrees per second, the surface of the heating element only has time to heat up to approximately 600 ° C during this time.

Stage 2 - Formation of the ink drop . Since the heating is extremely fast, in reality the temperature at which the ink can no longer exist as a liquid is reached only in a layer with a thickness of less than one millionth of a millimeter. At this temperature (approximately 330°C), a thin layer of ink begins to evaporate and the bubble is forced out of the nozzle. The vapor bubble is formed at a very high temperature, and therefore the vapor pressure in it is huge - about 125 atmospheres, i.e. four times the pressure created in modern gasoline internal combustion engines.

Stage 3 - Cooling the chamber. Such a bubble, which has tremendous energy, acts like a piston, ejecting ink from a nozzle onto the page at a speed of 500 inches per second. The resulting drop weighs only 18 billionths of a gram! By commands from the printer driver, 400 nozzles can be activated simultaneously in any combination.

Stage 4 - Filling the chamber . It takes less than 100 ppm of a second to refill the ejection chamber, after which the chamber is ready for use again. In Lexmark thermal inkjet printers, the cycle, including the formation and ejection of an ink drop, cooling and reheating of the camera, can be repeated up to 12 thousand times per second.

Impressive Facts . Here are some data characterizing the process of bubble formation. Heat flux at the surface:
heating element = 109 W/m2
Sun = 108 W/m2
Heating in a thin layer up to 600°C
Melting point of aluminum = 660°C
Initial pressure in the bubble - 125 atm
This is the pressure in the ocean at a depth of 1000 m

Differences between "bubble jet" and "ink jet". Although inkjet technology was originally created by HP and Canon, the term "bubble jet" has now become associated with Canon, almost separate from the "ink jet" technology being developed by Lexmark and HP. However, in reality, both of these terms refer to almost identical systems. The only major difference between the two is that in Canon's "bubble jet" system, the ink evaporation and bubble formation process vector does not coincide with the direction of the axis passing through the heating element and the nozzle, but is oriented at an angle of 90 ° to it.

Ink cartridges. The reservoirs from which ink is supplied to the print head can be divided into two constructive types. Firstly, a monoblock system is widely used, combining an integrated ink tank and an ejection unit. It has the advantage that the print head is replaced every time the ink tank is changed, helping to maintain high print quality. In addition, it is simpler in design and easier to perform replacements. In the second, more complex system, the print head is separated from the ink reservoir, and only this reservoir is replaced when it is empty.

Manufacture of printheads. The manufacture of a print head is a complex process carried out at the microscopic level, where the measurement accuracy is measured in microns. The main materials used for the ejection chamber, ink channel, electronic control circuit and heating elements are similar to those used in the semiconductor industry, where the thinnest conductive metal and insulating layers are precision laser processed. This technology requires a lot of investment in both development and production, and this is one of the main reasons why very few companies venture into this area.

An example of a monobloc cartridge. The foam in the ink reservoir acts as a sponge to absorb liquid ink so that ink is continuously supplied to the print head, and there is neither unwanted gravity leakage from the cartridge nor ink leakage from the print head itself. On the base of the monobloc cartridge are electrical contacts and a print head - a key element of the entire inkjet printing process; ink is supplied to the print head through a set of channels coming from the reservoir.

Location and number of nozzles . The printhead is a collection of many micro-assemblies consisting of ejection chambers and associated nozzles, arranged in a checkerboard pattern in order to increase the vertical density of the nozzles. With this arrangement of nozzles, the number of nozzles at a distance of half an inch (about 1.27 cm) can reach 208, as is the case, for example, in the black cartridges of the Lexmark Z models, so that a resolution of 1.44 million dots can be achieved.

prospects. The quality of a print is determined by many factors, but the main ones are dot size, vertical dot density, and frequency of droplet ejection through the nozzle; it is these indicators that are the main criteria for further work on printheads, whether they are thermal or piezoelectric heads. Thermal heads have some advantages over electromechanical heads because the key manufacturing technology is similar to that used in the manufacture of microprocessor chips and other semiconductor electronics products. Rapid progress in these areas is benefiting thermal technology and it can be expected that even higher resolutions and better performance will be achieved in the coming years. high speed print.

Advantages and disadvantages. Thermal inkjet printing has several advantages over competing piezo technology. For example, simplicity of design and close analogy with semiconductor manufacturing: this means that the marginal cost of production here will be lower than for a competing technology. The configuration of the ejection chambers allows the nozzles to be placed closer together, which makes it possible to achieve higher resolution.

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

Continuous inkjet printing

The pressurized dye enters the nozzle and separates into droplets by creating rapid pressure fluctuations produced by some electromechanical means. Pressure fluctuations cause a corresponding modulation of the diameter and speed of the dye jet exiting the nozzle, which is separated into individual drops under the influence of surface tension forces.
This method makes it possible to achieve a very high rate of droplet creation: up to 150,000 droplets per second for commercial systems and up to a million droplets for special systems. An electrostatic deflection system is used to control the flow of droplets. Drops flying out of the nozzle pass through a charged electrode, the voltage on which changes in accordance with the control signal. The flow of drops then falls into the space between two deflecting electrodes having a constant potential difference. Depending on the previously obtained charge, individual drops change their trajectory in different ways. This effect allows you to control the position of the printed dot, and its presence or absence on paper. In the latter case, the drop is deflected so much that it enters a special trap.
Such systems allow you to print dots with a diameter of 20 microns to one millimeter. A typical dot is 100 microns, which corresponds to a droplet volume of 500 picolitres. 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 flow of drops provides for the possibility of direct control of the process of creating a drop at a certain time. Unlike continuous systems, there is no constant pressure in the ink volume, and when a drop is needed, pressure pulses are generated. Controlled systems are fundamentally less complicated to manufacture, but their operation requires a device for creating pressure pulses approximately three times more powerful than for continuous systems. The performance of controlled systems is up to 20 thousand drops per second for one nozzle, and the droplet diameter is from 20 to 100 microns, which corresponds to a volume of 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, each nozzle is equipped with a piezoelectric element 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 is compressed and unclenched, squeezing out a drop of ink through the nozzle. A similar drop generation method is used in Epson inkjet printers.
A positive feature of such inkjet printing technologies is that the piezoelectric effect is well controlled by the electric field, which makes it possible to accurately vary the volume of the resulting droplets, and therefore to a sufficient extent affects the size of the resulting spots on the paper. However, the practical use of drop volume modulation is hampered by the fact that not only the volume, but also the drop velocity changes, which causes point positioning errors when the head moves.
On the other hand, the production of printheads for piezoelectric technology turns out to be too expensive in terms of one head, so in Epson printers the printhead is part of the printer and can be up to 70% of the cost. total cost the entire printer. The failure of such a head requires serious service.

For implementation thermal jet method, each of the nozzles is equipped with one or more heating elements, which, when a current is passed through them, heat up to a temperature of about 600C in a few microseconds. The gas bubble that occurs during sudden heating pushes a portion of the ink forming a drop through the outlet of the nozzle. When the current stops, the heating element cools down, the bubble collapses, and another portion of ink comes from the inlet channel in its place.
The process of creating drops in thermal printheads after a pulse is applied to a resistor is almost uncontrollable and has a threshold dependence of the volume of the evaporated substance on the applied power, therefore, here, dynamic control of the droplet volume, in contrast to piezoelectric technology, is very difficult.
However, thermal printheads have the highest performance to unit cost ratio, so the thermal inkjet printhead is usually part of the cartridge and when the cartridge is replaced with a new one, the printhead is automatically changed. However, the use of thermal printheads requires the development of special inks that can evaporate quite easily without igniting and are not subject to thermal shock damage.

Lexmark print head

The print head of a black cartridge of 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 printhead that contained 104 monochrome nozzles and 96 color nozzles.
Lexmark inkjet printheads, starting from the 7000 series, use printheads manufactured using laser nozzle-piercing technology (Excimer, Excimer 2). The first models of printheads contained 208 monochrome nozzles and 192 color nozzles.
For the Z51 model and the older model of the Zx2 and Zx3 family, a print head with 400 nozzles was developed. In the Z51 model, only half of the nozzles were used, and the rest worked in hot standby mode, when, as in the following models, all nozzles were simultaneously activated.
The lower and middle models of the Zx2 family use cartridges that are a modification of standard high-resolution cartridges, and the lower and middle models of the Zx3 family use new models of Bonsai cartridges.
Do not leave the print head nozzles open for a long time. If the nozzles are left open, the ink in them dries up 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.

Print head specifications

Period of meniscus formation:
This is the amount of time it takes for the chamber to refill with ink. It determines the operating frequency of the print head (from 0 to 1200 Hz).

Drop speed:
Low speed results in a continuous dot arrangement.
High speed results in spatter and streaks.

The mass of a drop is determined:
Heating element size.
Nozzle diameter.
Back pressure.

It has been noticed that in conventional inkjet printers, a drop of ink falling on the paper takes the form of a small triangle, so the lines look jagged on closer inspection. This is due to the fact that the drop is deformed in flight, and when it comes into contact with paper, it spreads. This is especially noticeable in low mode when printing economically. Lexmark offers printers with a new, advanced printing technology that balances nozzle shape and head speed so that ink droplets appear as regular strokes. This allows you to make the lines smooth, and the print quality is almost indistinguishable from laser printing. In addition, this shape of the spot avoids whitish streaks on the print.

What is ink?

Each manufacturer of inkjet printers develops and improves its ink composition, which is most adapted to the technology produced. At Lexmark, the main components of inkjet inks are:
- Deionized water (85-95% of total volume)
-Pigment or dye
- Solvent (for pigments)
- Humidifier (Humectant)
-surfactant (Surfactant)
- Biocide
-Buffer (pH stabilization)

Pigment or dye. Pigment-based inks (black only) are made from solid particles in a liquid. When such ink gets on paper, the liquid evaporates and is partially absorbed, and the powder sticks to the surface without spreading over it. Therefore, pigment-based inks are waterproof, have poor penetration into paper fibers, but are sensitive to light.
Dye-based inks are generally colored inks. The dye is soluble in water and is absorbed along with it into the thickness of the paper when it dries. Such ink dries faster than pigment ink, is light-resistant, but on the other hand gives more irregularly shaped spots on average than the latter.
Humidifier. The concentration of the humectant affects the viscosity of the ink. This setting should be optimal for the given ink formulation and the print head it will be used with. 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 much viscosity leads to a long meniscus formation time, which degrades the printing speed. Typically, ink viscosity is a key parameter in determining the geometric channels in a printhead.
Surface tension affects the wettability of ink on all surfaces it comes into contact with, from the reservoirs in the cartridge to the surface of the paper. Too low static surface tension causes the ink to dry faster on the paper surface, but the average drop volume when the ink is squeezed out of the nozzles is too high. If the surface tension is too high, it will increase the drying time and therefore reduce the image stability when printing.
Acidity level(PH) low acidity leads to low solubility of the ink components in water and, as a result, poor water resistance of the image. The standard acidity level is considered to be 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 cells for ink of 3 different colors. The monochrome cartridge contains only one black ink cell.

Inks and colors

The correct transfer of the color of an image to paper is a highly technological process that requires taking into account a considerable number of factors, including a 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 thin spectral composition, otherwise the colors obtained by mixing will be “dirty”. After drying, the ink must remain transparent, otherwise there will be no natural mixing of colors.
An important factor is also resistance to fading, environmental friendliness and non-toxicity.
It is believed that the optimal composition of the ink is already known. In almost all manufacturers, they represent a suspension of very small particles of mineral pigment. With color 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 so-called color tables, which are used to convert color space, in which the original image was created, into some “deformed” color space, which takes into account the peculiarities of rendering colors on paper with ink. Usually, separate color tables are built for each type of paper and are optimized for each individual type of ink and printhead.

Lexmark Drivers

Lexmark printer drivers are ready to print when installed, with automatic object recognition to get good quality images without prior adjustment. Auto mode also allows you to achieve optimal combination document quality and speed. Setting the driver for special paper or selecting color tables for a more contrast or natural tone of the image is very easy in the Document Quality driver settings section.
Lexmark's Color Fine 2 Series drivers automatically detect the cartridge type, making it much easier to change all systems to a different cartridge type or change from an old one to a new one. A characteristic feature of this series of drivers is their ability to work with images in sRGB and ICM standards.
sRGB standard proposes that a device-independent color space is used to describe a color image, which is built into Microsoft OC or Internet tools. Using the standardized RGB description of the UTI-R BT.709 color space, this standard allows minimizing the transfer of additional system information associated with the color profile of the equipment on which the image was created along with the image. In the system part of the file with the image, only a reference is given to the standard in which it was created, and the destination position is actively used by the description of the color space provided by the operating system.
ICM standard allows you to more accurately define the variety of generation devices and the display of color images by using color hardware profiles for each type of image generating and display devices. However, this approach implies that the system information associated with the profile of the equipment on which the image is created is transmitted 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 image points of saturated color, so in order to obtain pale shades, ink drops need to be applied quite infrequently. This causes the spots to be so far apart when very light tones are reproduced that graininess becomes noticeable, and there is also a problem with reproduction in high tones.
One of the radical ways to solve this problem is to use additional light-colored inks. In this case, dark tones are obtained by filling with clarified ink. The cartridge with such ink usually replaces the second cartridge (black) and contains clarified Cyan, clarified Magenta and black inks. A light yellow tone is not used, since this color is perceived by the human eye without much difference as yellow.

In a word, all the features of laser technology indicate its versatility and high efficiency - you can use such a printer both in the office and at home. The brilliant speed/quality ratio makes laser printers and MFPs indispensable in both large and small offices, as well as wherever large volumes of documents need to be printed. For example, students or educators who often print their work will be happy to be able to do more and get better quality materials.

For high speed color printing in enterprises, Konica-Minolta laser printers and MFPs can be recommended. Monochrome laser printing solutions for small and medium-sized offices should be found among Brother MFPs or Hewlett-Packard's line of budget LaserJet printers.

Laser technology involves a complex and finely organized printing mechanism - it uses static electricity and an optical system to create an invisible electrostatic prototype of the future print, and then "fill" it with toner particles and fix the result on paper.

First of all, the charging roller comes into action - it evenly covers the surface of the photoconductor with a negative charge. After that, the printer controller determines the areas on the surface of the drum that form the image. These areas are "illuminated" by the laser beam and the negative charge on them disappears.

Next, the feed roller gives the toner particles a negative charge and moves them to the developer roller, where they pass under the doctor blade, spreading evenly over the surface. Now, when in contact with the photoconductor, they fill with themselves those areas where there is no negative charge.

As a result, a visible image is formed on the drum - all that remains is to transfer it to paper and fix it. First, the paper is fed onto the transfer roller and receives a positive charge. When in contact with the photoconductor, it easily draws toner particles onto itself. Particles stick to paper only due to static electricity; to secure them in place, the sheet is processed in the fuser. This is the name of a system of two shafts, one of which heats the paper, and the other firmly presses it from below, allowing the molten toner particles to be imprinted deeper into the surface of the sheet.

Laser printers and MFPs are very sensitive to the quality of consumables, so experts unanimously recommend using only original toner cartridges. Genuine toner has very small particles, which allows you to achieve high print quality and extend the life of the printer. Counterfeit toner can be compared to broken coal - it scratches the surface of the photoconductor and the internal parts of the printer with which it comes into contact.

The main disadvantages of laser printing are the high cost of the devices themselves and their cartridges, increased energy consumption, and ozone emission. Due to the more complex internal structure, laser devices are not as compact as inkjet devices.

The release of ozone during laser printing is inevitable, since the laser beam, when it comes into contact with air, splits oxygen molecules. And yet, manufacturers manage to reduce the volume of such emissions, minimizing the negative impact on humans. If you're looking for laser quality but are concerned about ozone, consider LED technology - it's similar to laser in many ways, but uses LEDs instead of a laser.

LED printing

The print quality is excellent - no graininess, and light and dark shades look equally natural. Laminated prints are resistant to fading and various external influences (water, fingerprints).

In addition to Canon, the release sublimation printers are engaged Sony and Samsung. The Sony DPP-FP55 features a large preview LCD, allows you to apply various effects and patterns to images (such as printing calendars), and uses proprietary Super Coat II lamination technology that can maintain original print quality for years to come.

Samsung SPP 2020B has its advantages: built-in Bluetooth module for mobile printing, simple but stylish design and the lowest cost per print in its class.

Users who have never experienced this technology often wonder why photos printed on a sublimation printer at 300x300 dpi look better than those printed on a laser printer at a much higher resolution. The secret is that for printing photographs, the priority parameter is not resolution, but lineature - the density of the printing screen.

Modern dye-sublimation printers such as the Canon Selphy have higher rates than many high-end photo inkjet printers. Hence the result - a dense raster structure, maximum clarity and, at the same time, smooth contours.

But what is the technological feature of sublimation printing? In this case, sublimation is the transition of a dye from a solid state to a gaseous state, bypassing the liquid state. The system is implemented quite simply: inside the printer are a heating element and a special film with a dye. A sheet of paper is placed between them. When heated, the ink evaporates from the film and enters the pores of the paper that have opened from heating. Further, the paper cools slightly, and its pores close, so that the image is firmly fixed on the sheet.

The peculiarity of sublimation technology is also that the paints of three colors are applied not at the same time, but in turn, so the print goes in three passes. An additional run for laminating pages is also possible. Lamination allows you to additionally protect prints from external negative influences and at the same time give them an attractive glossy sheen.

Vulnerability of sublimation technology - prints sensitivity to ultraviolet light. Now this problem is being overcome by developing a new type of ink. The main disadvantages of portable photo printers can be considered low speed and small print format. Ideal for holidays, but not serious for the office, as sublimation printers have a narrow specialization - photo printing, and, moreover, are not designed for a large flow of tasks.

Large volumes and high speed printing, combined with high reliability and ease of maintenance - the advantage solid ink printers.

Solid ink printing

Among the most relevant modern technologies printing, solid ink offers particularly wide possibilities for business use. Due to its cost-effectiveness and high-speed qualities, the solid ink printer is ideal for working with large volumes of color documents and provides high-quality high-speed printing, not always available even to the best laser devices. So, for Xerox ColorQube printers, the print speed can reach 85 ppm, and the first print is out in just 5 seconds.

The key feature of solid ink printers is that they are initially focused on high-speed color printing and at the same time the thousandth print is as clear and bright as the first one, because the print quality in this case does not depend on the number of printed pages. In addition, such printers print on paper of different weights with the same success.

A striking example of a modern solid ink printer is the Xerox Phaser 8560. This model is designed for medium workgroups. Applying four colors of ink at the same time allows you to achieve high speed color printing. The piezo elements of the nozzles provide a more intense droplet emission than inkjet printers. Melted ink is baked on paper instantly, without spreading or spilling, and is distinguished by enviable durability. During the passage through the machine, the paper does not have time to get very hot, so you can print the second side of the sheet immediately - without prejudice to the first.

Dry ink sticks - sticks - correspond to different colors of the CMYK system. They are easy to use and store: do not stain hands and clothes, do not dry out. The bar of each color, designed for a specific printer model, has its own unique shape, which allows you to avoid errors when installing it in the printer.

It is also worth noting the high reliability of solid ink devices - the design of the printing mechanism is very simple and contains a minimum of moving parts, which reduces the risk of breakage. The image drum in a solid ink printer is replaced approximately every five years. Modern models are equipped with a wide print head that requires little or no movement to cover the full width of the photoconductor. Little movement is required from it only at resolutions above 2400 dpi. Thus, the printing speed is high, and the wear of components is minimal.

Once upon a time, solid ink printers were considered very expensive, but by now their cost has dropped markedly. The printer has minimal impact on environment and does not emit ozone. It is also important that color solid ink printing costs almost half the price laser.

Preparation of solid ink printers for work takes place in several stages. First, the printhead tanks are heated to 140-180°C. At the same time, the melting of solid ink on the ceramic plates begins, as well as the heating of the metal photoconductor. Molten ink flows into the hot cavities of the print head. When the containers are full, the heating of the plates stops.

The next step is to clean the print head nozzles with a vacuum pump cleaning unit. Sliding close to the nozzles of the head, the cleaning unit pumps air out of them and absorbs some of the melted ink. Returning to his original position, he drains the hot ink into a special waste tray. There they harden again. The ready-to-use device is kept in a “warm state” so that the melted ink does not cool and solidify again.

The disadvantages are quite obvious. Each time the printer is turned on, a small amount of ink is emitted and about 5% of each cartridge is wasted. The warm-up process itself takes about 15 minutes, so frequent restarting of the device costs a pretty penny. Ideally, the printer should not be turned off at all - it is better to keep it in working condition all the time, just like the server. In the enterprise, this will not be difficult, especially since the device consumes very little energy in sleep mode.

If, however, the power suddenly turns off during printing, the nozzles may become clogged with solidified ink and you will have to clean it. Therefore, when the power supply is unstable, it is worth connecting the printer through a UPS (Uninterruptible Power Supply).

Solid ink documents are susceptible to temperatures over 125°C, so if you are preparing letterhead that will later be run through a laser printer, the ink may not withstand contact with the thermal roller of the laser fuser.

Another disadvantage of solid ink technology is that in color printing, light areas of a color image have a noticeable raster structure. The reason is that the ink drops are clearly fixed in place, and the nozzles are widely spaced. Therefore, despite good color reproduction, solid ink devices are not suitable for photo printing.

conclusions

So, let's summarize our conversation, once again briefly listing the features and scope of each of the printing technologies discussed above.

inkjet printing- finds application both in professional polygraphy, and in house conditions or at small office. It is used not only in desktop printers and MFPs, but also in plotters, as it is best suited for printing high-resolution color materials, including: photographs, advertising and souvenirs, geographical maps and technical documentation (CAD, GIS). Allows you to print on the surface of optical discs, which is very convenient for designing a CD / DVD collection. Another important advantage of inkjet devices is affordable price. The main disadvantages are low speed and high cost of printing; relatively high cost of ownership.

laser printing- the ideal choice for those who print often and in large quantities. A smart choice for the office, especially for medium to large workgroups. The most important advantages of laser devices are: high speed and low cost of printing, a good level of clarity and detail of images, resistance to high loads, “long-playing” toner, which, unlike liquid ink, does not spread and is stored for a long time. Disadvantages of the technology: the relatively high cost of devices, the release of ozone, the increased concentration of which worsens health. In addition, laser devices are not as compact as inkjet ones.

LED printing- in many respects it is similar to laser, it has the same advantages, but instead of a laser beam it uses an LED ruler, which reduces the cost of ownership of the device and completely eliminates the release of ozone. In LED printers using single-pass tandem technology, the speed is greatly increased and the quality of color printing is improved. Another technology, the ProQ2400, brings color print quality closer to photographic quality by setting different intensities for each color. The LED printer is really reliable in operation and is great for modern office especially for document-intensive organizations. The main disadvantage of the technology is that it is impossible to create two absolutely identical LED strips, which means that prints made on two printers of the same model will not be 100% identical. The difference is imperceptible to the eye, but with accurate measurements it is detected. In addition, in terms of point positioning accuracy, the LED ruler is still slightly inferior to the laser beam.

sublimation printing- the dream of an amateur photographer and vacationer. Whether you want to share vivid holiday memories with your loved ones or even create postcards and calendars from your photos, a sublimation printer will help you achieve what you want even without a computer. You can print photos directly from USB sticks, digital cameras and memory cards. Some sublimation printers are equipped with Bluetooth adapters, so you can print directly from mobile phone. And if you decide to connect to a computer, Wi-Fi will help you. Creating juicy, realistic photos with an excellent level of clarity does not require you to additional knowledge and effort. But do not forget that the scope of sublimation technology

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7 years ago

Some of the discoveries or inventions that have long become familiar, over time, acquire a variety of beautiful myths and legends.
One of these stories tells about an employee of a small research laboratory that belonged to a large computer firm. After a sleepless night working on a capricious new design for some electronic contraption, this employee inadvertently placed a soldering iron next to a syringe filled with rosin (I would like to ascribe that it contained ink, but it is not). Naturally, as a result, overalls were spoiled, but most importantly, the idea of ​​thermal inkjet printing arose. A stained white coat went to the dry cleaners, and inkjet technology, through the efforts of Canon, Hewlett-Packard, Epson, Lexmark and other companies, came to offices and homes, striking with its affordability and colorfulness.

Why an inkjet?

In the past few years, the computer industry has experienced a real ink boom. Inkjet printers for many users are the most affordable and versatile printing devices. The images obtained on them are in many cases superior in quality to printed copies, and the maximum print speed has already come close to the performance indicators of lower models of laser printers. Comparable to amateur photos from mini-labs, full-color photorealistic inkjet printing has become the main trump card of inkjet printer manufacturers in the fight to attract new customers.

In pursuit of the buyer and the envy of competitors, the droplet size is constantly decreasing and new technologies are being developed to improve color reproduction. From the new names and logos, the head is already spinning. Naturally, the most inquisitive question arises: are all the principles and ideas that each of the manufacturers is proud of so unique?

In proud loneliness

For quite a long time, two camps have formed in this sector of the market. In one, Epson alone rules the ball with piezoelectric technology, and in the other, an entire alliance of adherents of “boiling ink” has gathered.

The piezoelectric printing method is based on the property of some crystalline substances to change their physical dimensions under the influence of an electric current. The most striking example is the quartz resonators used in many electronic devices. This phenomenon has been used to create a miniature pump in which a change in voltage causes a small volume of ink to compress in a narrow capillary channel and to be ejected instantly through a nozzle.

The printhead of a piezoelectric inkjet printer must be highly reliable, because, due to its rather high cost, it is almost always built into the printer and does not change when a new ink cartridge is installed, as is the case with thermal inkjet printing. This design of the piezoelectric head has certain advantages, but at the same time there is a constant risk of damage to the printer due to an air bubble in the ink supply system (which can happen when changing the cartridge) or ordinary downtime for several weeks. In this case, the nozzles become clogged, print quality deteriorates, and restoration of normal modes requires qualified service, which is often impossible to carry out outside the service center.

Stay away from the team

While Epson went its own way, periodically surprising the computer community with another breakthrough, other players in the inkjet printing market were no less successful in using a print head of a different design. Most of them consider their developments to be unique, although their essence is trivially simple, and the difference often lies only in the name.

So, Canon uses the term Bubble-Jet, which can be loosely translated as "bubble printing". The rest did not fence the garden and agreed with the more familiar phrase "thermal inkjet printing."

Thermal inkjet printers work like a geyser: inside the ink-limited chamber, a miniature heating element creates a bubble of steam that instantly expands, pushing a drop of ink onto the paper.

Using this technology, it is not difficult to obtain miniature printing elements located at a high density, which promises developers a potential increase in resolution with a solid margin for the future. However, thermal inkjet printing also has flip side. Due to the constant temperature difference, the print head is gradually destroyed, and as a result it has to be replaced along with the ink cartridge.

More names - loud and different!

Bubbles are bubbles, and simple pictures have not surprised anyone for a long time. So you have to fight for every picoliter in a drop, for every shade on paper. But there are really not so many ways to improve the quality of the final image. the most obvious and affordable option was to increase the number of ink colors. In addition to the four basic colors (black, blue, crimson and yellow), many manufacturers have added two more - light blue and light crimson. As a result, it became possible to reproduce lighter shades without reducing the density of dots applied to the paper, which made it possible to make the raster structure of the image in light areas, where it is especially well distinguishable, less noticeable. Canon called this technology PhotoRealism, Hewlett-Packard called PhotoREt, and Epson called Photo Reproduction Quality.

But progress, stimulated by competition, does not stand still. The next step towards the ideal was made by reducing and dynamically changing the size of the ink drop, and with it the end point on the paper. By controlling the amount of "portion" of ink applied to the paper, you can achieve lighter shades without increasing the distance between dots. This makes it possible to make the bitmap structure even less visible.

Without additional tricks and significant change technological process only Epson could achieve a similar effect. The fact is that the principle of operation of the piezoelectric head allows you to control the size of the drop by changing the amount of control voltage applied to the piezoelectric element. This technology is called Variable Dot Size. Well, the adherents of bubble printing had to seriously work on changing the design of the nozzles. Each of them placed several heating elements of different power.

By turning them on one at a time or all at the same time, it is possible to obtain droplets of various sizes, as is the case in modern thermal inkjet printers. Canon dubbed its developments in this area Drop Modulation, while HP used a ready-made name with additional indices - PhotoREt II and PhotoREt III. In addition to the ability to control the size of the drop, there was also the possibility of successively applying several drops to the same point on the surface of a sheet of paper.

But the print quality depends not only on the technical perfection of the design of the printer itself, but also on other equally significant factors.

Behind the line of the jet front

With an increase in resolution and printing speed, it turned out that the pursuit of improving these characteristics in itself could not give a significant gain, if the image carrier, that is, paper, was not improved. It would seem, what could be simpler than paper? But it was not there! Any "cunning" technologies will be powerless if you put plain office paper in the printer tray.

A beautiful sheet of A4 format, from the sight and smell of which any laser printer begins to purr with pleasure, turns out to be completely unprepared for the streams of multi-colored ink erupted at it from hundreds of nozzles.

The surface of ordinary paper has a fibrous structure, which is due to the technology of its production. As a result, miniature, strictly sized drops begin to spread over the surface in the most unpredictable way. In this case, it does not matter at all what kind of printing is used - thermal or piezoelectric. One solution to this problem is the use of pigment ink, which is a suspension of dispersed particles in a colorless liquid carrier, since solid particles cannot penetrate into the inner layers and spread through the fibers of the paper.

Pigment-based inks make it possible to obtain bright and saturated shades, but they also have certain disadvantages, in particular, low resistance to external influences.

Inkjet printing technology is such that the best results can only be achieved using special paper. Photos on plain paper look faded and less clear. Specially coated paper and so-called photographic paper have several special layers, unlike regular paper. Prints on it are almost indistinguishable from photographs obtained by printing using a chemical photoprocess.

Plain budget paper for inkjet printing, as a rule, has a density of 90-105 g/m 2 , relatively thin thickness and excellent whiteness. Due to the special processing of the front or both sides, such paper is more resistant to the vagaries of ink and prevents them from spreading and penetrating deep into the sheet.

Special photo paper with a glossy or matte surface usually has a density of up to 200 g/m 2 and is a multi-layer product of modern technology. Each of the layers performs certain functions.

The bottom layer is the base that provides strength and rigidity to the document. The next layer acts as an optical reflector, giving the image brightness and whiteness. Next is the main bonding ceramic or plastic layer, which constitutes a plurality of vertical channels without long fibrous formations along the surface of the sheet and provides the necessary ink density at the printed dot. The last, glossy or matte protective layer is applied to the absorbent, giving the surface strength and protecting it from external influences.

During the printing process, ceramic particles absorb ink, preventing it from spreading over the surface. As a result, the shape of the points and their orientation remain unchanged. In addition, you can not be afraid of accidental moisture ingress, since deep and strictly vertical microcapillaries minimize the likelihood of spreading.

Special paper for inkjet printers has become a panacea for many ills, but, unfortunately, quite expensive. I want to, of course, but ... And it's worth spending money to compare "heaven" and "earth" at least once.

ComputerPress 11 "2001