Piezoelectric jet. Inkjet printing technology. Piezoelectric printing advantages and disadvantages

Inkjet technology appeared in the mid-1980s as a result of an attempt to get rid of the shortcomings of the two dominant printing methods at that time: dot matrix and laser (electrographic). Laser printing was unacceptably expensive, and color was not yet dreamed of (and even now, although color laser printers have become available, they have no chance to bypass inkjet printers in the field of photo prints). And inkjet printing emerged as a cheap alternative for printing office documents, devoid of the disadvantages of dot-matrix printers - slow, noisy and producing low-quality prints.

The idea, which, apparently, almost simultaneously (around 1985) came to the minds of engineers from Hewlett-Packard and Canon, was to replace the needle that hits the paper in dot-matrix printers through the ink layer on the ribbon with a drop of liquid ink. The volume of the drop should be calculated so that it does not spread and creates a point of a certain diameter. real life this technology was obtained when they came up with a convenient way to form a dosed drop - thermal.

The thermal inkjet printing method is virtually monopolized Canon companies and Hewlett-Packard, which hold most of the technology's patents, the rest of the companies just license it with their own little tweaks. While HP uses the term "thermal inkjet" (thermal ink-jet) printing method, and Canon prefers the term "bubble-jet" (bubble-jet).

Although there are differences between them, they are fundamentally identical.

On fig. 1 shows the process of thermal inkjet printing in the form of a conditional cinegram of the cycle of the nozzle (sometimes called ejectors). A miniature heating element is built into the chamber wall (highlighted in red in the top frame), which heats up very quickly to a high temperature (500 °C). The ink boils (second frame), a large vapor bubble forms in them (the next two frames) and the pressure rises sharply - up to 120 atmospheres, which causes the ink to be pushed out through the nozzle at a speed of more than 12 m / s in the form of a drop with a volume of about 2 picolitres (this is two thousandths from a billionth of a litre). The heating element is switched off by this moment, and the bubble collapses due to pressure drop (bottom frames). Everything happens very quickly - in a few microseconds. The ink is fed into the nozzle due to capillary forces (which is much slower), and after filling the nozzle with a new portion, the system is ready to work. The entire cycle takes approximately 100 ms, that is, the frequency of drops is 10 kHz, and in modern printers - twice as much.

Such an autonomously controlled nozzle is part of the print head located on a carriage moving across the sheet, similar to the print unit of a dot matrix printer. With a nozzle diameter of 10 microns, the placement density is 2500 nozzles per inch; in one head there can be from several hundred to several thousand nozzles. In modern high-speed devices, fixed heads began to be used - in order to eliminate the slowest stage in the entire process of the transverse movement of the carriage. For example, HP produces high-performance photo kiosks in which the heads are arranged in blocks across the entire width of the sheet.

On Canon printers, the thermal element is located on the side of the camera (as in Fig. 1), while on HP (and Lexmark) it is on the back. Perhaps this difference is due to the original ideas: according to corporate legend, a Canon engineer dropped a soldering iron on a paint syringe (that is, the syringe heated up from the side), and HP researchers borrowed the principle from an electric kettle, which is heated from the end. Like it or not, the lateral arrangement allows Canon to mount two thermal elements per nozzle, which improves performance and manageable droplet size, but complicates and increases the cost of design.

Canon's more expensive "bubble" heads are reusable and built into the printer. HP heads are easier to manufacture, because they were traditionally built directly into the cartridge and thrown away with it. This is much more convenient, as it guarantees print quality (the head simply does not have time to work out the resource) and high reliability of the assembly. However, with this approach, improving the heads leads to a rise in the cost of cartridges, so many modern HP printers have separate heads, like Epson or Canon. For example, the Photosmart Pro B9180, today's flagship of HP's "home" photo printers, has replaceable individual heads, while its cheaper analogue, the Photosmart Pro B8353, has cartridge-integrated heads.

Making a request

Brief characteristics of inkjet piezoelectric and thermal inkjet printing technology

Catalog with inkjet piezoelectric printing technology.

The most common printers today are based on inkjet technology: crushed dye droplets are sprayed onto the material. Typically, as in dot matrix printers, the print head moves across the media feed direction to form an image stripe, and then the media shifts to print the next stripe. However, instead of needles, the head has many nozzles for ejecting paint.

In inkjet ink printing technology, two technological branches have developed:

thermal jet, in which the activation of the paint and its release occur under the influence of heating;
piezoelectric, in which the ejection of paint occurs under pressure created by the oscillation of the membrane.

Piezoelectric inkjet technology

Piezoelectric system created on the basis of an electromechanical device and brought to commercial readiness by Epson (subsidiary Japanese Seiko), was first used in Epson inkjet printers back in 1993. Successfully used so far (2011).

Drop ejection system

Piezo technology is based on the property of certain crystals called piezocrystals (an example is quartz crystals in now common quartz crystals). wrist watch), deform under the action of an electric current; thus, the term defines an electromechanical phenomenon. This physical property allows some materials to be used to create a miniature "ink pump" in which a change from positive to negative voltage will cause a small volume of ink to be compressed and vigorously ejected through an open nozzle. As with the formation of an ink jet due to thermal effects, the drop size here is determined by the physical characteristics of the ejection chamber (firing chamber) and the pressure created in this chamber due to the deformation of the piezocrystal.

Modulation, i.e., changing the size of the drop, is carried out by changing the amount of current flowing through the ejection mechanism. As with thermal printers, the frequency of the piezoelectric ejection depends on the potential frequency of the electrical pulses, which in turn is determined by the time it takes for the camera to return to its “quiet” state, when it is filled with ink and ready for the next work cycle. Piezo technology is highly reliable, which is very important because the print head, for purely economic reasons, cannot be part of a replaceable ink cartridge, as in thermal systems, but must be rigidly connected to the printer.

Advantages and disadvantages

For both thermal and piezoelectric systems, the performance is determined by many factors. The ability to change the size of the dot gives piezo technology certain advantages.

On the other hand, piezo technology faces some purely physical limitations. For example, the large geometric dimensions of the electromechanical ejection chamber mean that the vertical density of the nozzles must be less than that of thermal counterparts. Not only does this limit the prospects for further development, but it also means that higher resolution and uniformity in high quality printing requires multiple passes of the print head over the same page.

A stationary printhead is somewhat cost-effective because it does not have to be replaced. However, this advantage is partially offset by the risk of air entering the system when changing the cartridge. This clogs the nozzles, reduces print quality, and requires several cleaning cycles to restore normal system performance. Another limitation so far for piezo systems concerns the use of dye-based inks (dye based inks): when using pigment inks, which are of higher quality, but also have a higher density, there is also a risk of clogging of the nozzles.

prospects

The piezoelectric print head, based on prior technology, has lower development costs, but is noticeably more expensive to manufacture. At present, such advantages of piezoelectric heads as high reliability and the ability to change the size of the droplet are very significant and make it possible to manufacture products of very high quality.

Vertical Resolution

The number of vertical positions is primarily related to the number of vertical nozzles on the print head (lines per inch). Since there are difficulties in creating a print head that includes elements that span two vertical lines at once, two separate rows of nozzles are placed next to each other.

To achieve an acceptable print speed, the maximum number of lines must be printed during each pass of the print head. In this situation, the manufacturer must make a choice between speed (higher print head and maximum number of nozzles) and production costs(minimum number of nozzles).

Horizontal Resolution

Number horizontal positions, the so-called number of drops per inch (dpi), is a function of the frequency at which drops are ejected and the speed at which the print head moves along the horizontal axis. A controlled nozzle at certain moments discretely ejects drops of ink and thus draws a line.

The main difficulty for the manufacturer is the combination of quality (maximum droplets per line) and speed (minimum droplets per line to achieve higher speed). Droplet ejection speed is from 10 to 20 thousand per second. By varying this frequency or the speed of the print head carriage, the optimum horizontal droplet density can be achieved.

Physiological factors and color perception

The perception of the quality of a color document is closely related to the physiology of human vision. Taking into account some individual deviations, the human eye is able to distinguish only colors having a wavelength in the range from 380 nm (violet) to 780 nm (red). Within this spectrum, the human brain can distinguish about a million shades of colors (again with small individual differences).

The perceived color spectrum plays important role when visually evaluating differences in the quality of printed documents: printers capable of reproducing more shades of color will create documents to which human vision will subjectively attribute higher quality.

Number of colors

The total number of possible colors in which an elementary point can be colored corresponds to the number of addressable elementary colors. With three primary colors, you can get eight basic colors: cyan (Cyan), magenta (Magenta), yellow (Yellow), red (Cyan + Yellow), green (Yellow + Cyan), blue (Cyan + Magenta), white and black. .

This system is binary in that color points may or may not be present. If we apply the halftone grayscale principle to these three primaries, thus creating color hues, we get 256 hues for each of the three primaries and thus 256 to the third power of possible color combinations per dot. In other words, this number is greater than what the human eye can discern.

Drop size

The drop size is a complex function of the pressure at which the ink is ejected and the diameter of the nozzle. Usually the droplet size remains unchanged. In certain cases, the size may change and this technology is known as variable droplet printing.

There is a definite relationship between the size of the drop and the size of the dot reproduced on paper. Theoretically, a 20 picolitre drop would make a 60 micron dot (that's approximately one four hundredth of an inch), while a 2 picoliter drop would make a 30 micron dot barely visible to the human eye.

Resolution matrix M

Resolution is the parameter most easily manipulated quantification when determining the print quality of a document. Resolution measures the precision with which dots are placed on the page.

The resolution matrix specifies, for any given point, the total number of possible positions. With dual print head technology, there can be two different matrices, one for color printing and the other for black and white. The matrix allows you to create color levels for each elementary point. Since the resolution is the result of combining two different technological processes, the horizontal and vertical resolution may differ.

The latest advancement in inkjet printing at the time was the horizontal resolution of 2400 dpi, which makes it possible to place 2400 print dots per inch of printed line, which is twice the most common standard today.

Thanks to the precision of printing and the microscopic droplet size of 7 picoliters, such high results are achieved that the image raster becomes completely indistinguishable for human vision. The 2400 dpi resolution is thus intended for printing documents that require the highest possible resolution and impeccable quality.

Because print speed is highly dependent on the number of dots printed, printing at 2400 x 1200 resolution will be slightly slower than printing at lower resolutions.

By the principle of operation, inkjet printers resemble dot-matrix printers, only instead of needles hitting the ink ribbon, ink in inkjet printers is applied directly to the paper with drops of ink through very small holes called nozzles.

Currently, two printing technologies are most widely used in the inkjet printer market: thermal jet, in which the activation of the paint and its ejection occur under the influence of heat, and piezoelectric, in which the ejection of paint occurs under pressure created by the vibration of the membrane.

These are fundamentally different technologies with their pros and cons.

Piezoelectric seal uses the ability of piezocrystals to deform under the influence of an electric current. This allows you to control the size of the drop, the thickness of the jet, and even the speed of ejection of the drop onto the paper. All this allows you to get high-resolution images. Also, the advantage of this technology is the naturalness of color reproduction, and this is one of the conditions for high-quality photo printing. Piezo printing technology invented and patented by the company Epson. Brother uses both technologies.

To date, piezo inkjet printing is the most reliable in relation to others. With proper care, the life of the head is comparable to the life of the printer itself. As a rule, the piezoelectric printhead is stationary, that is, not replaceable with the cartridge. But along with this there are a number of problems, such as a very expensive repair and replacement of the head. In addition, piezo inkjet heads are prone to high ink requirements, the possibility of air infiltration when replacing cartridges, or when ink runs out in the CISS. When printing infrequently, the head nozzles tend to clog or slant.But if you print often, you won't find a better piezo inkjet head.

In thermal inkjet technology, ink is applied to paper by heating, applying temperatures up to 600 C. At the same time, the quality of thermal inkjet printing is an order of magnitude worse than piezo inkjet printing. And all because of the explosive nature of the drop and the appearance of satellites, or satellite drops. Hence the distortion of high-quality images when printed. In addition, as a result of temperature, carbon deposits and scale are formed, clogging the nozzles and leading to a deterioration in color reproduction, the printer begins to streak. In addition, temperature fluctuations contribute to the destruction of the print head, which burns out when overheated. This is the main disadvantage of such PGs. But, as a rule, thermojet PGs are less expensive than piezojet PGs and are combined with a cartridge. As a result, they are replaced more often and at lower financial costs.

Attention! If thermal inkjet cartridges are mistakenly loaded with piezo ink, the consequences can be dire.

Some of the discoveries or inventions that have long since 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 younger 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 exploited 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 be ejected instantly through a nozzle.

The printhead of a piezoelectric inkjet printer must be highly reliable, since, 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 there is a constant risk of printer failure due to an air bubble in the ink supply system (which can happen when changing the cartridge) or normal downtime within a few weeks. In this case, the nozzles become clogged, print quality deteriorates, and skilled service is required to restore normal modes, 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 easy to obtain miniature printing elements located with high density, which promises developers a potential increase in resolution with a solid margin for the future. However, thermal inkjet printing also has a downside. 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 the progress stimulated 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, and HP has already applied finished 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

What are the technologies?

Photo printers have almost universally replaced conventional inkjet models. This is quite natural and is a consequence of technological progress, because all modern A4 inkjet photo printers easily perform the function of universal printing devices, easily coping with printing text and work graphics, as well as printing photographs that are not inferior to photo laboratory products.

In order to understand how the numerous models of photo printers available in stores differ from each other, and which one is more likely to satisfy your need for high-quality photographs, we will talk about the principles of imprint formation in such devices.

Currently, two fundamentally different types of home photo printers are being produced: inkjet and sublimation.

Inkjet photo printing

The first inkjet printer appeared in 1984, and we owe it American company Hewlett Packard. The printing technology of such printers is hidden in the name: the image on paper is formed by jets of ink that are ejected from the print head. By the way, it was inkjet printers that made multi-color printing available, since black ink could be replaced or supplemented with inks of other colors. There are three inkjet printing technologies: Epson and Brother use piezoelectric technology, Canon use bubble technology, Lexmark and Hewlett-Packard use thermal inkjet technology. Each technology has its own zest, but in principle they are all extremely close, and the differences come down to how the ejection of ink drops from the nozzles onto the paper is organized.

Piezoelectric printing technology

Piezoelectric technology is based on the property of piezoelectric crystals to deform when an electric current is applied to them. Piezocrystals act as mini-pumps that eject a strictly defined amount of ink onto paper. Among the advantages of such a system is the possibility of flexible control of the droplet size, which is carried out at the electrical level, which simplifies the production of prints with high resolution. It is believed that the reliability of such a system is significantly higher than that of all other inkjet printing systems. back side advantages - the comparative high cost of the print head, so it is usually installed in the printer, and is not part of a replaceable cartridge. Unfortunately, the piezoelectric head is very afraid of air or counterfeit ink getting into the nozzles. In both cases, you can get clogged nozzles, followed by head replacement, the cost of which can be comparable to the price of the printer itself. In addition, to keep the nozzles in working order, it is necessary to periodically print at least something on such a printer, otherwise ink residues can also clog the nozzles.

However, the new generation of Epson branded ink allows you to forget about this shortcoming. A new generation of Epson DURAbrite pigment inks has also appeared, in which microscopic homogeneous coloring particles are in a liquid polymer. Such ink practically does not blur on any paper, which allows to increase print resolution and have high light and moisture resistant properties.

The quality of piezoelectric printing is extremely high: even inexpensive universal models can produce prints of almost photographic quality with high resolution. Another merit Epson printers is the naturalness of color reproduction, which is especially critical when printing photographs. The only "but": all these advantages are realized only when using branded inks, and master fakes on Russian market great amount. There is only one way out - to buy ink exclusively in large companies that are official dealers of the manufacturer. Do not forget that a broken printer with a "left" cartridge is automatically removed from the warranty.

Thermal inkjet printing technology

Thermal jet technology, which, by the way, was also used in the world's first serial inkjet printer The HP ThinkJet differs in that ink heating is used for printing: in this case, part of the ink is heated, and part, due to excess pressure, is ejected through the nozzle. The process of heating and cooling is repeated several thousand times within one second, the heating temperature is up to 600°C, and the time of the thermal pulse itself does not exceed two millionths of a second. In all modern models HP has implemented proprietary PhotoREt hardware and software technology, which is responsible for the most realistic color reproduction and high speed color printing.

The quality of thermal inkjet printing is very close to the quality of piezoelectric printing, besides, the manufacturing technology of the print head is close to the technology of manufacturing microchips, so the heads are cheaper than piezoelectric ones and, as a rule, are built into a replaceable ink cartridge. Naturally, such a cartridge is somewhat more expensive than just a sealed ink container, but a "non-original" cartridge will no longer be able to completely disable the printer.

Bubble printing technology

Canon's bubble technology is a special case of thermal inkjet printing, in which ink is ejected solely by the gas bubbles formed when the ink is heated, with the heating element located to the side of the nozzle, and not behind it, as in classic thermal inkjet printers. Canon specialists knowingly invested a lot of money in the development of a proprietary print head using FINE technology (Full-photolithography Inkjet Nozzle Engineering), which means “photolithographic production of ink nozzles”: it provides not only high-quality, but also high-speed color photo printing.

The FINE print head uses a micro nozzle system: millions of microscopic ink droplets of a constant volume are applied to the paper every second with the highest precision. Unlike traditional inkjet technology, more ink is applied to the page in less time, which makes it possible to high speed print photos “edge-to-edge” (borderless) up to A4 format.

sublimation printing

A common drawback of all inkjet photo printers, caused by technological reasons, is the banding of the print, which manifests itself in different models to varying degrees. At best, it is imperceptible or barely noticeable, however, if part of the nozzles become clogged or the printer mechanics fail, the print becomes divided into unattractive horizontal stripes. Sublimation printers belonging to the class of thermal printers are completely free from this drawback.

Technology sublimation printing comes from the Latin word sublimare ("lift up") and represents the transition of a substance when heated from a solid state to a gaseous state, bypassing the liquid state.

The principle of operation of a sublimation printer is as follows: when a print job is received, the printer heats the film with the dye applied to it, as a result of which the dye evaporates from the film and is applied to special paper. As a result of the same heating, the pores of the paper open and the dye is clearly fixed on the print, after which the surface of the paper again becomes smooth and glossy. Printing is carried out in several passes, since the three main dyes must be transferred to the paper in the correct combinations: magenta, cyan and yellow.

Since pixelization and banding are completely absent in this case due to the printing technology itself, sublimation printers working with a seemingly modest resolution of 300x300 dpi are capable of producing photographs that are not inferior in quality to prints of inkjet models with a much higher resolution. The main disadvantages of sublimation models are the high cost of consumables and the lack of household models that work with A4 sheets.

Conclusion

Which printer to choose, of course, you decide. For our part, we can suggest that a self-respecting inkjet photo printer works with a resolution of at least 4800x1200 dpi, sublimation - at least 300x300 dpi. Expendable materials inkjet photo printers are cheaper than sublimation ones, but the latter allow you to get a print with a quality much higher than inkjet ones. All modern sublimation photo printers for home printing are still compact models, and cannot boast of printing photos in A4 format, which is aimed at the vast majority of inkjet photo printers. Other than that, both are good.

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