Inkjet mfp epson features printing technology. Modern inkjet printing: the Epson view. Continuous inkjet printing

The heart of Epson inkjet printers is the piezoelectric printhead, a technological masterpiece.

In one second, 20,000 to 30,000 drops of ink are ejected from one nozzle of the Epson MicroPiezo print head.

The printing process involves from 90 to 384 black nozzles, so text documents can be printed at high speed, and for color inks, from 29 to 128 nozzles are used for each color.

Just imagine: printing a color image performs several million operations per second.

Epson MicroPiezo Stationary Printhead

With millions of operations per second, the print head is constantly operating at high efficiency.

This is due to the fact that Epson uses in its inkjet printers not a replaceable, but a stationary print head, the service life of which is equal to that of the printer.

The Epson MicroPiezo printhead has a 12 month warranty.

Epson MicroPiezo Print Technology

The heart of the unique Epson MicroPiezo printhead is a piezoelectric element or piezoelectric crystal.

The principle of operation of the Epson MicroPiezo print head is based on the properties of a piezoelectric crystal, which can be compressed and expanded when an electrical pulse is applied to it.

1. The piezoelectric element is energized.

2. The plate, on which the piezoelectric element acts, begins to bend, creating pressure in the ink reservoir and pushing out the required amount of ink.

3. When the process is complete, the plate bends backward, drawing excess ink into the reservoir.

How does Epson MicroPiezo piezoelectric printing technology work?

The process of ejecting ink droplets is triggered by a short current pulse. Within 5 microseconds, maximum pressure is generated inside the ink reservoir. In the next 5 microseconds after the voltage is removed, the pressure again drops to zero. 1 microsecond \u003d 1 millionth of a second

What quality print parameters does the Epson MicroPiezo printhead have?

1. Minimum drop size

2. Accurate positioning

3. Identical even drops

4. Precise positioning

All Epson printers have complete control over droplet formation. With piezoelectric printing technology, after the droplet leaves the nozzle, the ink is drawn inward to form an arc or "meniscus effect."

It is important that just the amount of ink that is needed comes out of the nozzle, and that excess ink is drawn back into the nozzle in such a way that satellite droplets do not appear on the surface of the liquid during vibrations - this is called meniscus control.

Meniscus control

Meniscus control in Epson devices ensures that there are no satellite droplets - unnecessary droplets coming out of the nozzle along with the main droplet.

Variable drop technology

Epson is continuously improving the Epson MicroPiezo printing technology.

But it is not only the smallest drop of print that is responsible for high quality prints. Epson products also use variable drop technology.

With this technology, 5 different ink drop sizes are now possible. This results in more accurate positioning of the drop.

Benefits for consumers:

Accurate color gradation and sharper detail at high print speeds.

Printer driver - flawless print management

To control printing and obtain the best print quality, Epson has developed a printer driver. The driver itself selects and controls the ink supply process depending on the type of paper and image. The printer driver has other functions as well. Epson PhotoEnhance technology automatically recognizes the image in a photo (portrait, landscape, etc.) and optimizes the brightness, color and contrast of the image as necessary.

Before you start printing, you set the type of image to print: draft, text, text with an image, or photograph. All other parameters are controlled by the printer driver, which sends the appropriate commands to the print head.

The benefit: You get great prints with no additional processing time.

Findings:

Epson MicroPiezo inkjet technology is the industry leader in printing.

Epson inkjet printers and MFPs provide:

PRINT QUALITY due to accurate color reproduction, transmission of halftones and shades, small details in photographs.

RELIABILITY due to the lack of heat and a stationary print head.

EFFICIENCYthrough the use of CISS and refillable cartridges.

With the combination of Epson MicroPiezo piezoelectric printhead, Epson software, high quality ink and Epson's best photo papers, you get superb print quality!

Not so long ago, a new series of printers and MFPs - Epson Expression Home XP appeared on the market and has already gained popularity.

And unsurprisingly, these are the junior models in the Epson printer line, which are sold at very affordable prices. In addition, Epson used a combination of black pigment and color water-soluble inks in these models. Pigment black ink provides good text quality on plain office paper. Color water-soluble ink allows you to print excellent quality photos on photo paper. You no longer need to find a compromise between the printing of abstracts and photographs. The result is a solid, versatile device, especially well suited for schoolchildren and students. However, with all its advantages, the cost of original cartridges is quite high. On average, about one and a half thousand rubles. But here the manufacturers of compatible consumables come to the rescue, which you can buy in the AdisPrint.ru online store. So how can you save money?

PPK - refillable cartridges

For those who do not print very much, refillable cartridges are suitable. Unlike original cartridges, they can be refilled with ink an unlimited number of times. Therefore, they are also called eternal cartridges. Each of these cartridges has an auto-reset chip that restores the readings of a full cartridge after refilling. As for the refueling procedure, it is elementary simple. You will need to open the rubber plug on the cartridge, pour ink into it with a regular medical syringe, and close the plug again. Let's count a little. For example, refillable cartridges Epson XP-103 and a set of South Korean ink InkTec will cost you a little more than a thousand rubles. Already savings. And if you also take into account the fact that you buy refillable cartridges once and for all, and a set of ink is enough for you for about 2000 photos, the savings become enormous.

CISS - continuous ink supply system

For those who print a lot, you can choose another option - CISS. It is a system of continuous supply of ink from large-volume donor containers, standing next to the printer, along a flexible cable to the block of cartridges installed inside the printer. Thus, filling ink into donor containers, you can forget about the need to refill the printer for a long time. In addition, since there is no need to remove the cartridges from the printer to refill, the possibility of air getting into the print head is eliminated. CISS cartridges, as well as PZK, are equipped with auto-resetable chips, and filling ink into donor containers is even easier. The only thing to consider when choosing a CISS is the presence of a small free space next to the printer for installing donor containers. The cost of CISS Epson XP-103 is slightly higher than the cost of refillable cartridges. Those. printing with CISS will be just as inexpensive.

Using compatible consumables, you will recoup your costs in just a few refills, including the cost of the printer itself.

Inkjet printer technologies Epson
page 1: features of Epson inkjet printers, MicroPiezo printing technology,
piezoelectric print head Epson MicroPiezo.

"Printing is not a spit"

Probably, there is not a single PC user who has not heard of Epson, the recognized world leader in the production of high-quality inkjet printers. Products of this company, as a rule, can always boast of high quality printing. But, isn't it, I wonder how it is achieved, this is the very quality? This is what we have to figure out.

Brand features of Epson printers

There is no doubt that Epson inkjet printers hold the technological leadership in terms of color printing capabilities among many models of modern devices of a similar purpose: in many test comparisons, the Epson brand occupies a leading position. And in combination with good reliability of printing mechanisms and reasonable price of devices, this allows the company every day to attract more and more users to the ranks of its admirers. Yes, Epson printers print just fine, and many people know about it firsthand. However, I am sure that very few have an idea of \u200b\u200bwhat technologies and how in this way such a bewitching beauty of the prints obtained on these devices is achieved. Let's try to find out more about this.

In the market of inkjet printers, the Epson models are primarily known as products that offer, in addition to excellent print quality, with high parameters of device reliability, also ease, ease of use. Also, one of the important advantages in the operation of inkjet printers of this company is the lower price of consumables for them - when compared with most models of other manufacturers of devices of this kind. This state of affairs, ultimately, is also due precisely to the peculiarities of the printing technology used by various companies in their products. After all, Epson is practically the only company on the market that remains an adherent of piezoelectric technology, which does not involve changing the print head together with the cartridge, which ultimately significantly affects the level of prices for consumables.

Perhaps many believe that the quality of a printer's prints is determined only by the resolution - if the device stuck more dots per inch, then the picture will turn out better, and the quality is higher. However, this approach is completely amateurish. In fact, in letterpress, like fashion, everything is not as simple as it seems to a layman. A number of scientific and technical achievements, a whole range of technologies developed by the company for use in its own products, are behind the excellent quality of prints obtained on Epson inkjet printers. And although each of these technologies solves some specific problem, they all ultimately constitute the components of one system aimed at achieving the main goal - to provide the best image quality for printing.

And what does this quality depend on?

Epson identifies the following main components that affect this indicator:

printing technology;

screening technology;

ink drop size;

resolution;

the number of colors in the cartridge;

quality of consumables.

Epson has developed a unique Perfect Picture Imaging System as a result of continuous engineering research and scientific development in the field of inkjet printing (to succeed in transferring electronic images to solid media, including the same paper). This system is the basis of a large complex of carefully technologically verified, well-developed optimal solutions. It includes four main basic components, which, however, are in close interaction with each other. And although all four components of the Perfect Picture Imaging System are constantly updated (and they are improved with almost every new line of printers), their basic set remains unchanged. Let's briefly describe them.

1. Epson MicroPiezo piezoelectric print head. The MicroPiezo printhead (Fig. 1) is the heart of the PerfectPicture Imaging System, in fact the basis of Epson's entire inkjet printing system.

2. Epson AcuPhoto Halftoning. AcuPhoto Halftoning is a technology that determines what color the final print will end up with. It optimizes the print results and allows for better halftones and color gradations.

3. Fast-drying Epson QuickDry Ink. Fast-drying QuickDry Ink, penetrating into the medium, dries instantly, thereby eliminating color mixing and maintaining a perfectly round shape of the applied dot. The unique ink chemistry delivers clear, vibrant colors with superb image sharpness comparable to that of a laser printer. This is true both for printing text documents and photorealistic images.

4. Genuine Epson media. The range of genuine Epson media (materials on which it is printed) is truly huge. Moreover, what is important, regardless of the format, size, shape and density, the use of original Epson consumables in the company's inkjet printers guarantees excellent photographic quality of the resulting prints. In fact, we are offered the widest choice of media for the implementation of any creative idea.

1. MicroPiezo printing technology

In modern inkjet printers, two main, but radically different printing methods are used: thermal inkjet and piezoelectric. The fundamental difference between both technologies lies in the method of forming ink drops, which will be applied to the surface of the carrier and, ultimately, form an image. This difference determines the difference in the printing mechanisms, and in many other things - up to the requirements for ink.

Thermal inkjet printing is used in printers HP, Canon, Lexmark. Technology Bubble jet (Injection Bubbles) was developed by Canon and used in their printers. HP printing devices are based on a printing technology called Drop-on-Demand... However, it has no significant differences from the Bubble Jet technology, using exactly the same operating principles.

The essence of thermal inkjet printing technology is that each of the nozzles of a thermal inkjet printhead is equipped with a heating element or, as they sometimes say, an ink evaporator. Under the influence of an electric current, the temperature of such a heating element reaches about 500 ° C in a few microseconds. With such a sharp heating near the thermoelement, the ink almost instantly boils, a kind of microexplosion, during which gas bubbles are formed. They grow in size and push the ink out of the print head nozzles (Fig. 2). And when the steam bubble collapses, it pulls the next portion of ink from the cartridge to the nozzle. Everything seems to be simple, convenient and practical.

But thermal jet technology has one drawback - it is very difficult to control the shape of an ink drop, since the process of its formation and ejection is difficult to control due to the explosive mechanism of the drop origin. But the irregular shape of the drop distorts the trajectory of movement originally set for it and, accordingly, negatively affects the accuracy of its positioning on paper. That entails a violation not only of the shape of the image point, but also of its location on the sheet. In this case, both text printing (text) and the quality of color rendering in color printouts suffer due to possible ink mixing. From the above, it is easy to conclude how important it is to have reliable control over the process of droplet formation when it leaves the print head nozzle.

We print inkjet

05/07/2009 10:30 Maxim Valov

Brand features of Epson printers

Is that inkjet printers Epson hold the technological leadership in color printing capabilities, there is no doubt - in many test comparisons, devices of this brand occupy a leading position. However, I'm sure very few have even a vague idea of \u200b\u200bhow such a bewitching beauty of the prints obtained on these devices is achieved. Let's take a look at this issue.

IN perhaps many believe that the quality of a printer's prints is determined only by the resolution - if the printer is able to "poke" more dots per inch, then the picture will turn out better, and the quality will be higher. However, this approach is completely amateurish. In fact, in the field of "letterpress" printing, everything is not as simple as it seems to a layman.

What does quality depend on?

Company specialists Epson the following main components are distinguished that affect the indicator of the quality level:

Printing technology,

Screening technology,

Ink drop size,

Resolution,

The number of colors in the cartridge,

The quality of consumables.

To combine all the components of the quality of the resulting image in a single printing device, the company Epson an imaging system was developed, which is, in fact, the basis for a large set of solutions. ABOUT it includes four basic components, which, however, are in close interaction with each other. And although all the components Perfect Picture Imaging System are constantly updated, their basic set remains unchanged. They can be briefly characterized as follows:

1. Piezoelectric print head Epson MicroPiezo (fig. 1) - main part PerfectPicture Imaging System, in fact the basis of the entire proprietary inkjet printing system Epson.

2. Epson AcuPhoto Halftoning - the technology that determines what color will eventually appear on the final print. It optimizes the print results and allows for better halftones and color gradations.

3. Fast drying Epson QuickDry Ink, which, penetrating inside the carrier, dry instantly, thereby eliminating color mixing and maintaining the perfectly round shape of the applied point. The chemistry of the ink delivers clear, vibrant colors with excellent image sharpness comparable to that of a laser printer, both for printing text documents and photorealistic images.

4. Epson original media (print media), the range of which is truly huge.

Printing technology

Thermal inkjet printing technology

In modern inkjet printers, two main, but radically different printing methods are used: thermojet and piezoelectric... The fundamental difference between both technologies lies in the method of forming ink drops applied to the surface of the carrier and, ultimately, forming an image.

The essence thermojet printing technology lies in the fact that each of the nozzles of the print head is equipped with a heating element or, as it is also called, an "ink evaporator". Under the influence of an electric current, the temperature of such a heating element reaches about 500 ° C in a few microseconds. with such a sharp heating near the thermoelement, an almost instantaneous boiling of the ink occurs, a kind of microexplosion, during which gas bubbles are formed. They grow in size and push the ink out of the print head nozzles (Fig. 2). And when the steam bubble collapses, it pulls the next portion of ink from the cartridge to the nozzle. Everything seems to be simple, convenient and practical.

However, thermal jet technology has one drawback - it is very difficult to control the shape of the ink drop, since the process of its formation and ejection due to the explosive mechanism of the drop origin is difficult to control. But the irregular shape of the drop distorts the trajectory of movement originally set for it and, accordingly, negatively affects the accuracy of its positioning on paper. That entails a violation not only of the shape of the image point, but also of its location on the sheet. At the same time, both text printing (the text is "blurred") and the quality of color rendering in color printouts suffer due to possible ink mixing.

In addition, for thermal inkjet printheads, when ink escapes from the nozzle, the main drop can be accompanied by a significant number of small satellite droplets caused by the impact of the same sharp ink boiling. These microparticles are expelled together with the main drop both at the moment of the "shot" and after the ejection of the main drop, forming as a result of excess pressure in the nozzle from unstable vibrations of the ink mass. And if the pressure created by vibrational processes exceeds the threshold of the surface tension forces of the ink at the edge of the nozzle, “unplanned” ink droplets will again break off from the nozzle (Fig. 3).

Satellite droplets are the main reason for the formation of "ink fog" along the contour of the main image. In addition, they cause random color mixing on the surface of the media, which can severely degrade color quality.

MicroPiezo printing technology

Unlike manufacturers using thermal inkjet printing method, Epson applies its unique printing technology Micropiezo (MicroPiezo), the main feature of which is the piezoelectric method of forming ink drops.

It is a common misconception that in a piezoelectric print head, the piezoelectric element itself acts on the ink when droplets are ejected. In fact, this is not the case. The piezoelectric element is functionally inextricably linked with a vibrating plate, which is called diaphragm, or meniscus... So it just affects the ink, pushing it out of the nozzles and then pulling it out of the cartridge.

P
under the influence of an electric pulse, the piezoelectric element is deformed, while changing the position of the diaphragm. The latter, in turn, increases or decreases the volume of the microcavity under it, thus advancing the ink along the capillary system of the print head. That is, the meniscus acts as a kind of piston, thanks to which the entire process of ink passage through the channels becomes controllable (Fig. 4).

Yes, the core of the technology Epson MicroPiezo - piezoelectric print head of the same name. But in fact, the mentioned technology includes three components that serve to optimize parameters such as print speed and maximum productivity, as well as allow you to achieve a wide range of print resolutions - from 720 to 5760 dpi. And these components - active meniscus control, micro-droplet printing technology and variable size drop printing.

Active meniscus control

The key point of this technology is the reverse movement of the meniscus, which is designed to ensure the reverse retraction of satellite droplets that form when the main droplet emerges (Fig. 5). By using active meniscus control, the following printing benefits are achieved:

The trajectory of the drop is not violated,

Provides extremely accurate positioning of the drop on the paper,

The correct spherical shape of the drop is guaranteed,

The correct shape of a point is formed on paper,

There is no "ink fog" in the image.

Meniscus control technology plays a key role in the precise positioning of ink drops on the media. AND this, in turn, determines such important characteristics as speed and, most importantly, print quality.

In addition, due to the use of an active meniscus control system (pull-in-ejection-pull of ink), the formation of random droplets-splashes that negatively affect the quality of the printed image is excluded. As a result of the reverse stroke of the diaphragm, the ink behind the detached "planned" drop is immediately drawn back into the nozzle of the print head, which does not even allow the formation of a cloud of satellite droplets, not to mention their sending to "free flight".

However, the ink supply method is far from the only factor influencing the parameters of the drop and, accordingly, the shape of the dot on the paper. The shape of the print head nozzles is also very important in droplet formation.

Influence of nozzle shape on droplet formation

The shape of the nozzles in the thermal print head is different from that of the micro piezoelectric head. For thermal inkjet printheads, nozzle shapes have ragged or uneven edges. This is not at all typical for piezo printing.

In addition to the shape, another important parameter of the nozzles that affects the print quality, and the state of the printing mechanism as a whole, is the size of the nozzle. The smaller it is, the greater the possibility of ink drying there, and the higher the likelihood of a printhead failure or deterioration in its performance (for example, light streaks may appear on printouts due to clogged nozzles).

ABOUT however, the standard way to reduce droplet size for thermal inkjet technology is to reduce the nozzle diameter. Its size in some models of printers reaches 4-5 microns. In Figure 6, you can see how the shape and size of the nozzle differs between the micropiezo print head and the products with the thermal inkjet printing principle. In these enlarged images, as they say, with the naked eye it is noticeable that the nozzle in the micropiezoelectric printhead is much larger (its diameter is 25 microns). But due to the fact that the process of droplet formation in the piezo head is controlled by the meniscus control technology, a droplet extracted from such a "large" nozzle can be smaller in size than droplets from narrower nozzles of the thermal heads.

In addition, temperature changes during the operation of the head and their relationship with the viscosity of the ink affect the correct application of ink drops.

Effect of temperature changes on printing

The viscosity of ink directly depends on its temperature and, naturally, affects the size of the resulting drops. The temperature rise caused by the work in the print head itself, as a result, lowers the viscosity of the ink, which leads to the formation of larger droplets. If the temperature of the head for some reason drops below the optimum, then everything happens exactly the opposite. ABOUT
cooling increases the viscosity of the ink and, accordingly, drops of a reduced size are formed (Fig. 7). Hence follows the practical need for constant control over the degree of ink viscosity in order to continuously ensure the standard droplet size and, not less important, stable operation of the nozzles. It is clear that for this it is necessary to somehow compensate for the negative consequences of changes in the temperature of the working environment.

Unlike thermal inkjet printing devices, there is no particularly significant heating in the micropiezo print head. However, immediately after switching on and after many hours of continuous operation, the temperature in the print head will differ significantly. To track these changes, the printhead Epson has a built-in temperature sensor that records the thermal state at certain times. And taking into account the specific temperature regime, the necessary amendments are made to the voltage supplied to the piezoelectric element (Fig. 8). By changing the force of impact on the diaphragm, ultimately, all deviations in operation caused by temperature changes are compensated.

However, do not forget that the print head of printers Epson calibrated based on the viscosity of the original manufacturer's ink. Therefore, in the case of using ink cartridges of unknown origin, the head may be incorrectly calibrated, and the size of the formed drops will be sub-optimal or even unstable. E if the viscosity is too high, it can distort the droplet path or even cause individual nozzles to fail. Which, quite naturally, will cause deterioration in the quality of the printed image. And in the worst case - and a malfunction of the print head.

Ink drop size

Grains of progress

The older generation of inkjet printers printed in droplets of the same size. At the same time, in order to ensure high speed of the devices, they used large ink drops, which made it possible to quickly fill the printed area. However, when using large drops, another problem arose: if in the dark areas individual dots on the printout were not visible, then in the light areas they became clearly distinguishable. Because to reproduce light areas, the printer simply began to put the same large dots less often.

The issue of invisibility of the raster (dot) structure of images obtained using inkjet printing technology is still an urgent problem. Improving our own piezo printing technology, Epson developed and implemented a number of technical innovations into its products, thanks to which the visible flaws of the raster structure on the printouts were practically eliminated. How was this achieved?

Drop by drop

Naturally, in order to make the dot structure of the printed image invisible, it is necessary to use small ink drops in the printing process, only a few picoliters in volume. It was to achieve this result that the technology was developed Ultra Micro Dots (printing with very small dots), when using which the printer starts printing in droplets of 1.5, 3 , 4 or 5 pl. (depending on the model of the device). This technology allows you to apply droplets of the lowest possible volume to reproduce light areas of the image, areas with very high detail, smooth color transitions, etc.

The smallest drop in printers Epson has a volume of 1.5 picoliters (pl). To get an idea of \u200b\u200bhow small this is, look at how it compares to a human hair (Fig. 9). Such tiny droplets are used when printing very light areas of the image: skin tones, highlights, folds of clothing, small details, etc. Naturally, when very small droplets are applied, we also get a raster on the carrier, but it is practically invisible to the human eye. For the diameter of the dots on paper is about 15 microns, while the boundary of perception of the human eye is about 40 microns.

Between speed and quality

Small drops are definitely good. However, if the image is reproduced only in drops of 3-4 pl, then it will be such a long process that it will be difficult to put up with it even despite the best result. What are the conclusions? Quite right, inkjet printing needs to find a reasonable compromise between the application of large and small drops. In search of this very compromise between speed and print quality, it was developed variable droplet size technology .

Changing drops

WITH yth technology of variable droplet size, also called Variable Sized Droplet Technology (VSDT), is to use larger drops to paint over solid areas and small ones to transfer halftones and color gradations. The advantages of the technology are undeniable - it allows you to form dots of different sizes in one pass of the print head (Fig. 10) and is able to optimize the printing speed. Optimal results are achieved by using an intelligent ink droplet system for different areas of the image: in a single pass, the print head uses both micro-droplets - to reproduce subtle color gradations - and larger droplets to fill dark and solid areas. As a result, with a minimum investment of time, a high-quality print is formed, close to a real photographic one.

The modern version of this technology allows printing with droplets of three sizes: medium and large droplets are applied to the darker areas of the image, characterized by low detail, and small droplets form bright areas. As a result, dark areas of the image are quickly filled with medium and large droplets. Thus, the printing speed of dark areas can be increased several times.

R let's consider how technologically it is possible to obtain drops of different sizes from the same nozzle of the print head. As already mentioned, how is printing done in the head MicroPiezo - the piezoelectric element is deformed under the influence of an electric current, the strength of which determines the intensity of the piezoelectric element operation, which determines the subsequent frequency of its oscillations. The oscillation frequency of the piezoelectric element, in turn, determines the size of the formed drop. From here it becomes clear how the droplet size in the head is controlled. MicroPiezo: By adjusting the current flowing to the piezoelectric element, you can control the droplet size. The current strength is higher, the oscillation frequency of the piezoelectric element is higher, the formed drop is higher. Even 2 single electrical impulses are used to obtain the largest droplets (Fig. 11).

Resolution

Permission to print

It is common knowledge that the print quality of an inkjet printer also depends on parameters such as resolution. Naturally, when developing new printing technologies Epson I just could not help but pay attention to the improvement of this parameter.

Back in 1998, the company introduced a line of printers with a resolution of 1440 dpi (dot per inch, that is, dots per inch). This move allowed her in those years to capture a significant share of the booming inkjet printer market. Recently, however, in all market segments without exception, users have begun to make more and more high demands on the quality of inkjets. ABOUT of course, professional graphics professionals are pretentious, however, home users have also significantly raised the level of their requests - they now need an inkjet printer not only for printing text and simple color documents.

Following the spirit of the times, printers Epson today got a resolution of 5760 dpi. A person who is not too versed in the nuances of inkjet technologies, especially at first glance, it is difficult to notice a tangible difference when printing a regular photo, for example, between 1440 dpi and 2880 dpi (Fig. 12). At the same time, an experienced user will immediately spot at least ten differences between printouts. Where will he see the benefits of the higher resolution image? First, such a high resolution allows for improved detail in both light and dark areas.

Anyone working with inkjet printers knows that in areas of smooth color transitions on a printout, so-called horizontal banding can sometimes be noticeable. Horizontal stripes appear along the path of the carriage carrying the printhead. And although this drawback in some cases may be associated with the low quality of the paper, nevertheless, such a defect is inherent in inkjet technology as a whole, and therefore it is quite difficult to avoid it completely. But when printing, for example, a face close-up on a sheet of A 4 this nuance becomes especially critical - the slightest manifestation of any regular structure on the printout immediately catches the eye. And only the ability to print with high resolution made it possible to almost completely eliminate this drawback, thanks to both a denser filling of the printable area and a more accurate positioning of dots on the paper.

The latter is made possible by the fact that high-resolution printers use a more precise control mechanism for the print head, which allows for better positioning during printing. As a result, the application of drops on the paper is more accurate, which, in turn, improves the transmission of fine details of the image and the quality of halftones. Technically, this is achieved by increasing the number of passes of the print head (Fig. 13).

Number of colors in a cartridge

Don't CMY "shy

Some time ago, at the dawn of the "printer industry", any color printer worked in the CMY color space, the base colors of which are Cyan (cyan), Magenta (magenta) and Yellow (yellow). All other colors and shades were obtained by mixing these three primary colors in different proportions. Purely theoretically, mixing these three types of ink should have produced an absolutely black color, but in practice this turned out to be unattainable - instead of black, a shade was obtained, which is more likely to be defined as "dirty brown". WITH With this in mind, black color (Black) was added to the CMY color scheme, as a result of which 4 primary colors appeared in the basic set of inkjet ink types (CMYK - Cyan, Magenta, Yellow, blacK).

But progress does not stand still - while inkjet printers were used primarily for printing documents, including color, four colors from the CMYK color scheme were quite enough (Fig. 14). However, as inkjets became more commonly used for printing high-quality color images and photographs, the problem of insufficient color gamut of prints became more serious. The point is that a four-color printer simply cannot reproduce the color range inherent in traditional chemical photography. The weakest point of the four-color technology is the transmission of halftones - the colors are too bright, flashy, and therefore unnatural.

More colors - nice and different

Thus, manufacturers of inkjet printers faced the need to expand the color gamut of the printer. It is with the aim of improving the naturalness of color reproduction by the company Epson and inkjet printers were released, the color cartridge of which differed in color scheme from the generally accepted one (we are talking about l frost of photo printers Stylus Photo). In these device models, two additional light colors, Light Magenta and Light Cyan, have been added to the three primary colors Cyan, Magenta and Yellow. Regular and light inks have different concentrations of the dye, and this also determines their different features when applied to paper (Fig. 15).

The benefits achieved by using the expanded color range include higher print quality in the light areas - there is no grain in the light areas. It also became possible to reproduce 4 times (!) More shades, which had the most positive effect on the overall quality of halftones, and made it possible to provide much smoother color transitions and gradations (Fig. 16).

But it's not just the "quantity" of ink that affects the quality of your prints. Much depends on the technologies used by the printer to form the final image.

Screening technology

Make it CMYK!

ABOUT original screening technology used in the company's printers Epson, is called AcuPhoto Halftoning... It is she who is responsible for accurately identifying and reproducing colors on the printout. Its use in printing makes it possible to convey more subtle color nuances and details. And thanks to the original proprietary color conversion tables from RGB to CMYK used, adequate color conversion is fast and accurate.

The process of preparing an image for printing begins with reading the pixels in the RGB system (in which the image is presented on a monitor screen and perceived by the human eye). Then the received data is sent to the corresponding 3D color conversion table ( 3D Look Up Tables), where they are translated into the CMYK system, "understandable" for printers (Fig. 17). Based on the data on the CMYK image, information about the formation of ink drops by the printer is prepared. In the process of rasterization by printers Epson random dot scattering technology is applied Error diffusion, used to redistribute CMYK data based on the distribution of color dots in adjacent areas of the image. At the end of the rasterization process, the CMYK data is transferred to the printer, where the print head is is animated by the formation and positioning of ink drops on the carrier, which then appear to our eyes as a copy of the original image.

A very important element in the formation of the final CMYK image is precisely the stage of working with the color matching table. Why? Yes, because if an error has crept in here, then after printing we will get a picture that is very “far” from the original.

Consent tables

What are they needed for? One of the most important processes in inkjet technology is recalculation of colors when changing from one color model to another. And a very important moment in this process is the degree to which the original color in the RGB image matches the color obtained in the CMYK image. This parameter is directly dependent on the color conversion algorithm used by the printer driver, and the conversion algorithm can vary significantly from printer to printer.

Inkjet printers use one of two technologies. The first is thermal jet: the dye is ejected onto the work surface under the influence of temperature. In the second, the dye is transferred to the surface under pressure, which occurs when the membrane vibrates. It is she who is called piezoelectric printing. Let's take a look at its features.

Depending on the method of supplying ink, the process can be continuous (constant supply of ink) and pulse (supply of drops is regulated, time intervals are set). In the first case, a high speed of drawing the image is achieved, in the second - the accuracy of the parameters.

Epson print head

The head of the printing mechanism consists of nozzles that are thinner than a human hair. It moves perpendicular to the substrate and leaves ink on it. This produces high-quality images with high detail and clarity.

The essence of technology

Piezoelectric inkjet printing gets its name from piezo crystals. The technology has been used since the 70s of the last century, although it was invented almost a hundred years earlier. Its discovery belongs to P. Curie and J. Curie.

Scientists described the essence of the piezoelectric effect as follows: on crystalline bodies under pressure there are electric charges opposite in sign. If you do not put pressure on these bodies, but stretch them, then the charges will change their sign to the opposite. As a positive charge changes to a negative one, the crystals change in size and act like a piston, squeezing paint out of the nozzles.

In practice, this means that an alternating current can be supplied to the piezoelectric elements, under the influence of which they will contract and expand, creating oscillations. To obtain the desired image, it is sufficient to change the electric field. The droplet volume varies and depends on the diameter of the print head nozzles, pressure, size of the ejection chamber.

High detail images allow you to print photos on special paper

Technology development by Epson

The principle of piezoelectric inkjet printing in printers is implemented and patented by Epson. She released equipment using this technique at the end of the twentieth century.

At the initial stage of the development of the method, crystal plates were embedded in the head of the device. Later they were replaced by plate piezoelectric transducers. Since 1994, all Epson Stylus devices have been equipped with such lamellas. The company has a monopoly on the production of such equipment. To do this, Epson representatives had to obtain several thousand patents in different countries.

Despite the fact that the piezo method is identified with the name Epson, the first devices of this type were created by Siemens in 1977. In them, the role of the transducer was played by piezotubes.

Epson Piezoelectric Inkjet Printer

Features of printing on inkjet printers

Plate-type piezoelectric transducers replaced tubular and flat ones. They are compact and provide high frequency dye spraying.

Modern printers are equipped with plate-type piezoelectric transducers that are sensitive to electrical impulses. When electrically charged, they flex and press against the meniscus of the ink tank. The reservoir pushes the ink onto the paper.

After that, the transducer is set in reverse motion and withdraws the meniscus. The reservoir increases in size, thereby creating thrust and refilling it with ink.

Printing on inkjet printers has the following features:

• Meniscus control. Thanks to active control and the absence of heating in the system, only the main drops are emitted from the nozzles, without the so-called "satellites". The image is sharp, with well-defined contours. Color rendering is improved.
• Adjustment of the volume of drops. Fewer droplets increase quality but lower productivity. By adjusting their size, it is possible to choose the optimal ratio between the duration of the process and the characteristics of the print.
• Application of paint with microdrops. This makes it possible to achieve the highest possible resolution, but the option is only available for devices that print with a resolution of 2880x1440 dpi.

The volume of microdroplets in Epson printers is 2 pl. This is the smallest indicator for inkjet equipment. In Lexmark printers, the droplet size reaches 3 pl, and in HP - 4 pl.

Another feature of piezoelectric inkjet printing is ink. They are free of additives and additives, as, for example, in inks for thermal ink devices. The compositions differ in electrical conductivity, degree of viscosity, they are not interchangeable.

Ink containers are included with the printer, but can be purchased separately

Advantages and Disadvantages of Piezo Printing

With piezoelectric technology, it is possible to take control of the entire inkjet process - from the choice of droplet volume and jet thickness, to the rate at which ink is ejected onto paper. This feature allows you to more accurately select settings for specific tasks, materials and printing formats.

Other benefits of piezo printing include:

• high quality, natural color reproduction - suitable for making photographs;
• system reliability - the head is installed directly on the printer, and not on a replaceable cartridge, due to which it lasts a long time;
• the ability to work with different images - the desired picture characteristics are achieved;
• energy efficiency - unlike dot matrix printers, no special effort is required to move the print head as it is lightweight.

However, the technology is not without its drawbacks. Sometimes, to get a good result, it is necessary for the print head to pass over the working surface several times. This increases cost and increases print time.

When changing cartridges, there is a risk of air entering the nozzles. They become clogged and print quality is noticeably reduced. To correct the situation, cleaning the mechanism is required.

Epson Stylus ink cartridges

There are special requirements for printed materials. Because the ink is thin enough, it may blur on loose paper and cause blurriness. Therefore, it is best to use high quality media such as coated paper.

Several years ago, Epson developed a new ink that can print on almost any paper. They are UV and moisture resistant.

Watch a video review of the Epson L800 piezoelectric inkjet printer:

Outcome

• Piezoelectric inkjet technology relies on the ability of piezo crystals to vibrate when exposed to an electric current.
• Thanks to the ability to adjust the droplet size, you can get high quality images with realistic color reproduction.
• The system is more reliable than other types of inkjet printing.
• The technology is patented by EPSON and cannot be used in printers from other manufacturers.