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Periphery. Piezo technology: drop on demand

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inkjet printing is a technology for producing an image using microscopic drops of ink sprayed by the printer's print head onto paper.

The technology of inkjet printing is similar to the technology of matrix printing, since in both the first and second cases the image is formed by dots. Only with matrix printing, the image is applied by hitting the needles on the ink ribbon, and with inkjet printing, by spraying ink onto the paper with the print head.

The most important part of an inkjet printer is printhead, which is an array consisting of many microscopic holes (nozzles, nozzles).

Close-up photo of an inkjet print head nozzle

At piezoelectric printing Above the nozzle of the print head is a piezocrystal, which bends under the influence of an electric current and pushes an ink drop out of the nozzle onto the paper. The stronger the current charge, the more the piezocrystal bends, and the larger the size of the extruded drop. By adjusting the charge of the electric current, you can control the size of the ink drops. Piezoelectric printing technology is used in Epson inkjet printers.

A schematic representation of the principle of operation of piezoelectric printers is presented below.

Working principle of piezo inkjet print head

At bubble inkjet printing the smallest thermoelements (microheaters, thin-film resistors) are placed in the nozzles of the print head, to which electrical impulses with a duration of 7-10 microseconds are applied. When heated, the thermoelements heat up the ink until ink-air bubbles form. Bubbles, increasing in volume, push ink drops out of the nozzle. After that, the heating stops and a new portion of ink is drawn into the nozzle. The fuser turns on and off at an incredible rate, ejecting approximately 24,000 ink drops per second from each print head nozzle.

Thermal inkjet printing similar in nature to bubble inkjet printers, with the only difference being that in bubble inkjet printers the heating elements are built into the nozzles of the printhead, while in thermal inkjet printers they are located directly behind the nozzles. Otherwise, thermal inkjet printing resembles bubble inkjet printing: the heating element heats the ink to the evaporation temperature. The ink boils, increases in volume, bubbles and is pushed out of the cavity of the nozzles onto the paper carrier.

A schematic representation of the principle of operation of thermal inkjet printers is shown in the following figure.

Working principle of thermal inkjet print head

Inkjet printers operate with microscopic ink droplets with a volume of about one picoliter. The diameter of the ink drop is about 13 microns. Approximately 10,000 such ink drops are placed in 1 mm3. Since the droplet diameter is larger than the print pitch, the droplets overlap when forming an image. Millions of ink droplets are involved in the formation of the image, so the image is very rich and high quality.

Drops of ink on paper

Color inkjet printing uses several different color cartridges. The number of such cartridges ranges from 4 to 8.

Inkjet printer with six individual color ink cartridges

Mixing color ink in various proportions allows you to get many shades. Inkjet printers provide more high quality color printing than laser printers. True, unlike laser printers, ink is consumed quite quickly when printing color images and photographs. In addition, inkjet printers print images more slowly than laser printers. But the cost of color inkjet printers is much lower than the cost of color laser printers.

Rapidly developing, inkjet printing is developing new segments and applications. In the fight for market prospects, R&D in printheads, inks and specialty formulations is crucial. A big plus when choosing an inkjet printing device will be basic knowledge about manufacturers and printhead technologies.

Any jet head works on the principle of electronically controlled spraying of liquid droplets onto the desired surface. The two main classes are continuous feed heads and piezoelectric pulsed (Drop on Demand, DOD) heads, each divided into subclasses.

In continuous inkjet printing, droplets are sprayed non-stop, falling either onto the media or into a container for recycling and reuse. In DOD equipment, the ejection of droplets depends on certain conditions, and they are formed using a pulse in the ink supply chamber. Varieties of inkjet DOD printers are determined by the characteristics of the pulse generation. There are three main categories of technologies on the market: thermal, piezo and continuous flow (electrostatic).

Thermal inkjet printing

The first thermal inkjet printing technology was proposed in 1977 by Canon design engineer Ichiro Endo. Thermal printheads have come a long way since the first desktop printers of this type were released.

Regardless of the design features, thermal printheads are united by a concept: small droplet size with high speed and density of nozzles.

In a compact ink chamber, droplets are formed by rapidly heating a resistive element. Rapidly heating up to several hundred degrees, it causes the ink molecules to evaporate. A bubble (pressure pulse) forms in the boiling liquid, which forces the ink out of the chamber. As a result, a drop appears at the other end of the nozzle. Once pushed out, the vacuum in the chamber is filled with fresh ink from the reservoir and the process is repeated.

The disadvantage of the technology is the limited range of compatible fluids: thermal inkjet inks must be designed for evaporation and resistance to high local temperatures. In addition, thermal printheads are adversely affected by the process of so-called cavitation: bubbles constantly form and burst on the surface of the heating element, from which it wears out. However, modern materials provide thermal inkjet heads with a fairly long service life.

To reduce droplet size and increase print speed, high-precision technologies are needed to increase the number of nozzles per surface width. Canon FINE printheads offer an impressive 2,560 nozzles per color (15,360 nozzles per printhead). Nozzles vary in diameter because thermal technology is not able to produce droplets of different sizes. In each head, nozzles of 1, 2 and 5 squares are combined in a special way.

Hewlett Packard has achieved impressive nozzle density in the Edgeline printhead. The design with a print width of 10.8 cm consists of five silicon chips arranged in a checkerboard pattern.

The physical resolution reaches 1200 dpi at an operating frequency of 48 kHz. The dual row of nozzles (10,560 per die) allows the Edgeline to apply two colors. When printing in one color, the second row remains as a backup. Each head, designed to work with water-based or latex ink, has 5 matrices - a total of 52,800 nozzles.

Edgeline is installed in latex printers and roll presses from HP. The 77 cm print width T300 comes with 70 printheads for each side of the printed web. Thus, in duplex mode, 7,392,000 nozzles function, and the machine applies 148 billion drops to the printed material every second with high accuracy. All thermal printheads are consumables and their life depends on the amount of ink passing through them.

Thermal printheads for desktop inkjet printers are also available from Kodak and Lexmark. Some of the models they completed have already been discontinued.

In the wide format water-based inkjet market, the battle is between Canon and HP, the only supplier of latex printers with thermal printheads. And no one but HP has yet offered a thermal printhead in a single pass configuration.

Thermal inkjet technologies are quite confident in their niche, but most large and extra large format roll and flatbed printers are now represented by models with piezo inkjet printheads.

Piezo technology: drop on demand

Piezoelectric printheads combine the principle of spraying drops. Thanks to a wide range of modifications for different materials and applications, they are very popular with inkjet printer manufacturers.

The principle of drop-on-demand technology is based on the change in the shape of certain crystals when voltage is applied. As a result, the chamber is deformed, generating an impulse. Piezoelectric inkjet heads from more than a dozen manufacturers are on the market.

Inkjet technologies have a lot of applications, printing is just one of them. Inkjet printheads are used for marking and coding, postal codes and addresses, document processing, textile printing and marking, engraving, photovoltaics, material deposition, and high-precision liquid dispersion.

Inkjet printheads can be classified by:

compatibility with liquids (compositions water, oil, solvent, UV, acid);
operating temperature;
number of nozzles;
physical permission;
print width;
construction material;
fixed or variable drop;
the smallest droplet size;
environmental friendliness.

The main difference between inkjet printheads is fixed or variable droplet size. Fixed drop printers are called binary printers. It is important to understand the differences between technologies and how they work.

Binary printheads produce droplets of a standard size. Sea options - from 1 pl to 200 pl or more (picoliter - one trillionth of a liter). The main advantage of the technology is that large drops cover the printed material faster. Another feature of printheads with a fixed drop size is reduced resolution. Therefore, they are better suited for large format printed matter, printing on textiles and other segments where resolution is not of paramount importance.

The smallest drop is provided by the Durst Rho P10 wide format printers: Quadro Array printheads with 10 pl offer up to 1000 dpi resolution. Inkjet heads with a drop size of 1 pl are not designed for graphics, but for the deposition of liquids and printed electronics.

Fixed drop printheads compare favorably with the spray rate, measured in kilohertz (1000 cycles per second). Inkjet printers based on this technology come in 4- and 6-color configurations. When working with large volumes, do not forget that the print speed of 4 colors is higher than that of 6 colors, and if several print heads are responsible for one color, the printer will generally “fly”.

Now there is an active debate on which technology is better and why - with a fixed or with a variable droplet size. But first of all, you need to take into account practical aspects: manufactured products, the cost of the printer, economically justified speed.

Variable drop size printheads are able to adjust the print resolution on the fly. To increase the drop, the system combines several drops of the base size.

Take for example a printer with a base drop of 6 pl. To get a drop of 12 pl, the system sends two pulses to the ink chamber at once: the drops meet in the air and merge into one. The drop sizes available for a particular printhead are called "levels".

The 8-level head forms drops of seven sizes. The piezoelectric head with support for 16 levels will give 15 droplet sizes. With a base drop size of 6 pl, the available options are obtained by simply multiplying the base drop: 6, 12, 18, 24, 30, 36, 42 pl.

If we analyze the frequency of spraying, it turns out that the formation of variable droplets takes more time, which is quite logical. For a 16-level piezo jet head, the base drop spray rate will be about 28 kHz. If you activate 8 droplet options for it, the spray rate will drop to 6.2 kHz. If all 16 options are involved, the speed is only 2.8 kHz. As you can see, when moving from the base level to the maximum possible 16 levels, the number of droplets formed is an order of magnitude less. Variable drop size printheads consistently print slower than fixed drop sizes. But they increase the resolution of small text and print quality in general.

To increase the performance of variable drop inkjet heads, printer makers increase the number of channels per color. The ink channel is a series of nozzles dedicated to a specific ink color - typical variant for scanning and printing in one run systems.

Scanning printing here refers to the method of inkjet printing, in which the carriage with the print head moves back and forth over the surface of the printed material, and it is fed in a start-stop mode. In some flatbed printers, the image is formed differently: the material reciprocates under a group of print heads that cover the entire width of the print.

Continuous Inkjet - High Speeds

Continuous inkjet technology is a non-contact version of high-speed printing that is used to print variable information onto moving material. Initially designed for adding dates, texts and barcodes, the modules now offer multi-color printing on roll materials. It's hard to believe, but Lord Kelvin was the first to patent this idea in 1867.

The principle of the technology is as follows: the pump delivers liquid ink from the tank to many tiny nozzles, forming a continuous stream of drops at a very high speed. The rate of droplet formation and spraying is controlled by a vibrating piezoelectric crystal. The speed of its vibration is called the frequency, which in this case varies from 50 to 175 kHz. Each nozzle delivers between 50,000 and 175,000 drops per second. They fly through an electrostatic field and, already charged, fall into a deflection field, which directs them to the material or to the collection tank for reuse. The bulk of the drops goes to processing, and only a small part forms an image on the print. One of the main advantages of this type of inkjet printheads is their high speed.

Kodak Stream is an example of continuous inkjet hybrid printing technology. Periodic pulses in the heating modules near each print head nozzle form tiny ink drops. By adjusting the size and shape of the pulse, the system changes the size of the dot and the speed of spraying drops. Stream technology generates droplets at 400 kHz, as fast as traditional web offset presses. Moreover, Kodak is sure that it is possible to increase the frequency of pulses.

The closest competitor to the Prosper CPM is HP's inkjet roll-to-roll CPM. The theoretical maximum frequency for it is declared at the level of 100 kHz. And for piezoelectric inkjet printers, the standard frequency is 25-40 kHz.

Stream technology is based on MEMS microelectromechanical systems (they were also used in HP Edgeline printheads). Modern production technology MEMS is similar in principle to the fabrication of integrated circuits, which are used to create subminiature inkjet structures on silicon. The nozzle plate is a mechanical element combined with electronics on a common silicon base.

choose any

Printheads are just one component of complex printing systems. To select technologies that are optimal for a particular company, be sure to take into account technological differences. Given the widest selection of offers on the market today, it is important to arm yourself with as much information as possible.

About the author: Jeff Burton ([email protected]), SGIA Analyst for digital printing and consultant for digital print production, color management and product mix, digital equipment and manufacturers. For more than 20 years in the industry, he has worked as a production manager, an association consultant, and a trainer. Author of numerous technical articles and speaker at industry events.

On the same subject:

We make a choice in favor of print quality and cost optimization

First of all, let's clarify some points. First, we will talk about the representative of the family announced last year Deskjet Ink Advantage, which differs from the earlier Photosmart and Deskjet families by significant savings in the cost of prints due to twice the yield of cartridges while maintaining their recommended price.

Secondly, cartridges for Deskjet Ink Advantage printers are no longer divided into standard and high-yield cartridges, but have the same capacity, comparable to the high-yield cartridges in previous families. But the starter cartridges (which come with the printer) still remain, they are marked with the word “setup”, and the amount of ink in them is clearly less. And for those consumers who use original cartridges, the manufacturer promises a reward - the opportunity to participate in promotions, receive gifts and discounts. True, at the time of testing, the awards were limited to an offer to download the HP Photo Creations program for free (which printer owners can already get) and three games, as well as purchase expendable materials at a discount from resellers who participate in the promotion. To put it bluntly: not the most inspiring list.

Finally, a little about terminology: Hewlett-Packard prefers to call "All-in-One printers" those models that, according to a more common classification, should be called MFPs - multifunctional devices designed not only for printing, but also for scanning, copying, and sometimes also for working as a fax. There are very few inkjet models intended only for printing in the range of HP products, as, in fact, from other manufacturers.

So, we have a printer Hewlett-Packard Deskjet Ink Advantage 5525 e-All-in-One.

Characteristics, appearance, equipment

We start with the characteristics declared by the manufacturer:

HP Deskjet Ink Advantage 5525 e-All-in-One Printer Key Features
Functions	Color: print, copy, scan
Print technology, number of colors	HP Thermal Inkjet
Dimensions (H×W×D), mm	146×436×325 (tray and lid closed, no cables) 414×436×575 (tray extended, cover open, cables connected)
Weight (net/gross), kg	5,1/6,5
Power supply	Max. 14.64 W, 100-240 V AC, 50/60 Hz
Screen	6.74 cm, touch color LCD
Standard Ports	USB 2.0 (Type B) WiFi 802.11b/g/n
Print resolution	Colour: up to 4800×2200 dpi B/W: up to 1200×600 dpi
Scan Resolution	up to 1200 dpi, 24 bit
Print speed, ISO	Colour: up to 8 ppm B/W: up to 11 ppm
Memory	64 MB
Memory card compatibility	Memory Stick Duo Secure Digital/MultimediaCard
Supported operating systems	Microsoft Windows, Apple MacOS
Monthly load: Maximum Recommended	1000 A4 pages 300–400 A4 pages
Printer control languages	HP PCL 3 GUI
Cartridges	Black HP655 (CZ109AE), up to 550 pages Cyan HP655 (CZ110AE), up to 600 pages Magenta HP655 (CZ111AE), up to 600 pages Yellow HP655 (CZ112AE), up to 600 pages
Guarantee period	12 months
HP Deskjet Ink Advantage 5525 full specifications

As you can see, the printer itself is light and compact, packaged in a small and well-designed box. When installing, you just need to provide enough space above the printer so that you can open the scanner cover. I must say that you have to get used to this cover: the scanner itself is a printer cover, which must be thrown back, for example, when changing cartridges or removing jammed paper. At first, one would like to fold the entire scanner to put the original on the glass: the presence of its own cover does not stand out visually.

The printer can be placed in a niche with a height of 34-35 cm - this is enough for access to the inside and for working with the scanner, although it will not work to fully open the scanner cover.

Unfortunately, the scanner lid is not fixed in a fully open state and can slam shut at the slightest push. We note in passing: the hinges of the scanner lid are the most common, they do not rise when a thick original (book, magazine) is placed on the glass.

Access to the back of the printer is only needed to connect cables. To remove jammed paper, simply open the printer cover and remove the handle cover.

The output and input trays are located at the front, at the bottom of the printer. The feeding tray is retractable, has a hinged lid; it holds up to 80 sheets of plain paper, up to 30 sheets of photo paper, up to 5 envelopes, or up to 40 sheets of film. To stack paper, it is not necessary to pull out the tray (fully or partially), you can put in a stack of sheets without it, it is only important to advance the paper until it stops, otherwise there will be feeding problems. There are no difficulties here: after one or two attempts, the user gets used to stacking the paper correctly, but getting used to paying attention to the position of the side limiting plates every time is more difficult, and sometimes the paper starts to feed with some skew.

The output tray can hardly be called an independent design: it's just a plastic bracket that slides out of the input tray, it can hold up to 15 sheets of plain paper or up to 10 sheets of photo paper. When working with this tray, one should not forget about accuracy: it does not look very durable. Again, its capacity is too small - according to our observations during testing, more than 20 sheets of plain paper in it are already poorly held, they can crumble. And with the declared maximum number of copies per cycle (up to 50), the capacity of the receiving tray does not fit in any way. In general, when printing or copying large volumes, you will have to constantly monitor so that the prints do not crumble.

The 5525 does not have an automatic document feeder, but it does have an automatic document feeder. duplex printing(duplex, duplex).

The appearance of the printer is quite modest, most of the surfaces are matte, but not without gloss: there is a fairly wide shiny strip in the front, from which the control panel protrudes, also glossy.

The control panel is similar to a large smartphone, tilted at the front of the printer. It highlights a round on-off button (with white backlight) - the only mechanical control, all other buttons are touch-sensitive (either on the color LCD screen or around it) and are activated depending on the operating mode.

The touch screen with a diagonal of 6.74 cm has a good sensitivity and sufficient brightness (it has three levels of adjustment). But there are problems with contrast, and they are connected not so much with the screen itself, but with the angle of the panel: the contrast is quite sufficient if you look at the screen normal to its surface, but this is possible for a person sitting next to a printer installed on the table. If a person does not sit, but stands at a convenient distance for work, then the image on the screen is less visible, and you either need to move away from the printer or bend down. Well, reflections from the glossy surface of the panel will interfere in any case. In addition, touching the screen does not pass without a trace: it is quickly covered with fingerprints and takes on a not very presentable appearance.

The memory card slot is hidden behind an inconspicuous cover to the left of the paper tray. It is possible to connect SD / MMC cards and Memory Stick Duo, but work with USB flash drives is not provided.

Includes 1.7m power cable, software CD, descriptions, and four starter cartridges. The USB interface cable must be purchased separately.

Cartridges have the common name HP 655, we will give the manufacturer's indexes by color:

CZ109AE Black
CZ110AE Cyan
CZ111AE Purple (Magenta)
CZ112AE Yellow

The average yield of a black cartridge is 550 pages, color - 600 pages. They are designed for installation in the 3525, 4615, 4625, 5525, and 6525 printers in the HP Deskjet Ink Advantage family. Each cartridge is only a container with ink and a control chip, so the price of the cartridge is low.

Preparation for work

We got the "Press Test Unit" - a sample for the press, in which the fixing shipping tapes have already been removed, the cartridges have been installed, and even about 80 sheets have been printed.

However, the initial installation procedure should not cause difficulties: all shipping tapes are visible from the outside, and it is impossible to forget to remove any; the procedure for installing cartridges is presented in animated help - however, to access the help, you first need to install software from the attached disk, but you can simply download in Russian from the manufacturer's website. In addition, there is a hint on the packaging of the cartridges.

Now we need to get used to the control panel a little. Its full functions are described in the manual, so let's just say a few words.

For work, you can choose one of several languages, including Russian. Russification as a whole is quite normal, only in some places there are Latin inscriptions like “Apps”.

There are five main modes displayed by icons on the LCD indicator: copying, working with photos, scanning, as well as working with applications (those same “Apps”) and templates; Naturally, each of the modes has parameters.

On the “home page” of the screen, there is also a separate row of four buttons, two of which enter the wireless control menu, the third displays information about the approximate ink level, and with the fourth one you can get to the printer settings menu.

Navigation is assisted by four touch buttons located to the left and right of the screen, they are activated and highlighted depending on the situation. Two more familiarity on the side of the screen are occupied by buttons for calling help (of course, not comprehensive) and canceling the current operation. Finally, above the power button, there are two touch buttons with their own LED indicators, designed to call up the wireless and ePrint control menu.

Offline work

Without connecting to a computer or establishing a connection with a mobile device, you can only configure basic settings, perform some maintenance functions, copy, work with memory cards and applications.

The first on the “home page” of the menu is the “Photos” icon, which allows you to copy already printed photos from the scanner glass, as well as work with images on memory cards. When a card is inserted into the slot, the printer searches its contents for JPEG, TIFF and PNG-24 files (not only in the root directory, but also in folders), and then displays the found images on the screen as a gallery. If you wait a bit, the photos will be shown one by one in slide show mode.

Each photo can be viewed separately, edited - rotated, resized, cropped, etc. (naturally, the capabilities of a printer cannot replace a graphic editor), determine the layout (for example, paper 10 × 15), and then print in the required number of copies.

From the available photo in in electronic format you can take a photo for a passport or other document: the required size of the future photo is set (for example, 25 × 36 mm), the size of the photo paper to be printed on, then the image from the file is cropped, after which the printer will reduce it to the specified size, place it on layout in the maximum possible quantity and print.

If you need to copy "paper" photos, they are first scanned, and then processed in the same way as files from a memory card, and printed. Naturally, the participation of a memory card is not required for this.

The "Copy" icon allows you to copy documents, including those containing illustrations, in black and white (more precisely, in grayscale) or color modes. You can set the copy quality, make the copy lighter and darker, shift the edges, etc., for which you need to delve into the menu, but the main parameters - the number of copies, quality (set through the menu or draft), color or black and white - are set in the first window of the copy mode. You can also set whether to copy a two-sided original or two one-sided to a two-sided copy.

Clicking on the "Scanner" icon will prompt you for a way to save the scanned image: to e-mail, to a computer, or to a memory card. We will deal with the first two methods later, but for now, let's say a few words about saving the scan to the card, especially since most of the steps for all three methods will be the same. So, first of all, we will be asked to touch the screen to preview the future scan. If the original size is smaller than A4, then the size is automatically determined and a borderless image is displayed on the screen, which will be scanned. At this stage, we can set the save format (JPEG or PDF), as well as the resolution - 200, 300 or 600 dpi. After that, you can start scanning.

Files are saved in the automatically created DCIM folder, which forms subfolders with a limit on the number of files saved in each of them (similar to what happens in digital cameras). File names are in the ScanXXXX.jpg(pdf) format, where XXXX is an automatically incremented number. The time spent and the sizes of the received files are given in the "Testing" section.

As it was said, working with applications (“Apps” icon) is possible only when connected to the Internet via wifi network, but the pre-installed set of templates can be used immediately by clicking on the "Templates" icon. Six sets of templates are available - calendars, lists, games, notebooks, graph paper and music paper, each of which has from 2 to 4 options, and the inscriptions on the templates (if any) are Russified. Some of them are presented on scans. Of course, every owner and every day will not need such printouts, but something may be useful.

If the network to which the printer is connected has Internet access, then Apps become available. At the time of testing, a set of templates was available (actually the same as discussed above, with only minor additions), as well as a rich set of pictures with characters from popular DreamWorks cartoons - coloring books, puzzles, games for preschool and younger children school age, which you can print and offer to future users of Hewlett-Packard products. In addition, there is hope that the sets of both templates and pictures will be replenished. The printing process itself is very simple: select a category and images in it, set the desired number and wait for the images to be downloaded from the Internet and printed. Examples can be seen in the scans.

Connecting to a USB port and working with a computer

The connection does not begin with connecting the printer and computer with a cable, but with installing drivers and software.

The choice of installed applications is offered:

research to improve HP products,
HP Deskjet 5520 series Help,
Microsoft Bing Bar,
HP Update program to update installed software,
HP Photo Creations editor (the bundled disc contains only the installer of this program, which needs Internet access to download the program itself).

If you select a USB connection, a warning appears that some services are not available for the printer. And only then does a proposal appear to connect the printer and computer with a cable.

At the end of the installation of drivers and software, you need to select several options for interacting with the printer - a way to display warnings about the remaining ink, auto-off time when idle, and even "bind" cartridges to the printer so that adversaries cannot steal them and put them in another similar printer (as far as it is it is necessary and important, we do not undertake to judge), and the cartridges themselves could not be refilled and used in another printer (this is very important, but not for the user, but for the manufacturer).

This is followed by a call for savings - on paper (print on both sides and use recycled paper!) and on electricity with the technologies offered by the manufacturer. The process ends with the appearance of the "HP Printer Assistant" window, where you can view and change printer settings, perform maintenance operations and initiate a scan.

You can also check the ink level:

Please note: in this screenshot, the blue cartridge is simply “655” - it is from a separate delivery, and the rest came with the printer and are marked “655 setup”.

I must say that not everything is going smoothly with the assessment of the ink level: even when the ink in one of the cartridges was clearly over (filling with this color disappeared on the test sheets), the “HP printer assistant” and the corresponding menu item of the printer itself showed approximately equal, albeit minimal , level for all cartridges. Messages about the low ink level (“Low ink”) had previously appeared both on the printer indicator and on the computer, but somehow unobtrusively, and after the apparent end of ink, both the printer and the computer did not give any alarms ...

We tried to set both "show ink warnings immediately" and "only when printing", but the printer continued to print in the remaining colors without warning.

It's hard to say: the absence of a hard stop at the end of ink in one of the cartridges is a blessing or a disadvantage. One thing is certain: the owner has no doubt that the ink has been used to the last drop.

The cyan cartridge is nearly depleted.

The settings provided by the driver are quite familiar to anyone who has already dealt with Hewlett-Packard products.

There is not much to tell about the print function, so let's say a few words about scanning. Two drivers are installed: TWAIN and WIA. The WIA interface is standard, the set of settings in it is not rich:

The TWAIN driver in this case also does not indulge in a wide range of settings, but you can create a set of presets for frequently used scanning tasks in it. The TWAIN driver is enabled, for example, if you use the "HP Printer Assistant" scanning function.

You can also initiate scanning to a computer from the printer panel, you just need to select a computer as the destination and set the one connected via USB. True, unlike scanning to a memory card, here you can only choose the save format - JPG or PDF, but for some reason you cannot set the resolution: only 200 dpi. The scanned image will appear in the My Documents folder, the name setting method is the same as when scanning to a memory card.

Wi-Fi connection

First of all, you need to dock the printer with an existing router on the network, for which you need to press either the button with a touch screen wrench on the control panel of the printer, or a separate button for managing wireless connections, and then select either "Wizard wireless network', or 'Settings'. After that, you can get a list of available networks, select the one you need and enter a password, but it's easier to use the WPS (Wi-Fi Protected Setup) function - first press the WPS button on the router, and then start the wizard on the printer. The process takes a few seconds, after which the blue Wi-Fi mode LED, which was blinking before, turns solid, and the owner can print a report and go to work on the network.

By default, the printer obtains an IP address automatically via DHCP, but it is better to set a static address or reserve an address for it in DHCP.

Then you need to install the printer driver on your computer, which will require the supplied CD. The procedure is the same as for a local connection.

The printer has its own Russified web-interface, which can be used to check the status, settings, maintenance, and also for scanning. To get to the web interface, just type the printer's IP address in the address bar of the browser, and the address itself can be found by pressing the wireless control button on the printer panel.

Web scanning is disabled by default, to enable it, go to the "Settings" tab, then "Security", "Administrator options", where you enable this feature. Information about this appears when you go to the "Scanning" tab, but there is a slightly different path to the right place - apparently, the inconsistency arose during Russification. When enabling the webscan feature, there is a note stating that the printer must be turned off and on again for the settings to take effect; we did not have to do this - scanning became available immediately.

Clicking "Start Scan" will display the scanned image in the viewer window, and clicking on this window will save the file to your computer. There are two formats: JPEG and PNG, you can set the resolution and color preferences, set the compression ratio and adjust the brightness (all changes become visible in the viewing window only after clicking "Start Scan").

The only thing that cannot be set is the scan area, you can only set the paper size.

But you can also scan from the "HP Printer Assistant", as well as from any graphics program that supports the Acquire function through the WIA and TWAIN drivers, as was done with a local connection. Through the "assistant" and when connected via Wi-Fi, printer information, settings and maintenance are available, and new items appear in its interface - switching to the printer's web interface and scanning control.

Scan to email

Of course, this feature, as well as the ePrint function, is available when connected via Wi-Fi to a network with Internet access.

Scan to e-mail from the printer's control panel requires the recipient's address to be specified: an input line is displayed, which must first be tapped with a finger to bring up the keyboard. Then a 4-digit PIN code is sent to the specified address (the address of the sender [email protected] , the address will be the same for all scanned and sent images), which must be entered into the printer. After that, the recipient's address can be used for automatic login if there is one recipient of e-mail scans, or it can be saved in the address list if there are several such users. If the user forgets the PIN code, he can get a new one.

When scanning to e-mail, you need to choose what exactly is scanned: a photo (a JPEG file will be sent, you will need to set the sheet format from 4 × 6 inches to A4) or a document (PDF format, no additional settings are provided). After the scanning phase, a message appears indicating its completion, but it is not necessary to press the OK button: sending will automatically begin. The sending stage, depending on the network and Internet channel load, can be quite long, up to several minutes, but the printer can be used for other tasks at this time.

ePrint

This feature is for printing jobs sent from mobile devices and any computers other than local network but also from anywhere in the world. It does not require installation of additional software.

First you need to activate this function on the printer - for example, by pressing the ePrint button; the end result will be getting the address Email for this printer with a "cheat sheet" printout. The address format is quite difficult to remember: we got a combination of 13 letters and numbers, to which we need to add @hpeprint.com.

Now you can use the ePrint function, for which it is enough to attach the files to be printed into an email message and send it to the printer's email address. Photos and other images in BMP, GIF, JPG, PNG, and TIFF formats, Microsoft Word, Excel, and PowerPoint files, HTML, PDF, and TXT text files are supported. Of course, there are file size limits - the entire email message and each attachment cannot exceed 5 megabytes, and the total number of attachments cannot exceed ten, otherwise they will not be printed. There are some other terms of use that can be found on the Hewlett-Packard website.

If the printer is turned off or not connected to the network when the print job is sent, the job will be stored on the ePrint server for 24 hours, but you must have account on eprintcenter.com (or hpeprint.com - it still redirects to the desired page), after entering which you can view the history of jobs and print those that were not printed.

The registration procedure is very simple, you just need to specify the email addresses - your own and the printer, as well as set (and remember) a password. Among other things, you can create a list of senders who are allowed to use the printer for ePrint printing.

However, the choice of print options is very limited. So, jobs are always printed with a resolution of 300 dpi, and the paper size can only be selected from A4, Letter and Legal (naturally, this choice does not affect the actual size of the paper that is placed in the printer's input tray). Actually, the only option available for adjustment is the choice of color or monochrome printing for all jobs.

But you can change the printer's email address to a more intelligible one that can be easily remembered. In addition, the owner can register several printers for his account with the possibility of deleting later, as well as add applications from the list to each of the printers. The account itself can be deleted if there is no need for its further use.

Tests

For testing, we use our own methodology, available for repetition, and the results we receive may not match those indicated on the official sites. The previously used, revised and supplemented was adopted as a basis.

Reaching readiness after switching on: from 26–28 to 47–48 sec; measured from pressing the power button to the end of various processes, accompanied by manipulations with the print heads and the corresponding sounds. Such a gap in time is explained by differences in the procedure for initializing the printer after a long shutdown (the time to reach readiness is longer) and after turning it off for short term(time less).

Print speed

The values were obtained for the USB connection of the printer to the computer, when both the printer and the computer are connected via Wi-Fi (in Infrastructure mode, 802.11n; there are no other devices on the test network), the print time for a wide variety of test files is almost the same.

PDF file, monochrome printing of 11 A4 sheets with text information, countdown from the first sheet output:

PDF file, print 20 sheets of text with graphic design and illustrations in color:

The values obtained by us are in good agreement with the declared speed for monochrome printing (up to 11 ppm) not only in draft, but also in normal print quality, however, for color documents, the print speed is close to the declared one (up to 8 ppm) only in draft quality . However, we recall that the manufacturer used the ISO method for measurements, and we use our own, more accessible for repetition, since a consumer who decides to check the characteristics declared by the manufacturer will almost certainly not be able to do this - if only because he cannot find test sheets in the public domain ISO/IEC standard.

30-page DOC file (monochrome print, normal quality, default margins, text in Times New Roman 10 pt, headings 12 pt, from MS Word):

*) duplex printing should be assigned in the printer properties (i.e., by means of the driver), and not in the MS Word print dialog.

For 2-sided printing, after the first side of the paper is printed, there is a pause of a few seconds to dry the ink. Double-sided printing speed is, of course, reduced, but not as much as in some other printers.

A4 Color Photo Print Time:

You can set borderless printing, then the image will take full sheet, otherwise the minimum margins will be about 4 mm.

In addition, the ability to select print quality depends on the paper type set - for example, if you try to set "Maximum dpi" for "HP Everyday Photo Paper Matte" media, a setting conflict message will appear asking you to fix it automatically or manually. Print quality options that are not available for the given paper type (or vice versa: paper types that are not available for the given quality) are marked with a yellow triangle with an exclamation point.

Unfortunately, the list of paper types in the driver is far from exhaustive even for paper products bearing the Hewlett-Packard brand; besides, it is sometimes difficult to compare the English name of the paper with its types listed in the Russified driver. So, we were provided with paper "HP Everyday Photo Paper, semi-glossy" (i.e., everyday photo paper, semi-glossy), while the driver version 8.79.00.1124 offered only "HP Everyday Photo Paper, matte"; and for "HP Premium Plus Photo Paper, high-gloss" I had to select "HP Premium Photo Paper".

When printing on transparencies, the driver's menu offers a single option: Transparency, for which only regular quality printing with borders is available - other quality options, as well as borderless printing, cannot be set.

When printing multi-page documents, the printer periodically makes short pauses, for a second and a half.

Copy speed

Copy time for one A4 sheet at different quality settings (scale 1:1, plain paper):

*) without taking into account the scanning stage, after which three confirmations are required - size and layout.

If N copies are made from one original, then the total time is less than "×N" because scanning is done only once (the more N, the shorter the time per copy).

Maximum copy speed of A4 monochrome text original at 1:1 scale (calculated from 50 pages; plain paper, draft quality); to show the dependence of speed on the degree of filling the area of the original with an image during inkjet printing, one more measurement is made - copying a blank sheet.

During testing, we printed about 400 sheets, and the prints did not appear distorted, requiring head cleaning.

Scan speed

Scan of A4 test strip in color - offline, to SD card (time/file size indicated):

Format	Permission
Format	200dpi	300dpi	600dpi
JPEG	25 sec / 349 KB	28 sec / 1.78 MB	1:54 min / 6.16 MB
PDF	17 sec / 338 KB	24 sec / 1.78 MB	1:29 min / 6.15 MB

Since scanning from the printer panel to a computer is only done at 200 dpi and in color, scanning from a computer was done with the same settings:

Feed path test

Evaluates the performance of the feed path when using different media. A significant amount of media is being loaded different kind, sets the printing of numbered pages and counts the number of any kind of problems: misfeeds, jams, multi-media pickups.

A run of 200 sheets (more precisely, 80 + 80 + 40 - as much as the input tray allows) of A4 80 g / m² paper, 25 envelopes and 25 sheets of film did not reveal any misfeeds or jams.

The printer works fine with even 280 g/m² photo paper even though the paper has a 180 degree bend in the paper path.

For a practically new printer, the absence of feed problems is not a plus - it should not be otherwise, but a different result would be a reason to think.

Print quality

Below we give an assessment of the results with a minimum number of illustrations, but you can also get acquainted with the full scans of the obtained samples.

There are no complaints about both printing and copying texts when setting both the best and normal quality. Text documents on plain paper remain legible up to 4 pts even at draft quality; prints with the best and normal quality are difficult to distinguish, in draft quality the main claim is to fill, which turns out to be noticeably paler (which, in fact, is quite understandable), and when copying in draft mode, small details are lost, the contours of the letters become more torn, however, the text in in general, it retains readability.

When printing a color test strip, the printer gives very good color reproduction, registration and detail. The black color is dense, on a percentage scale it is distinguishable from 1-2 to 99-100%. Wavy and slanted colored lines are smooth, without jerks and steps. The quality of the photo printing is also excellent. However, much here depends on the choice of paper: what has been said largely applies to printing on photo paper (for example, for printing photos we used high-quality HP Premium Plus Photo paper provided by the manufacturer), but if you work with ordinary office paper, even class A, then it is impossible to achieve the best results - remember what was said above about the dependence between the print quality options available in the driver and the choice of paper type. You can, of course, “deceive” the printer by setting a different paper in the settings than what is actually used, but this number will not work without compromising the quality of the prints.

We were also pleased with the quality of photo copying: it is difficult to distinguish between the original and the copy.

When working with photographs, the lack of a paper feed system was confirmed: you need to carefully monitor the position of the limiters in the tray, otherwise the sheets begin to feed skewed, although not very significant, but quite noticeable during borderless printing.

Prices

At the time of publication of the review, the average price for the considered printer in the Moscow region was about 4350 rubles, and HP 655 cartridges, which fit various Deskjet Ink Advantage family printers, were offered at an average price of around 300-350 rubles.

findings

I must say that in this price segment of inkjet multifunctional printers is quite crowded: different manufacturers offer many models with approximately equal consumer properties and a similar balance of advantages and disadvantages. Therefore, the savings on cartridges announced by Hewlett-Packard for the Deskjet Ink Advantage family can be a determining factor when choosing: indeed, many similar printers have the same price for cartridges, but the declared number of prints they provide is noticeably less.

Another argument in favor of the HP Deskjet Ink Advantage 5525 is the high quality of color printing, especially photos.

And the equipment of the printer is unlikely to leave much to be desired: built-in duplex with a good duplex printing speed, two interfaces - USB and Wi-Fi, the ability to work with memory cards. Of course, you can complain about the lack of an automatic document feeder and a port for USB flash drives, and someone may lack an Ethernet connection, but such additions, of course, would significantly increase the price of the product.

The not-too-pleasant features of the input and output trays, as well as the scanner lid, should be attributed not only to savings, but also to the desire to make the multifunction printer as compact as possible.

But the lack of a USB cable, traditional for many Hewlett-Packard printers, should be attributed to disadvantages: this has little effect on the final price, but adds trouble to those owners who decide (today or later) to use a wired connection to a computer.

The manufacturer positions this model primarily as a device for home use. Of course, high-quality photo printing (including on photo paper with a very high density, up to 300 g / m²) and comparative cost-effectiveness are very important for private owners, however, in offices, such features, combined with versatility and the ability to wireless connection will not go unclaimed.

Thanks to Hewlett-Packard for providing the printer

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 in certain time. Unlike systems continuous action, there is no constant pressure in the volume of ink, and if it is necessary to create a drop, 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. electric field, which makes it possible to quite accurately vary the volumes of the resulting drops, and therefore to a sufficient extent affects the size of the resulting spots on paper. However, practical use It is difficult to modulate the volume of drops because not only the volume, but also the velocity of the drop changes, which, when the head moves, causes errors in point positioning.
On the other hand, the production of print heads for piezoelectric technology turns out to be too expensive per head, so in Epson printers the print head is part of the printer and can cost up to 70% of the total cost of the entire printer. The failure of such a head requires serious after-sales 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 cartridges high resolution, and the junior and medium models of the Zx3 family, the 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 this composition ink and the printhead with which it will be used. Indeed, on the one hand, the higher the viscosity, the worse the ink spreads over the surface of the paper, giving a smaller dot size and the clearer the image will be. On the other hand, too 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 print head.
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 an image depends on the chemical composition of ink and paper, and the architecture of the printer.
Mandatory requirement the ink has 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 the so-called color tables, which are used to convert the color space in which the original image was created into some “deformed” color space that takes into account the peculiarities of 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 detection that produces good image quality with no setup required. Auto mode also allows you to achieve the optimal combination of quality and speed of printing a document. 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. characteristic feature drivers of this series 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.

Among all imaging technologies, inkjet printing has gained its popularity.

It is used in printers, including large format ones.

The advantage of this technology is that the drop of ink is formed only at the right moment, which allows you to get high-quality images.

What is thermal inkjet printing

In this article, we will tell you what thermal inkjet printing is, its advantages, the principle of operation, and in what cases it is used.

The finished image consists of a large number of microscopic ink dots of various colors (color inkjet thermal printing).

At the moment when you need to apply the image, there is ink in the microscopic chamber of the nozzle, which must somehow be pushed onto the surface of the printed material (for example, paper).

The thermal method of printing consists in the fact that there is a heating element in the chamber, to which current is supplied at the moment of printing. The duration of a momentary switching on of the current is a short period, up to 2 millionths of a second.

Under its action, the element heats up, the temperature of the paint increases to 500º, the volume of paint in the nozzle increases, which increases the pressure in the chamber, and a portion of the dye is pushed out of it. There is information that in the chamber, at the moment of heating, a pressure of more than 100 atmospheres is formed, which is quite a lot.

After that, a vacuum is formed, which contributes to the retraction of a new portion of paint. This process is repeated several thousand times per second.

Thermal Inkjet Equipment

This method of printing is used in the vast majority of inkjet printers. The technology was introduced to the market in the early 1980s. The leading manufacturers are Canon, HP, Lexmark.

Modern equipment makes it possible to form drops up to 35-40 microns in size, which makes it possible to obtain a high-quality and detailed image.

Typically, thermal printers have two printheads. One is for black ink printing and the other is for color printing (cyan, magenta, and yellow).

There can be up to several hundred nozzles in one printhead, depending on the model.

Depending on the model, the heads can be inseparably connected to cartridges or built into the printer, that is, reusable. The latter option makes it possible to be more confident in the quality of printing, because this element does not have time to work out its resource. But in this way the price of printing becomes more.

Advantages and disadvantages of thermal printing

Thermal inkjet printing is widely used in printing technology, thanks to:

quiet operation of the equipment,
ensures high quality and resolution of printing,
thermal inkjet printing technology allows you to get reliable print heads,
stability of printers on this technology,
high printing speed.

Disadvantages of thermal printing:

It is not always possible to accurately control the size of the resulting droplets,

During operation, satellite drops may form, which degrade the quality of the resulting image,

The print head sometimes needs to be cleaned,

It is advisable to choose a special paper that will reduce ink bleeding and paper warping,

Expensive ink cartridges. Although some take the risk and order non-original ones, which are a little cheaper.

Conclusion

Thermal inkjet printing gives you the opportunity to get professional printing at a low cost. The quality of the resulting image depends on the accuracy of the nozzle manufacturing, the structure of the ejection chamber. Also, the characteristics of the dye used (viscosity, surface tension, ability to heat and evaporate) affect the image acquisition.

We hope you were interested in this article, which gave an answer to the question: what is thermal inkjet printing and in what cases it is used.